b) Standards for the low permeability layer:

1. 1) Construction of a low permeability layer shall begin not later than 60 days after placement of the final lift of solid waste.
2. 2) The low permeability layer shall cover the entire unit and connect with the liner system.

3. 3) The low permeability layer shall consist of any one of the following:

   1. A) A compacted earth layer constructed in accordance with the following standards:

      1. i) The minimum allowable thickness shall be 0.61 meters (2.0 feet).
      2. ii) The layer shall be compacted to achieve a permeability of 1x(10^-7) centimeters per second and minimize void spaces.
      3. iii) Alternative specifications may be utilized provided that the performance of the low permeability layer is equal to or superior to the performance of a layer meeting the requirements of subsections (b)(3)(A)(i) and (b)(3)(A)(ii) above.

   2. B) A geomembrane constructed in accordance with the following standards:

      1. i) The geomembrane shall provide performance equal or superior to the compacted earth layer described in subsection (b)(3)(A) above.
      2. ii) The geomembrane shall have strength to withstand the normal stresses imposed by the waste stabilization process.
      3. iii) The geomembrane shall be placed over a prepared base free from sharp objects and other materials which may cause damage.
   3. C) Any other low permeability layer construction techniques or materials, provided that they provide equivalent or superior performance to the requirements of this subsection.

c) Standards for the final protective layer:

1. 1) The final protective layer shall cover the entire low permeability layer.
2. 2) The thickness of the final protective layer shall be sufficient to protect the low permeability layer from freezing and minimize root penetration of the low permeability layer, but shall not be less than 0.46 meter (1.5 feet).
3. 3) The final protective layer shall consist of soil material capable of supporting vegetation.
4. 4) The final protective layer shall be placed as soon as possible after placement of the low permeability layer to prevent desiccation, cracking, freezing or other damage to the low permeability layer.