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XII. Seneca II Technical Revision 45 (2007) Monitoring Program Changes
<br />. Due to the closing of the Seneca II Mine, SCC has requested a reduction in monitoring frequencies of
<br />streams, springs and wells. These reduced monitoring frequencies will be continued until a year or two
<br />before final bond release, at which time monitoring frequencies will be increased. The details of the
<br />changes are provided below.
<br />For ground water monitoring wells, the frequency of water level measurements has been changed from
<br />tri-annual to semi-annual (May/June and SeptemberlOctoberl. Water quality sampling of alluvial and
<br />spoil wells will remain semi-annual. Water quality sampling of bedrock wells will change from semi-
<br />annual to annual IMay/Junel, since the bedrock wells are subject to less change in water quality than the
<br />alluvium or spoils.
<br />Water quality sampling will be discontinued at wells GW-S6-A, GW-S31-A2, GW-S32-A, GW-S33-A, and
<br />GW-S46-A. In the case of the first three wells, they all exist in the Little Grassy Creek Alluvium and are
<br />all downstream of mining areas. However, there is no use of the alluvial water in this area, and a further
<br />downstream well, GW-S70-A, exists in the Grassy Creek alluvium. Well GW-S33-A exists in the Grassy
<br />Creek alluvium downstream of some of the mining area, but GW-S70-A is downstream of the entire
<br />mining area and will continued to be sampled. Well GW-S46-A is in the Cow Camp Creek alluvium, but
<br />GW-S69-A is further downstream and will continued to be sampled. Table 7-99. Ground Water
<br />Monitoring Frequencies, has been revised to reflect these changes. These wells will remain open for
<br />sampling, if necessary, prior to bond release.
<br />For stream sites, monitoring at SW-S2-2, lower Grassy Creek, has been changed from monthly to tri-
<br />annual (spring runoff, post-runoff and baseflow). Monitoring at all other streams in the Grassy Creek
<br />basin will remain tri-annual. Monitoring at stream sites in the Fish Creek basin will remain monthly, May
<br />thru July. For spoil springs, monitoring has been changed from semi-annual to annual IMay to Julyl.
<br />Table 7-103, Surface Water Monitoring Frequencies, has been revised to reflect these changes.
<br />~ ~ References
<br />Colorado Water Quality Control Commission, undated. Notice of Public Rulemaking Hearing Before the
<br />Colorado Water Quality Control Commission, Hearing Date of June 13, 2005.
<br />www. cd ph e. state.co. u s/o p/wgcc/wq cchom.as p
<br />Cooper, H.H., J.D. Bredehoeft, and I.S. Papdopulos, 1967. Response to a fnite diameter well to an
<br />instantaneous charge of water. Water Resources Research, V.3. No. 1, pp. 263-269.
<br />Hem, J.D., 1989. Study and Interpretation of the Chemical Characteristics of Natural Water. U.S.
<br />Geological Survey Water-Supply Paper 2254. 263p.
<br />Office of Surface Mining Reclamation and Enforcement, 1989. "Draft Environmental Impact Statement",
<br />OSMRE-EIS-25.
<br />Skibitzke, H.E., 1963. Determination of the coefficient of transmissibility from measurements of residual
<br />drawdown in a bailed well: In Methods of determining permeability, transmissibility and drawdown, R.
<br />Bentall, complier, U.S. Geological Survey Water-Supply Paper 1536-I, pp. 293-298.
<br />U.S. Environmental Protection Agency (EPA), 1976. Quality Criteria for Water ("Red Book"). Office of
<br />Water and Hazardous Materials. Washington, D.C. 256p.
<br />TR-45 7388 Revised 06/07
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