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APPENDIX U <br />methods, software programs, etc.) survey measurements to project the data to locations <br />stacked above subgrade surface survey locations for the determination of feature <br />thickness, slope and elevation. Alternatively, soil drainage layer material thickness may <br />be measured using appropriate means other than vertical survey methods (e.g., physical <br />measurements, etc.). <br />Survey of sumps should be performed at locations and at distance intervals sufficient to <br />give a clear presentation of the three-dimensional configuration of sump components and <br />their corresponding thicknesses. Similarly, survey of pipe segments (e.g., at points <br />located along top of pipe) should be performed at maximum 50 -foot intervals, at changes <br />in pipe direction and at the ends. <br />Subgrade - QA/QC design requirements for subgrade should focus on achieving a stable <br />surface suitable for liner construction/installation. The subgrade should be free of <br />deleterious material and be reworked as necessary to overcome the effects of adverse <br />weather or other undesirable conditions. The subgrade may have acceptability criteria <br />relative to the surface underlying the liner such as particle size limitations and or relative <br />roughness requirements, etc., depending on the liner design components. QA/QC design <br />requirements for structural fill should ensure suitability and proper placement/compaction <br />of the backfill material. <br />Soil Liners - Similarly, QA/QC design requirements for compacted low permeability soil <br />liners should ensure suitability of liner material, proper placement/compaction and <br />subsequent protection (e.g., from freezing and desiccation). Soil liners should have <br />limitations on particle/clod size. To facilitate positive drainage towards the sump, the <br />soil liner surface should be smooth and free of undulations. Additionally, an evenly <br />graded soil liner surface enhances attainment of intimate contact with an overlying <br />geomembrane so as to form a composite liner. <br />Soil Liner Index Tests/Field Identification Methods/One Point Proctors - Application <br />of professional judgment, laboratory index tests (e.g., gradations and Atterburg Limits), <br />Field Identification of Soils (ASTM D2488 — Visual Manual Procedure) and one point <br />proctors are methods that can be used to aid in determination of changes in soil types to <br />facilitate usage of an appropriate proctor compaction curve for field moisture/density <br />testing of the compacted low permeability soil liner. In general, a minimum of one one <br />(1) point proctor should be performed per each day of cohesive soil liner placement. <br />Field identification methods include, but are not limited to, the following <br />properties/techniques: Color, Grain size, Moisture, Density, Dry Strength (measure of <br />clay content by allowing a small specimen to dry and compressing with fingers), and <br />Toughness Test (measure of clay content by ease of rolling and re -rolling a small <br />specimen into approximately 3 mm diameter threads). <br />An Acceptable Zone (AZ) procedure based on using a "line of optimums " is the preferred <br />method for developing moisture/density specifications for construction of a compacted <br />low permeability soil barrier, which exclusively requires a hydraulic conductivity of I x <br />10-7 cm/s or less, compared with using 'percent compaction " in conjunction with a range <br />of moisture content requirements. The line of optimums is defined as the locus of <br />optimum moisture content/maximum dry density points for compaction curves developed <br />PR -02 10/12 <br />