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{{#Wiki_filter:( *at:) TETRA TECH F rom: To: D ate:  
{{#Wiki_filter:FPL-030
(*at:)     TETRA TECH TECHNICAL MEMORANDUM From:        Peter F. Andersen and James L. Ross, Tetra Tech To:           Rory Rahming, Florida Power & Light Company Date:         November 13, 2014


==Subject:==
==Subject:==
TECHNICAL MEMORANDUM Peter F. Ander se n and James L. Ross, Tetra Tech Rory Rahming , F l o rid a Power & Light Com pan y November 13 , 2014 Eva lu ation ofDrawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals 1 INTROD UCT IO N 1.1 Ba c k g round Florida Powe r & Light Company (FPL) i s in the process of applying for a modification to site certification to reflect the pr oposed reduction of sa l in it y of coolin g cana l syste m (CCS) waters at the Turkey Point Power Pl a nt , l ocated ne ar F l orida City, Florida. A component of thi s pr oject i s a series of 1000-1200 foot deep we ll s that will extr ac t low sa li nity water from t h e Upper F l o ridan Aquifer a n d discharge i t into the CCS for t h e purpo se of reduc ing t he sal inity of CCS water t o l eve l s commens urat e with Biscay n e Bay. As a ste p in the site certification process, FPL must demon st r ate the feasib ili ty of withdrawing approximately 14 million gallons per day (MGD) of Upper F l oridan Aq ui fer water w ith out adver se ly impact in g th e we ll s of existing legal u se r s of the F l oridan Aquifer. This memorandum describe s th e calib r at i o n and sim ul a ti o n of a groundwater flo w model of the F l oridan Aqu if er sys tem that i s u sed to dete rmin e potentia l groundwater l eve l (drawdown) changes r es ulting f r om th e use of the F l or id an Aquifer as a so ur ce o f water fo r CCS sa linity r eduction. 1.2 Scope The scope o f thi s anal ys is i s to ca li brate a r eg i ona l groundwater flow mode l of the Upper Flo rid an Aqu i fer, as defin ed from regional hydrogeo l og i c data, in clud i ng two documented F l oridan Aquifer Pe rfo rm ance Tests (APT s). The modeling s hall meet the m i nimum requir ements of the South F l orida Water Management District (SFWMD) B asis of Rev i ew (BOR) for wate r use permitting.
Evaluation ofDrawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals 1   INTRODUCTION 1.1   Background Florida Power & Light Company (FPL) is in the process of applying for a modification to site certification to reflect the proposed reduction of salinity of cooling canal system (CCS) waters at the Turkey Point Power Plant, located near Florida City, Florida. A component of this project is a series of 1000-1200 foot deep wells that will extract low salinity water from the Upper Floridan Aquifer and discharge it into the CCS for the purpose of reducing the sal inity of CCS water to levels commensurate with Biscayne Bay. As a step in the site certification process, FPL must demonstrate the feasib ility of withdrawing approximately 14 million gallons per day (MGD) of Upper Floridan Aquifer water without adversely impacting the wells of existing legal users of the Floridan Aquifer. This memorandum describes the calibration and simulation of a groundwater flow model of the Floridan Aquifer system that is used to determine potential groundwater level (drawdown) changes resulting from the use of the Floridan Aquifer as a source of water for CCS salinity reduction.
Once calibrated, the mod el wi ll be u se d to eval u ate the a nti cipated drawdown of th e Upper Floridan Aqu i fer p ote ntiometric surface at the plant site and r egional sett in gs. T h e drawd own information will be u s ed to assess the likel y impacts to the we ll s of existing l ega l users. 1.3 R epo rt Organization Following this introducti on, the memorandum prov id es a summary of t he exi s ting r egiona l g rou ndwater model developed by the SFWMD that wa s modified andre-ca li brated. Thi s existing model is referred t o as t h e East Coast F l oridan Aquifer System Model -Phase 2 (ECF AS2). The calibration to the two APTs is th e n discussed, including changes th at were made to the ECF AS2 model and the res ultin g quality of ca libr ation. Pred i ct i ve regional s i mulations and corresponding result s fo ll ow.
1.2   Scope The scope of this analysis is to calibrate a regional groundwater flow model of the Upper Floridan Aquifer, as defined from regional hydrogeologic data, including two documented Floridan Aquifer Performance Tests (APTs). The modeling shall meet the minimum requirements of the South Florida Water Management District (SFWMD) Basis of Review (BOR) for water use permitting. Once calibrated, the model wi ll be used to evaluate the anticipated drawdown of the Upper Floridan Aquifer potentiometric surface at the plant site and regional settings. The drawdown information will be used to assess the likely impacts to the wells of existing legal users.
2 METHODOLOGY
1.3   R eport Organization Following this introduction, the memorandum provides a summary of the existing regional groundwater model developed by the SFWMD that was modified andre-calibrated. This existing model is referred to as the East Coast Floridan Aquifer System Model - Phase 2 (ECFAS2). The calibration to the two APTs is then discussed, including changes that were made to the ECF AS2 model and the resulting quality of calibration. Pred ictive regional simulations and corresponding results follow.


===2.1 Geneml===
2    METHODOLOGY 2.1   Geneml The methodology for conducting this study follows standard groundwater modeling protocols.
The methodology for conducting this s tud y follows standard groundwater modeling protocol s. As outlined in Anderson and Woessner (1992) the steps in volved with model app li cat i on include: Definition of purpose
As outlined in Anderson and Woessner (1992) the steps involved with model application include:
* Conceptua l model development
Definition of purpose
* Code se l ection Model design
* Conceptual model development
* Code selection Model design
* Calibration I verification
* Calibration I verification
* Prediction
* Prediction
* Presentation of results 2.2 Regional Model The primary purpose of the regional model analysi s i s to assess potentia l regional d r awdown resulting from pumping water from the Upper Floridan Aq uifer as a s ource of l ow-sal ini ty water for the CCS. Some of the early steps in the modeling process, most notab l y conceptual model development, model design, and, to some degree, calibration , were abbreviated in this application because the ECFAS2 model (Golder Associates, 2008) wa s available to use as the framework for the analysis.
* Presentation of results 2.2   Regional Model The primary purpose of the regional model analysis is to assess potential regional drawdown resulting from pumping water from the Upper Floridan Aquifer as a source of low-sal inity water for the CCS. Some of the early steps in the modeling process, most notably conceptual model development, model design, and, to some degree, calibration, were abbreviated in this application because the ECFAS2 model (Golder Associates, 2008) was available to use as the framework for the analysis. The abbreviated relevant steps are summarized in this section. The resulting revised model marks an FPL adaptation to the ECFAS2 model, and is herein referred to as the Adapted Floridan model.
The abbrev iat ed relevant steps are summarized in this section. The resulting revised model mark s an FPL adaptation to the ECF AS2 mode l , and i s herein referred to as the Adapted F loridan model. The conceptual model of the natural sys t em i s consistent with that de s cribed in the existing ECF AS2 model documentation (Golder Associates, 2008). Additional data to modify the hydraulic pa r ameters are ava il ab l e from s it e specific data collection and testing. Two APTs performed at the s it e are documented in JLA Geosciences (2006) and Dames and Moore (1975) and serve to supp lem ent t h e conceptual model presented in the exi s ting ECF AS2 mode l documentation (Golder Associates, 2008). The design of the orig inal model was generally un c h anged. However , the modeled domain was truncated in the north suc h that the longitudinal extent of the revised model is less than that of the original.
The conceptual model of the natural system is consistent with that described in the existing ECFAS2 model documentation (Golder Associates, 2008). Additional data to modify the hydraulic parameters are available from site specific data collection and testing. Two APTs performed at the site are documented in JLA Geosciences (2006) and Dames and Moore (1975) and serve to supplement the conceptual model presented in the existing ECFAS2 model documentation (Golder Associates, 2008).
Addit i onally, the finite difference grid spacing was modified to account for well locations used in the APTs that are simulated in the model re-calibration.
The design of the original model was generally unchanged. However, the modeled domain was truncated in the north such that the longitudinal extent of the revised model is less than that of the original. Additionally, the finite difference grid spacing was modified to account for well locations used in the APTs that are simulated in the model re-calibration. Grid modifications are described in Section 3.2. Additionally, since relative changes in flow cond itions (i.e. drawdowns) are the focus of both model calibration and predictions, only the groundwater flow component of the original model is evaluated and employed, herein. Logistically, this decision faci litated efficient model calibration and predictive simulations, as consideration of density-dependent flow and transport resulted in very long run times. The original groundwater flow and transport model was calibrated to regional water levels and saltwater concentrations. To account for site-specific conditions, the model was re-calibrated to two APTs conducted at the site.
Grid modification s are described in Section 3.2. Additiona ll y , since relative changes in flow c o nd i tions (i.e. drawdowns) are the focus of both model calibrat i on and predictions , on ly th e groundwater flow component of the origina l model is evaluated and employed, herein. Logistically , this decision faci lit ated efficient model calibration and predictive simu l at i ons, as consideration of density-dependent flow a nd transport resulted in very long run times. The orig in a l groundwater flow and transport model was calibrated to regional water level s and saltwater concentrations.
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To account for specific condit i ons, the model wa s re-calibrated to two APTs conducted at the s i te. 2 TETRA TECH 3 Regional Model Simulations


===3.1 ECFAS2===
3    Regional Model Simulations 3.1   ECFAS2 Model The SFWMD, through contractors, developed a density-dependent groundwater flow and saltwater transp01t model of the East Coast of F lorida in two phases. The first phase, ECFAS 1 (HydroGeologic, 2006), simulated the southern half of the study area (the Lower East Coast of Florida); the second phase (ECFAS2) expanded the model domain northward to include more of the East Coast of Florida (Golder Associates, 2008). Both phases of the ECFAS model are available from the SFWMD; only the former has been peer-reviewed. Nevertheless, these model s represent the best available framework from which to base a permitting-level analysis of regional Floridan Aquifer impacts resulting from pumping.
Model The SFWMD, through co ntract o r s, develop e d a den s it y-dependent gro undwat er flow and sa ltw ater tran s p01t model of th e East Coast of F l orida in two phases. T h e fir st phase, ECF AS 1 (HydroG eo logic , 2006), s imul ated the southern half of the study area (the Lower East Coast of Florida);
The ECFAS2 model encompasses the ECFAS1 region and represents a revision to the earlier work. Consequently, the ECFAS2 model was used as the framework for this analysis. The ECFAS2 model covers the much of the East Coast of Florida, from southern Indian River County to the Florida Keys. This area is discretized into uniform 2400 by 2400 ft cells.
the second phase (ECF AS2) expanded the model domain northward to includ e m o re of the East Coast of F lorid a (Golder Associates, 2008). Both phases of the ECF AS mod e l are available from the SFWMD; only the former ha s be e n peer-r ev iewed. Neve rth e le ss, these model s repre sen t the be s t ava il able framework from which to base a permitt in g-l evel analysis of regional Florida n Aqu if er impact s re s ulting from pumping. The ECFAS2 model encompa sses the ECFAS1 r eg ion and repre sents a revision to the earlier work. Consequent l y, the ECFAS2 model was used as the framework for th i s analysi s. The ECFAS2 model covers the much of the East Coast of Florida, from southern Indian River County to the Florida Keys. This area is discreti ze d into uniform 2400 by 2400 ft cells. Vertically, the model extends from land surface to the Boulder Zone , a depth of approximately 3000 ft. The vertica l section i s di sc retized int o 14 l ayers, with t he Upper Floridan Aquifer represented as 2 l ayers. B o und ary conditions are spec ified to repr esent flow into and out of the model domain, usually along the perimeter of the s tudy area. Both flow (hydraulic head s) and saltwater transport (TDS concentrations) are simu l ated a nd are dependent upon one another (density-dependent flow and transp01t). Field data from numerou s boring s were used to estab l ish the structure of the model layering, w hich represents the hydrostrati grap hic layers. In addition, field data from APTs were u sed to gu id e the initial choice of hydraulic parameters that were u s ed in the model ca libr ation. The model was calibrated to both hydraulic head s and concentrations.
Vertically, the model extends from land surface to the Boulder Zone, a depth of approximately 3000 ft. The vertical section is discretized into 14 layers, with the Upper Floridan Aquifer represented as 2 layers. Boundary conditions are specified to represent flow into and out of the model domain, usually along the perimeter of the study area. Both flow (hydraulic heads) and saltwater transport (TDS concentrations) are simulated and are dependent upon one another (density-dependent flow and transp01t) . Field data from numerous borings were used to establish the structure of the model layering, which represents the hydrostratigraphic layers. In addition, field data from APTs were used to guide the initial choice of hydraulic parameters that were used in the model calibration. The model was calibrated to both hydraulic heads and concentrations.
Even though the model was calibrated, Golder A ssoc iates (2008) found that the model's s ize resulted in exceptiona ll y long run times such that the scope of the ca li bration had to be reduced from what was orig inall y envisioned.  
Even though the model was calibrated, Golder Associates (2008) found that the model 's size resulted in exceptionally long run times such that the scope of the calibration had to be reduced from what was originally envisioned.
3.2    Adapted Floridan Model The ECFAS2 model was not usable in its avai lable state because it covers a very large area and does not provide the resolution required to accurately assess site-specific features and impacts.
Several structural modifications were made to the model and are described herein. Modifications to the calibration of the model are discussed in this section. As previously mentioned, only the groundwater flow capabilities of the ECFAS2 model were germane to the analyses of drawdown described herein, as regional changes in water quality attributable to the proposed wells, as well as the impact of such changes on drawdown, are anticipated to be negligible. Moreover, model run times were dramatically reduced by eliminating the density-dependence.
Since the Adapted Floridan model simulates groundwater flow and is adapted from the SEAWAT-based ECFAS2 model, the USGS simu lation software MODFLOW-2000 (Harbaugh, et al, 2000), a commonly applied groundwater flow model, was used to simulate the regional model. MODFLOW-2000 is capable of addressing the requirements of the SFWMD BOR inasmuch as it:
3 TETRA TECH
* simulates groundwater flow,
* is capable of addressing mu ltiple hydrostratigraphic layers and subdividing these layers such that drawdown can be computed at multiple levels within each layer, and
* is in the public domain, peer-reviewed, and widely used .
The most significant structural change to the model was the grid spacing, which was originally set at 2400 ft. For calibration purposes, the grid was refined in the immediate vicinity of the Turkey Point APTs, such that the well spacing for the APTs could be accurately represented and changes in head over small distances resolved. The revised grid spacing in the model for the calibration is shown in Figure la. The minimum grid spacing used in the Adapted Floridan model, near pumping and monitoring wells, is as little as 1.5 ft. The original model grid spacing, shown in Figut*e lb, was used in subsequent predictive runs because it was adequate for assessment of impacts at the desired scale and was practical from a run-time perspective.
The original model layering was retained because it appeared to be generally appropriate for the level of detail required. The Intermediate Confining Unit (ICU), which overlies the Upper Floridan, was represented using a single layer.
The additional pumping wells that were included as a part of the calibration of the Adapted Floridan model also represent modifications to ECF AS2. The well locations and rates are described in the calibration and model results sections below. The time stepping of the models was also modified to provide adequate resolution for the duration of the APTs and to account for intermittent pumping (Section 3.2.1.1 and 3.2.1.2).
3.2.1 Additional calibration of model Although the ECFAS2 model may represent the regional conditions fai rly well, it may not represent site-specific conditions particularly well. This hypothesis was tested by running the model using documented pumping stresses on the system and comparing the modeled response to that which was observed during the test. In general, as discussed below, the compari son was not good.      In order to obtain a reasonable representation of site-specific conditions, two additional calibrations, one to a short-term APT and another to a longer term APT, were performed. The ability to match aquifer system response to these APTs prov ides confidence that the model can predict the response to future proposed pumping. Modeled water levels were checked to ensure that the match to regional calibration targets had not been degraded as a result of the local changes. The methodology and resu lts of each of the additional calibrations are described below.
3.2.1 .1 JLA APT JLA Geosciences (2006) conducted an APT in support of the Unit 5 site certification. Floridan water supply well PW-1 was pumped for 72 hours and drawdown was measured in two other water supply wells and a shallow observation well. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibration because it was local to the area of proposed pumping and was conducted under quality-controlled conditions. However, it was recognized that the short duration of the test and extent of monitoring points would provide data that may only be representative of a relatively small area.
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Simulation of the APT was accomplished using the revised model grid. Well PW -1 was represented with a single well pumping at a rate of 4500 gpm in model layers 3 and 4, which represent the Upper Floridan Aquifer, in the cell at row 166, column 143 Timestepping ranged from a minimum of 5 to a maximum of 567 minutes, Drawdown response was noted in wells PW-3 (layers 3 and 4, row 168, column 171), PW-4 (layers 3 and 4, row 180, column 157), and OBS-1 (layer 2, row 166, column 143) at distances of 3036, 1686, and 0 feet, respectively from the pumped well. Note that OBS-1 is co-located with the pumping we ll , but is screened near the base of the Biscayne Aquifer and did not experience drawdown in response to the APT.
Comparison of modeled to observed conditions for the original model, prior to adjustment, was not good, with a residual standard deviation of greater than 100 ft. However, as shown in F igure 2, this match improved cons iderably (residual standard deviation of 0.36 ft) after adjustment of hydraulic parameters as a pmt of the calibration. In general, hydraulic conductivities were increased from their original values during calibration. Goodness-of-fit ca libration metrics are shown in Table 1 and indicate that the model provides a reasonable fit to observed data.
Table 1. Goodness of fit metrics for the JLA APT calibration Metric              Numerical Value Mean Error, ft              0.22 Mean Absolute Error, ft          0.33 Residual Standard Deviation, ft        0.36 Range of Targ_ets , ft          6.36 Residual Standard Deviation I Range *100    5.6%
Note that this calibration was conducted iteratively with the Dames and Moore APT described below and hence the calibrations strike a balance between matching the results of both APTs with the same set of parameters.
3.2.1.2 Dames and Moore APT Dames and Moore (1975) conducted an APT in support of a feasibility study for using Floridan Aquifer water to cool the original Turkey Point nuclear units. Floridan Aquifer production test well (PTW) was pumped for 90 days and drawdown was measured in eight monitoring wells at various distances from the pumped well and depths in the aquifer. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibrati on because of its long duration and use of monitoring points that were distant from the pumping well. Thus, this test was complementary to the shorter duration, more local JLA APT described above.
As in the simulation of the JLA APT, the simulation of the Dames and Moore APT was accomplished using the refined model grid. Well PTW was represented with a single well pumping at a rate of 5000 gpm in cell layers 3 and 4, row 220, and column 97. Timestepping ranged from a minimum of 73 minutes to a maximum of 11.8 days. Drawdown response was noted in wells OW-A (row 229, column 108), OW-B (row 238, column 120), OW-C (row 207,column 82), and OW-D (row 258, co lumn 181) at distances of 100 feet, 500 feet, 2000 feet, and 48,000 feet, respectively from the pumped well. Drawdown was recorded in the Upper and Middle Floridan aquifers at each of the four observation well sites, which are represented by layers 3 and 4, and 7 and 8, respectively 5
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===3.2 Adapted===
Comparison of modeled to observed conditions for the original model, prio r to adjustment, was not good (residual standard deviation in excess of I 0 ft), as was the case for the JLA APT. As shown in Figure 3, this match also improved considerably (with a residual standard deviation of 0.77 ft) after adjustment of hydraulic parameters as a part of the calibration. Goodness-of-fit calibration metrics are shown in Table 2 and indicate that the model provides a reasonable fit to observed data.
Floridan Model The ECFAS2 model was not u sa ble in its avai l able state becau se it covers a very large area and does not provide the resolution required to accurately assess site-specific features and imp acts. Several structura l modification s were made to the model and are de sc ribed herein. Modification s to the calibration of the model are discussed in this section. As previously mentioned, on l y the groundwater flow capabilities of the ECF AS2 model were germane t o the analyses of drawdown described herein , as regional changes in water quality attributable to the proposed wells, as well as the impact of s uch changes on drawdown , are anticipated to be negligible. Moreover , model run time s were dramatically reduced by eliminating the density-dependence.
Table 2. Goodness of fit mctrics fo1* the Dames and Moore APT calibration Metric                    Numerical Value Mean Error, ft                    -0.30 Mean Absolute Error, ft                  0.66 Residual Standard Deviation, ft                0.77 Range of Targets, ft                    11.8 Residual Standard Deviation I Range
Since the Adapted Floridan model s imulat es groundwate r flow and i s adapted from the SEAWAT-based ECFAS2 model, the USGS simu l at ion software MODFLOW-2000 (Harbaugh, et al , 2000), a commonly applied groundwater flow model, was u sed t o simulate the re g ional model. MODFLOW-2000 is capable of addressing the requirem ents of the SFWMD BOR inasmuch as it: 3 TETRA TECH
* 100          6.5%
* simulates groundwater flow,
Though the wells shown in Figure 3 are not an exhaustive representation of the calibration targets, they are a microcosm of the quality of the model match to this APT. The lateral and vertical proximity to the pumping well precluded a reasonable match to the observed drawdown at well OW-A (Upper); as such, this well was omitted from the calibration.
* i s capable of addressing mu l tiple hydrostratigraphic layers and subdividing these layer s s uch that drawdown can be computed at multiple l evels within each layer, and
3.2.1.3 Adjustments to the calibration The primary parameters that were changed as a result of the additional calibration were hydraulic conductivities of the Upper Floridan Aquifer (UFA), ICU, Middle Confining Unit (MCU), and the Middle Floridan Aquifer (MFA). These parameters were all raised from their orig inal values, as shown in Table 3.
* is in the public domain , peer-reviewed, and widely used. The mo s t s ignificant structural change to the model was the grid spac ing , which was o riginally set at 2400 ft. For calibration purposes , the grid was refined in the immediate vic i nity of the Turkey Point APTs , such that the well spac i ng for the APTs could be accurately represented a nd changes in head over s mall di sta nces resolved.
Note that the parameter changes were made within zones that were near the Turkey Point site and mostly in areas potentially affected by drawdown from proposed salinity reduction wells, as shown in Figure 4, 5, and 6.
The revised grid s pacing in the model for the calibration is s hown in Figure la. The minimum g rid s pacin g used in the Adapted Floridan model , n ear pump i ng and m o nitoring wells, i s as little a s 1.5 ft. The original model grid spac ing , shown in Figut*e lb , was us e d in subsequent predictive run s becau se it was adequate for asses s ment of impacts at the desired sc ale and was practical from a run-time perspective.
The changes made to the hydra ulic properties in the Adapted Floridan model are not expected to significantly impact the quality of the model match to the water level and water quality targets employed in the calibration of the ECF AS2 model. The changes made to the Adapted Floridan model were generally minor, and the preponderance of the ECFAS2 model calibration targets are located outside of the Adapted Floridan model doma in. Water levels at well ENP-100, located about 17 miles to west of Turkey Point, were simulated to be approximately 36ft, which slightl y underestimates observed water levels (approximately 37.5 ft NGVD29). The ECFAS2 model si mulates a water level of 39 feet at this location, after 350 days of simulation. Simulated water levels at W ASA-South, located to the n011h of Turkey Point, are approximately 35 ft NGVD 29; this well, however, was omitted from the ECFAS2 modeling analysis due to anomalous water levels (Golder Associates, 2008).
The o r igina l model l ayering was retained becau se it appeared to be generally appropriate f or the level of det a il required.
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The Intermediate Confining Unit (ICU), w hich overlies the Upper F l oridan, was represented u s ing a si ngle layer. The additiona l pumping wells that were included as a part of th e calibrat ion of the Adapted F l oridan m o del also repre se nt m od ification s to EC F AS2. The well loca t ions and rat es are described in the ca l ibration and model resu l ts sections below. The time ste pping of the models was also modified to provide adequate resolution for the duration of the APTs and to account for intermittent pumping (Section 3.2.1.1 and 3.2.1.2).  


