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UST CORRECTIVE ACTION TECHNOLOGIES: ENGINEERING DESIGN OF FREE PRODUCT RECOVERY SYSTEMS
Citation:
Parker, J. C., D. W. Waddill, AND J. A. Johnson. UST CORRECTIVE ACTION TECHNOLOGIES: ENGINEERING DESIGN OF FREE PRODUCT RECOVERY SYSTEMS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-96/031 (NTIS PB96-153556), 1996.
Description:
The objective of this project was to develop a technical assistance document for assessment of subsurface hydrocarbon spills and for evaluating effects of well placement and pumping rates on separate phase plume control and on free product recovery. Procedures developed for estimation of hydrocarbon spill volume include interpolation and spatial integration of measurements from soil cores, and fluid level data from monitoring wells. The first method involves vertical integration of soil concentration measurements to yield oil volume or species mass per unit area followed by kriging and areal integration to estimate the total mass or volume within the measurement zone. This method is especially well suited to determine the amount of residual product in the unsaturated zone. The second method involves kriging of well fluid levels, calculation of free oil volume per area using a physically based model for vertically hydrostatic three phase fluid distributions that converts well product thickness to soil product thickness, followed by areal integration to estimate the volume of free product floating on the water table. A procedure is presented to evaluate effects of steady-state water pumping from multiple point sources on the oil flow gradients to evaluate if hydraulic control of plume spreading will be obtained for a selected system of pumping wells and/or trenches. Estimates of residual oil in the unsaturated and saturated zones are made from three phase capillary pressure-saturation relations and from the initial oil thickness distributions and computed water table drawdown, which enable determination of the recoverable spill volume for alternative well configurations. A variety of practical examples and case studies are presented to illustrate the methodology and to demonstrate how various factors interact to affect free product recovery system effectiveness. The applicability of trenches and vacuum enhanced product recovery to hydrocarbon spills is also discussed. This report was submitted in fulfillment of Contract No. 68-C2-0108 by International Technology Corporation and its subcontracted Environmental Systems & Technologies, Inc., under the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from June 1993 to April 1995, and work was completed as of April 30, 1995.