ML18213A432

Attachment M: Expert Reports from Lee Hefty

ML18213A432
Person / Time
Site:	Turkey Point
Issue date:	07/18/2018
From:	Hefty L Miami-Dade County, FL, Dept of Environmental Resources Management
To:	Atomic Safety and Licensing Board Panel
SECY RAS
Shared Package
ML18213A417	List: ML18213A418 ML18213A419 ML18213A420 ML18213A421 ML18213A422 ML18213A423 ML18213A424 ML18213A425 ML18213A426 ML18213A427 ML18213A428 ML18213A429 ML18213A430 ML18213A432 ML18213A433 ML18213A434 ML18213A435 ML18213A436
References
License Renewal, RAS 54382, 50-250-SLR, 50-251-SLR
Download: ML18213A432 (61)

Text

Attachment M Department of Regulatory and Economic Resources Environmental Resources Management MIAMI-DADE 701 NW 1st Court, 4th Floor COUNTY Miami, Florida 33136-3912 T 305-372-6754 F 305-372-6759 Carlos A. Gimenez, Mayor miamidade.gov July 18, 2018 Lea Crandall, Clerk of the Department CERTIFIED MAIL NO 7001 2510 0001 1765 4022 Office of General Counsel RETURN RECEIPT REQUESTED Florida Department of Environmental Protection 3900 Commonwealth Boulevard Tallahassee. Florida 32399-3000 Timothy Rach, Program Administrator CERTIFIED MAIL NO 7001 2510 0001 1765 4176 Submerged Lands and Environmental Resources RETURN RECEIPT REQUESTED Coordination Program Florida Department of Environmental Protection Bob Martinez Center 2600 Blair Stone F :oad MS 2500 Tallahassee, Florida 32399-2400 Re: Request for an Extension of Time in accordance with Section 120.57, Florida Statutes regarding Florida Power & Light (FPL) Permit No. 0193232-182, Everglades Mitigation Bank Phase II Modification and Credit Release dated June 28, 2018, for FPL facilities located in southern Miami-Dade County approximately 6 miles southeast of Florida City and Homestead, Between US Highway 1 and Card Sound Road, in Sections 5-8, 18, 19 and 28-33 in Township 58 Range 40 East; Sections 20-22, 25-29 and 32 36 in Township 58 South, Range 39 East; Sections 1 and 2 in Township 59 South, Range 39 East; and Section 6 in township 59 South, Range 40 East, Unincorporated Miami-Dade County, Florida.

Dear Ms. Crandall and Mr. Rach:

On June 28, 2018, Miami-Dade County Division of Environmental Resources Management (DERM) received via email the Florida Department of Environmental Protection (FDEP) letter issued June 28, 2018 regarding Florida Power & Light (FPL) Permit No. 0193232-182, Everglades Mitigation Bank Phase II Modification and Credit Release.

The subject permit modification "updates specific conditions based on recent data received to clarify the amount of freshwater Everglades Mitigation Bank Phase II (EMB 2) receives south of the L-31-E levee, allows for incremental vegetative success credit releases, and releases 98.55 freshwater herbaceous credits."

Furthermore, FDEP has required the permittee to lower the control elevation of the Everglades Mitigation Bank culvert weirs from 2,2 feet to 1 .8 feet NGVD within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of issuance "to assure that the area south of L E is receiving appropriate amounts of freshwater flow..."

The purpose of this letter is to respectfully request additional information and clarification from FDEP on this action, and to hereby request a sixty (60) day extension of time to September 17, 2018 for DERM to further review and fully evaluate FDEP's action in this matter in order to contemplate action regarding a petition for an administrative hearing in accordance with Section 120.57, Florida Statutes.

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Page 2 of 5 Over the past several years, DERM has been working with FPL on concerns over water quality impacts associated with the FPL Turkey Point Cooling Canal System (CCS). On October 7, 2015, FPL entered into a Consent Agreement with DERM to address these water quality impacts. The Consent Agreement identified various remedial actions and hydrologic improvement projects that FPL was required to undertake to address water quality impacts, including one such requirement that FPL increase the Everglades Mitigation Bank culvert weirs elevation to no lower than 0.2 feet below the 2.4 foot NGVD trigger of the S-20 Structure. This condition was included in the Consent Agreement because of concerns associated with the impacts of the hyper saline plume emanating from the CCS on water resources in the area. The FPL Turkey Point CCS, as well as FPL's Everglades Mitigation Bank are located in the extreme southeast region of the county in an area that is experiencing significant westward migration of the salt intrusion front at the base of the Biscayne aquifer, and where historically fresh surface water canals have recently been documented with higher conductivity and chloride levels uncharacteristic of fresh water bodies. Miami-Dade County is concerned that the subject modification, as issued, establishes operating criteria for the EMB2 culvert weir elevations and target water deliveries that: may result in adverse impacts to water resources upstream of this area; and that are not sustainable over the long term, particularly as it relates to existing inland migration of the salt intrusion front in this area, which is expected to be further exacerbated by sea level rise.

The following describes some of DERM's concerns regarding the aforementioned subject permit modification:

1. Upstream Water Levels and Salt Intrusion

a. The DEP-mandated control elevation of 1 .8 foot NGVD is 0.6 feet below the current drainage trigger elevation at the adjacent S-20 water control structure. DERM is concerned that setting the control elevation at 1 .8 feet NGVD is not sustainable from a water management perspective. The stage in the L-31 E canal is dependent on the setting of the adjustable weirs in these 40 culverts. The decision to modify the permit and set the culverts to 1 .8 feet will cause the water levels in the L-31 E canal to drain to this elevation. In addition, the wetlands in the Model Lands Basin will be drained by the L-31 E canal whenever the stage in the upstream wetlands exceeds the DEP mandated 1 .8 feet NGVD control elevation of the canal. This drainage has and will continue to undermine the ecological functioning of the wetlands upstream of the L-31E, including wetlands that are part of the mitigation bank.

b. The EMB 2 is located east of the salt intrusion line, as delineated by the 1000 ppm isochlor at the base of the Biscayne Aquifer. The salt front migrates westward (inland) in this area when water levels upstream of the L-31 E are insufficient to prevent this salt intrusion, therefore, water management in the bank and the surrounding basin is critical for preventing the landward migration of the salt front, towards potable water wellfields in the Homestead area, including the Florida Keys Aqueduct Authority wellfield that provides drinking water for the Florida Keys and Miami-Dade County's Newton wellfields. Attachment 1 demonstrates how low the surface and groundwater levels can fall in this basin which is drained by the EMB 2 culverts. It is notable that during some drought years, the groundwater levels in this basin can fall below sea level in the area upstream of the L-31E.

c. The most recent USGS study indicates that the current average rate of landward migration of the saltwater interface in the groundwater is at 140 meters per year and that the salt front now extends beyond monitoring well cluster TPGW-7 of the FPL Turkey Point Uprate Project. This study supports the conclusion that the groundwater salt front in this basin has been advancing upgradient towards the aforementioned public wellfields and private drinking water wells as a result of unsustainable water management practices; this includes the removal of more water from this basin than it receives via rainfall. A copy of the aforementioned USGS study is provided as Attachment 2. It should be noted that the saltwater front is currently located more than 6.5 miles inland at the northern boundary

Page 3 of 5 of the basin and more than 10.6 miles at the SW boundary of the basin at the 1000 ppm isochlor line. An illustration of this saltwater front is provided in Attachment 3.

d. The extent to which the L-31 E Canal (which historically was a freshwater canal) can be protected from saltwater contamination is dependent on the stage of the canal. Attachment 4 depicts the recent extent of chloride contamination of this canal. It should be noted that the L-31 E canal is connected to upstream secondary canals including the Model Lands South canal, therefore chloride impacts observed in the L-31 can now become a potential surface water pathway for further chloride contamination of the secondary canal system as well. Attachment 5 depicts the locations in the secondary canal where elevated conductivities have recently been detected. Attachment 6 includes a meeting presentation with information on the hydrology of the Model Lands basin and how the basin is impacted by FPL's water management operations. Attachment 7 summarizes salinity increases in the L-31 E over the Uprate Project monitoring period of record, demonstrating the high degree of salinization that has occurred in these surface waters. The water quality of the L-31 E was initially freshwater and salinities during the period of record have increased to over 29 PSU.

e. DERM has considered the cumulative impact of water losses from the Model Lands Basin with the permit-mandated minimum annual flows through the culverts, given other water losses from this basin and nearby areas. These include the losses associated with operation of the Interceptor Ditch (ID) pumps and the groundwater recovery well system (which is now operational). As an example, the flows mandated in this permit modification in combination with the recovery well system will result in more than 20,000 acre-feet of water lost from this area annually. This is the equivalent of more than one foot of surface water across the entire Model Lands wetlands and does not include other permitted water losses such as those associated with replacement of water from operation of the ID pumping into the cooling canals pursuant to the authority granted under the Fifth Supplemental Agreement with the South Florida Water Management District. It is also not clear if FDEP has considered the increased pumping losses that are expected from the ID operations since the stage triggers for the ID pumping have not been modified and since lower water levels in the L-31 E Canal in relation to cooling canal stage is the condition that triggers the operation of the ID pumps.

