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<br />(( <br /> <br />c( <br /> <br />lc <br /> <br />. <br /> <br />C"'"l <br />lr.' <br />t' <br />r.~ <br />C~ <br />08. <br />. <br /> <br />23 <br /> <br />FUTURE CONSIDERATIONS <br /> <br />Based on our studies, there are several important concerns that <br />should be addressed prior to final design. These are as <br />follows: <br /> <br />o Design Criteria for Seepage--the allowable seepage rate <br />to meet regulatory concerns and promote efficient <br />evaporation need to be defined. Based on the established <br />design seepage rate, more detailed field and laboratory <br />studies as well as seepage analyses can be performed. <br /> <br />o Site Geology--the Colorado Geologic Survey has raised <br />concerns with the nature of tbe pediment materials and <br />Mancos shale in the McDonald Creek drainage. Their <br />concerns center on possible faults or folding in this <br />area which could affect the long term integrity of the <br />liners placed at this site. The significance of this <br />problem on site development should be addressed. If <br />seepage is not a concern, then this becomes a non- <br />problem; otherwise additional field studies may be <br />required to better define the geology and faults in this <br />area and their potential influence on development. <br /> <br />o Seepage Analyses--for final design, a more rigorous <br />seepage analysis should be performed. This will require <br />additional field and laboratory studies which should <br />include: <br /> <br />measuring the in situ permeability of the near surface <br />Mancos shale and Mancos shale at depths greater than <br />60 feet <br /> <br />the influence of saline waters on the permeability of <br />proposed liner materials, slurry wall backfill, and <br />in situ soils and bedrock <br />