R 323.2237 Wastewater treatment or storage lagoons.

Rule 2237. (1) Except as provided in subrule (4) of this rule, wastewater treatment or storage lagoons associated with a discharge shall consist of a composite liner with a base that meets the requirements of subrule (2) of this rule and a liner as described in subrule (3) of this rule. (2) The base of the composite liner required by this rule shall be a natural soil barrier that meets the criteria of subdivision (a) of this subrule, a compacted soil barrier that meets the criteria of subdivision (b)of this subrule, or a geocomposite clay liner that meets the criteria of subdivision (c) of this subrule as follows: (a) A natural soil barrier used as a base in a composite liner system shall meet all of the following requirements: (i) The natural soil shall be free of sand lenses and not less than 10 feet thick. (ii) The soil shall have a saturated vertical hydraulic conductivity of not more than 1 x 10- 7 centimeters per second. The hydraulic conductivity of the soil shall be determined using ASTM method D5084-90, which is adopted by reference in R 323.2238, as modified by the department in R 299.4920. If flexible wall permeameters are used, then confining pressures shall be equivalent to the minimum pressure expected after the lagoon is placed in service. (iii) For abovegrade construction or if the lagoon liner base does not extend to the ground surface, perimeter dike walls shall be constructed using a soil that meets the criteria of subdivision (b)(ii) and (iii) of this subrule and keyed into the natural soil base. (iv) The natural soil liner surface shall be prepared for placement of the flexible membrane liner (FML) to remove the potential for failures to the FML. (v) Alternative test and investigative methods may be approved by the department. (vi) An engineer licensed under Act No. 299 of the Public Acts of 1980, as amended, being §339.101 et seq. of the Michigan Compiled Laws, and known as the occupational code, shall certify to the department, through spatially random testing and measurements, that the requirements of this rule were met during installation of the natural soil base of the composite liner. At least 1 soil test shall be conducted and an additional test shall be conducted for every 5,000 cubic yards placed and when the texture of the soil changes. (b) A compacted soil liner used as a segment of the composite liner system shall meet all of the following requirements: (i) The compacted soil liner shall have a minimum thickness of 2 feet. (ii) The relationship between hydraulic conductivity, moisture, and density shall be established with laboratory testing for the source of clay that will serve as the compacted clay portion of the composite liner. The relationship shall be determined using either the modified proctor test, ASTM D1557-91, which is adopted by reference in R 323.2238, or the standard proctor test, ASTM D698- 91, which is adopted by reference in R 323.2238. (iii) Each lift shall be thoroughly and uniformly compacted to achieve a hydraulic conductivity of not more than 1 x 10-7 centimeters per second based upon the density and moisture content determined under subdivision(b)(ii) of this subrule. The hydraulic conductivity of the soil shall be determined using ASTM method D5084-90, which is adopted by reference in R 323.2238, as modified by the department in R 299.4920. If flexible wall permeameters are used, then confining pressures shall be equivalent to the minimum pressure expected after the lagoon is placed in service. Soil shall not be compacted at a moisture content that is less than optimum and shall not be compacted to less than either of the following densities: (A) Ninety percent of the maximum dry density, as determined by the modified proctor test, ASTM D1557-91, which is adopted by reference in R 323.2238. (B) Ninety-five percent of the maximum dry density, as determined by the standard proctor test, ASTM D698-91, which is adopted by reference in R 323.2238. (iv) The soil shall be placed so that each lift shall not be more than 6 inches after compaction. (v) For abovegrade construction or if the lagoon liner base does not extend to the ground surface, perimeter dike walls shall be constructed using a soil that meets the criteria of paragraphs (ii) and (iii) of this subdivision and keyed into the compacted soil base. (vi) The compacted soil liner surface shall be prepared for placement of the FML to remove the potential for failures of the FML. (vii) Alternative test and investigative methods may be approved by the department. (viii) An engineer licensed under Act No. 299 of the Public Acts of 1980, as amended, being §339.101 et seq. of the Michigan Compiled Laws, and known as the occupational code, shall certify to the department, through spatially random testing