2. Comprehensive Everglades Restoration Plan (CERP) Consistency

a. A control elevation of 1.8 feet NGVD is not sustainable or consistent with Everglades restoration in this area including the restoration envisioned under the C-1 1 1 Spreader Canal Phase One CERP project. In order to restore more natural hydroperiods and stages to the wetlands in the Model Lands basin, this CERP project calls for a control elevation much higher than the 1.8 foot elevation mandated in the DEP permit modification. Please refer to the C-1 1 1 Spreader Western Project implementation report for further information relating to this CERP project. Under this CERP project, the adjacent S-20 water control structure will be operated at a 2.9 foot NGVD open trigger when the approved trigger changes are fully implemented, and the structure will close at an elevation not lower than 2.4 feet NGVD. A series of hydrographs depicting the aforementioned concept is provided as Attachment 8. In the absence of new water sources, this attachment helps to illustrate the concern that water levels in the Model Lands wetlands will not likely be able to reach the 2.9-foot CERP open trigger stage during typical (or even wet) water years based upon the DEP-mandated culvert control elevation. Therefore, setting the culvert weirs at the 1 .8 foot control elevation will drain the water above this elevation through these culverts and, as a result, will prevent most or all of the hydroperiod and stage benefits to the Model Lands that were envisioned with the CERP S-20 operations change.

In order to preserve the ability of the CERP S-20 operations change to provide stage and hydroperiod benefits (as well as salt intrusion prevention benefits), the water levels in the L-31E canal should be held to canal stages of 2.4 feet or higher as approved by CERP. This CERP restoration strategy to operate the S-20 structure at a 2.9-ft NGVD open trigger has been authorized by FDEP through

Page 4 of 5 issuance of FDEP permit number 0293559-011; however, FDEP's recent permit modification to order lowering of the FPL culvert gate elevations is inconsistent with this CERP restoration strategy and negates it. FDEP's action appears inconsistent with the CERP S-20 operations change, and also appears inconsistent with the Army Corps permit for construction of the FPL Everglades Mitigation Bank (SAJ-1 995-1 55(IP-TKW)), which states "This permit does not authorize interference with any existing or proposed Federal projects."

3. Miami-Dade-owned and other Conservation Lands

a. Public conservation lands, a significant portion of which are owned by Miami-Dade County's Environmentally Endangered Lands Program, are located upstream of the culverts in the Model Lands Basin and are affected by competing freshwater needs. State and Federal agencies have recognized the need to restore more natural hydroperiods in this area as per the numerous CERP projects designed to restore wetlands in this specific area. The reset of the culvert weirs back to 1 .8 feet NGVD as per the permit modification will serve to further drain and adversely impact these Miami-Dade County-owned conservation lands. Additionally, hydrologic impacts including salt intrusion and groundwater and surface water contamination have been documented on these lands.

A map depicting the results of recent sampling that reveal water quality impacts to surface waters within these publically-owned wetlands is provided as Attachment 9. Evidence based on recent sampling indicate that saline water has entered the secondary canal from the L-31 E Canal. An illustration of the extent of the saline groundwater plume from the cooling canal system on these Miami-Dade County-owned conservation lands, based on tritium tracer contours, is provided as Attachment 10.

4. Methodology for Release of EMB Wetland Mitigation Credits

a. As a regulatory agency that accepts State permitted mitigation banking credits, DERM is concerned about the manner in which the determination that a credit release was appropriate and how the calculations reflected in the credit release schedule were completed. The modification of the permit and credit release appears inconsistent with the findings of the FDEP inspection report dated March 21, 2018. Specifically, It appears that EMB2 was requesting a partial release of 98.55 credits for meeting herbaceous wetland vegetation interim success criteria; however, the FDEP inspection report documents that the success criteria is not being met. Furthermore, changes in the permit language appear to correlate the lowering of the L-31E culverts with the success of vegetation planted in graded and restored areas. However, it is not clear how the success of vegetation in areas upstream of the L-31E culverts is related to the lowering of the control elevation for the weirs.

b. In addition, specific Condition 20 in the Modification refers to the "Credit release schedule on the next page..." - Yet, the attached credit release schedule has been modified to actually add credits and the "Time Lag & Risk" has been modified from 33.08 to -129.82. It is unclear whether there was an error in the calculation or if there was an actual increase in the allowable credits based on the subject permit modification.

c. The modification document states " This modification releases a total of 98. 55 freshwater herbaceous credits to the EMB2. The credits are being released in accordance with Specific Condition 20 and the credit release schedule of Environmental Resources Permit (ERP) #0193232-055." However, the credit release schedule being referenced is actually from the 2013 permit modification and is different than the one that is attached to the current modification. Specifically, the credit release schedule referenced does not indicate that the credits can be released incrementally.

Page 5 of 5

5. Miami-Dade County DERM Consent Agreement with FPL

a. The subject modification conflicts with the October 7, 2015 DERM Consent Agreement in that resolution of paragraph 17.c.i. relating to the control elevation of the culverts has not been achieved.

DERM and FPL have not concluded discussions on this matter and any submittals to DERM by FPL to change the culvert settings have not been finalized by both parties. Furthermore, the Consent Agreement requires FPL to take into account its efforts to improve CCS water quality and the potential and actual impacts of such actions on water resources outside the CCS, to not cause or contribute to the exacerbation of alleged violations of County water quality standards or criteria or future violations of County water quality standards or criteria in the groundwater or surface waters outside the CCS.

In order to adequately evaluate DEP's action, DERM is respectfully requesting the following records and information:

a) All information/data and analysis that FDEP has relied upon for the modification of the permit and for its determination that these permit modifications "are not expected to result in any adverse environmental impacts or water quality degradation, and will not be contrary to public interest" as stated in FDEP's June 28, 2018 letter approving the permit modifications.

b) All data that FDEP has received from the mitigation bank including, but not limited to, all stage and water quality data from the four monitored culverts, as well as all stage data from all monitoring locations downstream of the L-31 E canal.

c) Finally, DERM requests a copy of any notifications the permittee has provided to FDEP pursuant to the requirements of General Condition 10 of the above referenced permit.

Please contact me at 305-372-6754 if you have any questions regarding this matter.

Sincerely, cee N. Hefty, Director Division of Environmental Resources Management ec: John Truitt, Deputy Secretary Regulatory Programs, Florida Department of Environmental Protection Ernest Marks, Executive Director South Florida Water Management District Michael W. Sole, Vice President, Environmental Services, NextEra Energy Inc.

Matthew Raffenberg, Senior Director - Environmental Services, FPL/NextEra Abbie Schwaderer-Raurell, Assistant County Attorney Miami-Dade County Rashid Istambouli, RER Sr. Division Chief Division of Environmental Resources Management Craig Grossenbacher, RER Division Chief Division of Environmental Resources Management Lisa Spadafina, RER Division Chief, Division of Environmental Resources Management Wilbur Mayorga, RER Division Chief. Division of Environmental Resources Management Donna Gordon, RER Section Chief, Division of Environmental Resources Management

ATTACHMENTS SIN 3 l/\l H 0V11V

Stage (ft NGVD) 0 0.5 1 1.5 2 2.5 3 3.5 1/1/2000 7/1/2000 1/1/2001 7/1/2001 1/1/2002 7/1/2002 1/1/2003 7/1/2003 1/1/2004 7/1/2004 1/1/2005 7/1/2005 1/1/2006 7/1/2006 1/1/2007 7/1/2007 S-20 Stage (ft NGVD) 1/1/2008 L-31E Water Levels 7/1/2008 1/1/2009 7/1/2009 1/1/2010 7/1/2010 1/1/2000 - 6/30/2018 Model Lands Basin 1/1/2011 7/1/2011 1/1/2012 7/1/2012 1/1/2013 Sea Level (0.67 ft NGVD) 7/1/2013 1/1/2014 7/1/2014 1/1/2015 7/1/2015 1/1/2016 7/1/2016 1/1/2017 7/1/2017 1/1/2018

Prepared in cooperation with Miami-Dade County Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer in the Model Land Area of Miami-Dade County, Florida, 2016 EXPLANATION Naranja Well field Park Approximate inland extent of saltwater in 2011 (Prinos and others, 2014)

Approximation Dashed where data are insufficient G-1180 Approximate inland extent of saltwater in 2016 Homestead 22 Approximation Airforce  !

Redavo Dashed where data are insufficient Base Leisure G-3698 ! Monitoring well name and chloride concentration, in milligrams per liter City 2,830 Harris Park Wittkop Park G-3698 2,830  ! Biscayne Bay Newton G-3976 G-3966S TPGW-12L Florida City 36 5,610 G-3900  !  ! 27,100

!  ! G-3699 TPGW-6L 31 SWIM well  ! 10,700 7,570  !

!  !

130 G-3855 TPGW-10L Florida Keys FKS 9 7,960  ! 26,400 Aqueduct 48  !

Authority ACI-MW-05 ! Sec34-MW-02-FS

! TPGW-1L 47.4  !  !

