FIGURE 4-6 Sanitary sewer overflow from an elevated manhole in the Pittsburgh. region. SOURCE: Photograph courtesy of 3RWW.

was found (WRAS, 2003d). The Stonycreek River and Little Conemaugh River watersheds report a PENNVEST project in 1998 to Windber Borough to eliminate backup of sewage into basements during wet weather and to replace collection lines. Additional sanitary sewer projects in this watershed were also undertaken.

Individual on-lot septic systems (more accurately referred to as on-site sewage treatment and disposal systems) are frequent alternatives to wastewater treatment plants in sparsely populated areas of the country where the costs of constructing centralized treatment systems are prohibitive. If properly sited and functioning, OSTDSs can receive, treat, and dispose of wastes in a manner that is comparable to wastewater treated in a central facility (EPA, 1980, 1997, 2002c). Table 4-12 provides some ranges for typical contaminants from septic tank effluent and from downgradient in the leach field. Both the tank and the leachfield must operate properly for treatment to be complete. OSTDSs can be designed to provide waste treatment from a single house, business, or groups of structures. The 1997 Response to Congress on Use of Decentralized Wastewater Treatment Systems⁹ states that “adequately managed decentralized wastewater systems are a cost-effective and long-term option for meeting public health and water quality goals” (EPA, 1997).