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mining operation! A copy ofthe CDPS Industrial General Permit issued to AI with an effective date of October 1, 2002 is enclosed as Attachmem 3. This permit has two outfalls and does not require any water quality monitoring even though numeric standards exist for the Upper South Platte River Subbasin in this area. More important was the fact that the Water Quality Control Division did not review the permit application for antidegradation criteria. The mining site and my property are within the historical ground water contaminant plume emanating from the Rocky Mountain Arsenal (RMA) located 2.5 miles to the southeast. Weapons production and industrial manufacture of pesticides and herbicides contaminated soil, sediments, and water at the RMA. From 1942 through 1969, the Army manufactured weapons including nerve agents at the arsenal. Shell Chemical Company leased part ofthe site from the Army and produced pesticides and herbicides from 1951 until 1982. Offpost ground water contamination was not identified until 1974. EPA added the arsenal to its National Priorities List (Superfund) in 1987. According to the Tri-County Health Department, the majority of offpost contamination is found in the shallow, unconfined aquifer (alluvial aquifer). In their overview ofthe R.Mt~ enclosed as Attachment 4, Tri-County Health Department states, "The main Arsenal-related contaminants in the groundwater aze: volatile organic chemicals, such as Benezene, Chloroform, Toluene, and Trichloroethylene (TCE); pesticides and other related chemicals, such as Aldrin, Atrazine, Chlordane, Dibromochloropropane (DBCP), Dieldrin, Enfrin, and Isodrin; Army nerve agent by- products like Diisopropylmethylphosphonate (DIlvIP); and heavy metals, including Arsenic, Cadmium, Chromium, Lead, and Mercury. Table SA, also included in Attachme~ 4, from the Public Health Assessment dated September 30, 1996 prepared by the Agency for Toxic Substances and Disease Registry lists the maximum historical detection levels and range of detections for a number of these contaminants. For discussion purposes, I will focus on Diisopropyl Methylphosphonate (DIMP) as it was the subject of numerous investigations in this area. D1MP does not occur naturally and is created as a by-product ofthe production ofthe chemical agent Sarin. Concerns regarding the toxicity to this chemical prompted the Water Quality Control Commission to establish a statewide DIMP standard of 8µg2 for both surface water and ground water in Colorado. In 1990, the Colorado Department of Health tested my drinking water well (Arapahoe aquifer) and found 27.9 µg2 D]MP. Additional sampling by Tri-County Health in 1991 produced no detectable levels. 1985 sampling of my alluvial irrigation well by Tri-County Health produced a DIMP concentration of 5.2 µg/L. As a result of these investigations, the residence was provided with bottled water and continues to utilize that source for drinking water. During the Pre-Hearing conference, I leazned that AI has also tested for D1MP in this azea and has reported concentrations above the detection limits. My concern is not the contaminant concentrations in ground water today, rather the release of adsorbed contaminants due to excavation mining operations. DIMP is a member of a class of semi- volatileorganic compounds, though somewhat soluble, that tend to adsorb on soil particles. Documerrtation of this characteristic is enclosed as Attachment 5. Adsorption is the most connmon way in which contaminants are removed from the ground water as it moves through a porous medium (Tchobanoglous, 1987). Adsorption occurs when a dissolved ion or molecule becomes attached to the surface solid particles, sedimentary grains. The amount of a contaminant subject to adsorption in a ground water aquifer is dependent upon that chemical's distribution coefficient. The forces that hold the molecule to the sedimentary grains aze very weak. These adsorbed contaminants are not only within the current aquifer matrix but also the zone of historical water table fluctuation as