29,100 ACI-MW-04 TPGW-7L G-1264 48.5  ! 2,750  ! 8,300 Everglades ACI-MW-03  !

Labor Camp TPGW-5L

! 17.8 !  ! 12,300 ACI-MW-09 ACI-MW-15 30.8 2,480 G-3166

!  !  !

! G-3946D Model 150 TPGW-8L 46.2 5,780 Land TPGW-13L ACI-MW-16 36,800

! 36.9 Area TPGW-11L 25,300 !

FKS 8  !

10,050 TPGW-2L 31,200 Cooling TPGW-9L  ! canal FKS 5 system 31 25.2 FKS 4

!  !  !

! G-3342 3,150 TPGW-4L

!

FKS 7 2,390  ! 15,200 98 C-110 Canal FKS 6

! 51

!

G-3167 TPGW-14L 65  ! 27,800 TPGW-3L FKS 3 28,500 !

7,375 Card Sound

!

FKS 2 G-1603 FKS 1 643  ! 57  ! 763 FLORIDA Little Card Sound N

EA OC Miami-Dade NT IC County 0 2 4 KILOMETERS AT Study area LA 0 2 4 MILES Barnes Sound Scientific Investigations Map 3380 U.S. Department of the Interior U.S. Geological Survey

Cover. Map showing the approximate extent of saltwater at the base of the Biscayne aquifer in the Model Land Area of Miami-Dade County, Florida, 2016. See https://doi.org/10.3133/sim3380 for map sheet.

Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer in the Model Land Area of Miami-Dade County, Florida, 2016 By Scott T. Prinos Prepared in cooperation with Miami-Dade County Scientific Investigations Map 3380 U.S. Department of the Interior U.S. Geological Survey

U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey William H. Werkheiser, Acting Director U.S. Geological Survey, Reston, Virginia: 2017 For more information on the USGSthe Federal source for science about the Earth, its natural and living resources, natural hazards, and the environmentvisit https://www.usgs.gov or call 1-888-ASK-USGS.

For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Prinos, S.T., 2017, Map of the approximate inland extent of saltwater at the base of the Biscayne aquifer in the Model Land Area of Miami-Dade County, Florida, 2016: U.S. Geological Survey Scientific Investigations Map 3380, 8-p. pamphlet, 1 sheet, https://doi.org/10.3133/sim3380.

ISSN 2329-132X (online)

iii Acknowledgments The authors would like to acknowledge the organizations that provided data for the study area:

EAS Engineering, Inc., Florida Keys Aqueduct Authority, Florida Power & Light Company, Miami-Dade County, and South Florida Water Management District. Without the data provided by these organizations, the map in this report could not have been created.

v Contents Acknowledgments ........................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction ....................................................................................................................................................1 Mapping the Approximate Inland Extent of the Saltwater Interface ....................................................2 Approximating the Rate of Movement of the Saltwater Interface ........................................................2 Monitoring Network Improvements ...........................................................................................................3 References Cited ...........................................................................................................................................4 Appendix 1. Estimation of Chloride Concentrations at Wells Where Conductivity Profiles Were Used for Monitoring..................................................................................................5 Sheet

[Available from https://doi.org/10.3133/sim3380]

1. Map of the approximate inland extent of saltwater at the base of the Biscayne aquifer in the Model Land Area of Miami-Dade County, Florida, 2016 Conversion Factors SI to Inch/Pound Multiply By To obtain Length meter (m) 3.281 foot (ft) kilometer (km) 0.6214 mile (mi)

Area square kilometer (km2) 247.1 acre 2

square kilometer (km ) 0.3861 square mile (mi2)

Volume liter (L) 0.2642 gallon (gal) liter (L) 61.02 cubic inch (in3)

Flow rate meter per year (m/yr) 3.281 foot per year (ft/yr)

Mass gram (g) 0.03527 ounce, avoirdupois (oz) kilogram (kg) 2.205 pound, avoirdupois (lb)

Electrical conductivity siemens per meter (S/m) 10,000 microsiemens per centimeter (S/cm)

vi Electrical conductivity in microsiemens per centimeter [S/cm] can be converted to electrical resistivity in ohm-meters [ohm m] as follows: = 10,000/.

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 x °C) + 32 Datum Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Supplemental Information Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25 °C).

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L).

Abbreviations bls below land surface GIS geographic information system TSEMIL time-series electromagnetic-induction log (dataset)

USGS U.S. Geological Survey

Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer in the Model Land Area of Miami-Dade County, Florida, 2016 By Scott T. Prinos Abstract kilometers (km2) of the mainland part of the Biscayne aquifer were intruded by saltwater (Prinos and others, 2014). Intrusion The inland extent of saltwater at the base of the of the Biscayne aquifer by saltwater is a concern because it Biscayne aquifer in the Model Land Area of Miami-Dade can render the water unpotable in affected parts of the aquifer.

County, Florida, was mapped in 2011. Since that time, The maximum concentration of chloride allowed in drinking the saltwater interface has continued to move inland. The water is 250 milligrams per liter (mg/L; U.S. Environmental interface is near several active well fields; therefore, an Protection Agency, 2014), whereas saltwater-intruded parts of updated approximation of the inland extent of saltwater and the aquifer commonly have water with chloride concentrations an improved understanding of the rate of movement of the of 1,000 mg/L or greater.

saltwater interface are necessary. A geographic information The inland extent of saltwater at the base of the Biscayne system was used to create a map using the data collected by aquifer was last mapped by Prinos and others (2014) in 2011.

the organizations that monitor water salinity in this area. An Since that time, saltwater has continued to intrude beneath average rate of saltwater interface movement of 140 meters the Model Land Area. This area is a relatively flat and poorly per year was estimated by dividing the distance between two drained wetland area in southeastern Miami-Dade County that monitoring wells (TPGW-7L and Sec34-MW-02-FS) by the is bordered on the east and south sides by Biscayne Bay, Card travel time. The travel time was determined by estimating Sound, Little Card Sound, and Barnes Sound. A system of the dates of arrival of the saltwater interface at the wells and canals, water control structures, and levees regulate the flow computing the difference. This estimate assumes that the of surface water in this area. There is an extensive system of interface is traveling east to west between the two monitoring cooling canals in the eastern part of this area that has been wells. Although monitoring is spatially limited in this area hypersaline at times (Hughes and others, 2010).

and some of the wells are not ideally designed for salinity In the Model Land Area, the saltwater interface monitoring, the monitoring network in this area is improving is near several active well fields; therefore, an updated in spatial distribution and most of the new wells are well approximation of the inland extent of saltwater and an designed for salinity monitoring. The approximation of the improved understanding of the rate of movement of the inland extent of the saltwater interface and the estimated rate saltwater interface are necessary. The U.S. Geological Survey of movement of the interface are dependent on existing data. (USGS), in cooperation with Miami-Dade County, mapped the Improved estimates could be obtained by installing uniformly approximate inland extent of saltwater in the Model Land Area designed monitoring wells in systematic transects extending in 2016 and approximated the average rate of movement of the landward of the advancing saltwater interface. saltwater interface in this area based on data collected between 2007 and 2014. This study aligns directly with the strategic science direction for the Water discipline outlined in USGS Circular 1309 (U.S. Geological Survey, 2007) by quantifying, Introduction forecasting, and securing freshwater for Americas future.

The purpose of this report is to provide a map of the saltwater Seawater began intruding the Biscayne aquifer of Miami- interface (2016), an estimate of the rate of interface movement Dade County early in the 20th century because of a decline in given the dates of arrival at two wells, and a description of the the fresh groundwater level, estimated to have been 2.9 meters methodologies used to arrive at these results. The analyses and (m) below predrainage conditions near Miami (Prinos estimates are based on available data from existing monitoring and others, 2014). By 2011, approximately 1,200 square wells in the Model Land Area.

2 Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer, Miami-Dade County, Florida, 2016 Mapping the Approximate Inland basis, based on the available monitoring wells. The locations of the monitoring wells and the chloride concentration values Extent of the Saltwater Interface are shown on the map (sheet 1, available at https://doi.

org/10.3133/sim3380). The line depicting the approximate The approximate inland extent of saltwater in the inland extent of saltwater is dashed where the monitoring well Biscayne aquifer was determined by using (1) chloride distribution is insufficient to create a reasonably accurate and concentration and specific conductance of water samples precise approximation.

collected from monitoring wells, (2) water conductivity The TSEMIL-derived vertical profiles of bulk profiles collected in long open-interval wells, and (3) time- conductivity provide additional qualitative insights for series electromagnetic-induction log (TSEMIL) datasets mapping, such as detection of any influxes of conductive collected in polyvinyl-chloride-cased monitoring wells. This water that do not correspond to the open interval of the well information was provided by EAS Engineering, Inc., the and temporal changes in the depth of the top of the saltwater Florida Keys Aqueduct Authority, the Florida Power & Light interface. Where water conductivity profiles were used Company, the South Florida Water Management District for monitoring, chloride concentrations were estimated by (SFWMD), and the USGS. Almost all of the data provided using a relation based on a linear regression of the chloride by the SFWMD for this study area had been collected by the concentration and specific conductance as described in other four organizations, so they are mostly redundant. The appendix 1.

information was entered into a geographic information system The majority of the monitoring wells used for this (GIS) for analysis and mapping. Data used to make the map analysis have short open intervals (about 1.5 meters [m] or are available as a data release (Prinos, 2017). less), but 37 percent have open intervals of 8 to 40 m (Prinos, Sampling, analysis, and quality assurance procedures of 2017). The long open-interval wells are not ideal for salinity the organizations collecting salinity data in the study area vary. monitoring for the reasons summarized in Prinos (2013) and Procedures used by the Florida Power & Light Company for Prinos and Valderrama (2015), but they are the only wells sampling and quality assurance are described in the Turkey available at some locations.

