Watershed Protection: Tracking, Eliminating Illegal Discharges

The Center for Watershed Protection has developed a manual that provides communities with guidance on establishing and implementing an Illicit Discharge Detection and Elimination (IDDE) program.

The Center for Watershed Protection has developed a manual that provides communities with guidance on establishing and implementing an Illicit Discharge Detection and Elimination (IDDE) program.

The manual incorporates the experience of more than 20 Phase 1 communities that were surveyed about their practices, levels of program effort, and lessons learned. These communities took many different approaches to solve the IDDE problem, and provided insights on common obstacles and setting realistic expectations.

Designed with a broad audience in mind, including agency heads, program managers, field technicians and water quality analysts, the manual is primarily focused on providing guidance for the thousands of Phase II communities that are now in the process of developing and implementing IDDE programs.

The report was written by Edward Brown and Deb Caraco of the Center for Watershed Protection and Robert Pitt of the University of Alabama at Tuscaloosa. It was produced as part of a cooperative agreement under the sponsorship of the US Environmental Protection Agency.

"Studies have shown that dry weather flows from storm drain systems may contribute a larger annual discharge mass for some pollutants than wet weather storm water flows," the authors wrote. "Detecting and eliminating these illicit discharges involves complex detective work, which makes it hard to establish a rigid prescription to hunt down and correct all illicit connections. Frequently, there is no single approach to take, but rather a variety of ways to get from detection to elimination.

"Local knowledge and available resources can play significant roles in determining which path to take. At the very least, communities need to systematically understand and characterize their stream, conveyance and storm sewer infrastructure systems."

The IDDE manual has been organized to address the broad range of administrative and technical considerations involved in setting up an effective program. In general, the manual gets progressively more complex and technical toward the end.

The first 10 chapters of the manual focus on the "big picture" considerations needed to successfully get an IDDE program off the ground. The final four chapters provide detailed technical information on the methods to screen, characterize and remove illicit discharges in MS4 communities. These chapters present the state-of-the-practice on specific monitoring techniques and protocols.

Information is provided to help users:
Define important terminology and understand key illicit discharge concepts.
Conduct an audit to understand community needs and capabilities.
Establish adequate legal authority.
Develop a tracking system to map outfalls and document reported illicit discharges.
Conduct desktop analyses to prioritize targets for illicit discharge control.
Conduct rapid reconnaissance of a stream corridor to find problem outfalls.
Apply new analytical and field methods to find and fix illicit discharges.
Educate municipal employees and the public to prevent discharges.
Estimate costs to run a program and conduct specific investigations.

Many of the IDDE methods presented in the manual were first developed and tested in Phase 1 communities. Specific techniques applied by those communities can be adapted to local conditions for Phase II community programs.

According to the authors, dry weather discharges are composed of one or more possible flow types, including sewage and septage from sewer pipes and septic systems; washwater from laundries, carwashes, etc.; tap water from leaks in the distribution system; landscape irrigation; and groundwater seepage into the stormwater system.

Water quality testing is used to identify flow types and distinguish between polluting and non-polluting flows. Each flow type has a distinct chemical fingerprint - but that fingerprint can differ regionally, the authors warned.

"In practice, many storm drain discharges represent a blend of several flow types, particularly at larger outfalls," the author wrote. "Chapter 12 of the manual presents several techniques to help isolate illicit discharges that are blended with cleaner discharges. Illicit discharges are also masked by higher volumes of stormwater runoff, making it difficult and frequently impossible to detect during wet weather periods."

At least 15 different indicator parameters can confirm the presence or origin of an illicit discharge. They include such indicators as ammonia, boron, chlorine, detergents, E.Coli, color, conductivity, fluoride, pH, etc.

Typical instrumentation for monitoring discharges include a spectrophotometer or colorimeter for ammonia, boron, chlorine, etc.; a multi-parameter probe for pH, conductivity, potassium, etc.; burette and stand or digital titrator for hardness; and a system like the Colilert Quanti-Tray for E.Coli.

Of course, when illicit discharges are identified, they need to be removed.

"The process is ongoing and the effectiveness of a program should improve with time," the authors wrote. "In fact, well-coordinated IDDE programs can benefit from and contribute to other community-wide water resources-based programs, such as public education, stormwater management, stream restoration and pollution prevention."

The guide includes several brief case studies highlighting what some utilities have done to control illegal discharges. Here are two examples:

Madison County, NC

In 1997, Madison County implemented a project to address straight piping problems. In 1999, a survey identified 205 households with black water straight-piping (toilet waste), 243 households with gray water straight piping (sink, shower, washer waste), and 104 households with failing septic systems. The project facilitated more than 10 community meetings and more than 20 educational articles on straight-piping and water quality in local papers. In addition, the project leverage $903,000 from the N.C. Clean Water Management Trust Fund to establish a Revolving Loan and Grant Program for low and moderate income county residents that needed assistance installing a septic system or repairing a failing one.

Wayne County, MI,

Wayne County has an active IDDE program that has included efforts to train all county field staff to identify and report suspicious discharges. The Illicit Discharge Elimination Training Program includes presentations for general field staff that instructs them in the identification and reporting of suspicious discharges. To date, 734 people from various agencies and communities throughout Michigan have attended the training sessions. The information these individuals gained from attending helped identify 82 illicit discharges in the counties of Oakland, Washtenaw and Wayne. Road division staff trained through the program discovered 12 septic systems in Wayne County that were failing or had direct discharges to surface water. Other counties found 70 illicit discharges during their investigations. The elimination of these discharges will prevent an estimated 3.5 million gallons of polluted water from reaching Michigan surface waters each year. Associated load reductions are estimated at 7,200 lbs/yr of BOD and 25,000 lbs/yr of TSS.

Editor's Note:
A free copy of "Illicit Discharge Detection and Elimination, A Guidance Manual for Program Development and Technical Assessments" can be downloaded in the PDF format at http://www.cwp.org/idde_verify.htm

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