Laserfiche WebLink
• <br />The pH levels for surface and ground water samples ranged 6.99 and 7.54. Because oC the low <br />pH values, carbonates were not detected in any of the surface or ground water samples. Specific <br />conductance, alkalinity, TDS, TSS, and turbidity values were higher in the monitoring well <br />samples than in the surface water samples. Monitoring well DFMW-3 yielded higher specific <br />conductance and TDS values than the other monitoring wells. Monitoring well DFMW-4 <br />contained the highest alkalinity, TSS, and Turbidity values, while monitoring well DFMW-2 <br />contained the lowest specific conductance, alkalinity, TDS, TSS, and turbidity values. Surface <br />water samples collected from DFSW-1 yielded significantly higher specific conductance, <br />alkalinity, TDS, TSS, and Turbidity values than either DFSW-2 and DFSW-3. <br />The reason that baseline parameters tended to be higher at surface water location DFSW-1, is that <br />this station is located in an ephemeral stream. The samples were collected from a marshy bog <br />area, presumably fed by seeps and springs as indicated by the surrounding vegetation of and <br />cottonwoods. Surface water monitoring locations DFSW-2 and DFSW-3 were collected up and <br />downgradient along the St. Vrain River. <br />The high turbidity and TSS indicated from data collected at monitoring well DFMW-4 may be <br />the result of sediments which remained after three casing volumes were bailed Crom this well. <br />• The July 1 I, 1990 "Report on Ground Water Monitor Well Installation Dowe Flats Project" (WTI) <br />stated that organic odors and Hnu readings of IS-30 ppm were observed in monitor well DFMW- <br />1. As noted in Table 1 estimated trace concentrations of acetone, I, 1, 2-Trichlorethane, toluene, <br />ethylbenzene, and total xylenes were reported Cor DFMW-I. Although it is not believed that <br />these compounds are present in the ground water, a resampling of that well, with an expanded <br />list of analytes, is recommended. The resampling will allow a more accurate determination of <br />ground water quality in the well and will identify the cause of the Hnu readings and organics <br />odors observed during drilling. <br />• <br />Redevelopment of DFMW-I is recommended. The well should be purged of three casing volumes <br />every third day for about 10 days. This guarantees representative ground water samples, free <br />of the effects oC well construction. Following this procedure, the ground water should be <br />analyzed for Volatile Organic Compounds, Base Neutral-Acid Extractable compounds, and a <br />modified Total Petroleum Hydrocarbon procedure designed to identify natural or crude <br />petroleum hydrocarbons. <br />P~ojsk Numbs 7~9]-04S <br />]uly R3, 1990 <br />Page 9 <br />