Orange County NC Website
Browse       Search
26 <br /> Water Quality Assessment <br /> Objectives <br /> • To determine the degree to which water supply wells are protected against contamination. <br /> The evaluation will identify any deficiencies with the well heads with respect to proper well <br /> protection components (seals, vents, casing height) and with location of the wells. <br /> • To determine the quality of water at each well supplying the homes. Wells will be tested for <br /> parameters that are related to health risks as well as for aesthetic qualities. Wells that are no <br /> longer used for drinking water supplies are not included in the survey. <br /> Methodology <br /> All households in the survey area who completed and returned an application were included in the <br /> assessment. Of the potential 25 wells in the defined area, 11 applications were received. <br /> The sampling collection included analyses of <br /> • Total and fecal coliform bacteria <br /> • Inorganic chemicals <br /> • pH and turbidity <br /> • Pesticides <br /> • Volatile organic compounds and Petroleum <br /> • Nitrates and Nitrites <br /> Chain of custody for the samples was assured by direct delivery of all samples to the NC Laboratory <br /> of Public Health in Raleigh. As lab analyses were reported from the lab, the results were entered <br /> into a master spreadsheet. <br /> Water Sampling Results <br /> Bacteriologic Quality <br /> Of the 11 wells sampled: <br /> • one sample showed presence of total coliform bacteria <br /> • two samples showed presence of fecal coliform bacteria <br /> • eight samples tested negative for coliform bacteria <br /> Coliform bacteria, while not pathogenic in and of itself, is used as indicator bacteria for the <br /> presence of harmful bacteria. The presence of coliform bacteria indicates that surface water <br /> contamination is present in the well, either through a shallow, unprotected vein of water(generally <br /> less than 60 feet from the ground surface), or from an inadequate length of casing or other well <br /> construction deficiency. For drilled wells, the casing is the metal pipe that extends from the ground <br /> surface and goes into solid rock (bedrock) to seal out the shallow groundwater, which is poor in <br /> quality. Hand-dug wells and bored wells rely on shallow groundwater and commonly contain <br /> coliform bacteria. Shallow wells are also more prone to going dry or getting muddy during extended <br /> periods of drought. For these reasons, current Orange County well construction standards require at <br /> least 63 feet of casing on all new drilled wells. <br /> Page 5 of 11 <br />