REPORT (PDF)

This paper was presented at the Environmental Systems Research Institute (ESRI) 2007 International User Conference and published in the conference proceedings.

Over the past decade the public has become more and more concerned with water resources. As a proactive measure, the Barrington Area Council of Governments (BACOG), an association of villages and townships in far northwest suburban Chicago, is currently working on a project to establish water resource baseline conditions in their immediate and surrounding area. Under the direction of BACOG and a professional advisor, a committee of volunteers is conducting much of the work of this water resource initiative using data readily available for little or no cost.

To establish water resource baseline conditions using limited resources, BACOG developed a method to produce baseline hydrogeologic unit maps from readily available borehole log data using GIS querying techniques. Borehole strata descriptions were converted to numerical values by establishing the average hydraulic conductivity of the combined soils making up the stratum of interest. These hydraulic conductivity values were then used to assign each stratum to a hydrogeologic unit based on typical ranges of hydraulic conductivity for aquifers, aquitards and aquicludes. In this manner, the well log data were queried to describe the shallow aquifer system. This approach was used to estimate the health of the shallow aquifer system to plan for sustainability using a water budget model. Estimates were made for the components of the water budget that included: storage, septic loading, inflows including through flow and seepage, discharge, consumption, and outflows including through flow and seepage.

All available stratigraphic data are used to define a given shallow aquifer system and build a representative stratigraphic model. To accomplish this, well log records must be transferred to an electronic database if they are not already available in that format. Most of a project’s objectives will be met by analysis of the resulting model. Innovative mapping techniques are used. These techniques are based on replacing subjective strata descriptions with equivalent average hydraulic conductivity values and the use of statistics to create the model. The report describes the sequential tasks required using this approach.