====3.2.1 Additional====
Tablc3 P arameter c 1anges resu I tmg
                                  . f rom ca J'b 1 ration o f t I1c Ad apted Flone
                                                                                'I an mo d e.I ECFAS2 model                FPL Floridan Model Hydrologic    Model        Aquifer            (original)                  (recalibrated)
Unit      Layers      Parameter magnitude                      magnitude 0.0006                          0.001 Kz (fUd)
ICU          2                              0.000075                          0.001 Kh (fUd)          0.000075                          0.001 5.2                          100 Kz (fUd)                  9                            15 72.5                          225 0.33                          225 UFA        3,4                                  52                            100 Kh (ft/d)                90                            150 725                          330 3.33                          330 Ss              5.25E-07                      8.00E-07 0.004 0.003 0.000002 0.08 Kz (fUd) 0.4 0.003 MCU        5,6                                0.002 0.08 0.02 0.08 Kh (fUd)            0.00001 0.4 0.03 Kz (fUd)                5.2                           30 450                          900 MFA        7,8                                  300                          600 Kh (fUd) 180                          1200 52                          600 0.0015                          0.01 MC2      9,10,11        Kz (ft/d) 0.0002                          0.02 3.3  Predictive Simulations Once calibration of the regional Floridan model was confirmed, equilibrium flow conditions were established by running the model, holding all flow boundaries (e.g. specified heads) constant until changes in the simulated flow field in the Florida n Aquifer System were negligible. No pumping was simulated in this equi librium model. The resulting equilibrated state formed the initial conditions for ensuing predictive simulations. Equilibrated regional water 7
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calibration of model Although the ECF AS2 model may repres e nt the r eg iona l conditions fai rl y well, it may n o t represent s ite-s pecific conditions part i cu l arly well. This hypothe sis was tested by running the model u s ing documented pumping stresses on the system and comparing the modeled re s ponse to that which was observed during the test. In genera l , as d i scussed below, the compari so n was not good. In order to obtain a reasonable repre se ntation of s ite-s p ec ific condition s, two additiona l calibrations, one to a s hort-term APT and another to a l o n ge r term APT, were perform ed. The ability to match aquifer sys tem re s p o nse to the se APTs prov i des confidence that the mode l can predict th e re spo n se to future propo sed p u mpin g. Modeled water level s were checked to ensure that the match to re g iona l calibration targets had not been degraded as a re su l t of the loca l changes. Th e methodology and resu l t s of each of the additional calibrations are described below. 3.2.1.1 JLA APT JLA Geosciences (2006) conducted an APT i n support of the Unit 5 s ite certification. Floridan water supply we ll PW-1 was pumped for 72 hour s and drawdown was mea s ured in two ot her water supply wells and a shallow observat i on well. The drawdown re spo n se documented during this te st was believed to represent a good series of targets to match as a part of a calibration because i t was loca l to the area of proposed pumping and was conduct e d under quality-controlled condition s. However , it was recognized that the s hort duration of the test and extent of monitoring points would provide data that may on l y be representative of a relatively sma ll area. 4 TETRA TECH Simula ti on of the APT was accomplished using the revised model grid. Well PW -1 was represented with a single we ll pumping at a rate of 4500 gpm in model l ayers 3 and 4 , which represen t the Upper F lorid a n Aquifer , in the cell at row 166, column 143 Time s tepping ranged from a minimum of 5 to a maximum of 567 minutes, Drawdown resp o nse was noted in wells PW-3 (layer s 3 and 4, row 1 68, column 171), PW-4 (l aye rs 3 and 4, row 180, column 157), a nd OBS-1 (layer 2 , row 166, column 14 3) at distances of 3036, 1686, a nd 0 feet, re s pectively from the pumped well. Note that OBS-1 is co-located w ith the pumpin g we ll , but is screened near the ba se of the Bi scay ne Aquifer and did not exper ien ce drawdown in r espo nse t o the APT. Comparison of modeled to observed conditions for the o riginal model, prior to adjust ment , was n ot good, with a residual s tandard devi a tion of greater than 100 ft. However , as shown in F i gure 2, this match improved con s iderably (re s idual standard deviation of 0.36 ft) after adjustment of hydraulic parameter s as a pmt of the calibration.
levels, especially near Turkey Point, were generally lower than observed water levels; this is due to the exclusion of salt transport and the associated density-dependent flow. However, given that purpose of th is model is to provide estimates of relative changes in water level , the low simulated water levels were deemed irrelevant. Since the focus of the salinity reduction well evaluation is regional drawdown, the original 2400-ft grid spacing was employed for predictive simulations.
In general, hydraulic conductivitie s were increa sed from their orig in al values during calibration.
According the SFWMD BOR, predictive evaluations made with the calibrated model must be conducted using monthly stress periods that simulate average annual groundwater withdrawals subject to rainfall that alternates between average and 1-in-1 0 year draught conditions (3 months of average cond itions, followed by 12 months of drought conditions, followed by 6 months of average conditions). As such, the predictive models were conducted using 21 monthly stress periods .. Due to the specified head boundary in the topmost layer of the model, climatic stressess were not varied between average and drought conditions. Moreover, it is not anticipated that variation in rainfall would impact the Floridan aquifer over the 21-month timeframe of the simulation.
Goodness-of-fit ca l ibration metric s are s hown in Table 1 and indicate that th e model pr ovi de s a rea sona ble fit to observed data. Table 1. Goodness of fit metrics for the JLA APT calibration Metric Numerical Value Mean Error, ft 0.22 Mean Absolute Error , ft 0.33 Residual Standard Deviation, ft 0.36 Range of Targ_ets , ft 6.36 Residual Standa rd Deviation I Range *1 00 5.6% Note that this calibration was conducted iteratively with the Dame s and Moore APT described below and hence the calibrations strike a balance between matching the result s of both APTs w ith the same se t of parameters.
Additionally, the BOR stipulates that the 1-ft drawdown contour associated with the proposed pumping be simulated and the impacts to existing legal users' wells within that contour be evaluated. The process by which this was accomplished is described below.
3.2.1.2 Dames and Moore APT Dames and Moore (1975) conducted an APT in support of a fea s ibili ty st udy for us in g Floridan Aquifer water to coo l the origina l Turkey Point nuclear units. Floridan Aquifer production te s t well (P TW) was pumped for 90 days and drawdown was measured in eight monitoring wells at various distanc es from the pumped well and depth s in the aquifer. The drawdown response documented during this te s t was believed to repre s ent a good series of targets to match as a part of a ca librati on because of it s long duration and u se of monitoring points that were distant from the pumping well. Thus, this test wa s complementary to the shorter duration , more local JLA APT described above. As in the s imulation of the JLA APT, the simulation of the Dame s and Moore APT was accomp li shed using the refined model grid. Well PTW was repre se nted with a single well pumping at a rate of 5000 gpm in cell l ayers 3 and 4 , row 220, and co lumn 97. Timestepping ranged from a minimum of 73 minutes to a maximum of 11.8 days. Drawdown respon se was n oted in wells OW-A (row 229, column 108), OW-B (row 238, column 120), OW-C (row 207,column 82), and OW-D (row 258, co lumn 181) at distances of 100 feet, 500 fee t, 2000 feet, and 48,000 feet, r espectively from the pumped well. Drawdown was re cord e d in the Upper and Middle Floridan aquifers at each of the four observation well s ite s, which are represented by layers 3 and 4 , and 7 and 8, respectively 5 TETRA TECH Co mpari so n of modeled to observed conditions for the o ri g in a l mode l , pri or t o adj u s tment , was not good (re s idual s tan dard deviation in excess of I 0 ft), as was t h e case for th e JLA APT. As s h ow n in Figure 3, thi s m atc h a l so impr oved considerab l y (with a re sid ual s tandard deviati o n of 0.77 ft) afte r a dju s tment of h yd raulic parameters as a p ar t of the ca libr ation. Goodness-of
3.3.1   Proposed Salinity Reduction Well Operation There are six proposed salinity reduction wells. At any one time, five of these well s will collectively pump 14 MOD of low salinity water from the Upper Floridan aquifer. The six wells will be spaced approximately 1900 ft apart, along the northernmost canal of the Cooling Canal System and along the Interceptor Ditch (Figure 7). In the model , the 14 MGD of pumping is distributed evenly amongst the five active wells and is assumed to be a constant rate of pumping over the course of the 25-year simulation. Two alternative pumping scenarios are considered in this modeling analysis and differ in the aJJocation of pumping to wells F-2 and F-6. The base scenario simulates pumping at wells F-1 through F-5 (no pumping at F-6); the alternative scenario simulates pumping at wells F-1 and F-3 through F-6 (no pumping at F-2).
-fit calibra tion metrics are shown in Table 2 a nd ind icate that the mode l provides a rea s onab l e fit to o b se rved data. Tab l e 2. Goodness of fit mctri cs f o 1* the Dam es and Moore APT calibration Metric Numerical Value Mean E r ror, ft -0.3 0 Mean Absolute Err or, ft 0.66 Residual Standard Deviation, ft 0.77 Range of Targets, ft 11.8 Residual Sta ndard Deviation I R ange
The salinity reduction wells were simulated, starting from an equilibrium flow field. Aside from these salinity reduction wells, no pumping was simulated in this model such that the permitted users w ithin the 1-ft drawdown contour could be delineated. At the conclusion of the 21-month simu lation, the simulated drawdowns in the regional model are those attributable only to the five proposed salinity reduction wells. Figure 8a illustrates these regional drawdowns associated with the base pumping scenario. In this base simulation, the drawdowns at a distance from the site are affected by variations in hydraulic conductivity; this is evident upon inspection of the 1-ft drawdown contour, wh ich generally has an oblong shape, whose major axis is oriented north-to-south . Nearer to the site, the drawdown contours radiate outward from the wells in a more uniform manner, where the maximum drawdown is approximately 15.1 ft, near well F-3. In the alternative scenario, the maximum drawdown is approximately 14.4 ft, near well F-5.
* 1 00 6.5% Though the we ll s shown in Fig ur e 3 a r e not an ex h a u s tive representation of the cal ibration ta r gets, th ey are a microco s m of the quality o f th e m o del match to t his APT. The la teral and vert i ca l pro x imity to the pump in g we ll precluded a r easo nable mat ch to t h e obse rved drawd own at we ll OW -A (Upper); as such, t hi s well was omitted f r om the cal i bration. 3.2.1.3 Ad ju s tments to the cali br at i on T h e primary para meters t h at we r e changed as a re s ult of the additi o n a l calibrati o n were hydr a ulic con ductiviti es of the Upper Flo rid an Aqui fe r (UFA), ICU, Middle Con fining Unit (MCU), and t h e Midd l e F l o ridan Aquifer (MFA). T h ese parameters were al l raised from their or i g inal va l ues, as s h own in Table 3. Note that the parameter changes we r e made within zo ne s that we r e near the Turkey Point site a nd mostly in a r eas p otent i a ll y affected b y drawdown from pr o p osed sa linity reduction wells, as s h own in Figure 4 , 5, and 6. T h e c h a n ges made t o th e hydr a uli c prop e rtie s in the Adapted F l ori d a n mode l are n ot expected to s ignificantly impact the qualit y of th e mode l match t o th e water leve l and water qualit y targ ets emp l oyed in th e ca librati on of the ECF AS2 model. The ch an ges made to t h e Adapted Floridan model were genera ll y minor, and the preponderance of the ECF AS2 model calibration targets are l oca t e d o ut s id e of the Adapted F l oridan model d oma in. Water levels at well ENP-100, l ocated about 1 7 mil es to west of Turkey P oint, we r e s imul ated to be approximately 36ft, which s li g htl y underestimate s observed water l eve l s (approxi m ate l y 37.5 ft NGVD29). The ECFAS2 m ode l si mulates a water level of 39 feet at t h is l ocation, after 35 0 da ys of s imul ation. Simulated water levels at W ASA-South, l ocated to the n011h of Turkey Point, are approx imat e l y 35 ft NGVD 29; this we ll , however , was omitted fr om th e ECFAS2 mode l ing analysis due t o anomalous water l eve l s (Gold er Associates, 2008). 6 TETRA TECH Tablc3 P arameter c 1anges resu tmg rom ca 1 ration o t 1c a pte one an mo e. I. f J'b f I Ad d F l 'I d I ECFAS2 model FPL Floridan Model Hydrologic Model Aquifer (original) ( recalibrated) Unit La y ers Parameter magn itude magnitude 0.0006 0.001 I CU 2 Kz (fUd) 0.000075 0.001 Kh (fUd) 0.000075 0.001 5.2 100 Kz (fUd) 9 15 72.5 225 0.33 225 UFA 3,4 52 100 Kh (ft/d) 90 150 725 330 3.33 330 Ss 5.25E-07 8.00E-07 0.004 0.000002 Kz (fUd) 0.003 0.08 0.4 MCU 5 , 6 0.002 0.003 0.08 0.02 Kh (fUd) 0.00001 0.08 0.4 0.03 Kz (fUd) 5.2 30 450 900 MFA 7,8 300 600 Kh (f Ud) 180 1200 52 600 MC2 9,10,11 Kz (ft/d) 0.0015 0.01 0.0002 0.02 3.3 Predictive Simulations Once calibration of the regional Flor id an m odel was confirmed , equ ili brium flow conditi o n s were e s tabli s hed by runni ng the model, holding all flow boundari es (e.g. specified he a d s) constant until changes in the s imulated flow field in the Florid a n Aquifer S ys tem were negligible. N o pumping was s imul a ted in thi s equi li brium model. Th e r es ultin g equilibr a ted s t a te form e d t he initial condition s for en s uing predictive s imulation s. E qui li brated regional w at er 7 TETRA TECH levels , especially near Turkey Point, were generally l ower than observed water level s; this is due to the exclusion of salt transport and the associated density-dependent flow. However, given that purpo se o f th i s model i s to provide estimate s of relative changes in wate r level , the l ow simu lat ed water l eve l s were deemed irrelevant.
As previously mentioned, the SFWMD BOR dictates tbat drawdown at permitted users' wells encircled by the 1-ft drawdown contour be determined. As illustrated in Figure 8a, the following permitted users fall within the 1-ft drawdown contour:
Since the focu s of the s alinity reducti o n well evaluati on i s regional drawdown , the origina l 2400-ft g rid spacing was e mplo y ed for predictive simu l ations. According the SFWMD BOR, predictive evaluations made w ith the calibrated model mu st be conducted u s in g monthly s tre ss per i ods that simu l ate average annual groundwater withdrawals s ubject to rainfall that alternate s between averag e and 1-in-1 0 yea r draught conditions (3 months of average cond iti ons, followed by 12 month s of drought conditions , followed b y 6 mon t hs of average condit i ons). As s uch , the predictive mode l s were c o nduct ed u s in g 21 monthl y st re ss period s .. Due to the specified head boundary in the topmost la ye r of th e m ode l , clima t ic st re ssess were not varied between average and drought conditions.
8 TETRA TECH
More ove r , it i s not anticipated that variation in rainfall would impact the Floridan aquifer over the 21-month timeframe of t he simulation.
Addition a lly , the BOR stipulates that the 1-ft drawdown contour assoc i ate d with the proposed pumping be s imulated and the impacts to existing legal u sers' we ll s within that contour be evaluated.
The process b y which thi s was accompli s h ed is describ ed b e low. 3.3.1 Proposed Salinity Reduction Well Operation There a r e s ix proposed salinity reduction wells. At any one time , five of these well s will collectively pump 14 MOD of low sa linity water from the Upper Floridan aquifer. The s i x we ll s will be space d approximately 1900 ft apart , a l ong the northernm os t canal of t he Cooling Canal System and along the Intercept o r Ditch (Figure 7). In the model , the 14 MGD of pumping i s distributed evenly amongst the five active we ll s and i s assumed to be a constant rate of pumpin g over the cour se of the 25-year s imul ation. Two alternative pumping scena rio s are con s id ered in thi s modeling analysis and differ in the aJJocation of pumping to we l ls F-2 and F-6. The base scenario s imulates pumping at wells F-1 through F-5 (no pumpin g at F-6); the alternative scenario s imulate s pumping at wells F-1 and F-3 through F-6 (no pumping at F-2). The s alinity reduction w e ll s were s imulated , sta rting f rom an equilibrium flow field. A s id e from th ese s alinity reduction we ll s, no pumping was s imulated in thi s m ode l suc h that th e p e rmitted user s w ithin the 1-ft drawdown co ntour could be delineated.
At the conc lu s ion of the 2 1-m o n t h simu l ation, the simu lated drawdowns in the regional model are tho se attributable only to the five proposed sa linit y reduction we ll s. Figure 8a illu s trates these regi o nal drawdowns assoc i ated with the ba se pumping scenario.
In this base s imul a ti o n, the drawd ow n s at a distance from the site are affected by variations in hydraulic c o nductivity; this is evident up o n inspection of the 1-ft drawdown c o ntour , wh i ch generally ha s an oblong s hape , whose m ajo r axis is oriented n oto-south. Nearer to the site, the drawdown contours radiate outward from the wells in a m ore uniform manner , where the maximum drawdown is a pproximately 15.1 ft, near well F-3. In the alternativ e sce nario , the maximum drawdown i s approximate l y 14.4 ft, ne a r well F-5. As previou s ly mentioned , the SFWMD BOR dictate s tbat drawdown at permitted u sers' wells encircled b y the 1-ft drawdown contour be determined.
As illustrated in Figure 8a, the following permitted u se r s fall within the 1-f t drawdown contour: 8 TETRA TECH
* Card Sound Golf Club,
* Card Sound Golf Club,
* Ocean Reef Club,
* Ocean Reef Club,
* the F l o ridan Key s Aqueduct Authorit y (FKAA),
* the F loridan Keys Aqueduct Authority (FKAA),
* Miami-Dade Water a nd Sewage Departm e nt South Miami H eig h ts W e llfield , and
* Miami-Dade Water and Sewage Department South Miami Heights Wellfield, and
* FPL Unit 5 Wells. A second 21-month simulation was conducted wherein pumping by permitted user s and the propo sed sa linit y r e ducti o n we ll s was simulated.
* FPL Unit 5 Wells.
Predicted dra w d ow n s att r i butable so l e ly to permitted Floridan pumpin g were determined by comparing dr awdowns from thi s si mul at ion (Figure 8b) t o those attributabl e to the propo se d sa linit y reduc tio n wells alone (F igure Sa). The s e permitted we ll-ba se d dr aw down s are illu st r a ted in Figure 9 for the ba se pumping sce nari o. Pred icted drawdown s at Floridan well s of the se ex i sting le gal u se r s due to the propo se d operation of the sa linity reduction wells are pre s ented in Table 4. The s e drawdown s are ca lculat ed at the center of the m o del grid cell s in wh i ch the respectiv e w e lls are s imulated.
A second 21-month simulation was conducted wherein pumping by permitted users and the proposed salinity reduction wells was simulated. Predicted drawdowns attributable solely to permitted Floridan pumping were determined by comparing drawdowns from this simulation (Figure 8b) to those attributable to the proposed salinity reduction wells alone (Figure Sa).
In addition to drawdown s attributable to the pr o p ose d wells for the base pumping allocation scenario, cumu l ative drawd ow n s at nearby we ll s due to bot h pumpin g at permitted and proposed we lJ s are provided in Table 4. Withdrawals b y nearb y u s ers we re s im u l a t ed at their re spect i ve permitted r ates. Table 4. Predicted drawdown at nearby users for the proposed Salinity Reducti on Wells due to the base . . pumpmg scenano. Permitted Distance Base Scenar i o Base Scenario Facility Location Withdrawal from Drawdown at Cumulative (L , R , C) we ll F-2 3 , 15, and 21 (MGD) (mi l es) Months (ft) Drawdown (ft) Card Sound Golf (3-Club (WUP 44-0.58 8.8 1.85/2.20/2.21 9.83/1 1.47/1 1.54 00001) 4, 173 ,93) Ocean Reef Club (3-1.42 8.8 1.85/2.20/2.21 9.83/1 1.47/11.54 (WUP 44-00002) 4,173,93)
These permitted well-based drawdowns are illustrated in Figure 9 for the base pumping scenario. Pred icted drawdowns at Floridan wells of these existing legal users due to the proposed operation of the salinity reduction wells are presented in Table 4. These drawdowns are calculated at the center of the model grid cells in which the respective wells are simulated. In addition to drawdowns attributable to the proposed wells for the base pumping allocation scenario, cumu lative drawdowns at nearby wells due to both pumping at permitted and proposed welJs are provided in Table 4. Withdrawals by nearby users were simulated at their respective permitted rates.
FKAA (3-9.70 10.3 1.76/2.15/2.16 416.0 6/17.78/1 7.85 (WUP 13-00005) 4 , 15 5,61) South Miami Ht s (3-4 , 1 33-23.3 10.3 1.83/2.25/2
Table 4. Predicted drawdown at nearby users for the proposed Salinity Reduction Wells due to the base pumpmg scenano.
.26 46.71/48.72/48.80 (WUP 13-00017) 135,79) FPL Un i t 5 Well (3-14.3 < 1.0 11.44/11.85/11.86 34.11/35.92/35.99 (PW-1) 4, 15 6,85) A second eva lu ation was conducted in which the a l ternative pumpin g allocation (wells F-1 and F-3 through F-6) for the sa linit y reduction s wells was simulated.
Distance     Base Scenario Permitted                                        Base Scenario Location                   from       Drawdown at Facility                Withdrawal                                        Cumulative (L,R,C)                 well F-2     3,15, and 21 (MGD)                                         Drawdown (ft)
The re s ulting s im ulated drawdown s at legal user s within the 1-ft drawd ow n co ntour are provided in Table 5; cumu l at i ve drawdown s are a l so tabulated.
(miles)       Months (ft)
In s pection of the drawd ow n s in Table 5 reveals that they a re not s ignific ant l y different from those produced by the b ase pumping allocati on. The cumulative drawdown du e to permitted pumping , as illu s tra te d in Figure 9 , are not s ignifi cantly different than th ose produced by th e c o mbinati o n of pr o p ose d and p e rmi tted withdrawa l s (F igure 8b ). This s ugg es t s that the prop os ed pumpin g of F l oridan water by t he s alinit y reduction we ll s w ill n ot s i g nificantl y exacerbate dr awdow n s in the U pp e r Floridan aquifer beyond tho s e induced by existing permitted pumping. 9 TETRA TECH Tab l e 5. Predicted drawdown at neub y users f or the pr oposed Sa linity Reduction Well s due to the I . . . a ternatlve pumpmg scenano. Alternati v e A lt ernative L oca ti on Distance Scenario Scena r io Facility (L,R,C) from well Drawdown at Cumulat i ve F-2 (miles) 3 , 15, and 21 Months (ft) Drawdown (ft) Card Sou nd Golf Club (3-4, 173 , 93) 8.8 1.86/2.21/2.22 9.84/11.48
Card Sound Golf (3-Club (WUP 44-                   0.58           8.8     1.85/2.20/2.21       9.83/11.47/1 1.54 4, 173,93) 00001)
/11.5 6 (WUP 44-00001)
Ocean Reef Club         (3-1.42           8.8     1.85/2.20/2.21       9.83/1 1.47/11 .54 (WUP 44-00002)     4,173,93)
Ocean Reef Club (3-4, 1 73,93) 8.8 1.86/2.2 1/2.22 9.84/11.48/11.56 (WUP 44-00002)
FKAA             (3-9.70         10.3     1.76/2.15/2. 16   416.06/17.78/1 7.85 (WUP 13-00005)     4, 155,61)
FKAA (3-4, 155 ,6 1) 10.3 1.78/2.17/2.18 16.08/17.80/17.87 (WUP 13-00005)
South Miami Hts    (3-4, 133-23.3         10.3     1.83/2.25/2.26     46.71/48.72/48.80 (WUP 13-00017)       135,79)
South Miami Hts (3-4 , 133-10.3 1.81/2.22/2.24 4 6.6 8/48.69/48.78 (WUP 13-00017) 135,79) FPL Unit 5 Well (PW-1) (3-4 , 15 6,85) < 1.0 9.92/10.33/10.35 32.59/34.40/34.47 4 Conclusions The eva lu ation of drawdown due to pumpin g at the proposed salinity reduc tion wel l s i s ba s ed on th e EC FAS 2 model developed for the SFWMD. This model was s ub se quentl y ada pt e d to sites pecific conditions and re-calibrated to two APTs performed at Turke y Point. The re s ulting regional calibrated groundwate r flow model provides assessment of drawd ow n at nearby existing F l oridan wate r users. In a re g ional s ense, the proposed pumpin g of 1 4 MGD i s projected to result in a maximum Upper Floridan Aq ui fer drawdown rangin g between 14.4 ft (alternative sce nari o) and 15.1 ft (base sce nari o) at the Turkey Point s ite; s imulated drawdowns a t a di stance from Turkey P oint a r e no t s i g nificantly different b etwee n the two pumping s cenario s. The extent of drawdown , as defined by the 1-f t drawdown contour encompas s es four existing leg a l u sers. Overall, the im pacts to offs i te p e rmitted we ll s are minor. The ma x imum drawdown due t o the proposed sa lini ty r e duction we ll s exper i enced by the ne a re st (non-FPL) u se r s i s 2.26 ft and occ ur s at t h e South Miam i Hei g ht s we llfi e ld , loc ated approximate l y 10.3 miles away. Th i s drawdown co mpri ses approximately 4.6% of the cumulativ e drawdown s imul ated at this s it e. The drawdown contribution by the proposed sa linit y reduction we ll s i s a conservative estimate (greater than wou ld actua ll y be experienced), s inc e the drawdown in the wellbore at each n ea rby u se r due to locali ze d pumping i s undersimulated by the coarse-gr idd ed regional model. In add iti on to a demon s tration of minimal dr aw down induc ed at we ll s of permitted u se r s within the 1-ft dr awdow n contour, the BOR a l so st ipulate s that the propo se d pumping n o t impact the sa lt water interface, as defined by the 250 m g/L i soch l or. As the quality of Upper Floridan Aquifer water in this ar ea a lready excee ds s uch a concentrat i on, and no sa ltwat er interface exists, this stip ulation does not apply to the prop osed project. Moreover , the ope r atio n of the sa linity reduc t ion we ll i s not expected impact Upper F l or idan wa ter quality in a regional se n se. Local changes in water qua lit y are expected to b e minor , as demonstrated b y ot h er Upper Floridan water u se r s in t h e re g ion (SFWMD, 20 1 2). 10 TETRA TECH 5 References Anderson, M.P., and Woes s ner , W.W., 199 2, Appl i ed Groundwater Modeling-Sim ul at i on of Flow and Advective Transport:
FPL Unit 5 Well       (3-14.3         < 1.0   11.44/11 .85/11 .86   34.11/35.92/35.99 (PW-1)       4, 156,85)
San Diego, Ca, Academ ic Press, 381 p. Dame s and Moore, 1975. Floridan Aquifer Water Supply Investigation , Turkey Po int Area, Florida. Golder Assoc i ates, 2008. East Coast Floridan Aquifer System Mode l , Pha se 2 , Southeas tern Flor id a, final Model Documentation Report , October 2008, 259pp. Harbaugh , A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-wate r model --Use r guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92 , 121 p. HydroGeoLog ic, 2006. Development of a Den s it y-Dependent Saltwater Intru s i o n Model for the Lower East Coast Project A r ea, April 2006. 166 pp JLA Geosciences, 2006. Well Comp l et i on Report for F l oridan Aquifer Well s PW-1 , PW-3, and PW -4. FPL Turkey Point Expans i o n Project (Unit 5) Homestead, Florida. Langevin, C.D., D.T. Thorne, Jr, A.M. Dau s man , M.C. Sukop, and W. Guo, 2008, SEAWAT Version 4: A Computer Program for S imulation of Mu lti-Species Solute and Heat T r anspor t: USGS Techniques and Methods Book 6, Chapter A22 , 39 p. Sout h F l orida Water Management District (SFWMD), 20 1 2, Overview and Current Use of the Floridan Aquifer System in the Lower East Coast, Public Worksh op, Pompano Beach, F l orida, Apri118, 2012. Z heng , C., and P. Wang, 1 999, MT3DMS , A modular three-dimen siona l multi-species transport model for simulation of advection, dispersion and chemical reac t i ons of contaminants in g roundwater systems; documentation and u se r's guide, U.S. Army E n ginee r Research and Development Cente r Contract Report SERDP-99-1, Vick s bur g, MS, 202 p 11 TETRA TECH P.\FP L\Sali My Reduction\GISIAg1_ModciGrid mxd Legend D Calibration Model Extent D Original Model Extent --Coo ling Canals -Model Grid TITLE: L OCATION; Model Grid Spacing in the Vicinity of Turkey Point for a) Calibrat i on Model and b) Predictive Models Turkey Point, Fl o rida [ 1t:] TETRA TECH 1-C H--Ec::CKC::E=!-P'-'f,:_:A
A second evaluation was conducted in which the a lternative pumping allocation (wells F-1 and F-3 through F-6) for the salinity reductions wells was simulated. The resulting simulated drawdowns at legal users within the 1-ft drawdown contour are provided in Table 5; cumu lative drawdowns are also tabulated. Inspection of the drawdowns in Table 5 reveals that they are not significantly different from those produced by the base pumping allocation.
'------j FIGURE: DRAFTED SCS PROJ 1 17-2826019 1 DATE 031 1 0120 14 
The cumulative drawdown due to permitted pumping, as illustrated in Figure 9, are not significantly different than those produced by the combination of proposed and permitted withdrawals (Figure 8b ). This suggests that the proposed pumping of Floridan water by the salinity reduction wells will not s ignificantly exacerbate drawdowns in the Upper Floridan aquifer beyond those induced by existing permitted pumping.
---7 PW3 I 6 I 0 Simula t ed Drawdown I I -Observed D rawdow n 5 -I -, I J t 1 I II IIIII 0 II I 'II I I 7 OB Sl j 1 1 11 .I I I I 1 I ll Il l I I 1 r 1 I 0 Slmu la l cd D r awdown fl I 6 -II II I II J-ob s Orawdown , I 0 I Ill Ill I II I II I I l l 5 I I I I II I I ll 0 1 2 3 4 5 6 7 g4 I I I I I ll Il l Elapsed Tim e {d) c -o I I I II Ill 3: I 1 Ill 1 7 PW4 J I IJ JJ, I I I 1 I . 0 S imu la ted Orawdown Ill I I II I ,, II II 6 ill II -Observed Orawdown 0 I ill! I I I III I II IIIII 5 -II II II II -1 &#xa3;4 I 0 1 2 3 4 5 6 7 L I ill I I I E l ap s ed Time (d) -o II I I I I 3: IIIII I I I I 1 I II I I I Ill 0 ::r TITLE: Mod eled vs observe d drawdown fo r th e JLA AP T --1 I II I I I II I I 1111 I C alibrate d Adapted Flo ri dan Mode l 0 1 2 3 4 5 6 7 LOCAT IO N: Turkey Point , Florida E l a ps ed T ime (d) CH E C KE D. PFA F I GUR E: [ "R: I TETRA TECH l nRAFTED c JlR 2 FILE: 11 7*2826019 DATE: 031091201 4
9 TETRA TECH
---8 n ow-B Upp er 8 rt ow-B Low er I I 0 Simulated l>rawdo wn 0 Slmula1ed Orawdow n 1-7 7 -Obser v ed O raw down -O bserved Drawdow n 6 I 6 I I I I l/'"*n l I b ""II I I ;E:s ;E:s c , I c I .., II I I I .., g3 3: ,53 II"" !A I""" ..... f\, 2 2 -o o c ) ( ! c 0 h op 1 1 I . I r I I I 0 0 0 20 40 60 80 100 120 0 20 4 0 60 80 100 120 E l apsed Time (d) E l apsed T ime (d) 8 d ow-o Upper I I 8 i ow-o Lower I I I 0 Simula t ed Orawdown I I I O Si mu l lle d O r awdown r 7 I I 7 II I I I
 
