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MEMORANDUM <br />Ualint41-4EtiTtl HEALTH <br />CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • ueritRAL-VALILEY REGION <br />3443 Routier Road, Suite A jm .4(91,8)13pq1-5600 93 <br />Sacramento, California 95827,3098 MISS: 5600 <br />TO: All Technical Staff <br />FROM: Jon B. Marshack <br /> <br />Fresno, Redding and <br /> <br />Environmental Specialist <br /> <br />Sacramento offices Ground Water Protection <br />and Investigations Section <br />DATE: 19 July 1989 <br />(amended 14 September 1989) SIGNATURE: <br />SUBJECT: RELATIONSHIP BETWEEN CHLORINATED TWO-CARBON <br />VOLATILE ORGANIC CONTAMINANTS (VOCs) <br />One of the most common classes of contaminants found in our ground water <br />investigations are the chlorinated two-carbon volatile organics (of the general <br />formula C 2 H rn Cl n , where n = 1 to 4, and m + n = 4 or 6). This class includes the <br />following chemicals, each containing one to four chlorine atoms: <br />Chloroethane <br />1,1-Dichloroethane (1,1-DCA) <br />1,2-Dichloroethane (1,2-DCA) <br />1,1-Dichloroethylene (1,1-DCE) <br />cis-1,2-Dichloroethylene (cis-1,2-DCE) <br />trans-1,2-Dichloroethylene (trans-1,2-DCE) <br />Tetrachloroethylene (Perchloroethylene or PCE) <br />1,1,1-Trichloroethane (1,1,1-TCA) <br />Trichloroethylene (TCE) <br />Vinyl chloride (VC or Chloroethylene) <br />All have been found in landfill leachate and in ground water beneath Class III landfill <br />facilities. Dry cleaners and industries which have used solvents or degreasing agents <br />are other sites where these VOCs have been found in ground water. More than one of <br />these compounds are often found at the same site or even in the same ground water <br />sample. <br />In a number of cases, the chlorinated two-carbon VOCs found in ground water are not <br />the same ones claimed to have been used by the party originally assumed to be <br />responsible. The question then arises as to the actual source of the contaminants. <br />Knowledge of the environmental fate of members of this class of VOCs can be useful <br />in making the responsibility determination. <br />The attached figure summarizes microorganism-mediated biochemical breakdown <br />reactions linking the chlorinated two-carbon VOCs, which are known to occur in