ML18213A432
| 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: |
| 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 701 NW 1st Court, 4th Floor Miami, Florida 33136-3912 T 305-372-6754 F 305-372-6759 miamidade.gov MIAMI-DADE COUNTY Carlos A. Gimenez, Mayor July 18, 2018 Lea Crandall, Clerk of the Department Office of General Counsel Florida Department of Environmental Protection 3900 Commonwealth Boulevard Tallahassee. Florida 32399-3000 CERTIFIED MAIL NO 7001 2510 0001 1765 4022 RETURN RECEIPT REQUESTED Timothy Rach, Program Administrator Submerged Lands and Environmental Resources Coordination Program Florida Department of Environmental Protection Bob Martinez Center 2600 Blair Stone F :oad MS 2500 Tallahassee, Florida 32399-2400 CERTIFIED MAIL NO 7001 2510 0001 1765 4176 RETURN RECEIPT REQUESTED 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. 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. 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. 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.
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 0.
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 SIN3 l/\\l H0V11V
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 1/1/2008 7/1/2008 1/1/2009 7/1/2009 1/1/2010 7/1/2010 1/1/2011 7/1/2011 1/1/2012 7/1/2012 1/1/2013 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 Stage (ft NGVD)
Model Lands Basin L-31E Water Levels 1/1/2000 - 6/30/2018 S-20 Stage (ft NGVD)
Sea Level (0.67 ft NGVD)
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 FKS 9 48 FKS 7 98 FKS 6 51 FKS 5 31 FKS 1 57 G-1180 22 G-3167 65 FKS 2 763 G-3976 36 G-3900 31 G-3166 150 G-1603 643 FKS 4 3,150 FKS 3 7,375 G-3342 2,390 G-1264 8,300 FKS 8 10,050 G-3855 7,960 G-3698 2,830 TPGW-9L 25.2 TPGW-8L 46.2 TPGW-7L 2,750 TPGW-6L 7,570 G-3966S 5,610 G-3946D 5,780 G-3699 10,700 TPGW-5L 12,300 TPGW-4L 15,200 TPGW-3L 28,500 TPGW-2L 31,200 TPGW-1L 29,100 SWIM well 130 TPGW-14L 27,800 TPGW-13L 36,800 TPGW-12L 27,100 TPGW-11L 25,300 TPGW-10L 26,400 ACI-MW-15 2,480 ACI-MW-09 30.8 ACI-MW-05 47.4 ACI-MW-04 48.5 ACI-MW-03 17.8 ACI-MW-16 36.9 Florida Keys Aqueduct Authority Leisure City Florida City Wittkop Park Newton Redavo Homestead Airforce Base Naranja Park Harris Park Everglades Labor Camp Sec34-MW-02-FS FLORIDA Miami-Dade County Study area EXPLANATION Monitoring well name and chloride concentration, in milligrams per liter Well field Approximate inland extent of saltwater in 2011 (Prinos and others, 2014)
Approximation Dashed where data are insufficient Approximate inland extent of saltwater in 2016 Approximation Dashed where data are insufficient G-3698 2,830 Model Land Area la n
a C
0 1
1 C
Card Sound Barnes Sound Little Card Sound Biscayne Bay Cooling canal system ATLANTIC OCEAN 0
2 4 MILES 0
2 4 KILOMETERS 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 square kilometer (km2) 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)
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 The inland extent of saltwater at the base of the Biscayne aquifer in the Model Land Area of Miami-Dade County, Florida, was mapped in 2011. Since that time, the saltwater interface has continued to move inland. The interface is near several active well fields; therefore, an updated approximation of the inland extent of saltwater and an improved understanding of the rate of movement of the saltwater interface are necessary. A geographic information system was used to create a map using the data collected by the organizations that monitor water salinity in this area. An average rate of saltwater interface movement of 140 meters per year was estimated by dividing the distance between two monitoring wells (TPGW-7L and Sec34-MW-02-FS) by the travel time. The travel time was determined by estimating the dates of arrival of the saltwater interface at the wells and computing the difference. This estimate assumes that the interface is traveling east to west between the two monitoring wells. Although monitoring is spatially limited in this area and some of the wells are not ideally designed for salinity monitoring, the monitoring network in this area is improving in spatial distribution and most of the new wells are well designed for salinity monitoring. The approximation of the inland extent of the saltwater interface and the estimated rate of movement of the interface are dependent on existing data.
Improved estimates could be obtained by installing uniformly designed monitoring wells in systematic transects extending landward of the advancing saltwater interface.
Introduction Seawater began intruding the Biscayne aquifer of Miami-Dade County early in the 20th century because of a decline in the fresh groundwater level, estimated to have been 2.9meters (m) below predrainage conditions near Miami (Prinos and others, 2014). By 2011, approximately 1,200 square kilometers (km2) of the mainland part of the Biscayne aquifer were intruded by saltwater (Prinos and others, 2014). Intrusion of the Biscayne aquifer by saltwater is a concern because it can render the water unpotable in affected parts of the aquifer.
The maximum concentration of chloride allowed in drinking water is 250 milligrams per liter (mg/L; U.S. Environmental Protection Agency, 2014), whereas saltwater-intruded parts of the aquifer commonly have water with chloride concentrations of 1,000 mg/L or greater.
The inland extent of saltwater at the base of the Biscayne aquifer was last mapped by Prinos and others (2014) in 2011.