* Observed Orawdown I I -Observed Orawdo wn 6 I I 6 I I I I Ill I ;E:s I ;E:s c I I I L I II .., I I I .., I 3: 3: ,53 I I I I I ,53 I I 2 2 I I I I I I . I 1 I 1 -...-nbc '*.1
Table 5. Predicted drawdown at neuby users for the proposed Salinity Reduction Wells due to the a Iternatlve
* o ,s; If. PI *"'r--"Hi .,.. 0 1 0 p O J C ? * . I .. . . I 0 0 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Elapsed Time (d) Elapsed Time (d) nne: Modeled vs observed drawdown fo r the Dames and Moore AP T -Adapted F l oridan Model lOCATION: Turkey Point, Florida CH ECKED: PFA F I GURE* ["11;] T ET R A T E CH ln RAFTEDo L R 3 FI L E: 1 17-28260 1 0 DA TE: 0)109120 1-4 P.\FPL\Salinit)'
                  . pumpmg
Redudron\GIS\Ftg4_Con<A.2.mKd Legend Origin a l Conducti vi ty --Coo li ng Cana l s CJ 3.0E-06 ft/d D 7.5E-05 ft/d D 6.0E-04 ft/d 2.5 E-03 ft/d 9.5E-03 ft/d Calib_rated Conducti vi ty CJ 3.0E-06 ft/d D 6.0E-04 ft/d -1.0 E-03 ft/d 2.5E-03 ft/d 9.5 E-03 ft/d 0 4.5 9 ,...._ __ Scattl n M I H 1 8 I m'bis tribution o f Vertical H yd rau li c Conductiv i ty i n th e Int e rm ediat e Confining Uni t a) Origin al Model, Pr i ortoAddi l ion a l Ca li b r at i on a n d b) After Add i tional Calib rat ion LOCATION: T urkey Poi nt, Florida ( '"ft:) TETRA TECH PROJ 117-2826019 DATE 03/1012014 CHECKE PFA FIGURE: OR A FTEO SCS 4 P.\fPL\Salinit)'
                        . scenano.
R edotfo n'GS\FigS_Condl 3.m xd Legend Original Conductivity D 90 ft/d 725 ft/d 55 ft/d o 224.995 wd n 52 ft/d D 1 oo ftld LJ 3.33 ftld --Coo ling Canals Calibrated Conductivity D 330 ftld D 150 ftld CJ 10 0 ftld 55 ft/d 0 5 10 20 -----Sc al e I n Mi n TITl E: Distributi o n o f Hyd r au li c Conductivity i n the Uppe r F l or i dan Aqui f e r a) Origina l Model, Prior t o Addit i onal C a libr a t i on and b) A ft e r Add i t io na l Ca li b r at io n LOC A T I O N; Turkey Point , Florida 5 [ 1'1:] TETRA TECH I::CH':"E:.::C::KE::f.:-
Alternative A lternative Distance         Scenario Location                                            Scenario Facility                           from well      Drawdown at (L,R,C)                                           Cumulative F-2 (miles)     3,15, and 21 Drawdown (ft)
P O::FA:-------J F I GURE: OR AFTE SCS P R OJ 1 17*28260 19 DATE 0 3/10120 14 P;\F PL\Salinity Redu cti on\GIS\F1g6
Months (ft)
_Coodl6.m x d Legend Original Condu c tivity --Cooling Canals CJ 2.0E-06 ft/d D 2.0E-03 ft/d D 4.0 E-0 3 ft/d 5.0E-03 ft/d D 1.5E-02 ft/d Calibrated Conductivity D 2.0E-0 3 ft/d 3.0E-0 3 ft/d D 4.0E-0 3 ft/d 1.5 E-02 ft/d 8.0 E-02 ft/d D 4.0E-01 ft/d .. _f 0 5 20 ----TITLE: Distrib uti on o f Vert i ca l H y draulic Con d u ctiv ity in t h e M id dl e Co nf i ning U n i t a) Orig i nal Mo de l , P rio r t o A dd it i ona l Calibration and b) Afte r A dd i ti o nal Cali brati o n LOCATION: Tu rkey Point , Florida ( -n:] TETRA TECH CHEC PFA FIG U R E: ORAFTE scs 6 PROJ 117-2826019 OATE 031 1 012014 P: IFPL\Salini!y Reductlon\GIS\NewWells
Card Sound Golf Club (3-4, 173,93)       8.8       1.86/2.21/2.22     9.84/11.48/11 .56 (WUP 44-00001)
_SCA.mxd Legend T ITLE:
Ocean Reef Club (3-4, 173,93)       8.8       1.86/2.21/2. 22   9.84/11.48/11.56 (WUP 44-00002)
* Proposed We ll s LOCATION:
FKAA (3-4, 155,61)       10.3       1.78/2.17/2.18   16.08/17.80/17.87 (WUP 13-00005)
* E x i st ing U nit 5 We ll s F-1 J ----* Location of Proposed Salin i ty Reduction Wells Screened in the U er Flor idan A uifer Tur k e y Point , Flor id a DRAFTED JlR ['A:) TETRA TECH C H ECKE PFA PR O J 117-2826019 D ATE 03/3 1/2014 t 1 F IG URE: 7 P.\FPL\SW'lnity Recmtion'1GI S\Re do n at_OON_21 M o_SCA.mx d Legend
South Miami Hts         (3-4, 133-10.3       1.81 /2.22/2.24   46.68/48.69/48.78 (WUP 13-00017)           135,79)
* Existing User Wells Drawdown Contours (1 ft) 0 5 10 ----
FPL Unit 5 Well (PW-1)     (3-4,156,85)       < 1.0     9.92/10.33/10.35   32.59/34.40/34.47 4   Conclusions The evaluation of drawdown due to pumping at the proposed salinity reduction wel ls is based on the ECFAS2 model developed for the SFWMD. This model was subsequently adapted to site-specific conditions and re-calibrated to two APTs performed at Turkey Point. The resulting regional calibrated groundwater flow model provides assessment of drawdown at nearby existing Floridan water users.
I n Mles TI TlE: LOCA TION: 0 5 10 -----Scat.lnMies a) Pred i cted UFA D r awdown Due to Pro pos ed Wellfie l d, and b) Cumu l ative UFA D ra wd o wn Due to P ermitted and Proposed We llfi e l ds Turkey Point , F lorida CHECK P FA [ -n::) TETRA TECH ORAFTE JLR PROJ 117-2826019 DATE 11/5/2014 FIGURE: 8 P: IFPL\Salinily Reduction'I31S\Permilled _ Q_ DDN _ 21 Mo _ SCAmxd Legend TITLE: --Drawdown Conto ur s LOCATION; --Coo ling Ca n als
In a regional sense, the proposed pumping of 14 MGD is projected to result in a maximum Upper Floridan Aquifer drawdown ranging between 14.4 ft (alternative scenario) and 15.1 ft (base scenario) at the Turkey Point site; simulated drawdowns at a distance from Turkey Point are not significantly different between the two pumping scenarios. The extent of drawdown, as defined by the 1-ft drawdown contour encompasses four existing legal users. Overall, the impacts to off-site permitted wells are minor. The maximum drawdown due to the proposed salinity reduction wells experienced by the nearest (non-FPL) users is 2.26 ft and occurs at the South Miami Heights wellfield, located approximately 10.3 miles away. Th is drawdown comprises approximately 4.6% of the cumulative drawdown simulated at this s ite. The drawdown contribution by the proposed salinity reduction wells is a conservative estimate (greater than would actually be experienced), since the drawdown in the wellbore at each nearby user due to localized pumping is undersimulated by the coarse-gridded regional model.
* Existing User Wells C lub (WUP 44-00002) 0 4 8 16 -----S i mu l ated Equi librium Drawdown in Uppe r Flo ridan Aqui f e r due to Permitted Pumping Tur key Point , Flori da DRAF T ED JLR CH E CKE PFA [ "jl;:) TETRA TECH P RO J 1 17-2826019 D AT E W S/20 1 4 FI G UR E; 9 
In addition to a demonstration of minimal drawdown induced at wells of permitted users within the 1-ft drawdown contour, the BOR also stipulates that the proposed pumping not impact the saltwater interface, as defined by the 250 mg/L isochlor. As the quality of Upper Floridan Aquifer water in this area already exceeds such a concentration, and no saltwater interface exists, this stipulation does not apply to the proposed project. Moreover, the operation of the salinity reduction well is not expected impact Upper F loridan water quality in a regional sense. Local changes in water quality are expected to be minor, as demonstrated by other Upper Floridan water users in the region (SFWMD, 20 12).
( *at:) TETRA TECH F rom: To: D ate:  
10 TETRA TECH
 
5   References Anderson, M.P., and Woessner, W.W., 1992, Appl ied Groundwater Modeling- Simulation of Flow and Advective Transport: San Diego, Ca, Academ ic Press, 381 p.
Dames and Moore, 1975. Floridan Aquifer Water Supply Investigation, Turkey Po int Area, Florida.
Golder Associates, 2008. East Coast Floridan Aquifer System Model, Phase 2, Southeastern Florida, final Model Documentation Report, October 2008, 259pp.
Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- User guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92, 121 p.
HydroGeoLogic, 2006. Development of a Density-Dependent Saltwater Intrusion Model for the Lower East Coast Project Area, April 2006. 166 pp JLA Geosciences, 2006. Well Completion Report for Floridan Aquifer Wells PW-1 , PW-3, and PW -4. FPL Turkey Point Expansion Project (Unit 5) Homestead, Florida.
Langevin, C.D., D.T. Thorne, Jr, A.M . Dausman, M.C. Sukop, and W. Guo, 2008, SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport: USGS Techniques and Methods Book 6, Chapter A22, 39 p.
South Florida Water Management District (SFWMD), 2012, Overview and Current Use of the Floridan Aquifer System in the Lower East Coast, Public Workshop, Pompano Beach, Florida, Apri118, 2012.
Zheng, C., and P. Wang, 1999, MT3DMS, A modular three-dimensional multi-species transport model for simulation of advection, dispersion and chemical reactions of contaminants in groundwater systems; documentation and user's guide, U.S. Army Engineer Research and Development Center Contract Report SERDP-99-1, Vicksburg, MS, 202 p 11 TETRA TECH
 
P.\FPL\SaliMy Reduction\GISIAg1_ModciGrid mxd Legend                                 TITLE:
Model Grid Spacing in the Vicinity of Turkey Point for a) Calibration Model and b) Predictive Models D        Calibration Model Extent        LOCATION; D        Original Model Extent                                      Turkey Point, Florida
    - - Cooling Canals
    -Model Grid
[1t:]   TETRA TECH 1-CH
                                                                                                --Ec::CKC::E=!-P'-'f,:_:A'----
DRAFTED SCS PROJ DATE 117-2826019 0311012014
                                                                                                                              - -j FIGURE:
1
 
7     PW3
                                          ~
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~4    - ,
                  ~                        I
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II I                 'II I                               I           7 OB 1
Ill Ill I I 1r1                                                I Slj 1111                              .I I       0 I       I Slmulal cd Drawdown    fl 0        I                                I 6 -
II II                         I II       J-     obs e"':'e~ Orawdown , I Ill Ill      I II I II I Il l                                         5 I                         I II II                  I I ll 0               1     2       3           4       5             6         7 g4 Elapsed Time {d)                                   c
                                                                                      ~3                I                         I II Ill                           Ill
                                                                                    -o 3:
                                                                                    ~2 -              I                         I I II                              Ill 7
PW4J I IJJJ,           I I                               I         1             I                       1 Ill                    ,, II II1 6
I    .                                       0 Simulated Orawdown Ill I                     I II I 5 -          ill II                                 -     Observed Orawdown         0 I ill!                         I IIIII I                 II IIIII
&#xa3;4 I    II II                                                   II II         -1 0       1           2       3         4           5               6           7 L               Iill                      I                             I I                                         Elaps ed Time (d)
-o 3:
~2            II  II                                                   I I 1    IIIII I             I                                         I I 0        I II I                   I         ::r                   I Ill                      TITLE:
Modeled vs observed drawdown for the JLA APT -
    -1         I II I             I I             II I                   I 1111 I                   LOCATION:
Calibrated Adapted Floridan Model 0             1     2       3           4         5           6         7                                         Turkey Point, Florida Ela psed Time (d)
I CHECKED. PFA                 FIGURE:
["R: TETRA TECH           lnRAFTEDc FILE:
JlR 117*2826019             2 DATE:   031091201 4
 
8 now-BUpper                                                                                    8 rtow-B Lower                                                            I           I 7
0   Simulated l>rawdown 0   Slmula1ed Orawdown  1-7
                                                                  -     Observed Orawdown                                                                        -       Observed Drawdown I                                                                                         I                   I I I 6                                                                                                6 l/'"*nl I                                         ~~ ~1
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                                                                                                ;E:s                                                                                   I I c
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                                                                                                ,53 II"" !A I """ .....     ~      f\,
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dow-o Upper I I                                                 0 I I Simulated Orawdown 8
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                                                                                                                                                    .   '*.1
                                                                                                                                                        . I 80
                                                                                                                                                                                ~~
100           120 Elapsed Time (d)                                                                               Elapsed Time (d) nne:
Modeled vs observed drawdown for the Dames and Moore APT -Adapted Floridan Model lOCATION:
Turkey Point, Florida CH ECKED: PFA                   FIGURE*
["11;] T ETR A T E CH             lnRAFTEDo FILE:
LR 117-2826010            3 DATE:         0)1091201-4
 
P.\FPL\Salinit)' Redudron\GIS\Ftg4_Con<A.2.mKd 0        __
4.5        9 Scattln MIH 18 I
Legend Original Conductivity - - Coo ling Cana ls Calib_rated Conductivity m'bistribution of Vertical Hydraulic Conductivity in the Interm ediate Confining Unit CJ  3.0E-06 ft/d          a) Original Model, PriortoAddilional Calibration a nd b) After Additional Calibration CJ          3.0E-06 ft/d D           7.5E-05 ft/d                   D   6.0E-04 ft/d LOCATION:
Turkey Point, Florida D          6.0E-04 ft/d                   -    1.0E-03 ft/d                                                               CHECKE PFA
('"ft:) TETRA TECH FIGURE:
2.5E-03 ft/d                         2.5E-03 ft/d                                                               ORA FTEO SCS 9.5E-03 ft/d                                                               PROJ      117-2826019      4 9.5E-03 ft/d                                                                                                     DATE      03/1012014
 
P.\fPL\Salinit)' Redotfon'GS\FigS_Condl3.mxd Legend 0          5                  10 Scale In Min 20 TITlE:
Original Conductivity                D  90 ft/d        Calibrated Conductivity          Distribution of Hydraulic Conductivity in the Upper Floridan Aqui fe r a) Original Model, Prior to Additional Calibration and b) After Additional Calibration 725 ft/d                        55 ft/d        D    330 ftld LOCATION; o        224.995 wd                  n   52 ft/d       D   150 ftld                                           Turkey Point, Florida D        1oo ftld                    LJ 3.33 ftld
                                          - - Cooling Canals CJ   100 ftld 55 ft/d
[1'1:] TETRA TECH                            I::CH':"E:.::C::KE::f.:-
ORAFTE PROJ DATE PO::FA:-------J SCS 117*2826019 03/1012014 FIGURE:
5
 
P;\FPL\Salinity Reduction\GIS\F1g6_Coodl6.mxd
_f 0
                                                                                                                        --   -- 5                          20 Legend                                   Calibrated Conductivity Original Conductivity - - Cooling Canals D    2.0E-03 ft/d       TITLE: Distribution of Vertical Hydraulic Conductivity in t he Middle Confining Unit a) Original Model, Prior to Additional Calibration and b) After Additional Calibration CJ 2.0E-06 ft/d                               3.0E-03 ft/d LOCATION:
D 2.0E-03 ft/d                           D   4.0E-03 ft/d                                       Turkey Point, Florida D 4.0E-03 ft/d D
5.0E-03 ft/d 1.5E-02 ft/d                   D 1.5E-02 ft/d 8.0E-02 ft/d 4.0E-01 ft/d
(-n:]      TETRA TECH CHEC ORAFTE PROJ OATE PFA scs 117-2826019 0311012014 FIGURE:
6
 
P:IFPL\Salini!y Reductlon\GIS\NewWells_SCA.mxd t
F-1J 1
Legend TITLE:      Location of Proposed Salinity Reduction Wells
* Proposed Wells                          Screened in the U er Floridan A uifer LOCATION:
* Existing Unit 5 Wells                              Turkey Point, Florida
['A:)  TETRA TECH CHECKE DRAFTED PROJ DATE PFA JlR 117-2826019 03/31/2014 FIGURE:
7
 
P.\FPL\SW'lnity Recmtion'1GIS\Redonat_OON_21Mo_SCA.mxd 0
5    10 Sea~ In Mles 0
                                                                                                                    ---- - 5        10 Scat.lnMies TITlE:
a) Predicted UFA Drawdown Due to Proposed Wellfield, and Legend                                                                    b) Cumulative UFA Drawdown Due to Permitted and Proposed Wellfields
* Existing User Wells                                LOCATION:
Turkey Point, Florida Drawdown Contours (1 ft)
[-n::)
CHECK  PFA            FIGURE:
ORAFTE JLR TETRA TECH                    PROJ    117-2826019      8 DATE    11/5/2014
 
P:IFPL\Salinily Reduction'I31S\Permilled_Q_ DDN_ 21 Mo_ SCAmxd Club (WUP 44-00002) 0
                                                                                                      -- 4
                                                                                                              --   8                16 Legend                                                TITLE:     Simulated Equilibrium Drawdown in Upper Floridan Aquifer
        - - Drawdown Conto urs                                                            due to Permitted Pumping LOCATION;
        - - Coo ling Canals                                                                Turkey Point, Florida CHECKE  PFA        FIGURE;
* Existing User Wells
["jl;:) TETRA TECH                      DRAF TED JLR PROJ    117-2826019    9 DAT E    W S/2014
 
FPL-030
(*at:)     TETRA TECH TECHNICAL MEMORANDUM From:        Peter F. Andersen and James L. Ross, Tetra Tech To:           Rory Rahming, Florida Power & Light Company Date:         November 13, 2014


==Subject:==
==Subject:==
TECHNICAL MEMORANDUM Peter F. Ander se n and James L. Ross, Tetra Tech Rory Rahming , F l o rid a Power & Light Com pan y November 13 , 2014 Eva lu ation ofDrawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals 1 INTROD UCT IO N 1.1 Ba c k g round Florida Powe r & Light Company (FPL) i s in the process of applying for a modification to site certification to reflect the pr oposed reduction of sa l in it y of coolin g cana l syste m (CCS) waters at the Turkey Point Power Pl a nt , l ocated ne ar F l orida City, Florida. A component of thi s pr oject i s a series of 1000-1200 foot deep we ll s that will extr ac t low sa li nity water from t h e Upper F l o ridan Aquifer a n d discharge i t into the CCS for t h e purpo se of reduc ing t he sal inity of CCS water t o l eve l s commens urat e with Biscay n e Bay. As a ste p in the site certification process, FPL must demon st r ate the feasib ili ty of withdrawing approximately 14 million gallons per day (MGD) of Upper F l oridan Aq ui fer water w ith out adver se ly impact in g th e we ll s of existing legal u se r s of the F l oridan Aquifer. This memorandum describe s th e calib r at i o n and sim ul a ti o n of a groundwater flo w model of the F l oridan Aqu if er sys tem that i s u sed to dete rmin e potentia l groundwater l eve l (drawdown) changes r es ulting f r om th e use of the F l or id an Aquifer as a so ur ce o f water fo r CCS sa linity r eduction. 1.2 Scope The scope o f thi s anal ys is i s to ca li brate a r eg i ona l groundwater flow mode l of the Upper Flo rid an Aqu i fer, as defin ed from regional hydrogeo l og i c data, in clud i ng two documented F l oridan Aquifer Pe rfo rm ance Tests (APT s). The modeling s hall meet the m i nimum requir ements of the South F l orida Water Management District (SFWMD) B asis of Rev i ew (BOR) for wate r use permitting.
Evaluation ofDrawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals 1   INTRODUCTION 1.1   Background Florida Power & Light Company (FPL) is in the process of applying for a modification to site certification to reflect the proposed reduction of salinity of cooling canal system (CCS) waters at the Turkey Point Power Plant, located near Florida City, Florida. A component of this project is a series of 1000-1200 foot deep wells that will extract low salinity water from the Upper Floridan Aquifer and discharge it into the CCS for the purpose of reducing the sal inity of CCS water to levels commensurate with Biscayne Bay. As a step in the site certification process, FPL must demonstrate the feasib ility of withdrawing approximately 14 million gallons per day (MGD) of Upper Floridan Aquifer water without adversely impacting the wells of existing legal users of the Floridan Aquifer. This memorandum describes the calibration and simulation of a groundwater flow model of the Floridan Aquifer system that is used to determine potential groundwater level (drawdown) changes resulting from the use of the Floridan Aquifer as a source of water for CCS salinity reduction.
Once calibrated, the mod el wi ll be u se d to eval u ate the a nti cipated drawdown of th e Upper Floridan Aqu i fer p ote ntiometric surface at the plant site and r egional sett in gs. T h e drawd own information will be u s ed to assess the likel y impacts to the we ll s of existing l ega l users. 1.3 R epo rt Organization Following this introducti on, the memorandum prov id es a summary of t he exi s ting r egiona l g rou ndwater model developed by the SFWMD that wa s modified andre-ca li brated. Thi s existing model is referred t o as t h e East Coast F l oridan Aquifer System Model -Phase 2 (ECF AS2). The calibration to the two APTs is th e n discussed, including changes th at were made to the ECF AS2 model and the res ultin g quality of ca libr ation. Pred i ct i ve regional s i mulations and corresponding result s fo ll ow.
1.2   Scope The scope of this analysis is to calibrate a regional groundwater flow model of the Upper Floridan Aquifer, as defined from regional hydrogeologic data, including two documented Floridan Aquifer Performance Tests (APTs). The modeling shall meet the minimum requirements of the South Florida Water Management District (SFWMD) Basis of Review (BOR) for water use permitting. Once calibrated, the model wi ll be used to evaluate the anticipated drawdown of the Upper Floridan Aquifer potentiometric surface at the plant site and regional settings. The drawdown information will be used to assess the likely impacts to the wells of existing legal users.
2 METHODOLOGY
1.3   R eport Organization Following this introduction, the memorandum provides a summary of the existing regional groundwater model developed by the SFWMD that was modified andre-calibrated. This existing model is referred to as the East Coast Floridan Aquifer System Model - Phase 2 (ECFAS2). The calibration to the two APTs is then discussed, including changes that were made to the ECF AS2 model and the resulting quality of calibration. Pred ictive regional simulations and corresponding results follow.


