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25. <br /> <br />26. <br /> <br />27. <br /> <br />28. <br /> <br />29. <br /> <br />Ether compounds such as ethyl ether and tetrahydrofuran are normally <br />associated with industrial solvents, particularly solvents for PVC products. <br />Tetrahydrofuran can also be found in Iow levels in food packaging. Ether <br />compounds are lighter than water compounds and are highly volatile and <br />extremely soluble in water (Remedial Investigation). <br /> <br />Hatogenated VOCs include chlorinated alkanes and alkenes and fluoroatkanes. <br />Chlorinated compounds are generally associated with industrial and household <br />solvents. Fluoroalkanes, more commonly known as freon, are associated with <br />aerosol spray cans, polyurethane foam and refrigerants. Halogenated <br />compounds are more dense than water, with the exception of chloroethane and <br />vinyl chloride, and are highly to extremely volatile. These compounds range in <br />aqueous solubilities from slight to highly soluble (Remedial Investigation). <br /> <br />Trace heavy metals have only been detected sporadically at downgradient well <br />locations nearest to the landfill. Concentrations have not been significantly <br />greater than those detected at ambient locations. Metals detected, with the <br />exception of zinc, have had concentrations less than 10 ug/I and in most cases, <br />concentrations have been nearer to the detection limit of 1 ug/t. Zinc ranged <br />in concentrations up to about 40 ug/I at impacted downgradient wells. <br />However, upgradient concentrations for zinc were significantly higher than <br />those zinc concentrations detecteddowngradient. Metals do not appear to be <br />migrating from the landfill in the groundwater because of the neutral or slightly <br />basic pH conditions of the aquifer. The high bicarbonate content (alkalinity) of <br />the neutral groundwater buffers the acidic leachate generated at the landfill to <br />keep the pH of the groundwater near neutral, thereby immob:,iizing metals. <br /> <br />Limited inorganic water quality data are available for private wells. From the <br />available water quality data, it appears that the private wells sampled, whether <br />bedrock, lower sand, or unknown screened position, are free of any impact <br />from landfill ope'rations (Remedial Investigation). <br /> <br />Currently, no public health hazard exists and that limited potential exists for the <br />occurrence of future hazards to public health. The results of the investigation <br />have also indicated that site conditions are such that, through the application <br />of available technology, water quality impacts in the vicinity of the Anoka <br />Regional Sanitary Landfill can be effectively managed (Remedial investigation). <br /> <br />5 <br /> <br /> <br />