Since that time, saltwater has continued to intrude beneath the Model Land Area. This area is a relatively flat and poorly drained wetland area in southeastern Miami-Dade County that is bordered on the east and south sides by Biscayne Bay, Card Sound, Little Card Sound, and Barnes Sound. A system of canals, water control structures, and levees regulate the flow of surface water in this area. There is an extensive system of cooling canals in the eastern part of this area that has been hypersaline at times (Hughes and others, 2010).
In the Model Land Area, the saltwater interface is near several active well fields; therefore, an updated approximation of the inland extent of saltwater and an improved understanding of the rate of movement of the saltwater interface are necessary. The U.S. Geological Survey (USGS), in cooperation with Miami-Dade County, mapped the approximate inland extent of saltwater in the Model Land Area in 2016 and approximated the average rate of movement of the 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, forecasting, and securing freshwater for Americas future.
The purpose of this report is to provide a map of the saltwater interface (2016), an estimate of the rate of interface movement given the dates of arrival at two wells, and a description of the methodologies used to arrive at these results. The analyses and estimates are based on available data from existing monitoring 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 Extent of the Saltwater Interface The approximate inland extent of saltwater in the Biscayne aquifer was determined by using (1) chloride concentration and specific conductance of water samples collected from monitoring wells, (2) water conductivity profiles collected in long open-interval wells, and (3) time-series electromagnetic-induction log (TSEMIL) datasets collected in polyvinyl-chloride-cased monitoring wells. This information was provided by EAS Engineering, Inc., the Florida Keys Aqueduct Authority, the Florida Power & Light Company, the South Florida Water Management District (SFWMD), and the USGS. Almost all of the data provided by the SFWMD for this study area had been collected by the other four organizations, so they are mostly redundant. The information was entered into a geographic information system (GIS) for analysis and mapping. Data used to make the map are available as a data release (Prinos, 2017).
Sampling, analysis, and quality assurance procedures of the organizations collecting salinity data in the study area vary.
Procedures used by the Florida Power & Light Company for sampling and quality assurance are described in the Turkey 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 Department of Environmental Protection, the Florida Power
& Light Company, and the SFWMD and was approved by the SFWMD. Procedures for sampling by the USGS are generally based on those described in the USGS field manual, but procedures have been modified for expediency and efficacy of routine, long-term saltwater intrusion monitoring (U.S. Geological Survey, variously dated; Lee Massey, U.S.
Geological Survey, written commun., March 7, 2017). EAS Engineering, Inc., and the Florida Keys Aqueduct Authority base their sampling on the specifications of the Florida Department of Environmental Protection (Florida Department of Environmental Protection, 2008). To ensure the quality of analyzed samples, the USGS laboratory participates in the Branch of Quality Systems Standard Reference Sample Semi-Annual Proficiency Testing Project. EAS Engineering, Inc.,
and the Florida Power & Light Company use laboratories that are certified through the National Environmental Laboratory Accreditation Program. Participation in this accreditation program likely assures that sample analyses are accurate; however, the USGS cannot completely verify this accuracy without reviewing the results of the accreditation testing for each laboratory used.
The approximate saltwater interface is represented by the 1,000-mg/L isochlor at the base of the Biscayne aquifer. The word approximate is used because the spatial distribution of monitoring wells is generally insufficient to create a precise representation. The accuracy and precision of this approximation is best evaluated on a location-by-location basis, based on the available monitoring wells. The locations of the monitoring wells and the chloride concentration values are shown on the map (sheet 1, available at https://doi.
org/10.3133/sim3380). The line depicting the approximate inland extent of saltwater is dashed where the monitoring well distribution is insufficient to create a reasonably accurate and precise approximation.
The TSEMIL-derived vertical profiles of bulk conductivity provide additional qualitative insights for mapping, such as detection of any influxes of conductive water that do not correspond to the open interval of the well and temporal changes in the depth of the top of the saltwater interface. Where water conductivity profiles were used for monitoring, chloride concentrations were estimated by using a relation based on a linear regression of the chloride concentration and specific conductance as described in appendix 1.
The majority of the monitoring wells used for this analysis have short open intervals (about 1.5 meters [m] or less), but 37 percent have open intervals of 8 to 40 m (Prinos, 2017). The long open-interval wells are not ideal for salinity monitoring for the reasons summarized in Prinos (2013) and Prinos and Valderrama (2015), but they are the only wells available at some locations.
Approximating the Rate of Movement of the Saltwater Interface The saltwater interface in the study area is advancing at an estimated average rate of 140 meters per year (m/yr).
This estimate is based on limited data because there are few wells in this area where the date of arrival of the saltwater interface can be ascertained. Most wells were installed either after the saltwater interface had already passed the location or where the saltwater interface has not yet arrived. The estimate is based on data from monitoring wells Sec34-MW-02-FS and TPGW-7L, monitored by EAS Engineering, Inc., and the Florida Power & Light Company, respectively.
Data from well TPGW-7L and selected conductance profiles from well Sec34-MW-02-FS are available in Prinos (2017).
Well TPGW-7L is open to the aquifer from 24 to 26 m below land surface (bls), which is near the depth of the base of the Biscayne aquifer at this location (Fish and Stewart, 1991). The chloride concentration in water samples from well TPGW-7L increased from 180 to 825 mg/L between December 3, 2013, and March 11, 2014, and from 825 to 1,300 mg/L between March 11, 2014, and June 9, 2014.
