Mich. Admin. Code R. 299.4423

Current through Vol. 24-10, June 15, 2024

Section R. 299.4423 - Type II landfill design standards; leachate collection and removal systems

Rule 423.

(1) All new units and lateral extensions of existing units at a type II landfill shall have a leachate collection system that is designed and constructed to maintain less than a 1-foot depth of leachate over the primary liner. To do so, the system shall be designed to do all of the following :

(a) Limit the head at any point in the system, excluding the sump, to not more than 1 foot using the design criteria specified in this rule or alternate criteria demonstrated under subrule (5) of this rule.

(b) Extend across the entire bottom of the system.

(c) Be chemically resistant to the waste that is managed in the landfill and the leachate that is expected to be generated and be of sufficient strength and thickness to prevent collapse under the pressures that are exerted by overlying wastes, waste cover materials, and equipment that is used at the landfill.

(d) Minimize clogging during the active life and postclosure care period.

(e) Drain leachate to sumps using pumps that are of a sufficient size to collect and remove liquids from the sump and prevent liquids from backing up into the drainage layer. Each unit shall have its own sump. The design of each sump and removal system shall provide a method for measuring and recording the volume of liquids removed and the depth of leachate in the sump.

(2) Except as provided in subrule (5) of this rule, a leachate collection system shall consist of a soil drainage layer that is designed to the following requirements:

(a) Is a minimum of 1 foot thick and has a hydraulic conductivity equal to or greater than either of the following:

(i) 1.0 x 10-2 centimeters per second.

(ii) 1.0 X 10-3 centimeters per second, if used in conjunction with a geonet or other synthetic drainage material that has a hydraulic conductivity of 1 centimeter per second.

(b) Is free of any organic material and has less than 5% of the material, by weight, pass the Number 200 sieve.

(c) Is placed on a minimum slope of 2% in directions perpendicular to perforated pipes to promote drainage and prevent ponding above the liner.

(d) Is used in conjunction with perforated pipes that are in compliance with the subrule (3) of this rule.

(e) Is free of angular stones or other debris that may puncture, tear, or otherwise damage any flexible membrane liner adjacent to the drainage layer, unless a geosynthetic is provided over the liner to prevent such puncture.

(f) Is capable of preventing puncture of the liner by waste. To do so, the owner or operator may do any of the following:

(i) Increase the thickness to 2 feet using soil that has a hydraulic conductivity of at least 1.0 x 10-4 cm/sec.

(ii) Install a geosynthetic designed to prevent puncture of the liner.

(iii) Limit the type of waste received in the first 5 feet of the unit.

(3) Except as provided in subrule (5) of this rule, a leachate collection system shall include perforated pipes to aid in drainage. The pipes shall be designed to meet all of the following requirements:

(a) Have a wall thickness that is sufficient to withstand overburden pressures.

(b) Have a diameter that is sufficient to withstand the maximum design flow.

(c) A slope of 1% or more in a direction to intercept liquid flow. In addition, an applicant for a new disposal area shall demonstrate that the bottom slope will be 1% or more after consolidation settlement, except as provided for vertical expansions of a unit in R 299.4419.

(d) Be constructed with sufficient manholes and cleanout risers to allow for the cleaning and maintenance of pipes.

(e) Be spaced not more than 50 feet from the high point of the drainage layer. Perforated pipes may be spaced at greater distances, based on a demonstration under subrule (5) of this rule.

(4) All leachate collection systems shall include a filter layer, if necessary, to prevent clogging. A filter layer shall consist of 1 or both of the following:

(a) A graded, cohesionless soil filter which does not have more than 5%, by weight, that passes the no. 200 sieve and which does not permit the passage of soil particles that are more than 3 inches in any dimension.

(b) A geotextile filter that has both of the following:

(i) A hydraulic conductivity, as determined by ASTM D4491, that is capable of passing the projected inflow.

(ii) An apparent opening size that is in compliance with both of the following criteria:

(A) O₉₅ of the geotextile divided by d₈₅ of the soil is less than 2, where the O₉₅ is the apparent opening size of the geotextile at which 5% or less of the soil particles will pass and where the d₈₅ is the soil particle size at which 85% of the sample is finer.

(B) The opening is designed to minimize the influence of retained particles on the permitivity of the geotextile.

(5) The owner and operator of a type II landfill may propose the use of an alternative drainage system design for a primary leachate collection system if the owner and operator can demonstrate, using mounding calculations and data on liner slope, drainage layer permeability, and flow length, that the alternative system will limit the head on the liner to the same extent as the design specified in subrule (3) of this rule and protect the liner system from waste, ultraviolet light, and other deleterious effects.

(6) A new unit and lateral extension of an existing unit at a type II landfill shall have a system for storing leachate outside the active portion if necessary to maintain compliance with the leachate depth requirements of R 299.4432(1). Tanks that are used to store leachate shall be in compliance with the technical standards of 40 C.F.R. §264.193. Surface impoundments, if used, shall be in compliance with the technical standards of 40 C.F.R.§264.221 and shall be operated in a manner that does not create a nuisance. The provisions of 40 C.F.R. §264.193 and 40 C.F.R. §264.221 are adopted by reference in R 299.4136.

Mich. Admin. Code R. 299.4423

1993 AACS; 1999 AACS

An obvious error in R 299.4423 was corrected at the request of the promulgating agency, pursuant to Section 56 of 1969 PA 306, as amended by 2000 PA 262, MCL 24.256. The rule containing the error was published in Annual Administrative Code Supplement,1999 . The memorandum requesting the correction was published in Michigan Register, 2012 MR 18