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<br />City of San Marcos <br /> <br />TPDES Permit No. WQOOl0273002 <br /> <br />TABLE 1 <br /> <br />Ceiling Concentration <br />(milligrams per kilogram)* <br /> <br />Pollutant <br /> <br />Arsenic <br />Cadmium <br />Clrromium <br />Copper <br />Lead <br />Mercury <br />Molybdenum <br />Nickel <br />PCBs <br />Selenium <br />Zinc <br /> <br />75 <br />85 <br />3000 <br />4300 <br />840 <br />57 <br />75 <br />420 <br />49 <br />100 <br />7500 <br /> <br />* Dry weight basis <br /> <br />3. Pathogen Control <br /> <br />All sewage sludge that is applied to agricultural land, forest, a public contact site, or a reclamation site shall be treated by one <br />of the following methods to ensure that the sludge meets either the Class A or Class B pathogen requirements. <br /> <br />a. Six alternatives are available to demonstrate compliance with Class A sewage sludge. The first 4 options require <br />either the density of fecal coliform in the sewage sludge be less than 1000 Most Probable Number (MPN) per gram <br />of total solids (dry weight basis), or the density of Salmonella sp. bacteria in the sewage sludge be less than three <br />MPN per four grams of total solids (dry weight basis) at the time the sewage sludge is used or disposed. Below are <br />the additional requirements necessary to meet the defInition of a Class A sludge. <br /> <br />Alternative 1 - The temperature of the sewage sludge that is used or disposed shall be maintained at OT above a <br />specific value for a period of time. See 30 TAC Section 312.82(a)(2)(A) for specific information. <br /> <br />Alternative 2 - The pH of the sewage sludge that is used or disposed shall be raised to above 12 std. units and shall <br />remain above 12 std. units for 72 hours. <br /> <br />The temperature of the sewage sludge shall be above 52 degrees Celsius for 12 hours or longer during the period <br />that the pH of the sewage sludge is above 12 std. units. <br /> <br />At the end of the 72-hour period during which the pH of the sewage sludge is above 12 std. units, the sewage sludge <br />shall be air dried to achieve a percent solids in the sewage sludge greater than 50 percent. <br /> <br />Alternative 3 - The sewage sludge shall be analyzed for enteric viruses prior to pathogen treatment. The limit for <br />enteric viruses is less than one Plaque- fonning Unit per four grams of total solids (dry weight basis) either before <br />or following pathogen treatment. See 30 TAC Section 312.82(a)(2)(C)(i-iii) for specifIc information. The sewage <br />sludge shall be analyzed for viable helminth ova prior to pathogen treatment. The limit for viable helminth ova is <br />less than one per four grams of total solids (dry weight basis) either before or following pathogen treatment. See <br />30 TAC Section 312.82(a)(2)(C)(iv-vi) for specific information. <br /> <br />Alternative 4 - The density of enteric viruses in the sewage sludge shall be less than one Plaque-forming Unit per <br />four grams of total solids (dry weight basis) at the time the sewage sludge is used or disposed. The density of viable <br />helminth ova in the sewage sludge shall be less than one per four grams of total solids (dry weight basis) at the time <br />the sewage sludge is used or disposed. <br /> <br />Alternative 5 (PFRP) - Sewage sludge that is used or disposed of shall be treated in one of the processes to Further <br />Reduce Pathogens (PFRP) described in 40 CFR Part 503, Appendix B. PFRP include composting, heat drying, heat <br />treatment, and thermophilic aerobic digestion. <br /> <br />Alternative 6 (PFRP Equivalent) - Sewage sludge that is used or disposed of shall be treated in a process that has <br />been approved by the U. S. Environmental Protection Agency as being equivalent to those in Alternative 5. <br /> <br />Page 13 <br />