AgdaPkt 2016-04-25 Closed and Joint SA PFA

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Project L7.B. - Page 31 approximately 700 feet long and would pass under the US 101 freeway bridge between the northern bridge abutment and Redwood Creek. The joint-use path would connect the recently completed Class I and II bike paths on Bair Island Road to the existing Class II bike path on Main Street. There would be approximately 9 to10 feet of headspace between the path and the soffit of the bridge. A battered tieback wall would be implemented on the abutment side,and a cantilevered retaining wall would be installed on the creek side of the path. The top portion of the wall between the path and the creek would utilize a 1-foot high metal railing,which would allow passing pedestrians and bicyclists to have views of the creek. Landscaped retaining walls would extend beyond both entrances to the path under US 101. The base of the path would slope from an elevation of 6.9 feet on the east end to 5.8 feet on the west end under US 101. A drainage system would capture and detain stormwater as needed prior to discharge to Redwood Creek through one 24-inch drain pipe. In addition to the 14-foot wide joint-use path, the project also includes enhancements on the City- owned parcel south of Convention Way including a 12-foot wide sidewalk,pedestrian lights, landscaping trees along the south side of Convention Way,and a scenic overlook with decorative seating looking toward Redwood Creek. The path would have security access gates at each entrance to the path and call boxes linked to City dispatch or 911 at the west and east ends of the underpass. City maintenance staff would close the gates to the path during unsafe conditions, such as high water levels or seismic events. The proposed storm drain pump station would consist of two 90-hp submersible pumps and a low flow pump in a wet well,a concrete vault,an emergency generator,and interconnecting piping. The 2,900-cubic foot wet well would be approximately 12 feet in diameter and approximately 26-feet deep with a concrete base atop one foot of compacted drain rock. The wet well would collect the water from the Bair Island drainage area,and the variable speed pumps would be able to discharge a peak flow up to 32.4 cfs. The 5-foot deep concrete vault would contain valves for controlling the flow from each pump. The 250-kW emergency generator would be housed on an 8 foot by 10 foot generator pad. A 500-gallon diesel storage tank would store at least a 24-hour fuel supply for the standby generator. The pump station would have electrical service and an Advanced Digital Network for the Supervisory Control and Data Acquisition (SCADA) system to monitor the operation of the pump station system. Ground level access hatches would cover the underground wet well and vault. The pump station would be located approximately 130 feet east of the traffic circle on Bair Island Road, north of the alignment for the planned Blomquist Street extension. A paved driveway from Bair Island Road to the new pump station would also be installed. Approximately 35 linear feet of new 42-inch storm drain ductile iron pipe (DIP) would be required to redirect the flow from the existing storm drain system within the 22.28-acre Bair Island Road area to the new pump station. Approximately 100 linear feet of 24-inch DIP would be used to convey the flow from the new pump station to the existing 24-inch pipe outfall that discharges into Redwood Creek. The point of connection with the existing drain line would depend on the condition of the existing 24-inch pipe. 1-5 US 101 Pedestrian Undercrossing and Bair Island Storm Drain Pump Station Project