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2 <br /> Water Quality Site Assessment -2- lr� S November 1992 <br /> 2. Collect filtered ground water samples, and ensure that no sample mration takes <br /> place. At each sampling location, collect a sample from all hydrogeologic zones <br /> identified beneath the water table. Analyze each sample for the following dissolved <br /> constituents and parameters: <br /> Title 22 Metals As, Ag, Ba, Be,Cu,Cd, Co, Cr (Total), Cr*6, Hg, Mo,Ni,Pb, <br /> Se, Ti, V, and Zn; <br /> General Minerals Ca, Mg, Na, K, Fe, Al, Mn, SO4, Cl,NO3, and alkalinity; and <br /> General Parameters EC, pH, and TDS. <br /> [Other constituents may need to be added, based on knowledge of past site activities.] <br /> 3. Calculate the mean and the standard deviation of the mean dissolved concentration <br /> for each constituent and parameter in each hydrogeologic zone to establish site-wide <br /> background concentrations for the different ground water zones. <br /> Constituent Assessment in Assessment Areas for Ground Water <br /> 1. For each assessment area, determine the dissolved ground water concentrations for <br /> all general minerals and parameters, and for those Title 22 Metals that are suspected <br /> constituents of concern,based on past industrial and waste management activities <br /> for that area. [Other constituents may need to be added,based on knowledge of past site <br /> activities.] <br /> 2. Statistically compare each constituent's dissolved concentration from each assess- <br /> ment area for each hydrogeologic zone with each constituent's background ground <br /> water concentration for that ground water zone. <br /> a. If an assessment area ground water concentration for a constituent in a specific <br /> ground water zone is less than the background ground water concentration for <br /> that constituent in the same ground water zone, then the constituent is not a <br /> constituent of concern for water quality. No further action is required for that <br /> constituent in that ground water zone, provided that the concentration does not <br /> present a risk to human health. <br /> b. In an assessment area,if the concentration of a constituent in a ground water <br /> zone is greater than the background ground water concentration for that con- <br /> stituent in the same ground water zone, then the constituent is a constituent of <br /> concern for water quality. This means that ground water degradation has oc- <br /> curred and ground water remediation may be necessary. In addition,if the <br /> same contaminant is present in overlying soils, contaminant breakthrough has <br /> occurred and no attenuative capacity is available for that constituent within <br /> overlying soils at that site. <br />