San Timoteo Storm Drain
UltraSystems Environmental, Inc completed a Phase I Environmental Site Assessment; Technical Studies for Air Quality, Biological Resources and Noise Impacts; a Jurisdictional Delineation for Waters of the United States (WOUS) and Waters of the State (WOS), an Initial Study (IS); and a Mitigated Negative Declaration (MND) for an underground storm drain system. The system includes reinforced concrete pipe (RCP) placed in approximately four- to eight-feet wide and 10- to 22- feet deep trenches excavated within existing roadways. The underground storm drain system includes four segments with connector pipes and catch basins/inlet drains along a total length of approximately 3,650 feet. The new design discharge rate at the existing outlet at the terminus of system must accommodate discharge from 100-year storm event. At the recommendation of UltraSystems, extensive rip-rap or another dissipation structure would be placed at the existing outlet to reduce discharge flow velocity and potential downstream erosion of an un-named incised channel. UltraSystems identified mitigation measures to reduce noise and other potentially significant environmental impacts to less than significant levels, and completed jurisdictional delineations for federal and state wetlands and riparian habitats potentially impacted upstream and downstream of the system inlet and outlet, respectively.