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3 <br /> r.� <br /> `y <br /> R,9vai Oak Savings& Loan <br /> Knal Remediation Plan <br /> Addendwn #11 <br /> Groundwater Remediation <br /> Page: S <br /> 4.0 GROUND WATTS R QUALNY <br /> A water sample eras taken from MW-2 on i:.-12-90, in order to characterize dic <br /> background Ground `Nater Quality at this site. This sample was tested for Coliforni <br /> Bacteria, Priority PoI Metals, Purgeable Organics (EPA Method 624) and Semi- <br /> Volatile Organics (EPA Method 625). Except for low level presence of some Priority <br /> Pollutant Metals, all test results were Non-Detect. <br /> Presence of Arsenic, Chrome, Copper, bead, Silver, Vanpdium are Zinc was detected <br /> in the sample. Concentrations of these metals are well below acceptable;3rinkingwater <br /> standards (see table). The low level presence of these metals in the Shallow Ciro-and <br /> Water at the site is due to natural background conditions, and no way results from l)a,c <br /> industrial activities at the Royal Oak Site. <br /> The Shallow Ground Water at this site has been contaminated by bast leak,- of <br /> gasoline from underground storage tanks. The tanks were removed some time ago. <br /> Gasoline contaminated soils werc excavated and remediated in September of 1990. <br /> Monitoring Wells installed by others at this site had detected unacceptable levels of <br /> Benzene in the Ground Water in the past. (See'rable...j. . <br /> Our recent installation and sw- np?ing of Monitor Wells hff-5,6, and 7 show that there <br /> may be some Benzene contamination remaining in the Ground Water at the site. <br /> Our recent sampling of the discharge waters from pump testing MW-5 showed.Non- <br /> Detect for Gasoline and BTXE. These waters were stored in a 10,000 Gallone Swing <br /> Tank at the site. <br /> Our receant sampling of NIW-2,4,5,6, and 7 showed Nan-Dect for wells 4,5,and 6 on <br /> both 1216 and 121'2$!90. Wells 2 and 7 showed prestmcc of Benzene contamination, as <br /> follows: <br /> MW-2 1216 &nzene =6.7µg/l <br /> Ethyl Benzene=5.5 14g11 <br /> 12/28 Benzene=2.7µg/1 <br /> Toluene=2.3 ggll <br /> ELiyl Benzene=l.1 µ911 <br /> Total Xylene=!l.t�µgll <br /> I� <br /> t , <br />