The Santa Clara Valley Water District (Valley Water) certified a Final Subsequent EIR and approved its Permanente Creek Flood Protection Project on November 20, 2012. The project would replace sections of concrete channel on Permanente and Hale Creeks between Covington Road in Los Altos and El Camino Real in Mountain View. Bridges over Hale Creek in Los Altos would be replaced. A new diversion structure would be installed at the Permanente Diversion Channel in Los Altos. Flood detention facilities would be constructed at Rancho San Antonio County Park (Cupertino) and McKelvey Park (Mountain View). Floodwalls would be installed along Permanente Creek between US-101 and Amphitheatre Parkway in Mountain View. A 500-foot section of the existing west bank levee of Permanente Creek north (downstream) of Amphitheatre Parkway would be raised 2 to 3 feet.
This Addendum to the Final Subsequent EIR proposes to retrofit the existing eastern bank floodwall located along Permanente Creek between US-101 and Charleston Road to meet the Federal Emergency Management Agency (FEMA) stability criteria for purposes of updating the 100-year floodplain map. The proposed project changes would involve widening and thickening of the footings for approximately 1,300 linear feet of the floodwall. Pre-construction activities would include surveys, staging, and materials/equipment delivery. Construction activities for retrofitting floodwall footings would consist of excavation, concrete pouring, and backfilling. Upon completion of floodwall footings, the site would be restored, and the existing levee crest and pedestrian trails would be repaired.