Reso13 PC 13-24 2920 PC Reso-Adopt the Intitial Study MND - Undercrossing

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�Enui�oonme�atalAraalysis water to the existing sanitary sewer system within in the project axea. Thu�,dewatering would not have any water quality impacts to surface or groundwaters in the axea. The stormwater discharges would comp�.y with the SMCWPPI' tequirements and the shared City of Redwood City and San Mateo County NPDES Permit No. CAS612008. '1'he discharges would be subject to e�sting monitoring and inspection requirements. The starmwater that collects in the new joint-use path would discharge through two new 18-inch pipes to Redwood Creek. The following rnitigation measures would reduce the potential impacts o£the project to water quality. Mitigation Measure HYD 1: Implementation of BMPs A Storm Water Pollurion Prevenrion Plan (Slx'PPP) shall be prepared for the project. The BMPs contained in the SWPPP shaFl be implemented, and the NPDES Pe�mit Campliance Checklist (see Appendix� to control and prevent the potential discha�ge of non-stormwater dischaYges and poAutants to Redwood Creek during construction shall be completed. The Contractar shall utilize measures such as secliment barriers, si�t fences, straw wattles, biodegradable fiber�olls, or i�ydraulic mulches to trap sediment in stormwater xunoff away during const�uction to pxevent the discharge of pollutants to Redwood Creek. The Contxactor shall revegetate the disturbed areas of landscaped vegetiatian along the cxeek banks with a hydroseed native plant mix for slope stabilizarion. The Contractor shall implement rock slope protecuon (RSP) on the cteek bank below the proposed 18-inch dtainage pipes' discharge points to prevent erosion along the creek bank. With the incorporarion of these measures,the impacts to watet quality would be reduced to less than significant levels. (Less thari Significant Impact with Mitigarion Incorporation) b)Substantially deplete groi.urdwater supplies or interfere substarltially with gtoundwater recharge such tCrat there would be a net deficit in aquifer volume ax a lawetiug of the local grarurdwater table level(e.g., the production rate ofpre-exrstir�grleatby wells wauld drop ta a level which would�ot support existrng land uses ar planried uses fot whrch permits have been granted)? Excavation for the 26-foot deep wet well at the teplacement pump station, trenching for the pipelines,and excavarian for the joint-use path would likely encounte�grout�dwater at levels belaw 2- 4 feet and need dewatering. The Ciry does not use grour�dwater for water supply wells. The requixed dewatering would affect gxoundwater levels in the immediate vicinity af the project,but would not have a substantial effect on groundwater supplies or interfere with graund�vater xecharge activities. (Less than Significarit Impact) 2-45 US �0� Pedestrian Undercrosssn�and Bair I'sland Road Stor7n Draan Prrmp Stataan I'rojec•t