Water conductance profiles were collected from well Sec34-MW-02-FS. The maximum conductance of the profiles was found at a depth of about 25 m bls. Using equations 1 and 2 (appendix 1), conductance values measured at this depth equate to chloride concentrations of about 190, 530, 930, and 1,400 mg/L for November 12, 2007, January 15, 2008, April 4, 2008, and May 15, 2008, respectively.
Monitoring Network Improvements 3 The average rate of saltwater interface movement was estimated by dividing the distance between the wells (830 m) by the difference between the interpolated dates of arrival of chloride concentrations of 250 and 1,000 mg/L at each well. The interpolated dates of arrival at well Sec34-MW-02-FS were November 22, 2007, and April 8, 2008, for concentrations of 250 and 1,000 mg/L, respectively.
The interpolated dates of arrival at well TPGW-7L were December13, 2013, and April 13, 2014, for concentrations of 250 and 1,000 mg/L, respectively. Given these dates and the distance between these wells, the estimated rate of movement of the front is 137 m/yr based on a chloride concentration of 250mg/L, and the estimated rate based on a concentration of 1,000 mg/L is 138 m/yr. These estimates can be rounded to an average estimate of 140 m/yr. This rate of movement was used to help interpolate the location of the 1,000-mg/L isochlor in the Model Land Area.
This estimate assumes that the direction of front movement is parallel to a line passing through these two well locations, and that the rate of front movement is constant.
Use of this rate for interpolating the position of the saltwater interface elsewhere in the study area assumes that (1) effective porosity is uniform throughout this area, (2) direction of front movement is east to west, and (3) that the rate of front movement is the same throughout this area. Additional monitoring is needed to evaluate these assumptions (see Monitoring Network Improvements section of this report).
Given the stated assumptions, the saltwater interface may move under the Newton well field by 2026. This estimate of future movement may be conservative because withdrawals from the well field may influence the rate and direction of travel.
Monitoring Network Improvements Within the map, the line depicting the approximation of the inland extent of the saltwater interface is dashed near the Card Sound Road Canal and in the area around the C-110 Canal because there were insufficient data for an accurate delineation of the interface. These areas were previously mapped by using helicopter electromagnetic surveys (Fitterman and Prinos, 2012) and time-domain electromagnetic soundings (Fitterman and others, 2011).
Monitoring in these areas currently consists of only a few wells that are too far from the expected current location of the interface to provide relevant information. Monitoring near the edge of the elongated extension of saltwater that had intruded along the Card Sound Road Canal (Prinos and others, 2014) is almost nonexistent.
Given the rate of movement of the saltwater interface estimated in this investigation, the chloride concentrations ofsamples from some of the monitoring wells on the freshwater side of the interface may not exceed 1,000 mg/L for many years. Monitoring well FKS 9, for example, is 0.86km from the estimated location of the saltwater interface. The 1,000-mg/L isochlor may not arrive at this well until 2023, if the rate of movement of the saltwater interface proceeds at the average rate estimated in this study. Better estimates of the rates of movement are needed before 2023, particularly because the rate of movement may not be constant.
Monitoring well FKS 5 is even farther from the approximated location of the saltwater interface than well FKS 9. The rate and direction of movement of the saltwater interface near well FKS 5 are unknown. If the rate of movement were the same as that between wells Sec34-MW-02-FS and TPGW-7L, the 1,000-mg/L isochlor may not reach this well for 26 years if the interface moves northward, or 17 years if the interface moves westward. Water managers would most likely need to have a better understanding of the location of the saltwater interface, its rate of movement, and direction of movement than currently provided near FKS 5.
Differences in the design, placement, quality of chemical analyses, and type of monitoring can add uncertainty to this analysis. The analysis of the rate of movement of the saltwater interface between monitoring wells Sec34-MW-02-FS and TPGW-7L, for example, required a number of estimations, including the relation between specific conductance and chloride, the relation between pumped water samples and in situ measurements of conductance, and the conversion of conductance to specific conductance. These relations and conversions increase uncertainty.
Some monitoring wells, such as well Sec34-MW-02-FS and many of the wells monitored by the Florida Keys Aqueduct Authority, are designed to monitor the depth of the top of the saltwater interface through the collection of water 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 and Valderrama, 2015). Although several organizations base their sampling on the Standard Operating Procedures of the Florida Department of Environmental Protection, Prinos (2013) states that these procedures call for sampling of long open-interval wells by pumping from near the top of the water column or top of the open interval, which could result in samples that are not representative of maximum salinity in the aquifer. Uncertainty is also increased because some analyses are performed in the field as opposed to in a laboratory that participates in a quality assurance testing program (see the Mapping the Approximate Inland Extent of the Saltwater Interface section of this report).
Estimates of the rate of movement of the interface could be improved by placing monitoring wells along a transect, spaced at distances that would allow timely detection of any variations in the rate of movement of the saltwater interface, and parallel to the direction of movement of the interface. If four or five such transects were installed in the county, the resulting data could be used to evaluate spatial differences in the rates of movement of the saltwater interface at locations 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 how the depth of the interface is changing. Using consistent monitoring methods at wells in each transect could reduce the uncertainty in the estimated rate of movement.
