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Mr.John Lane June 2,2006 <br /> Ground Zero Analysis,Inc <br /> system. Primarily because the permanganate persists so long in the subsurface that it is <br /> consumed slowly by the natural organics. <br /> Comment C: Address concerns whether adverse effects will occur to water quality (for <br /> ISCO— oxidation of metals and general minerals to harmful species, clogging of aquifer <br /> pore space, etc.) <br /> The bench study will address the issues of chromium, metals and bromide. Your list of <br /> analytes in the work plan covers the potential ISCO related compounds. The ISOTEC <br /> process produces both oxidants and reductants and delivers ferrous iron, a reductant <br /> itself, this helps prevent the production of oxidized metal species. We have actually <br /> observed temporary decreases in Cr+6 following injection. Again, the oxidation state of <br /> the saturated zone is short lived with this process, therefore oxidation of metals does not <br /> continue for months at a time as with a permanganate project. <br /> The turbidity, TDS, dissolved oxygen, pH, and temperature will change as a result of the <br /> injection process. Turbidity, TDS, dissolved oxygen (DO) and temperature will increase <br /> temporarily. The pH may temporarily drop to the 5-6 range. Temperature will. not <br /> increase more than 15-25°F. Any groundwater sampling for metals should include a field <br /> filtering step prior to acidification due to the turbidity increase. <br /> We have not experienced injection handicaps due to aquifer clogging at any previous <br /> project. We have injected thousands of gallons of reagent through injection well screens <br /> multiple times without a noticeable increase in injection pressure. We inject a small <br /> percentage of the pore volume with each injection event. At this site we will be using <br /> direct push injection; therefore no single injection location will be used more than once. <br /> Locations are moved laterally from the first injection event locations during each <br /> subsequent injection event. ISCO aquifer plugging is primarily associated with <br /> manganese dioxide production during permanganate injections utilizing large injection <br /> volumes at single injection locations. <br /> Comment D: and if so, what are the projected extent of the adverse effects and the time <br /> required to restore the aquifer to background levels. <br /> The ISOTEC process disrupts equilibrium or steady state conditions within the aquifer <br /> with regard to dissolved contaminant concentrations, turbidity, TDS, DO, temperature <br /> and pH. Depending on site specific conditions (groundwater flow rate, re-adsorption <br /> rates, dilution, dispersion, and biologic degradation) we have seen the return to <br /> equilibrium conditions take weeks to several quarters. Turbidity, TDS, DO, temperature <br /> and pH return quicker than dissolved contaminant concentrations. <br /> Comment 1: The work plan has a statement that a Colorado-certified laboratory will be <br /> used. Please submit a copy of the currently valid Colorado ELAP certified or NELAP <br /> accredited document (per CCR 23, Section 100825-100920), or a copy of the current CA- <br /> DHS certification. <br /> ISOTEC's New Jersey office will conduct the bench study and use a New Jersey <br /> accredited laboratory for the analytical. The accreditation certificate is attached. <br /> 6452 FIG STREET,SUITE C,ARVADA,COLORADO 80004 <br /> PHONE: 303-843-9079 FAx: 303-843-9094 <br />