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j where b=the thickness of the aquifer r . . W(u,r/B), s, 1,/u, and t are the parameters taken from the match point of.the . ploted data and type curves. Figures 3-6 and 3-7 are log-log plots of the data-from the pumping wells during each aquifer test. Pumping well MW-DIS-8S discharged water at 3 gpm, whereas pumping well MW- DIS-8D was pumped at 2.1 gpm. The drawdown in the wells is compared with a number of different r/B values to arrive at the most appropriate curve-matching scenario. '"Storage. coefficients were not calculated because there was no observable drawdown. Transmissivities calculated using the Hantush method are 20.3 Oday and 11.6 ftp/day for MW-DIS-8S and MW-DIS-8D, respectively. Assuming .a well screen of 20 feet in the A Zone and 10 feet in the B Zone,the hydraulic conductivities are 1.0 ft/day for both zones. Groundwater Modeling A finite element groundwater flow model was developed for the Disco site. The model covers an area of 10,000 feet by 10,000 feet and consists of 5 layers representing the hydrostratigraphic layers present at the site. The model consists of 6,672 nodes and 13,274 elements using the finite element code "Microfem" version 2.45. Based on typical amounts of groundwater recharge that would occur in the Stockton area, groundwater recharge from the surface was estimated to be 1 inch per year. Aquifer transmissivities for the A and B Zones developed from the analysis of pump testing data were applied to the multi-layer stratigraphic system consisting of five layers. The properties of the layers in the model are presented in Table 3-1. The model was calibrated to approximate the existing groundwater gradient in both" a horizontal and vertical direction. Based on groundwater level records, the typical horizontal component of the groundwater flow gradient is toward the northwest. However, this gradient is very small, about 0.001 ft/ft., Pumping from large production wells in eastern Stockton has historically produced a large cone of depression. The Disco site is located on the periphery of this regional depression, which appears to have a relatively flat gradient., There has been evidence of a downward gradient on the site that has not correlated with local production well pumping by Del Monte's adjacent Plant 33 to the north of the Disco Site. The downward vertical gradient at the Disco site is likely related to the regional pumping and the large cone of depression to the east and local recharge. 1 � sF010030982.DOC 3-11