ODOT is required to hold a National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit issued by the Oregon Department of Environmental Quality to operate the ODOT stormwater system. The permit requires ODOT to inventory and manage stormwater outfalls associated with the ODOT stormwater system. ODOT has prepared an inventory of its stormwater outfalls, but these records can be difficult to read and understand.
Stormwater outfalls are one of several stormwater treatment facility components specially configured to assist with the conveyance of runoff before leaving the state’s highway system and entering a receiving water body. Outfalls typically convey water from either a stormwater treatment facility or a stormwater piping system to a point of discharge, where water enters a natural water body or another drainage conveyance system.
Stormwater outfalls are integral parts of the state highway system and like other infrastructural elements, they are subject to deterioration. ODOT is responsible for maintaining these components as part of its operation and maintenance of stormwater treatment facilities, in an effort to more effectively remove highway pollutants from stormwater runoff before they re-enter the natural environment.
In support of the NPDES MS4, ODOT has provided an inventory of its stormwater outfalls located along the state’s highways. The focus is on outfall pipes discharging to a water body.
Outfall Inventory Project
ODOT has begun a new project where new and existing ODOT outfall information is being collected and formatted so a GIS map can be produced that clearly depicts location of ODOT outfalls. The project is focused specifically on mapping ODOT outfalls located in MS4 NPDES permit areas because DEQ has identified these areas as high risk for stormwater impacts to receiving waters.
Long Term Effort
ODOT has been working for a number of years on organizing highway inventory information into a format that is more usable for GIS mapping. This project is part of that effort. ODOT’s long term goal is to eventually produce maps that depict various highway features associated with ODOT right of way, stormwater outfalls being one of those highway features. A summary of ODOT outfall inventory information gathered to date for this project. ODOT is currently in the process of developing a user-friendly map that will be posted soon.
Over 600 stormwater outfalls have been inventoried within Phase I/II municipal boundaries and are shown in the map files listed below:
An important task of ODOT Maintenance is keeping the highway drainage system functioning. Roadside ditches are cleaned and reshaped, removing accumulated sediment and debris that reduces capacity and restricts flow. As part of it's Ditch Inspection Program, ODOT also inspects and cleans highway ditches to ensure adequate structural status and to protect water quality. The Ditch Maintenance Log (June 2010 to present) is a quarterly report that shows which state highway ditches have been maintained and the cost of that maintenance.