sweeney

Final Environmental Assessment – Sweeney WTP Expansion Proposed Project Description 1. Proposed Project Description 1.1 Introduction The City of Wilmington’s water treatment and distribution system is entirely owned and operated by the City. The City operates the 27.5 million gallon per day (mgd) Sweeney Water Treatment Plant (WTP), serving a population of approximately 121,000 (as indicated by the North Carolina Division of Environmental Health [DEH], Public Water Supply) within the limits of the City’s distribution system as well as a variety of commercial, governmental, and industrial customers. Bulk customers include the Wilmington International Airport Authority, University of North Carolina at Wilmington, and New Hanover Regional Medical Center. The Sweeney WTP consists of two parallel plants that are referred to as the South Plant (1943 plant) and the North Plant (1998 expansion). The Sweeney WTP treats surface water from the Cape Fear River either pumped from its own intake or purchased from the Lower Cape Fear Water and Sewer Authority (LCFWASA). The City commissioned the 2005 Water System Master Plan from ARCADIS in order to develop 20 and 50-year water demand projections for the existing and potential service areas and evaluate needed water system improvements. The Master Plan includes recommendations for infrastructure planning for the City’s water supply, water treatment, and water distribution facilities through 2025 and long-term planning through a 50-year planning horizon. This study found that additional water treatment capacity will be needed by 2010 and recommended that the City evaluate alternatives for expanding the Sweeney WTP as soon as possible. It also recommended the City continue to place priority on implementing aquifer storage recovery (ASR) projects and carefully allocate remaining water treatment capacity until the Sweeney WTP can be expanded. Water is a regional resource, and local governments must begin working together in order to ensure that adequate water quality and supply are available for years to come. The City of Wilmington has had discussions with New Hanover County, the Town of Carolina Beach, and the Town of Wrightsville Beach concerning their future water supply needs. The City has presently secured verbal agreements with Carolina Beach and Wrightsville Beach to provide both of these communities a maximum of 1 mgd each. The City also plans to serve some areas of New Hanover County south of the City limits. Expansion of the City’s facilities will benefit the area by providing a reliable source of high quality drinking water to citizens and businesses. 1.2 Proposed Project Scope This project consists of a State Environmental Policy Act (SEPA) Environmental Assessment (EA) to allow the City of Wilmington to apply for approval to expand the Sweeney WTP from a treatment capacity of 27.5 mgd to a final capacity of 44 mgd. The Sweeney WTP will be designed for a treatment capacity of 44 mgd, but will have a permitted capacity of 35 mgd initially, pending demonstration testing to re-rate the filters. Pursuant to SEPA, any proposed WTP capacity increase greater than 1 mgd requires an EA to be ARCADIS Project No. NC706001.0002 1-1 Final Environmental Assessment – Sweeney WTP Expansion Proposed Project Description completed and a Finding of No Significant Impact (FONSI) to be granted before the DEH will issue permits and approvals for this project. The City of Wilmington requests approval for this expansion in order to meet the projected demands of the existing service area and provide water to neighboring communities where water resources are limited. The 2005 Master Plan showed that additional water treatment capacity will be needed by 2010 in order to meet the needs of existing City of Wilmington customers. These demands have been updated for this EA, and current projections show that additional water treatment capacity will be needed by 2011. Additionally, neighboring communities have requested water from the City, including Carolina Beach, Wrightsville Beach, and Monterrey Heights. These neighboring systems obtain their water supply from wells, which are experiencing increasing chloride concentrations due to saltwater intrusion. The City’s raw water intake on the Cape Fear River is protected from saltwater intrusion by Lock and Dam No. 1. The City will be unable to meet these additional needs without the proposed project. This EA includes evaluations of the general environmental issues related to the project as well as the impacts of specific infrastructure components of the proposed WTP. This EA will document the need for the project, provide an analysis of the project alternatives, and describe the existing environment, predicted environmental impacts, and mitigative measures. 1.3 Project Area Description The proposed service area for this project encompasses 71 square miles, including the City of Wilmington’s existing water system service area, the existing water service areas for Carolina and Wrightsville Beaches, un-served areas south of the City including the Cameron Property, and one area south of the City currently served by New Hanover County (Figure 1-1). The project area includes the service area and a 25-mile long, 50-foot wide corridor along the existing raw water transmission main easements between the Sweeney WTP and the raw water intake at the City’s Kings Bluff Pump Station on the Cape Fear River. The project area is illustrated in Figure 1-2. ARCADIS Project No. NC706001.0002 1-2 Raw Water Transmission Easement NEW HANOVER COUNTY Sweeney Water Treatment Plant Wilmington Wrightsville Beach ATLANTIC OCEAN Cape F e ear Riv r BRUNSWICK COUNTY Carolina Beach 1 inch equals 2 miles 0 0.5 1 2 3 4 Miles Legend City of Wilmington Existing Water System Service Area Carolina Beach Existing Water System Service Area Wrightsville Beach Existing Water System Service Area Proposed Future Service Area Wilmington Corporate Limits County Boundary Streams and Lakes Figure 1-1: Service Area City of Wilmington Sweeney Water Treatment Plant Expansion Project BLADEN COUNTY Pump Station and Intake Sites PENDER COUNTY Raw Water Transmission Easement COLUMBUS COUNTY NEW HANOVER COUNTY Sweeney Water Treatment Plant Wilmington Wrightsville Beach BRUNSWICK COUNTY ATLANTIC OCEAN Legend City of Wilmington Existing Water System Service Area Carolina Beach Existing Water System Service Area Proposed Future Service Area County Boundary Wrightsville Beach Existing Water System Service Area RIVER CAPE FEAR Raw Water Transmission Easement Carolina Beach Wilmington Corporate Boundary Streams and Lakes 2.5 1.25 0 1 inch equals 3 miles 2.5 5 7.5 Miles Figure 1-2: Project Location Map City of Wilmington Sweeney Water Treatment Plant Expansion Project