Thirty percent of state DOTs have produced manuals or internal guidance for stormwater protection at non-highway maintenance facilities. General practices for maintenance of stormwater facilities include the following:

• Maintenance Supervisors should be charged with line responsibility for inspecting stormwater drainage systems and assessing the need for cleaning or clearing.
• The DOT should observe culverts and drain inlets annually in the fall and throughout the winter as needed to determine if cleaning or repairs are required.
• Culverts should be cleaned when sediment impairs culvert function.
• Ditches should be cleaned prior to the rainy season to maintain the hydraulic capacity of the ditch.
• Ditches and gutters should be sealed or repaired when structural integrity is endangered.
• Downdrains should be inspected annually and cleaned or repaired as necessary.
• Solid and liquid wastes generated by the cleaning of stormwater drainage system facilities should be disposed of in accordance with federal, state and local liquid and solid waste disposal regulations.
• Baseline inspection and cleaning activities should be reported annually by section of highway and information used as a tool to evaluate the program.

MDSHA has mapped the entire state for opportunities for retrofitting BMPs, for pollution prevention and stream restoration beyond requirements. The agency has developed a thorough and duplicable grade-based rating system for stormwater management facilities and has developed an inventory, database, and photo record of all facilities statewide and their maintenance status. Inspection teams of trained staff identify further environmental improvements that can be made. Under the rating system, those graded A or B are considered functionally adequate. As of late 2003, between 73 and 75 percent of MDSHA stormwater were functionally adequate (A=everything fine, working fine, no maintenance required, B= minor maintenance, need mowing or trash removal), leaving approximately 25 percent needing maintenance or retrofitting to achieve functional requirements. The state is developing and implementing a plan for systematic implementation of those improvements. By 2010 MDSHA is aiming for 95 percent of facilities functioning adequately.[N]

Mn/DOT system for inventorying hydraulic conveyance structures, a requirement in many states for NPDES Phase II, is called "HYDRINFRA." Mn/DOT plans to add an inventory of ditches and erosion problem areas to the database in the future. Mn/DOT employs consultant services for three levels of inspection, location, and repair of hydraulic structures.

• MS4/HydInfra Inspection may include inspection, GPS location of hydraulic structures, and/or development of an electronic map ("stick map") showing all hydraulic structures located during either the inspection and/or cleaning. The map will also show flow connection and direction for all structures as listed above and rating/evaluation of hydraulic structure condition. Any indicators of illicit discharges to the system are noted on reports.

Figure 17 : Field Crews Collect Information on Stormwater Retrofit Needs at MDOT Stream Crossings

• Video Inspection is completed for hydraulic structures (pipes, culverts, manholes, catch basins, drop inlets, etc.) and is conducted using remote controlled, self-propelled, explosion-proof video cameras. Video inspection includes providing video of the entire damaged structure. Defects along the pipe are identified, indexed, and stamped on the screen to allow for easier processing by Mn/DOT personnel. Video must be provided in digital (MPEG-1) format for use of storage and filing.
• Hydraulic Structure Cleaning includes removal and proper disposal (including certification) of material from all types of hydraulic structures.

Road-stream crossing features contribute varying amounts of sediment and non-point source pollutants to rivers and streams. In an effort to combat the influx of these types of pollutants, the Michigan Department of Transportation (MDOT) used federal Transportation Enhancement funds to support planning studies that inventory road-stream crossings in several locations throughout the state. These studies are used to prioritize funding for additional efforts to mitigate pollution from highway runoff. One such inventory was the Ionia County Road Commission's planning inventory of all bridge and culvert road-stream crossings in the county. As a preventative measure the study was intended to highlight potential problem locations and increase reaction times in resolving water impairment issues. Field crews from a local university collected site data from more than 700 locations. The sites were ranked and the data was entered into a Geographic Information System (GIS) that included information on soils, land use, drains, school districts, and road ratings. The project was the cooperative effort of several county agencies, MDOT, and Grand Valley State University.[N]