Caltrans Maintenance Station Wash Racks Discharge Study

Client: California Department of Transportation

Prime Contractor: MACTEC

Location: Northern and Central California

Period of Performance: December 2006 - June 2007

Project Description: The Caltrans Maintenance Department was proposing to remove the Recycle Process Units (RPUs) from some of its wash rack facilities. The wash rack facilities selected for this study employed RPUs to recycle wash water for reuse. The purpose of this study was to characterize unrecycled waste water generated during the vehicle washing process at each study location in order to verify that it could be safely discharged into leach fields. In addition, samples were collected from the effluent of the RPUs at selected study locations in order to evaluate RPU performance.

ADH, as a subcontractor, under the 43A0127 and 43A0208 contracts, supported Caltrans sampling efforts by providing personnel to sample water discharging from the oil/water separators while maintenance crews were actively washing vehicles. ADH was responsible for performing aspects of the sampling program at five maintenance stations located within Caltrans Districts 1, 4 and 5 including Bracut-Eureka, Garberville, Willow Creek, Gilroy, and King City. Samples were collected from three locations: pretreatment effluent, source water, and RPU effluent. The sampling at each site occurred during three mobilizations. The samples taken during each mobilization were as follows:

• Mobilization 1: Sample three vehicles for:
  • Primary Constituents List of pre-effluent
  • Generate one set of field blank and field duplicate samples
• Mobilization 2: Sample three vehicles for:
  • Source water and RPU effluent
  • Two Primary Constituents List of pre-effluent
  • One Expanded Constituents List of pre-effluent
• Mobilization 3: Sample four vehicles for:
  • Three Primary Constituents List of pre-effluent
  • One Expanded Constituents List of pre-effluent

ADH Responsibilities:

• Coordinated sampling activities with respective Caltrans maintenance facility staff.
• Reconfigured certain maintenance station’s wash rack piping using site-specific diagrams to allow for monitoring of wash water without influence of the RPUs. Removed any installed component upon project completion.
• Collected Primary Constituents List for total metals, nutrients, conventional perimeters, and organic perimeter.
• Collected Expanded Constituents List for microbiology, metals, inorganic and conventional perimeters, organic compounds and petroleum hydrocarbons.
• Coordinated efforts with analytical labs.
• Prepared samples for overnight or same day delivery to the analytical laboratories.
• Generated extensive field and corresponding photographic documentation including: monitoring vehicle and equipment washing discharges; and, general observations of weather conditions, site conditions and concerns.