and measurements, that the requirements of this rule were met during installation of the compacted soil base of the composite liner. At least 1 soil test of the compacted soil shall be conducted and an additional test shall be conducted for every 5,000 cubic yards placed and when the texture of the soil changes. (c) A geocomposite clay liner (GCL) used as a segment of a composite liner shall meet all of the following requirements: (i) The GCL shall be a factory-manufactured hydraulic barrier consisting of sodium betonite clay supported by geotextiles that are held together by needling, stitching, or adhesives. (ii) The GCL shall be seamed according to the manufacturer's specifications to prevent leakage at the seams. (iii) The GCL shall not be laid during a precipitation event and shall be covered immediately by a flexible membrane liner or by another protective cover until the flexible membrane liner can be laid directly over the GCL. (iv) The GCL shall be installed according to the manufacturer's specifications and quality assurance and quality control plans and shall be certified by an engineer licensed under Act No. 299 of the Public Acts of 1980, as amended, being R 339.101 et seq. of the Michigan Compiled Laws, and known as the occupational code, overseeing the installation of the composite liner. (3) An FML required by this rule shall be placed directly over a liner described in subrule (2) of this rule to form the composite liner. The FML and its installation shall comply with all of the following requirements: (a) The liner shall be a minimum of 40 mils thick polyvinyl chloride (PVC) or 60 mils thick high-density polyethylene (HDPE). The discharger may utilize other materials and thickness if the department determines before installation, that the proposed material and thickness are sufficient to ensure that the integrity of the liner is not compromised due to contact with the soil base, wastewater, climatic conditions, or the stress of installation or daily operation. (b) An FML shall be covered immediately after placement by an adequate thickness of soil or other material approved by the department to prevent puncture by equipment and to protect the exposed portion of the FML from degradation by ultraviolet light. (c) The FML shall be placed upon a foundation or base capable of providing support to the liner and resistance to pressure gradients above and below the liner to prevent slope failure and failure of the liner due to settlement, compression, or uplift. (d) The FML shall be installed to cover the entire area of earth material that would be in contact with the treated or stored effluent. (e) An FML shall be placed on slopes that are not more than 25%, unless the owner and operator can demonstrate slope stability for greater slopes. (f) The field seams of an FML shall meet all of the following requirements: (i) Seaming shall be done in accordance with the minimum industry standards. The shear strength and peel strength of the seams must be adeqaute to maintain the ingetrity of the seam under all operating conditions. (ii) Horizontal seams shall not occur on side slopes. (iii) Horizontal seams shall be located not less than 5 feet from the toe of the slope. (iv) Field seams shall be installed parallel to the line of maximum slope. (v) The seam area shall be free of moisture, dust, dirt, debris, and foreign material of any kind before seaming. (vi) Field seaming shall not be done in weather conditions that would adversely affect the integrity of the seam. (g) An engineer licensed under Act No. 299 of the Public Acts of 1980, as amended, being §339.101 et seq. of the Michigan Compiled Laws, and known as the occupational code, shall certify to the department that all necessary quality assurance testing was conducted to ensure that the FML was installed to meet the conditions of these rules. (4) The department may approve a storage or treatment lagoon liner that does not meet 1 or more of the requirements of this rule if the applicant demonstrates that the requirements of either of the following provisions are met: (a) The lagoon holds only wastewater that meets the standards of R 323.2222. (b) The existing system or the proposed design provides equal or greater environmental protection to protection provided by a lagoon liner constructed according to this rule. For an existing system, the demonstration can be made by either of the following: (i) Through an exfiltration test that demonstrates, to the department's satisfaction, that the lagoon is not leaking at a rate likely to impact groundwater above the standards described in R 323.2222. (ii) Through monitoring of the groundwater and a demonstration approved by the department that the lagoon has not impacted, and is not likely to impact, groundwater above the standards described in R 323.2222.