Seeley County Water District Wastewater Treatment Plant Improvements Project

The Seeley County Water District owns and operates the Wastewater Treatment Plant (WWTP). The District serves the community of Seeley, California, providing water and wastewater services within a 2.26-square-mile service area. Collected wastewater is treated at the District's WWTP. The existing WWTP consists of a septage receiving facility, an influent lift station with coarse screen, primary treatment consisting of an aerated pond treatment system that includes pre-aeration and aeration ponds, effluent pumping, secondary treatment that consists of pressure sand filters, and an ultraviolet (UV) disinfection system. The existing WWTP is designed for a treatment capacity of 0.25 million gallons per day (MGD) with current average annual daily flows of 0.11 MGD. The existing WWTP is in good condition but is incapable of handling the more concentrated wastewater stream that has been created over the years from conservation measures that lower water consumption throughout the service area. This has led to failure to comply with effluent requirements and notices of noncompliance including an Administrative Civil Liability Complaint with Mandatory Minimum Penalties (MMPs) for effluent violations and a Time Schedule Order. The goal of the project is to improve treatment performance to conform to resolve recent effluent violations and allow the WWTP to adjust operations to accommodate future changes in effluent limits. The proposed upgrades of the WWTP will result in a treated flow capacity of 0.15 MGD, lower than the facility’s current design capacity and permitted effluent flow limit but still capable of accommodating increases in flow associated with future growth in the service area. Project upgrades primarily consist of upgrading the WWTP’s secondary treatment system from a pressure sand filter system to a membrane bioreactor (MBR) system as well as several on-site improvements.