Environmental Declaration WPCP 20240409

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3. Environmental Checklist resources are not utilized for water supply and thus, the Proposed Project will not impede sustainable groundwater management of a groundwater basin. Impact Designation: No Impact c) Alter existing drainage patterns (i-iv): The Proposed Project is not anticipated to have a significant impact on stormwater volumes or flood risk potential. There will be no creation of new impervious surfaces or changes to existing drainage channels. The open water section of the Project will continue to capture rainfall within its barrier embankment during storm events. Additionally, the modular nitrification units will be installed on existing impervious surfaces and will not contribute to increased runoff or changes in drainage patterns. During the construction phase, a SWPPP will be implemented to control erosion, followed by the restoration of disturbed soils through planting and revegetation. Consequently, the Project is not expected to result in elevated erosion, sedimentation, or flooding either on -site or off -site, and it will not degrade water quality. Im act Desi nation: No Impact d) Flood -induced pollution: The Project site, situated along the Bay shoreline, faces potential vulnerability to seiche waves, although historical records indicate no occurrences within the Bay. Tsunami waves, however, have been observed, often originating from distant sources like Asia, Alaska, or South America. Despite this, as the Proposed Project does not include habitable structures, any damage from a tsunami would likely result in minimal impacts on people. In the event of levee overtopping along the southern perimeter of the basin, there may be discharge of co -mingled polished effluent and seawater, albeit with pollutants at minimal levels. Furthermore, the implementation of the Proposed Project will increase the basin's height by approximately six feet, with a new tide gate installed to mitigate against seawater intrusion and potential sea level rise. These measures aim to prevent adverse impacts on the surrounding topography and reduce the risk of loss, injury, or death in the event of a seiche and/or tsunami. Additionally, the relatively flat terrain of the surrounding area and the absence of nearby sources of mudflow mean that the Project would not be susceptible to mudflows. Impact Designation: Less than Significant Impact. e) Conflict with water quality plans: To ensure ongoing adherence to the San Francisco Bay Water Quality Control Plan (Basin Plan), the Proposed Project will operate in accordance with NPDES Permit No. CA0038881. The Proposed Project site is not subject to a groundwater management plan. imoact Designation_ No Impact Cumulative Impacts on Hydrology and Water Quality Simultaneous construction activities of the Proposed Project and other projects in the surrounding area may increase erosion of exposed soils and subsequent sedimentation, potentially impacting water quality in receiving waters. Additionally, accidental releases of fuels or hazardous materials during construction could affect water quality in stream channels or storm drains flowing into San Francisco Bay. However, measures are in place to manage all waters encountered or utilized during construction through the implementation of a construction -phase SWPPP, addressing dewatering, stormwater, and dust control. San Leandro Treatment Wetland IS/MND February 2024