HERBERT HOOVER DIKE DAM SAFETY MODIFICATION STUDY GLADES, HENDRY, MARTIN, OKEECHOBEE AND PALM BEACH COUNTIES, FLORIDA DRAFT ENVIRONMENTAL IMPACT STATEMENT December 2015 Executive Summary Cover Sheet DRAFT ENVIRONMENTAL IMPACT STATEMENT HERBERT HOOVER DIKE DAM SAFETY MODIFICATION STUDY Glades, Hendry, Martin, Okeechobee, and Palm Beach Counties, FL Lead Agency: Department of Army U.S. Army Corps of Engineers, Jacksonville District Abstract: The purpose of the Herbert Hoover Dike (HHD) Dam Safety Modification Study (DSMS) is to identify and recommend a cost effective alternative risk management plan (RMP) that supports the expeditious reduction of risk at HHD. While the primary purpose of the remediation of HHD is to ensure public safety, objectives of the project also include lowering the probability of experiencing a breach and incurring impacts on ecological, cultural, and aesthetic resources and the Everglades resulting from a breach. Species and habitats directly on the dike and within the path of the water due to a breach would be negatively impacted, and snail kite critical habitat could be negatively impacted due to lower lake levels. Further, if a breach were to occur along the southern perimeter of HHD, flooding would occur within the Everglades Agricultural Area (EAA) and further south, through the Water Conservation Areas (WCAs) and eventually to Everglades National Park. There are many state and federally protected species within south Florida that would be negatively impacted due to a loss of habitat from flooding resulting from a breach of HHD. The comparison of the final array of Alternatives has resulted in the identification of the economically, environmentally, and socially efficient alternative as the plan being recommended to reduce the overall risks attributed to a breach associated with the Herbert Hoover Dike. Alternative 3 has been identified as the preferred alternative/tentatively selected plan (TSP). The TSP consists of cost-effective structural measures that work in unison to reduce the likelihood of a breach at HHD and achieves the primary objective of protecting public safety. The TSP includes construction of risk reduction measures around the southern half of HHD and limited areas in the northwest sides of the dam, greatly reducing the potential for breach-related damages to the nationally significant agricultural industry in the Everglades Agricultural Area, and the nationally and internationally significant Everglades ecosystem. The probability of experiencing a breach and incurring substantial impacts on ecological, cultural, and aesthetic resources would be greatly reduced with the implementation of the TSP. Adverse effects associated with implementing the TSP are expected to be minimal to moderate. Many effects, such as impacts to recreation and noise levels would be temporary during construction activities. Send your comments by: For further information on this statement, please contact: February 23, 2016 Stacie Auvenshine U.S. Army Corps of Engineers P.O. Box 4970 Jacksonville, FL 32232-0019 Telephone: 904-232-1682 E-mail: [email protected] HHD Dam Safety Modification Study Draft EIS December 2015 ii Executive Summary EXECUTIVE SUMMARY Background Authorization: The HHD is a component of the Central and Southern Florida (C&SF) Project for Flood Control and Other Purposes. It is generally understood that the birth of the C&SF Project began with the Flood Control Act of 1948; however, Federal participation in local flood control efforts in the Lake Okeechobee area started much earlier in response to the disastrous hurricanes of 1926 and 1928. The Rivers and Harbors Act of 1930 authorized the construction of levees for protection from storm surge- induced flooding along the north and south shores of Lake Okeechobee. The 1948 Act created the C&SF Project and included authorization for enlargement of the existing levees and construction of additional levees along the northeast and northwest shores. The Flood Control Act of 1960 authorized the name of all levees around the shore of Lake Okeechobee to be “Herbert Hoover Dike”, in honor of the former President and his role in implementing levee construction. Purpose: The Herbert Hoover Dike (HHD), surrounding Lake Okeechobee, is currently recognized as requiring urgent repairs to minimize risks to public safety and to provide a tolerable level of economic, societal and environmental security in the region. The objective of the HHD Dam Safety Modification Study (DSMS) and Draft Environmental Impact Statement (EIS) is to identify and recommend a cost effective alternative risk management plan (RMP) that supports the expeditious reduction of risk from a breach of HHD. While the primary purpose of the remediation of HHD is to reduce