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<br />- .I...l - <br /> <br />,. <br /> <br />these facilities on ground water, the vast majority of such <br />sites produce liquid leachates, making it all but certain that <br />such facilities are major sources of ground water pollution. <br /> <br />A similiar situation obtains at pits, ponds, and lagoons-- <br />usually grouped and referred to as surface impoundments--that <br />receive both hazardous and non-hazardous wastes. The recently <br />completed Surface Impoundment Assessment (SIA) surveyed the <br />numbers and location of surface impoundments, and estimated their <br />potential effects on ground-water quality.81 The SIA defined <br />impoundments to be any significant man-made or natural depression. <br />used to treat, store or dispose of waste (agricultural, mining, <br />oil and gas, municipal and industrial). The study was not field- <br />verified and so is subject to error. Still, it presents an initial <br />working estimate of surface impoundments and their potential impact <br />on ground water. <br /> <br />The study identified a total of 181,000 surface impoundments. <br />Most of them are unlined. About 40% of municipal and industrial <br />impoundments are located in areas with thin or permeable soils, <br />over aquifers currently used for drinking, or that could be used <br />for drinking. Only about 7% of all sites appear to be located <br />so as to pose little or no threat to ground water. It is evident <br />that ground water protection was rarely, if ever, considered <br />when these facilities were sited. <br /> <br />Septic systems also discharge high voiumes of waste to <br />ground water. In some parts of the country they are among the <br />most frequently reported sources of contamination. Approximately <br />20 million American households, or 29 percent, use this type of <br />on-si te. waste dtsposa-l--system-.----Assuming- a- 50-gallon-daily -dis-- <br />charge per capita, household septic tanks handle about 3.5 billion <br />gallons of waste per day.91 The primary health hazard is the <br />introduction of pathogens-and nitrates to ground water, but the <br />presence of organic cleaning solvents is of growing concern as <br />well. There is little useful information on ground-water contami- <br />nation from commercial or industrial septic systems. <br /> <br />Other practices may account for up to two-thirds of the <br />incidents of ground-water contamination. lQ/ Improper use of <br />pesticides and fertilizers, coating of roads with contaminated <br />waste oils, use of highway de-icing compounds, leaking underground <br />storage tanks and pipelines, accidental spills and "midnight <br />dumping," abandoned wells, over-pumpage and excessive drawdowns, <br />and poorly managed artificial recharge have all caused ground- <br />water contamination. Many of these practices go on with little <br />recognition or concern for their potpntial impact on ground-water <br />quality. . <br /> <br />0105 <br />