Md. Code Regs. 26.21.04.06

Current through Register Vol. 51, No. 22, November 1, 2024

Section 26.21.04.06 - Leachate Control and Collection

A. Minimum Requirements.

(1) The use of coal combustion byproducts in the reclamation of a noncoal surface mine requires the installation of a liner and leachate control and collection system that meets the minimum requirements of this section.

(2) A liner system shall be designed, constructed, and installed to facilitate collection of leachate generated from the coal combustion byproducts to prevent migration of pollutants to the adjacent subsurface soil, ground water, or surface water. The subbase referenced below shall be constructed of natural earthen materials which are excavated from on the site or which are imported from another location, or of a synthetic or manufactured membrane material. The liner system shall be:

(a) Constructed of materials that have sufficient strength and thickness to prevent failure due to pressure gradients, physical contact with the coal combustion byproducts or leachate, climatic conditions, the stress of installation, and the stress of daily operation;

(b) Constructed of one or more unreinforced synthetic membranes with a combined minimum thickness of 50 mil, or a single reinforced synthetic membrane with a minimum thickness of 30 mil, which has a permeability less than or equal to 1 x 10^-10 centimeters/second, placed over a prepared subbase with a minimum thickness of 2 feet and a permeability less than or equal to 1 x 10^-5 centimeters/second, unless the Department authorizes the installation of a liner system with specifications different than those listed in this paragraph only upon a successful demonstration by the permittee that:

(i) The alternate system is capable of collecting and managing the leachate generated at the site; and

(ii) The liner system provides an equivalent level of protection to public health and the environment;

(c) 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 failure of the liner due to settlement, compression, uplift, puncture, cutting, or activities at the site;

(d) Installed to cover all surrounding earth likely to be in contact with the coal combustion byproducts or leachate;

(e) Installed with a minimum slope of 2 percent to facilitate movement of leachate towards the leachate collection system and prevent leachate from ponding on the fill floor; and

(f) Located entirely above the composite high water table and bedrock, with a minimum buffer distance of 3 feet between the bedrock elevation and the maximum expected ground water elevation, and the bottom of the liner system including the thickness of the prepared subbase.

(3) A leachate collection and removal system, located immediately above the liner shall be designed, constructed, maintained, and operated to collect and remove leachate generated from the coal combustion byproducts. The leachate collection and removal system shall be:

(a) Constructed of materials that are chemically resistant to the coal combustion byproducts and the leachate expected to be generated, and of sufficient strength and thickness to prevent collapse under the pressures exerted by overlying coal combustion byproducts, cover and other materials, and by any equipment used at the site;

(b) Designed and operated to function without clogging; and

(c) Designed and operated to ensure that the leachate depth over the liner does not exceed 12 inches.

B. Based on site conditions, the size and design of the project, and other considerations as determined by the Department, the Department may require other liner and leachate control and collection requirements it considers necessary to protect public health and the environment.

Md. Code Regs. 26.21.04.06