risk to public safety, objectives of the project also include lowering the probability of experiencing a breach and incurring impacts on ecological, cultural and aesthetic resources and the everglades resulting from a breach. If a breach were to occur, both federally and state listed species, and habitats directly on the dike and within the path of the water due to a breach would be negatively impacted. Snail kite critical habitat in the southern portion of HHD could be negatively impacted due to lower lake levels. Further, if a breach were to occur along the southern perimeter of HHD, flooding would occur within the EAA and further south, through the Water Conservation Areas (WCAs) and eventually to Everglades National Park, negatively impacting species due to loss of foraging and nesting habitat. If a breach were to occur along the northern perimeter of HHD, flooding would be more localized due to the topography of the area; however, minimal effects would occur. Alternatives The Corps analyzed 11 alternatives for the HHD Dam Safety Modification Study (see Section 2 for more detailed description and figures). This Draft Environmental Impact Statement (EIS) analyzes the environmental effects of (1)the No-Action Alternative; and (2) four alternatives with various cutoff wall locations and depths, and downstream armoring and floodwalls in select areas of low crest elevation (one of which has been selected as the TSP). In accordance with ER-1105-100, the socioeconomic impacts of the alternatives must be considered in plan formulation and evaluation. Typically, economic impacts are measured by National Economic Development (NED). In the case of the HHD DSMS, NED impacts are measured as reduced economic risk. Changes in economic risk are documented in Section 4 of the main report. However, Regional Economic Development (RED) and Other Social Effects (OSE) should also be considered. RED considers regional economics, such as benefits of employment during construction or recreational features gained or lost, rather than on a national level. OSE include environmental justice, HHD Dam Safety Modification Study Draft EIS December 2015 iii Executive Summary prime and unique farmlands, protection of children, health and safety, and recreation. The comparison of the final array has resulted in the identification of the economically, environmentally, and socially efficient alternative as the plan being recommended to reduce the overall risks attributed to a breach associated with Herbert Hoover Dike. Alternative 3 has been identified as the TSP. The TSP is a cost- effective plan consisting of structural measures that work in unison to reduce risk, achieving the primary objective of protecting public safety. The TSP includes constructing risk reduction measures along most of the southern half of HHD and in limited areas of the northwestern perimeter of HHD, greatly reducing the potential for breach-related damages to the communities surrounding HHD, the nationally significant agricultural industry in the Everglades Agricultural Area, and the nationally and internationally significant Everglades ecosystem. Description of the TSP: A cutoff wall was determined to be the least costly, technically acceptable risk reduction measure for remediation of the HHD embankment in areas that have been identified as high risk due to internal erosion failure modes (erosion of the internal structure of the embankment due to seepage forces). This alternative includes a cutoff wall around the southern perimeter of HHD, extending the previously constructed cutoff wall from the end of Belle Glade to just north of Moore Haven, terminating at the intersection of HHD and interceptor Levee 41. The TSP also includes cutoff wall along the northwest perimeter of HHD in the vicinity of Lake Port. Lastly, the TSP includes isolated areas of downstream armoring on the abutments of SR 78 Bridge over Harney Pond Canal and floodwall around S71 and S72 at the northern terminus of HHD on Harney Pond Canal and Indian Prairie Canal, respectively. These areas were identified as low points in the crest of HHD that were considered excessively vulnerable to overtopping under combined loading events of elevated lake stages and tropical cyclone impact. Additional coordination is needed with the non-Federal sponsor (Florida Department of Transportation) to identify the need to raise the SR78 Bridges over Harney Pond, Indian Prairie, and the Kissimmee River to match adjacent embankment crest elevations. This work is recommended to be completed as the infrastructure reaches the end of the design surface life or becomes scheduled for replacement for other reasons. Due to the remote combination of loading conditions that could cause overtopping at these locations, only