The Department is subject to the National Pollutant Discharge Elimination System (NPDES) Statewide Storm Water Permit Waste Discharge Requirements for State of California Department of Transportation. On April 7, 2015 the State Water Resources Control Board (State Water Board) adopted statewide Trash Provisions, collectively known as the "Trash Amendments" to address pervasive impacts trash has on the beneficial uses of surface waters. On June 1, 2017 the State Water Board issued a letter regarding Water Code Section 13383 Order to Submit Method to Comply with Statewide Trash Provisions to the California Department of Transportation. On April 12, 2019 the Department submitted the Statewide Trash Implementation Plan stipulating the Track 2 compliance track as well as providing the mapping of the Significant Trash Generation Areas (STGA). The Department is in the process of developing and implementing trash treatment control devices that meet the Full Capture System definition while simultaneously meeting the requirements of the Highway Design Manual (HDM) and the California Department of Public Health (CDPH) Water Detention Policy for Mosquito Prevention.

This pilot evaluates the design process, construction process, operation and maintenance process of a commercially available storm drain pipe trash screen (commercially referred as a Connector Pipe Screen) that is listed as a certified full capture system trash device by the State Water Board. This pilot also evaluates whether the storm drain pipe screen meets HDM and CDPH requirements.

The pilot study will last 3 to 5 years, with the duration depending on the quality and quantity of data able to be collected over that time. The portion of the study that evaluated the design process and construction process is complete.

The design process included determining an appropriate site to conduct the pilot study that was included in the STGA and was also a low-risk area for implementing pilot devices. Once the site was chosen, As-Built research and several field investigations were conducted to determine the locations that the storm drain pipe screens could be installed and to determine where to install the storm drain pipe screens inside the existing inlets for them to be effective. Commercially available trash screens that meet the requirements were researched, and outreach occurred with several Manufacturers. Plans were produced and provided to the Construction team.

The Construction process included determining cost of the purchase and installation of the storm drain pipe screens, coordinating with the Prime and the storm drain pipe screen installation team. During this process, the study discovered stage construction minimum areas, minimum inlet height requirements and conflicts with installing secondary riser devices. Re-designs of pipe connector screen placement, orientation and dimensions also occurred due to construction methods and screen stability concerns.

The storm drain pipe screens were successfully installed and the evaluation of the storm drain pipe screens operation performance and maintenance obligations is on-going.

Operation performance is documented by the NPDES Branch team via field visits during storm events.

Maintenance obligations is documented via coordination with the Maintenance Stormwater Crew. The Maintenance Stormwater Crew cleans the retrofitted inlets and storm drain pipe screens before and after a rain event. The NPDES and/or Hydraulics Branch teams are on site to document the trash collected and the process and effort to clean the system.

Evaluation of the storm drain pipe screens meeting HDM and CDPH requirements is also on-going. This effort includes conducting a Hydrology and Hydraulics study to determine if the storm drain pipe screens successfully pass the 25-year storm event while meeting the HDM criteria and the CDPH Water Detention Policy requirements.


Submitted by:
Carl Savage - District 11 NPDES/Storm Water Branch
Melisa Wiedemeier - District 11 Hydraulics Branch 

Team Members: 
NPDES/Storm Water Branch
    - Ian Cohan
Hydraulics Branch
    - Gerardo "Gerry" Barba
    - Oliver Asis
Construction Division
    - Gary Levine
Maintenance Division - Stormwater Crew
    - Joselito Baluyot and crew

Special thanks to:
    - Allan Kosup - North County Corridor Project Director
    - United Storm Water Inc

For more information, contact Melisa Wiedemeier at [email protected].