United States Environmental Protection Agency August 1993 832-F-93-003 Office of Water WH547 &EPA Combined Sewer Overflows In Your Community ------- WHAT I COMBINED SEWER OVERFLOW (CSO)? Some cities collect both rainwater run- off and sanitary wastewater in the same sewer. These are called "combined sewers/' Sometimes when it rains, combined sewers do not have enough capacity to carry all the rainwater and wastewater or the treatment plant is not large enough to treat the combined flow. Jn these situations, the combined wastewater overflows untreated into the nearest body of water—streams, lakes, rivers, or estuaries, creating a com- bined sewer overflow (CSO). ------- ONTROLLING CSO VERY IMPORTAN "CSO controls protect your community's public health and its environment. For more information on CSO strategy, policy and guidance, you can contact the U.S. EPA Water Management Division in your Region or the National Small Flows Clearinghouse, P.O. Box 6064, Morgantown, West Virginia (Toll Free: 1-800-624-8301). U.S. EPA Region I (CT, ME, MA, NH, HI, VT) JFK Federal Building Boston, MA 02203 (617) 565-3478 U.S. EPA Region II (NJ, NY, PR, VI) 26 Federal Plaza New York, NY 10278 (212) 264-2513 U.S. EPA Region VI (AR, LA, TX, OK, NM) 1445 Ross Ave., Suite 1200 Dallas, TX 75202-2733 (214) 655-7101 U.S. EPA Region VII (IA, KS, MO, NE) 726 Minnesota Avenue Kansas City, KS 66101 (913) 551-7030 U.S. EPA Region III U.S. EPA Region VIII (DE, MD, PA, VA, WV, DC) (CO, UT, WY, MT, ND, SD) 841 Chestnut Building 999 18th St., Suite 500 Philadelphia, PA 19107 Denver, CO 80202 (215)597-9410 (303)293-1542 U.S. EPA Region IV (AL, GA, R, MS, NC, SC, TN, KY) 345 Courtland St., NE Atlanta, GA 30365 (404) 347-4450 U.S. EPA Region V (IL, IN, OH, MI, MN, WI) 77 W. Jackson Blvd. Chicago, IL 60604 (312) 353-2145 U.S. EPA Region I (AZ, CA, GU, HI, NV, 75 Hawthorne Stree San Francisco, CA 9 (415) 744-2125 i U.S. EPA Region X (AK, ID, OR, WA) 1200 Sixth Avenue Seattle, WA 98101 (206) 553-1793 ------- NTROLLE The Clean Water Act requires the U.S. EPA and States to issue permits for controlling discharges from CSOs. The permit- tees are responsible for implementing a series of minimum CSO controls and, if necessary, developing and implement- ing a long-term CSO control plan. The minimum CSO controls basically require communities to (1) fully utilize the existing capacity of wastewater collec- tion and treatment systems through changes in operational practices, (2) prevent pollutants from entering the com- bined sewers, and (3) install simple devices to remove solids and floatable materials from the CSOs. In some communi- ties, the minimum controls may be adequate to achieve water quality standards. Instull bur screens at CSO locations. Change operational practices. When the CSOs are causing serious water pollu- tion, communities will need to take additional actions. They will need to develop and imple- ment long-term CSO control plans. These control plans require the identification, evaluation, and implementation of various CSO control strategies to achieve water quality stan- dards by the communities. The U.S. EPA, State environmental agencies, water quality groups, and communities should work together to com- plete the long-term CSO control plans. ------- LONG-TERM CSO PLANS MAY INCLUDE CONTROLS LIKE: Separating storm waters from sanitary wastewaters. Using basins or tunnels to store the combined wastewater until the treatment plant can handle it. HOW EXPENSIVE ARE CSO CONTROL MEASURES? The costs of CSO controls may be high in some communities, but low in others. The severity and frequency of the CSOs plus the local water quality standards will determine the types of CSO controls and their costs. Even though the actual CSO control costs are un- known for many communities, the U.S. EPA and State agencies will work with the CSO communities to find economically achievable solutions that will improve public health and create a safer environ- ment for everyone. ------- WHERE ARE THE CSOS? Combined sewers serve about 43,000,000 people in an estimated 1,100 communities. Most of the CSO communities are located in the Northeast and Great Lakes regions. More than three-quarters of the communi- ties are located in only 11 states. HOW CSOS AFFECT YOU AND YOUR COMMUNITY Community control ofCSOs is essential to presetting the public health and the ecological balance of our streams, rivers, lakes, and oceans. During dry weather, combined sewers carry the community's wastewaters to the treat- ment facilities. When it rains, however, and CSOs occur, your health and environment may be threatened by the untreated waste- water that is discharged from the combined sewers to your community's rivers, lakes, streams, oceans, estuaries, and wetlands. The main pollutants in CSOs are untreated human and industrial wastes, toxic materi- als like oil and pesticides, and floating debris washed into the sewer system. These pollutants can affect your health when you swim in CSO-polluted water or when you eat fish or shellfish contaminated by the CSOs. The pollutants in CSOs can cause a variety of diseases, ranging from dysentery to hepatitis. CSO pollutants ar not just a human health concern. They can damage the environment for fish, shellfish, and other aquatic life I ------- |