===2.1 Geneml===
2    METHODOLOGY 2.1   Geneml The methodology for conducting this study follows standard groundwater modeling protocols.
The methodology for conducting this s tud y follows standard groundwater modeling protocol s. As outlined in Anderson and Woessner (1992) the steps in volved with model app li cat i on include: Definition of purpose
As outlined in Anderson and Woessner (1992) the steps involved with model application include:
* Conceptua l model development
Definition of purpose
* Code se l ection Model design
* Conceptual model development
* Code selection Model design
* Calibration I verification
* Calibration I verification
* Prediction
* Prediction
* Presentation of results 2.2 Regional Model The primary purpose of the regional model analysi s i s to assess potentia l regional d r awdown resulting from pumping water from the Upper Floridan Aq uifer as a s ource of l ow-sal ini ty water for the CCS. Some of the early steps in the modeling process, most notab l y conceptual model development, model design, and, to some degree, calibration , were abbreviated in this application because the ECFAS2 model (Golder Associates, 2008) wa s available to use as the framework for the analysis.
* Presentation of results 2.2   Regional Model The primary purpose of the regional model analysis is to assess potential regional drawdown resulting from pumping water from the Upper Floridan Aquifer as a source of low-sal inity water for the CCS. Some of the early steps in the modeling process, most notably conceptual model development, model design, and, to some degree, calibration, were abbreviated in this application because the ECFAS2 model (Golder Associates, 2008) was available to use as the framework for the analysis. The abbreviated relevant steps are summarized in this section. The resulting revised model marks an FPL adaptation to the ECFAS2 model, and is herein referred to as the Adapted Floridan model.
The abbrev iat ed relevant steps are summarized in this section. The resulting revised model mark s an FPL adaptation to the ECF AS2 mode l , and i s herein referred to as the Adapted F loridan model. The conceptual model of the natural sys t em i s consistent with that de s cribed in the existing ECF AS2 model documentation (Golder Associates, 2008). Additional data to modify the hydraulic pa r ameters are ava il ab l e from s it e specific data collection and testing. Two APTs performed at the s it e are documented in JLA Geosciences (2006) and Dames and Moore (1975) and serve to supp lem ent t h e conceptual model presented in the exi s ting ECF AS2 mode l documentation (Golder Associates, 2008). The design of the orig inal model was generally un c h anged. However , the modeled domain was truncated in the north suc h that the longitudinal extent of the revised model is less than that of the original.
The conceptual model of the natural system is consistent with that described in the existing ECFAS2 model documentation (Golder Associates, 2008). Additional data to modify the hydraulic parameters are available from site specific data collection and testing. Two APTs performed at the site are documented in JLA Geosciences (2006) and Dames and Moore (1975) and serve to supplement the conceptual model presented in the existing ECFAS2 model documentation (Golder Associates, 2008).
Addit i onally, the finite difference grid spacing was modified to account for well locations used in the APTs that are simulated in the model re-calibration.
The design of the original model was generally unchanged. However, the modeled domain was truncated in the north such that the longitudinal extent of the revised model is less than that of the original. Additionally, the finite difference grid spacing was modified to account for well locations used in the APTs that are simulated in the model re-calibration. Grid modifications are described in Section 3.2. Additionally, since relative changes in flow cond itions (i.e. drawdowns) are the focus of both model calibration and predictions, only the groundwater flow component of the original model is evaluated and employed, herein. Logistically, this decision faci litated efficient model calibration and predictive simulations, as consideration of density-dependent flow and transport resulted in very long run times. The original groundwater flow and transport model was calibrated to regional water levels and saltwater concentrations. To account for site-specific conditions, the model was re-calibrated to two APTs conducted at the site.
Grid modification s are described in Section 3.2. Additiona ll y , since relative changes in flow c o nd i tions (i.e. drawdowns) are the focus of both model calibrat i on and predictions , on ly th e groundwater flow component of the origina l model is evaluated and employed, herein. Logistically , this decision faci lit ated efficient model calibration and predictive simu l at i ons, as consideration of density-dependent flow a nd transport resulted in very long run times. The orig in a l groundwater flow and transport model was calibrated to regional water level s and saltwater concentrations.
2 TETRA TECH
To account for specific condit i ons, the model wa s re-calibrated to two APTs conducted at the s i te. 2 TETRA TECH 3 Regional Model Simulations


===3.1 ECFAS2===
3    Regional Model Simulations 3.1   ECFAS2 Model The SFWMD, through contractors, developed a density-dependent groundwater flow and saltwater transp01t model of the East Coast of F lorida in two phases. The first phase, ECFAS 1 (HydroGeologic, 2006), simulated the southern half of the study area (the Lower East Coast of Florida); the second phase (ECFAS2) expanded the model domain northward to include more of the East Coast of Florida (Golder Associates, 2008). Both phases of the ECFAS model are available from the SFWMD; only the former has been peer-reviewed. Nevertheless, these model s represent the best available framework from which to base a permitting-level analysis of regional Floridan Aquifer impacts resulting from pumping.
Model The SFWMD, through co ntract o r s, develop e d a den s it y-dependent gro undwat er flow and sa ltw ater tran s p01t model of th e East Coast of F l orida in two phases. T h e fir st phase, ECF AS 1 (HydroG eo logic , 2006), s imul ated the southern half of the study area (the Lower East Coast of Florida);
The ECFAS2 model encompasses the ECFAS1 region and represents a revision to the earlier work. Consequently, the ECFAS2 model was used as the framework for this analysis. The ECFAS2 model covers the much of the East Coast of Florida, from southern Indian River County to the Florida Keys. This area is discretized into uniform 2400 by 2400 ft cells.
the second phase (ECF AS2) expanded the model domain northward to includ e m o re of the East Coast of F lorid a (Golder Associates, 2008). Both phases of the ECF AS mod e l are available from the SFWMD; only the former ha s be e n peer-r ev iewed. Neve rth e le ss, these model s repre sen t the be s t ava il able framework from which to base a permitt in g-l evel analysis of regional Florida n Aqu if er impact s re s ulting from pumping. The ECFAS2 model encompa sses the ECFAS1 r eg ion and repre sents a revision to the earlier work. Consequent l y, the ECFAS2 model was used as the framework for th i s analysi s. The ECFAS2 model covers the much of the East Coast of Florida, from southern Indian River County to the Florida Keys. This area is discreti ze d into uniform 2400 by 2400 ft cells. Vertically, the model extends from land surface to the Boulder Zone , a depth of approximately 3000 ft. The vertica l section i s di sc retized int o 14 l ayers, with t he Upper Floridan Aquifer represented as 2 l ayers. B o und ary conditions are spec ified to repr esent flow into and out of the model domain, usually along the perimeter of the s tudy area. Both flow (hydraulic head s) and saltwater transport (TDS concentrations) are simu l ated a nd are dependent upon one another (density-dependent flow and transp01t). Field data from numerou s boring s were used to estab l ish the structure of the model layering, w hich represents the hydrostrati grap hic layers. In addition, field data from APTs were u sed to gu id e the initial choice of hydraulic parameters that were u s ed in the model ca libr ation. The model was calibrated to both hydraulic head s and concentrations.
Vertically, the model extends from land surface to the Boulder Zone, a depth of approximately 3000 ft. The vertical section is discretized into 14 layers, with the Upper Floridan Aquifer represented as 2 layers. Boundary conditions are specified to represent flow into and out of the model domain, usually along the perimeter of the study area. Both flow (hydraulic heads) and saltwater transport (TDS concentrations) are simulated and are dependent upon one another (density-dependent flow and transp01t) . Field data from numerous borings were used to establish the structure of the model layering, which represents the hydrostratigraphic layers. In addition, field data from APTs were used to guide the initial choice of hydraulic parameters that were used in the model calibration. The model was calibrated to both hydraulic heads and concentrations.
Even though the model was calibrated, Golder A ssoc iates (2008) found that the model's s ize resulted in exceptiona ll y long run times such that the scope of the ca li bration had to be reduced from what was orig inall y envisioned.  
Even though the model was calibrated, Golder Associates (2008) found that the model 's size resulted in exceptionally long run times such that the scope of the calibration had to be reduced from what was originally envisioned.
3.2    Adapted Floridan Model The ECFAS2 model was not usable in its avai lable state because it covers a very large area and does not provide the resolution required to accurately assess site-specific features and impacts.
Several structural modifications were made to the model and are described herein. Modifications to the calibration of the model are discussed in this section. As previously mentioned, only the groundwater flow capabilities of the ECFAS2 model were germane to the analyses of drawdown described herein, as regional changes in water quality attributable to the proposed wells, as well as the impact of such changes on drawdown, are anticipated to be negligible. Moreover, model run times were dramatically reduced by eliminating the density-dependence.
Since the Adapted Floridan model simulates groundwater flow and is adapted from the SEAWAT-based ECFAS2 model, the USGS simu lation software MODFLOW-2000 (Harbaugh, et al, 2000), a commonly applied groundwater flow model, was used to simulate the regional model. MODFLOW-2000 is capable of addressing the requirements of the SFWMD BOR inasmuch as it:
3 TETRA TECH
* simulates groundwater flow,
* is capable of addressing mu ltiple hydrostratigraphic layers and subdividing these layers such that drawdown can be computed at multiple levels within each layer, and
* is in the public domain, peer-reviewed, and widely used .
The most significant structural change to the model was the grid spacing, which was originally set at 2400 ft. For calibration purposes, the grid was refined in the immediate vicinity of the Turkey Point APTs, such that the well spacing for the APTs could be accurately represented and changes in head over small distances resolved. The revised grid spacing in the model for the calibration is shown in Figure la. The minimum grid spacing used in the Adapted Floridan model, near pumping and monitoring wells, is as little as 1.5 ft. The original model grid spacing, shown in Figut*e lb, was used in subsequent predictive runs because it was adequate for assessment of impacts at the desired scale and was practical from a run-time perspective.
The original model layering was retained because it appeared to be generally appropriate for the level of detail required. The Intermediate Confining Unit (ICU), which overlies the Upper Floridan, was represented using a single layer.
The additional pumping wells that were included as a part of the calibration of the Adapted Floridan model also represent modifications to ECF AS2. The well locations and rates are described in the calibration and model results sections below. The time stepping of the models was also modified to provide adequate resolution for the duration of the APTs and to account for intermittent pumping (Section 3.2.1.1 and 3.2.1.2).
3.2.1 Additional calibration of model Although the ECFAS2 model may represent the regional conditions fai rly well, it may not represent site-specific conditions particularly well. This hypothesis was tested by running the model using documented pumping stresses on the system and comparing the modeled response to that which was observed during the test. In general, as discussed below, the compari son was not good.      In order to obtain a reasonable representation of site-specific conditions, two additional calibrations, one to a short-term APT and another to a longer term APT, were performed. The ability to match aquifer system response to these APTs prov ides confidence that the model can predict the response to future proposed pumping. Modeled water levels were checked to ensure that the match to regional calibration targets had not been degraded as a result of the local changes. The methodology and resu lts of each of the additional calibrations are described below.
3.2.1 .1 JLA APT JLA Geosciences (2006) conducted an APT in support of the Unit 5 site certification. Floridan water supply well PW-1 was pumped for 72 hours and drawdown was measured in two other water supply wells and a shallow observation well. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibration because it was local to the area of proposed pumping and was conducted under quality-controlled conditions. However, it was recognized that the short duration of the test and extent of monitoring points would provide data that may only be representative of a relatively small area.
4 TETRA TECH
 
Simulation of the APT was accomplished using the revised model grid. Well PW -1 was represented with a single well pumping at a rate of 4500 gpm in model layers 3 and 4, which represent the Upper Floridan Aquifer, in the cell at row 166, column 143 Timestepping ranged from a minimum of 5 to a maximum of 567 minutes, Drawdown response was noted in wells PW-3 (layers 3 and 4, row 168, column 171), PW-4 (layers 3 and 4, row 180, column 157), and OBS-1 (layer 2, row 166, column 143) at distances of 3036, 1686, and 0 feet, respectively from the pumped well. Note that OBS-1 is co-located with the pumping we ll , but is screened near the base of the Biscayne Aquifer and did not experience drawdown in response to the APT.
Comparison of modeled to observed conditions for the original model, prior to adjustment, was not good, with a residual standard deviation of greater than 100 ft. However, as shown in F igure 2, this match improved cons iderably (residual standard deviation of 0.36 ft) after adjustment of hydraulic parameters as a pmt of the calibration. In general, hydraulic conductivities were increased from their original values during calibration. Goodness-of-fit ca libration metrics are shown in Table 1 and indicate that the model provides a reasonable fit to observed data.
Table 1. Goodness of fit metrics for the JLA APT calibration Metric              Numerical Value Mean Error, ft              0.22 Mean Absolute Error, ft          0.33 Residual Standard Deviation, ft        0.36 Range of Targ_ets , ft          6.36 Residual Standard Deviation I Range *100    5.6%
Note that this calibration was conducted iteratively with the Dames and Moore APT described below and hence the calibrations strike a balance between matching the results of both APTs with the same set of parameters.
3.2.1.2 Dames and Moore APT Dames and Moore (1975) conducted an APT in support of a feasibility study for using Floridan Aquifer water to cool the original Turkey Point nuclear units. Floridan Aquifer production test well (PTW) was pumped for 90 days and drawdown was measured in eight monitoring wells at various distances from the pumped well and depths in the aquifer. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibrati on because of its long duration and use of monitoring points that were distant from the pumping well. Thus, this test was complementary to the shorter duration, more local JLA APT described above.
As in the simulation of the JLA APT, the simulation of the Dames and Moore APT was accomplished using the refined model grid. Well PTW was represented with a single well pumping at a rate of 5000 gpm in cell layers 3 and 4, row 220, and column 97. Timestepping ranged from a minimum of 73 minutes to a maximum of 11.8 days. Drawdown response was noted in wells OW-A (row 229, column 108), OW-B (row 238, column 120), OW-C (row 207,column 82), and OW-D (row 258, co lumn 181) at distances of 100 feet, 500 feet, 2000 feet, and 48,000 feet, respectively from the pumped well. Drawdown was recorded in the Upper and Middle Floridan aquifers at each of the four observation well sites, which are represented by layers 3 and 4, and 7 and 8, respectively 5
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===3.2 Adapted===
Comparison of modeled to observed conditions for the original model, prio r to adjustment, was not good (residual standard deviation in excess of I 0 ft), as was the case for the JLA APT. As shown in Figure 3, this match also improved considerably (with a residual standard deviation of 0.77 ft) after adjustment of hydraulic parameters as a part of the calibration. Goodness-of-fit calibration metrics are shown in Table 2 and indicate that the model provides a reasonable fit to observed data.
Floridan Model The ECFAS2 model was not u sa ble in its avai l able state becau se it covers a very large area and does not provide the resolution required to accurately assess site-specific features and imp acts. Several structura l modification s were made to the model and are de sc ribed herein. Modification s to the calibration of the model are discussed in this section. As previously mentioned, on l y the groundwater flow capabilities of the ECF AS2 model were germane t o the analyses of drawdown described herein , as regional changes in water quality attributable to the proposed wells, as well as the impact of s uch changes on drawdown , are anticipated to be negligible. Moreover , model run time s were dramatically reduced by eliminating the density-dependence.
Table 2. Goodness of fit mctrics fo1* the Dames and Moore APT calibration Metric                    Numerical Value Mean Error, ft                    -0.30 Mean Absolute Error, ft                  0.66 Residual Standard Deviation, ft                0.77 Range of Targets, ft                    11.8 Residual Standard Deviation I Range
Since the Adapted Floridan model s imulat es groundwate r flow and i s adapted from the SEAWAT-based ECFAS2 model, the USGS simu l at ion software MODFLOW-2000 (Harbaugh, et al , 2000), a commonly applied groundwater flow model, was u sed t o simulate the re g ional model. MODFLOW-2000 is capable of addressing the requirem ents of the SFWMD BOR inasmuch as it: 3 TETRA TECH
* 100          6.5%
* simulates groundwater flow,
Though the wells shown in Figure 3 are not an exhaustive representation of the calibration targets, they are a microcosm of the quality of the model match to this APT. The lateral and vertical proximity to the pumping well precluded a reasonable match to the observed drawdown at well OW-A (Upper); as such, this well was omitted from the calibration.
* i s capable of addressing mu l tiple hydrostratigraphic layers and subdividing these layer s s uch that drawdown can be computed at multiple l evels within each layer, and
3.2.1.3 Adjustments to the calibration The primary parameters that were changed as a result of the additional calibration were hydraulic conductivities of the Upper Floridan Aquifer (UFA), ICU, Middle Confining Unit (MCU), and the Middle Floridan Aquifer (MFA). These parameters were all raised from their orig inal values, as shown in Table 3.
* is in the public domain , peer-reviewed, and widely used. The mo s t s ignificant structural change to the model was the grid spac ing , which was o riginally set at 2400 ft. For calibration purposes , the grid was refined in the immediate vic i nity of the Turkey Point APTs , such that the well spac i ng for the APTs could be accurately represented a nd changes in head over s mall di sta nces resolved.
Note that the parameter changes were made within zones that were near the Turkey Point site and mostly in areas potentially affected by drawdown from proposed salinity reduction wells, as shown in Figure 4, 5, and 6.
The revised grid s pacing in the model for the calibration is s hown in Figure la. The minimum g rid s pacin g used in the Adapted Floridan model , n ear pump i ng and m o nitoring wells, i s as little a s 1.5 ft. The original model grid spac ing , shown in Figut*e lb , was us e d in subsequent predictive run s becau se it was adequate for asses s ment of impacts at the desired sc ale and was practical from a run-time perspective.
The changes made to the hydra ulic properties in the Adapted Floridan model are not expected to significantly impact the quality of the model match to the water level and water quality targets employed in the calibration of the ECF AS2 model. The changes made to the Adapted Floridan model were generally minor, and the preponderance of the ECFAS2 model calibration targets are located outside of the Adapted Floridan model doma in. Water levels at well ENP-100, located about 17 miles to west of Turkey Point, were simulated to be approximately 36ft, which slightl y underestimates observed water levels (approximately 37.5 ft NGVD29). The ECFAS2 model si mulates a water level of 39 feet at this location, after 350 days of simulation. Simulated water levels at W ASA-South, located to the n011h of Turkey Point, are approximately 35 ft NGVD 29; this well, however, was omitted from the ECFAS2 modeling analysis due to anomalous water levels (Golder Associates, 2008).
The o r igina l model l ayering was retained becau se it appeared to be generally appropriate f or the level of det a il required.
6 TETRA TECH
The Intermediate Confining Unit (ICU), w hich overlies the Upper F l oridan, was represented u s ing a si ngle layer. The additiona l pumping wells that were included as a part of th e calibrat ion of the Adapted F l oridan m o del also repre se nt m od ification s to EC F AS2. The well loca t ions and rat es are described in the ca l ibration and model resu l ts sections below. The time ste pping of the models was also modified to provide adequate resolution for the duration of the APTs and to account for intermittent pumping (Section 3.2.1.1 and 3.2.1.2).  


====3.2.1 Additional====
Tablc3 P arameter c 1anges resu I tmg
                                  . f rom ca J'b 1 ration o f t I1c Ad apted Flone
                                                                                'I an mo d e.I ECFAS2 model                FPL Floridan Model Hydrologic    Model        Aquifer            (original)                  (recalibrated)
Unit      Layers      Parameter magnitude                      magnitude 0.0006                          0.001 Kz (fUd)
ICU          2                              0.000075                          0.001 Kh (fUd)          0.000075                          0.001 5.2                          100 Kz (fUd)                  9                            15 72.5                          225 0.33                          225 UFA        3,4                                  52                            100 Kh (ft/d)                90                            150 725                          330 3.33                          330 Ss              5.25E-07                      8.00E-07 0.004 0.003 0.000002 0.08 Kz (fUd) 0.4 0.003 MCU        5,6                                0.002 0.08 0.02 0.08 Kh (fUd)            0.00001 0.4 0.03 Kz (fUd)                5.2                           30 450                          900 MFA        7,8                                  300                          600 Kh (fUd) 180                          1200 52                          600 0.0015                          0.01 MC2      9,10,11        Kz (ft/d) 0.0002                          0.02 3.3  Predictive Simulations Once calibration of the regional Floridan model was confirmed, equilibrium flow conditions were established by running the model, holding all flow boundaries (e.g. specified heads) constant until changes in the simulated flow field in the Florida n Aquifer System were negligible. No pumping was simulated in this equi librium model. The resulting equilibrated state formed the initial conditions for ensuing predictive simulations. Equilibrated regional water 7
TETRA TECH


