Building next to an ecological reserve requires extra care and diligence to ensure that these special habitats are protected. PCL’s Special Projects division was contracted by the City of Solana Beach, California to deliver significant upgrades to the city’s primary sewer pump station which sits on the edge of the San Elijo Lagoon Ecological Reserve. The location and the physical constraints of the site required the project team to implement protective measures.
Situated 15 feet below grade, basin construction required dewatering of groundwater to reduce the potential for stormwater pollution which was a high-risk on the project. The water table, approximately three to four feet below grade, fluctuated due to ocean tides. Dewatering the basin’s location required continual diligence and a variety of tactics including drilling wells, using sump pumps and installing additional shoring. Special filters were used on the sump pumps along with a desilting tank to ensure the discharge water was exceeding the rigorous quality standards of the permit prior to discharging to the storm drain. During basin construction, the existing pump station had to be shut down for four months while maintaining the incoming flow to the station. This required using a bypass pump to divert flows to the force main, presenting risks for potential leakage and sewage spills. PCL worked closely with the trade contractor conducting the bypass work, achieving successful completion with no leaks. This solution provider approach combined with exceptional teamwork allowed the team to successfully execute the work and establish a great working relationship with the client.
Other aspects of the project included upgrades of two underground reinforced concrete wet wells, two submersible wastewater pumps, three dry-pit-close-coupled submersible pumps with five feet of 24-inch ductile iron piping and replacement of a portion of the existing CMU pump building.