Construction begins on new San Mateo sewer structure

Construction began in November and has been divided into six construction phases, with construction expected to finish in the summer of 2023. Construction crews are currently working on phase two of the project, which involves installing a large shoring wall to increase stability at the site. The next phase of the project is underground excavation, which will begin in early 2021.

San Mateo is building the underground structure to eliminate sewer overflows and regulatory violations along the South Delaware Street corridor after an order to make changes from the Regional Water Quality Control Board. Current sewer overflows occur when the South Delaware sewer trunk line overflows during heavy rains and enters the city streets. UFES could temporarily route diluted wastewater from the sewer trunk line to the underground structure to store it for up to 24 hours. The city expects to use the underground structure fewer than 20 times a year on average.

The UFES project is part of the San Mateo Clean Water Program, a 10-year capital infrastructure improvement program to repair sewage conveyance and wastewater treatment infrastructure. Its system affects 170,000 residents on the Peninsula and is a partnership between San Mateo and Foster City. San Mateo picked the site after public hearings and meetings and determining it was the most feasible option. Anderson Pacific Engineering Construction was awarded the contract in June for construction. The structure is at the San Mateo County Event Center property between Saratoga Drive and South Delaware Street in San Mateo.

Phase one of site preparation for construction took three months to complete. The UFES project is currently at phase two, which is installing a large shoring wall, which takes three months to finish. Phase three of excavation will take five months, while phase four works on the structure’s stability, which will take two months. Phase five of structural work will take about 20 months, including the construction of walls, bases, columns, roof and installation of mechanical and electrical equipment. Phase six of the site includes finishing around the building and will take eight months.

Construction work on Saratoga Drive and Delaware Street will happen throughout the project, affecting pedestrian, bike and vehicle traffic lanes on the street. The work on Saratoga Drive and Delaware Street will build a sewer diversion system underneath that routes water to and from the existing sewer trunk line.

San Mateo will utilize traffic control while construction is happening. Traffic control and lane closures will begin in January and happen while the city builds the sewer structure. Street construction work will occur during the day, and there is no planned work on weekends. Construction work hours at Saratoga Drive will be 8 a.m. to 4 p.m., while work at Delaware Street will be from 8 a.m. to 5 p.m. Work hours at the underground sewer structure will occur Monday to Friday, 7 a.m. to 7 p.m. The city is also monitoring noise, vibration, dust and groundwater disturbances to ensure construction does not exceed allowed levels and disrupt neighborhoods.

Residents at a UFES public meeting last week asked for more clarification on construction start times, noise monitoring and more details on traffic control. People can sign up for more information and updates about the project on the San Mateo Clean Water Program webpage.

curtis@smdailyjournal.com

(650) 344-5200 ext. 102