Improving Effluent Water Quality at a Remote Facility

Considered a small and remote community, Fort Bragg lies on California’s Pacific coast, along Shoreline Highway in Mendocino County. Although primarily a tourist destination because of its picturesque views of the ocean and its famous Glass Beach, 7,273 people consider Fort Bragg their home. The nearest major city is 137 miles away on a single-lane, congested highway, making access to resources very limited.

The City’s wastewater treatment plant operators needed to replace several pieces of equipment. But due to the remote location, there were no provisions available to remove major components from service and replace them. If the City took portions offline, it would violate permit effluent limits and incur fines. Therefore, the entire treatment system required an upgrade.

Located a few feet from the ocean, the wastewater treatment plan was renovated to address aging facilities, ease maintenance requirements, accommodate future growth and improve effluent water quality. Plant improvements included replacing the existing trickling filters and clarifiers with an Aero-Mod SEQUOX activated sludge system; converting the clarifiers into equalization basins; repurposing the trickling filter concrete slabs for biosolids storage; adding a new influent pumping station; adding a new, on-site stormwater pumping station to capture and treat water prior to discharging to the ocean; installing a new pumping station to lift the influent to the activated sludge system; and adding a new building to house the blowers for the treatment process and a new belt filter dewatering press. The design specified high levels of energy efficiency, alternate energy sources to power the treatment train and alternate use of treated effluents and sludge. 

The $15.4 million WWTP upgrade was the largest and most complex project the City ever endeavored. It required substantial resources to construct such a project including skilled labor, heavy equipment and substantial supplier coordination. With limited resources and a remote location, the project required a lot of flexibility, including design modifications during construction. This flexibility enabled the city to complete the project on time and within budget. 

The new treatment system achieved increased reliability, in terms of treating highly variable organic loadings and significantly improving the final effluent water quality for discharge.