Identification Of A Multiaquifer Ground-Water Crosscontamination Problem In The Stockton Forjmation By Use Of Borehole Geophysical Methods, Hatboro, Pennsylvania

Abandoned industrial and public supply wells and improperly constructed monitoring wells open to<br>multiple water-bearing zones in the Triassic Stockton Formation in Pennsylvania short circuit the<br>ground-water-flow system and are conduits for contaminant transport. Borehole geophysical methods<br>were used to construct a three-dimensional lithostratigraphic model, identify fluid-producing and<br>fluid-receiving zones (fractures), measure vertical borehole-fluid movement, and serve as the basis for<br>proper design and construction of monitoring wells. Natural-gamma, single-point-resistance, caliper,<br>fluid-temperature, and fluid-resistivity logs were run in 16 boreholes 149 to 470 feet deep.<br>The lithostratigraphic model of the dipping sedimentary rocks of the Stockton Formation primarily is<br>based on natural-gamma, single-point-resistance, and caliper logs. Geophysical logs from one borehole<br>were compared to a 200-foot-long rock core from that borehole to determine the relative response<br>of the geophysical logs to lithology. This comparison was used as the basis for litbologic interpretation<br>of the geophysical logs of the other boreholes. The interpreted lithostratigraphy correlates well from<br>borehole to borehole.