RIDOT Phase II Storm Water Management

3) Illicit Discharge Detection and Elimination

Permit Requirement:

At a minimum, the operator must develop, implement and enforce a program to detect and eliminate illicit discharges or flows into the small MS4. The management program must include a storm sewer system map showing the location of all outfalls and the names of all waters that receive discharges from those outfalls. A strategy for mapping additional elements such as, location of catch basins, manholes, pipes within the system, must be completed for those portions of the system that are associated with the investigation and tracing of illicit discharges detected from the dry weather survey of outfalls, identification of physical interconnections with other regulated MS4s, municipal construction activity projects, and catch basin inspections. The program plan must contain procedures to identify and initially target priority areas, locate illicit discharges, locate the source of the discharge, remove illicit discharges, document actions, and evaluate impact on sewer system subsequent to the removal.

The operator must inform public employees and users of the facility of hazards associated with illegal discharges and improper waste disposal.

Best Management Practices:

RIDOT will use a combination of summer interns and hired vendors to identify, map and describe all storm water outfalls. RIDOT is mapping its entire state-wide system, not just the portions in the urban and densely populated areas, as required by the General Permit. Mapping is being completed by watershed sub-basins.

The mapping effort began in 2002 when RIDOT summer interns identified and GPS located all of the storm water outfalls in the Saugatucket River and Stafford Pond watersheds. In addition to physically locating the outfalls, pertinent data regarding each outfall is recorded on a specially-designed field report form. Photo documentation is also collected. Construction design plans are reviewed and used as a basis for field locating outfalls. Often plans are not available, so outfalls are located by finding catch basins in the field and then following them to their discharge location. During the outfall identification and location process, the outfalls are surveyed for dry-weather discharges to potentially identify illicit connections to the RIDOT system. Dry weather flows are sampled for temperature, pH, conductivity, and bacterial contamination, as required by the General Permit. Based on the results of the dry weather flow surveys and sampling, it may be necessary to trace flows up the pipe to identify the connection point. As catch basins, manholes, and pipes are investigated, these additional elements will also be GPS located and documented. Various methods of tracing are available, including smoke or dye testing, or video. If an illicit connection is found, RIDOT will work with the responsible party and RIDEM to remove the connection. All actions will be documented in a specifically designed database, and will be reported in the Annual Reports submitted to RIDEM each year.

The General Permit requires that to the extent allowable under State law, RIDOT must prohibit and enforce, through an ordinance or other regulatory mechanism available to the operator, un-authorized non storm water discharges into the system. RIDOT does not have the authority to establish such an ordinance, and will rely on RIDEM for enforcement, should it be necessary.

The University of Rhode Island Cooperative Extension will provide training and public information regarding the hazards associated with illegal discharges.

Links

• RIDEM Fact Sheet

Minimum Control Measures

4) Construction Site Stormwater Runoff Control
5) Post-Construction Stormwater Management in New Development and Redevelopment
6) Pollution Prevent/Good Housekeeping for Municipal Operations