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beneath the city, then the groundwater <br />contamination may threaten the potable-water <br />supply. <br />When evaluating if there is any such threat to <br />the potable-groundwater supply, relevant <br />factors to consider may include the following, <br />as well as other potential factors: <br />• what groundwater zone(s) are used <br />• what groundwater zones are <br />contaminated <br />• what the degree and extent of the <br />groundwater contamination is <br />• the hydraulic connection between the <br />potable-groundwater supply and the <br />contaminated groundwater <br />• how much is known of the location of <br />existing local water wells <br />• proximity of existing and planned <br />potable-water wells to groundwater <br />contamination <br />• the design of those potable-water wells <br />and the integrity of those wells against <br />contamination <br />• potential for future water-well <br />installations outside the MSD potable <br />water-use prohibition <br />• the chemical and physical properties of <br />the groundwater contaminants <br />Considering these factors, it may become <br />apparent that MSDs can be appropriately sited <br />anywhere within the city, or only within certain <br />areas of the city, if at all. There may be ways <br />to shore up any uncertainties in the <br />appropriateness of MSDs by placing particular <br />information or action requirements on the <br />applicants. <br />lrrigation and industrial water <br />SOUI"C@S <br />If the groundwater is used for non-potable <br />water in the vicinity of the MSD property, the <br />TCEQ is not prohibited by statute from <br />requiring the person to investigate and <br />remediate the groundwater to address those <br />non-potable considerations. Examples of non- <br />potable groundwater use include irrigation of <br />lawns, watering pets and livestock, and <br />industrial process or cooling water. Historically, <br />the TCEQ has typically applied its protective <br />concentration levels for potable-water use to <br />such non-potable uses of groundwater. <br />Outcrops of Major Aquifers in Texas <br />I LegMd <br />comd.s <br />~.~.w. <br />; <br />~ Major A <br />r <br />lf <br />B N <br />w~a <br />. <br />_.i <br />qu <br />e <br />s <br />ame <br /> <br />~ <br />CARRQO <br />' <br />~ <br />Envwaos <br />.y. <br />EDNW2DSTRMATY <br />cuLF cwsr <br />H,ECo saSoN <br />ocnLuu+ <br />PHCOS VAILEY <br />SEYMWR <br />~ iaNm ~ <br />o 100 200 aoo 400 <br />n~~s <br />Additionally, pumping of <br />groundwater for non-potable <br />use can spread the existing <br />groundwater contamination. <br />The frequency of non- <br />potable groundwater use in <br />the area might give an <br />indication of whether the <br />municipality might prefer the <br />MSD to cover the full extent <br />of groundwater <br />contamination, or to provide <br />the necessary insight into <br />the appropriate scope and <br />scale of an ordinance <br />prohibiting municipal <br />groundwater use or a <br />restrictive covenant. <br />MSD Management <br />Considerations <br />Figure 2. Outcrops of major aquifers. <br />• the local (and possibly regional) <br />hydrogeology (aquifer recharge, <br />groundwater flow, aquifer <br />interconnectivity, etc.) <br />MSDs frequently bring up questions regarding <br />management, some of which might not be <br />unique to, or a true consequence of, an MSD. <br />GI-326 Page 6 <br />r <br />_ _ 1 <br />