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<br />Although not explicitly stated, it appears that all of the pump tests were analyzed using <br />the Cooper-Jacob Solution. This is a modification of the Theis solution in which the <br />series expression for the well function w(u) is approximated by using only the first two <br />terms of [he series. This is an acceptable solution procedure if specific limitations and <br />corrections associated with the approximation are observed. If such limitations and <br />corrections are not observed, inaccurate results may be produced. <br />Using the Cooper Jacob solution, a straight line is drawn on a semi-log plot of <br />drawdown vs time. For a variety of reasons, the full data set may not fall along a <br />straight line and the geologist must make an interpretation as to which section of <br />the data should be used in the analysis. This happens here, as most of the data <br />sets do no[ form a straight line. On many of the interpretations, data very early in <br />the test is relied upon for making an interpretation. For example, on Figure A-38, <br />an observation well used during pumping of well M-19, a straight line was drawn <br />through the first 7 minutes of a 300 minute test and the rest of the data ignored. <br />Use of such early data may be appropriate if boundary conditions or other features <br />of the aquifer system dictate, but some justification needs to be provided in each <br />case. <br />Use of the Cooper Jacob approximation requires that the match line be drawn <br />through an appropriate time interval such that the value of u (where u=rzS/4Tt) is <br />small enough that approximation of the well function series with only the first two <br />terms still yields accurate results. Generally u should be less than 0.01. This <br />limitation of the procedure does not appeaz to be observed in some of the analysis. <br />Wells PW-1, PW-3 and PW-5 all penetrate the alluvium of the Rito Seco. The <br />tests of these wells conclude the Storage Coefficient for the Rito Seco Alluvium <br />is 0.0003 to 0.0005. These aze storage coefficients we would antici~pa[e for an <br />artesian aquifer, not an alluvial aquifer under water table conditions. The <br />accuracy of this finding could have a significant impact on the degree of success <br />achievable in a remediation program. Please explain the appazent problem. <br />The Cooper Jacob solution, when used under unconfined conditions, requires that <br />a dewatering correction be applied [o the drawdown data. The original data is not <br />presented, just the time-drawdown plots. Consequently, it is unclear if <br />appropriate dewatering corrections were made. <br />Are there other aquifer conditions (for example delayed gravity drainage, partial <br />penetration in the Santa Fe etc.) that may be impacting the test results? If so, <br />how? <br />Bail Tests .. <br />There is no original data presented on [he slug tests so it is difficult to deternnine if [he <br />analysis are accurate. Given the limited information provided, we have the following questions <br />4 <br />