References Cited Fish, J.E., and Stewart, Mark, 1991, Hydrogeology of the surficial aquifer system, Dade County, Florida: U.S.
Geological Survey Water-Resources Investigations Report 90-4108, 50 p., 11 sheets.
Fitterman, D.V., Deszcz-Pan, Maria, and Prinos, S.T., 2012, Helicopter electromagnetic survey of the Model Land Area, southeastern Miami-Dade County, Florida: U.S.
Geological Survey Open-File Report 2012-1176, 77 p.,
39pls., accessed January 5, 2017, at https://pubs.usgs.gov/
of/2012/1176/.
Fitterman, D.V., and Prinos, S.T., 2011, Results of time-domain electromagnetic soundings in Miami-Dade and southern Broward Counties, Florida: U.S. Geological Survey Open File Report 2011-1299, 289 p., accessed January 5, 2017, at https://pubs.usgs.gov/of/2011/1299/.
Florida Department of Environmental Protection, 2008, Groundwater sampling: Florida Department of Environmental Protection, Standard Operating Procedures, DEP-SOP-001/01 FS2200, 26 p., app., accessed February10, 2017, at http://www.dep.state.fl.us/Water/sas/
sop/sops.htm.
Florida Power & Light Company, 2011, Quality Assurance Project PlanTurkey Point Monitoring Project: Florida Power & Light Company, 170 p., 9 app., accessed February22, 2017, at https://www.sfwmd.gov/documents-by-tag/fpltpsurvey?sort_by=title&sort_order=DESC.
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.
Prinos, S.T., 2013, Saltwater intrusion in the surficial aquifer system of the Big Cypress Basin, southwest Florida, and a proposed plan for improved salinity monitoring:
U.S. Geological Survey Open-File Report 2013-1088, 58p., accessed January 5, 2017, at https://pubs.usgs.gov/
of/2013/1088/.
Prinos, S.T., 2017, Data pertaining to mapping the approximate inland extent of saltwater in the Biscayne aquifer, in the Model Land Area of Miami-Dade County, Florida, 2016: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7R78CF8.
Prinos, S.T., and Valderrama, Robert, 2015, Changes in the saltwater interface corresponding to the installation of a seepage barrier near Lake Okeechobee, Florida:
U.S. Geological Survey Open-File Report 2014-1256, 24p., accessed January 5, 2017, at https://pubs.usgs.gov/
of/2014/1256/.
Prinos, S.T., Wacker, M.A., Cunningham, K.J., and Fitterman, D.V., 2014, Origins and delineation of saltwater intrusion in the Biscayne aquifer and changes in the distribution of saltwater in Miami-Dade County, Florida: U.S. Geological Survey Scientific Investigations Report 2014-5025, 101p.,
accessed January 5, 2017, at http://dx.doi.org/10.3133/
sir20145025.
U.S. Environmental Protection Agency, 2014, Secondary drinking water standards: Guidance for nuisance chemicals:
U.S. Environmental Protection Agency Report 816-f 079, accessed January 26, 2011, at http://water.epa.gov/
drink/contaminants/secondarystandards.cfm.
U.S. Geological Survey, variously dated, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book9, chaps. A1-A9, available online at http://pubs.water.
usgs.gov/twri9A.
Appendix 1 5 Appendix 1. Estimation of Chloride Concentrations at Wells Where Conductivity Profiles Were Used for Monitoring At locations where water conductivity profiles were usedfor monitoring, chloride concentrations were estimated by using a relation based on a linear regression of the chloride concentration and specific conductance of 16,184water samples collected between November 28, 1940, and 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).
The relation is expressed as cc = 0.3458sc 176.32
(1) where cc
is the chloride concentration in milligrams per liter, and sc
is the specific conductance in microsiemens per centimeter.
Conductance was converted to specific conductance using the following relation (Carlson, [n.d.]).
sc = c/(1 + r(T 25))
(2) where c
is the actual conductance measured in microsiemens per centimeter, T
is the temperature of the sample in degrees Celsius, and r
is the temperature correction coefficient for the sample.
The TSEMIL-derived vertical profiles of bulk conductivity provide additional qualitative insights for mapping, such as detection of any influxes of conductive water that do not correspond to the open interval of the well and temporal changes in the depth of the top of the saltwater interface.
The majority of the monitoring wells used for this analysis have short open intervals (about 1.5 meters [m] or less), but 37 percent have open intervals of 8 to 40 m (Prinos, 2017). The long open-interval wells are not ideal for salinity monitoring for the reasons summarized in Prinos (2013) and Prinos and Valderrama (2015), but they are the only wells available at some locations.
References Cited Carlson, Glenn, [n.d.], Specific conductance as an output for conductivity readings: In-Situ Inc., Technical Note 9, 2 p.,
accessed March 6, 2017, at https://in-situ.com/wp-content/
uploads/2015/01/Specific-Conductance-as-an-Output-Unit-for-Conductivity-Readings-Tech-Note.pdf.
Prinos, S.T., 2013, Saltwater intrusion in the surficial aquifer system of the Big Cypress Basin, southwest Florida, and a proposed plan for improved salinity monitoring:
U.S. Geological Survey Open-File Report 2013-1088, 58p., accessed January 5, 2017, at https://pubs.usgs.gov/
of/2013/1088/.
