Environmental Declaration WPCP 20240409

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2. Project Description Recent WPCP Upgrades Between 2011 and 2015, the WPCP constructed a major treatment plant rehabilitation to address aging infrastructure and implement other improvements, including: • Replaced the headworks, including a new screenings removal facility. Constructed a new grit facility to increase wastewater treatment efficiency. a Rehabilitated two (2) primary clarifiers and added a third primary clarifier to enhance wet weather treatment capacity. a Constructed a new Fixed Film Reactor and associated biofilter for odor control. ■ Constructed a new three -million -gallon lined storage lagoon for storage of wet weather flows. a Upgraded the electrical system and constructed a new administrative and laboratory building. Additional upgrades and investments made in the last decade to increase energy efficiency and plant performance: Installation of a new high efficiency 'turbo blower' to provide air to the activated sludge aeration basin, significantly reducing energy consumption and operational performance. Installation of a 1-megawatt solar array in a repurposed portion of the WPCP's sludge drying beds to reduce energy consumption and help meet San Leandro's Climate Action Plan objectives. 2.3. Project Description The Proposed Project involves installation of a modular nitrification system to convert ammonia, from existing secondary treated wastewater, to nitrate, and converting a 6.9-acre wastewater retention pond to multi -benefit treatment wetland. Nitrified effluent shall be polished in the treatment wetland for the removal of nutrients and other pollutants prior to discharge to San Francisco Bay via an existing discharge pipe. The design approach utilizes a hybrid system that includes both vegetated subsurface flow wetlands (terraced bioreactors) along the basin perimeter slopes, combined with shallow free water surface (FWS) wetland areas. This will serve to enhance overall nitrogen removal rates of the system, while creating wet meadow habitat along the basin perimeter and along potential interior dike features. The proposed treatment wetland will receive a portion of the effluent from the WPCP, not to exceed 0.95 mgd, that has passed through an engineered nitrification system with an expected nitrification efficiency of 75-90%. Expected influent NO3-N concentrations range between 30-36 milligrams per liter (mg/L). Polished wastewater will discharge directly to San Francisco Bay at the existing outfall located at the western edge of the existing basin, consistent with the existing NPDES permit for the Proposed Facility. Figure 2-9 illustrates conceptual -scale features of the Proposed Project, and Figures 2-10 through 2-11 represent conceptual views of the basin and the proposed features. San Leandro Treatment Wetland IS/MND February 2024