1. (a) A landfill must have an approved soils and liner quality control plan (SLQCP) prepared under the direction of a registered professional engineer, and it shall be the basis for the type and rate of quality control testing performance and reported in the soil and liner evaluation report (SLER) as required in §330.206 of this title (relating to Soils and Liner Evaluation Report (SLER) and Flexible Membrane Liner Evaluation Report (FMLER)). The SLQCP must be included in the site development plan to provide operating personnel adequate procedural guidance for assuring continuous compliance with groundwater protection requirements. The plan shall specify construction methods employing good engineering practices for compaction of clay soils to form a liner. Unless alternate construction procedures are approved in writing by the executive director, all constructed liners shall be keyed into an underlying formation of sufficient strength to ensure stability of the constructed lining. The SLQCP shall address the installation and testing of an FML liner, if used. Proposed dewatering plans shall be included. The SLQCP shall include the following information.

   1. (1) Constructed liner details, where applicable shall be depicted on cross-sections of a typical trench showing the slope, widths, and thicknesses for compaction lifts. The amount of compaction shall be expressed as a percentage of a predetermined laboratory density.
   2. (2) Soil and liner quality-control testing procedures, to include sampling frequency, shall be included in the SLQCP. All field sampling and testing, both during construction and after completion, shall be performed by a person acting in compliance with the provisions of the Texas Engineering Practice Act and other state laws and regulations. The professional of record who signs the soils and liner evaluation report (SLER) or his representative should be on site during all liner construction. Quality control of construction and quality assurance of sampling and testing procedures should follow the latest technical guidelines of the executive director.

2. (b) An SLQCP shall also:

   1. (1) describe and illustrate, for operating personnel, all necessary procedures for assuring continuous compliance with this subsection;
   2. (2) provide guidance needed for testing and reporting evaluation procedures to the professional who will prepare the SLERs for the site;

   3. (3) specify materials, equipment, and construction methods for the compaction of clay soils to form impermeable liners for the conditions described in subparagraphs (A) and (B) of this paragraph. The SLQCP shall adhere to the testing frequencies and procedures as specified.

      1. (A) Details for the overexcavation and recompaction of the in-situ soils, or the compaction of soils from a borrow source, shall be depicted on cross-sections of a typical trench showing the slope, widths, and thicknesses for compaction lifts.
      2. (B) Procedures to be followed when excavations, trenches, or disposal areas extend into or have the potential to extend into the groundwater shall be in accordance with the provisions provided in §330.203 of this title (relating to Special Conditions (Liner Design Constraints)); and
   4. (4) describe installation methods and quality control testing and reporting for any FML that may be required or authorized by the executive director as a part of a composite liner.

3. (c) Soil liner quality control testing frequencies and procedures shall be in accordance with the executive director's most recent guidelines and the following.

   1. (1) All field sampling and testing, both during construction and after completion of the lining, shall be performed by a qualified professional experienced in geotechnical engineering and/or engineering geology, or under his direct supervision.
   2. (2) All liners should have continuous on-site inspection during construction by the professional of record or his designated representative.
   3. (3) The amount of compaction of clay liners shall be expressed as a percentage of a maximum dry density based on a compaction test specified by a registered professional engineer. The compaction of the clay liner shall have been proven by soils laboratory testing to provide a coefficient of permeability of 1 x 10[sup]-7[/sup] cm/sec or less.

   4. (4) The SLQCP shall define the frequency of testing for each of the test procedures listed in subparagraphs (A)-(F) of this paragraph. These frequencies shall be expressed in numbers of tests per specific area of liner per lift or specific thickness of liner, unless an alternate frequency is approved by the executive director:

      1. (A) coefficient of permeability;
      2. (B) Sieve analysis;
      3. (C) Atterberg limits;
      4. (D) density;
      5. (E) moisture content;
      6. (F) thickness verification.

