High Resolution Seismic Reflection Survey To Map Bedrock And Glacial/Fluvial Layers In Fridley, Minnesota

Shallow seismic reflection in conjunction with uphole velocity profiles and local borehole<br>data allowed delineation of discrete laying within the alluvial materials and glacial drift overlying<br>the St. Peters Sandstone and/or the Prairie du Chien dolomites at an average depth of around 120 ft<br>along the western perimeter of the Naval Industrial Reserve Ordnance Plant (NIROP) in Fridley,<br>Minnesota. The primary goals of this study were to determine the feasibility and limitations of the<br>technique and develop a continuous subsurface image of as many geologic/hydrologic contrasts as<br>possible that can be characterized by changes in acoustic impedance. Establishing feasibility includes<br>determining the horizontal and vertical resolution potential, optimum acquisition geometries<br>and parameters, best suited equipment for surface and subsurface conditions, level of effort necessary<br>to delineate the geologic/hydrologic features of interest, and to establish a reasonable set of<br>expectations for the technique at various unique near-surface settings across the entire facility.<br>Shallow seismic reflection profiles allowed delineation of potentially discontinuous confining units<br>within the glacial drift at this site. Incorporation of a high confidence reflection profile with existing<br>hydrologic models should greatly improve the understanding and therefore prediction of contaminant<br>transport and fate models in areas with significant lateral variability. The glacial drift that<br>covers the entire site consists of till, outwash, valley train, and lake deposits.