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7A - ATTACHMENT NO.3 Saltworks Proposal- Water Group Summary Report (22 January 2010) Page 30 As shown on Table 4, the wells are divided into three groups based on data completeness and well location. The first group includes the Bayport Center (Bayport) and Pacific Shores wells (first 6 wells listed in Table 4), which are documented by corresponding consultants' reports and Department of Water Resources (DWR) Well Completion reports. These wells were installed from 1991 to 2001. The second group includes eight wells on the Pacific Portland Cement site (PPC wells), which were summarized from a USGS Open-File report (Poland and Garrett, 1943) with incomplete data. These wells were installed and abandoned in the 1920s and 1940s, but are included to provide additional relevant subsurface hydraulic information. The final three wells on Table 4 are located west of the site and U.S. 101 and are documented with DWR Well Completion reports only. These three wells are presented for reference only as the analysis focuses on groundwater beneath the Saltworks site. The Bayport, Pacific Shores and PPC wells are located along the narrow strip between Saltworks and Redwood Creek and are collectively referred to as the near-site wells (Figure 5). Well depths for the near-site wells range from 250 feet to 434 feet. Non-pumping or static water levels (SWL) in the Bayport and Pacific Shores wells range from 5 to 20 feet. Water levels reported from the PPC wells are deeper, ranging from 31 to 90 feet deep. The effective screen lengths are longer for the Bayport-Pacific Shores wells (50 to 180 feet) than for the PPC wells (15 to 60 feet). Sanitary seals are installed to deeper depths (120 to 220 feet) in the more recent wells, possibly recognizing the poor quality water in the shallow groundwater system. The Bayport-Pacific Shores wells were installed with mud rotary drilling methods while the PPC wells were installed with cable tool methods. Pumping rates (Q) for near-site wells ranged between 90 pgm with 90 to 225 feet of drawdown (Bayport-Pacific Shores wells) and between 25 and 550 gpm with 45 to 169 feet of drawdown (PPC wells). Five of the six PPC wells were abandoned because of structural failures or the well was dry (PPC Well 3). Poland and Garrett (1943) reviewed and summarized the data for the PPC wells and determined that the structural failures resulted from an off-set of the casing. This casing offset could have been related to ground subsidence in the immediate vicinity of the formerly pumping wells. 3.5.1.3 Hydraulic Analysis and Aquifer Parameters Six formal long-duration pumping tests were conducted by others for the Bayport-Pacific Shores wells (GeoConsultants, 1991 b; Sohley and Maley, 1993; and Maggiora, 2001). Data from these tests were reviewed by the water team and re-interpreted to provide estimates of well and aquifer parameters, including specific capacity, transmissivity, and storativity. This hydraulic evaluation of well and aquifer parameters is summarized in Table 5 and used for estimating well yields from aquifers near the Saltworks site. Aquifer parameters control the hydraulic impacts to local and regional groundwater systems and the response to pumping, while well parameters provide the practical operating constraints of a production well. SDecific CaDacitv The specific capacity (SC) is a measure of the productivity of the well, and is computed as the discharge of the well divided by the measured drawdown (Q/s) in the pumping well at a specified elapsed time. The SC is measured in gallons per minute per foot of drawdown (gpm/ft of dd). The SC is usually reported for an elapsed time of 24 hours (Driscoll, 1986) but can be computed for shorter intervals of time. The SC normalizes 23