Point Quality Assurance Project Plan (Florida Power & Light Company, 2011). These procedures are likely among the most stringent used by organizations collecting salinity data in the study area. This plan was drafted jointly by the Florida Approximating the Rate of Movement Department of Environmental Protection, the Florida Power of the Saltwater Interface

& Light Company, and the SFWMD and was approved by the SFWMD. Procedures for sampling by the USGS are The saltwater interface in the study area is advancing generally based on those described in the USGS field manual, at an estimated average rate of 140 meters per year (m/yr).

but procedures have been modified for expediency and This estimate is based on limited data because there are few efficacy of routine, long-term saltwater intrusion monitoring wells in this area where the date of arrival of the saltwater (U.S. Geological Survey, variously dated; Lee Massey, U.S. interface can be ascertained. Most wells were installed either Geological Survey, written commun., March 7, 2017). EAS after the saltwater interface had already passed the location Engineering, Inc., and the Florida Keys Aqueduct Authority or where the saltwater interface has not yet arrived. The base their sampling on the specifications of the Florida estimate is based on data from monitoring wells Sec34-Department of Environmental Protection (Florida Department MW-02-FS and TPGW-7L, monitored by EAS Engineering, of Environmental Protection, 2008). To ensure the quality of Inc., and the Florida Power & Light Company, respectively.

analyzed samples, the USGS laboratory participates in the Data from well TPGW-7L and selected conductance profiles Branch of Quality Systems Standard Reference Sample Semi- from well Sec34-MW-02-FS are available in Prinos (2017).

Annual Proficiency Testing Project. EAS Engineering, Inc., Well TPGW-7L is open to the aquifer from 24 to 26 m and the Florida Power & Light Company use laboratories that below land surface (bls), which is near the depth of the base are certified through the National Environmental Laboratory of the Biscayne aquifer at this location (Fish and Stewart, Accreditation Program. Participation in this accreditation 1991). The chloride concentration in water samples from program likely assures that sample analyses are accurate; well TPGW-7L increased from 180 to 825 mg/L between however, the USGS cannot completely verify this accuracy December 3, 2013, and March 11, 2014, and from 825 to without reviewing the results of the accreditation testing for 1,300 mg/L between March 11, 2014, and June 9, 2014.

each laboratory used. Water conductance profiles were collected from well Sec34-The approximate saltwater interface is represented by the MW-02-FS. The maximum conductance of the profiles was 1,000-mg/L isochlor at the base of the Biscayne aquifer. The found at a depth of about 25 m bls. Using equations 1 and word approximate is used because the spatial distribution 2 (appendix 1), conductance values measured at this depth of monitoring wells is generally insufficient to create a equate to chloride concentrations of about 190, 530, 930, and precise representation. The accuracy and precision of this 1,400 mg/L for November 12, 2007, January 15, 2008, April 4, approximation is best evaluated on a location-by-location 2008, and May 15, 2008, respectively.

Monitoring Network Improvements 3 The average rate of saltwater interface movement from the estimated location of the saltwater interface. The was estimated by dividing the distance between the wells 1,000-mg/L isochlor may not arrive at this well until 2023, (830 m) by the difference between the interpolated dates of if the rate of movement of the saltwater interface proceeds at arrival of chloride concentrations of 250 and 1,000 mg/L at the average rate estimated in this study. Better estimates of each well. The interpolated dates of arrival at well Sec34- the rates of movement are needed before 2023, particularly MW-02-FS were November 22, 2007, and April 8, 2008, because the rate of movement may not be constant.

for concentrations of 250 and 1,000 mg/L, respectively. Monitoring well FKS 5 is even farther from the approximated The interpolated dates of arrival at well TPGW-7L were location of the saltwater interface than well FKS 9. The rate December 13, 2013, and April 13, 2014, for concentrations of and direction of movement of the saltwater interface near well 250 and 1,000 mg/L, respectively. Given these dates and the FKS 5 are unknown. If the rate of movement were the same distance between these wells, the estimated rate of movement as that between wells Sec34-MW-02-FS and TPGW-7L, the of the front is 137 m/yr based on a chloride concentration of 1,000-mg/L isochlor may not reach this well for 26 years if 250 mg/L, and the estimated rate based on a concentration of the interface moves northward, or 17 years if the interface 1,000 mg/L is 138 m/yr. These estimates can be rounded to an moves westward. Water managers would most likely need to average estimate of 140 m/yr. This rate of movement was used have a better understanding of the location of the saltwater to help interpolate the location of the 1,000-mg/L isochlor in interface, its rate of movement, and direction of movement the Model Land Area. than currently provided near FKS 5.

This estimate assumes that the direction of front Differences in the design, placement, quality of chemical movement is parallel to a line passing through these two well analyses, and type of monitoring can add uncertainty to this locations, and that the rate of front movement is constant. analysis. The analysis of the rate of movement of the saltwater Use of this rate for interpolating the position of the saltwater interface between monitoring wells Sec34-MW-02-FS and interface elsewhere in the study area assumes that (1) effective TPGW-7L, for example, required a number of estimations, porosity is uniform throughout this area, (2) direction of including the relation between specific conductance and front movement is east to west, and (3) that the rate of front chloride, the relation between pumped water samples and movement is the same throughout this area. Additional in situ measurements of conductance, and the conversion of monitoring is needed to evaluate these assumptions (see conductance to specific conductance. These relations and Monitoring Network Improvements section of this report). conversions increase uncertainty.

Given the stated assumptions, the saltwater interface may Some monitoring wells, such as well Sec34-MW-move under the Newton well field by 2026. This estimate of 02-FS and many of the wells monitored by the Florida Keys future movement may be conservative because withdrawals Aqueduct Authority, are designed to monitor the depth of the from the well field may influence the rate and direction of top of the saltwater interface through the collection of water travel. conductivity profiles and water samples from multiple depths.

Because these wells have long open intervals, the sample results may be influenced by flow within the well bore during sampling or under ambient conditions (Prinos, 2013; Prinos Monitoring Network Improvements and Valderrama, 2015). Although several organizations base their sampling on the Standard Operating Procedures of the Within the map, the line depicting the approximation Florida Department of Environmental Protection, Prinos of the inland extent of the saltwater interface is dashed (2013) states that these procedures call for sampling of long near the Card Sound Road Canal and in the area around open-interval wells by pumping from near the top of the water the C-110 Canal because there were insufficient data for column or top of the open interval, which could result in an accurate delineation of the interface. These areas were samples that are not representative of maximum salinity in the previously mapped by using helicopter electromagnetic aquifer. Uncertainty is also increased because some analyses surveys (Fitterman and Prinos, 2012) and time-domain are performed in the field as opposed to in a laboratory that electromagnetic soundings (Fitterman and others, 2011). participates in a quality assurance testing program (see the Monitoring in these areas currently consists of only a few Mapping the Approximate Inland Extent of the Saltwater wells that are too far from the expected current location of the Interface section of this report).

interface to provide relevant information. Monitoring near the Estimates of the rate of movement of the interface could edge of the elongated extension of saltwater that had intruded be improved by placing monitoring wells along a transect, along the Card Sound Road Canal (Prinos and others, 2014) is spaced at distances that would allow timely detection of any almost nonexistent. variations in the rate of movement of the saltwater interface, Given the rate of movement of the saltwater interface and parallel to the direction of movement of the interface. If estimated in this investigation, the chloride concentrations four or five such transects were installed in the county, the of samples from some of the monitoring wells on the resulting data could be used to evaluate spatial differences in freshwater side of the interface may not exceed 1,000 mg/L for the rates of movement of the saltwater interface at locations many years. Monitoring well FKS 9, for example, is 0.86 km where the interface is encroaching. Collecting TSEMIL

4 Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer, Miami-Dade County, Florida, 2016 datasets in wells in each transect could provide information on Prinos, S.T., 2013, Saltwater intrusion in the surficial aquifer how the depth of the interface is changing. Using consistent system of the Big Cypress Basin, southwest Florida, monitoring methods at wells in each transect could reduce the and a proposed plan for improved salinity monitoring:

uncertainty in the estimated rate of movement. U.S. Geological Survey Open-File Report 2013-1088, 58 p., accessed January 5, 2017, at https://pubs.usgs.gov/

of/2013/1088/.