Prinos, S.T., 2017, Data pertaining to mapping the approximate inland extent of saltwater in the Biscayne aquifer, in the Model Land Area of Miami-Dade County, Florida, 2016: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7R78CF8.
Prinos, S.T., and Valderrama, Robert, 2015, Changes in the saltwater interface corresponding to the installation of a seepage barrier near Lake Okeechobee, Florida:
U.S. Geological Survey Open-File Report 2014-1256, 24p., accessed January 5, 2017, at https://pubs.usgs.gov/
of/2014/1256/.
U.S. Geological Survey, 2016, National Water Information SystemWeb interface, accessed September 28, 2016, at http://dx.doi.org/10.5066/F7P55KJN.
Appendix 1
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 identifier Site name 262313080044401 PB -1457 262209080044702 PB -1669 261100080140401 G -1212 261122080083401 G -1232 260547080105801 G -2352 260920080092201 G -2898 260551080111901 G -2957 261740080054101 G -2893 255916080090401 G -1435 255910080085802 G -2294 255919080091202 G -2409 255919080091203 G -2410 255936080091701 G -2477 255936080091702 G -2478 255916080092001 G -2965 260037080100700 Hollywood Canal at Hollywood Blvd, Hollywood, FL 260104080101300 Hollywood Canal at Johnson St, Hollywood, FL 260225080095800 Hollywood Canal at N29 Ave, Hollywood, FL 260212080112500 Hollywood Canal at N46 Ave, Hollywood, FL 260132080094900 Hollywood Canal at Taft St, Hollywood, FL 260041080093101 G -2425 260041080093102 G -2426 260120080093401 G -2441 260155080092002 G -2612 260026080095801 G -2956 254943080121501 F - 45 254841080164401 G - 571 255350080105801 G - 894 254107080165201 G - 896 254201080173001 G - 901 254106080174601 G -1009B 252947080235301 G -1180 254813080161501 G -1351 254833080155801 G -1354 255222080123001 G -3224 254457080160301 G -3229 254946080172601 G -3250 252714080260901 G-3976 USGS station identifier Site name 255453080110801 G-3978 254601080150301 G-3977 254156080172101 G -3607 252814080244101 G -3698 252652080244301 G -3699 252650080252701 G -3855 253253080221201 G -3885 253527080195401 G -3886 253924080174601 G -3887A 253924080174602 G -3887B 254542080145901 G -3888A 254542080145902 G -3888B 254542080145903 G -3888C 253948080250701 G -3897 254152080282601 G -3898 253419080223701 G -3899 252718080264901 G -3900 252506080300601 G -3901 252431080261001 G -3946D 252431080261002 G -3946S 255011080124501 G -3947 255515080103601 G -3948D 255515080103602 G -3948S 255733080195601 G -3949D 255733080195602 G -3949I 255733080195603 G -3949S 254824080155301 G -3964 254500080162801 G -3965 252719080253601 G -3966D 252719080253602 G -3966S 253335080213501 G -3967 255315080111501 F - 279 254828080161501 G - 354 254335080170501 G - 432 254855080163701 G - 548 253652080183701 G - 939 253202080232601 G -3162 253831080180204 G -3313C 253831080180206 G -3313E 255358080114101 G -3601 255116080120601 G -3602
Appendix 1 7 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 identifier Site name 254908080125201 G -3603 254722080152201 G -3604 254629080143101 G -3605 254341080174001 G -3606 254108080170601 G -3608 254005080171601 G -3609 253819080183201 G -3610 253710080184701 G -3611 253457080195501 G -3612 253024080231001 G -3615 253027080234701 G -3700 253214080224601 G -3701 253334080213601 G -3702 254822080125501 G -3704 255625080094901 G -3705 261302081473901 C - 489 261156081475801 C - 516 261002081483701 C - 525 261018081484101 C - 526 261200081483001 C - 528 260549081441901 C - 600 261802081354801 C - 688 261347081351201 C - 953 261620081464402 C -1004R 261604081480901 C -1059 261311081480101 C -1061 260137081375901 C -1063 262228081361902 C -1080 261403080070801 G -2149 260342080115902 G -2264 261446080062801 G -2445 261724080054603 G -2693 260242080101101 G -2697 261643080055901 G -2752 261740080054101 G -2893 261304080072501 G -2896 261030080083301 G -2897 260804080092701 G -2899 260325080113901 G -2900 260638080104801 G -2902 255843080090901 G -2903 USGS station identifier Site name 260534080110801 G -2904 262839081503100 L - 735 262022081464201 L - 738 263532081592202 L -1136 263813081552801 L -2640 263819081585801 L -2701 263955082083102 L -2820 263117082051002 L -2821 264053081572501 L -4820 