14 ATTACHMENT 1-5 - Laserfiche WebLink

PUD-138 and Vesting Tentative Subdivision Map 8616 Planning Commission 24 of 28 As mentioned earlier in the report, the proposal also includes three open space parcels: Parcels A and B would be owned and maintained by the HOA. The construction of Parcels A and B would be by the applicant as part of the project improvements. Parcel C will be retained by the Spotorno family and be permanent agricultural/open space via recordation of a conservation easement. The trail segment on Parcel C would be constructed and maintained by the HOA. Utility Plans Stormwater and Drainage The HVSP, with respect to storm drainage associated with the development of Spotorno Flat Area (Pages 75-76) requires detention of stormwater runoff from upland areas to the east, as well as of stormwater runoff which is not absorbed into the ground due to the creation of new impervious surfaces. To satisfy this requirement, two separate storm drain systems would be constructed within the Spotorno Flat Area, with pipes ranging in size from eight to 36 inches in diameter. One storm drain system would collect runoff from lots and streets , and would discharge stormwater directly to the treatment pond on Parcel A for stormwater treatment and flood mitigation. A second system (bypass system) would collect runoff from the upland area and the subdivision areas that do not require further treatment. The two systems would converge downstream of the Parcel A treatment pond and would connect to an existing 36-inch culvert under Alisal Street, although runoff in the bypass system would be diverted under high flow storm conditions to mitigate for increased site runoff. Stormwater on Lots 13-15 (lots fronting Westbridge Lane) would be treated by on-site bioretention and would be discharged directly to Westbridge Lane through curb drain systems, or similar conveyance. The HVSP regarding storm drainage also states the existing street culvert at Alisal Street at the Faith Chapel Assembly of God is an undersized street culvert. The HVSP states: “The crossroad drain lines along the Spotorno Flat Area frontage of Alisal Street will require replacement with properly sized culvert. Improved roadside drainage is also necessary.” The HVSP requires the referenced improvements be funded and undertaken by the developer of the Spotorno Flat Area prior to occupancy of new homes on the site. As the current proposal did not include these improvements, staff has added a condition of approval to address this item. Water and Sanitary Sewer The proposed project would include a 12-inch-diameter potable water pipeline that would extend along Spotorno Ranch Drive, providing connections to each residential lot. The water supply system would connect to an existing 12-inch potable water line that is located within Alisal Street and Westbridge Lane, and which is owned and maintained by the City of Pleasanton. An eight-inch sewer main would be routed within the Spotorno Ranch Drive, with lateral connections to each residential lot. The sewer system would connect to an existing eight-inch sewer line located within Alisal Street, which is owned and maintained by the City of Pleasanton. The City’s Operation Services Department has reviewed the proposed utility plans and found they are acceptable. During the construction of Callippe Preserve Golf Course, the City constructed and fronted the cost of constructing all water and sanitary sewer facilities required for the Golf Couse , Golf Course housing, and development in the HVSP area. The owners of existing homes and the