AgdaPkt 2020-08-24 Joint SA PFA - Laserfiche WebLink

Browse Search

6.1 711e Ct AtAtS of a subsurface concrete gallery that will be located beneath McGarvey Field at Red Morton Community Park. The structure has potential to capture 31.2 acre-feet of runoff from Arroyo Ojo, a tributary of Redwood Creek that flows to the Bay. Storage capacity is capped at 31.2 acre-feet due to available area at McGarvey Field and a reasonable structure depth of 12 feet. The section of Arroyo Ojo just west of the park is an open channel that is routed underneath the park through a large reinforced concrete drain before daylighting to an open channel east of the park. The project will divert from the 5 -ft 2 -in by 12 -ft drain using a rubber dam system and intake basin. Runoff will be routed through a pretreatment system, such as a hydrodynamic separator, to remove solids and sediment, then pumped to the gallery. The total storage (31.2 ac -ft) will account for approximately 72% of the 85th percentile, 24-hour runoff volume (43.2 ac -ft). Captured runoff will be treated through infiltration. Stormwater reuse elements (irrigation, greywater, etc.) may be incorporated if infiltration rates are deemed too low at the site. A second phase may be considered to capture the remaining 12 ac -ft of the design volume uncaptured by the McGarvey Field structure (Phase 1). Phase II would likely be located on Griffin and Bechet Fields just west of the Phase I structure to minimize disruption of utilities on the northern half of the park. The Phase 11 facility can be constructed at a later date but may still be able to utilize some of the diversion infrastructure from Phase 1. For example, it may be possible for the diversion components to be built in parallel to make use of the same pump housing and intake structure. These design aspects should be explored in greater detail during a feasibility analysis. Disclaimer: Utilities were evaluated through GIS analysis using best available data. A utilities survey should be performed prior to construction to confirm the location of all utilities on site. ' S \� I. [ i, Lih. \ \ A DNERSION \\% PRI? REATMENTZ O �// UNIT F I/ PHASE 2 1.8 AC PHASE 1 2.6 AC DIVERSION LINE 24" RCP � f 0 100 s.+ 300 400 FT Regional Stormwater Capture Project at Red Morton Community Park � = Site Plan and Description (Sheet 2of3) Water Pollution PAR DIGM Prevention Program E N V I R O N M E N T A L