References Cited Prinos, S.T., 2017, Data pertaining to mapping the approximate inland extent of saltwater in the Biscayne Fish, J.E., and Stewart, Mark, 1991, Hydrogeology of the aquifer, in the Model Land Area of Miami-Dade County, surficial aquifer system, Dade County, Florida: U.S. Florida, 2016: U.S. Geological Survey data release, Geological Survey Water-Resources Investigations Report http://dx.doi.org/10.5066/F7R78CF8.

90-4108, 50 p., 11 sheets.

Prinos, S.T., and Valderrama, Robert, 2015, Changes in Fitterman, D.V., Deszcz-Pan, Maria, and Prinos, S.T., 2012, the saltwater interface corresponding to the installation Helicopter electromagnetic survey of the Model Land of a seepage barrier near Lake Okeechobee, Florida:

Area, southeastern Miami-Dade County, Florida: U.S. U.S. Geological Survey Open-File Report 2014-1256, Geological Survey Open-File Report 2012-1176, 77 p., 24 p., accessed January 5, 2017, at https://pubs.usgs.gov/

39 pls., accessed January 5, 2017, at https://pubs.usgs.gov/ of/2014/1256/.

of/2012/1176/.

Prinos, S.T., Wacker, M.A., Cunningham, K.J., and Fitterman, Fitterman, D.V., and Prinos, S.T., 2011, Results of time- D.V., 2014, Origins and delineation of saltwater intrusion domain electromagnetic soundings in Miami-Dade and in the Biscayne aquifer and changes in the distribution of southern Broward Counties, Florida: U.S. Geological saltwater in Miami-Dade County, Florida: U.S. Geological Survey Open File Report 2011-1299, 289 p., accessed Survey Scientific Investigations Report 2014-5025, 101 p.,

January 5, 2017, at https://pubs.usgs.gov/of/2011/1299/. accessed January 5, 2017, at http://dx.doi.org/10.3133/

Florida Department of Environmental Protection, sir20145025.

2008, Groundwater sampling: Florida Department of U.S. Environmental Protection Agency, 2014, Secondary Environmental Protection, Standard Operating Procedures, drinking water standards: Guidance for nuisance chemicals:

DEP-SOP-001/01 FS2200, 26 p., app., accessed U.S. Environmental Protection Agency Report 816-f February 10, 2017, at http://www.dep.state.fl.us/Water/sas/ 079, accessed January 26, 2011, at http://water.epa.gov/

sop/sops.htm. drink/contaminants/secondarystandards.cfm.

Florida Power & Light Company, 2011, Quality Assurance U.S. Geological Survey, variously dated, National field manual Project PlanTurkey Point Monitoring Project: Florida for the collection of water-quality data: U.S. Geological Power & Light Company, 170 p., 9 app., accessed Survey Techniques of Water-Resources Investigations, February 22, 2017, at https://www.sfwmd.gov/documents-book 9, chaps. A1-A9, available online at http://pubs.water.

by-tag/fpltpsurvey?sort_by=title&sort_order=DESC.

usgs.gov/twri9A.

Hughes, J.D., Langevin, C.D., and Brakefield-Goswami, Linzy, 2010, Effect of hypersaline cooling canals on aquifer salinization: Hydrogeology Journal, v. 18, p. 25-38.

Appendix 1 Appendix 15 Appendix 1. Estimation of Chloride Concentrations at Wells Where Conductivity Profiles Were Used for Monitoring At locations where water conductivity profiles were less), but 37 percent have open intervals of 8 to 40 m (Prinos, used for monitoring, chloride concentrations were estimated 2017). The long open-interval wells are not ideal for salinity by using a relation based on a linear regression of the chloride monitoring for the reasons summarized in Prinos (2013) and concentration and specific conductance of 16,184 water Prinos and Valderrama (2015), but they are the only wells samples collected between November 28, 1940, and available at some locations.

September 26, 2016, from 178 monitoring sites sampled by the USGS in southern Florida (table 1-1). All of these sample results are available through the USGS National Water Information System website (U.S. Geological Survey, 2016). References Cited The relation is expressed as Carlson, Glenn, [n.d.], Specific conductance as an output for cc = 0.3458sc 176.32 (1) conductivity readings: In-Situ Inc., Technical Note 9, 2 p.,

accessed March 6, 2017, at https://in-situ.com/wp-content/

where uploads/2015/01/Specific-Conductance-as-an-Output-Unit-cc is the chloride concentration in milligrams per for-Conductivity-Readings-Tech-Note.pdf.

liter, and sc is the specific conductance in microsiemens Prinos, S.T., 2013, Saltwater intrusion in the surficial aquifer per centimeter. system of the Big Cypress Basin, southwest Florida, and a proposed plan for improved salinity monitoring:

Conductance was converted to specific conductance using the U.S. Geological Survey Open-File Report 2013-1088, following relation (Carlson, [n.d.]). 58 p., accessed January 5, 2017, at https://pubs.usgs.gov/

of/2013/1088/.

sc = c/(1 + r(T 25)) (2)

Prinos, S.T., 2017, Data pertaining to mapping the where approximate inland extent of saltwater in the Biscayne c is the actual conductance measured in aquifer, in the Model Land Area of Miami-Dade County, microsiemens per centimeter, Florida, 2016: U.S. Geological Survey data release, T is the temperature of the sample in degrees http://dx.doi.org/10.5066/F7R78CF8.

Celsius, and r is the temperature correction coefficient for Prinos, S.T., and Valderrama, Robert, 2015, Changes in the sample. the saltwater interface corresponding to the installation of a seepage barrier near Lake Okeechobee, Florida:

The TSEMIL-derived vertical profiles of bulk U.S. Geological Survey Open-File Report 2014-1256, conductivity provide additional qualitative insights for 24 p., accessed January 5, 2017, at https://pubs.usgs.gov/

mapping, such as detection of any influxes of conductive of/2014/1256/.

water that do not correspond to the open interval of the well and temporal changes in the depth of the top of the saltwater U.S. Geological Survey, 2016, National Water Information interface. SystemWeb interface, accessed September 28, 2016, at The majority of the monitoring wells used for this http://dx.doi.org/10.5066/F7P55KJN.

analysis have short open intervals (about 1.5 meters [m] or

6 Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer, Miami-Dade County, Florida, 2016 Table 1-1. Listing of U.S. Geological Survey monitoring sites in southern Florida from which water samples were collected to evaluate specific conductance and chloride concentration.

[USGS, U.S. Geological Survey]

USGS station USGS station Site name Site name identifier identifier 262313080044401 PB -1457 255453080110801 G-3978 262209080044702 PB -1669 254601080150301 G-3977 261100080140401 G -1212 254156080172101 G -3607 261122080083401 G -1232 252814080244101 G -3698 260547080105801 G -2352 252652080244301 G -3699 260920080092201 G -2898 252650080252701 G -3855 260551080111901 G -2957 253253080221201 G -3885 261740080054101 G -2893 253527080195401 G -3886 255916080090401 G -1435 253924080174601 G -3887A 255910080085802 G -2294 253924080174602 G -3887B 255919080091202 G -2409 254542080145901 G -3888A 255919080091203 G -2410 254542080145902 G -3888B 255936080091701 G -2477 254542080145903 G -3888C 255936080091702 G -2478 253948080250701 G -3897 255916080092001 G -2965 254152080282601 G -3898 260037080100700 Hollywood Canal at Hollywood Blvd, 253419080223701 G -3899 Hollywood, FL 252718080264901 G -3900 260104080101300 Hollywood Canal at Johnson St, Hollywood, 252506080300601 G -3901 FL 252431080261001 G -3946D 260225080095800 Hollywood Canal at N29 Ave, Hollywood, FL 252431080261002 G -3946S 260212080112500 Hollywood Canal at N46 Ave, Hollywood, 255011080124501 G -3947 FL 255515080103601 G -3948D 260132080094900 Hollywood Canal at Taft St, Hollywood, FL 255515080103602 G -3948S 260041080093101 G -2425 255733080195601 G -3949D 260041080093102 G -2426 255733080195602 G -3949I 260120080093401 G -2441 255733080195603 G -3949S 260155080092002 G -2612 254824080155301 G -3964 260026080095801 G -2956 254500080162801 G -3965 254943080121501 F - 45 252719080253601 G -3966D 254841080164401 G - 571 252719080253602 G -3966S 255350080105801 G - 894 253335080213501 G -3967 254107080165201 G - 896 255315080111501 F - 279 254201080173001 G - 901 254828080161501 G - 354 254106080174601 G -1009B 254335080170501 G - 432 252947080235301 G -1180 254855080163701 G - 548 254813080161501 G -1351 253652080183701 G - 939 254833080155801 G -1354 253202080232601 G -3162 255222080123001 G -3224 253831080180204 G -3313C 254457080160301 G -3229 253831080180206 G -3313E 254946080172601 G -3250 255358080114101 G -3601 252714080260901 G-3976 255116080120601 G -3602

Appendix 17 Table 1-1. Listing of U.S. Geological Survey monitoring sites in southern Florida from which water samples were collected to evaluate specific conductance and chloride concentration.Continued

[USGS, U.S. Geological Survey]

