SASM News Details

WWTP Rehabilitation Project Update for September 17, 2018

The Sewerage Agency of Southern Marin launched their 2-year, $20 million Waste Water Treatment Plant (WWTP) rehabilitation project in April 2018. Improvements include infrastructure modernization, increased reliability and efficiency, electrical upgrades, and odor reduction. The project is now 25% complete.

Construction work continues to progress on schedule and on budget. Work completed since the August monthly update includes:

  1. Completed the installation, performance testing, and commissioning of the new mechanical Bar Screen #2, electronic controllers, plus the installation of several waste water flow level sensors using ultrasonic echo sensing and radar technology located within the Headworks building.
  2. Completed all concrete repairs including an application of a 240 mil thick polyurethane spray coating to Primary Clarifier Bays  #1 & #2
  3. Removed the 35-yr old plastic media from Trickling Filter #2, sand blasted and epoxy coated the 30-inch diameter influent pipe, completed necessary repairs to the structural aluminum frame, installed an interior tank plastic liner, installed media support grating, then stacked and placed over 3,100 (2-ft x 4-ft) bales of new plastic TF media.
  4. Completed the replacement of two large water gates that control treatment process flows located at Recirculation and Effluent (R&E) Pump Building.
  5. SASM WWTP Phase 1 Update as presented at the SASM Board of Commissioners meeting on September 20, 2018.

The next 4-week look ahead involves the installation of the new mechanized water rotary distributor system for Trickling Filter (TF) #2. The final stage involves the “seeding” of TF#2 with partial treated wastewater which is continuously ‘trickled’ or sprayed over the plastic TF media. As the water migrates through the pores of the plastic filter media, organics are then degraded by the biofilm covering the filter material. This seeding process takes 3-5 weeks until the bacteria are populated and mature enough for the trickling filter process to become fully operational and functional.

Other planned work includes:

  1. Installing and commissioning of a new Grit Classifier, Conveyor Belt System, Bar Screen #1, and two grit pumps with associated piping.
  2. Other work within the headworks building includes the polyurethane coating of Wet Well #1, Channel #1, and the Pista Grit Chamber.
  3. The odor control system (odor control media towers, ductwork, exhaust and supply fans, PLC, electrical components, etc.) is scheduled for delivery in late September and the Motor Control Center #2 is to be delivered by early October.

Phase 1 of the project is expected to take two years and is estimated to be completed in early 2020. Construction costs will be paid through a $38 million bond approved by the SASM Board in November 2016.  The SASM Board of Directors is comprised of six member agencies – City of Mill Valley, Tamalpais Community Services District and the Alto, Almonte, Homestead Valley and Richardson Bay sanitary districts. The City of Mill Valley is the contract operator to the six-member agency in order to ensure collaboration, cooperation and to deliver efficient, cost effective and environmentally responsible services to the community.

Learn more here.