Combatting a cease and desist order in San Mateo

Basins 2 and 3 Collection System Improvements Project

When the City of San Mateo received a cease and desist order requiring improvements to its collection system, they brought us in to help with their Clean Water Program. The cease and desist order obligated the City of San Mateo, Town of Hillsborough, and the CSCSD to complete improvements necessary to eliminate conditions in its collection system that cause or contribute to sanitary sewer overflows (SSOs).

Our job? Providing design services to upgrade aging infrastructure, enhance reliability, and improve capacity for wet weather flows in the collection system. There were three major components. First, a new 4.2 million-gallon (19.1 million litres) in-system flow equalization storage facility was installed. After that, we upgraded and expanded three existing pump stations.

The final component involved the installation of approximately six miles (nine kilometres) of new parallel and upsized gravity sewers and force mains, along with rehabilitation of existing infrastructure. The project also included four challenging urban horizontal direction drilling (HDD) crossings for the 14-inch (35.6-centimetre) high-density polyethylene pipe (HDPE) ranging in lengths from 480 feet (146 metres) to 1,150 feet (351 metres).

With these upgrades in place, the City of San Mateo, Town of Hillsborough, and the CSCSD were prepared to eliminate sanitary sewer overflows during design-level storm events.