AgdaPkt 2010-02-01 clsd and regular

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7A - ATTACHMENT NO.3 Saltworks Proposa/- Water Group Summary Report (22 January 2010) Page 31 hydraulic information and allows comparisons between wells and within one well at various times during the life of the well. SC decreases with higher discharge rates and over time as the well ages. The SC can range several orders of magnitude (0.01 to 100s of gpm/ft of dd). In general, SCs less than five indicate low-yield wells that produce small amounts of water for domestic, small industrial, and some agricultural uses. SCs greater than five can yield wells that produce 100s of gpm. The geometric mean SC values range between 1.31 gpm/ft of dd (Bayport-Pacific Shores wells) and 2.24 gpm/ft of dd (PPC wells). Table 5 shows the 24-hour SC (Q/s) of these more recent pumping tests; Table 4 shows the SC (Q/s) data for the PPC wells. The 24-hour specific capacities (SC24) on Table 5 range between 0.46 and 2.91 gpm/ft of dd. The SC of Bayport NO.1 is anomalous (at least one-order of magnitude lower than the remaining SC) and may represent well screens in a fine-grained portion of the aquifer, incomplete well development, and/or an improperly designed well. If Bayport No. 1 is removed from the analysis, the range of SC values for the pumping tests narrows (1.15 and 2.91 gpm/ft of dd) and is within the same range (1.31 and 2.24 gpm/ft of dd) as the PPC wells (Poland and Garrett, 1943) summarized in Table 4. Because of the anomalous hydraulic data, the Bayport No. 1 pumping test data were not considered further in this analysis. All of these SC values indicate relatively low-yield wells. Transmissivitv The transmissivity (T) is the rate at which water is transmitted through a unit width of the aquifer under a unit hydraulic gradient, and is measured in gallons per day per foot (gpd/ft). The T value is a property of the aquifer and the transmitting fluid and is estimated from constant rate pumping tests. T values are estimated from time- drawdown, recovery, or distance drawdown plots (if responsive observations wells exist). Four of the six pumping tests summarized in Table 5 have two observation wells; the two tests conducted on Bayport NO.1 were single well tests. Time-drawdown and recovery plots were constructed for all the pumping tests while distance-drawdown plots were constructed for each of the Maggiora Bros. pumping tests. Analyses of these plots are summarized in Table 5. T values from the Time-drawdown and distance-drawdown data are combined in the Drawdown column on Table 5 with notations for the distance- drawdown data in the Duration column. The T values for the Pacific Shores wells range from 2,626 to 5,193 gpd/ft from the time- drawdown plots, from 1,028 to 3,199 gpd/ft from the recovery plots, and from 2,100 to 5,954 gpd/ft from the distance-drawdown plots. The recovery data typically underestimate the T value, resulting in the slightly lower values. Considering that aquifer transmissivity can vary in excess of 13 orders of magnitude in a relatively small area, the range of computed T values (1,000 to 6,000 gpd/ft) is judged relatively narrow and considered applicable to the Saltworks site. The geometric means for T values for the time-drawdown, recovery, and distance-drawdown analysis are 3,790 gpd/ft, 1,870 gpd/ft, and 3,680 gpd/ft, respectively. In addition, the pumping tests conducted by Bohleyand Maley (1993) and Maggiora (2001) provided an internally consistent family of parallel time-drawdown curves representing the same transmissivity for each observation well. 24