FINDING OF NO SIGNIFICANT IMPACT JORDAN LAKE AERATION SYSTEM FOR THE CARY/APEX WATER TREATMENT FACILITY CHATHAM COUNTY, NORTH CAROLINA September 2013 Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 Finding of No Significant Impact Jordan Lake Aeration System For the Cary/Apex Water Treatment Facility Chatham County, North Carolina September 2013 Table of Contents Subject: 1.0 Introduction............................................................................................................... 1 2.0 Proposed Action.........................................................................................................1 3.0 Changes to Environmental Assessment..................................................................... 2 4.0 Alternatives Considered.............................................................................................3 5.0 Public and Agency Coordination............................................................................... 4 6.0 Impacts of the Proposed Action................................................................................. 5 7.0 Finding of No Significant Impact.............................................................................. 6 Tables: Table 1. Environmental Impacts Comparison of Proposed and No Action Alternative Appendices: Appendix A – Exhibits Exhibit 1. General Project Location Exhibit 2. Proposed Lake Aeration System Appendix B – Responses to EA Comments Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 1.0 INTRODUCTION The National Environmental Policy Act of 1969, as amended (NEPA), requires consideration of the environmental impacts for major federal actions. The proposed action and the environmental impacts of the proposed action were addressed in the Environmental Assessment for Direct Impacts of the Proposed Jordan Lake Aeration System for the Cary/Apex Water Treatment Facility, Chatham County, North Carolina (EA), dated December 2012. The EA was coordinated with various regulatory agencies and the public and comment letters were received. This Finding of No Significant Impact (FONSI) documents the environmental considerations, the decision that no significant impacts would occur if the proposal is implemented, and explains the rationale used in selecting the alternative proposed for implementation. This FONSI has been prepared pursuant to NEPA in accordance with the Council on Environmental Quality (CEQ) regulations as contained in 40 CFR Parts 1500 to 1508, which directs federal agencies on how to implement the provisions of NEPA. 2.0 PROPOSED ACTION The Town of Cary, in partnership with the Town of Apex, proposes to construct, operate, and maintain a lake aeration system at B. Everett Jordan Reservoir (Jordan Lake) in the vicinity of the raw water intakes and Raw Water Pumping Station (RWPS) for the Cary/Apex Water Treatment Facility (CAWTF) (Exhibit 1). The purpose of the proposed lake aeration system is to assist with improving lake water quality in the vicinity of the Towns’ water supply intakes in Jordan Lake. The aeration system would reduce dissolved manganese and iron concentrations, likely reduce the proliferation of blue green algae blooms in the vicinity of the intake and associated taste and odor issues, and improve the overall Lake quality in the area in which the intakes are located. Providing better Lake water would reduce energy demands, chemical treatment requirements and resulting waste residuals generated at the CAWTF. In addition, it would allow the Towns to continue to maintain their high levels of service in providing a reliable and safe drinking water to customers while holding down costs of treating the Jordan Lake supply and provide more flexibility to treat water during droughts. The construction, operation, and maintenance of a lake aeration system in Jordan Lake are consistent with the congressionally authorized use of the Reservoir for water supply storage. Other authorized purposes of the Reservoir include recreation, flood control, and fish and wildlife conservation. The proposed aeration system is a mechanical aeration system that would destratify a portion of the Lake by slowly circulating oxygen rich water from the surface of the lake to the oxygen poor lake depths resulting in better circulation in the lake for overall improved water quality. The proposed system would consist of two floating platforms located approximately 100 feet apart (Exhibit 2) and approximately 2,500 feet from the existing RWPS. Each platform would contain two 15-ft diameter aeration units located approximately 12-ft apart from each other. Each aerator would be equipped with a 7.5 HP electric motor driven by a variable frequency drive. Other components of the aeration system would include a connecting walkway between the two aeration units, aeration pumps, a standing platform, baffle curtains, anchoring cables, anchoring concrete blocks, and a power supply. 1 Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 Each aeration pair would be anchored to the Lake bottom with four to six anchoring cables which would be connected to concrete anchors on the Lake bottom. The floating platform therefore moves with the operating water level. Power would be supplied to the aeration system via the RWPS. Two construction options for the submersible cable include surface lay or burial in a trench. Survey and geotechnical borings would need to be conducted for the proposed route to determine Lake bottom conditions and identify any potential obstructions to the proposed cable route and installation method. A temporary assembly and launching area would be required to assemble the aeration systems and for launching the systems with a crane into the Lake. The estimated temporary assembly/launching area requirement is 100 ft x 100 ft. The marina located northeast of the existing CAWTF RWPS site