SECTION 330.331. Design Criteria

(a) New permits for Type I landfill units, lateral expansions, vertical expansions of Type I landfills over landfills that do not meet the design criteria under paragraph (1) or (2) of this subsection and expansions of existing Type IAE landfills that subsequently no longer satisfy the conditions specified in §330.5(b)(1) of this title (relating to Classification of Municipal Solid Waste Facilities) must be constructed in accordance with one of the following provisions approved by the executive director:

(1) a design that ensures that the concentration values listed in Table 1 of this paragraph will not be exceeded in the uppermost aquifer at the point of compliance, as determined in §330.403 of this title (relating to Groundwater Monitoring Systems); or

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(2) a composite liner, as defined in subsection (b) of this section, and a leachate collection system that is designed and constructed to maintain less than a 30-centimeter depth of leachate over the liner.

(b) For purposes of this section, "composite liner" means a system consisting of two components; the upper component must consist of a minimum 30-mil geomembrane liner and the lower component must consist of at least a two-foot layer of re-compacted soil with a hydraulic conductivity of no more than 1 x 10^-7 centimeters per second (cm/sec). Geomembrane liner components consisting of high density polyethylene (HDPE) must be at least 60-mil thick. The geomembrane liner component must be installed in direct and uniform contact with the compacted soil component.

(c) When approving a design that complies with subsection (a)(1) of this section, the executive director may consider, but is not limited to, the following factors:

(1) the hydrogeologic characteristics of the facility and surrounding land;

(2) the climatic factors of the area;

(3) the volume and physical and chemical characteristics of the leachate;

(4) the quantity, quality, and direction of flow of groundwater;

(5) the proximity and withdrawal rate of the groundwater users;

(6) the availability of alternative drinking water supplies;

(7) the existing quality of the groundwater, including other sources of contamination and their cumulative impacts on the groundwater and whether groundwater is currently used or reasonably expected to be used for drinking water;

(8) public health, safety, and welfare effects; and

(9) practicable capability of the owner or operator.

(d) Type IV landfills must meet one of the following groundwater protection requirements:

(1) there must exist at least four feet of in-situ soil between the deposited waste and groundwater. This in-situ soil must constitute an in-situ liner and must meet all the physical properties for a constructed liner as detailed in §330.339(c)(5) of this title (relating to Liner Quality Control Plan). In-situ liners must not exhibit primary or secondary physical features such as jointing, fractures, bedding planes, solution cavities, root holes, desiccation shrinkage cracks etc., that have a coefficient of permeability greater than 1 x 10^-7 cm/sec;

(2) there must be at least a three-foot thick re-compacted clay liner between the deposited waste and groundwater. The constructed liner must meet all the criteria detailed in §330.339 of this title and must at a minimum have one foot of protective cover overlying the re-compacted liner after all quality control testing and final thickness determinations are complete; or

(3) an alternative liner design, in accordance with §330.335 of this title (relating to Alternative Liner Design).

(e) Municipal solid waste landfill facilities that accept Class 1 industrial solid wastes, other than asbestos-containing material, must have dedicated cells that meet the following requirements.

(1) The cells designated for Class 1 industrial solid wastes must have a composite liner system consisting of two components. The upper component must consist of a minimum of a 30-mil geomembrane liner and the lower component must consist of at least a three-foot layer of re-compacted soil with a hydraulic conductivity of no more than 1 x 10 ^-7 cm/sec. Geomembrane liner components consisting of HDPE must be at least 60-mil thick. The geomembrane liner component must be installed in direct and uniform contact with the compacted soil component. The liner system installed for Class 1 industrial solid waste cells is subject to the requirements of §330.339 of this title. These cells must be designated on facility layout maps.

(2) The cells designated for Class 1 industrial solid wastes must have a leachate-collection system designed and constructed to maintain less than a 30-cm depth of leachate over the liner. The leachate-collection and leachate-removal system must be:

(A) constructed of materials that are chemically resistant to the leachate expected to be generated;

(B) of sufficient strength and thickness to prevent collapse under the pressures exerted by overlying wastes, waste cover materials, and by any equipment used at the landfill; and

(C) designed and operated to function through the scheduled closure and post-closure period of the landfill.

(3) Unless the executive director approves an engineered design that the applicant has demonstrated will provide equal or greater protection to human health and the environment, a new landfill cell or an areal expansion of an existing landfill cell must be located in areas allowed by §335.584(b)(1) and (2) of this title (relating to Location Restrictions).

Source Note: The provisions of this §330.331 adopted to be effective March 27, 2006, 31 TexReg 2502