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Title: Modified Water Deliveries to Everglades National Park Project : Removal of Unconstructed Conveyance and Seepage Control Features
Authors: United States. Army. Corps of Engineers. Jacksonville District
Keywords: Everglades (Fla.)
Publisher: United States. Army. Corps of Engineers. Jacksonville District.
Abstract: The U.S. Army Corps of Engineers, Jacksonville District (Corps), has conducted an environmental assessment in accordance with the National Environmental Policy Act of 1969, as amended. The Corps assessed the effects of the following actions in the Modified Water Deliveries to Everglades National Park (MWD) Project: Removal of Unconstructed Conveyance and Seepage Control Features Environmental Assessment (EA), dated February 2017, and the Corps technical analysis dated September 2015 (Appendix A) for the MWD Project in Miami-Dade County, Florida. The proposed action consists of the following: a.) Removal of authorized conveyance and seepage control features (CSCF) originally included in the MWD Project CSCF components that have not been constructed. Specifically, the components to be removed from the authorized project and associated Project Cooperation Agreement (PCA) include: (1) gated culvert structures S-345A, B, and C through the L-67A; (2) gated concrete headwall structures S-349A, B, and C in the L-67A Borrow Canal; and (3) degradation of the remaining 5.5 miles of the L-67 Extension. b.) Amending the PCA between the Corps and the non-federal sponsor, the South Florida Water Management District (SFWMD), to revise the term "project" to eliminate the unconstructed CSCF components and incorporate the 2012 design refinement for the 8.5 SMA. The current PCA, which identifies cost share and construction, operation, and maintenance responsibilities, defines the term "project" by referring to the 1992 MWD General Design Memorandum and Environmental Impact Statement (GDM/EIS), 2000 8.5 Square Mile Area (SMA) General Reevaluation Report and Environmental Impact Statement (GRR/EIS), and 2008 Tamiami Trail Modifications (TTM) Limited Reevaluation Report and Environmental Assessment (LRR/EA). c.) Completion of a series of operational tests (MWD Increment 1, MWD Increment 1.1/1.2, MWD Increment 2, and development of a Combined Operational Plan (COP) for the constructed features of the MWD Project and Canal 111 South Dade Project features. At this time, COP is anticipated to be implemented by 2019. It must be noted, however, that operational testing under the MWD Project increments may reveal the need for additional construction to address adverse effects associated with increased flow into Everglades National Park (ENP) associated with the MWD Project. d.) Development of an Operations, Maintenance, Repair, Rehabilitation, and Replacement (OMRR&R) Manual before the features can be transferred to SFWMD for operation. The OMRR&R Manual will be developed based on the results of the incremental testing and the comprehensive water control plan update (i.e. COP). In addition to the No Action Alternative, two alternatives were evaluated, including the proposed action. While the proposed action will not achieve the benefits to Water Conservation Area 3B as originally envisioned in the 1992 MWD GDM/EIS, the Recommended Plan is consistent with MWD Project design refinements documented within the 2000 8.5 SMA GRR/EIS, the 2008 TTM LRR/EA, and the 2012 8.5 SMA EA. In addition, as outlined in Appendix A, and in coordination with the Department of the Interior and SFWMD, the Corps 2015 technical analysis determined that the previously constructed MWD Project features, the MWD Project features currently under construction, C-358 and S-357N, along with the acquisition of remaining real estate interests and completion of a project water control plan (i.e. COP), will achieve the statutory charge to improve water deliveries into ENP and, to the extent practicable, restore the natural hydrological conditions within ENP. Given that the authority under which the MWD Project was developed was focused on delivery of water to ENP and improvement of the hydrology, to the extent practicable within ENP, the design changes and additional costs to make the necessary changes to the MWD Project to provide the benefits envisioned in the 1992 MWD GDM/EIS outside ENP would be difficult to justify under this authority. Although located within ENP, the 2008 TTM LRR/EA concluded that degradation of the remaining L-67 Extension may cause stages to exceed the MWD Project L-29 Borrow Canal maximum operating limit and compromise the condition of the Tamiami Trail roadway. Further improvements to water delivery volumes into ENP by up to 92%, compared to pre-MWD conditions described in the LRR, and improved hydrologic conditions within ENP can be expected upon completion of COP. Applicable real estate acquisitions must be completed to support the MWD increments operational tests needed to inform COP.
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