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Ya 1•, Extraction of water from KW-1 had been discontinued at least one week prior to our measurements to allow for equilibration of groundwator hydrostatic. conditions. Figures 2 and 3 were drawn using the measured elevations and depict a south-southwesterly gradient. The groundwater elevation in M6--1 (taken on 2/27/90) was not used in generating Figur.: 3, as the pump had been removed only one hour prior to measurement (to allow for access of the sampling bailer) and the water level had not reached equilibrium. The measured value indicated -22.31 feet below sea level and did not, in our opinion, represent static cond_tions. Using this value would have created an artificially depressed cone or hole or. the gradient contour map shown in Figure 3. The groundwater gradient beneath the Holt Brothers facility trends south- southwesterly at an average inclination of 25 feet/mile, or less than one degree from horizontal. The minor variation in gradient shown between Figures 2 and 3 may be caused by tidal influences and by fluctuating water levels from nearby river sloughs and the Sap. Joaquin River. 1..0 DISCUSSION OF RESULTS r • The chemical analyses of water from the six monitoring wells indicates that groundwater contamination is tastrieted to the areas immediately around MW- 1 and around MW-2. The remaining wells do not show any detectable i_vels of the tested contaminants. In light of the fact that Bio National Corporation has been extracting groundwater from MW-1, the overall reduced levels of hydrocarbons revealed in the analysss may be a direct result of this extraction, Levels of hydrocarbons in MW-2 increased only slightly and purgeable volatile organic compounds such as benzene have dropped below detection limits, possibly by natural biogenic degradation (Table I). To put into perspective the effect that the detected groundwater contaminants may potentially have on groundwater quality, it .is helpful to compare the analytical results with various regulatory criteria and standards. Bl:nNTL.H2O 4 April, 1990 i