Section R. 299.4920 - Landfill construction; hydraulic conductivity testing for cohesive soilsRule 920.
(1) The hydraulic conductivity of cohesive soils shall be determined by 1 of the following test methods:(a) ASTM D5084-90, as amended by the procedures specified pursuant to the provisions of subrule (2) of this rule.(b) A method approved by the department.(2) Specific procedures for conducting hydraulic conductivity tests on cohesive soils shall be documented in the operating record and submitted with test results. Such procedures shall include all of the following: (a) The sample size to be used. To minimize the effects of sample deformation, a sample shall have a minimum diameter of 2.5 inches and a length to diameter ratio between 0.5 and 1.0.(b) Methods of preparing the sample. Methods shall be designed to minimize deformation.(c) Methods of controlling sample temperature. The temperature of the sample shall be maintained at or near 20 degrees Celsius.(d) The permeant to be used. An appropriate permeant shall be 1 of the following: (i) Leachate that is representative of the leachate to be generated.(ii) A 0.01 N solution of CaSo4, to replicate leachate.(iii) Other permeants that are representative of site conditions.(e) Temperature range of the permeant to be used. To avoid the release of dissolved gases, the permeant temperature shall equal or exceed the temperature of the soil sample.(f) The maximum hydraulic gradient to be used. The maximum hydraulic gradient shall be limited as necessary to prevent sample deformation.(g) Methods of minimizing sample compaction by the permeameter.(h) Cross-sectional area of the standpipe.(i) Confining pressure to be used. Confining pressures shall be maintained between 1 and 5 psi above influent or effluent pressure and shall not exceed the natural overburden pressure.(j) The method of determining that steady state conditions have been achieved. All tests shall be continued until steady state conditions have been achieved between influent and effluent.(3) Hydraulic conductivity test results shall be accompanied by data that demonstrate compliance with the procedures specified in subrule (2) of this rule, including all calculations made to determine hydraulic conductivity.(4) The solid waste control agency shall approve a variance to the procedures specified in subrule (2) of this rule if an applicant shows that, for a given sample, the procedure is not feasible or prudent.(5) ASTM procedure D5084-90, is adopted by reference in R 299.4135.Mich. Admin. Code R. 299.4920