(b) Due to the unique land formations in northwest Arkansas, the following information and studies are required to characterize any site proposed for a Class I or Class II landfill and must be submitted to the district:

1. (1) Fracture trace analysis from aerial photographs of the proposed site;

2. (2)

   1. (A) Detailed surface geologic mapping of the site and the area within one (1) mile of the boundary of the site.
   2. (B) The following information must be obtained:

(i) The stratigraphy of the study area; and

1. (ii) Structure of the study area:

(b) (b) Fracture spacing and fracture orientation for each stratigraphic unit identified; and

1. (c) (c) Location of karst features including, but not limited to:
2. (1) (1) Sinkholes;
3. (2) (2) Springs;
4. (3) (3) Losing and disappearing stream segments;
5. (4) (4) Caves (must be mapped within the study area); and
6. (5) (5) Dolens;

7. (3) Subsurface exploration must evaluate the following:

   1. (A) Overburden.

      1. (i) Thickness and areal extent of each distinct textural horizon as defined by borings and test pits.
      2. (ii) Quality of soils (physical properties) must be determined for each stratigraphic or pedologic horizon including:

(b) (b) Sieve analysis and grain size distribution curves (ASTM D 1140 and D 422);

1. (c) (c) Standard penetration tests (ASTM D 1452);

   1. (d) (d) Remolded hydraulic conductivity test (ASTM D 5084);

(g) (g) Moisture contents (ASTM D 2216).

1. (iii)

(b) (b) Borings shall be at a minimum spacing of one (1) per five (5) acres.

1. (c) (c) Trackhoe pits shall be at a minimum spacing of one (1) per acre;

   1. (B) Bedrock topography.

      1. (i) Core drilling on at least one (1) hole per five (5) acres with:

(b) (b) Fracture orientation; and

1. (c) (c) Sudden gains or losses of drilling fluid.

   1. (ii) Geophysical logs of borings including:

(b) (b) Conductivity;

1. (c) (c) Caliper;

   1. (d) (d) Natural gamma;

(g) (g) Temperature.

1. (iii)

(b) (b) Geophysical surveys must be correlated with borings.

1. (c) (c) The proposed geophysical study of the site must include two (2) or more of the following methods:
2. (1) (1) Ground penetrating radar;
3. (2) (2) Surface conductivity;
4. (3) (3) Resistivity;
5. (4) (4) Shallow seismic refraction; and

6. (5) (5) Shallow seismic reflection;

   1. (C) Hydrogeology.

      1. (i) Potentiometric surface of the aquifer.
      2. (ii) Preferred contaminant transport pathways determined by dye traces.
      3. (iii) Aquifer properties using the following methods:

(b) (b) Pump tests using appropriate methodology for the aquifer and using multiple observation wells; and

1. (c) (c) A single well aquifer test.

   1. (iv) A recommended groundwater monitoring system consisting of wells and springs must be developed.

      1. (v)

(b) (b) At least one (1) year of data must be collected at quarterly intervals to demonstrate seasonal ambient water quality variability; and

1. (D)

   1. (i) All individual studies must be integrated into a comprehensive geologic and hydrogeologic model of the site which is summarized in a written report.

      1. (ii) The facility groundwater monitoring points must be located based upon the hydrogeologic model developed for the site.
      2. (iii) All maps and cross sections must be of a uniform scale (the same size as used in the design blueprints, typically one inch equals fifty feet (1" = 50') to one inch equals four hundred feet (1" = 400')) and must include the following:

(b) (b) Boring locations;

1. (c) (c) Geophysical lines or data collection points;

   1. (d) (d) Potentiometric maps dye study results;