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Case Study Location: Michigan: Wayne County

Case Study Title: Focus on Commercial and Industrial Site Visits

Minimum Control Measure: Illicit discharge detection and elimination

Wayne County, Michigan's Water Protection LogoThe Wayne County, Michigan, Department of Environment conducted an investigation of 5,753 nonresidential facilities from 1987 to the present to detect and eliminate illicit connections and illicit discharges.

Location: Michigan: Wayne County
Annual Rainfall: 31 inches
Population: 2,061,162
Year the Program Started: 1987

Contact Information:

Dean Tuomari
Wayne County Department of Environment, Watershed Management Division Exit EPA Site
3600 Commerce Ct
Wayne, MI 48184
Phone: (734) 326-4483  
Fax: (734) 326-4421


Wayne County encompasses 33 cities and 10 townships in Southeast Michigan, including Detroit. Since 1987 Wayne County has conducted a comprehensive illicit discharge detection and elimination program. The purpose of the program is to prevent the introduction of pollutants into storm sewers and surface waters from sources such as improperly plumbed connections, material dumped onto the ground, and discharges from outdoor activities that generate significant pollutant loads. The program involves water quality monitoring; geographic targeting and drainage area prioritization; facility inspections and dye testing; and enforcement at the local, county, and state levels. From the program's inception in 1987 through December 2003, 5,753 facilities were inspected and 1,483 illicit connections were found at 417 facilities. Approximately 7 percent of the inspected facilities had illicit connections and those facilities with illicit connections tended to have more than one (an average of 3 to 4 illicit connections per facility). As part of the Rouge River National Wet Weather Demonstration Project, Wayne County has developed guidance and numerous publications that detail its program and describe lessons learned in developing and implementing an illicit discharge program. Wayne County estimates that the program annually prevents more than 12.5 million gallons of polluted water and 1 million pounds of polluting material from entering Wayne County surface waters.

Pie chart showing illicit connections found at commercial and industrial facilities
Based on 17 years of experience, Wayne County has found that an effective approach to eliminate illicit discharges to surface waters is one that is based on a combination of focused attention in areas with known water quality problems and site visits to facilities. Wayne County's illicit discharge program is based on four main elements: choosing an area for investigation, developing a facility inventory, conducting site visits and inspections, and following up with education and enforcement actions. To choose which areas to investigate, the county developed a prioritization scheme based on the following factors:

  • Outfall size, used as a proxy for drainage area
  • Water quality monitoring data that identify hot spots for bacteria and other pollutants
  • History of complaints indicating frequent or continuous discharges
  • Generalized land use (focusing on commercial and industrial areas)
  • Number of hazardous waste-generating businesses and businesses on the Michigan's Critical Materials Register
  • Number of Priority I commercial/industrial facilities, which include automobile-related businesses/facilities and heavy manufacturing. Of lesser priority (priority II) are printers, dry cleaners/laundries, photo processors, utilities, paint stores, water conditioners, chemical laboratories, construction companies, and medium-light manufacturing. Priority III facilities include other industrial facilities, private service agencies, retail establishments, and schools.

Once geographic areas have been selected for investigation, a GIS-based (ArcViewTM) computer application uses North American Industrial Classification (NAIC) codes to classify businesses and scores subwatersheds or investigative areas by the number of priority I and II businesses. The application also creates a business list for a selected geographical area and coordinates these data with a tracking database.

During the site visit, a two-person crew conducts dye testing. One person drops a dye tablet into a plumbing fixture while the other observes a downstream portion of the sanitary sewer. If the dye is not observed, another dye tablet is deposited and the storm drain system or receiving water is monitored. If dye is detected in the storm drain system or receiving water, the inspectors notify the appropriate spill response and emergency management agencies. In addition, the crew inspects the exterior of the facility to identify evidence of spills, improperly stored materials, and other housekeeping issues that might result in discharges to a storm drain inlet.

Follow-up involves sending a thank you letter when no illicit connections or discharges are identified or, in a case where problems are found, sending a violation letter to the owner with a 30- to 90-day compliance date. If the business fails to comply, the local municipality (building inspector) is notified. If compliance is still not achieved, the case is referred to the Michigan Department of Environmental Quality. When a correction is confirmed, a thank you letter is sent to the owner and the file is closed. Wayne County has found that an education-based enforcement program conducted in partnership with local communities is very effective; in only two cases in the past 16 years has the County needed to refer an issue to the Michigan Department of Environmental Quality for enforcement.

Intergovernmental coordination has been important to the success of this program. The County has worked closely with the local community to obtain information (such as sewer maps), traffic control, local code enforcement, and site access, if needed. In some cases, community staff have been very involved; in other cases, communities have wanted only notification of a violation. The State also becomes involved when the County or a city does not achieve compliance. Because of this coordination, a multi-agency coordinated complaint response system is in place to address reports of discharges and spills.

Other aspects of the program that aid in preventing pollutants from entering the storm sewer system or receiving waters include a 24-hour hotline for reporting, emergency spill response, outfall inspections and surveys, failing onsite sewage disposal system investigations, and training in identifying and eliminating illicit discharges. All of these activities are coordinated with similar activities performed by local communities. For example, municipalities in the Rouge River watershed have implemented household hazardous waste disposal programs to provide additional protection against illegal dumping.

The original program was expanded to include residential areas where monitoring data indicated hot spots of high bacterial concentrations that were preventing a river from meeting water quality standards for recreational uses. Once initial sampling identified these hot spots, intensive follow-up sampling was conducted at outfalls and within the storm drain system until the source was isolated to one or two city blocks. At that point, the city visually inspected with closed-circuit television or smoke-tested the system or dye-tested homes and institutional facilities. In addition, the Health Department inspected septic systems in the hot spots for signs of failure.

In 1999 Wayne County developed an Illicit Discharge Elimination Plan Training Program designed to educate County and local community staff about illicit discharges and methods to find and eliminate them. This training program assists communities in preparing for their responsibilities under the NPDES Phase II Storm Water Rule for small municipal separate storm sewer systems. The training program consists of five modules: an overview, basic investigations, advanced investigations, construction-related illicit discharges, and combined basic/advanced investigations. Additionally, two specialty training sessions are offered, entitled "Recognizing and Reporting Illicit Discharges" and "Illicit Discharge Investigation Exercise." More than 1,000 people from across the nation have participated in Wayne County's training programs.

Additional Materials Related to this Case Study:

Additional Resources and Tools for this Minimum Control Measure

EPA presents this case study as an example to which Phase I and Phase II municipal stormwater programs can refer as they develop their own stormwater programs. Although EPA has reviewed the case studies, they should not be considered officially endorsed by the Agency and are not intended to represent full compliance with EPA’s stormwater Phase II minimum control measures. Each community must decide on the appropriate BMPs necessary to meet its unique permit requirements and local conditions.

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