City of San Mateo Digester Tank Cleaning

CLIENT: City of San Mateo
LOCATION: San Mateo, California
SERVICES: Inspections and Condition Assessment, Wastewater Treatment Plant Cleaning and Maintenance


Work included annual cleaning of one egg-shaped digester tank approximately 100-ft. tall and 60-ft. in diameter. The City of San Mateo could not remove sludge effectively enough to allow for Pipe & Plant to access the tank from the manway on the site, so we were required to remove all sludge from the top of the digester using our proprietary submersible pumps.


Our digester tank cleaning crew had to first purge the tank using nitrogen to prevent any exposure to toxic gases. Normally, a pump would be inserted into the manway access, but in this case, the manway entrance was under the debris. Instead, we lowered our submersible pumps from the top of the tank and were able to clean the entire digester.

  • Confined Space Entry
  • Material Being Processed
  • Limited Pump Access
  • Solids Dewatering
  • Permit Required Confined Space Entry
  • Pipe & Plant Propriety Pumping Equipment
  • Nitrogen Purging