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Track: Environmental Management
Roger Koelpin
IDEM OSHWM HW Geology
100 North Senate
PO Box 6015
Indianapolis, IN 42602-6015
Telephone: 317-232-8726
Fax: 317-232-3403
E-mail: ruk@opn.dem.state.in.us
Brian Murray, Kevin Miller
Comparison of Three Vintages of Groundwater Monitoring Well Locations in the Indiana Department of Environmental Management Hazardous Waste Geology Section's GIS
Defining Issue: NAD83 UTM coordinates for over 1,700 wells in northwest Indiana have been obtained through three separate surveying efforts. ArcView was used to differentiate and facilitate the comparison of the three different vintages of locations. Methodology: Three separate surveys have been done for groundwater monitoring wells in northwestern Indiana. The United States Geological Survey located seventy-nine wells in their regional network with conventional surveying methods, using second and third order survey control. The U.S. EPA located 268 wells in another regional effort, using handheld GPS receivers adjusted with either code or phase corrections. The Indiana Department of Environmental Management, Hazardous Waste Geology Section obtained GPS coordinates that were used to rectify digital facility maps from which locations for 1,500 wells were digitized. The IDEM GPS efforts used first and second order monuments with survey grade static methods. ArcView was used to identify which wells
were common to two or more vintages. Of the over 1,700 wells, ninety wells had both EPA & IDEM locations, sixty-one wells had both EPA & USGS locations, seven wells had IDEM & USGS locations; and five wells had locations from all three efforts. The EPA set was used as a standard for comparisons because of the number of wells common to either the IDEM or USGS data sets. The locations were compared between EPA and IDEM and EPA and USGS efforts, resulting in two sets. Distances between locations in respective sets were calculated and then compared statistically. Distances greater than one kilometer were attributed to typographical errors and dropped from each set. The average distance between EPA and IDEM locations was 131 m and 231 m for the EPA and USGS efforts. The average difference in distances calculated for both sets is statistically significant at the 95 percent level. A confirmation survey by IDEM is being considered for spring 1997.
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