calibration of model Although the ECF AS2 model may repres e nt the r eg iona l conditions fai rl y well, it may n o t represent s ite-s pecific conditions part i cu l arly well. This hypothe sis was tested by running the model u s ing documented pumping stresses on the system and comparing the modeled re s ponse to that which was observed during the test. In genera l , as d i scussed below, the compari so n was not good. In order to obtain a reasonable repre se ntation of s ite-s p ec ific condition s, two additiona l calibrations, one to a s hort-term APT and another to a l o n ge r term APT, were perform ed. The ability to match aquifer sys tem re s p o nse to the se APTs prov i des confidence that the mode l can predict th e re spo n se to future propo sed p u mpin g. Modeled water level s were checked to ensure that the match to re g iona l calibration targets had not been degraded as a re su l t of the loca l changes. Th e methodology and resu l t s of each of the additional calibrations are described below. 3.2.1.1 JLA APT JLA Geosciences (2006) conducted an APT i n support of the Unit 5 s ite certification. Floridan water supply we ll PW-1 was pumped for 72 hour s and drawdown was mea s ured in two ot her water supply wells and a shallow observat i on well. The drawdown re spo n se documented during this te st was believed to represent a good series of targets to match as a part of a calibration because i t was loca l to the area of proposed pumping and was conduct e d under quality-controlled condition s. However , it was recognized that the s hort duration of the test and extent of monitoring points would provide data that may on l y be representative of a relatively sma ll area. 4 TETRA TECH Simula ti on of the APT was accomplished using the revised model grid. Well PW -1 was represented with a single we ll pumping at a rate of 4500 gpm in model l ayers 3 and 4 , which represen t the Upper F lorid a n Aquifer , in the cell at row 166, column 143 Time s tepping ranged from a minimum of 5 to a maximum of 567 minutes, Drawdown resp o nse was noted in wells PW-3 (layer s 3 and 4, row 1 68, column 171), PW-4 (l aye rs 3 and 4, row 180, column 157), a nd OBS-1 (layer 2 , row 166, column 14 3) at distances of 3036, 1686, a nd 0 feet, re s pectively from the pumped well. Note that OBS-1 is co-located w ith the pumpin g we ll , but is screened near the ba se of the Bi scay ne Aquifer and did not exper ien ce drawdown in r espo nse t o the APT. Comparison of modeled to observed conditions for the o riginal model, prior to adjust ment , was n ot good, with a residual s tandard devi a tion of greater than 100 ft. However , as shown in F i gure 2, this match improved con s iderably (re s idual standard deviation of 0.36 ft) after adjustment of hydraulic parameter s as a pmt of the calibration.
levels, especially near Turkey Point, were generally lower than observed water levels; this is due to the exclusion of salt transport and the associated density-dependent flow. However, given that purpose of th is model is to provide estimates of relative changes in water level , the low simulated water levels were deemed irrelevant. Since the focus of the salinity reduction well evaluation is regional drawdown, the original 2400-ft grid spacing was employed for predictive simulations.
In general, hydraulic conductivitie s were increa sed from their orig in al values during calibration.
According the SFWMD BOR, predictive evaluations made with the calibrated model must be conducted using monthly stress periods that simulate average annual groundwater withdrawals subject to rainfall that alternates between average and 1-in-1 0 year draught conditions (3 months of average cond itions, followed by 12 months of drought conditions, followed by 6 months of average conditions). As such, the predictive models were conducted using 21 monthly stress periods .. Due to the specified head boundary in the topmost layer of the model, climatic stressess were not varied between average and drought conditions. Moreover, it is not anticipated that variation in rainfall would impact the Floridan aquifer over the 21-month timeframe of the simulation.
Goodness-of-fit ca l ibration metric s are s hown in Table 1 and indicate that th e model pr ovi de s a rea sona ble fit to observed data. Table 1. Goodness of fit metrics for the JLA APT calibration Metric Numerical Value Mean Error, ft 0.22 Mean Absolute Error , ft 0.33 Residual Standard Deviation, ft 0.36 Range of Targ_ets , ft 6.36 Residual Standa rd Deviation I Range *1 00 5.6% Note that this calibration was conducted iteratively with the Dame s and Moore APT described below and hence the calibrations strike a balance between matching the result s of both APTs w ith the same se t of parameters.
Additionally, the BOR stipulates that the 1-ft drawdown contour associated with the proposed pumping be simulated and the impacts to existing legal users' wells within that contour be evaluated. The process by which this was accomplished is described below.
3.2.1.2 Dames and Moore APT Dames and Moore (1975) conducted an APT in support of a fea s ibili ty st udy for us in g Floridan Aquifer water to coo l the origina l Turkey Point nuclear units. Floridan Aquifer production te s t well (P TW) was pumped for 90 days and drawdown was measured in eight monitoring wells at various distanc es from the pumped well and depth s in the aquifer. The drawdown response documented during this te s t was believed to repre s ent a good series of targets to match as a part of a ca librati on because of it s long duration and u se of monitoring points that were distant from the pumping well. Thus, this test wa s complementary to the shorter duration , more local JLA APT described above. As in the s imulation of the JLA APT, the simulation of the Dame s and Moore APT was accomp li shed using the refined model grid. Well PTW was repre se nted with a single well pumping at a rate of 5000 gpm in cell l ayers 3 and 4 , row 220, and co lumn 97. Timestepping ranged from a minimum of 73 minutes to a maximum of 11.8 days. Drawdown respon se was n oted in wells OW-A (row 229, column 108), OW-B (row 238, column 120), OW-C (row 207,column 82), and OW-D (row 258, co lumn 181) at distances of 100 feet, 500 fee t, 2000 feet, and 48,000 feet, r espectively from the pumped well. Drawdown was re cord e d in the Upper and Middle Floridan aquifers at each of the four observation well s ite s, which are represented by layers 3 and 4 , and 7 and 8, respectively 5 TETRA TECH Co mpari so n of modeled to observed conditions for the o ri g in a l mode l , pri or t o adj u s tment , was not good (re s idual s tan dard deviation in excess of I 0 ft), as was t h e case for th e JLA APT. As s h ow n in Figure 3, thi s m atc h a l so impr oved considerab l y (with a re sid ual s tandard deviati o n of 0.77 ft) afte r a dju s tment of h yd raulic parameters as a p ar t of the ca libr ation. Goodness-of
3.3.1   Proposed Salinity Reduction Well Operation There are six proposed salinity reduction wells. At any one time, five of these well s will collectively pump 14 MOD of low salinity water from the Upper Floridan aquifer. The six wells will be spaced approximately 1900 ft apart, along the northernmost canal of the Cooling Canal System and along the Interceptor Ditch (Figure 7). In the model , the 14 MGD of pumping is distributed evenly amongst the five active wells and is assumed to be a constant rate of pumping over the course of the 25-year simulation. Two alternative pumping scenarios are considered in this modeling analysis and differ in the aJJocation of pumping to wells F-2 and F-6. The base scenario simulates pumping at wells F-1 through F-5 (no pumping at F-6); the alternative scenario simulates pumping at wells F-1 and F-3 through F-6 (no pumping at F-2).
-fit calibra tion metrics are shown in Table 2 a nd ind icate that the mode l provides a rea s onab l e fit to o b se rved data. Tab l e 2. Goodness of fit mctri cs f o 1* the Dam es and Moore APT calibration Metric Numerical Value Mean E r ror, ft -0.3 0 Mean Absolute Err or, ft 0.66 Residual Standard Deviation, ft 0.77 Range of Targets, ft 11.8 Residual Sta ndard Deviation I R ange
The salinity reduction wells were simulated, starting from an equilibrium flow field. Aside from these salinity reduction wells, no pumping was simulated in this model such that the permitted users w ithin the 1-ft drawdown contour could be delineated. At the conclusion of the 21-month simu lation, the simulated drawdowns in the regional model are those attributable only to the five proposed salinity reduction wells. Figure 8a illustrates these regional drawdowns associated with the base pumping scenario. In this base simulation, the drawdowns at a distance from the site are affected by variations in hydraulic conductivity; this is evident upon inspection of the 1-ft drawdown contour, wh ich generally has an oblong shape, whose major axis is oriented north-to-south . Nearer to the site, the drawdown contours radiate outward from the wells in a more uniform manner, where the maximum drawdown is approximately 15.1 ft, near well F-3. In the alternative scenario, the maximum drawdown is approximately 14.4 ft, near well F-5.
* 1 00 6.5% Though the we ll s shown in Fig ur e 3 a r e not an ex h a u s tive representation of the cal ibration ta r gets, th ey are a microco s m of the quality o f th e m o del match to t his APT. The la teral and vert i ca l pro x imity to the pump in g we ll precluded a r easo nable mat ch to t h e obse rved drawd own at we ll OW -A (Upper); as such, t hi s well was omitted f r om the cal i bration. 3.2.1.3 Ad ju s tments to the cali br at i on T h e primary para meters t h at we r e changed as a re s ult of the additi o n a l calibrati o n were hydr a ulic con ductiviti es of the Upper Flo rid an Aqui fe r (UFA), ICU, Middle Con fining Unit (MCU), and t h e Midd l e F l o ridan Aquifer (MFA). T h ese parameters were al l raised from their or i g inal va l ues, as s h own in Table 3. Note that the parameter changes we r e made within zo ne s that we r e near the Turkey Point site a nd mostly in a r eas p otent i a ll y affected b y drawdown from pr o p osed sa linity reduction wells, as s h own in Figure 4 , 5, and 6. T h e c h a n ges made t o th e hydr a uli c prop e rtie s in the Adapted F l ori d a n mode l are n ot expected to s ignificantly impact the qualit y of th e mode l match t o th e water leve l and water qualit y targ ets emp l oyed in th e ca librati on of the ECF AS2 model. The ch an ges made to t h e Adapted Floridan model were genera ll y minor, and the preponderance of the ECF AS2 model calibration targets are l oca t e d o ut s id e of the Adapted F l oridan model d oma in. Water levels at well ENP-100, l ocated about 1 7 mil es to west of Turkey P oint, we r e s imul ated to be approximately 36ft, which s li g htl y underestimate s observed water l eve l s (approxi m ate l y 37.5 ft NGVD29). The ECFAS2 m ode l si mulates a water level of 39 feet at t h is l ocation, after 35 0 da ys of s imul ation. Simulated water levels at W ASA-South, l ocated to the n011h of Turkey Point, are approx imat e l y 35 ft NGVD 29; this we ll , however , was omitted fr om th e ECFAS2 mode l ing analysis due t o anomalous water l eve l s (Gold er Associates, 2008). 6 TETRA TECH Tablc3 P arameter c 1anges resu tmg rom ca 1 ration o t 1c a pte one an mo e. I. f J'b f I Ad d F l 'I d I ECFAS2 model FPL Floridan Model Hydrologic Model Aquifer (original) ( recalibrated) Unit La y ers Parameter magn itude magnitude 0.0006 0.001 I CU 2 Kz (fUd) 0.000075 0.001 Kh (fUd) 0.000075 0.001 5.2 100 Kz (fUd) 9 15 72.5 225 0.33 225 UFA 3,4 52 100 Kh (ft/d) 90 150 725 330 3.33 330 Ss 5.25E-07 8.00E-07 0.004 0.000002 Kz (fUd) 0.003 0.08 0.4 MCU 5 , 6 0.002 0.003 0.08 0.02 Kh (fUd) 0.00001 0.08 0.4 0.03 Kz (fUd) 5.2 30 450 900 MFA 7,8 300 600 Kh (f Ud) 180 1200 52 600 MC2 9,10,11 Kz (ft/d) 0.0015 0.01 0.0002 0.02 3.3 Predictive Simulations Once calibration of the regional Flor id an m odel was confirmed , equ ili brium flow conditi o n s were e s tabli s hed by runni ng the model, holding all flow boundari es (e.g. specified he a d s) constant until changes in the s imulated flow field in the Florid a n Aquifer S ys tem were negligible. N o pumping was s imul a ted in thi s equi li brium model. Th e r es ultin g equilibr a ted s t a te form e d t he initial condition s for en s uing predictive s imulation s. E qui li brated regional w at er 7 TETRA TECH levels , especially near Turkey Point, were generally l ower than observed water level s; this is due to the exclusion of salt transport and the associated density-dependent flow. However, given that purpo se o f th i s model i s to provide estimate s of relative changes in wate r level , the l ow simu lat ed water l eve l s were deemed irrelevant.
As previously mentioned, the SFWMD BOR dictates tbat drawdown at permitted users' wells encircled by the 1-ft drawdown contour be determined. As illustrated in Figure 8a, the following permitted users fall within the 1-ft drawdown contour:
Since the focu s of the s alinity reducti o n well evaluati on i s regional drawdown , the origina l 2400-ft g rid spacing was e mplo y ed for predictive simu l ations. According the SFWMD BOR, predictive evaluations made w ith the calibrated model mu st be conducted u s in g monthly s tre ss per i ods that simu l ate average annual groundwater withdrawals s ubject to rainfall that alternate s between averag e and 1-in-1 0 yea r draught conditions (3 months of average cond iti ons, followed by 12 month s of drought conditions , followed b y 6 mon t hs of average condit i ons). As s uch , the predictive mode l s were c o nduct ed u s in g 21 monthl y st re ss period s .. Due to the specified head boundary in the topmost la ye r of th e m ode l , clima t ic st re ssess were not varied between average and drought conditions.
8 TETRA TECH
More ove r , it i s not anticipated that variation in rainfall would impact the Floridan aquifer over the 21-month timeframe of t he simulation.
Addition a lly , the BOR stipulates that the 1-ft drawdown contour assoc i ate d with the proposed pumping be s imulated and the impacts to existing legal u sers' we ll s within that contour be evaluated.
The process b y which thi s was accompli s h ed is describ ed b e low. 3.3.1 Proposed Salinity Reduction Well Operation There a r e s ix proposed salinity reduction wells. At any one time , five of these well s will collectively pump 14 MOD of low sa linity water from the Upper Floridan aquifer. The s i x we ll s will be space d approximately 1900 ft apart , a l ong the northernm os t canal of t he Cooling Canal System and along the Intercept o r Ditch (Figure 7). In the model , the 14 MGD of pumping i s distributed evenly amongst the five active we ll s and i s assumed to be a constant rate of pumpin g over the cour se of the 25-year s imul ation. Two alternative pumping scena rio s are con s id ered in thi s modeling analysis and differ in the aJJocation of pumping to we l ls F-2 and F-6. The base scenario s imulates pumping at wells F-1 through F-5 (no pumpin g at F-6); the alternative scenario s imulate s pumping at wells F-1 and F-3 through F-6 (no pumping at F-2). The s alinity reduction w e ll s were s imulated , sta rting f rom an equilibrium flow field. A s id e from th ese s alinity reduction we ll s, no pumping was s imulated in thi s m ode l suc h that th e p e rmitted user s w ithin the 1-ft drawdown co ntour could be delineated.
At the conc lu s ion of the 2 1-m o n t h simu l ation, the simu lated drawdowns in the regional model are tho se attributable only to the five proposed sa linit y reduction we ll s. Figure 8a illu s trates these regi o nal drawdowns assoc i ated with the ba se pumping scenario.
In this base s imul a ti o n, the drawd ow n s at a distance from the site are affected by variations in hydraulic c o nductivity; this is evident up o n inspection of the 1-ft drawdown c o ntour , wh i ch generally ha s an oblong s hape , whose m ajo r axis is oriented n oto-south. Nearer to the site, the drawdown contours radiate outward from the wells in a m ore uniform manner , where the maximum drawdown is a pproximately 15.1 ft, near well F-3. In the alternativ e sce nario , the maximum drawdown i s approximate l y 14.4 ft, ne a r well F-5. As previou s ly mentioned , the SFWMD BOR dictate s tbat drawdown at permitted u sers' wells encircled b y the 1-ft drawdown contour be determined.
As illustrated in Figure 8a, the following permitted u se r s fall within the 1-f t drawdown contour: 8 TETRA TECH
* Card Sound Golf Club,
* Card Sound Golf Club,
* Ocean Reef Club,
* Ocean Reef Club,
* the F l o ridan Key s Aqueduct Authorit y (FKAA),
* the F loridan Keys Aqueduct Authority (FKAA),
* Miami-Dade Water a nd Sewage Departm e nt South Miami H eig h ts W e llfield , and
* Miami-Dade Water and Sewage Department South Miami Heights Wellfield, and
* FPL Unit 5 Wells. A second 21-month simulation was conducted wherein pumping by permitted user s and the propo sed sa linit y r e ducti o n we ll s was simulated.
* FPL Unit 5 Wells.
Predicted dra w d ow n s att r i butable so l e ly to permitted Floridan pumpin g were determined by comparing dr awdowns from thi s si mul at ion (Figure 8b) t o those attributabl e to the propo se d sa linit y reduc tio n wells alone (F igure Sa). The s e permitted we ll-ba se d dr aw down s are illu st r a ted in Figure 9 for the ba se pumping sce nari o. Pred icted drawdown s at Floridan well s of the se ex i sting le gal u se r s due to the propo se d operation of the sa linity reduction wells are pre s ented in Table 4. The s e drawdown s are ca lculat ed at the center of the m o del grid cell s in wh i ch the respectiv e w e lls are s imulated.
A second 21-month simulation was conducted wherein pumping by permitted users and the proposed salinity reduction wells was simulated. Predicted drawdowns attributable solely to permitted Floridan pumping were determined by comparing drawdowns from this simulation (Figure 8b) to those attributable to the proposed salinity reduction wells alone (Figure Sa).
In addition to drawdown s attributable to the pr o p ose d wells for the base pumping allocation scenario, cumu l ative drawd ow n s at nearby we ll s due to bot h pumpin g at permitted and proposed we lJ s are provided in Table 4. Withdrawals b y nearb y u s ers we re s im u l a t ed at their re spect i ve permitted r ates. Table 4. Predicted drawdown at nearby users for the proposed Salinity Reducti on Wells due to the base . . pumpmg scenano. Permitted Distance Base Scenar i o Base Scenario Facility Location Withdrawal from Drawdown at Cumulative (L , R , C) we ll F-2 3 , 15, and 21 (MGD) (mi l es) Months (ft) Drawdown (ft) Card Sound Golf (3-Club (WUP 44-0.58 8.8 1.85/2.20/2.21 9.83/1 1.47/1 1.54 00001) 4, 173 ,93) Ocean Reef Club (3-1.42 8.8 1.85/2.20/2.21 9.83/1 1.47/11.54 (WUP 44-00002) 4,173,93)
These permitted well-based drawdowns are illustrated in Figure 9 for the base pumping scenario. Pred icted drawdowns at Floridan wells of these existing legal users due to the proposed operation of the salinity reduction wells are presented in Table 4. These drawdowns are calculated at the center of the model grid cells in which the respective wells are simulated. In addition to drawdowns attributable to the proposed wells for the base pumping allocation scenario, cumu lative drawdowns at nearby wells due to both pumping at permitted and proposed welJs are provided in Table 4. Withdrawals by nearby users were simulated at their respective permitted rates.
FKAA (3-9.70 10.3 1.76/2.15/2.16 416.0 6/17.78/1 7.85 (WUP 13-00005) 4 , 15 5,61) South Miami Ht s (3-4 , 1 33-23.3 10.3 1.83/2.25/2
Table 4. Predicted drawdown at nearby users for the proposed Salinity Reduction Wells due to the base pumpmg scenano.
.26 46.71/48.72/48.80 (WUP 13-00017) 135,79) FPL Un i t 5 Well (3-14.3 < 1.0 11.44/11.85/11.86 34.11/35.92/35.99 (PW-1) 4, 15 6,85) A second eva lu ation was conducted in which the a l ternative pumpin g allocation (wells F-1 and F-3 through F-6) for the sa linit y reduction s wells was simulated.
Distance     Base Scenario Permitted                                        Base Scenario Location                   from       Drawdown at Facility                Withdrawal                                        Cumulative (L,R,C)                 well F-2     3,15, and 21 (MGD)                                         Drawdown (ft)
The re s ulting s im ulated drawdown s at legal user s within the 1-ft drawd ow n co ntour are provided in Table 5; cumu l at i ve drawdown s are a l so tabulated.
(miles)       Months (ft)
In s pection of the drawd ow n s in Table 5 reveals that they a re not s ignific ant l y different from those produced by the b ase pumping allocati on. The cumulative drawdown du e to permitted pumping , as illu s tra te d in Figure 9 , are not s ignifi cantly different than th ose produced by th e c o mbinati o n of pr o p ose d and p e rmi tted withdrawa l s (F igure 8b ). This s ugg es t s that the prop os ed pumpin g of F l oridan water by t he s alinit y reduction we ll s w ill n ot s i g nificantl y exacerbate dr awdow n s in the U pp e r Floridan aquifer beyond tho s e induced by existing permitted pumping. 9 TETRA TECH Tab l e 5. Predicted drawdown at neub y users f or the pr oposed Sa linity Reduction Well s due to the I . . . a ternatlve pumpmg scenano. Alternati v e A lt ernative L oca ti on Distance Scenario Scena r io Facility (L,R,C) from well Drawdown at Cumulat i ve F-2 (miles) 3 , 15, and 21 Months (ft) Drawdown (ft) Card Sou nd Golf Club (3-4, 173 , 93) 8.8 1.86/2.21/2.22 9.84/11.48
Card Sound Golf (3-Club (WUP 44-                   0.58           8.8     1.85/2.20/2.21       9.83/11.47/1 1.54 4, 173,93) 00001)
/11.5 6 (WUP 44-00001)
Ocean Reef Club         (3-1.42           8.8     1.85/2.20/2.21       9.83/1 1.47/11 .54 (WUP 44-00002)     4,173,93)
Ocean Reef Club (3-4, 1 73,93) 8.8 1.86/2.2 1/2.22 9.84/11.48/11.56 (WUP 44-00002)
FKAA             (3-9.70         10.3     1.76/2.15/2. 16   416.06/17.78/1 7.85 (WUP 13-00005)     4, 155,61)
FKAA (3-4, 155 ,6 1) 10.3 1.78/2.17/2.18 16.08/17.80/17.87 (WUP 13-00005)
South Miami Hts    (3-4, 133-23.3         10.3     1.83/2.25/2.26     46.71/48.72/48.80 (WUP 13-00017)       135,79)
South Miami Hts (3-4 , 133-10.3 1.81/2.22/2.24 4 6.6 8/48.69/48.78 (WUP 13-00017) 135,79) FPL Unit 5 Well (PW-1) (3-4 , 15 6,85) < 1.0 9.92/10.33/10.35 32.59/34.40/34.47 4 Conclusions The eva lu ation of drawdown due to pumpin g at the proposed salinity reduc tion wel l s i s ba s ed on th e EC FAS 2 model developed for the SFWMD. This model was s ub se quentl y ada pt e d to sites pecific conditions and re-calibrated to two APTs performed at Turke y Point. The re s ulting regional calibrated groundwate r flow model provides assessment of drawd ow n at nearby existing F l oridan wate r users. In a re g ional s ense, the proposed pumpin g of 1 4 MGD i s projected to result in a maximum Upper Floridan Aq ui fer drawdown rangin g between 14.4 ft (alternative sce nari o) and 15.1 ft (base sce nari o) at the Turkey Point s ite; s imulated drawdowns a t a di stance from Turkey P oint a r e no t s i g nificantly different b etwee n the two pumping s cenario s. The extent of drawdown , as defined by the 1-f t drawdown contour encompas s es four existing leg a l u sers. Overall, the im pacts to offs i te p e rmitted we ll s are minor. The ma x imum drawdown due t o the proposed sa lini ty r e duction we ll s exper i enced by the ne a re st (non-FPL) u se r s i s 2.26 ft and occ ur s at t h e South Miam i Hei g ht s we llfi e ld , loc ated approximate l y 10.3 miles away. Th i s drawdown co mpri ses approximately 4.6% of the cumulativ e drawdown s imul ated at this s it e. The drawdown contribution by the proposed sa linit y reduction we ll s i s a conservative estimate (greater than wou ld actua ll y be experienced), s inc e the drawdown in the wellbore at each n ea rby u se r due to locali ze d pumping i s undersimulated by the coarse-gr idd ed regional model. In add iti on to a demon s tration of minimal dr aw down induc ed at we ll s of permitted u se r s within the 1-ft dr awdow n contour, the BOR a l so st ipulate s that the propo se d pumping n o t impact the sa lt water interface, as defined by the 250 m g/L i soch l or. As the quality of Upper Floridan Aquifer water in this ar ea a lready excee ds s uch a concentrat i on, and no sa ltwat er interface exists, this stip ulation does not apply to the prop osed project. Moreover , the ope r atio n of the sa linity reduc t ion we ll i s not expected impact Upper F l or idan wa ter quality in a regional se n se. Local changes in water qua lit y are expected to b e minor , as demonstrated b y ot h er Upper Floridan water u se r s in t h e re g ion (SFWMD, 20 1 2). 10 TETRA TECH 5 References Anderson, M.P., and Woes s ner , W.W., 199 2, Appl i ed Groundwater Modeling-Sim ul at i on of Flow and Advective Transport:
FPL Unit 5 Well       (3-14.3         < 1.0   11.44/11 .85/11 .86   34.11/35.92/35.99 (PW-1)       4, 156,85)
San Diego, Ca, Academ ic Press, 381 p. Dame s and Moore, 1975. Floridan Aquifer Water Supply Investigation , Turkey Po int Area, Florida. Golder Assoc i ates, 2008. East Coast Floridan Aquifer System Mode l , Pha se 2 , Southeas tern Flor id a, final Model Documentation Report , October 2008, 259pp. Harbaugh , A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-wate r model --Use r guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92 , 121 p. HydroGeoLog ic, 2006. Development of a Den s it y-Dependent Saltwater Intru s i o n Model for the Lower East Coast Project A r ea, April 2006. 166 pp JLA Geosciences, 2006. Well Comp l et i on Report for F l oridan Aquifer Well s PW-1 , PW-3, and PW -4. FPL Turkey Point Expans i o n Project (Unit 5) Homestead, Florida. Langevin, C.D., D.T. Thorne, Jr, A.M. Dau s man , M.C. Sukop, and W. Guo, 2008, SEAWAT Version 4: A Computer Program for S imulation of Mu lti-Species Solute and Heat T r anspor t: USGS Techniques and Methods Book 6, Chapter A22 , 39 p. Sout h F l orida Water Management District (SFWMD), 20 1 2, Overview and Current Use of the Floridan Aquifer System in the Lower East Coast, Public Worksh op, Pompano Beach, F l orida, Apri118, 2012. Z heng , C., and P. Wang, 1 999, MT3DMS , A modular three-dimen siona l multi-species transport model for simulation of advection, dispersion and chemical reac t i ons of contaminants in g roundwater systems; documentation and u se r's guide, U.S. Army E n ginee r Research and Development Cente r Contract Report SERDP-99-1, Vick s bur g, MS, 202 p 11 TETRA TECH P.\FP L\Sali My Reduction\GISIAg1_ModciGrid mxd Legend D Calibration Model Extent D Original Model Extent --Coo ling Canals -Model Grid TITLE: L OCATION; Model Grid Spacing in the Vicinity of Turkey Point for a) Calibrat i on Model and b) Predictive Models Turkey Point, Fl o rida [ 1t:] TETRA TECH 1-C H--Ec::CKC::E=!-P'-'f,:_:A
A second evaluation was conducted in which the a lternative pumping allocation (wells F-1 and F-3 through F-6) for the salinity reductions wells was simulated. The resulting simulated drawdowns at legal users within the 1-ft drawdown contour are provided in Table 5; cumu lative drawdowns are also tabulated. Inspection of the drawdowns in Table 5 reveals that they are not significantly different from those produced by the base pumping allocation.
'------j FIGURE: DRAFTED SCS PROJ 1 17-2826019 1 DATE 031 1 0120 14 
The cumulative drawdown due to permitted pumping, as illustrated in Figure 9, are not significantly different than those produced by the combination of proposed and permitted withdrawals (Figure 8b ). This suggests that the proposed pumping of Floridan water by the salinity reduction wells will not s ignificantly exacerbate drawdowns in the Upper Floridan aquifer beyond those induced by existing permitted pumping.
---7 PW3 I 6 I 0 Simula t ed Drawdown I I -Observed D rawdow n 5 -I -, I J t 1 I II IIIII 0 II I 'II I I 7 OB Sl j 1 1 11 .I I I I 1 I ll Il l I I 1 r 1 I 0 Slmu la l cd D r awdown fl I 6 -II II I II J-ob s Orawdown , I 0 I Ill Ill I II I II I I l l 5 I I I I II I I ll 0 1 2 3 4 5 6 7 g4 I I I I I ll Il l Elapsed Tim e {d) c -o I I I II Ill 3: I 1 Ill 1 7 PW4 J I IJ JJ, I I I 1 I . 0 S imu la ted Orawdown Ill I I II I ,, II II 6 ill II -Observed Orawdown 0 I ill! I I I III I II IIIII 5 -II II II II -1 &#xa3;4 I 0 1 2 3 4 5 6 7 L I ill I I I E l ap s ed Time (d) -o II I I I I 3: IIIII I I I I 1 I II I I I Ill 0 ::r TITLE: Mod eled vs observe d drawdown fo r th e JLA AP T --1 I II I I I II I I 1111 I C alibrate d Adapted Flo ri dan Mode l 0 1 2 3 4 5 6 7 LOCAT IO N: Turkey Point , Florida E l a ps ed T ime (d) CH E C KE D. PFA F I GUR E: [ "R: I TETRA TECH l nRAFTED c JlR 2 FILE: 11 7*2826019 DATE: 031091201 4
9 TETRA TECH
---8 n ow-B Upp er 8 rt ow-B Low er I I 0 Simulated l>rawdo wn 0 Slmula1ed Orawdow n 1-7 7 -Obser v ed O raw down -O bserved Drawdow n 6 I 6 I I I I l/'"*n l I b ""II I I ;E:s ;E:s c , I c I .., II I I I .., g3 3: ,53 II"" !A I""" ..... f\, 2 2 -o o c ) ( ! c 0 h op 1 1 I . I r I I I 0 0 0 20 40 60 80 100 120 0 20 4 0 60 80 100 120 E l apsed Time (d) E l apsed T ime (d) 8 d ow-o Upper I I 8 i ow-o Lower I I I 0 Simula t ed Orawdown I I I O Si mu l lle d O r awdown r 7 I I 7 II I I I
 
