Laserfiche WebLink
Comparison of Ground Water Quality to Water Vse Standards. SCC has compiled a Liat of • <br />ground water standards for agricultural uses (Table 5). This list is composed mostly of <br />Colorado Department of Health (CDON) ground rater standards as of April 1996, although <br />other agency standards have been used if the CDOH has no agricultural standard for a <br />particulaz parameter. Table 5 has footnotes to indicate the source of each rater quality <br />standard. <br />Table 6 provides a comparison of ground rater quality to agricultural standards. This <br />Paradox database generated table does not include the units of concentration (mg/1 or <br />ug/1) for each parameter. The units used for each parameter axe the acme ae those listed <br />on the standards table (Table 5) and are also the same as those used in the rater quality <br />reports. The frequency column on Table 6 indicates the number of exceedencea out of the <br />total number of samples (i.e., 1/2 indicates one exceedence out of two samples). Helow is <br />a summary of standards that were exceeded. Given in pazenthesia ie the source and use of <br />each standard. <br />Parameter Number of Wells <br />iron (CDOH, irrigation) 1 • <br />manganese (CDOH, irrigation) 5 <br />di9solvad solids (VSEPA, irrigation) 7 <br />sulfate (California, irrigation) 11 <br />In addition, one sav¢+le had a cadmium value that ran less than an elevated detection limit <br />(20 ug/1 vs. a normal detection limit of 2 ug/1) which was higher than the CDOe standard <br />o£ 10 ug/1. Likewise, one sample had a lead value that ras less than an elevated <br />detection limit (200 ug/1 vs. a normal detection limit of 20 uq/1) which was higher than <br />the CDOH standard of 100 ug/1. The cause of these elevated detection limits vas a <br />decision by the laboratory to di lots the samples prior to analyses in order to reduce the <br />effects of interferences (primarily, high salinity). SCC is currently in discussion with <br />the laboratory to either reduce the dilution factor or to qo to a method with a lower <br />detection limit. <br />In the Probable Hydrological Consequences (PHC, Tab 17) section of the Yoaet Mine PAP, <br />predictions were made as to the expected TDS increases to be obsezed at various <br />monitoring wells. The following table outl inea these predictions along with this yeaz~s • <br />observed average values. <br />6 <br />