(a) Geosynthetic drainage layers must comply with the following:

1. (1) Any geosynthetic drainage layers designed for use in a groundwater suppression system or a leachate collection and removal system must meet the structural and hydraulic transmissivity design requirements using actual boundary conditions at the maximum adjusted design load for a minimum period of 100 hours, modified to take into consideration the long-term conditions for creep representative of site conditions, and other reduction factors.

   1. (i) For hydraulic flow capacity calculations, the design engineer must use a factor of safety of at least three, and consider the reduction in transmissivity due to creep, biological clogging, and chemical clogging.
   2. (ii) The chemical and physical resistance of the geosynthetic drainage material must be adequate so that its hydraulic transmissivity is not adversely affected by waste placement or leachate.

2. (2) Any geosynthetic drainage layers designed for use in a final cover system for either drainage or gas venting must meet the transmissivity design requirements using actual boundary conditions at the maximum adjusted design load for a minimum period of 100 hours, and appropriate reduction factors and must consider any proposed landfill end use structures.

   1. (i) For hydraulic flow capacity calculations, the design engineer must use a factor safety of at least three.

   2. (ii) The hydraulic design of the geosynthetic drainage layer should be performed using the saturated hydraulic conductivity of the barrier protection layer.

      (b) Construction requirements.

3. (1) Geosynthetic drainage layers must not be seamed or fastened horizontally more than once per length of side slope. If horizontal seams are necessary, they must be staggered between adjacent rolls. The geosynthetic drainage layers must be seamed or fastened together in accordance with industry standards.
4. (2) The geosynthetic drainage layer must be installed in accordance with the procedures set forth in section 363-6.8(b)(2)-(4) and (5)(iii) of this Subpart.
5. (3) If a geosynthetic drainage layer is specified in the primary leachate collection and removal system, a 24-inch soil drainage layer is required which meets the minimum requirements of section 363-6.10 of this Subpart.

6. (4) If a geosynthetic drainage layer is specified in the secondary leachate collection and removal system, a 12-inch soil drainage layer which meets the requirements of section 363-6.10 of this Subpart is required in all areas where the liner slope is less than 10 percent.

   (c) Certification requirements.

   The project engineer must certify the following information as part of certification:

7. (1) results of applicable geosynthetic quality control testing required in paragraph 363-6.8(c)(1) of this Subpart;
8. (2) results of hydraulic transmissivity testing performed in a laboratory in accordance with subdivision (a) of this section including confirmation that the head within the leachate collection and removal layer will remain less than the thickness of that layer for the design flow of 1,000 gallons per acre per day in the secondary leachate collection and removal system is met;
9. (3) that the construction quality assurance staff have performed visual inspections for any depressions or irregularities on all installed products;
10. (4) that post-construction care procedures were carried out to protect the geosynthetic drainage layer from the intrusion of fines related to water-borne and wind-borne sedimentation.