Project Size: 37 acre-feet detention basin, 1.5 miles of storm pipe design
Project Description: The land use plan in a long-established area of Phoenix did not take into consideration future development and watershed runoff changes. Watershed runoff had been greatly reduced through subsequent residential development in and around the area.CVL coordinated efforts between the City of Phoenix and Salt River Project design teams to create a new area drainage master plan, detention basin, and storm drain system.
Value Added: The project consisted of a Area Drainage Master Plan (ADMP) including HEC-1 Model; the design of a 37-acre-feet Detention Basin including soccer field lighting; Low Flow Channel and Outlet Structure design; 0.5 mile 78 inch, 0.5 mile 60-inch, and 0.5 Mile 42-inch storm drain design; and Hydraulic Gradient matching the Salt River water surface.
Because each of the developable sites contained site-specific retention that reduced overall watershed runoff, CVL was able to downsize from a 108-inch storm pipe to a 78-inch storm pipe. That alone saved the City of Phoenix approximately $3 million in construction costs.
CVL evaluated other, less costly, alternatives for backfill. CVL ultimately determined that if City of Phoenix would annex property along 27th Avenue, the project could be constructed using local municipal code standards, which permitted native backfill material. Using native backfill material enabled the City of Phoenix to save approximately $900,000.