is the proposed assembly/launching area. The marina was used previously for temporary launching of construction equipment in 2002 associated with raising the existing lower raw water intake unit. The Town of Cary has requested a total real estate easement of approximately 60,000 square feet (1.4 acres) from the USACE. Approximately 0.8 acres of the requested easement would include areas for the aeration units, the anchoring cables, the concrete anchors, the submersible electrical cable, and a buffer area for establishing a no-boating-or-recreational-activities area around the aeration units. The remaining 0.6 acres of easement area was requested for a maintenance corridor to access the submersible electrical cable. The estimated easement area for the submersible electrical cable is based on a 10-ft wide easement along the length of the cable and 2,500 ft distance between the RWPS and the aeration system location. The easement is not anticipated to require changes in land use surrounding the easement, removal of existing structures, or relocation or abandonment of existing utilities. 3.0 CHANGES TO ENVIRONMENTAL ASSESSMENT Section 3.3 Hypolimnetic Aeration via Oxygenation / Aeration, of the EA contained incorrect information concerning the effects of hypolimnetic aeration systems on blue-green algae growth. This section has been revised and corrected by updating the section’s final paragraph, and accompanying advantages/disadvantages table, to read as follows: Fish species present in Jordan Lake, as noted by North Carolina Wildlife Resources Commission (NCWRC) in its September 2011 scoping comments, are characterized as warm water species (Appendix B). In addition, Jordan Lake is considered a medium depth reservoir and does not have a significantly large hypolimnion. Further, the CAWTF intakes are located at various depths within the water column, making it more desirable to achieve water quality improvements across the water column than just within the hypolimnion. Finally, hypolimnetic aeration systems can indirectly impact blue-green algae production and taste and odors and do not fully address the purpose and need for the proposed Lake Aeration System. For these reasons, hypolimnetic aeration systems are not considered the appropriate technology for the project area. The advantages and disadvantages of this alternative are summarized as follows: Advantages Disadvantages Provides oxygen to the lower portion of the lake May have limited benefit in addressing reducing levels of dissolved iron and manganese, blue green algal growth and associated and other problem constituents in the hypolimnion taste and odor issues For cold water reservoirs, increases habitat for cold Generally better suited for deep water fisheries reservoirs with large hypolimnion but can result in nutrient reduction 2 Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 Bottom mounted technologies result in lower Generally, does not address water interference with boaters in comparison to floating quality concerns in the epilimnion but mixers. Aeration compressors and equipment are can result in nutrient reduction which mounted on the shore can impact algal productivity Does not fully address project purpose and need Section 3.4 Mechanical Aeration using Solar Bee Aeration System, of the EA contained incorrect information concerning flow patterns achieved by the Solar Bee Aeration System. This section has been revised and corrected by updating the section’s second and third paragraphs, as well as the accompanying advantages/disadvantages table, to read as follows, omitting incorrect flow pattern language: The system was not selected as the preferred alternative because it would require an estimated 20 floating aerators in the Lake, resulting in significantly higher navigational and recreational impacts in comparison to the proposed alternative. A summary of the advantages and disadvantages of the Solar Bee System follows. Advantages Disadvantages Mixes both the epilimnion and the hypolimnion. Requires 20 mixers to achieve needed aeration. Destratification of the Lake would reduce the Would cause significant interference to boat proliferation of algae blooms and improve traffic. overall Lake quality in the sub‐Lake in which the intakes are located. Lowest energy cost for active Lake quality improvements alternatives by use of solar energy. Aerators can be accessed for maintenance. 4.0 ALTERNATIVES CONSIDERED Several alternatives were considered in the EA, including several different alternative destratification systems and the No Action Alternative. Not installing a Lake Aeration System (No Action Alternative) would not address the poor water quality that historically occurs when the Lake stratifies and could result in increased taste and odor issues, high dissolved iron and manganese levels, increase in chemical consumption and residuals generation, reduced treatment efficiency, and increased risk of Safe Drinking Water Act (SDWA) violations at the CAWTF during periods of poor water quality. There are also concerns that recurring droughts, climate change, and future withdrawals from the Lake from other uses may increase variability of Lake operating levels and result in more frequent use of the existing lower intake which typically experiences poorer raw water quality conditions. Additional treatment systems would need to be implemented at the CAWTF to accommodate poor raw water quality. Lake management is a more cost-effective strategy than providing additional treatment systems at the CAWTF for accommodating poor raw water quality. It is therefore concluded that the No Action Alternative does not meet the project purpose and need. During the development of alternatives for the proposed action, several different alternative destratification systems other than the preferred downward circulation system