Trash Full Capture Design and Determination of Compliance
Currently installed devices (Best Management Practices) or planned installation of devices to address post-construction requirements may qualify as equivalent to full capture device or system provided that the device complies with the adopted Trash Amendment definition of a full capture system, defined as:
Full capture systems for [trash removal from flow in] storm drains are defined in the proposed final Trash Amendments as treatment controls (either a single device or a series of devices) that traps all particles that are 5 mm or greater, and have a design treatment capacity that is either: a) of not less than the peak flow rate, Q, resulting from a one-year, one-hour, storm in the sub drainage area, or b) appropriately sized to, and designed to carry at least the same flows as, the corresponding storm drain.
Treatment BMPs identified in the CASQA Stormwater Best Management Practices Handbook – New Development to identify those practices that could be considered equivalent to full capture systems. BMPs currently installed or planned for installation to meet post-construction requirements quality as full capture systems provided that the BMP provides a physical screening mechanism designed to capture trash and sized to treat the one-year, one-hour storm event and properly maintained, they should be accepted as full capture systems.
List of Approved Full Capture Systems or devices include the following:
1. Infiltration Trench (See CASQA BMP Handbook TC-10 fact sheet)
2. Infiltration Basin (See CASQA BMP Handbook TC-11 fact sheet)
3. Media Filter (See CASQA BMP Handbook TC-40 fact sheet)
4. Capture and Use Systems and Retention/Irrigation (See CASQA BMP Handbook TC-12 fact sheet)
5. Bioretention (See CASQA BMP Handbook TC-32 fact sheet)
6. Extended Detention Basin (See CASQA BMP Handbook TC-22 fact sheet)
7. Wet Ponds (See CASQA BMP Handbook TC-20 fact sheet)
8. Constructed Wetlands (See CASQA BMP Handbook TC-21 fact sheet)
9. additional list of previously approved full capture devices
Some devices (such as Constructed Wetlands or Wet Ponds) may need to have forebays where the discharge from the forebay into the BMP can trap all particles that are 5 mm or greater.
Presentation will focus on trash full capture design configurations, modifications to comply with the statewide trash amendment, and updates on CASQA's collaboration with State Board, Regional Boards, and NGOs on the full capture trash design and determination of compliance will be discussed.