EPA Proposes Post-Construction Guidance For Monitoring Combined Sewer Overflows

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The Environmental Protection Agency issued proposed guidance Aug. 9 to help municipal and state water officials determine the effectiveness of post-construction, long-term plans for monitoring and controlling combined sewer overflows.

The document, CSO Post Construction Compliance Monitoring Guidance, was released on the EPA website.

Comments are being sought until Sept. 30, and EPA said it is particularly interested in how the guidance might help small communities in their planning.

According to EPA, the goal of combined sewer overflow (CSO) post-construction monitoring is to evaluate whether the level of control proposed in long-term compliance plans—including proposed water quality goals—has been achieved.

Post-construction monitoring helps in adjusting CSO controls based on data collected during implementation phases of the CSO long-term control plan, the agency said in the proposed guidance.

Combined sewer systems are designed to collect rainwater runoff, sewage, and industrial waste in the same pipe. CSOs pose a major water pollution concern for the approximately 770 cities that have combined sewer systems, according to EPA.

CSO Policy Issued in 1994

The combined sewer overflow policy, issued April 11, 1994, under the Clean Water Act, established a national framework under the National Pollutant Discharge Elimination System permit program for controlling discharges into the nation's waters from combined sewer systems. One provision was that regulated communities would develop comprehensive CSO control measures, including controls based on long-term plans (59 Fed. Reg. 18,688).

“The post-construction compliance monitoring is a continuous process to determine whether the CSO [long-term control plan] is meeting the regulatory requirements as planned,” the proposed guidance said.

The 1994 policy includes nine controls. The ninth, and the subject of the proposed guidance, is development of a post-construction compliance monitoring program sufficient to verify compliance with water quality requirements and to ascertain the effectiveness of CSOs, the agency said.

The policy defines expectations for regulated communities and state water authorities addressing water quality standards and NPDES permits.

Communities Developing Plans

Many communities served by combined sewer systems have developed and are implementing long-term control plans “or about to take the next step of implementing a post-construction compliance monitoring program,” James Hanlon, director of EPA's Office of Wastewater Management, said in a memorandum contained in the proposed guidance.

The proposed guidance stresses the importance of continuously updating and evaluating data to ensure its quality. While post-construction monitoring programs should build on previous collected data, they also should provide followup data to determine whether controls that have been put in place have met their objectives and whether the permittee is complying with water quality-based effluent limits in its NPDES permits, the proposed guidance said.

“Because this information will ultimately be used to verify compliance with water quality-based requirements, reducing data uncertainty should be a high priority,” it said.

If data analysis indicates a community cannot meet water quality standards because it is financially or technologically infeasible, the community “should develop a schedule for incremental improvements and then revisit additional controls as financial conditions change or as new control technologies emerge,” the document said.

Planning Documents to be Considered

The proposed guidance gives examples of planning documents that permittees should consider in preparing for post-construction monitoring. These include quality assurance project plans, plans for assessing CSO controls, field sampling plans, and standard operating procedures.

The agency said that while it recognizes it is often difficult to document the direct relationship between individual CSO controls and specific improvements in water quality, “the comparison of long-term quality trends before and after implementing the [long-term control plan], if the data are available, can provide a correlation between CSO controls and improvements in water quality if other things stay the same.”

Alexandra Dunn, executive director of the Association of State and Interstate Water Pollution Control Administrators, told BNA, “We're pleased that EPA has put out a guidance that can assist us with determining that water quality improvements have been made. … The document will help implement post-construction monitoring programs—a requirement in the CSO policy.”

Many municipal long-term plans have been required by legal agreements, with some taking more than a decade to implement, Dunn said.

Nathan Gardner-Andrews, general counsel for the National Association of Clean Water Agencies, told BNA Aug. 10 that NACWA has not yet evaluated the proposed guidance, but plans to submit comments.

By Linda Roeder

EPA's proposed CSO Post Construction Compliance Monitoring Guidanceis available at http://www.epa.gov/npdes/pubs/final_draft_cso_pccm_guidance.pdf .