joint groundwater report - Texas Commission on Environmental ...

Since 1975, when the first Class III injection well permit was issued, 34 sites have been permitted foruranium mining, six for Frasch sulfur mining, and three for sodium sulfate mining. Groundwater monitoringvaries for each of the three types of mining. The three sites which mined for sodium sulfate are currentlybeing plugged because of unfavorable economic conditions. Only two of the original six Frasch sulfur sitesare currently in operation and they are being plugged for closure. Off-site contamination from these sulfursites is highly unlikely since sulfur must be super-heated to a liquid state in order for it to flow. Anymovement away from the mine area would cool and harden the sulfur. By far, the most extensive <strong>groundwater</strong>monitoring is involved in the uranium program.Groundwater samples must be analyzed prior to any injection into a Class III well at a uranium mining site inorder to obtain background or pre-mining values. In many cases, the natural background values for these lasttwo parameters will exceed EPA drinking water standards because of the existence of the ore body itself.During the mining phase of the project, the mining companies are required to submit quarterly monitoring<strong>report</strong>s for review and approval. The <strong>report</strong>s contain <strong>groundwater</strong> analyses from within the zone being minedas well as <strong>groundwater</strong> from aquifers overlying and underlying the mined zone. Analyses includeconductivity, uranium, sulfate or chloride, and in some cases, ammonia. These control parameters are used todetect movements of mining fluids, or excursions, out of the mine area and into the monitor wells. If anexcursion is detected, additional monitoring is required and steps must be taken by the company to control themining fluid plume. A company's failure to conduct additional monitoring and control the plume is a violationof the permit, which will result in appropriate enforcement action by the TNRCC.Once mining is completed, the affected <strong>groundwater</strong> must be restored to levels consistent with baseline valuesand with previous <strong>groundwater</strong> use. Once restoration is completed, a six-month stability period must takeplace before the area is declared restored and the wells are plugged. To ensure the aquifer is restored to levelsapproved by the TNRCC, <strong>groundwater</strong> samples are taken for verification every other month by the TNRCCand the company to be analyzed in separate labs. At any time during the life of the project, water samplesmay be taken by TNRCC officials, or water samples taken by the company may be split with field inspectorsfor verification of sampling procedures, techniques, and results.In addition, the IHW Division’s UIC program regulates Class I injection wells. Class I injection wells areused to inject treated municipal wastewater and hazardous or nonhazardous liquid industrial waste below thelowermost underground source of drinking water (USDW). There are approximately 120 Class I injectionwells permitted and operating in <strong>Texas</strong>. Approximately one-half of the wells are permitted for hazardouswaste, and the other half are permitted to inject only nonhazardous waste. Likewise, 110 of the Class Iinjection wells are for disposal of on-site generated waste, and ten wells are for commercial disposal of offsitegenerated waste.The disposal of most hazardous wastes in Class I injection wells is prohibited by Land Disposal Restriction(LDR) regulations unless; 1) it can be demonstrated that the waste no longer is hazardous when it leaves theinjection zone, 2) the waste will not leave the injection zone for at least 10,000 years, or 3) the waste istreated to meet or exceed LDR standards. Most Class I hazardous injection wells have been exempted fromLDR by EPA after demonstrating either 1) or 2), above.The basic design objectives of Class I injection wells are to keep waste confined to injection zones andpermanently isolated from drinking water. The required design of Class I injection wells necessitates use ofmultiple protective barriers of steel or fiberglass well casings, and casing cements, together with continuousmonitoring of the well for development of any leaks, and annual monitoring of the reservoir, to assureseparation of injected wastes from the lowermost USDW. Class I injection wells in <strong>Texas</strong> average37