C153701 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I Section 2 - Study Area Descriptions TABLE 2.6 REPORTED WATER QUALITY - OTHER VARIABLES (mgll as ion except as noted) Variable Recommende Average Maximum Minimum d Maximum Level Alkalinity - 328 360 300 Boron - 0.18 0.23 0.14 Calcium, as CaC03 - 866 1050 750 Hardness, as CaC03 - 1026 1210 860 Magnesium 125 61 73 50 Molybdenum - ND ND ND Phosphate - 0.1 0.12 0.07 Sodium 20 154 170 140 Specific Conductance, - 2373 2700 2100 (ohms) SDW A Standards are classified by either primary or secondary standards. Primary standards are rigidly enforced by the Colorado Department of Public Health and Environment. Violations of primary standards can result in a mandate from the Health Department requiring an alternative drinking water supply. Secondary standard violations require only public notification that the standard has been violated. Water quality parameters that exceed MCL's are highlighted. The undesirable water quality of the City's supply is believed to have been caused in part by agricultural activities in the surrounding area. The numerous irrigated farms and feedlot operations located south and west of the City are considered to be two primary reasons that nitrate, TDS and sulfa,te concentrations in the water supply are high. The elevated manganese concentrations are presumed to result from natural conditions in the aquifer. Water Quality Variables of Concern 1. Adjusted gross alpha: Naturally occurring alpha particles have exceeded the proposed SDW A MCL. Adjusted gross alpha concentrations averaged about 10.5 pCiII, which is close to the 15 pCi11 MCL. The concentration of one sample was 27 pCill, which was in violation of the proposed standard. The minimum reported concentration was 0 pCi/I. 2. Nitrate: Average nitrate concentrations in 1993 were around 8 mg/L as N. The SDWA MCL for nitrates is 10 mgll as N. The concentration from one MONTGOMERY WATSON Page 2,9