USGS station USGS station Site name Site name identifier identifier 254908080125201 G -3603 260534080110801 G -2904 254722080152201 G -3604 262839081503100 L - 735 254629080143101 G -3605 262022081464201 L - 738 254341080174001 G -3606 263532081592202 L -1136 254108080170601 G -3608 263813081552801 L -2640 254005080171601 G -3609 263819081585801 L -2701 253819080183201 G -3610 263955082083102 L -2820 253710080184701 G -3611 263117082051002 L -2821 253457080195501 G -3612 264053081572501 L -4820 253024080231001 G -3615 262513081472002 L -5668R 253027080234701 G -3700 261926081454702 L -5745R 253214080224601 G -3701 264123080053801 PB - 809 253334080213601 G -3702 263044080035102 PB -1195 254822080125501 G -3704 262755080040101 PB -1707 255625080094901 G -3705 262803080041101 PB -1714 261302081473901 C - 489 263453080031501 PB -1717 261156081475801 C - 516 263633080031401 PB -1723 261002081483701 C - 525 265550080070701 PB -1732 261018081484101 C - 526 265611080080201 PB -1733 261200081483001 C - 528 265006081042502 GL - 334I 260549081441901 C - 600 265006081042501 GL - 334S 261802081354801 C - 688 265006081042503 GL - 334D 261347081351201 C - 953 264912081024602 GL -332S 261620081464402 C -1004R 264912081024601 GL -332 261604081480901 C -1059 264843080591502 GL - 333I 261311081480101 C -1061 264843080591501 GL - 333S 260137081375901 C -1063 264843080591503 GL - 333D 262228081361902 C -1080 264532080545902 HE -1145S 261403080070801 G -2149 264532080545901 HE -1145 260342080115902 G -2264 264343080511601 PB -1843S 261446080062801 G -2445 264343080511602 PB -1843I 261724080054603 G -2693 264343080511603 PB -1843D 260242080101101 G -2697 264154080480302 PB -1822S 261643080055901 G -2752 264154080480301 PB -1822 261740080054101 G -2893 264050080435502 PB -1842I 261304080072501 G -2896 264050080435501 PB -1842S 261030080083301 G -2897 264050080435503 PB -1842D 260804080092701 G -2899 264814080414302 PB -1819S 260325080113901 G -2900 264814080414301 PB -1819 260638080104801 G -2902 264926080394503 PB -1848D 255843080090901 G -2903 264930080394703 PB -1847D

8 Map of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer, Miami-Dade County, Florida, 2016 Table 1-1. Listing of U.S. Geological Survey monitoring sites in southern Florida from which water samples were collected to evaluate specific conductance and chloride concentration.Continued

[USGS, U.S. Geological Survey]

USGS station USGS station Site name Site name identifier identifier 265138080375802 PB -1818S 265428080364501 PB -1816 265138080375801 PB -1818 265519080364902 PB -1815S 265142080374202 PB -1817S 265519080364901 PB -1815 265142080374201 PB -1817 265701080363103 PB -1844D 265208080373902 PB -1845I 265701080363102 PB -1844I 265208080373901 PB -1845S 265701080363101 PB -1844S 265208080373903 PB -1845D 265839080365202 M -1369I 265200080373101 PB -1846S 265839080365201 M -1369D 265428080364502 PB -1816S For more information about this publication, contact:

Director, Caribbean-Florida Water Science Center U.S. Geological Survey 4446 Pet Lane, Suite 108 Lutz, FL 33559 (813) 498-5000 Or visit the USGS Caribbean-Florida Water Science Center website at:

https://fl.water.usgs.gov Publishing support provided by Lafayette Publishing Service Center

PrinosMap of the Approximate Inland Extent of Saltwater at the Base of the Biscayne Aquifer, Miami-Dade County, Florida, 2016SIM 3380 ISSN 2329-132X (online) https://doi.org/10.3133/sim3380

WITTKOP PARK HARRIS PARK Miami-Dade County Distance from Coast: 6.5 miles Salt Intrusion Extent NEWTON FLORIDA CITY Florida City Canal FLORIDA KEYS AQUADUCT AUTHORITY EVERGLADES LABOR CAMP rd Ca So un dR oa db ow orr can al Salt Intrusion at the Base of the Biscayne Aquifer (1,000 mg/L chlorides)

Distance from US Geological Survey Data Coast: 10.6 miles 2016 Salt Intrusion Line 2011 Salt Intrusion Line 1995 Salt Intrusion Line 0 0.5 1 2 3 4 5 6 Miles Wellfield Protection Areas Saltline_trends_20180430.mxd - GMB - May 7, 2018

DERM Class I Permit Required Monitoring in L31E Canal June 2015 to May 29, 2018 Summary of Chloride Results 18000 16000 14000 12000 10000 mg/L 8000 6000 4000 2000 0

TPSWC1B TPSWC2B TPSWC3B MDC Chapter 24 Standard (500 mg/L, waste shall not increase natural background more than 10 percent)

Model Lands Surface Water Specific Conductance L-31E borrow canal and Model Lands South canal April 2018

.

L31E-B L31E-A Depth SpCond (u/s)

Depth SpCond (u/s)

T (0.25 m) 4835.1 T (0.41 m) 9100.7 M (1.021m) 9146.1 M (1.45m) 9097.6 B (2.176m) 8642 B (3.477m) 9793 L31E-B L31E-A I-1 I-1 Depth SpCond (u/s)

I-2 T (0.22 m) 9224.6 M (1.087m) 9245.4 I-2 B (2.117m) 8669.7 Depth SpCond (u/s)

T (0.49 m) 9336.1 M (1.7m) 9325.9 B (2.499m) 9130.6 L31E-C L31E-C Depth SpCond (u/s)

T (0.132m) 9462.3 M (1.549m) 9460.6 B (2.951m) 9322.3 L31E-D Depth SpCond (u/s)

T (0.24m) 21744.3 M (0.891m) 21588.7 B (1.841m) 21612.6 L31E-D I-3 I-3 EEL1 Depth SpCond (u/s)

Depth SpCond (u/s) T (0.071m) 21529.3 T (0.1m) 5408 M (1.493m) 21528.6 B (2.932m) 45473 EEL1 EEL2 L31E-E Spec ific Conductance Sampling Points L31E-E EEL2 Depth SpCond (u/s) Canals Depth SpCond (u/s)

T (0.079m) 21347 T (0.179m) 5934.9 M (0.956m) 21377.1 Miami-Dade EEL Program B (1.956m) 22714.6 SFWMD I-4 Florida Power and Light L31E-F I-4 L31E-F Depth SpCond (u/s) Rock mining Lands and Associated Mitigation Depth SpCond (u/s) T (0.299m) 21580 T (0.179m) 21444.5 M (0.939m) 21534.6 State of Florida M (0.707m) 21424.5 B (2.077m) 23692.6 B (1.653m) 31860.2 Federal Private Rock mining Lands and Associated Mitigation Florida Power and Light Miles 0 0.75 1.5 3 4.5 6 Rock mining Lands and Associated Mitigation

Model Lands Hydrology and FPL Everglades Mitigation Bank L-31E Culvert Weir Operation RER-DERM Water Resources Coordination and Education Division February 15, 2018

Model Lands Hydrology Isolated by Roads/Levees No Connection to Regional Canal System Rain-driven

Interceptor Ditch pumps Model Lands Hydrology Palm Drive culverts S-20 (restoration)

S-20 Everglades Mitigation Bank L-31E culvert weirs Interceptor Ditch pumps

Model Lands Hydrology and S-20 Operations Central and Southern Florida Project for Flood Control and Other Purposes Master Water Control Manual - East Coast Canals - Volume 5

Model Lands Hydrology and S-20 Operations C&SF Project Structure Manual, S-20 Section (revised 1/16/2003):

Model Lands Groundwater Control Elevations Current Water Management 3.5 ft 3.0 ft Water Levels that Support Environmental Services Water Elevation (ft NGVD) 2.5 ft Optimum S-20 Headwater Elevation (per C&SF Master Manual)

Existing S-20 Operations for Flood Control, Salt 2.0 ft Intrusion Control Local Wetland Ground Elevation (1.8 ft NGVD at TPGW-4, close to both S-20 and EMB culverts) 1.5 ft FPL Everglades Mitigation Bank L-31E Culvert Weir Operations FPL-EMB culvert operations, per Special Condition 15(d) of FDEP Permit 0193232-001, Mod 055 (June 25, 2013):

1.0 ft

• Preliminarily, during the wet season (May - September), the L-31-E control structures shall be set at an elevation that is at least 0.2 feet lower than the 0.5 ft water level invert setting of the S-20 structure.

Mean Sea Level

• During the dry season (October -

April), they will be set at 0.1 feet lower than the S-20 control elevation setting.

