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CLEARWATER" <br /> G. R O U P, I N C. <br /> concentrations were below the detection'limit of 0.06 ppm, and xylene <br /> concentrations were below the'detection lim t of 0:12 ppm. <br /> The soil generated during well installation (a proximately 1-2 cubic yards) is <br /> stockpiled at the site-on Visquene. .Because thes analytical data _indicates no <br /> detected concentrations of hydrocarbons, Clearwater requests permission'to <br /> spread the soil.on the ground surface rather than dispose of it at.a landfill. <br /> Mr...-Dale Ramey has given his'approval to do so, contingent upon receiving <br /> permission.from the San Joaquin County Public Health Services,. . <br /> Environmental Health.Division (PHS).. <br /> Groundwater Gradient <br /> _ ;o _, . . <br /> In a recem phone..conversation, you mentio:^ <br /> ed that the groundwater <br />` gradient shown in the quarterly report was the opposite direction to the <br /> gradient at other nearby,sites: 'Oh October 18 '1995 the Clearwater field. <br /> geologist ie-surveyed the tops of casing on the three monitoring wells. I.have <br /> reviewed.his survey data and'water level data, and the gradient (based upon <br /> those three data points) is consistent with that indicated"in the:last report. <br /> The first round of monitoring,conducted in ebruary 1995, indicated an ' <br /> opposite'gradient.' <br /> For the-followin9.reasons I'.re recommend mend n <br /> o further a ' <br /> e coon 'r <br /> e ardin <br /> the <br /> g g- <br /> groundwater gradient•until additional wells have been in <br /> • The gradient".(based",upon the existing three wells) is very fiat; the. , <br /> maximum difference in . dwater elevations during an <br /> monitoring . <br /> .event was 0;06 foot; and it has been only. ;04 foot during two of'three <br /> 'monitoring events <br /> • The three 'wells in question are in1 <br /> c osexi <br /> o mi to one another , <br /> (maximum distance between any two wes'is approximately 75_ feet) <br /> • The arrangement of the wells (a "dogleg" is not the optimum geometry <br /> with which-to calculate the gradienf base upon only`three data points. <br /> Because-more work will be conducted- at-thesite 'to implement the <br /> workplan, I recommend .that the groundwater gradient is re=evaluated after, <br /> additional data points have been established. . <br />