APPCOR12906 - Laserfiche WebLink

Home Browse Search

-lz- VI. Hydrologic Balance: Ground Water - Rules 2.04.5, 2.04,7 2.05.3(4), 2.05,6(3), and 4.05. Section 2,04.7 (Volume I), Appendix L (Volume V) and Appendix R (Volume VII) were reviewed by the Division for compliance with the above sections of the Colorado Rules and Regulations. Data provided by the applicant is sufficient to make the following findings. Some problems related to the methods for monitoring ground water are evident from the data provided. First of all, high pH values Caere recorded for all of the monthly field chemistry and water level measurements (pages 27-28, Section 4, Appendix R, Volume 7). This high pH is probably a result of contamination of the well water by the grout which is used to seal the hole. Contamination of this sort is also suggested by the high carbonate concentra- tions which appear in Table 9 of the same reference. To overcome problems related to contamination in this manner, there are two prerequisites for water quality sampling from a ground water monitoring well. First, during well development, the water in the well must be purged of 3 to 3~ times the volume of water standing in the well (i.e. water level minus borehole total depth multiplied by cross sectional area of the borehole). This extensive purging only has to be done once and may occur over several days, depending on the recharge capacity of the aquifer. Second, each time a sample is taken the well must be purged of the total volume of water contained in it. After the water level equilibrates a sample may be taken. Purging can be accomplished by blowing out the water in the hole with Nitrogen, pumping or bailing. FS-G Coal Company has agreed to the purging of all groundwater monitoring wells. All groundwater wells will undergo the complete developmental purging stage (3 to 3'z times the volume of water in the hole). Also, before taking a groundwater sample H-G will purge the hole of any water standing in the hole and then allow it to equilibrate. This practice should eliminate the problem of sample contamination. According to a preliminary guide on water quality compiled by the Division, some of the parameters in Table 9 are at suspect levels with respect to water quality. The parameters of particular interest are chlorine (in well UC-3), sulfates (wells UC-3 and UC-4), aluminum (in upper and lower coals), barium (in LC-1 and UC-2), cadmium, iron, lead and magnesium. The monitoring data for the coal seam aquifers (UC and LC wells) in particular, indicate that the water quality is substandard. It is unlikely that the water quality has been degraded by the operation. The only effect at this point would be due to the leaching of the partially completed spoil pile through the soil and into the coal. In the area of the spoil pile the upper coal group is more than 200 feet below the surface and is overlain by alternating layers of siltstone, sandstone and shale (see HG-25 of cross-section B-B' in Section 7 of Appendix R, Volume 7). With respect to hydrology, the coals are effectively isolated from the spoil pile.