Model Lands Groundwater Stages Healthy Sawgrass Prairie:

Existing Conditions vs. Healthy Ecology 8-10 months Hydroperiod#

3.5 ft TPGW-4S, August 31, 2010 - February 2, 2015 2011: <5 months 3.0 ft 2012: <8 months Water Elevation (ft NGVD) 2013: <4 months 2014: <5 months 2.5 ft Existing S-20 Operations 2.0 ft FPL L-31E 1.5 ft Culvert Weir Operations 1.0 ft 0.5 ft Mean Sea Level

1. Wetzel2001. Plant Community Parameter Estimates and Documentation for the Across 30-Sep-10 31-Jan-11 30-Sep-11 29-Feb-12 30-Sep-12 31-Jan-13 30-Sep-13 31-Jan-14 31-Aug-10 31-Oct-10 30-Nov-10 31-Dec-10 31-Mar-11 30-Apr-11 31-May-11 30-Jun-11 31-Jul-11 31-Aug-11 31-Oct-11 30-Nov-11 31-Dec-11 31-Jan-12 31-Mar-12 30-Apr-12 31-May-12 30-Jun-12 31-Jul-12 31-Aug-12 31-Oct-12 30-Nov-12 31-Dec-12 31-Mar-13 30-Apr-13 31-May-13 30-Jun-13 31-Jul-13 31-Aug-13 31-Oct-13 30-Nov-13 31-Dec-13 31-Mar-14 30-Apr-14 31-May-14 30-Jun-14 31-Jul-14 31-Aug-14 30-Sep-14 31-Oct-14 30-Nov-14 31-Dec-14 31-Jan-15 Trophic Level System Simulation (ATLSS). Data Report Prepared for 28-Feb-11 28-Feb-13 28-Feb-14 the ATLSS Project Team, University of Tennessee-Knoxville, 59Pp.

Water Level (ft NGVD29) Nearby Wetland Ground Elevation (1.8 ft NGVD)

C-111 Spreader Canal Western CERP Project February 2012 - Project Construction completed under SFWMD state-expedited program June 10, 2014 Congressional Authorization (WRDA 2014)

Features:

Frog Pond Detention Area Aerojet Canal Features Plugs in C-110 Operational Changes at S-18C Plug at S-20A Operational Changes at S-20

Model Lands Groundwater Control Elevations CERP Restoration Vision vs. Current Water Management 3.5 ft CERP Restoration, per C-111 3.0 ft CERP Restoration Vision Spreader Canal Western Project FEIS and BBCW Alt O Conceptual Water Elevation (ft NGVD)

Design, Army Corps of Engineers):

• S-20 open and close triggers to be 2.5 ft increased 0.5 foot

• 4 pump stations on Florida City Local Wetland Existing S-20 Operations Canal pump up to 150 cfs into the Model Lands 2.0 ft Ground Elevation 1.5 ft FPL Everglades Mitigation Bank L-31E Culvert Weir Operations 1.0 ft 0.5 ft Mean Sea Level

C-111 Spreader Canal Western CERP Project Page xii:

OUR CONCLUSION: HYDROPERIOD RESTORATION IS DEPENDENT ON A REDUCTION IN OVERDRAINAGE CAUSED BY CANAL INFRASTRUCTURE

C-111 Spreader Canal Western CERP Project

C-111 Spreader Canal Western CERP Project

C-111 Spreader Canal Western CERP Project Army Corps Permit for construction of the FPL Everglades Mitigation Bank:

FPL L-31E Culvert Elevations Gate elevations were raised from 1.8 to 2.2 ft NGVD per DERM Consent Agreement (Condition 17(c)(i):

Raise control elevations in the Everglades Mitigation Bank. Within 30 days of the effective date of this Consent Agreement, FPL shall raise the control elevations of the FPL Everglades Mitigation Bank ("EMB") culvert weirs to no lower than 0.2 feet lower than the 2.4 foot trigger of the S-20 structure and shall maintain this elevation.

After the first year of operation, FPL shall evaluate the change .in control elevation, in regards to improvements in salinity, water quality, and lift in the area, and if FPL determines that the change in control elevations is not effective, or that FPL is negatively impacted in receiving mitigation credits as a result of this action, FPL will consult with DERM and propose potential alternatives.

FPL EMB L-31E Culvert Elevations FPL Annual Monitoring Report, Everglades Mitigation Bank Phase II (January 2018)

Stage (ft NGVD) 0 0.5 1 1.5 2 2.5 3 3.5 4 9/1/2010 11/1/2010 1/1/2011 3/1/2011 5/1/2011 7/1/2011 9/1/2011 11/1/2011 1/1/2012 3/1/2012 5/1/2012 7/1/2012 9/1/2012 11/1/2012 1/1/2013 3/1/2013 5/1/2013 7/1/2013 9/1/2013 11/1/2013 FPL Everglades Mitigation Bank (EMB) 1/1/2014 3/1/2014 5/1/2014 7/1/2014 9/1/2014 11/1/2014 1/1/2015 3/1/2015 5/1/2015 September 1, 2010 to September 30, 2017 7/1/2015 9/1/2015 11/1/2015 1/1/2016 3/1/2016 FPL- EMB Culverts raised Culvert Elevations and Water Levels in L-31 E Canal 5/1/2016 from 1.8 ft NGVD to 2.2 ft NGVD 7/1/2016 9/1/2016 per CA requirement, 11/1/2016 10/22/2015 through 4/30/2017 1/1/2017 3/1/2017 (information provided by FPL) 5/1/2017 7/1/2017 9/1/2017

Interceptor Ditch Estimated Dry Season Volume Pumped 2011 - 2016 (January through May) 1400 1200 1000 Volume Pumped (MG) 800 600 400 200 0

2011 2012 2013 2014 2015 2016 L-31E culvert gates were raised to 2.2 ft NGVD on October 22, 2015 and remained at 2.2 ft NGVD through April 30, 2017

Volume (MG) 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 1/1/2017 1/8/2017 1/15/2017 1/22/2017 1/29/2017 2/5/2017 2/12/2017 FPL- EMB Culverts raised from 1.8 ft 2/19/2017 2/26/2017 NGVD to 2.2 ft NGVD per CA requirement, 3/5/2017 3/12/2017 10/22/2015 through 4/30/2017 3/19/2017 3/26/2017 4/2/2017 (information provided by FPL) 4/9/2017 4/16/2017 4/23/2017 L-31E Stage vs. Interceptor Ditch Pumping 4/30/2017 5/7/2017 5/14/2017 5/21/2017 ID Daily Pumping Volume (MG) 5/28/2017 6/4/2017 6/11/2017 6/18/2017 6/25/2017 7/2/2017 January 1, 2017 to September 4, 2017 7/9/2017 7/16/2017 7/23/2017 7/30/2017 8/6/2017 8/13/2017 8/20/2017 8/27/2017 9/3/2017 0 1 2 3 0.5 1.5 2.5 Stage (ft NGVD)

Specific Conductance (µS/cm) 0.00 5,000 5.0 10,000 10.0 15,000 15.0 20,000 20.0 25,000 25.0 30,000 30.0 35,000 35.0 40,000 40.0 1/1/2017 1/1/2017 1/8/2017 1/11/2017 1/15/2017 1/21/2017 1/22/2017 1/29/2017 1/31/2017 2/5/2017 2/10/2017 2/12/2017 2/20/2017 2/19/2017 2/26/2017 3/2/2017 3/5/2017 3/12/2017 3/12/2017 TPSWC-1B Avg. Daily Sp. Cond. (uS/cm) 3/19/2017 3/22/2017 3/26/2017 4/1/2017 4/2/2017 4/9/2017 4/11/2017 4/16/2017 4/21/2017 4/23/2017 4/30/2017 5/1/2017 5/7/2017 5/11/2017 5/14/2017 5/21/2017 S-20 Avg. Daily Stage (ft NGVD) 5/21/2017 TPSWC-2B Avg. Daily Sp. Cond. (uS/cm) 5/28/2017 5/31/2017 6/4/2017 6/10/2017 January 1 to September 4, 2017 6/11/2017 6/18/2017 6/20/2017 6/25/2017 6/30/2017 7/2/2017 7/9/2017 7/10/2017 7/16/2017 7/20/2017 7/23/2017 7/30/2017 7/30/2017 8/6/2017 8/9/2017 TPSWC-3B Avg. Daily Sp. Cond. (uS/cm)

L-31E Canal Bottom Specific Conductance vs. Surface Water Stage 8/13/2017 8/19/2017 8/20/2017 8/27/2017 8/29/2017 9/3/2017 0

0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 Stage (ft NGVD)