* Observed Orawdown I I -Observed Orawdo wn 6 I I 6 I I I I Ill I ;E:s I ;E:s c I I I L I II .., I I I .., I 3: 3: ,53 I I I I I ,53 I I 2 2 I I I I I I . I 1 I 1 -...-nbc '*.1
Table 5. Predicted drawdown at neuby users for the proposed Salinity Reduction Wells due to the a Iternatlve
* o ,s; If. PI *"'r--"Hi .,.. 0 1 0 p O J C ? * . I .. . . I 0 0 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Elapsed Time (d) Elapsed Time (d) nne: Modeled vs observed drawdown fo r the Dames and Moore AP T -Adapted F l oridan Model lOCATION: Turkey Point, Florida CH ECKED: PFA F I GURE* ["11;] T ET R A T E CH ln RAFTEDo L R 3 FI L E: 1 17-28260 1 0 DA TE: 0)109120 1-4 P.\FPL\Salinit)'
                  . pumpmg
Redudron\GIS\Ftg4_Con<A.2.mKd Legend Origin a l Conducti vi ty --Coo li ng Cana l s CJ 3.0E-06 ft/d D 7.5E-05 ft/d D 6.0E-04 ft/d 2.5 E-03 ft/d 9.5E-03 ft/d Calib_rated Conducti vi ty CJ 3.0E-06 ft/d D 6.0E-04 ft/d -1.0 E-03 ft/d 2.5E-03 ft/d 9.5 E-03 ft/d 0 4.5 9 ,...._ __ Scattl n M I H 1 8 I m'bis tribution o f Vertical H yd rau li c Conductiv i ty i n th e Int e rm ediat e Confining Uni t a) Origin al Model, Pr i ortoAddi l ion a l Ca li b r at i on a n d b) After Add i tional Calib rat ion LOCATION: T urkey Poi nt, Florida ( '"ft:) TETRA TECH PROJ 117-2826019 DATE 03/1012014 CHECKE PFA FIGURE: OR A FTEO SCS 4 P.\fPL\Salinit)'
                        . scenano.
R edotfo n'GS\FigS_Condl 3.m xd Legend Original Conductivity D 90 ft/d 725 ft/d 55 ft/d o 224.995 wd n 52 ft/d D 1 oo ftld LJ 3.33 ftld --Coo ling Canals Calibrated Conductivity D 330 ftld D 150 ftld CJ 10 0 ftld 55 ft/d 0 5 10 20 -----Sc al e I n Mi n TITl E: Distributi o n o f Hyd r au li c Conductivity i n the Uppe r F l or i dan Aqui f e r a) Origina l Model, Prior t o Addit i onal C a libr a t i on and b) A ft e r Add i t io na l Ca li b r at io n LOC A T I O N; Turkey Point , Florida 5 [ 1'1:] TETRA TECH I::CH':"E:.::C::KE::f.:-
Alternative A lternative Distance         Scenario Location                                            Scenario Facility                           from well      Drawdown at (L,R,C)                                           Cumulative F-2 (miles)     3,15, and 21 Drawdown (ft)
P O::FA:-------J F I GURE: OR AFTE SCS P R OJ 1 17*28260 19 DATE 0 3/10120 14 P;\F PL\Salinity Redu cti on\GIS\F1g6
Months (ft)
_Coodl6.m x d Legend Original Condu c tivity --Cooling Canals CJ 2.0E-06 ft/d D 2.0E-03 ft/d D 4.0 E-0 3 ft/d 5.0E-03 ft/d D 1.5E-02 ft/d Calibrated Conductivity D 2.0E-0 3 ft/d 3.0E-0 3 ft/d D 4.0E-0 3 ft/d 1.5 E-02 ft/d 8.0 E-02 ft/d D 4.0E-01 ft/d .. _f 0 5 20 ----TITLE: Distrib uti on o f Vert i ca l H y draulic Con d u ctiv ity in t h e M id dl e Co nf i ning U n i t a) Orig i nal Mo de l , P rio r t o A dd it i ona l Calibration and b) Afte r A dd i ti o nal Cali brati o n LOCATION: Tu rkey Point , Florida ( -n:] TETRA TECH CHEC PFA FIG U R E: ORAFTE scs 6 PROJ 117-2826019 OATE 031 1 012014 P: IFPL\Salini!y Reductlon\GIS\NewWells
Card Sound Golf Club (3-4, 173,93)       8.8       1.86/2.21/2.22     9.84/11.48/11 .56 (WUP 44-00001)
_SCA.mxd Legend T ITLE:
Ocean Reef Club (3-4, 173,93)       8.8       1.86/2.21/2. 22   9.84/11.48/11.56 (WUP 44-00002)
* Proposed We ll s LOCATION:
FKAA (3-4, 155,61)       10.3       1.78/2.17/2.18   16.08/17.80/17.87 (WUP 13-00005)
* E x i st ing U nit 5 We ll s F-1 J ----* Location of Proposed Salin i ty Reduction Wells Screened in the U er Flor idan A uifer Tur k e y Point , Flor id a DRAFTED JlR ['A:) TETRA TECH C H ECKE PFA PR O J 117-2826019 D ATE 03/3 1/2014 t 1 F IG URE: 7 P.\FPL\SW'lnity Recmtion'1GI S\Re do n at_OON_21 M o_SCA.mx d Legend
South Miami Hts         (3-4, 133-10.3       1.81 /2.22/2.24   46.68/48.69/48.78 (WUP 13-00017)           135,79)
* Existing User Wells Drawdown Contours (1 ft) 0 5 10 ----
FPL Unit 5 Well (PW-1)     (3-4,156,85)       < 1.0     9.92/10.33/10.35   32.59/34.40/34.47 4   Conclusions The evaluation of drawdown due to pumping at the proposed salinity reduction wel ls is based on the ECFAS2 model developed for the SFWMD. This model was subsequently adapted to site-specific conditions and re-calibrated to two APTs performed at Turkey Point. The resulting regional calibrated groundwater flow model provides assessment of drawdown at nearby existing Floridan water users.
I n Mles TI TlE: LOCA TION: 0 5 10 -----Scat.lnMies a) Pred i cted UFA D r awdown Due to Pro pos ed Wellfie l d, and b) Cumu l ative UFA D ra wd o wn Due to P ermitted and Proposed We llfi e l ds Turkey Point , F lorida CHECK P FA [ -n::) TETRA TECH ORAFTE JLR PROJ 117-2826019 DATE 11/5/2014 FIGURE: 8 P: IFPL\Salinily Reduction'I31S\Permilled _ Q_ DDN _ 21 Mo _ SCAmxd Legend TITLE: --Drawdown Conto ur s LOCATION; --Coo ling Ca n als
In a regional sense, the proposed pumping of 14 MGD is projected to result in a maximum Upper Floridan Aquifer drawdown ranging between 14.4 ft (alternative scenario) and 15.1 ft (base scenario) at the Turkey Point site; simulated drawdowns at a distance from Turkey Point are not significantly different between the two pumping scenarios. The extent of drawdown, as defined by the 1-ft drawdown contour encompasses four existing legal users. Overall, the impacts to off-site permitted wells are minor. The maximum drawdown due to the proposed salinity reduction wells experienced by the nearest (non-FPL) users is 2.26 ft and occurs at the South Miami Heights wellfield, located approximately 10.3 miles away. Th is drawdown comprises approximately 4.6% of the cumulative drawdown simulated at this s ite. The drawdown contribution by the proposed salinity reduction wells is a conservative estimate (greater than would actually be experienced), since the drawdown in the wellbore at each nearby user due to localized pumping is undersimulated by the coarse-gridded regional model.
* Existing User Wells C lub (WUP 44-00002) 0 4 8 16 -----S i mu l ated Equi librium Drawdown in Uppe r Flo ridan Aqui f e r due to Permitted Pumping Tur key Point , Flori da DRAF T ED JLR CH E CKE PFA [ "jl;:) TETRA TECH P RO J 1 17-2826019 D AT E W S/20 1 4 FI G UR E; 9}}
In addition to a demonstration of minimal drawdown induced at wells of permitted users within the 1-ft drawdown contour, the BOR also stipulates that the proposed pumping not impact the saltwater interface, as defined by the 250 mg/L isochlor. As the quality of Upper Floridan Aquifer water in this area already exceeds such a concentration, and no saltwater interface exists, this stipulation does not apply to the proposed project. Moreover, the operation of the salinity reduction well is not expected impact Upper F loridan water quality in a regional sense. Local changes in water quality are expected to be minor, as demonstrated by other Upper Floridan water users in the region (SFWMD, 20 12).
10 TETRA TECH
 
5   References Anderson, M.P., and Woessner, W.W., 1992, Appl ied Groundwater Modeling- Simulation of Flow and Advective Transport: San Diego, Ca, Academ ic Press, 381 p.
Dames and Moore, 1975. Floridan Aquifer Water Supply Investigation, Turkey Po int Area, Florida.
Golder Associates, 2008. East Coast Floridan Aquifer System Model, Phase 2, Southeastern Florida, final Model Documentation Report, October 2008, 259pp.
Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- User guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92, 121 p.
HydroGeoLogic, 2006. Development of a Density-Dependent Saltwater Intrusion Model for the Lower East Coast Project Area, April 2006. 166 pp JLA Geosciences, 2006. Well Completion Report for Floridan Aquifer Wells PW-1 , PW-3, and PW -4. FPL Turkey Point Expansion Project (Unit 5) Homestead, Florida.
Langevin, C.D., D.T. Thorne, Jr, A.M . Dausman, M.C. Sukop, and W. Guo, 2008, SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport: USGS Techniques and Methods Book 6, Chapter A22, 39 p.
South Florida Water Management District (SFWMD), 2012, Overview and Current Use of the Floridan Aquifer System in the Lower East Coast, Public Workshop, Pompano Beach, Florida, Apri118, 2012.
Zheng, C., and P. Wang, 1999, MT3DMS, A modular three-dimensional multi-species transport model for simulation of advection, dispersion and chemical reactions of contaminants in groundwater systems; documentation and user's guide, U.S. Army Engineer Research and Development Center Contract Report SERDP-99-1, Vicksburg, MS, 202 p 11 TETRA TECH
 
P.\FPL\SaliMy Reduction\GISIAg1_ModciGrid mxd Legend                                 TITLE:
Model Grid Spacing in the Vicinity of Turkey Point for a) Calibration Model and b) Predictive Models D        Calibration Model Extent        LOCATION; D        Original Model Extent                                      Turkey Point, Florida
    - - Cooling Canals
    -Model Grid
[1t:]   TETRA TECH 1-CH
                                                                                                --Ec::CKC::E=!-P'-'f,:_:A'----
DRAFTED SCS PROJ DATE 117-2826019 0311012014
                                                                                                                              - -j FIGURE:
1
 
7     PW3
                                          ~
6              I                 I                   0 Simula ted Drawdown I                   I               -     Observed Drawdown 5 -
~4    - ,
                  ~                        I
~3                I                      J t                 1 I II                 IIIII 0
II I                 'II I                               I           7 OB 1
Ill Ill I I 1r1                                                I Slj 1111                              .I I       0 I       I Slmulal cd Drawdown    fl 0        I                                I 6 -
II II                         I II       J-     obs e"':'e~ Orawdown , I Ill Ill      I II I II I Il l                                         5 I                         I II II                  I I ll 0               1     2       3           4       5             6         7 g4 Elapsed Time {d)                                   c
                                                                                      ~3                I                         I II Ill                           Ill
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    -1         I II I             I I             II I                   I 1111 I                   LOCATION:
Calibrated Adapted Floridan Model 0             1     2       3           4         5           6         7                                         Turkey Point, Florida Ela psed Time (d)
I CHECKED. PFA                 FIGURE:
["R: TETRA TECH           lnRAFTEDc FILE:
JlR 117*2826019             2 DATE:   031091201 4
 
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0   Simulated l>rawdown 0   Slmula1ed Orawdown  1-7
                                                                  -     Observed Orawdown                                                                        -       Observed Drawdown I                                                                                         I                   I I I 6                                                                                                6 l/'"*nl I                                         ~~ ~1
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                                                                                                                                                                                ~~
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Modeled vs observed drawdown for the Dames and Moore APT -Adapted Floridan Model lOCATION:
Turkey Point, Florida CH ECKED: PFA                   FIGURE*
["11;] T ETR A T E CH             lnRAFTEDo FILE:
LR 117-2826010            3 DATE:         0)1091201-4
 
P.\FPL\Salinit)' Redudron\GIS\Ftg4_Con<A.2.mKd 0        __
4.5        9 Scattln MIH 18 I
Legend Original Conductivity - - Coo ling Cana ls Calib_rated Conductivity m'bistribution of Vertical Hydraulic Conductivity in the Interm ediate Confining Unit CJ  3.0E-06 ft/d          a) Original Model, PriortoAddilional Calibration a nd b) After Additional Calibration CJ          3.0E-06 ft/d D           7.5E-05 ft/d                   D   6.0E-04 ft/d LOCATION:
Turkey Point, Florida D          6.0E-04 ft/d                   -    1.0E-03 ft/d                                                               CHECKE PFA
('"ft:) TETRA TECH FIGURE:
2.5E-03 ft/d                         2.5E-03 ft/d                                                               ORA FTEO SCS 9.5E-03 ft/d                                                               PROJ      117-2826019      4 9.5E-03 ft/d                                                                                                     DATE      03/1012014
 
P.\fPL\Salinit)' Redotfon'GS\FigS_Condl3.mxd Legend 0          5                  10 Scale In Min 20 TITlE:
Original Conductivity                D  90 ft/d        Calibrated Conductivity          Distribution of Hydraulic Conductivity in the Upper Floridan Aqui fe r a) Original Model, Prior to Additional Calibration and b) After Additional Calibration 725 ft/d                        55 ft/d        D    330 ftld LOCATION; o        224.995 wd                  n   52 ft/d       D   150 ftld                                           Turkey Point, Florida D        1oo ftld                    LJ 3.33 ftld
                                          - - Cooling Canals CJ   100 ftld 55 ft/d
[1'1:] TETRA TECH                            I::CH':"E:.::C::KE::f.:-
ORAFTE PROJ DATE PO::FA:-------J SCS 117*2826019 03/1012014 FIGURE:
5
 
P;\FPL\Salinity Reduction\GIS\F1g6_Coodl6.mxd
_f 0
                                                                                                                        --   -- 5                          20 Legend                                   Calibrated Conductivity Original Conductivity - - Cooling Canals D    2.0E-03 ft/d       TITLE: Distribution of Vertical Hydraulic Conductivity in t he Middle Confining Unit a) Original Model, Prior to Additional Calibration and b) After Additional Calibration CJ 2.0E-06 ft/d                               3.0E-03 ft/d LOCATION:
D 2.0E-03 ft/d                           D   4.0E-03 ft/d                                       Turkey Point, Florida D 4.0E-03 ft/d D
5.0E-03 ft/d 1.5E-02 ft/d                   D 1.5E-02 ft/d 8.0E-02 ft/d 4.0E-01 ft/d
(-n:]      TETRA TECH CHEC ORAFTE PROJ OATE PFA scs 117-2826019 0311012014 FIGURE:
6
 
P:IFPL\Salini!y Reductlon\GIS\NewWells_SCA.mxd t
F-1J 1
Legend TITLE:      Location of Proposed Salinity Reduction Wells
* Proposed Wells                          Screened in the U er Floridan A uifer LOCATION:
* Existing Unit 5 Wells                              Turkey Point, Florida
['A:)  TETRA TECH CHECKE DRAFTED PROJ DATE PFA JlR 117-2826019 03/31/2014 FIGURE:
7
 
P.\FPL\SW'lnity Recmtion'1GIS\Redonat_OON_21Mo_SCA.mxd 0
5    10 Sea~ In Mles 0
                                                                                                                    ---- - 5        10 Scat.lnMies TITlE:
a) Predicted UFA Drawdown Due to Proposed Wellfield, and Legend                                                                    b) Cumulative UFA Drawdown Due to Permitted and Proposed Wellfields
* Existing User Wells                                LOCATION:
Turkey Point, Florida Drawdown Contours (1 ft)
[-n::)
CHECK  PFA            FIGURE:
ORAFTE JLR TETRA TECH                    PROJ    117-2826019      8 DATE    11/5/2014
 
P:IFPL\Salinily Reduction'I31S\Permilled_Q_ DDN_ 21 Mo_ SCAmxd Club (WUP 44-00002) 0
                                                                                                      -- 4
                                                                                                              --   8                16 Legend                                                TITLE:     Simulated Equilibrium Drawdown in Upper Floridan Aquifer
        - - Drawdown Conto urs                                                            due to Permitted Pumping LOCATION;
        - - Coo ling Canals                                                                Turkey Point, Florida CHECKE  PFA        FIGURE;
* Existing User Wells
["jl;:) TETRA TECH                      DRAF TED JLR PROJ    117-2826019   9 DAT E   W S/2014}}

Latest revision as of 07:41, 5 February 2020

FPL-030 - Revised Andersen Memorandum Evaluation of Drawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals, Dated November 13, 2014
ML15314A693
Person / Time
Site: Turkey Point  NextEra Energy icon.png
Issue date: 11/13/2014
From:
Florida Power & Light Co
To:
Atomic Safety and Licensing Board Panel
SECY RAS
References
50-250-LA, 50-251-LA, ASLBP 15-935-02-LA-BD01, RAS 28505
Download: ML15314A693 (20)
v • d • e


Text

FPL-030

(*at:) TETRA TECH TECHNICAL MEMORANDUM From: Peter F. Andersen and James L. Ross, Tetra Tech To: Rory Rahming, Florida Power & Light Company Date: November 13, 2014

Subject:

Evaluation ofDrawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals 1 INTRODUCTION 1.1 Background Florida Power & Light Company (FPL) is in the process of applying for a modification to site certification to reflect the proposed reduction of salinity of cooling canal system (CCS) waters at the Turkey Point Power Plant, located near Florida City, Florida. A component of this project is a series of 1000-1200 foot deep wells that will extract low salinity water from the Upper Floridan Aquifer and discharge it into the CCS for the purpose of reducing the sal inity of CCS water to levels commensurate with Biscayne Bay. As a step in the site certification process, FPL must demonstrate the feasib ility of withdrawing approximately 14 million gallons per day (MGD) of Upper Floridan Aquifer water without adversely impacting the wells of existing legal users of the Floridan Aquifer. This memorandum describes the calibration and simulation of a groundwater flow model of the Floridan Aquifer system that is used to determine potential groundwater level (drawdown) changes resulting from the use of the Floridan Aquifer as a source of water for CCS salinity reduction.

1.2 Scope The scope of this analysis is to calibrate a regional groundwater flow model of the Upper Floridan Aquifer, as defined from regional hydrogeologic data, including two documented Floridan Aquifer Performance Tests (APTs). The modeling shall meet the minimum requirements of the South Florida Water Management District (SFWMD) Basis of Review (BOR) for water use permitting. Once calibrated, the model wi ll be used to evaluate the anticipated drawdown of the Upper Floridan Aquifer potentiometric surface at the plant site and regional settings. The drawdown information will be used to assess the likely impacts to the wells of existing legal users.

1.3 R eport Organization Following this introduction, the memorandum provides a summary of the existing regional groundwater model developed by the SFWMD that was modified andre-calibrated. This existing model is referred to as the East Coast Floridan Aquifer System Model - Phase 2 (ECFAS2). The calibration to the two APTs is then discussed, including changes that were made to the ECF AS2 model and the resulting quality of calibration. Pred ictive regional simulations and corresponding results follow.

2 METHODOLOGY 2.1 Geneml The methodology for conducting this study follows standard groundwater modeling protocols.

As outlined in Anderson and Woessner (1992) the steps involved with model application include:

Definition of purpose

  • Conceptual model development
  • Code selection Model design
  • Calibration I verification
  • Prediction
  • Presentation of results 2.2 Regional Model The primary purpose of the regional model analysis is to assess potential regional drawdown resulting from pumping water from the Upper Floridan Aquifer as a source of low-sal inity water for the CCS. Some of the early steps in the modeling process, most notably conceptual model development, model design, and, to some degree, calibration, were abbreviated in this application because the ECFAS2 model (Golder Associates, 2008) was available to use as the framework for the analysis. The abbreviated relevant steps are summarized in this section. The resulting revised model marks an FPL adaptation to the ECFAS2 model, and is herein referred to as the Adapted Floridan model.

The conceptual model of the natural system is consistent with that described in the existing ECFAS2 model documentation (Golder Associates, 2008). Additional data to modify the hydraulic parameters are available from site specific data collection and testing. Two APTs performed at the site are documented in JLA Geosciences (2006) and Dames and Moore (1975) and serve to supplement the conceptual model presented in the existing ECFAS2 model documentation (Golder Associates, 2008).

The design of the original model was generally unchanged. However, the modeled domain was truncated in the north such that the longitudinal extent of the revised model is less than that of the original. Additionally, the finite difference grid spacing was modified to account for well locations used in the APTs that are simulated in the model re-calibration. Grid modifications are described in Section 3.2. Additionally, since relative changes in flow cond itions (i.e. drawdowns) are the focus of both model calibration and predictions, only the groundwater flow component of the original model is evaluated and employed, herein. Logistically, this decision faci litated efficient model calibration and predictive simulations, as consideration of density-dependent flow and transport resulted in very long run times. The original groundwater flow and transport model was calibrated to regional water levels and saltwater concentrations. To account for site-specific conditions, the model was re-calibrated to two APTs conducted at the site.

2 TETRA TECH

3 Regional Model Simulations 3.1 ECFAS2 Model The SFWMD, through contractors, developed a density-dependent groundwater flow and saltwater transp01t model of the East Coast of F lorida in two phases. The first phase, ECFAS 1 (HydroGeologic, 2006), simulated the southern half of the study area (the Lower East Coast of Florida); the second phase (ECFAS2) expanded the model domain northward to include more of the East Coast of Florida (Golder Associates, 2008). Both phases of the ECFAS model are available from the SFWMD; only the former has been peer-reviewed. Nevertheless, these model s represent the best available framework from which to base a permitting-level analysis of regional Floridan Aquifer impacts resulting from pumping.

The ECFAS2 model encompasses the ECFAS1 region and represents a revision to the earlier work. Consequently, the ECFAS2 model was used as the framework for this analysis. The ECFAS2 model covers the much of the East Coast of Florida, from southern Indian River County to the Florida Keys. This area is discretized into uniform 2400 by 2400 ft cells.

