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w R604 :UPDATE 16 2-23-1993 { of February 23, 1993 the new wells along with MW5 have produced 3649 .4 pounds of -' gasoline range hydrocarbons, for a total 'i '. recovery of 16765 .4![ pounds . From January 13 to February 23 , 1993 „ 506 . 9 pounds of gasoline range hydrocarbons have been produced, as compared to the previous reported 419 . 5 pounds : of gasoline ` E range hydrocarbons from December 9, 1992 to January13 , 1993 , see , Table 3 and If Charts, '' Figures 6A through 6E of vapor recovery.„ F ' Vacuum Influence: ;M As was stated earlier, vapor recovery has removed the lighter" fractions of gasoline range petroleum hydrocarbons ,F£rom the soil' (through ethylbenzene) and has greatly reduced the petroleum,, hydrocarbons dissolved in the ground water beneath this site. '[ Figure 5 represents the vacuum influence generated from the t vapor recovery system as measured before obtainings depth tof ground water measurements on February 23 , 1993 . system operation: ' r i Currently a flow rate; that fluctuates between 70 cubic feet per,l minute and 94 cubic': feet per minute is being maintained throughi the two blowers that are placed in series, prior.tto exhausting k through 2 (in series) 110 gallon and one 85 gallon activated. carbon vapor scrub units . These are serviced by Exceltran and,I' Cameron Yakima for change out and rejuvenation. From January 13, '1 to February 23 , 11993 the system has operated 9861175 hours and recovered 506 . 9 pounds of gasoline range hydrocarbons (12 poundsl per day) . jM ll� METHODS AND QA/QC 4 WELL SAMPLING AND ANALYTICAL TECHNIQUES Depth to ground water and vacuum measurements were.; obtained from, all of the ground '`water monitoring wells on February 23 , 1993 .1 Depth to top of fluid and ground water measurements were obtained using a clean product water interface probe . The" probe, . lowered into the well attached to a tape calibrated in 0 . 02 foot1 intervals, signals at the contact of floating product and at the, top of ground water. The measurement is obtained. from they calibrated tape reading adjacent to a reference point on thel casing. The probe is cleaned with trisodium phosphate soapy water followed by ,,a distilled water rinse before measuring thel next well . Measurements are started at theM historically: cleannest wells and progress to the dirtiest wells'. : All depth to� ground water measurements were obtained before purging the wells for sampling. The depth to water is then subtracted from the' elevation of the casing' s reference point for a corrected ground water elevation, ,''A computer generated gradient program was not[ utilized. The more interpretive gradient map wasdeveloped by calculating the gradient from each well to all surrounding wells (difference in ground water elevations/distance between wells) , "i .e. " . MW1 to MW2,'[ MW to MW3 , MW1 to MW4, and MWI', to MW6 . Depth ; to ground water 'data from MW5 is not used, this well was installed in a slant boring and produces an anomalous high when Page 3 1