BOARD AGENDA MEMORANDUM
Government Code ? 84308 Applies: Yes ? No ?
(If "YES" Complete Attachment A - Gov. Code ? 84308)
SUBJECT: Title
Adopt Plans and Specifications and Authorize Advertisement for Bids for the South Babb Flood Mitigation Project, under the Watersheds Asset Rehabilitation Program, Project No. 62084001, Contract No. CO716 (San Jose, District 6).
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RECOMMENDATION: Recommendation
A. Approve the South Babb Flood Mitigation Project;
B. Adopt the Plans and Specifications and Authorize Advertisement for Bids for Construction of the South Babb Flood Mitigation Project per the Notice to Bidders; and
C. Authorize the Designated Engineer to issue addenda, as necessary, during the bidding process.
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SUMMARY:
South Babb Creek is a tributary to Lower Silver Creek, which is a 43.6 square mile drainage area within the larger Coyote Creek watershed. The entire section of South Babb Creek is located within the City of San Jose and drains into Lower Silver Creek downstream of the Farringdon Drive bridge.
In 2018, Santa Clara Valley Water District (Valley Water) completed civil construction of floodwalls as part of the Lower Silver Creek Project at the confluence with South Babb Creek. Following construction, Valley Water completed a 100-year flood event study that included a hydrologic and hydraulic model of the Lower Silver Creek watershed in support of the Federal Emergency Management Agency's (FEMA) Cooperating Technical Partnership program. The results of the hydraulic modeling indicated that, in this event, flood water would spill along South Babb Creek onto the street surface at several bridge crossings. Flood waters would then flow north easterly and pond behind the floodwalls constructed for the Lower Silver Creek Project (Reach 5C), preventing overland drainage back into the creek. The water eventually would flow to the north and flood an apartment complex. FEMA has initiated a Physical Map Revision based on the recent hydraulic mo...
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