SECTION 252:616-7-4. Synthetic liners

(a)   Suitability. A liner system constructed using a soil subbase, a specially prepared subgrade, a synthetic liner, and a protective soil cover can be considered a highly protective liner system and may be appropriate for Class I, II, III or V wastewater and may be required for certain wastewater.

(b)   Pre-construction requirements. Before construction, classify and test all liner material and submit the following with the industrial wastewater treatment permit application:

(1)   design specifications with suitable physical properties of the liner material for percent elongation, strength tests (tensile, tear, breaking, shear, and bonded seam), hydrostatic resistance, percent volatile losses, and reactions to water (absorption and extraction);

(2)   design specifications with suitable chemical properties of the liner material for chemical resistance to wastewater, ultraviolet light resistance, and protection against biological decay;

(3)   show the liner will maintain physical properties under all prolonged and varying conditions expected at the facility, included but not limited to, temperature variation, UV radiation, biological attack, and waste or wastewater composition; and

(4)   show the liner will perform as a physical barrier to waste and wastewater seepage into groundwater.

(c)   Construction requirements. Construct a synthetic liner system by:

(1)   protecting the liner membrane from physical damage by a specially prepared bedding material free of rocks, roots, debris, sharp objects, or foreign matter of a size or shape that could damage the liner;

(2)   preventing settlement or stability problems of the subgrade under maximum operational conditions. Vent the subgrade with perforated pipe to reduce gas and hydrostatic pressure;

(3)   inspecting each roll of liner material in the field before and during placement by a manufacturer-qualified inspector to meet manufacturer specifications against leaks;

(4)   installing liners using commonly accepted industry techniques and practices for bedding and subgrade preparation, anchor trenches of 6-inch minimum depth and placement 9 to 12 inches beyond the dike slope break, synthetic liner installation and seaming, and field QA/QC inspections and seam testing;

(5)   inspecting seams visually and conduct pressure tests, vacuum tests or other non-destructive seam tests to monitor the effectiveness of personnel and equipment;

(6)   maintaining side-slope stability. Exterior side slopes shall be a minimum of 2:1 (horizontal to vertical distance). Internal side slopes shall be between 2.5:1 and 4:1. Use the interfacial friction angle between the soil and the liner material to determine the maximum side-slope angle. All side-slope angles shall be less than the interfacial friction angle; and

(7)   taking adequate measures to protect the integrity of the liner. On dike slopes, backfill should consist of at least a 3-inch layer of sand or finely textured soil and covered with at least a 3-inch layer of heavier cobble, coarse gravel, or small riprap.

[Source: Added at 17 Ok Reg 1925, eff 6-12-00; Amended at 30 Ok Reg 1087, eff 7-1-13]