Vertically, the model extends from land surface to the Boulder Zone, a depth of approximately 3000 ft. The vertical section is discretized into 14 layers, with the Upper Floridan Aquifer represented as 2 layers. Boundary conditions are specified to represent flow into and out of the model domain, usually along the perimeter of the study area. Both flow (hydraulic heads) and saltwater transport (TDS concentrations) are simulated and are dependent upon one another (density-dependent flow and transp01t) . Field data from numerous borings were used to establish the structure of the model layering, which represents the hydrostratigraphic layers. In addition, field data from APTs were used to guide the initial choice of hydraulic parameters that were used in the model calibration. The model was calibrated to both hydraulic heads and concentrations.

Even though the model was calibrated, Golder Associates (2008) found that the model 's size resulted in exceptionally long run times such that the scope of the calibration had to be reduced from what was originally envisioned.

3.2 Adapted Floridan Model The ECFAS2 model was not usable in its avai lable state because it covers a very large area and does not provide the resolution required to accurately assess site-specific features and impacts.

Several structural modifications were made to the model and are described herein. Modifications to the calibration of the model are discussed in this section. As previously mentioned, only the groundwater flow capabilities of the ECFAS2 model were germane to the analyses of drawdown described herein, as regional changes in water quality attributable to the proposed wells, as well as the impact of such changes on drawdown, are anticipated to be negligible. Moreover, model run times were dramatically reduced by eliminating the density-dependence.

Since the Adapted Floridan model simulates groundwater flow and is adapted from the SEAWAT-based ECFAS2 model, the USGS simu lation software MODFLOW-2000 (Harbaugh, et al, 2000), a commonly applied groundwater flow model, was used to simulate the regional model. MODFLOW-2000 is capable of addressing the requirements of the SFWMD BOR inasmuch as it:

3 TETRA TECH

  • simulates groundwater flow,
  • is capable of addressing mu ltiple hydrostratigraphic layers and subdividing these layers such that drawdown can be computed at multiple levels within each layer, and
  • is in the public domain, peer-reviewed, and widely used .

The most significant structural change to the model was the grid spacing, which was originally set at 2400 ft. For calibration purposes, the grid was refined in the immediate vicinity of the Turkey Point APTs, such that the well spacing for the APTs could be accurately represented and changes in head over small distances resolved. The revised grid spacing in the model for the calibration is shown in Figure la. The minimum grid spacing used in the Adapted Floridan model, near pumping and monitoring wells, is as little as 1.5 ft. The original model grid spacing, shown in Figut*e lb, was used in subsequent predictive runs because it was adequate for assessment of impacts at the desired scale and was practical from a run-time perspective.

The original model layering was retained because it appeared to be generally appropriate for the level of detail required. The Intermediate Confining Unit (ICU), which overlies the Upper Floridan, was represented using a single layer.

The additional pumping wells that were included as a part of the calibration of the Adapted Floridan model also represent modifications to ECF AS2. The well locations and rates are described in the calibration and model results sections below. The time stepping of the models was also modified to provide adequate resolution for the duration of the APTs and to account for intermittent pumping (Section 3.2.1.1 and 3.2.1.2).

3.2.1 Additional calibration of model Although the ECFAS2 model may represent the regional conditions fai rly well, it may not represent site-specific conditions particularly well. This hypothesis was tested by running the model using documented pumping stresses on the system and comparing the modeled response to that which was observed during the test. In general, as discussed below, the compari son was not good. In order to obtain a reasonable representation of site-specific conditions, two additional calibrations, one to a short-term APT and another to a longer term APT, were performed. The ability to match aquifer system response to these APTs prov ides confidence that the model can predict the response to future proposed pumping. Modeled water levels were checked to ensure that the match to regional calibration targets had not been degraded as a result of the local changes. The methodology and resu lts of each of the additional calibrations are described below.

3.2.1 .1 JLA APT JLA Geosciences (2006) conducted an APT in support of the Unit 5 site certification. Floridan water supply well PW-1 was pumped for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and drawdown was measured in two other water supply wells and a shallow observation well. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibration because it was local to the area of proposed pumping and was conducted under quality-controlled conditions. However, it was recognized that the short duration of the test and extent of monitoring points would provide data that may only be representative of a relatively small area.

4 TETRA TECH

Simulation of the APT was accomplished using the revised model grid. Well PW -1 was represented with a single well pumping at a rate of 4500 gpm in model layers 3 and 4, which represent the Upper Floridan Aquifer, in the cell at row 166, column 143 Timestepping ranged from a minimum of 5 to a maximum of 567 minutes, Drawdown response was noted in wells PW-3 (layers 3 and 4, row 168, column 171), PW-4 (layers 3 and 4, row 180, column 157), and OBS-1 (layer 2, row 166, column 143) at distances of 3036, 1686, and 0 feet, respectively from the pumped well. Note that OBS-1 is co-located with the pumping we ll , but is screened near the base of the Biscayne Aquifer and did not experience drawdown in response to the APT.

Comparison of modeled to observed conditions for the original model, prior to adjustment, was not good, with a residual standard deviation of greater than 100 ft. However, as shown in F igure 2, this match improved cons iderably (residual standard deviation of 0.36 ft) after adjustment of hydraulic parameters as a pmt of the calibration. In general, hydraulic conductivities were increased from their original values during calibration. Goodness-of-fit ca libration metrics are shown in Table 1 and indicate that the model provides a reasonable fit to observed data.

Table 1. Goodness of fit metrics for the JLA APT calibration Metric Numerical Value Mean Error, ft 0.22 Mean Absolute Error, ft 0.33 Residual Standard Deviation, ft 0.36 Range of Targ_ets , ft 6.36 Residual Standard Deviation I Range *100 5.6%

Note that this calibration was conducted iteratively with the Dames and Moore APT described below and hence the calibrations strike a balance between matching the results of both APTs with the same set of parameters.

3.2.1.2 Dames and Moore APT Dames and Moore (1975) conducted an APT in support of a feasibility study for using Floridan Aquifer water to cool the original Turkey Point nuclear units. Floridan Aquifer production test well (PTW) was pumped for 90 days and drawdown was measured in eight monitoring wells at various distances from the pumped well and depths in the aquifer. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibrati on because of its long duration and use of monitoring points that were distant from the pumping well. Thus, this test was complementary to the shorter duration, more local JLA APT described above.

As in the simulation of the JLA APT, the simulation of the Dames and Moore APT was accomplished using the refined model grid. Well PTW was represented with a single well pumping at a rate of 5000 gpm in cell layers 3 and 4, row 220, and column 97. Timestepping ranged from a minimum of 73 minutes to a maximum of 11.8 days. Drawdown response was noted in wells OW-A (row 229, column 108), OW-B (row 238, column 120), OW-C (row 207,column 82), and OW-D (row 258, co lumn 181) at distances of 100 feet, 500 feet, 2000 feet, and 48,000 feet, respectively from the pumped well. Drawdown was recorded in the Upper and Middle Floridan aquifers at each of the four observation well sites, which are represented by layers 3 and 4, and 7 and 8, respectively 5

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Comparison of modeled to observed conditions for the original model, prio r to adjustment, was not good (residual standard deviation in excess of I 0 ft), as was the case for the JLA APT. As shown in Figure 3, this match also improved considerably (with a residual standard deviation of 0.77 ft) after adjustment of hydraulic parameters as a part of the calibration. Goodness-of-fit calibration metrics are shown in Table 2 and indicate that the model provides a reasonable fit to observed data.

Table 2. Goodness of fit mctrics fo1* the Dames and Moore APT calibration Metric Numerical Value Mean Error, ft -0.30 Mean Absolute Error, ft 0.66 Residual Standard Deviation, ft 0.77 Range of Targets, ft 11.8 Residual Standard Deviation I Range

  • 100 6.5%

Though the wells shown in Figure 3 are not an exhaustive representation of the calibration targets, they are a microcosm of the quality of the model match to this APT. The lateral and vertical proximity to the pumping well precluded a reasonable match to the observed drawdown at well OW-A (Upper); as such, this well was omitted from the calibration.

3.2.1.3 Adjustments to the calibration The primary parameters that were changed as a result of the additional calibration were hydraulic conductivities of the Upper Floridan Aquifer (UFA), ICU, Middle Confining Unit (MCU), and the Middle Floridan Aquifer (MFA). These parameters were all raised from their orig inal values, as shown in Table 3.

Note that the parameter changes were made within zones that were near the Turkey Point site and mostly in areas potentially affected by drawdown from proposed salinity reduction wells, as shown in Figure 4, 5, and 6.

The changes made to the hydra ulic properties in the Adapted Floridan model are not expected to significantly impact the quality of the model match to the water level and water quality targets employed in the calibration of the ECF AS2 model. The changes made to the Adapted Floridan model were generally minor, and the preponderance of the ECFAS2 model calibration targets are located outside of the Adapted Floridan model doma in. Water levels at well ENP-100, located about 17 miles to west of Turkey Point, were simulated to be approximately 36ft, which slightl y underestimates observed water levels (approximately 37.5 ft NGVD29). The ECFAS2 model si mulates a water level of 39 feet at this location, after 350 days of simulation. Simulated water levels at W ASA-South, located to the n011h of Turkey Point, are approximately 35 ft NGVD 29; this well, however, was omitted from the ECFAS2 modeling analysis due to anomalous water levels (Golder Associates, 2008).

6 TETRA TECH

Tablc3 P arameter c 1anges resu I tmg

. f rom ca J'b 1 ration o f t I1c Ad apted Flone

'I an mo d e.I ECFAS2 model FPL Floridan Model Hydrologic Model Aquifer (original) (recalibrated)

Unit Layers Parameter magnitude magnitude 0.0006 0.001 Kz (fUd)

ICU 2 0.000075 0.001 Kh (fUd) 0.000075 0.001 5.2 100 Kz (fUd) 9 15 72.5 225 0.33 225 UFA 3,4 52 100 Kh (ft/d) 90 150 725 330 3.33 330 Ss 5.25E-07 8.00E-07 0.004 0.003 0.000002 0.08 Kz (fUd) 0.4 0.003 MCU 5,6 0.002 0.08 0.02 0.08 Kh (fUd) 0.00001 0.4 0.03 Kz (fUd) 5.2 30 450 900 MFA 7,8 300 600 Kh (fUd) 180 1200 52 600 0.0015 0.01 MC2 9,10,11 Kz (ft/d) 0.0002 0.02 3.3 Predictive Simulations Once calibration of the regional Floridan model was confirmed, equilibrium flow conditions were established by running the model, holding all flow boundaries (e.g. specified heads) constant until changes in the simulated flow field in the Florida n Aquifer System were negligible. No pumping was simulated in this equi librium model. The resulting equilibrated state formed the initial conditions for ensuing predictive simulations. Equilibrated regional water 7

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levels, especially near Turkey Point, were generally lower than observed water levels; this is due to the exclusion of salt transport and the associated density-dependent flow. However, given that purpose of th is model is to provide estimates of relative changes in water level , the low simulated water levels were deemed irrelevant. Since the focus of the salinity reduction well evaluation is regional drawdown, the original 2400-ft grid spacing was employed for predictive simulations.

According the SFWMD BOR, predictive evaluations made with the calibrated model must be conducted using monthly stress periods that simulate average annual groundwater withdrawals subject to rainfall that alternates between average and 1-in-1 0 year draught conditions (3 months of average cond itions, followed by 12 months of drought conditions, followed by 6 months of average conditions). As such, the predictive models were conducted using 21 monthly stress periods .. Due to the specified head boundary in the topmost layer of the model, climatic stressess were not varied between average and drought conditions. Moreover, it is not anticipated that variation in rainfall would impact the Floridan aquifer over the 21-month timeframe of the simulation.

Additionally, the BOR stipulates that the 1-ft drawdown contour associated with the proposed pumping be simulated and the impacts to existing legal users' wells within that contour be evaluated. The process by which this was accomplished is described below.

3.3.1 Proposed Salinity Reduction Well Operation There are six proposed salinity reduction wells. At any one time, five of these well s will collectively pump 14 MOD of low salinity water from the Upper Floridan aquifer. The six wells will be spaced approximately 1900 ft apart, along the northernmost canal of the Cooling Canal System and along the Interceptor Ditch (Figure 7). In the model , the 14 MGD of pumping is distributed evenly amongst the five active wells and is assumed to be a constant rate of pumping over the course of the 25-year simulation. Two alternative pumping scenarios are considered in this modeling analysis and differ in the aJJocation of pumping to wells F-2 and F-6. The base scenario simulates pumping at wells F-1 through F-5 (no pumping at F-6); the alternative scenario simulates pumping at wells F-1 and F-3 through F-6 (no pumping at F-2).

The salinity reduction wells were simulated, starting from an equilibrium flow field. Aside from these salinity reduction wells, no pumping was simulated in this model such that the permitted users w ithin the 1-ft drawdown contour could be delineated. At the conclusion of the 21-month simu lation, the simulated drawdowns in the regional model are those attributable only to the five proposed salinity reduction wells. Figure 8a illustrates these regional drawdowns associated with the base pumping scenario. In this base simulation, the drawdowns at a distance from the site are affected by variations in hydraulic conductivity; this is evident upon inspection of the 1-ft drawdown contour, wh ich generally has an oblong shape, whose major axis is oriented north-to-south . Nearer to the site, the drawdown contours radiate outward from the wells in a more uniform manner, where the maximum drawdown is approximately 15.1 ft, near well F-3. In the alternative scenario, the maximum drawdown is approximately 14.4 ft, near well F-5.

As previously mentioned, the SFWMD BOR dictates tbat drawdown at permitted users' wells encircled by the 1-ft drawdown contour be determined. As illustrated in Figure 8a, the following permitted users fall within the 1-ft drawdown contour:

8 TETRA TECH

  • Card Sound Golf Club,
  • Ocean Reef Club,
  • the F loridan Keys Aqueduct Authority (FKAA),
  • Miami-Dade Water and Sewage Department South Miami Heights Wellfield, and
  • FPL Unit 5 Wells.

A second 21-month simulation was conducted wherein pumping by permitted users and the proposed salinity reduction wells was simulated. Predicted drawdowns attributable solely to permitted Floridan pumping were determined by comparing drawdowns from this simulation (Figure 8b) to those attributable to the proposed salinity reduction wells alone (Figure Sa).

These permitted well-based drawdowns are illustrated in Figure 9 for the base pumping scenario. Pred icted drawdowns at Floridan wells of these existing legal users due to the proposed operation of the salinity reduction wells are presented in Table 4. These drawdowns are calculated at the center of the model grid cells in which the respective wells are simulated. In addition to drawdowns attributable to the proposed wells for the base pumping allocation scenario, cumu lative drawdowns at nearby wells due to both pumping at permitted and proposed welJs are provided in Table 4. Withdrawals by nearby users were simulated at their respective permitted rates.

Table 4. Predicted drawdown at nearby users for the proposed Salinity Reduction Wells due to the base pumpmg scenano.

Distance Base Scenario Permitted Base Scenario Location from Drawdown at Facility Withdrawal Cumulative (L,R,C) well F-2 3,15, and 21 (MGD) Drawdown (ft)

(miles) Months (ft)

Card Sound Golf (3-Club (WUP 44- 0.58 8.8 1.85/2.20/2.21 9.83/11.47/1 1.54 4, 173,93) 00001)

Ocean Reef Club (3-1.42 8.8 1.85/2.20/2.21 9.83/1 1.47/11 .54 (WUP 44-00002) 4,173,93)

FKAA (3-9.70 10.3 1.76/2.15/2. 16 416.06/17.78/1 7.85 (WUP 13-00005) 4, 155,61)

South Miami Hts (3-4, 133-23.3 10.3 1.83/2.25/2.26 46.71/48.72/48.80 (WUP 13-00017) 135,79)

FPL Unit 5 Well (3-14.3 < 1.0 11.44/11 .85/11 .86 34.11/35.92/35.99 (PW-1) 4, 156,85)

A second evaluation was conducted in which the a lternative pumping allocation (wells F-1 and F-3 through F-6) for the salinity reductions wells was simulated. The resulting simulated drawdowns at legal users within the 1-ft drawdown contour are provided in Table 5; cumu lative drawdowns are also tabulated. Inspection of the drawdowns in Table 5 reveals that they are not significantly different from those produced by the base pumping allocation.

The cumulative drawdown due to permitted pumping, as illustrated in Figure 9, are not significantly different than those produced by the combination of proposed and permitted withdrawals (Figure 8b ). This suggests that the proposed pumping of Floridan water by the salinity reduction wells will not s ignificantly exacerbate drawdowns in the Upper Floridan aquifer beyond those induced by existing permitted pumping.

9 TETRA TECH

Table 5. Predicted drawdown at neuby users for the proposed Salinity Reduction Wells due to the a Iternatlve

. pumpmg

. scenano.

Alternative A lternative Distance Scenario Location Scenario Facility from well Drawdown at (L,R,C) Cumulative F-2 (miles) 3,15, and 21 Drawdown (ft)

Months (ft)

Card Sound Golf Club (3-4, 173,93) 8.8 1.86/2.21/2.22 9.84/11.48/11 .56 (WUP 44-00001)

Ocean Reef Club (3-4, 173,93) 8.8 1.86/2.21/2. 22 9.84/11.48/11.56 (WUP 44-00002)

FKAA (3-4, 155,61) 10.3 1.78/2.17/2.18 16.08/17.80/17.87 (WUP 13-00005)

South Miami Hts (3-4, 133-10.3 1.81 /2.22/2.24 46.68/48.69/48.78 (WUP 13-00017) 135,79)

FPL Unit 5 Well (PW-1) (3-4,156,85) < 1.0 9.92/10.33/10.35 32.59/34.40/34.47 4 Conclusions The evaluation of drawdown due to pumping at the proposed salinity reduction wel ls is based on the ECFAS2 model developed for the SFWMD. This model was subsequently adapted to site-specific conditions and re-calibrated to two APTs performed at Turkey Point. The resulting regional calibrated groundwater flow model provides assessment of drawdown at nearby existing Floridan water users.

In a regional sense, the proposed pumping of 14 MGD is projected to result in a maximum Upper Floridan Aquifer drawdown ranging between 14.4 ft (alternative scenario) and 15.1 ft (base scenario) at the Turkey Point site; simulated drawdowns at a distance from Turkey Point are not significantly different between the two pumping scenarios. The extent of drawdown, as defined by the 1-ft drawdown contour encompasses four existing legal users. Overall, the impacts to off-site permitted wells are minor. The maximum drawdown due to the proposed salinity reduction wells experienced by the nearest (non-FPL) users is 2.26 ft and occurs at the South Miami Heights wellfield, located approximately 10.3 miles away. Th is drawdown comprises approximately 4.6% of the cumulative drawdown simulated at this s ite. The drawdown contribution by the proposed salinity reduction wells is a conservative estimate (greater than would actually be experienced), since the drawdown in the wellbore at each nearby user due to localized pumping is undersimulated by the coarse-gridded regional model.

In addition to a demonstration of minimal drawdown induced at wells of permitted users within the 1-ft drawdown contour, the BOR also stipulates that the proposed pumping not impact the saltwater interface, as defined by the 250 mg/L isochlor. As the quality of Upper Floridan Aquifer water in this area already exceeds such a concentration, and no saltwater interface exists, this stipulation does not apply to the proposed project. Moreover, the operation of the salinity reduction well is not expected impact Upper F loridan water quality in a regional sense. Local changes in water quality are expected to be minor, as demonstrated by other Upper Floridan water users in the region (SFWMD, 20 12).

10 TETRA TECH

5 References Anderson, M.P., and Woessner, W.W., 1992, Appl ied Groundwater Modeling- Simulation of Flow and Advective Transport: San Diego, Ca, Academ ic Press, 381 p.

Dames and Moore, 1975. Floridan Aquifer Water Supply Investigation, Turkey Po int Area, Florida.

Golder Associates, 2008. East Coast Floridan Aquifer System Model, Phase 2, Southeastern Florida, final Model Documentation Report, October 2008, 259pp.

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- User guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92, 121 p.

HydroGeoLogic, 2006. Development of a Density-Dependent Saltwater Intrusion Model for the Lower East Coast Project Area, April 2006. 166 pp JLA Geosciences, 2006. Well Completion Report for Floridan Aquifer Wells PW-1 , PW-3, and PW -4. FPL Turkey Point Expansion Project (Unit 5) Homestead, Florida.

Langevin, C.D., D.T. Thorne, Jr, A.M . Dausman, M.C. Sukop, and W. Guo, 2008, SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport: USGS Techniques and Methods Book 6, Chapter A22, 39 p.

South Florida Water Management District (SFWMD), 2012, Overview and Current Use of the Floridan Aquifer System in the Lower East Coast, Public Workshop, Pompano Beach, Florida, Apri118, 2012.

Zheng, C., and P. Wang, 1999, MT3DMS, A modular three-dimensional multi-species transport model for simulation of advection, dispersion and chemical reactions of contaminants in groundwater systems; documentation and user's guide, U.S. Army Engineer Research and Development Center Contract Report SERDP-99-1, Vicksburg, MS, 202 p 11 TETRA TECH

P.\FPL\SaliMy Reduction\GISIAg1_ModciGrid mxd Legend TITLE:

Model Grid Spacing in the Vicinity of Turkey Point for a) Calibration Model and b) Predictive Models D Calibration Model Extent LOCATION; D Original Model Extent Turkey Point, Florida

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('"ft:) TETRA TECH FIGURE:

2.5E-03 ft/d 2.5E-03 ft/d ORA FTEO SCS 9.5E-03 ft/d PROJ 117-2826019 4 9.5E-03 ft/d DATE 03/1012014

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Original Conductivity D 90 ft/d Calibrated Conductivity Distribution of Hydraulic Conductivity in the Upper Floridan Aqui fe r a) Original Model, Prior to Additional Calibration and b) After Additional Calibration 725 ft/d 55 ft/d D 330 ftld LOCATION; o 224.995 wd n 52 ft/d D 150 ftld Turkey Point, Florida D 1oo ftld LJ 3.33 ftld

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['A:) TETRA TECH CHECKE DRAFTED PROJ DATE PFA JlR 117-2826019 03/31/2014 FIGURE:

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Turkey Point, Florida Drawdown Contours (1 ft)

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["jl;:) TETRA TECH DRAF TED JLR PROJ 117-2826019 9 DAT E W S/2014

FPL-030

(*at:) TETRA TECH TECHNICAL MEMORANDUM From: Peter F. Andersen and James L. Ross, Tetra Tech To: Rory Rahming, Florida Power & Light Company Date: November 13, 2014

Subject:

Evaluation ofDrawdown in the Upper Floridan Aquifer Due to Proposed Salinity Reduction-based Withdrawals 1 INTRODUCTION 1.1 Background Florida Power & Light Company (FPL) is in the process of applying for a modification to site certification to reflect the proposed reduction of salinity of cooling canal system (CCS) waters at the Turkey Point Power Plant, located near Florida City, Florida. A component of this project is a series of 1000-1200 foot deep wells that will extract low salinity water from the Upper Floridan Aquifer and discharge it into the CCS for the purpose of reducing the sal inity of CCS water to levels commensurate with Biscayne Bay. As a step in the site certification process, FPL must demonstrate the feasib ility of withdrawing approximately 14 million gallons per day (MGD) of Upper Floridan Aquifer water without adversely impacting the wells of existing legal users of the Floridan Aquifer. This memorandum describes the calibration and simulation of a groundwater flow model of the Floridan Aquifer system that is used to determine potential groundwater level (drawdown) changes resulting from the use of the Floridan Aquifer as a source of water for CCS salinity reduction.

1.2 Scope The scope of this analysis is to calibrate a regional groundwater flow model of the Upper Floridan Aquifer, as defined from regional hydrogeologic data, including two documented Floridan Aquifer Performance Tests (APTs). The modeling shall meet the minimum requirements of the South Florida Water Management District (SFWMD) Basis of Review (BOR) for water use permitting. Once calibrated, the model wi ll be used to evaluate the anticipated drawdown of the Upper Floridan Aquifer potentiometric surface at the plant site and regional settings. The drawdown information will be used to assess the likely impacts to the wells of existing legal users.

1.3 R eport Organization Following this introduction, the memorandum provides a summary of the existing regional groundwater model developed by the SFWMD that was modified andre-calibrated. This existing model is referred to as the East Coast Floridan Aquifer System Model - Phase 2 (ECFAS2). The calibration to the two APTs is then discussed, including changes that were made to the ECF AS2 model and the resulting quality of calibration. Pred ictive regional simulations and corresponding results follow.

2 METHODOLOGY 2.1 Geneml The methodology for conducting this study follows standard groundwater modeling protocols.

As outlined in Anderson and Woessner (1992) the steps involved with model application include:

Definition of purpose

  • Conceptual model development
  • Code selection Model design
  • Calibration I verification
  • Prediction
  • Presentation of results 2.2 Regional Model The primary purpose of the regional model analysis is to assess potential regional drawdown resulting from pumping water from the Upper Floridan Aquifer as a source of low-sal inity water for the CCS. Some of the early steps in the modeling process, most notably conceptual model development, model design, and, to some degree, calibration, were abbreviated in this application because the ECFAS2 model (Golder Associates, 2008) was available to use as the framework for the analysis. The abbreviated relevant steps are summarized in this section. The resulting revised model marks an FPL adaptation to the ECFAS2 model, and is herein referred to as the Adapted Floridan model.

The conceptual model of the natural system is consistent with that described in the existing ECFAS2 model documentation (Golder Associates, 2008). Additional data to modify the hydraulic parameters are available from site specific data collection and testing. Two APTs performed at the site are documented in JLA Geosciences (2006) and Dames and Moore (1975) and serve to supplement the conceptual model presented in the existing ECFAS2 model documentation (Golder Associates, 2008).

