Nestled along Crissy Beach in San Francisco, California, this transformative project centered on a significant Caltrans stormwater outfall pipe. This pipe plays a vital role in directing rainfall and runoff from Doyle Drive into the Bay area. The existing outfall, terminating at the shoreline, encountered ongoing challenges due to sand accumulation from tidal movements, leading to costly excavation and clearance efforts.
The solution was enlargement of the existing 42-inch HDPE pipe (high-density polyethylene pipe) to a 54-inches diameter and extending it approx. 500 feet into the deeper waters of the Bay. This expansion was completed by utilizing sheet pile shoring, deep excavation, dredging, and installation of an underwater cross bracing structure.
Our project encountered two major challenges. First, the site's environmental sensitivity, situated within a National Park, required meticulous adherence to agency regulations. Second, we faced a demanding timeline of just 10 weeks.
The expansion not only resolved the clogging issue but also significantly improved the efficiency and longevity of the vital stormwater management system. We completed the project ahead of schedule with zero environmental incidents.
"Although our project was carefully designed and planned it was in a terrestrial and environmentally sensitive marine area and was also under a very tight construction window. This was of great concern to us. Power had to adhere to some very strict project specifications and permit conditions. Power’s communication with their client in the form of Bidder Inquiries, RFI during construction, problem solving skills, and expertise significantly aided in a high risk project to be completed with minimal issues and ahead of schedule. Their communication with us throughout the project was invaluable."
-- Peter Aguilera, P.E., Project Engineer, CalTrans