Where Will It Go - Successfully Siting and Permitting the Remote Georgetown Wet Weather Treatment Station in a Dense Urban Area

摘要

Management of wet-weather flows is challenging utilities across the globe. Environmental, regulatory, and public pressures are requiring utilities to embark on programs to plan for and design facilities to convey, store, and treat the large volume of wet-weather flows to reduce the frequency of untreated discharges to receiving waterbodies. Many times, remote storage or treatment facilities located upstream of the wastewater treatment plant are the most cost-effective and feasible options because they reduce the need to increase capacity of conveyance facilities and the wastewater treatment plant to handle the additional flow. Locating these remote facilities is challenging for several reasons, the primary reason being that these remote facilities tend to be most cost-effective when located near the combined sewer overflow (CSO) outfalls where wet-weather flows need to be intercepted to reduce the frequency of untreated discharges. However, in many cases, these areas are typically fully developed, highly dense urban areas with limited availability of real estate that is expensive and can include significant demolition and business displacement. These areas also include constructability risks because of the close proximity to receiving waterbodies, including poor soils, liquefaction risk, and high groundwater. Permitting of these facilities is also challenging due to the existing land uses, setback limitations, height restrictions, shoreline implications, and noise regulations. In addition to the challenges associated with siting and permitting of these facilities, which require coordination with third parties for negotiations and approvals, this project required a compressed schedule to meet regulatory requirements associated with the Consent Decree deadlines. Siting and permitting remote facilities are seldom discussed but equally as important as the treatment technologies and design of the facilities themselves. This paper presents the collaborative approach implemented by the King County Wastewater Treatment Division to site and permit the Georgetown Wet Weather Treatment Station (GWWTS) in a dense urban area. The GWWTS collectively includes the wet-weather treatment station, influent and effluent conveyance pipelines, and an outfall structure in the Lower Duwamish Waterway.