Adaptive Management of a CSO Control Plan Provides More Benefits

Combined sewer overflow (CSO) control planning often ends with a negotiated legal document (either an administrative order or a consent decree) issued by the federal or state government. Sometimes these documents can be fairly prescriptive in their language regarding the interim goals, objectives, and milestones that need to be achieved during the implementation of the CSO abatement program. Compliance text that is too restrictive could limit the type of collective, interactive, and adaptive management of a CSO program that would actually benefit both the regulatory agencies and the CSO community. Using an adaptive management approach to the implementation of a long-term and dynamic CSO control plan provides more benefits.The Lowell Regional Wastewater Utility (LRWWU) operates a large combined sewer collection and treatment system (CSS) in Massachusetts. In February 2002, the utility submitted its long-term CSO control plan (LTCP). The LTCP identified a phased program of improvements that was developed with the intent that the city assess its ongoing implementation of the Phase I program to identify the benefits and determine where additional work would be cost-effective. On June 16, 2003, the city received an administrative order from the U.S. Environmental Protection Agency that presented a compliance schedule for the city to implement this phased approach and to proceed with the Phase I LTCP. To date, the city is completing its final Phase I requirements and has achieved significant CSO reduction. The flexible, adaptive management approach taken by the city has allowed it to incorporate new CSO control opportunities and address several unanticipated operational issues and spending requirements without deviating from its CSO control objectives. Based on this success, the city has proposed (and received approval) for a new Phase IA LTCP program that continues the city's CSO abatement plan.