were considered for the project. These options included artificial circulation via a bottom-mounted diffused aeration system, 3 Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 hypolimnetic aeration systems (including oxygen injection and air injection systems), and mechanical aeration systems including upward circulation systems. These alternatives were eliminated based on several factors, including environmental impacts, power requirements, maintenance costs, recreational/public impacts, secondary water quality concerns, and not fully addressing the project purpose and need. 5.0 PUBLIC AND AGENCY COORDINATION On February 6, 2013 the Environmental Assessment for Direct Impacts of the Proposed Jordan Lake Aeration System for the Cary/Apex Water Treatment Facility, Chatham County, North Carolina was mailed to federal and state agencies and the interested public for a 30-day review and comment period. The February 2013 EA mistakenly contained the word ‘DRAFT’, included on the cover page. The USACE NEPA guidance does not provide for Draft and Final Environmental Assessments comparable to Draft and Final Environmental Impact Statements. The February 2013 EA was distributed to federal and state agencies and the interested public. The EA as well as the comments received from the public have been considered in the decision to prepare this FONSI in accordance with NEPA requirements. Letters and memoranda on the EA were received from the following: Federal Agencies ▪ US Environmental Protection Agency, Region 4 ▪ US Fish & Wildlife Service ▪ National Resources Conservation Service State Agencies ▪ North Carolina Department of Administration State Clearing House ▪ North Carolina Department of Environment and Natural Resources - North Carolina Division of Water Resources, Public Water Supply Section - North Carolina Wildlife Resources Commission - North Carolina Office of Conservation, Planning, and Community Affairs, National Heritage Program - North Carolina Department of Transportation - North Carolina Division of Emergency Management, Floodplain Management Program - North Carolina Department of Cultural Resources – State Historic Preservation Office - North Carolina Division of Land Quality Local Communities ▪ None Elected Officials ▪ None Conservation Groups ▪ None Interested Businesses, Groups, and Individuals ▪ Aqua Sierra, Inc. ▪ Jim Frei, Stormwater Services Group, LLC ▪ SolarBee, GridBee, Medora Corporation ▪ BlueInGreen Comments received primarily concerned alternative aeration systems and boater safety. None of the comments received identified any reasonable alternatives or major substantive issues that were not already addressed in the EA. 4 Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 6.0 IMPACTS OF THE PROPOSED ACTION The proposed action is anticipated to have no to minimal impacts to the existing environment. It is anticipated that the proposed action would improve existing Lake water quality in the vicinity of the CAWTF intakes. A summary of project impacts is presented in Table 1. Table 1. Environmental Impacts Comparison of Proposed and No Action Alternative Resource Proposed Alternative No Action Geology None None Topography Minimal – would return grades to None existing contours Soils Minimal – most soils in the project None footprint were previously disturbed Floodplain Minimal – the proposed units float with None anchors on the Lake bottom Surface Hydrology Minimal – small footprint within None Jordan Lake Water Quality Creates better water quality Remains same Air Quality None – electric motors None Noise Minimal – the proposed motors are None smaller than the typical boat motor Cultural Resources None None Hazardous Waste Temporary – construction equipment Greater potential for increased would be required; however, it is quantities of chemicals needed at the expected that it would be maintained treatment plant for subsequent properly for leaks, fueling, etc. treatment of poor quality water Aesthetics Minimal overall small footprint None Vegetation Minimal – vegetation in the proposed None footprint is maintained Fish and Wildlife Minimal – Screens/velocities for the None aeration system are similar to those required for the intakes, potential for increasing warm water fish habitat by increasing D.O. in the water column. Endangered and None None Threatened Species Wetlands Minimal – potential for a small area of None fringe wetlands to be impacted due to laying of the electric line depending on Lake level Land Use None None Vehicular Traffic None None Recreation Minimal – Small footprint, None considerations for Lake user safety Water Supply and None None Conservation Energy Needs Minimal – small motors required use Greater as needs for subsequent less energy than most other options treatment increase Safety Minimal – Buoys, lighting, etc would None 5 Jordan Lake Aeration System for Cary / Apex WTF – FONSI September 2013 Resource Proposed Alternative No Action be used to ensure Lake user safety as well as protect the aeration units from damage Consideration of An additional 1.4 acres of easement None Property would be required from the Corps of Ownership Engineers. 7.0 FINDING OF NO SIGNIFICANT IMPACT I have reviewed the Environmental Assessment for Direct Impacts of the Proposed Jordan Lake Aeration System for the Cary/Apex Water Treatment Facility, Chatham County, North Carolina, the information provided by interested parties, and the information contained in this Finding of No Significant Impact, and I find that the proposed aeration system will not significantly affect the quality of the human or natural environment. Therefore, preparation of an Environmental Impact Statement pursuant to Section 102(2)(c) of the National Environmental Policy Act of 1969, as amended, is not required. Date: Steven A. Baker Colonel, U.S. Army District Commander 6