1. (a) Sewage sludge shall not be placed on an active sludge unit if it is likely to adversely affect a threatened or endangered species listed under the Endangered Species Act, §4, or its designated critical habitat.
2. (b) An active sludge unit shall not restrict the flow of the 100-year flood nor be located within the 100-year floodway.
3. (c) When a surface disposal site is located in a seismic impact zone, each sludge unit in that site shall be designed to withstand the maximum recorded horizontal ground-level acceleration.
4. (d) An active sludge unit shall be located 60 meters or more from a fault that has displacement in Holocene time, unless otherwise approved by the commission.
5. (e) An active sludge unit shall not be located in an unstable area.
6. (f) An active sludge unit shall not be located in a wetland except as provided in permit issued under the Clean Water Act, §402 or §404.
7. (g) Runoff from an active sludge unit shall be collected and disposed in accordance with discharge permit requirements and any other applicable requirements. The runoff collection system for an active sludge unit shall have the capacity to handle runoff from a 25-year, 24-hour rainfall event.
8. (h) The leachate collection system for an active sludge unit that has a liner and leachate collection system shall be operated and maintained during the period the sludge unit is active and for three years after the sludge unit closes.
9. (i) Leachate from an active sludge unit that has a liner and leachate collection system shall be collected and disposed in accordance with the applicable requirements during the period the sludge unit is active and for three years after the sludge unit closes.
10. (j) When a cover is placed on an active sewage sludge unit, the concentration of methane gas in air in any structure within the surface disposal site shall not exceed 25% of the lower explosive limit for methane gas during the period that the sewage sludge unit is active and the concentration of methane gas in air at the property line of the surface disposal site shall not exceed the lower explosive limit for methane gas during the period that the sludge unit is active. When a final cover is placed on a sludge unit at closure, the concentration of methane gas in air in any structure within the surface disposal site shall not exceed 25% of the lower explosive limit for methane gas for three years after the sludge unit closes and the concentration of methane gas in air at the property line of the surface disposal site shall not exceed the lower explosive limit for methane gas for three years after the sludge unit closes. On a case by case basis, the executive director may consider exclusion from these requirements.
11. (k) A food crop, a feed crop, or a fiber crop shall not be grown on an active sludge unit, unless the owner/operator of the surface disposal site demonstrates to the commission that through additional management practices, public health and the environment are protected from any reasonably anticipated adverse effects of metals in sewage sludge when crops are grown.
12. (l) Animals shall not be grazed on an active sludge unit, unless the owner/operator of the surface disposal site demonstrates to the commission that through additional management practices, public health and the environment are protected from any reasonably anticipated adverse effects of metals in sewage sludge when animals are grazed.

13. (m) Public access to a surface disposal site shall be restricted during the period that the surface disposal site contains an active sludge unit and for a period of three years after the last active sludge unit in the surface disposal site closes. The means of restricting access to a surface disposal site shall be effective with consideration of the location of the site and adjacent land use(s).

    1. (1) The permit application shall include an explanation of the means for restricting access to a surface disposal site.
    2. (2) The executive director shall include, as a condition of the proposed permit, specific requirements for the means of restricting access to a surface disposal site.
14. (n) Sewage sludge placed on an active sludge unit must not contaminate an aquifer. Results of a groundwater monitoring program developed by a licensed professional geoscientist or licensed professional engineer or a certification by a licensed professional geoscientist or licensed professional engineer shall be used to demonstrate that sewage sludge placed on an active sludge unit does not contaminate an aquifer. The results or certification shall be signed, sealed, and dated by the licensed professional geoscientist or licensed professional engineer preparing the results or certification.

Source Note:The provisions of this §312.64 adopted to be effective October 13, 1995, 20 TexReg 7840; amended to be effective September 1, 2003, 28 TexReg 6300.