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Title: Environmental Assessment and Finding of No Significant Impact: Planned Temporary Deviation to Life Constraints on Water Conservation Area 3B, Site 71 for Relief of High Water Levels Within Water Conservation Area 3A: Broward and Miami-Dade Counties, Florida
Authors: United States. Army. Corps of Engineers. Jacksonville District.
Keywords: Everglades (Fla.)
Flood control
Environmental protection
Publisher: United States. Army. Corps of Engineers. Jacksonville District.
Abstract: In order to provide relief from high water stages within WCA 3A, the Corps is initiating a planned temporary deviation from Phase 2 of the DECOMP Physical Model operational strategy to raise the stage constraint at gages SRS-1 and/or Site 71 from 8.5 ft. NGVD to 8.7 ft., NGVD from the beginning of this deviation through September 15, 2018, and then up to 9.0 ft., NGVD from September 16, 2018 through November 30, 2018 allowing approximately 18,000 acre-feet per month discharges out of WCA 3A, based on 300 cubic feet per second (cfs) flow rate through S152. Discharges from each of the outflows structures (S-31, S-355A, S-355B, WCA 3B temporary outflow pumps placed at S-355B, S-335 (by way of seepage into the L-30 Canal from WCA 3B)) for WCA 3B will be regulated to help avoid exceeding the deviation constraint limit measured at Site 71 or the SRS-1. If the WCA 3A, 3-gage average falls below WCA 3A, Increment 2 Action Line prior to November 30, 2018, the WCA 3B outflow structures will continue to be utilized until the stage measured at the Site 71 or SRS-1 recedes below 8.5 ft., NGVD. The intent of this operation is to transition the stage at Site 71 or SRS-1 from the deviation constraint limit to 8.5 ft., NGVD prior to WCA 3A stage receding below Zone A of the WCA 3A Regulation Schedule. Outflow structures’ discharges will be subject to their respective downstream constraints. The SFWMD is also currently installing four 30-inch pumps (with a total installed capacity of approximately 200 cfs) along the L-29 levee to further facilitate the movement of water from WCA 3B to the L-29 Canal. Reference Appendix B for additional information regarding the temporary installation of pumps. The planned temporary deviation will be needed until the WCA 3A stage, as measured by the average of Site 63, Site 64 and Site 65 gages (3-gage average) falls below Zone A of the WCA 3A Regulation Schedule, or November 30, 2018 whichever occurs first. The planned temporary deviation will extend no later than the duration of the Florida Department of Environmental Protection (FDEP) Emergency Final Order (EFO). The FDEP issued an EFO in response to high rainfall and flooding in the South Florida Region, OGC No.: 18-1066, on June 20, 2018 (Appendix B). The EFO states that the Corps and SFWMD are hereby authorized to make temporary operational changes in order to minimize detrimental impacts to the environment, to the public, to adjacent properties, and to downstream receiving water. The Proposed Action is expected to increase water stages within WCA 3B temporarily; however water elevations due to the deviation operations will not exceed those historically experienced as a result of periodic rain events. The Proposed Action is expected to mitigate for severe ecologic and economic losses that could result from prolonged high water levels. Loss of natural resources directly affects fisheries and fishing, hunting, and ecotourism. The Proposed Action is the third planned temporary deviation conducted in 2018 to alleviate high water conditions within WCA 3A.
Description: Environmental Assessment / Finding of No Significant Impact
Rights: Approved for Public Release; Distribution is Unlimited
Size: 60 pages / 1.679 Mb
Types of Materials: PDF
Appears in Collections:Environmental Documents

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