Section 329IAC10-17-13. Optional drainage layer filter; design requirements

   A filter fabric may be incorporated into the drainage layer design to prevent fine soil particles of the protective soil cover from migrating into the drainage medium. The design of the filter must allow gases and water to freely enter the drainage medium and must provide the following:

(1) Adequate permeability, such that k_f ≥ 10k_s, where:

(A) k_f = the geotextile filter permeability; and

(B) k_s = the overlying protective cover soil permeability.

(2) Soil particle retention that meets the following criteria, or an equivalent criteria:

(A) O₉₅ of the geotextile < (2) d₈₅ of the protective cover.

(B) O₉₅ of the geotextile > (2) d₁₅ of the protective cover, where:

(i) O₉₅ = the apparent opening size of the geotextile at which ninety-five percent (95%) of the soil particles will be retained;

(ii) d₈₅ = the protective cover soil particle size at which eighty-five percent (85%) of the particles are finer; and

(iii) d₁₅ = the protective cover soil particle size at which fifteen percent (15%) of the particles are finer.

(3) Adequate construction survivability, with construction survivability assessed using accepted industry testing standards, which take into account:

(A) the severity of installation, with consideration of the type of material placed adjacent to the geotextile;

(B) the construction installation technique; and

(C) the minimum strength properties prescribed by applicable industry guidelines with consideration of the severity of the installation.

(4) Adequate chemical and physical resistance to:

(A) the expected waste;

(B) the overlying materials; and

(C) the leachate expected to be generated at the MSWLF.

(5) Any additional requirements necessary to obtain an adequate filter as specified in the construction plans or as determined by the commissioner.

(Solid Waste Management Division; 329 IAC 10-17-13; filed Mar 14, 1996, 5:00 p.m.: 19 IR 1839; filed Aug 2, 1999, 11:50 a.m.: 22 IR 3819)