Section 213.11. Specific liner specifications.

 

(1)   Natural soil liner specifications.

(a) Natural soil liners shall consist of soils of which a minimum of 50% of the soil particles pass a No. 200 sieve.

(b) Natural soil to be used as a liner shall contain less than 2% organic material, and less than 5% by weight of the natural soil to be used shall be retained on a No. 4 sieve.

(c) Natural soil to be used as a liner shall have a plasticity index of at least 15.

(d) Natural soil liners shall be compacted to at least 95% of the maximum standard proctor dry density.

(e) Natural soil liners shall be constructed and compacted in lifts. A lift may not exceed a compacted thickness of 6 inches.

(f) Frost susceptible soils may not be used to construct a natural soil liner. Silts and silty sands shall be considered frost susceptible.

(g) When constructing natural soil liners with native in-place soils, the subbase shall be scarified prior to compaction. Subsequently, the existing base shall be scarified prior to placement of each successive lift.

(h) Natural soil liners shall be constructed under the direct supervision of a qualified soils technician or engineer, or geotechnical engineer.

(2)   Soil-bentonite liners.

(a) The soil to be mixed with the bentonite shall have a plasticity index of at least 12, a minimum of 30% of the soil by weight shall pass a No. 200 sieve, and less than 5% by weight shall be retained on a No. 4 sieve.

(b) Bentonite shall be applied at a rate recommended by the manufacturer or an independent soil expert. Completed soil-bentonite liners shall contain a minimum of 5% bentonite by dry weight.

(c) Ninety percent of the bentonite by weight shall pass a No. 80 sieve.

(d) Bentonite shall be thoroughly admixed with the soil throughout the entire thickness of each lift.

(e) Soil-bentonite liners shall be compacted to at least 85% of the maximum standard proctor dry density.

(f) Soil-bentonite liners shall be constructed under the direct supervision of a qualified representative of the bentonite manufacturer, soil technician or engineer, or geotechnical engineer.

(3)   Synthetic liners.

(a) Synthetic liners shall have a minimum thickness of 30 mils.

(b) Synthetic liners shall be installed under the direct supervision of a qualified manufacturer's representative.

(c) To a depth of 6 inches below the bottom of synthetic liners, the soil shall be free from large rocks, angular stones, soil clumps, sticks or other material which may puncture the liner.

(d) Synthetic liners shall be securely anchored into the dike berm.

(e) Venting shall be provided beneath synthetic liners to prevent failure as a result of backpressure from gas accumulation or fluctuations in the watertable elevation. If a liner cover is provided, this requirement may be waived.

(f) Prior to constructing synthetic liners, the underlying soils shall be treated with an herbicide in accordance with the manufacturer's recommendations.

History: Cr. Register, July, 1984, No. 343 , eff. 8-1-84; renum. from NR 213.08, Register, June, 1990, No. 414 , eff. 7-1-90.