Farallon coordinated stormwater permitting requirements for the project, which involved construction of five communications towers, and prepared and submitted construction Stormwater Pollution Prevention Plan (SWPPP) documents, allowing the client to begin construction on time.
A telecommunications client planned to construct communications towers and associated equipment at three locations on land owned by the National Forest Service and two locations on land owned by the U.S. Department of Defense. Because the five construction projects were part of a single development plan and cumulatively exceeded 1 acre of disturbed ground, a permit was required under the State of California General Permit for Storm Water Discharges Associated with Construction and Land Disturbance Activities. The varying terrain of the sites required a unique stormwater risk calculation for each site that could then be combined into an overall risk-level determination for the entire project. Site-specific risk calculations taking into account soil conditions and topography were performed and resulted in the project being assigned Risk Level 2, a lower risk level with fewer compliance requirements than the default values through the California State Water Resources Control Board’s auto-populated calculation, which would have assigned Risk Level 3 to the project. In addition, the rocky and steep slopes, with three peak sites located at over 9,000 feet in elevation and covered in snow for over 6 months per year, created unique conditions for implementing erosion prevention and sediment control methods.
A Senior Engineer at Farallon conducted a post-construction water balance and selected appropriate best management practices for the project. Based on the water balance, unique stormwater capture measures were developed and implemented at two sites to reduce peak runoff at the 85th percentile, 24-hour storm event to not exceed pre-project runoff. Farallon prepared one SWPPP for the entire project, and submitted the SWPPP and supporting technical documents to the California State Water Resources Control Board on behalf of the client.