262513081472002 L -5668R 261926081454702 L -5745R 264123080053801 PB - 809 263044080035102 PB -1195 262755080040101 PB -1707 262803080041101 PB -1714 263453080031501 PB -1717 263633080031401 PB -1723 265550080070701 PB -1732 265611080080201 PB -1733 265006081042502 GL - 334I 265006081042501 GL - 334S 265006081042503 GL - 334D 264912081024602 GL -332S 264912081024601 GL -332 264843080591502 GL - 333I 264843080591501 GL - 333S 264843080591503 GL - 333D 264532080545902 HE -1145S 264532080545901 HE -1145 264343080511601 PB -1843S 264343080511602 PB -1843I 264343080511603 PB -1843D 264154080480302 PB -1822S 264154080480301 PB -1822 264050080435502 PB -1842I 264050080435501 PB -1842S 264050080435503 PB -1842D 264814080414302 PB -1819S 264814080414301 PB -1819 264926080394503 PB -1848D 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 identifier Site name 265138080375802 PB -1818S 265138080375801 PB -1818 265142080374202 PB -1817S 265142080374201 PB -1817 265208080373902 PB -1845I 265208080373901 PB -1845S 265208080373903 PB -1845D 265200080373101 PB -1846S 265428080364502 PB -1816S USGS station identifier Site name 265428080364501 PB -1816 265519080364902 PB -1815S 265519080364901 PB -1815 265701080363103 PB -1844D 265701080363102 PB -1844I 265701080363101 PB -1844S 265839080365202 M -1369I 265839080365201 M -1369D 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
FLORIDA KEYS AQUADUCT AUTHORITY FLORIDA CITY WITTKOP PARK NEWTON HARRIS PARK EVERGLADES LABOR CAMP Saltline_trends_20180430.mxd - GMB - May 7, 2018 Salt Intrusion at the Base of the Biscayne Aquifer (1,000 mg/L chlorides)
US Geological Survey Data 2016 Salt Intrusion Line 2011 Salt Intrusion Line 1995 Salt Intrusion Line Wellfield Protection Areas Miami-Dade County Salt Intrusion Extent 0
1 2
3 4
5 6
0.5 Miles Florida City Canal Card Sound Road borrow canal Distance from Coast: 10.6 miles Distance from Coast: 6.5 miles
0 2000 4000 6000 8000 10000 12000 14000 16000 18000 mg/L DERMClassIPermitRequiredMonitoringinL31ECanal June2015toMay29,2018SummaryofChlorideResults TPSWC1B TPSWC2B TPSWC3B MDCChapter24Standard(500mg/L,wasteshallnotincreasenaturalbackgroundmorethan10percent)
I-2 I-1 I-4 I-3 EEL2 EEL1 L31E-F L31E-C L31E-B L31E-E L31E-D L31E-A 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 Rockmining Lands and Associated Mitigation Model Lands Surface Water Specific Conductance L-31E borrow canal and Model Lands South canal April 2018 Depth SpCond (u/s)
T (0.41 m) 9100.7 M (1.45m) 9097.6 B (3.477m) 9793 L31E-A Depth SpCond (u/s)
T (0.25 m) 4835.1 M (1.021m) 9146.1 B (2.176m) 8642 L31E-B Depth SpCond (u/s)
T (0.22 m) 9224.6 M (1.087m) 9245.4 B (2.117m) 8669.7 I-1 Depth SpCond (u/s)
T (0.49 m) 9336.1 M (1.7m) 9325.9 B (2.499m) 9130.6 I-2 Depth SpCond (u/s)
T (0.132m) 9462.3 M (1.549m) 9460.6 B (2.951m) 9322.3 L31E-C Depth SpCond (u/s)
T (0.24m) 21744.3 M (0.891m) 21588.7 B (1.841m) 21612.6 L31E-D Depth SpCond (u/s)
T (0.071m) 21529.3 M (1.493m) 21528.6 B (2.932m) 45473 I-3 Depth SpCond (u/s)
T (0.079m) 21347 M (0.956m) 21377.1 B (1.956m) 22714.6 L31E-E Depth SpCond (u/s)
T (0.299m) 21580 M (0.939m) 21534.6 B (2.077m) 23692.6 I-4 Depth SpCond (u/s)
T (0.179m) 21444.5 M (0.707m) 21424.5 B (1.653m) 31860.2 L31E-F Depth SpCond (u/s)
T (0.179m) 5934.9 EEL2 Depth SpCond (u/s)
T (0.1m) 5408 EEL1 0
1.5 3
4.5 6
0.75 Miles
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
Palm Drive culverts (restoration)
S-20 Everglades Mitigation Bank L-31E culvert weirs Interceptor Ditch pumps Model Lands Hydrology S-20 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):
Water Elevation (ft NGVD)
Model Lands Groundwater Control Elevations Current Water Management 0.5 ft 1.0 ft 1.5 ft 2.0 ft 2.5 ft 3.0 ft 3.5 ft Mean Sea Level FPL Everglades Mitigation Bank L-31E Culvert Weir Operations Existing S-20 Operations for Flood Control, Salt Intrusion Control FPL-EMB culvert operations, per Special Condition 15(d) of FDEP Permit 0193232-001, Mod 055 (June 25, 2013):
- 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 water level invert setting of the S-20 structure.
- During the dry season (October -
April), they will be set at 0.1 feet lower than the S-20 control elevation setting.
