Bohling, Geoffrey C. / A ground penetrating radar study of water table elevation in a portion of Wisconsin's central sand plain
I. Introduction: motivation and objectives, pp. 1-9 PDF (2.5 MB)
9 GPR surveys were performed. Of the 27 observation wells shown, 21 are next to roads where surveys were performed and are therefore potential calibration and verification points for the radar study. It is important to point out that most of the " observation wells" shown in Figure 2 are actually the shallowest piezometers in nests of 3 to 5 piezometers screened at different depths in one place. Sixteen of the 27 shallow piezometers shown are in fact observation wells, meaning that the water table inter- sects the screened interval and thus that the water level actually represents water table elevation. Of the 21 shallow piezometers next to surveyed roads, 12 are actually observation wells. In the remaining nine, water stands between 0.5 and 12 feet above the top of the well screen. It is possible that, due to vertical hydraulic gradients, the water level in piezometers screened below the water table would stand higher or lower than the actual water table elevation. In an actual water table reconnais- sance study using GPR, one in which only a few observation wells or piezometers exist in the area, very little or no information concerning vert- ical gradients would be available. These 27 shallow piezometers will be referred to as observation wells in this study. Also, the borings for grain size analyses (locations shown in Figure 2) are given the labels of the piezometers which were installed in the auger holes from which the borings were taken.