Laserfiche WebLink
<br />7A - ATTACHMENT NO.3 <br />Saltworks Proposal- Water Group Summary Report (22 January 2010) Page 35 <br /> <br />. Transmissivity values range between 2,100 and 5,954 gpd/ft, average 3,790 <br />gpd/ft, and could be as low as 268 gpd/ft in certain areas underlying the site. <br /> <br />. Hydraulic conductivity values range between 14.6 and 76.4 gpd/ft2 and average <br />38.4 gpd/ft2. <br /> <br />. Storativity values range between 2.57E-04 to 9.78E-05 and average 4.66E-04. <br /> <br />. Well specific capacity values range between 1.15 and 2.91 gpm/ft of dd, and <br />could be as low as 0.46 gpm/ft of dd in certain areas underlying the site. <br /> <br />. Pumping test data indicated the presence of barrier boundaries, indicating <br />potential limits to the extent and sustainability of the freshwater aquifer(s) <br />encountered in near-site wells. <br /> <br />Collectively, these hydraulic data indicate confined freshwater aquifers of moderate <br />permeability beneath the site, but with potential significant limitations in extent, well <br />yields, and sustainability. <br /> <br />3.5.1.4 Ambient Groundwater Quality <br /> <br />The OMB Supply Report provides a brief discussion of groundwater quality in the San <br />Mateo Plain subbasin. The report indicates that local groundwater is hard and in some <br />cases, that concentrations of total dissolved solids (TOS), chloride, iron, and manganese <br />are in excess of their respective primary or secondary drinking water standards. The <br />OMB Supply Report concludes that blending or treatment would be required to meet <br />drinking water standards and indicates that reverse osmosis treatment would be <br />provided onsite if groundwater supply were used as potable supply for the project. <br /> <br />Additional information regarding local groundwater quality issues is provided in the EKI <br />November 1, 2006 draft technical memorandum, "Summary of Preliminary Investigation <br />of Groundwater Extraction Opportunities." Table 5 of the memorandum presents <br />selected water quality parameters from selected wells in the subbasin. <br /> <br />For this evaluation, available groundwater quality data were compiled from the Pacific <br />Shores and Bayport wells described in Table 4. Table 6 summarizes data from five <br />samples collected in the early 1990s from four wells and contains the constituents <br />analyzed (including major ions, minor ions, physical parameters, and trace ions), the <br />respective laboratory detection limits, the analytical results from each sampling, and the <br />relevant drinking water standard. Shading is used to highlight the analytical results <br />indicating an exceedance of drinking water standards. The wells cited in Table 6 are <br />screened generally at depths of 120 to 330 feet; accordingly, the water quality data <br />represent freshwater aquifers underlying the project area at moderate depths. <br /> <br />Consistent with the discussion in the OMB Supply Report, constituents exceeding the <br />drinking water standard are shown for chloride, iron, manganese, and TOS (and <br />associated electrical conductivity). The sample from Well 2 indicates a sulfate <br />concentration at the drinking water standard of 250 mg/L. <br /> <br />28 <br />