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Kennedy/Jenks/Chilton <br /> Mr. Wil Smith <br /> Lincoln Properties Ltd. <br /> 9 January 1991 <br /> Page 2 <br /> benzene, toluene, and xylenes; however, gasoline odors were detected by field <br /> personnel during soil sampling from the surface to a depth of approximately 32 <br /> feet. Laboratory analysis of groundwater samples collected from MW1 detected 990 <br /> ppb of total hydrocarbons, 32 ppb of benzene, 47 ppb of toluene, and 43 ppb of <br /> xylenes . These results indicate that an unauthorized release had probably <br /> occurred at this site. The soil and groundwater samples, however, were not <br /> analyzed for any other compounds and, in SES's 1990 investigation, MW1 could not <br /> be sampled because it had gone dry. <br /> Chevron MW1 , which appears to be located within the bounds of the former <br /> underground storage tank excavation, is of critical importance to the Chevron <br /> site investigation because it had previously indicated the presence of gasoline- <br /> type contaminants in the groundwater. With this site-specific data not currently <br /> available, it is unknown whether petroleum hydrocarbon contamination of the <br /> groundwater still exists at this monitoring location, whether residual <br /> contamination is now trapped in the unsaturated zone due to the recent decline <br /> in water levels, and/or if the previously detected contamination has now migrated <br /> offsite. To help resolve these issues, a replacement monitoring well located <br /> adjacent to and downgradient from the former underground tank location is <br /> recommended. <br /> To date, analytical data obtained during K/J/C's current investigation and <br /> Leedshill -Herkenhoff, Inc. 's previous investigation of the Lincoln Center <br /> property does not support Chevron's contention that the detected quantity of 1,1- <br /> DCA in Chevron MW5 is a result of activities at the dry cleaning establishments. <br /> K/J/C's ongoing investigation involves lateral and vertical definition of soil <br /> and groundwater contamination caused by tetrachloroethylene (PCE) and its <br /> breakdown products. This investigation has included installation of fifteen (15) <br /> monitoring wells and extensive testing of soils and groundwater. Figure 2 shows <br /> the locations of these monitoring wells and soil borings as well as groundwater <br /> contours based on depth to water measurements taken on November 29, 1990. As of <br /> the date of this letter, 1 ,1-DCA has not been detected in any of the soils or <br /> water samples collected and analyzed during the Lincoln Center investigation._ <br /> This includes soil and groundwater samples from the soil borings and monitoring <br /> wells soil samples collected adjacent to floor drains located directly beneath <br /> the floor slabs at the dry cleaning establishments soil samples collected <br /> beneath the sewer lines servicing these dry cleaning establishments and sewage <br /> water samples. Furthermore, 1 ,1-DCA is not a breakdown product of PCE. However, <br /> 1, 1-DCA is a solvent which is used as a paint, varnish, and finish remover and <br /> metal degreaser, and, therefore, it would not be uncommon for this compound to <br /> be associated with a gasoline service station facility. <br /> Based upon our investigation to date, a confirmation sample should be obtained <br /> from Chevron MW5 to verify the presence of 1, 1-DCA in the groundwater. If this <br /> sample verifies the presence of this compound, it is our recommendation that <br />