Upgrades Coming to Water Treatment Plant

The South San Francisco and San Bruno city councils had a joint meeting Tuesday night to discuss required changes to their shared water quality treatment plant as part of the State Water Board’s re-permitting process.

Under the current system, sewage passes through two levels of treatment in the plant before passing through a pump station shared with Burlingame, Millbrae and SFO and being released into the San Francisco Bay.  But during storms, excess water leaks into the sewage pipes and overwhelms the system. 

When this has happened, the plant has dealt with the overflow by releasing treated wastewater directly into Colma Creek or by releasing some partially-treated wastewater into San Francisco Bay, according to Michael Britten, engineer for the Carollo Engineers, the contractor for plant upgrades.  Such an event has happened only once since 2005, when the plant installed a storage pond, Britten said.

The State Water Board now requires the plant to create and implement a plan to eliminate discharging into Colma Creek entirely and to reduce the release of partially-treated wastewater (which is mixed with fully treated wastewater before it is released in rare storm conditions.)

Britten proposed that the councils pursue further environmental studies to show that occasionally discharging into Colma Creek during wet conditions is safe and seek to a permit to continue to do so.  Barring that option, the plant will need to install an additional backup storage tank, estimated to cost $12 million.

The upgrades to the plant will also include facilities and green energy upgrades.  The cost over the next five years is estimated to be $22 million, with South San Francisco responsible for $16.4 million and San Bruno responsible for $5.6 million.

Both councils will need to approve the facilities plan at future meetings to proceed.