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Dissolved zinc concentrations in samples from this point ranged from 200 ug/L to 490 <br /> ug/L. <br /> Dissolved cadmium was not detected in samples collected by ABC from approximately <br /> the same location as RT-SW-03(Tiger-5). Dissolved manganese concentrations ranged <br /> from non-detectable to 6 ug/L. Dissolved zinc concentrations at this point were <br /> consistently measured at 20 ug/L. These values are all within the table-value standards <br /> for the Swan River adjacent to and downstream of the IXURoyal Tiger site,and tend to <br /> confirm the conclusion reached by CDPHE(2002)that applicable water-quality <br /> standards are met in the Swan River reaches adjacent to and downstream of the <br /> IXURoyal Tiger site. <br /> I <br /> 7.3.2 Sediments <br /> CDPHE (2002)reports that sediment samples collected from the ditch along the south <br /> side of the Swan River valley exhibit elevated concentrations of cadmium, copper,lead, <br /> mercury, silver, and zinc for a distance of about 2,200 feet below the point where the adit <br /> discharge reaches the ditch. The effects of site conditions on sediment concentrations <br /> appears limited to this portion of the ditch;there is no evidence of sediment impacts in <br /> the main Swan River channel. <br /> 7.4 Soils <br /> CDPHE collected three soil samples from on-site areas which,at the time of sampling, <br /> were occupied for residential use. Two of the samples were collected from potentially <br /> impacted areas,while the third sample was collected from an area judged by CDPHE to <br /> be representative of background conditions. Analytical results for soil samples are <br /> summarized in Table 11. <br /> CDPHE (2002)indicates that maximum concentrations of arsenic,cadmium,copper, <br /> lead, mercury,silver,and zinc were elevated above background levels. Concentrations <br /> were compared to USEPA Region III risk-based concentrations, Region IX Preliminary <br /> Remediation Goals, and the Superfund Chemical Data Matrix reference values for a <br /> residential exposure scenario. Using this comparison,concentrations of lead and <br /> arsenic were found to exceed the relevant screening values. <br /> In the time since the CDPHE (2002)report was completed,the three individuals <br /> occupying the site have relocated. There is no longer any residential occupancy of the <br /> IXLRoyal Tiger site. Anticipated future land use does not include any residential use of <br /> the property. The residential-use scenario presented in CDPHE(2002),while useful at <br /> the time the report was prepared, is not relevant to current or future land use at the <br /> IXURoyal Tiger site. <br /> 7.5 Surface-Water and Sediment Pathways <br /> Source material, surface-water, and sediment samples collected from appropriate on- <br /> site and off-site locations indicate a release from the piles and the adit associated with <br /> the IXURoyal Tiger site to the Swan River valley in the area of the site(CDPHE, 2002). j <br /> CDPHE(2002)also concludes that site data indicate that the buried mill tailings may be <br /> inundated by adit discharges,resulting in further leaching of site-related constituents into <br /> isolated water bodies in the ditch along the south side of the Swan River valley. <br /> Receptors in the drainage include riparian wetland vegetation present along the ditch on <br /> the south side of the Swan River valley. CDPHE (2002)indicates that the effects of the <br /> IXURoyal Tiger VCUP Application --._�. ..�...._. Page 19 of 33 i <br />