SECTION 252:616-7-3. Compacted clay liners

(a)   Suitability. A clay liner, of native or imported clay soils compacted in lifts, is a moderately protective liner system, appropriate for compatible Class II, III and V wastewaters.

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

(1)   soil classification name(s) for all soils used to construct the surface impoundment and a list of source(s) of any imported soil;

(2)   particle size distribution, Atterberg limits, and shrink/swell potential, according to ASTM test methods;

(3)   compaction curves indicating the moisture/density relationship with saturated hydraulic conductivity for a practical range of density and moisture values;

(4)   optimum moisture content of the soil at various compaction densities; and

(5)   saturated hydraulic conductivity of a representative compacted sample using water and actual or synthetic wastewater.

(c)   Construction requirements. Construct a compacted-clay liner system:

(1)   with a water content-density range to assure a maximum saturated hydraulic conductivity of 1 x 10^-7cm/sec, verified by an independent soil testing laboratory;

(2)   in lifts that are not more than nine inches thick uncompacted, and six inches thick compacted. Examine each lift before compaction and remove rocks, debris, or foreign matter greater than one inch in diameter. Also remove and repair lenses, cracks, channels and root holes that could adversely affect hydraulic conductivity;

(3)   with bottom seal and dike cores relatively incompressible and compacted at a water content up to 4 percent above the optimum and to at least 90% Standard Proctor Density.

(4)   by scarring the soils between lifts for good bonding;

(5)   by performing two tests per lift to monitor the lift thickness, the water content, the compaction density and the saturated hydraulic conductivity of the liner;

(6)   with at least two feet thick with at least four lifts. Depending on the wastewater class, impoundment purpose, groundwater depth, and other criteria, the DEQ may require a thicker liner.

(7)   by protecting the soil liner from cracking during and after construction due to desiccation or freezing, and document the procedures; and

(8)   by protecting the liner with at least 12 inches of soil.

[Source: Added at 17 Ok Reg 1925, eff 6-12-00]