Laserfiche WebLink
S <br /> Quarterly Group wdw Monitoring Letter Report <br /> 5491"F"Street.Santa.California <br /> GROUNDWATER MONITORING <br /> Groundwater <br /> On April 16, 1992, Aegis personnel collected measurements of the depths to groundwater <br /> in wells MW-1 through MW-6. Since January 1992, groundwater levels have fallen in all <br /> wells (Table 1, Figure 3) an average of approximately 0.47-feet, ranging from 0.46 to <br /> 0.47-feet. Based on the depth-to-groundwater measurements, the groundwater flow <br /> direction is estimated to be to the east (Figure 4) at an average gradient of approximately <br /> 0.001 ft/ft. Figure 4 is a potentiometric surface map of the shallow water-bearing zone. <br /> Previous groundwater levels are summarized in Table 1. All depth-to-groundwater <br /> measurements were made from the referenced wellhead elevations, measured to the <br /> nearest 0.01 foot, and conducted according to the Aegis standard operating procedures <br /> (SOP) included in Attachment 1. <br /> Water Sampling and Analysis <br /> On April 16, 1992, Aegis personnel collected groundwater samples from monitoring wells <br /> MW-1 through MW-6. The samples were collected according to the Aegis SOP included <br /> in Attachment 1, and delivered under chain-of-custody to National Environmental Testing, <br /> Inc., of Santa Rosa, California, a state-certified analytical laboratory. The samples were <br /> analyzed for concentrations of: a) total petroleum hydrocarbons (TPH), as gasoline, by <br /> GC/FID Method 5030; b) benzene, toluene, ethylbenzene, and total xylenes by EPA <br /> Method 8020; and, c)TPH, as diesel, by GC/FID Method 3510. The analytical results are <br /> summarized in Table 2. The analytical reports and chain-of-custody form are included in <br /> Attachment 2. Concentrations of TPH, as gasoline and diesel, and benzene reported in <br /> Table 2 are also shown on Figure 5. <br /> 9p-099B.QMR -2- <br />