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A <br />Project Lead <br />Location <br />Land Owner <br />650 acres <br />— Storm drain <br />— Open channel <br />IL Site parcels <br />Potential drainage area <br />Redwood City <br />Red Morton Community Park — McGarvey Field <br />Redwood City <br />Receiving Water Arroyo Ojo (tributary to Redwood Creek) <br />Jurisdiction. ...San Mateo County1c <br />Capture Area (acres) 1,142 467 41 <br />Percent of Capture 69.2% 28.3% <br />Area <br />2.5% <br />This concept describes a regional stormwater capture project for Redwood City. The <br />project, which would serve as the cornerstone for the City's MRP compliance and <br />water resiliency efforts, is envisioned as a subsurface infiltration gallery located at <br />Red Morton Park (see map to left). This project has the potential to supplement <br />groundwater supplies, alleviate flooding, offset water use at the park, and improve <br />downstream water quality in the Arroyo Ojo and downstream Redwood Creek. The <br />project has potential to treat runoff from a total of 1,650 acres, approximately 70% of <br />which is in Redwood City. The remaining 30% of the potential drainage area is from <br />Woodside and the unincorporated communities, Emerald Lake Hills and Kensington <br />Square. This may present an opportunity to explore co -funding options with <br />Woodside and the County. The project is envisioned as a single subsurface gallery <br />with potential for additional phases to be considered in the future. A multi -phase <br />approach will allow for flexibility in procuring funding and coordinating with scheduled <br />park improvements (e.g. resurfacing of turf fields). The first phase of the project has <br />potential to capture and treat approximately 31.2 ac -ft, 72% of the 85th percentile, 24- <br />hour runoff volume (43.2 ac -ft). The project can potentially reduce PCBs load by <br />16.7%. This benefit may offset the amount of green streets that would otherwise <br />need to be implemented to meet permit and TMDL requirements, reducing Redwood <br />City's green street requirement by 92.6%. Project details and costs are outlined in <br />further detail in the subsequent pages. <br />■ Hydrograph <br />60 <br />50 <br />Hsi, <br />30 <br />20 <br />O <br />LL 10 <br />X <br />■ Phase I <br />■ Rainfall (85th Percentile Storm) <br />0.0 <br />0.1 <br />0.2 <br />0.3 <br />0.4 <br />0.5 <br />0.6 <br />0 4 8 12 16 20 24 28 <br />Time (hours) <br />Sizing Criteria <br />Total Capture Area <br />Imperviousness <br />Rainfall Depth: <br />Design Total Runoff <br />Conditions for Volume: <br />85th %-ile <br />storm peak Flow Rate: <br />Regional Stormwater Capture Project at Red Morton Community Park <br />Project Overview and Drainage Area Map (Sheet 1 of 3) <br />CD <br />n <br />C <br />N <br />0 <br />7 <br />85th percentile, 24-hour storm <br />1,650 acres <br />34% <br />0.85 inches <br />43.2 ac -ft <br />41 cfs <br />Water Pollution <br />Prevention Program <br />A <br />PARDIGM <br />E N V I R O N MEN T A L <br />