BOA agenda 121018 - cancelled due to weather

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Standards TS-I or TS-II may be used on sites classified as Suitable or Provisionally Suitable for conventional, modified, alternative or innovative systems in accordance with 15A NCAC 18A .1900 et seq. The following modifications to siting criteria,vertical or horizontal separation distance requirements shall be acceptable: 1. Minimum initial vertical separation siting criteria and minimum vertical separation distances for trench bottoms specified in Rules.1955(m),.1956,and.1957 may be reduced for ground absorption systems r e c e i v i n g effluent from pretreatment systems meeting TS-I or TS-II as follows: •by a max i m um-QjC 25 percent for gravity dosed drainfields, and •by a maximum of 50 percent for pressure dosed drainfields(LPP or DRIP distribution), when all of the following conditions are met: a. the initial vertical separation siting criteria shall not be reduced to less than 12 inches from the soil surface to rock or any unsuitable soil horizon, b. the trench bottom vertical separation distance shall not be reduced to less than 12 inches to rock or tidal water, C. a Pressure-Dosed Sand Filter pretreatment system meeting Treatment Standard I1(TS-II)shall be used in conjunction with any reduction to any soil wetness_c_�dition in the initial vertical separation siting criteria or the trench bottom vertical separation distance, d. the site shall be evaluated by a Licensed Soil Scientist(see Section 1,below), e. with the exception of horizontal setback reductions from Drainage Systems,no other reductions in horizontal setbacks or increases in Long Term Acceptance Rates, as provided for in Sections DA and E.2, below, shall be used when any reductions in initial vertical separation siting criteria or trench bottom vertical separation distances are utilized. Furthermore, no reduction in trench bottom area shall be allowed for chambered or polystyrene aggregate systems when any of these reductions are utilized. These reductions are also not applicable to a PPSPS system sized in accordance with Rule.1956(3)(a)(ii),and f. whenever any of the above reductions in initial vertical separation criteria or trench bottom vertical separation distances are utilized,the property line minimum horizontal setback distance shall be increased to 25 feet. 2. Drainage Systems: When a Pressure-Dosed Sand Filter pretreatment system meeting TS-I or TS-1I is to be utilized, drainage may by used on sites with Group III Soil Texture, and soils with Provisionally Suitable (or Suitable) structure are allowed within the vertical separation zone. A groundwater lowering system may also be used to meet the siting criteria or vertical separation requirements for soil wetness conditions for fill systems specified in Rule .1957(b)(1). Site evaluation by a Licensed Soil Scientist shall be required, and the drainage system shall be designed by a person with demonstrated knowledge of drainage systems(see Section 1,below). 3. Saprolite Systems: When a Pressure-Dosed Sand Filter pretreatment system meeting TS-I or TS-I1 is to be utilized,saprolite with sandy clay loam texture may be used. The maximum LTAR for sandy clay loam saprolite texture shall be 0.2 gpd/ft' for conventional trenches and 0.10 gpd/ft for LPP trenches. Nitrification trenches in saprolite may be installed up to five feet deep. Site evaluation by a Licensed Sail Scientist or Professional Geologist shall be required(see Section I,below). 4. Minimum horizontal setbacks shall be as specified in Rule.1950,except as provided for in Table 1. Table 1. Minimum horizontal setbacks for ground absorption systems when Pressure-Dosed Sand Filter Pretreatment Systems meeting TS-1 or TS-lI are used.' 3 131