The design of the original model was generally unchanged. However, the modeled domain was truncated in the north such that the longitudinal extent of the revised model is less than that of the original. Additionally, the finite difference grid spacing was modified to account for well locations used in the APTs that are simulated in the model re-calibration. Grid modifications are described in Section 3.2. Additionally, since relative changes in flow cond itions (i.e. drawdowns) are the focus of both model calibration and predictions, only the groundwater flow component of the original model is evaluated and employed, herein. Logistically, this decision faci litated efficient model calibration and predictive simulations, as consideration of density-dependent flow and transport resulted in very long run times. The original groundwater flow and transport model was calibrated to regional water levels and saltwater concentrations. To account for site-specific conditions, the model was re-calibrated to two APTs conducted at the site.

2 TETRA TECH

3 Regional Model Simulations 3.1 ECFAS2 Model The SFWMD, through contractors, developed a density-dependent groundwater flow and saltwater transp01t model of the East Coast of F lorida in two phases. The first phase, ECFAS 1 (HydroGeologic, 2006), simulated the southern half of the study area (the Lower East Coast of Florida); the second phase (ECFAS2) expanded the model domain northward to include more of the East Coast of Florida (Golder Associates, 2008). Both phases of the ECFAS model are available from the SFWMD; only the former has been peer-reviewed. Nevertheless, these model s represent the best available framework from which to base a permitting-level analysis of regional Floridan Aquifer impacts resulting from pumping.

The ECFAS2 model encompasses the ECFAS1 region and represents a revision to the earlier work. Consequently, the ECFAS2 model was used as the framework for this analysis. The ECFAS2 model covers the much of the East Coast of Florida, from southern Indian River County to the Florida Keys. This area is discretized into uniform 2400 by 2400 ft cells.

Vertically, the model extends from land surface to the Boulder Zone, a depth of approximately 3000 ft. The vertical section is discretized into 14 layers, with the Upper Floridan Aquifer represented as 2 layers. Boundary conditions are specified to represent flow into and out of the model domain, usually along the perimeter of the study area. Both flow (hydraulic heads) and saltwater transport (TDS concentrations) are simulated and are dependent upon one another (density-dependent flow and transp01t) . Field data from numerous borings were used to establish the structure of the model layering, which represents the hydrostratigraphic layers. In addition, field data from APTs were used to guide the initial choice of hydraulic parameters that were used in the model calibration. The model was calibrated to both hydraulic heads and concentrations.

Even though the model was calibrated, Golder Associates (2008) found that the model 's size resulted in exceptionally long run times such that the scope of the calibration had to be reduced from what was originally envisioned.

3.2 Adapted Floridan Model The ECFAS2 model was not usable in its avai lable state because it covers a very large area and does not provide the resolution required to accurately assess site-specific features and impacts.

Several structural modifications were made to the model and are described herein. Modifications to the calibration of the model are discussed in this section. As previously mentioned, only the groundwater flow capabilities of the ECFAS2 model were germane to the analyses of drawdown described herein, as regional changes in water quality attributable to the proposed wells, as well as the impact of such changes on drawdown, are anticipated to be negligible. Moreover, model run times were dramatically reduced by eliminating the density-dependence.

Since the Adapted Floridan model simulates groundwater flow and is adapted from the SEAWAT-based ECFAS2 model, the USGS simu lation software MODFLOW-2000 (Harbaugh, et al, 2000), a commonly applied groundwater flow model, was used to simulate the regional model. MODFLOW-2000 is capable of addressing the requirements of the SFWMD BOR inasmuch as it:

3 TETRA TECH

  • simulates groundwater flow,
  • is capable of addressing mu ltiple hydrostratigraphic layers and subdividing these layers such that drawdown can be computed at multiple levels within each layer, and
  • is in the public domain, peer-reviewed, and widely used .

The most significant structural change to the model was the grid spacing, which was originally set at 2400 ft. For calibration purposes, the grid was refined in the immediate vicinity of the Turkey Point APTs, such that the well spacing for the APTs could be accurately represented and changes in head over small distances resolved. The revised grid spacing in the model for the calibration is shown in Figure la. The minimum grid spacing used in the Adapted Floridan model, near pumping and monitoring wells, is as little as 1.5 ft. The original model grid spacing, shown in Figut*e lb, was used in subsequent predictive runs because it was adequate for assessment of impacts at the desired scale and was practical from a run-time perspective.

The original model layering was retained because it appeared to be generally appropriate for the level of detail required. The Intermediate Confining Unit (ICU), which overlies the Upper Floridan, was represented using a single layer.

The additional pumping wells that were included as a part of the calibration of the Adapted Floridan model also represent modifications to ECF AS2. The well locations and rates are described in the calibration and model results sections below. The time stepping of the models was also modified to provide adequate resolution for the duration of the APTs and to account for intermittent pumping (Section 3.2.1.1 and 3.2.1.2).

3.2.1 Additional calibration of model Although the ECFAS2 model may represent the regional conditions fai rly well, it may not represent site-specific conditions particularly well. This hypothesis was tested by running the model using documented pumping stresses on the system and comparing the modeled response to that which was observed during the test. In general, as discussed below, the compari son was not good. In order to obtain a reasonable representation of site-specific conditions, two additional calibrations, one to a short-term APT and another to a longer term APT, were performed. The ability to match aquifer system response to these APTs prov ides confidence that the model can predict the response to future proposed pumping. Modeled water levels were checked to ensure that the match to regional calibration targets had not been degraded as a result of the local changes. The methodology and resu lts of each of the additional calibrations are described below.

3.2.1 .1 JLA APT JLA Geosciences (2006) conducted an APT in support of the Unit 5 site certification. Floridan water supply well PW-1 was pumped for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and drawdown was measured in two other water supply wells and a shallow observation well. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibration because it was local to the area of proposed pumping and was conducted under quality-controlled conditions. However, it was recognized that the short duration of the test and extent of monitoring points would provide data that may only be representative of a relatively small area.

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Simulation of the APT was accomplished using the revised model grid. Well PW -1 was represented with a single well pumping at a rate of 4500 gpm in model layers 3 and 4, which represent the Upper Floridan Aquifer, in the cell at row 166, column 143 Timestepping ranged from a minimum of 5 to a maximum of 567 minutes, Drawdown response was noted in wells PW-3 (layers 3 and 4, row 168, column 171), PW-4 (layers 3 and 4, row 180, column 157), and OBS-1 (layer 2, row 166, column 143) at distances of 3036, 1686, and 0 feet, respectively from the pumped well. Note that OBS-1 is co-located with the pumping we ll , but is screened near the base of the Biscayne Aquifer and did not experience drawdown in response to the APT.

Comparison of modeled to observed conditions for the original model, prior to adjustment, was not good, with a residual standard deviation of greater than 100 ft. However, as shown in F igure 2, this match improved cons iderably (residual standard deviation of 0.36 ft) after adjustment of hydraulic parameters as a pmt of the calibration. In general, hydraulic conductivities were increased from their original values during calibration. Goodness-of-fit ca libration metrics are shown in Table 1 and indicate that the model provides a reasonable fit to observed data.

Table 1. Goodness of fit metrics for the JLA APT calibration Metric Numerical Value Mean Error, ft 0.22 Mean Absolute Error, ft 0.33 Residual Standard Deviation, ft 0.36 Range of Targ_ets , ft 6.36 Residual Standard Deviation I Range *100 5.6%

Note that this calibration was conducted iteratively with the Dames and Moore APT described below and hence the calibrations strike a balance between matching the results of both APTs with the same set of parameters.

3.2.1.2 Dames and Moore APT Dames and Moore (1975) conducted an APT in support of a feasibility study for using Floridan Aquifer water to cool the original Turkey Point nuclear units. Floridan Aquifer production test well (PTW) was pumped for 90 days and drawdown was measured in eight monitoring wells at various distances from the pumped well and depths in the aquifer. The drawdown response documented during this test was believed to represent a good series of targets to match as a part of a calibrati on because of its long duration and use of monitoring points that were distant from the pumping well. Thus, this test was complementary to the shorter duration, more local JLA APT described above.

As in the simulation of the JLA APT, the simulation of the Dames and Moore APT was accomplished using the refined model grid. Well PTW was represented with a single well pumping at a rate of 5000 gpm in cell layers 3 and 4, row 220, and column 97. Timestepping ranged from a minimum of 73 minutes to a maximum of 11.8 days. Drawdown response was noted in wells OW-A (row 229, column 108), OW-B (row 238, column 120), OW-C (row 207,column 82), and OW-D (row 258, co lumn 181) at distances of 100 feet, 500 feet, 2000 feet, and 48,000 feet, respectively from the pumped well. Drawdown was recorded in the Upper and Middle Floridan aquifers at each of the four observation well sites, which are represented by layers 3 and 4, and 7 and 8, respectively 5

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Comparison of modeled to observed conditions for the original model, prio r to adjustment, was not good (residual standard deviation in excess of I 0 ft), as was the case for the JLA APT. As shown in Figure 3, this match also improved considerably (with a residual standard deviation of 0.77 ft) after adjustment of hydraulic parameters as a part of the calibration. Goodness-of-fit calibration metrics are shown in Table 2 and indicate that the model provides a reasonable fit to observed data.

Table 2. Goodness of fit mctrics fo1* the Dames and Moore APT calibration Metric Numerical Value Mean Error, ft -0.30 Mean Absolute Error, ft 0.66 Residual Standard Deviation, ft 0.77 Range of Targets, ft 11.8 Residual Standard Deviation I Range

  • 100 6.5%

Though the wells shown in Figure 3 are not an exhaustive representation of the calibration targets, they are a microcosm of the quality of the model match to this APT. The lateral and vertical proximity to the pumping well precluded a reasonable match to the observed drawdown at well OW-A (Upper); as such, this well was omitted from the calibration.

3.2.1.3 Adjustments to the calibration The primary parameters that were changed as a result of the additional calibration were hydraulic conductivities of the Upper Floridan Aquifer (UFA), ICU, Middle Confining Unit (MCU), and the Middle Floridan Aquifer (MFA). These parameters were all raised from their orig inal values, as shown in Table 3.

Note that the parameter changes were made within zones that were near the Turkey Point site and mostly in areas potentially affected by drawdown from proposed salinity reduction wells, as shown in Figure 4, 5, and 6.

The changes made to the hydra ulic properties in the Adapted Floridan model are not expected to significantly impact the quality of the model match to the water level and water quality targets employed in the calibration of the ECF AS2 model. The changes made to the Adapted Floridan model were generally minor, and the preponderance of the ECFAS2 model calibration targets are located outside of the Adapted Floridan model doma in. Water levels at well ENP-100, located about 17 miles to west of Turkey Point, were simulated to be approximately 36ft, which slightl y underestimates observed water levels (approximately 37.5 ft NGVD29). The ECFAS2 model si mulates a water level of 39 feet at this location, after 350 days of simulation. Simulated water levels at W ASA-South, located to the n011h of Turkey Point, are approximately 35 ft NGVD 29; this well, however, was omitted from the ECFAS2 modeling analysis due to anomalous water levels (Golder Associates, 2008).

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Tablc3 P arameter c 1anges resu I tmg

. f rom ca J'b 1 ration o f t I1c Ad apted Flone

'I an mo d e.I ECFAS2 model FPL Floridan Model Hydrologic Model Aquifer (original) (recalibrated)

Unit Layers Parameter magnitude magnitude 0.0006 0.001 Kz (fUd)

ICU 2 0.000075 0.001 Kh (fUd) 0.000075 0.001 5.2 100 Kz (fUd) 9 15 72.5 225 0.33 225 UFA 3,4 52 100 Kh (ft/d) 90 150 725 330 3.33 330 Ss 5.25E-07 8.00E-07 0.004 0.003 0.000002 0.08 Kz (fUd) 0.4 0.003 MCU 5,6 0.002 0.08 0.02 0.08 Kh (fUd) 0.00001 0.4 0.03 Kz (fUd) 5.2 30 450 900 MFA 7,8 300 600 Kh (fUd) 180 1200 52 600 0.0015 0.01 MC2 9,10,11 Kz (ft/d) 0.0002 0.02 3.3 Predictive Simulations Once calibration of the regional Floridan model was confirmed, equilibrium flow conditions were established by running the model, holding all flow boundaries (e.g. specified heads) constant until changes in the simulated flow field in the Florida n Aquifer System were negligible. No pumping was simulated in this equi librium model. The resulting equilibrated state formed the initial conditions for ensuing predictive simulations. Equilibrated regional water 7

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levels, especially near Turkey Point, were generally lower than observed water levels; this is due to the exclusion of salt transport and the associated density-dependent flow. However, given that purpose of th is model is to provide estimates of relative changes in water level , the low simulated water levels were deemed irrelevant. Since the focus of the salinity reduction well evaluation is regional drawdown, the original 2400-ft grid spacing was employed for predictive simulations.

According the SFWMD BOR, predictive evaluations made with the calibrated model must be conducted using monthly stress periods that simulate average annual groundwater withdrawals subject to rainfall that alternates between average and 1-in-1 0 year draught conditions (3 months of average cond itions, followed by 12 months of drought conditions, followed by 6 months of average conditions). As such, the predictive models were conducted using 21 monthly stress periods .. Due to the specified head boundary in the topmost layer of the model, climatic stressess were not varied between average and drought conditions. Moreover, it is not anticipated that variation in rainfall would impact the Floridan aquifer over the 21-month timeframe of the simulation.

Additionally, the BOR stipulates that the 1-ft drawdown contour associated with the proposed pumping be simulated and the impacts to existing legal users' wells within that contour be evaluated. The process by which this was accomplished is described below.

3.3.1 Proposed Salinity Reduction Well Operation There are six proposed salinity reduction wells. At any one time, five of these well s will collectively pump 14 MOD of low salinity water from the Upper Floridan aquifer. The six wells will be spaced approximately 1900 ft apart, along the northernmost canal of the Cooling Canal System and along the Interceptor Ditch (Figure 7). In the model , the 14 MGD of pumping is distributed evenly amongst the five active wells and is assumed to be a constant rate of pumping over the course of the 25-year simulation. Two alternative pumping scenarios are considered in this modeling analysis and differ in the aJJocation of pumping to wells F-2 and F-6. The base scenario simulates pumping at wells F-1 through F-5 (no pumping at F-6); the alternative scenario simulates pumping at wells F-1 and F-3 through F-6 (no pumping at F-2).

The salinity reduction wells were simulated, starting from an equilibrium flow field. Aside from these salinity reduction wells, no pumping was simulated in this model such that the permitted users w ithin the 1-ft drawdown contour could be delineated. At the conclusion of the 21-month simu lation, the simulated drawdowns in the regional model are those attributable only to the five proposed salinity reduction wells. Figure 8a illustrates these regional drawdowns associated with the base pumping scenario. In this base simulation, the drawdowns at a distance from the site are affected by variations in hydraulic conductivity; this is evident upon inspection of the 1-ft drawdown contour, wh ich generally has an oblong shape, whose major axis is oriented north-to-south . Nearer to the site, the drawdown contours radiate outward from the wells in a more uniform manner, where the maximum drawdown is approximately 15.1 ft, near well F-3. In the alternative scenario, the maximum drawdown is approximately 14.4 ft, near well F-5.

As previously mentioned, the SFWMD BOR dictates tbat drawdown at permitted users' wells encircled by the 1-ft drawdown contour be determined. As illustrated in Figure 8a, the following permitted users fall within the 1-ft drawdown contour:

8 TETRA TECH

  • Card Sound Golf Club,
  • Ocean Reef Club,
  • the F loridan Keys Aqueduct Authority (FKAA),
  • Miami-Dade Water and Sewage Department South Miami Heights Wellfield, and
  • FPL Unit 5 Wells.

A second 21-month simulation was conducted wherein pumping by permitted users and the proposed salinity reduction wells was simulated. Predicted drawdowns attributable solely to permitted Floridan pumping were determined by comparing drawdowns from this simulation (Figure 8b) to those attributable to the proposed salinity reduction wells alone (Figure Sa).

These permitted well-based drawdowns are illustrated in Figure 9 for the base pumping scenario. Pred icted drawdowns at Floridan wells of these existing legal users due to the proposed operation of the salinity reduction wells are presented in Table 4. These drawdowns are calculated at the center of the model grid cells in which the respective wells are simulated. In addition to drawdowns attributable to the proposed wells for the base pumping allocation scenario, cumu lative drawdowns at nearby wells due to both pumping at permitted and proposed welJs are provided in Table 4. Withdrawals by nearby users were simulated at their respective permitted rates.

Table 4. Predicted drawdown at nearby users for the proposed Salinity Reduction Wells due to the base pumpmg scenano.

Distance Base Scenario Permitted Base Scenario Location from Drawdown at Facility Withdrawal Cumulative (L,R,C) well F-2 3,15, and 21 (MGD) Drawdown (ft)

(miles) Months (ft)

Card Sound Golf (3-Club (WUP 44- 0.58 8.8 1.85/2.20/2.21 9.83/11.47/1 1.54 4, 173,93) 00001)

Ocean Reef Club (3-1.42 8.8 1.85/2.20/2.21 9.83/1 1.47/11 .54 (WUP 44-00002) 4,173,93)

FKAA (3-9.70 10.3 1.76/2.15/2. 16 416.06/17.78/1 7.85 (WUP 13-00005) 4, 155,61)

South Miami Hts (3-4, 133-23.3 10.3 1.83/2.25/2.26 46.71/48.72/48.80 (WUP 13-00017) 135,79)

FPL Unit 5 Well (3-14.3 < 1.0 11.44/11 .85/11 .86 34.11/35.92/35.99 (PW-1) 4, 156,85)

A second evaluation was conducted in which the a lternative pumping allocation (wells F-1 and F-3 through F-6) for the salinity reductions wells was simulated. The resulting simulated drawdowns at legal users within the 1-ft drawdown contour are provided in Table 5; cumu lative drawdowns are also tabulated. Inspection of the drawdowns in Table 5 reveals that they are not significantly different from those produced by the base pumping allocation.

The cumulative drawdown due to permitted pumping, as illustrated in Figure 9, are not significantly different than those produced by the combination of proposed and permitted withdrawals (Figure 8b ). This suggests that the proposed pumping of Floridan water by the salinity reduction wells will not s ignificantly exacerbate drawdowns in the Upper Floridan aquifer beyond those induced by existing permitted pumping.

9 TETRA TECH

Table 5. Predicted drawdown at neuby users for the proposed Salinity Reduction Wells due to the a Iternatlve

. pumpmg

. scenano.

Alternative A lternative Distance Scenario Location Scenario Facility from well Drawdown at (L,R,C) Cumulative F-2 (miles) 3,15, and 21 Drawdown (ft)

Months (ft)

Card Sound Golf Club (3-4, 173,93) 8.8 1.86/2.21/2.22 9.84/11.48/11 .56 (WUP 44-00001)

Ocean Reef Club (3-4, 173,93) 8.8 1.86/2.21/2. 22 9.84/11.48/11.56 (WUP 44-00002)

FKAA (3-4, 155,61) 10.3 1.78/2.17/2.18 16.08/17.80/17.87 (WUP 13-00005)

South Miami Hts (3-4, 133-10.3 1.81 /2.22/2.24 46.68/48.69/48.78 (WUP 13-00017) 135,79)

FPL Unit 5 Well (PW-1) (3-4,156,85) < 1.0 9.92/10.33/10.35 32.59/34.40/34.47 4 Conclusions The evaluation of drawdown due to pumping at the proposed salinity reduction wel ls is based on the ECFAS2 model developed for the SFWMD. This model was subsequently adapted to site-specific conditions and re-calibrated to two APTs performed at Turkey Point. The resulting regional calibrated groundwater flow model provides assessment of drawdown at nearby existing Floridan water users.

In a regional sense, the proposed pumping of 14 MGD is projected to result in a maximum Upper Floridan Aquifer drawdown ranging between 14.4 ft (alternative scenario) and 15.1 ft (base scenario) at the Turkey Point site; simulated drawdowns at a distance from Turkey Point are not significantly different between the two pumping scenarios. The extent of drawdown, as defined by the 1-ft drawdown contour encompasses four existing legal users. Overall, the impacts to off-site permitted wells are minor. The maximum drawdown due to the proposed salinity reduction wells experienced by the nearest (non-FPL) users is 2.26 ft and occurs at the South Miami Heights wellfield, located approximately 10.3 miles away. Th is drawdown comprises approximately 4.6% of the cumulative drawdown simulated at this s ite. The drawdown contribution by the proposed salinity reduction wells is a conservative estimate (greater than would actually be experienced), since the drawdown in the wellbore at each nearby user due to localized pumping is undersimulated by the coarse-gridded regional model.

In addition to a demonstration of minimal drawdown induced at wells of permitted users within the 1-ft drawdown contour, the BOR also stipulates that the proposed pumping not impact the saltwater interface, as defined by the 250 mg/L isochlor. As the quality of Upper Floridan Aquifer water in this area already exceeds such a concentration, and no saltwater interface exists, this stipulation does not apply to the proposed project. Moreover, the operation of the salinity reduction well is not expected impact Upper F loridan water quality in a regional sense. Local changes in water quality are expected to be minor, as demonstrated by other Upper Floridan water users in the region (SFWMD, 20 12).

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5 References Anderson, M.P., and Woessner, W.W., 1992, Appl ied Groundwater Modeling- Simulation of Flow and Advective Transport: San Diego, Ca, Academ ic Press, 381 p.

Dames and Moore, 1975. Floridan Aquifer Water Supply Investigation, Turkey Po int Area, Florida.

Golder Associates, 2008. East Coast Floridan Aquifer System Model, Phase 2, Southeastern Florida, final Model Documentation Report, October 2008, 259pp.

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- User guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92, 121 p.

HydroGeoLogic, 2006. Development of a Density-Dependent Saltwater Intrusion Model for the Lower East Coast Project Area, April 2006. 166 pp JLA Geosciences, 2006. Well Completion Report for Floridan Aquifer Wells PW-1 , PW-3, and PW -4. FPL Turkey Point Expansion Project (Unit 5) Homestead, Florida.

Langevin, C.D., D.T. Thorne, Jr, A.M . Dausman, M.C. Sukop, and W. Guo, 2008, SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport: USGS Techniques and Methods Book 6, Chapter A22, 39 p.

South Florida Water Management District (SFWMD), 2012, Overview and Current Use of the Floridan Aquifer System in the Lower East Coast, Public Workshop, Pompano Beach, Florida, Apri118, 2012.

Zheng, C., and P. Wang, 1999, MT3DMS, A modular three-dimensional multi-species transport model for simulation of advection, dispersion and chemical reactions of contaminants in groundwater systems; documentation and user's guide, U.S. Army Engineer Research and Development Center Contract Report SERDP-99-1, Vicksburg, MS, 202 p 11 TETRA TECH

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P;\FPL\Salinity Reduction\GIS\F1g6_Coodl6.mxd

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-- -- 5 20 Legend Calibrated Conductivity Original Conductivity - - Cooling Canals D 2.0E-03 ft/d TITLE: Distribution of Vertical Hydraulic Conductivity in t he Middle Confining Unit a) Original Model, Prior to Additional Calibration and b) After Additional Calibration CJ 2.0E-06 ft/d 3.0E-03 ft/d LOCATION:

D 2.0E-03 ft/d D 4.0E-03 ft/d Turkey Point, Florida D 4.0E-03 ft/d D

5.0E-03 ft/d 1.5E-02 ft/d D 1.5E-02 ft/d 8.0E-02 ft/d 4.0E-01 ft/d

(-n:] TETRA TECH CHEC ORAFTE PROJ OATE PFA scs 117-2826019 0311012014 FIGURE:

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P:IFPL\Salini!y Reductlon\GIS\NewWells_SCA.mxd t

F-1J 1

Legend TITLE: Location of Proposed Salinity Reduction Wells

  • Proposed Wells Screened in the U er Floridan A uifer LOCATION:
  • Existing Unit 5 Wells Turkey Point, Florida

['A:) TETRA TECH CHECKE DRAFTED PROJ DATE PFA JlR 117-2826019 03/31/2014 FIGURE:

7

P.\FPL\SW'lnity Recmtion'1GIS\Redonat_OON_21Mo_SCA.mxd 0

5 10 Sea~ In Mles 0

- 5 10 Scat.lnMies TITlE:

a) Predicted UFA Drawdown Due to Proposed Wellfield, and Legend b) Cumulative UFA Drawdown Due to Permitted and Proposed Wellfields

  • Existing User Wells LOCATION:

Turkey Point, Florida Drawdown Contours (1 ft)

[-n::)

CHECK PFA FIGURE:

ORAFTE JLR TETRA TECH PROJ 117-2826019 8 DATE 11/5/2014

P:IFPL\Salinily Reduction'I31S\Permilled_Q_ DDN_ 21 Mo_ SCAmxd Club (WUP 44-00002) 0

-- 4

-- 8 16 Legend TITLE: Simulated Equilibrium Drawdown in Upper Floridan Aquifer

- - Drawdown Conto urs due to Permitted Pumping LOCATION;

- - Coo ling Canals Turkey Point, Florida CHECKE PFA FIGURE;

  • Existing User Wells

["jl;:) TETRA TECH DRAF TED JLR PROJ 117-2826019 9 DAT E W S/2014

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