Side-looking underground radar (SLUR): Physical modeling and case history

A modification of conventional surface ground-penetrating radar (GPR) was c onceived, tested, and successfully applied in the field at Brookhaven Natio nal Laboratory (BNL) to investigate waste pits. The modified GPR method con sists of making measurements along a traverse line in a sloping trench with the radar's antenna oriented at an angle of up to 45 degrees from the hori zontal. The direction of propagation of the electromagnetic field for this configuration is not vertical, and the amount of energy scattered from obje cts that are oriented vertically relative to the energy scattered from hori zontal layers is increased. This fundamental feature of side-looking underg round radar (SLUR) measurements is illustrated by physical modeling. Measurements made along parallel trenches that are offset at different dist ances from a vertically oriented object provides GPR cross-sections with a primary plane of investigation that intersects the vertical feature at diff erent depths, SLUR was used at BNL in conjunction with conventional surface GPR measurements (displayed as 3-D blocks and plan-view time slices) to en hance the vertical definition and improve the depth estimates of the waste pits.