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Margaret Lagorio <br /> From: janes.elizabeth@epamail.epa.gov <br /> Sent: Tuesday, December 24, 2002 11:08 AM <br /> To: hightechted@jps.net <br /> Cc: fitzgerald.shannon@epamail.epa.gov <br /> Subject: underground injection control regulations and drinking water standards <br /> Mr. Finucane: <br /> The Underground Injection Control (UFC) regulations promulgated per the <br /> U.S- Safe Drinking Water Act prohibit the use of subsurface disposal <br /> systems, including septic systems, for the disposal of substances which <br /> may contaminate underground sources of drinking water. Solvents are of <br /> particular concern because of their mobility in saturated environments. <br /> While residential septic systems are generally not subject to the <br /> requirements, the presence of acetone, benzene and MTBE in a septic tank <br /> indicate some industrial use of that septic system, making it subject to <br /> the requirements beginning at 40 CFR part 144 . Part 144.27 authorizes <br /> EPA to request whatever site characterization may be needed to determine <br /> if the discharge posed or poses a risk to receiving aquifers. The <br /> federal maximum contaminant levels or MCLS for drinking water are the <br /> primary standards used for compliance assessment (see <br /> http://www-epa.gov/safewater/mcl.html) , but the UIC regulations do not <br /> preclude EPA from using any other applicable health standards, so in <br /> California we also look at the California drinking water standards and <br /> health advisory levels (see <br /> http://www.dhs.cahwnet.gov/ps/ddwem/chemicals/chemindex.htm) , and RCRA <br /> (40 CFR part 261.. ) <br /> When investigating such sites, the material in the injection well is <br /> considered a relic of past disposal practices. Because injection wells <br /> are constructed to percolate, it is not safe to presume that <br /> contaminants, particularly soluble contaminants, will be held entirely <br /> within the injection well. Each site has to be evaluated against a list <br /> of factors including the depth and likely time of travel to the nearest <br /> drinking water aquifer, the volume of contaminant discharged, and the <br /> years of discharge, in order to determine how much sampling is necessary <br /> to ascertain the degree of soil and ground water contamination, and <br /> relative risk to drinking water wells. <br /> I am going on maternity leave within the week. For additional <br /> discussion regarding this matter, please contact Shannon Fitzgerald at <br /> (415) 972-3525 or fitzgerald.shannon@epa.gov. <br /> 1 <br />