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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
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)
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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.

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.

2 METHODOLOGY 2.1 Geneml 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

Conceptua l model development

Code se l ection Model design

Calibration I verification

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.

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.

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.

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.

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 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 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.

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.

3.2 Adapted 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.

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

simulates groundwater flow,

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

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.

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 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.

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 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 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months 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.

In general, hydraulic conductivitie s were increa sed from their orig in al values during calibration.

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.

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

-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

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.

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.

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,

Ocean Reef Club,

the F l o ridan Key s Aqueduct Authorit y (FKAA),

Miami-Dade Water a nd Sewage Departm e nt South Miami H eig h ts W e llfield , 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.

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.

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)

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

.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.

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.

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

/11.5 6 (WUP 44-00001)

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 (3-4, 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 , 133-10.3 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:

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

'------j FIGURE: DRAFTED SCS PROJ 1 17-2826019 1 DATE 031 1 0120 14

---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 £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

---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

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)'

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)'

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.:-

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

_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

_SCA.mxd Legend T ITLE:

Proposed We ll s LOCATION:

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

Existing User Wells Drawdown Contours (1 ft) 0 5 10 ----

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

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

( *at:) TETRA TECH F rom: To: D ate:

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.

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.

2 METHODOLOGY 2.1 Geneml 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

Conceptua l model development

Code se l ection Model design

Calibration I verification

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.