. "5 Water Quality Improvement: Decision-Making Strategies and Technical Solutions." Regional Cooperation for Water Quality Improvement in Southwestern Pennsylvania. Washington, DC: The National Academies Press, 2005.
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Regional Cooperation for Water Quality Improvement in Southwestern Pennsylvania
TABLE 5-7 Comparison of Consent Order Versus CMOM Requirements for 83 Communities Serviced by ALCOSAN
Basic CMOM Requirements
Consent Order Requirements
1. More prescriptive characterization of collection system requiring detailed maps and extensive record keeping
1. Hire an engineer to prepare a sewer investigation plan
2. Televising of collection system includes 180 specific questions
2. Inspect the collection system through physical surveys and TV cameras; conduct dye testing of roof leaders, driveway drains, springs, and catch basins
3. Asset management program ties value of aging infrastructures and long-term repair costs
3. Write ordinances and develop enforcement program to eliminate illegal laterals; develop a plan to determine capacity and remediate the problems in the collection system
4. Requirements of program tied to NPDES permits
4. Implement the plan and coordinate with ALCOSAN and the 83 communities
5. Completion dates more long-term and comprehensive
5. Completion dates not less than 5 years
As noted in the previous section, the second part of consent orders directed local governments to continue to implement the nine minimum controls required under EPA’s CSO policy. Several of these measures are directed toward reducing stormwater flows entering collection systems. As for CMOM, the committee recommends that similar actions be undertaken by all other municipalities that contribute sanitary sewer flows to the ALCOSAN system.
These measures might also include a wide range of alternative technologies, including urban retrofitting, low-impact developments, and recently considered ecological techniques that may offer potential stormwater flow reductions and are being tested in other communities.
3. Segregation of Combined Sewer Flows into Separate Sewers. In some portions of the combined sewer systems, it may be cost-effective to separate stormwater from sanitary sewage by constructing parallel collection systems. In some instances, construction of separate sanitary sewers may be appropriate. Segregated stormwater could then be treated and discharged through decentralized treatment systems, including wet and dry detention basins and other technologies discussed in later sections of this chapter. In some cases, the quality of stormwater runoff may be sufficient to allow rerouting of segregated stormwater through open channels with direct discharge to streams.
4. Real-Time Control of Combined and Separate Sewers. The use of RTC of flows in separate sanitary and combined sewers and stormwater conveyance systems should be investigated and evaluated as a means to reduce peak loading on centralized and decentralized treatment systems. The October 2003 consent orders required affected municipalities to install