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1 <br /> <br /> Mr. James C. Stevens <br /> July 14, 1997 <br /> Page 2 <br />' During drilling of borehole MWS, soils were monitored for the presence of hydrocarbon vapors <br />' using a Thermo Environmental Instruments Model 580B organic vapor monitor (OVM) photo- <br />ionization detection meter (PID) calibrated to an isobutylene standard. Soil sampling depths, PID <br />readings, and lithologic descriptions for the borehole is included on the attached lithologic and <br />' well completion log. <br />A site map displaying the location of the monitor wells is included as Figure 2. Groundwater <br />samples were obtained from the three monitor wells (MW1, MW4 and MWS). Monitor wells <br />MW2 and MW3 were dry. The groundwater samples were submitted for laboratory analysis. The <br />samples were analyzed for volati]e organics using EPA Method 624, semi-volatile organics using <br />' EPA Method 625, pesticides using EPA Method 608 and herbicides using EPA Method 8150. <br />The samples were also analyzed for Human Health Standards and Secondary Drinking Water <br />Standards listed in the Colorado Department of Health, Water Quality Control Commission, Thg <br />Basic Standards for Ground Water. In addition, all monitoring wells were measured for depth to <br />water to determine the groundwater gradient and flow direction. <br />Prior to sampling, each well was purged of a minimum of three well volumes of water or until the <br />well was dry and allowed to recharge. On-site measurements of electric conductivity, pH, and <br />' temperature were recorded to ensure that the well stabilized so that a representative sample of the <br />aquifer was collected. Copies of the field activity forms are attached. The bailer used to develop <br />the wells was decontaminated with aphosphate-free detergent and distilled water between each <br />well. Samples were collected with a Teflon disposable bailer and placed on iced until delivery to <br />the laboratory for analyses. The samples analyzed for phenols, odor, radiochemistry, cyanide, <br />foaming agents, metals, nitrates, nitrites, fluoride, alkalinity, chloride, color, total dissolved solids <br />(TDS), sulfides, and pH were filtered in the field (.45 microns). Chain-of-custody forms <br />accompanied the samples throughout the shipment and are included with the attached analytical <br />report. <br />~ Laboratory results indicate that samples obtained from wells MWI, MW4, and MWS were below <br />' detection limits for pesticides, PCBs, herbicides, semi-volatile organics, and volatile organics. <br />total dissolved solids (TDS) were within the acceptable range for groundwater. The remaining <br />analytes, identified in the Hutnan Health Standards and Secondary Drinking Water Standards <br />' tables with The Basic Standards for Ground water either were below the method detection limits <br />or below the respective standards with the exception of barium fluoride and manganese. Barium <br />and fluoride concentrations were slightly above the Human Health Standards in wells MW1, <br />' MW4, and MWS. MW1 is located upgradient from the landfill. Therefore, the barium and <br />fluoride concentrations may be naturally occurring as a result of local lithologies. Manganese <br />concentrations of 0.052 mglL were repotted in well MWS. This concentration was slightly above <br />the secondary drinking water standard of 0.050 mg/L. Analytical results for the Human Health <br />