Caltrans Storm Water Quality Study - Long-term Discharge Characterization

Client: California Department of Transportation

Prime Contractor: MACTEC

Location: Camp Roberts Rest Area, Highway 101, Monterey County, California

Period of Performance: Ongoing since October 2007

Project Description: In 2000, Caltrans initiated a three-year Statewide Stormwater Runoff Characterization Study (Statewide Study) to characterize stormwater runoff at representative transportation facilities. The Statewide Study gathered stormwater runoff data at these facilities for the purpose of meeting National Pollution Discharge Elimination System permit requirements, providing data for best management practices (BMP) research and development, assisting in the development of stormwater modeling and other load assessment efforts, and developing a scientifically-robust characterization data set for Caltrans facilities. This Long-Term Discharge Characterization (LTDC) Study, as mandated by the California State Water Resources Control Board, follows the Statewide Study and continues Caltrans' effort to take a multi-faceted approach to ensure the scientific validity, comparability and representativeness of stormwater data collected under variable conditions in diverse regions, by multiple organizations. Data collected under the LTDC study will add to results of the Statewide Study and allow for more robust analysis of stormwater runoff for the following purposes: supporting research and development needs; providing inputs for load assessment and modeling efforts; providing useful information for watershed planning; and, supporting scientifically-sound statistical data quantification.

For this discharge characterization monitoring program, ADH was responsible for two locations within Caltrans District 5 including the Camp Roberts' rest area and Ano Nuevo [site also used for the Areas of Special Biological Significance (ASBS) site 15]. Three storm events were monitored at each site for this study during the 2006-2007 wet weather season. For the one season this study was performed, ADH was responsible for the following:

• Installation, maintenance and operation of automated, flow-weighted stormwater quality composite sampling and monitoring stations. ASBS 15 monitoring station was reconfigured to accommodate two composite sample bottles so that storm events could be simultaneously monitored for the LTDC and ASBS studies.
• Storm event forecasting.
• Storm event monitoring; composite and grab sample collection, toxicity sample collection.
• Remote instrument communication for data acquisition and programming control.
• Preparation of samples for overnight or same day delivery to the analytical laboratories.
• Field documentation.
• Coordination with analytical labs.
• Preparation of Post Storm Technical Memoranda components.
• Equipment demobilization.
• Review and editorial comment on the annual monitoring report.
• Participation in technical advisory meetings.