Paper No. 6
Presentation Time: 8:00 AM-12:00 PM
HYDROGEOLOGIC INVESTIGATION OF A QUATERNARY VALLEY FILL, ERIE COUNTY, NORTHWESTERN, PA
Just north of Albion, PAA, two private, domestic wells intercepted an artesian aquifer that lies beneath a groundwater well-field owned by the town of Albion. Desiring to develop this aquifer, town officials chose a site to drill on a line crossing their property between the two private wells. They drilled over 300 ft. and missed the aquifer. The purpose of this study, then, was to locate this aquifer for the town of Albion. This is an interesting case study of the interaction between pro-glacial topography and ice-marginal deposition upon aquifer development. Bedrock geologic mapping, depth to bedrock surveying, and well drilling logs reveal a deeply buried (nearly 300 ft.), glacially scoured bedrock trough with step-like drops, terminating with a slight bottleneck. Dog-leg bends down the axis of the trough correspond to regional NW-SE, NE-SW bedrock structural trends. The aquifer of interest is found nearly 200 ft. below the surface and overlies nearly 100 ft. of undifferentiated sediments. An upper, near surface unconfined aquifer was also found. Both aquifers are likely related to depositional environments associated with the late Wisconsin Ashtabula Ice front. The Ashtabula Ice front stagnated just to the north of the study area. Meltwater flow through the study area was deflected by bedrock highs and exposed valley sidewalls, depositing a sinuous accumulation of gravels and sands. Meltwaters later impounded, forming a pro-glacial lake within the study area. Lake-bed silt deposition capped the underlying outwash gravels and sands resulting in the development of the confined nature of the artesian aquifer of interest. Later ice-marginal, kame-deltaic deposition yielded the gravels and sands associated with the upper aquifer. Finally, spatial reconstruction of the braided outwash environment of the artesian aquifer led to a successful drilling site.