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<br /> <br />Quality <br /> <br />Characteristics <br /> <br />There is a tremendous range of ground water qua Ii ty because <br />of the cham i ca I charactar i st i cs of recharge water and the <br />geologic formations through which ground watar tra.....els. Some <br />ground water aquifers yield water nearly as pure 35 disti lIed <br />water. Others may be sa I tier than seawater and st i II others <br />may be natura II y rad i aaet i va or character i zed by some <br />particular chemical constituent or combination of them. <br />Differences in ground water qual ity are often predictable <br />from geologic and geochemical knowledge. <br /> <br />Aggravating Circumstances & Consequences <br /> <br />I n Co I crado the most common natura I water qua II ty prob 1 ems <br />are hardness and sal inlty because of minerals dissolved in <br />the water. Hard water can be softened with chemical <br />treatment. The second most preva lent s i tuat i on, and an <br />increasingly serious one as the state's I imited water <br />supplies are called upon to meet the demands of growth, is <br />the contalnination of good ground water with sewage, <br />industrial and agricultural chemicals and other wastes. <br /> <br />Malfunctioning sewage disposal systems, seepage from dumps <br />and landf! 115, Improper waste disposal methods, minerai <br />exploration and production are jeopardizing drinkable water <br />supp I I es and i ncreas I n9 the cost of treat i ng them before they <br />can be used. Depending upon the type and volume of <br />contaminants. rehabi I itatlon of a polluted ground water <br />supply may take several years or an undetermined amount of <br />time--if It can be achieved at all. <br /> <br />Mitigation <br /> <br />A thorough understanding of the ground water system and its <br />relationship to human activities is the first step in <br /> <br />protecting water quality, mini;nlzing treatment costs and <br />providing people with safe water .for drinking and growing <br />food. <br /> <br />Proper construct I on, operat i on and ma i ntenance of sewage <br />disposal systems, neutralizlngor isolating harmful chemicals <br />prior to disposal and revised manufacturing processes are <br />basic protective measures. <br /> <br />Land Use <br /> <br />While land uses which contaminate ground water wi 11 always <br />exist, hydrogeologic investigations are fundamental to <br />managing both 13nd and water and ensuring their value. <br /> <br />Case History <br /> <br />In the 1940ls and 50's, the U.S. Rocky Mountain Arsenal in <br />western Adams County deposited a complex mixture of chemical <br />wastes from the manufacture of pesticides, herbicides, and <br />some chemical warfare agents into unlined holding ponds. It <br />al so injected wastes into subsurface zones through a deep <br />disposal well. i-1ore than 30 square mi les of a shallow fresh <br />water aquifer were contaminated by toxic substances (aldrin <br />and dieldrin) in the vicinity of the ponds. <br /> <br />Losses from this disposal of toxic wastes over a permeable <br />ground water zone exceeded $2,165,000, Including payments to <br />ranchers and farmers for well contamination and crop losses. <br />Adequate geological investigations could have anticipated the <br />prob I em and Ii n I ng of the d I sposa I ponds cou I d have prevented <br />seepage contamination. <br /> <br />'wastes also were injected Into the subsurface zones through a <br />deep d i sposa I we II. Mil d earthquakes recorded in the <br />vicinity of the well were attributed to deep well injections. <br />The earth tremorS;Jera not exper I enced pr ior to I nJect I on and <br />gradually ceased after injection disposal was terminated. <br /> <br />In June. 1978, a U.S. Senate subcommittee approved $6.5 <br />mill ion to continue cleanup -.....ork at the arsenal. <br /> <br />23 <br />