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Last Updated: Thursday, January 5, 2012 1:08 PM

Multi-Chambered Treatment Trains (MCTT)

The MCTT was developed for treating stormwater at critical source areas with limited space, such as vehicle service facilities, parking areas, and fueling stations. The MCTT uses three treatment mechanisms in three different chambers. The initial chamber is a catch basin, which functions primarily as a screening process for the other two chambers by removing large, grit-sized material. The settling chamber is the primary treatment area for removing settleable solids and associated constituents with plate separators and floating sorbent pads. Oil and grease are also removed with the sorbent pads. The media filter chamber is for final polishing of the effluent, using a combination of sorption (through layers of sand and peat covered by filter fabric) and ion exchange for the removal of soluble constituents. When full, addition flows to the MCTT spill over a bypass pier set at the maximum water surface elevation.

Site Location: Via Verde Park and Ride

Directions: I-210 eastbound, left on Via Verde Road, left into park and ride, near I-210 off ramp

Site Location: Metro Maintenance Station

Directions: I-5 to 2187 Riverside Drive, under SR 2

Site Location:Lakewood Park and Ride

Directions: I-105 to southbound Lakewood Blvd., to park and ride, south of Lakewood Blvd., on west side

Automatic sampling equipment is located at the inlet and outlet of the MCTTs to collect flow-weighted composite samples (collected in proportion to the intensity of the runoff). Maintenance includes renewing sorbent pads, removing accumulated sediment, and replacing filter fabric and clogged media as necessary. The permanent pools of water require regular monitoring and mosquito abatement.


Division of Environmental Analysis, Stormwater Unit
California Department of Transportation
P.O. Box 942874, MS-27
Sacramento, CA 94274-0001
Email: Division of Environmental Analysis, Stormwater Unit