   5. (5) Unless otherwise approved by the executive director, all soil tests performed on any in-situ or constructed soil liners shall be in accordance with the standards in subparagraphs (A)-(E) of this paragraph:

      1. (A) laboratory permeability tests. Permeability tests shall be run using tap water or .05N solution of CaSO[sub]4[/sub] and not distilled water. All test data must be submitted on permeability tests regardless of test method used. At a minimum, the calculations of the last data set reported for each sample and the resultant coefficient of permeability shall be reported as supporting data. Tests shall be either constant head with back pressure (Appendix VII of Corps of Engineers Manual, EM 1110-2-1906; ASTM D5084, "Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter") or falling head (Appendix VII of Corps of Engineers Manual, EM1110-2-1906);
      2. (B) Sieve analysis +1, 200, -200 sieves (ASTM D422 or ASTM D1140, as applicable);
      3. (C) Atterberg limits (ASTM D4318);
      4. (D) moisture-density relations (ASTM D698 or any executive-director-approved modified test whose compactive effort matches the on-site construction equipment);
      5. (E) moisture content (ASTM D2216).
   6. (6) All soils used as constructed liners must have the following minimum values verified by testing in a soils laboratory: plasticity index--equal to or greater than 15; liquid limit--equal to or greater than 30; percent passing 200 mesh sieve (-200) equal to or greater than 30%; percent passing one-inch screen--100%; coefficient of permeability less than or equal to 1 x 10[sup]-7[/sup] cm/sec.
   7. (7) Permeability tests for proving the suitability of soils to be used in constructing clay liners shall be performed in the laboratory using the procedures and guidance of paragraph (5)(A) of this subsection. Field quality control must be provided by field density tests based on predetermined moisture-density compaction curves, Atterberg limits, and laboratory permeabilities of undisturbed field samples of compacted liner soils, unless an alternate plan is approved by the executive director.
   8. (8) Field permeability testing of in-situ soils or constructed soil liners shall be in accordance with ASTM D 5093 for those soil liners which are in the floor of the excavation and a variation of the Boutwell STEI field permeability test approved by the executive director for the sidewalls, or in accordance with guidance furnished by the executive director.
   9. (9) All quality control testing of soil liners shall be performed during the construction of the liner. In no instance shall any quality control field or laboratory testing be undertaken after completion of liner construction, except for that testing which is required of the final constructed lift, confirmation of liner thickness, or cover material thickness.
   10. (10) All soil testing and evaluation of either in-situ soil or constructed soil liners shall be complete prior to installing the LCS or, if no LCS is required, prior to adding the one foot of protective cover on the area under evaluation.
4. (d) Soil and liner density shall be expressed as a percentage of the maximum dry density and at the corresponding optimum moisture content specified as appropriate by a registered professional engineer experienced in geotechnical engineering. These soils so compacted must upon testing either in the laboratory or as a test pad in the field demonstrate a coefficient of permeability no greater than 1 x 10[sup]-7[/sup] cm/sec.
5. (e) Unless alternate construction procedures have prior written approval by the executive director, all constructed soil liners shall be keyed into an underlying formation of sufficient strength to ensure stability of the constructed lining.
6. (f) Each SLER shall be prepared in accordance with the approved SLQCP. Any deviation from an approved SLQCP must have prior written approval from the executive director.
7. (g) Soil liners shall not be compacted with a bulldozer or any track-mobilized equipment unless it is used to pull a pad-footed roller. All soil liners shall be compacted with a pad-footed or prong-footed roller only. The maximum clod size of the compacted liner soils shall be approximately one inch in diameter. In all cases soil clods shall be reduced to the smallest size necessary to achieve the coefficient of permeability reported by the testing laboratory and to destroy any macrostructure evidenced after the compaction of the clods under density-controlled conditions.
8. (h) The liner soil material shall contain no rocks or stones larger than one inch in diameter or that total more than 10% by weight. Rock content shall not be a detriment to the integrity of the overlying geomembrane.

Source Note:The provisions of this §330.205 adopted to be effective October 9, 1993, 18 TexReg 4023.