MODELING SUBSURFACE GLACIAL DEPOSITS IN 3-DIMENSIONS AT THE POLELINE ROAD DISPOSAL AREA, FORT RICHARDSON, ALASKA

Interpretation of the subsurface distribution of glacial deposits is especially complicated in areas where ample outcroppings are not available. This investigation sought to better understand the geology of the Poleline Road Disposal Area, Fort Richardson AK, using a combination of geophysical techniques, limited borehole geologic data, hydrological data and three dimensional modeling techniques.

The Poleline Road site, located about two km south of Eagle River, AK is situated in a topographic low surrounded by a wooded hill to the west, a large wetland to the south and southwest, and low wooded hills to the north and east. The regional geology of the Fort Richardson area is characterized by several glacial, glacial-marine and glacial-alluvial depositional events of Quaternary age that deposited a complex system of interfingering deposits on the bedrock. These deposits are further complicated locally by a series of outburst floods that eroded some deposits completely while reworking others.

Various geophysical techniques, including ground penetrating radar, DC resistivity, and seismics were used to map the vertical and lateral extent of these deposits. Ground truth data are obtained from limited available deeply penetrating borehole geological logs in conjunction with hydrological data. A conceptual model of local glacial deposits was developed and used as the basis for modeling these data three dimensionally.