Option Application Schedule Typical Rate (mt/ha)
Agricultural Annual 10
Forest One time, or at 3- to 5-year intervals 45
Reclamation One time 100
Source: USEPA, Process Design Manual: Land Application of Municipal Sludge, EPA 625/1-83-016, CERI, U.S. Environmental Protection Agency, Cincinnati, OH, 1983.
content. When the amount of sludge to be managed has been estimated, it is necessary to conduct a map survey, as described in Chapter 2, to identify sites with potential feasibility for agriculture, forests, reclamation, or surface treatment. Table 9.15 presents preliminary loading rates for the four application options. These values should be used only for this preliminary screening and not for design. A guide to field storage of biosolids and organic by-products to be used in agriculture and soil management has been prepared by the USEPA and the USDA (2000). Water quality and control of pathogens are discussed.
The land area estimates produced with the values in Table 9.15 are the treatment area only, with no allowance for sludge storage, buffer zones, and other requirements. The preliminary screening to identify suitable sites can be a desktop analysis using commonly available information. Numerical rating procedures based on soil and groundwater conditions, slopes, existing land use, flood potential, and economic factors were described in Chapter 2 and in Reed and Crites (1984) and USEPA (1978, 1983). These procedures should be used to identify the most desirable sites if a choice exists. This preliminary screening is advised because it is very costly to conduct detailed field investigations on every potential site. The final site selection is based on the technical data obtained by the site investigation, on a cost-effectiveness evaluation of capital and operating costs, and on the social acceptability of both the site and the intended sludge management option. The requirements for pathogen reduction were discussed in Chapter 3, and details can be obtained by consulting 40 CFR Part 503 (Federal Register, February 19, 1993) (Bastian, 1993; Crites et al., 2000).
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