Local Wetland Ground Elevation (1.8 ft NGVD at TPGW-4, close to both S-20 and EMB culverts)
Water Levels that Support Environmental Services Optimum S-20 Headwater Elevation (per C&SF Master Manual)
31-Aug-10 30-Sep-10 31-Oct-10 30-Nov-10 31-Dec-10 31-Jan-11 28-Feb-11 31-Mar-11 30-Apr-11 31-May-11 30-Jun-11 31-Jul-11 31-Aug-11 30-Sep-11 31-Oct-11 30-Nov-11 31-Dec-11 31-Jan-12 29-Feb-12 31-Mar-12 30-Apr-12 31-May-12 30-Jun-12 31-Jul-12 31-Aug-12 30-Sep-12 31-Oct-12 30-Nov-12 31-Dec-12 31-Jan-13 28-Feb-13 31-Mar-13 30-Apr-13 31-May-13 30-Jun-13 31-Jul-13 31-Aug-13 30-Sep-13 31-Oct-13 30-Nov-13 31-Dec-13 31-Jan-14 28-Feb-14 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 TPGW-4S, August 31, 2010 - February 2, 2015 Water Level (ft NGVD29)
Nearby Wetland Ground Elevation (1.8 ft NGVD)
Water Elevation (ft NGVD)
Model Lands Groundwater Stages Existing Conditions vs. Healthy Ecology 0.5 ft 1.0 ft 1.5 ft 2.0 ft 2.5 ft 3.0 ft Existing S-20 Operations FPL L-31E Culvert Weir Operations Mean Sea Level 3.5 ft 2011: <5 months 2012: <8 months 2013: <4 months 2014: <5 months Healthy Sawgrass Prairie:
8-10 months Hydroperiod#
- Wetzel 2001. Plant Community Parameter Estimates and Documentation for the Across Trophic Level System Simulation (ATLSS). Data Report Prepared for the ATLSS Project Team, University of Tennessee-Knoxville, 59Pp.
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
Water Elevation (ft NGVD)
Model Lands Groundwater Control Elevations CERP Restoration Vision vs. Current Water Management 0.5 ft 1.0 ft 1.5 ft 2.0 ft 2.5 ft 3.0 ft 3.5 ft Mean Sea Level FPL Everglades Mitigation Bank L-31E Culvert Weir Operations Existing S-20 Operations CERP Restoration Vision CERP Restoration, per C-111 Spreader Canal Western Project FEIS and BBCW Alt O Conceptual Design, Army Corps of Engineers):
- S-20 open and close triggers to be increased 0.5 foot
- 4 pump stations on Florida City Canal pump up to 150 cfs into the Model Lands Local Wetland Ground Elevation
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)
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 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 7/1/2015 9/1/2015 11/1/2015 1/1/2016 3/1/2016 5/1/2016 7/1/2016 9/1/2016 11/1/2016 1/1/2017 3/1/2017 5/1/2017 7/1/2017 9/1/2017 Stage (ft NGVD)
September 1, 2010 to September 30, 2017 FPL-EMB Culverts raised from 1.8 ft NGVD to 2.2 ft NGVD per CA requirement, 10/22/2015 through 4/30/2017 (information provided by FPL)
FPL Everglades Mitigation Bank (EMB)
Culvert Elevations and Water Levels in L-31 E Canal
0 200 400 600 800 1000 1200 1400 2011 2012 2013 2014 2015 2016 Volume Pumped (MG)
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 Interceptor Ditch Estimated Dry Season Volume Pumped 2011 - 2016 (January through May)
0 0.5 1
1.5 2
2.5 3
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 2/19/2017 2/26/2017 3/5/2017 3/12/2017 3/19/2017 3/26/2017 4/2/2017 4/9/2017 4/16/2017 4/23/2017 4/30/2017 5/7/2017 5/14/2017 5/21/2017 5/28/2017 6/4/2017 6/11/2017 6/18/2017 6/25/2017 7/2/2017 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 Volume (MG)
Stage (ft NGVD)
ID Daily Pumping Volume (MG)
FPL-EMB Culverts raised from 1.8 ft NGVD to 2.2 ft NGVD per CA requirement, 10/22/2015 through 4/30/2017 (information provided by FPL)
L-31E Stage vs. Interceptor Ditch Pumping January 1, 2017 to September 4, 2017
0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 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 2/19/2017 2/26/2017 3/5/2017 3/12/2017 3/19/2017 3/26/2017 4/2/2017 4/9/2017 4/16/2017 4/23/2017 4/30/2017 5/7/2017 5/14/2017 5/21/2017 5/28/2017 6/4/2017 6/11/2017 6/18/2017 6/25/2017 7/2/2017 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 Stage (ft NGVD) 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 1/1/2017 1/11/2017 1/21/2017 1/31/2017 2/10/2017 2/20/2017 3/2/2017 3/12/2017 3/22/2017 4/1/2017 4/11/2017 4/21/2017 5/1/2017 5/11/2017 5/21/2017 5/31/2017 6/10/2017 6/20/2017 6/30/2017 7/10/2017 7/20/2017 7/30/2017 8/9/2017 8/19/2017 8/29/2017 Specific Conductance (µS/cm)
TPSWC-1B Avg. Daily Sp. Cond. (uS/cm)
TPSWC-2B Avg. Daily Sp. Cond. (uS/cm)
TPSWC-3B Avg. Daily Sp. Cond. (uS/cm)
L-31E Canal Bottom Specific Conductance vs. Surface Water Stage January 1 to September 4, 2017 S-20 Avg. Daily Stage (ft NGVD)
L-31E Canal Uprate and Class I Permit Required Surface Water Monitoring Stations
0.00 2,000.00 4,000.00 6,000.00 8,000.00 10,000.00 12,000.00 14,000.00 16,000.00 May 31 & Jun 1, 2015 Jun 15 & 16, 2015 Jun 29 & 30, 2015 Jul 13 & 14, 2015 Jul 27 & 28, 2015 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 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 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 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 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 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 Nov 21 & 22, 2017 Dec 4 & 5, 2017 Dec 18 & 19, 2017 Jan 2 & 3, 2018 Jan 16 & 17, 2018 mg/L TPSWC-1B TPSWC-2B TPSWC-3B MDC Chapter 24 Standard (500 mg/L, waste shall not increase natural background more than 10 percent)
DERM Class I Permit Required Monitoring in L-31E Canal Summary of Chloride Results June 2015 to January 17, 2018
L-31E Canal May 12, 2017 Physical Parameter Surface Water Quality Survey Monitoring sites (20 sites)
3.65 3.65 19.21 4.37 10.65 23.41 0.00 5.00 10.00 15.00 20.00 25.00 0 to 1 ft.
