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Two observation wells, SOM-13 and B-32 (location B-29W) are located in the • <br />vicinity of the proposed refuse disposal area and have been monitored for <br />static water levels and water quality for the past five years. Data from <br />these wells are available in the Mt. Gunnison Quarterly Hydrology Reports. <br />There are no known aquifers between the bottom of the pile and the F- <br />Seam. Rather there are several narrow bands of perched water above clay <br />layers found in the Barren Member of the Mesa Verde Formation. The <br />perched groundwater is seasonal and appears to discharge downdip as <br />seasonal seeps along the steeper slopes in the vicinity of the landslide near <br />the portals. Most seepage from the refuse disposal area would be <br />intercepted by the underdrains. However, water that manages to percolate <br />past the under-drains would be intercepted by the clays as perched <br />groundwater only to resurface in seasonal seeps on-site where it would be <br />- subject to treatment prior to discharge under the Mt. Gunnison NPDES <br />permit. <br />Monitoring of the groundwater in this area has been part of Mt. Gunnison's \ <br />_ on-going hydrologic monitoring program. Water level data collected from <br />the two observation wells within the proposed disposal site, SOM-13 and <br />B-32 (location B-29W), show that the phreatic surface of the water table has <br />been at or near the bedrock interface since monitoring began in 1976. See <br />- Figures 2 and 3. <br />-• The underdrain system shown in Drawing 001, designed for this refuse pile, <br />will divert leachate from the pile to the drainage system for treatment prior <br />•_ to discharge. Furthermore, a hydrology monitoring program will be <br />established to monitor for any possible hydrologic impacts. <br />Archaeology <br />For a discussion of the archaeological survey conducted in the <br />` environmental study area see Section 2.9 of the Mt. Gunnison M and R Plan. <br />No properties within the area of the proposed refuse disposal site meet the <br />criteria of eligibility for the National Register of Historic Places. • <br />n <br />LJ <br />-8- <br />