For the City of Pacifica’s $22M Wet Weather Equalization (EQ) Basin project, 4LEAF provided comprehensive project management, construction management, and inspection services, building upon initial support delivered during the geotechnical investigation, design, and CEQA evaluation phases. Developed to eliminate capacity-related sanitary sewer overflows (SSOs) during the rainy season, the multi-award-winning project was recognized as the “2020 Environmental Project of the Year” by the San Francisco Section of the American Society of Civil Engineers (ASCE).

The extensive scale of the project centered on two primary elements: a massive 2.1-million-gallon rectangular EQ basin and critical diversion structures with extensive conveyance piping. 4LEAF’s oversight spanned complex neighborhood coordination, daily noise monitoring, public outreach, and compliance with the CEQA Mitigation Monitoring and Reporting Plan. Key construction milestones managed by the team included in-situ waste characterization for 23,000 cubic yards of excavated soil, a perimeter sound wall, a 3-foot-thick outer concrete cutoff wall reaching depths up to 70 feet, 72 deep micropiles, a 5-foot-thick reinforced concrete mat slab with a 2-foot-thick inner concrete liner wall, complete mechanical and electrical systems commissioning, jack-and-bore steel casing, and 1,600 feet of HDPE gravity sanitary sewer conveyance piping.