Section 213.10. General liner specifications.

 

(1)   General.

(a) All lagoons shall be sealed to prevent excessive exfiltration.

1. Natural soil materials, soil-bentonite mixtures or synthetic liners approved by the department may be used as lagoon liners.

2. All liners shall be constructed with materials compatible with the wastewater to be contained by the lagoon.

3. Prior to installation of any type of liner, the lagoon bottom shall be compacted to a depth of 6 inches, at a minimum to 95% of the maximum standard proctor dry density, at or above optimum moisture.

4. All liners shall be constructed to provide a uniform barrier to exfiltration across the lagoon bottom, interior dike walls and extending up the dike wall to the berm.

5. The department may require a liner to be protected by an inorganic layer of soil or crushed stone if necessary to protect against such things as photochemical reaction, ice or wave action, freeze-thaw action, liner floatation or vehicular traffic on the liner. This layer shall have a minimum thickness of one foot and be uniformly graded and free from large rocks, soil clumps and sticks. If a granular noncohesive soil is used, the department may require that a soil fabric securely attached to the berm be placed between the liner and the cover material to prevent slumping of the cover material.

6. Riprap may be required along the air-water interface if necessary to minimize rodent activity or exposure and erosion of the liner or subgrade.

7. For lagoons which will be empty for extended periods of time, a synthetic lining material shall be used to prevent liner degradation as a result of desiccation.

(b) Soil or soil-bentonite liners.

1. The design standard for the co-efficient of permeability of soil or soil-bentonite liners may not exceed 1 x 10 -7 cm/sec.

2. The thickness of soil or soil-bentonite liners shall be determined according to Darcy's equation and shall include an appropriate safety factor for construction variability. See Table 1. - See PDF for table

3. To a depth of 6 inches, a minimum of 15% of the unmodified soil upon which a soil or soil-bentonite liner is to be constructed shall pass a No. 200 sieve. If this requirement cannot be met, a soil filter fabric designed to retain those particles passing a No. 200 sieve shall be placed between the liner and the existing
soil.

4. Soil or soil-bentonite liners shall be compacted at or above optimum moisture.

5. A means shall be provided to prevent soil or soil-bentonite liners from desiccating after completion of construction and prior to placing the lagoon into operation.

(2)   Exfiltration rate.

(a) The design loss of wastewater or sludge from any lined lagoon may not exceed 500 gallons per acre per day.

(b) In circumstances where soil characteristics, groundwater quality, waste characteristics or concern with the liner-waste compatibility warrant, the department may require that more stringent exfiltration rates be met.

History: Cr. Register, July, 1984, No. 343 , eff. 8-1-84; renum. from NR 213.07 and am. (1) (b) 2. and (2) (b), Register, June, 1990, No. 414 , eff. 7-1-90.