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Herkelrath, William N

The U.S. Geological Survey (USGS) investigated the natural attenuation of subsurface petroleum hydrocarbons leaked over an unknown number of years from an oil pipeline under the Enbridge Energy Limited Partnership South Cass Lake Pumping Station, in Cass Lake, Minnesota. Three weeks of field work conducted between May 2007 and July 2008 delineated a dissolved plume of aromatic hydrocarbons and characterized the biodegradation processes of the petroleum. Field activities included installing monitoring wells, collecting sediment cores, sampling water from wells, and measuring water-table elevations. Geochemical measurements included concentrations of constituents in both spilled and pipeline oil, dissolved alkylbenzenes...
Categories: Publication; Types: Citation
The U.S. Geological Survey (USGS) investigated the natural attenuation of subsurface petroleum hydrocarbons leaked over an unknown number of years from an oil pipeline under the Enbridge Energy Limited Partnership South Cass Lake Pumping Station, in Cass Lake, Minnesota. Three weeks of field work conducted between May 2007 and July 2008 delineated a dissolved plume of aromatic hydrocarbons and characterized the biodegradation processes of the petroleum. Field activities included installing monitoring wells, collecting sediment cores, sampling water from wells, and measuring water-table elevations. Geochemical measurements included concentrations of constituents in both spilled and pipeline oil, dissolved alkylbenzenes...
Categories: Publication; Types: Citation
Our results show that subsurface crude-oil degradation rates at a long-term research site were strongly influenced by small-scale variations in hydrologic conditions. The site is a shallow glacial outwash aquifer located near Bemidji in northern Minnesota that became contaminated when oil spilled from a broken pipeline in August 1979. In the study area, separate-phase oil forms a subsurface oil body extending from land surface to about 1 m (3.3 ft) below the 6–8-m (20–26 ft)-deep water table. Oil saturation in the sediments ranges from 10–20% in the vadose zone to 30–70% near the water table. At depths below 2 m (6.6 ft), degradation of the separate-phase crude oil occurs under methanogenic conditions. The sequence...
Categories: Publication; Types: Citation
Numerous models are in widespread use for the estimation of soil water retention from more easily measured textural data. Improved models are needed for better prediction and wider applicability. We developed a basic framework from which new and existing models can be derived to facilitate improvements. Starting from the assumption that every particle has a characteristic dimension R associated uniquely with a matric pressure ψ and that the form of the ψ–R relation is the defining characteristic of each model, this framework leads to particular models by specification of geometric relationships between pores and particles. Typical assumptions are that particles are spheres, pores are cylinders with volume equal...
Categories: Publication; Types: Citation
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