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res r M KIM �,.. ggrayy �� rtn �' � �f � `fix, '�'r?•.tiNy.K... -:.c-,r* u�:�S�u� Ntr �� RS- , r Mr. Kyle Christie January 5, 1989 Page 3 Benzene concentrations in wells BHD-1, E-5, E-8, and E-9 have decreased since [tie summer quarter, 1988 (August 26, 1988). The benzene concentration in well PR-1 .has gone from nondetectable to 6.4 micrograms per liter (ug/1), since d summer quarter, 1988. Table 2 summarizes the benzene concentrations from August 26, b88, and November 28 and 29, 1988. A contour map of November 28, 1988, benzene concentrations in groundwater is shown on Figure 1. The concentration of ethylbenzene is above DHS action levels in monitoring well E-10. The concentrations of toluene are above DHS action levels in monitoring wells E-5, E-9, E-10, and E-11. The concentrations of xylene are above DHS action levels in monitoring wells E-9 and E-10. Recovery System Water Quality Sample R-1, collected from the discharge line of the recovery system, was analyzed for BETX and TPH at Eureka Laboratories in Sacramento. Results are suminar;zed in Table 1. Complete laboratory reports are enclosed. TPH was detected in the s.mple taken from the discharge line of the recovery system. No action level has yet been established for TPH. BETX constituents are detectable in Sample R-1. However, only benzene concentrkions exceed the DHS action level. Groundwater Flow Groundwater levels at the site are being measured in each well on a weekly basis. The levels are measured with an electronic water level indicator to determine groundwater elevations relative to top of casing elevations. Since late April 1988, the groundwaVtr flow direction has been influenced by the recovery system, which has been functioning continuously since early April. A groundwater contour map for November 28, 1968, is shown on Figure 2. Table 3 summarizes the November 28, 1988, measurements. The contour map shows that groundwater flow is still being influenced by the recovery system: Conclusions Groundwater samples collected during the fall quarter 1988, show that benzene concentrations are decreasing in wells BHD-1, E-5, E-8, and 9-9;; It appears that the recovery system is working, removing contaminated groundwzier,`,"and inducing clean groundwater to flow toward the site. Monitorim, well PR-I, Uoc tted northeast of the station, now shows dissolved BETX concentrations. Because groimJtl,v:!ter flow has been strongly influenced by the recovery system (see rigure 2), rhe result, of the PR-I fall JAN 2 71989 ENVIRONMENTAL HEALTH PERMIT!SERVICES BROWN AND CALDWELL 723SSTREET SACRAMENTO.CASIPGRNIAOMt4-INZ.(9)61444-0r27 c`