1.01 to 7.99 ft.
8 to 9.25 ft.
Salinity (PSU)
Depth Below Surface (ft.)
Min Max L-31E Canal Water Column Physical Parameter Survey Salinity Result Summary, May 12, 2017
0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 Jun/Jul 2010 Sep-10 Dec-10 Mar-11 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 pCi/L TPSWC-1B TPSWC-1T TPSWC-2B TPSWC-2T TPSWC-3B TPSWC-3T L-31E Canal Uprate Monitoring Tritium Results 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) 8 182 60.1 10.3 154 57.2 0
20 40 60 80 100 120 140 160 180 200 Min Max Average pCi/L 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
0 5
10 15 20 25 30 Salinity(PSU)
L31ECanalAverageDailySalinityattheBottom August30,2010toJuly16,2018 TPSWC1BAvgDailySalinity(PSU)
TPSWC2BAvgDailySalinity(PSU)
TPSWC3BAvgDailySalinity(PSU)
0 5
10 15 20 25 30 PSU L31ECanalAverageDailySalinityProfiles January1toJuly16,2018 TPSWC1TAvgDailySalinity(PSU)
TPSWC1BAvgDailySalinity(PSU)
TPSWC2TAvgDailySalinity(PSU)
TPSWC2BAvgDailySalinity(PSU)
TPSWC3TAvgDailySalinity(PSU)
TPSWC3BAvgDailySalinity(PSU)
Water Elevation (ft NGVD)
Model Lands Groundwater Control Elevations Current Water Management 0.5 ft 1.0 ft 1.5 ft 2.0 ft 2.5 ft 3.0 ft 3.5 ft Mean Sea Level FPL Everglades Mitigation Bank L-31E Culvert Weir Operations Existing S-20 Operations for Flood Control, Salt Intrusion Control FPL-EMB culvert operations, per Special Condition 15(d) of FDEP Permit 0193232-001, Mod 055 (June 25, 2013):
- 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 water level invert setting of the S-20 structure.
- During the dry season (October -
April), they will be set at 0.1 feet lower than the S-20 control elevation setting.
Local Wetland Ground Elevation (1.8 ft NGVD at TPGW-4, close to both S-20 and EMB culverts)
Water Levels that Support Environmental Services Optimum S-20 Headwater Elevation (per C&SF Master Manual)
31-Aug-10 30-Sep-10 31-Oct-10 30-Nov-10 31-Dec-10 31-Jan-11 28-Feb-11 31-Mar-11 30-Apr-11 31-May-11 30-Jun-11 31-Jul-11 31-Aug-11 30-Sep-11 31-Oct-11 30-Nov-11 31-Dec-11 31-Jan-12 29-Feb-12 31-Mar-12 30-Apr-12 31-May-12 30-Jun-12 31-Jul-12 31-Aug-12 30-Sep-12 31-Oct-12 30-Nov-12 31-Dec-12 31-Jan-13 28-Feb-13 31-Mar-13 30-Apr-13 31-May-13 30-Jun-13 31-Jul-13 31-Aug-13 30-Sep-13 31-Oct-13 30-Nov-13 31-Dec-13 31-Jan-14 28-Feb-14 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 TPGW-4S, August 31, 2010 - February 2, 2015 Water Level (ft NGVD29)
Nearby Wetland Ground Elevation (1.8 ft NGVD)
Water Elevation (ft NGVD)
Model Lands Groundwater Stages Existing Conditions vs. Healthy Ecology 0.5 ft 1.0 ft 1.5 ft 2.0 ft 2.5 ft 3.0 ft Existing S-20 Operations FPL L-31E Culvert Weir Operations Mean Sea Level 3.5 ft 2011: <5 months 2012: <8 months 2013: <4 months 2014: <5 months Healthy Sawgrass Prairie:
8-10 months Hydroperiod#
- Wetzel 2001. Plant Community Parameter Estimates and Documentation for the Across Trophic Level System Simulation (ATLSS). Data Report Prepared for the ATLSS Project Team, University of Tennessee-Knoxville, 59Pp.
I-4 I-3 EEL2 EEL1 L31E-F L31E-E L31E-D 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 Rockmining Lands and Associated Mitigation Model Lands Surface Water Specific Conductance L-31E borrow canal and Model Lands South canal April 2018 Depth SpCond (u/s)
T (0.179m) 5934.9 EEL2 Depth SpCond (u/s)
T (0.1m) 5408 EEL1 0
0.4 0.8 1.2 1.6 0.2 Miles
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