L-31E Canal Uprate and Class I Permit Required Surface Water Monitoring Stations

mg/L 10,000.00 12,000.00 14,000.00 16,000.00 0.00 2,000.00 4,000.00 6,000.00 8,000.00 May 31 & Jun 1, 2015 Jun 15 & 16, 2015 Jun 29 & 30, 2015 Jul 13 & 14, 2015 Jul 27 & 28, 2015 TPSWC-1B August 10 & 11 Aug 24 & 25, 2015 Sept 8 & 9 2015 Sept 21 & 22 2015 Oct 5 to 7, 2015 Oct 19 & 20, 2015 Nov 2 & 4, 2015 TPSWC-2B Nov 16 to 19, 2015 Nov 30 to Dec3, 2015 Dec 14 & 15, 2015 Dec 28 & 29, 2015 Jan 11 & 12, 2016 Jan 25 & 26, 2016 Feb 8 & 9, 2016 TPSWC-3B Feb 22 & 23, 2016 Mar 7 & 8, 2016 Mar 21 & 22, 2016 April 4 & 5, 2016 April 18 & 19, 2016 May 2 & 3, 2016 May 16 & 17, 2016 May 31 to Jun 3, 2016 Jun 13 & 14, 2016 DERM Class I Permit Required Monitoring in L-31E Canal Jun 27 & 28, 2016 Jul 11 & 12, 2016 Jul 25 & 26, 2016 Aug 8 & 9, 2016 Aug 22 & 23, 2016 Sep 6 & 7, 2016 Sept. 19 & 20, 2016 Oct. 3 & 4, 2016 Oct. 17 & 18, 2016 Oct. 31 & Nov 1, 2016 Nov 14 & 15, 2016 Nov 28 & 29, 2016 Dec 12 & 13, 2016 Dec 27 & 28, 2016 June 2015 to January 17, 2018 Jan 9 & 10, 2017 Jan 23 & 24, 2017 Feb 6 & 7, 2017 Feb 20 & 21, 2017 Mar 6 & 7, 2017 Mar 20 & 21, 2017 Apr 3 & 4, 2017 Apr 24 & 25, 2017 May 8 & 9, 2017 May22 & 23, 2017 June 5 to 7, 2017 June 19 & 20, 2017 Jul 5 to 8, 2017 Summary of Chloride Results Jul 17 & 18, 2017 Jul 31 & Aug 1, 2017 Aug 14 & 15, 2017 Aug 28 & 29, 2017 Sep 26 to 28, 2017 9-Oct-17 Oct 23 & 24, 2017 Nov 6 & 7, 2017 MDC Chapter 24 Standard (500 mg/L, waste shall not increase natural background more than 10 percent)

Nov 21 & 22, 2017 Dec 4 & 5, 2017 Dec 18 & 19, 2017 Jan 2 & 3, 2018 Jan 16 & 17, 2018

L-31E Canal May 12, 2017 Physical Parameter Surface Water Quality Survey Monitoring sites (20 sites)

L-31E Canal Water Column Physical Parameter Survey Salinity Result Summary, May 12, 2017 25.00 20.00 15.00 Salinity (PSU) 23.41 10.00 19.21 5.00 10.65 3.65 4.37 3.65 0.00 0 to 1 ft. 1.01 to 7.99 ft. 8 to 9.25 ft.

Depth Below Surface (ft.)

Min Max

L-31E Canal Uprate Monitoring Tritium Results TPSWC-1B, TPSWC-1T, TPSWC-2B, TPSWC-2T, TPSWC-3B & TPSWC-3T 200.0 180.0 160.0 140.0 120.0 pCi/L 100.0 80.0 60.0 40.0 20.0 0.0 Mar-11 Jun/Jul 2010 Sep-10 Dec-10 Jun-11 Sep-11 Dec-11 Mar-12 Jun-12 Sep-12 Dec-12 Mar-13 Jun-13 Sep-13 Dec-13 Mar-14 Jun-14 Sep-14 Dec-14 Mar-15 Jun-15 Sep-15 Dec-15 Mar-16 TPSWC-1B TPSWC-1T TPSWC-2B TPSWC-2T TPSWC-3B TPSWC-3T

L-31E Canal Uprate Monitoring Tritium Result Summary L-31E Canal Top vs. Bottom (N = 84 for each level) 200 180 160 140 120 pCi/L 100 182 80 154 60 40 60.1 57.2 20 8 10.3 0

Min Max Average Top (1 ft. below water surface) Bottom (1 ft. above canal bottom) Agencies screening level threshold (20 pCi/L)

Model Lands Hydrology and FPL Culvert Operations Summary Per CERP, the Model Lands Basin is overdrained by the L-31 E and S-20 water control structure, with water levels occasionally dropping below sea level Overdrainage needs to be stopped to restore both wetland stage and hydroperiod per CERP The amount of drainage from the L-31 Canal is established by the elevation of the water in the L-31 E Canal. The water in the L-31 E canal is drained through FPLs culverts to the stage established by these adjustable culvert weirs when the S-20 structure is closed.

FPLs preferred setting for L-31 E canal water level at 1.8 ft NGVD is 1.1 feet lower than the planned CERP open trigger setting and 0.6 feet lower than the planned close trigger.

EMB culvert weir settings at 2.2 ft NGVD reduces overdrainage of the basin CERP authorizes a change in S-20 operations to increase trigger stages by 0.5 ft in order to reduce overdrainage in the Model Lands The S-20 operations change has agency support at local, state, and federal levels The S-20 operations change is expected to make additional water available for release through the FPL culverts - a win-win for all parties

L31E Canal Average Daily Salinity at the Bottom August 30, 2010 to July 16, 2018 30 25 20 Salinity (PSU) 15 10 5

0 TPSWC1B Avg Daily Salinity (PSU) TPSWC2B Avg Daily Salinity (PSU) TPSWC3B Avg Daily Salinity (PSU)

L31E Canal Average Daily Salinity Profiles January 1 to July 16, 2018 30 25 20 PSU 15 10 5

0 TPSWC1T Avg Daily Salinity (PSU) TPSWC1B Avg Daily Salinity (PSU) TPSWC2T Avg Daily Salinity (PSU)

TPSWC2B Avg Daily Salinity (PSU) TPSWC3T Avg Daily Salinity (PSU) TPSWC3B Avg Daily Salinity (PSU)

Model Lands Groundwater Control Elevations Current Water Management 3.5 ft 3.0 ft Water Levels that Support Environmental Services Water Elevation (ft NGVD) 2.5 ft Optimum S-20 Headwater Elevation (per C&SF Master Manual)

Existing S-20 Operations for Flood Control, Salt 2.0 ft Intrusion Control Local Wetland Ground Elevation (1.8 ft NGVD at TPGW-4, close to both S-20 and EMB culverts) 1.5 ft FPL Everglades Mitigation Bank L-31E Culvert Weir Operations FPL-EMB culvert operations, per Special Condition 15(d) of FDEP Permit 0193232-001, Mod 055 (June 25, 2013):

1.0 ft

• Preliminarily, during the wet season (May - September), the L-31-E control structures shall be set at an elevation that is at least 0.2 feet lower than the 0.5 ft water level invert setting of the S-20 structure.

Mean Sea Level

• During the dry season (October -

April), they will be set at 0.1 feet lower than the S-20 control elevation setting.

Model Lands Groundwater Stages Healthy Sawgrass Prairie:

Existing Conditions vs. Healthy Ecology 8-10 months Hydroperiod#

3.5 ft TPGW-4S, August 31, 2010 - February 2, 2015 2011: <5 months 3.0 ft 2012: <8 months Water Elevation (ft NGVD) 2013: <4 months 2014: <5 months 2.5 ft Existing S-20 Operations 2.0 ft FPL L-31E 1.5 ft Culvert Weir Operations 1.0 ft 0.5 ft Mean Sea Level

1. Wetzel2001. Plant Community Parameter Estimates and Documentation for the Across 30-Sep-10 31-Jan-11 30-Sep-11 29-Feb-12 30-Sep-12 31-Jan-13 30-Sep-13 31-Jan-14 31-Aug-10 31-Oct-10 30-Nov-10 31-Dec-10 31-Mar-11 30-Apr-11 31-May-11 30-Jun-11 31-Jul-11 31-Aug-11 31-Oct-11 30-Nov-11 31-Dec-11 31-Jan-12 31-Mar-12 30-Apr-12 31-May-12 30-Jun-12 31-Jul-12 31-Aug-12 31-Oct-12 30-Nov-12 31-Dec-12 31-Mar-13 30-Apr-13 31-May-13 30-Jun-13 31-Jul-13 31-Aug-13 31-Oct-13 30-Nov-13 31-Dec-13 31-Mar-14 30-Apr-14 31-May-14 30-Jun-14 31-Jul-14 31-Aug-14 30-Sep-14 31-Oct-14 30-Nov-14 31-Dec-14 31-Jan-15 Trophic Level System Simulation (ATLSS). Data Report Prepared for 28-Feb-11 28-Feb-13 28-Feb-14 the ATLSS Project Team, University of Tennessee-Knoxville, 59Pp.

Water Level (ft NGVD29) Nearby Wetland Ground Elevation (1.8 ft NGVD)

Model Lands Surface Water Specific Conductance L-31E borrow canal and Model Lands South canal April 2018

.

L31E-D I-3 EEL2 EEL1 Depth SpCond (u/s) Depth SpCond (u/s)

T (0.179m) 5934.9 T (0.1m) 5408 EEL2 EEL1 L31E-E I-4 L31E-F Specific Conductance Sampling Points Canals Miami-Dade EEL Program SFWMD Florida Power and Light Rockmining Lands and Associated Mitigation State of Florida Federal Private Rockmining Lands and Associated Mitigation Florida Power and Light Miles 0 0.2 0.4 0.8 1.2 1.6 Rockmining Lands and Associated Mitigation

Contours Based On Deep Well Tritium Results MIAMI-DADE From the March 2013 Quarterly Sampling COUNTY IBr i ^ ,=.V u i

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