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3. Environmental Checklist San Leandro Treatment Wetland IS/MND 3-47 February 2024 the preparation of a SWPPP and the implementation of site-specific BMPs to mitigate erosion, sedimentation, and the release of hazardous materials. The SWPPP, prepared by a Qualified SWPPP Preparer and overseen by a Qualified SWPPP Practitioner, includes various elements such as good site management practices, erosion controls, sediment controls, and periodic site BMP inspection, maintenance, and repairs. These measures are designed to identify pollutant sources, reduce pollutants in stormwater discharges, and prevent non-stormwater discharges from reaching surface water or municipal drainage systems. Furthermore, the Project will operate in compliance with NPDES Permit No. CA0038881 and Title 22 requirements for irrigation of secondary treated effluent. In 2022, the RWQCB issued this NPDES Permit for the treatment wetland facility and discharges through the existing outfall to San Francisco Bay. This permit application was supported by a modeling study, site surveys, and subject to thorough review and public comment. The Proposed Project aims to nitrify secondary treated effluent from the WPCP and direct up to 0.95 mgd to seepage slopes along the edges of the existing basin featuring woodchip-containing crates planted with native vegetation designed to promote nitrogen removal and reduce nutrient loading to San Francisco Bay from the WPCP. Treated wastewater will be polished through the slopes and flow into the open water portion of the basin for additional removal of nutrients and organic pollutants. This novel approach will inform other nature-based solutions for nutrient management in the region and elsewhere. The subgrade of the internal basin will undergo a process of cement mixing and compaction to achieve a dry density of 90%, enhancing impermeability. An approximate volume of 11,000 cubic feet of clean fill will then be layered over the stabilized base. Additionally, an impermeable plastic liner will be installed to completely cover the base of the basin and extend up the side slopes beneath the woodchip bioreactor. This comprehensive sealing approach aims to eliminate pollution pathways to groundwater and soil, while also raising the surface elevation by approximately 6 feet. The basin is anticipated to reach a maximum depth of 18-24 inches when filled, resulting in minimal hydrostatic pressure on the liner and underlying basin. The polished effluent will be discharged into San Francisco Bay via the existing flow control structure located at the southwest corner of the 6.9- acre basin. The control structure will feature a new tide gate to prevent saltwater from entering the pond during extreme tides. Routine water quality testing will occur for reporting to the RWQCB in compliance with its NPDES permit. Water quality testing will be conducted in collaboration with regional researchers to assess the effectiveness of nutrient removal and other associated benefits. In conclusion, the implementation of the proposed advanced treatment facilities, SWPPP requirements, NPDES permit requirements, and design features outlined in the Project Description will effectively mitigate potential impacts on water quality, ensuring compliance with regulatory standards and minimizing environmental harm. Therefore, the Project's impact on surface water quality is expected to be less than significant. Impact Designation: Less than Significant Impact. b) Impact groundwater supplies: The subgrade of the internal basin will be cement stabilized, compacted, covered with one foot of fill, and coated with an impermeable liner to maximize treatment effectiveness and minimize surface water to groundwater interactions. Underlying groundwater