UST Corrective Action Technologies: Engineering Design of Free Product RecoverySystems

摘要

The objective of this project was to develop a technical assistance document forassessment 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. 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. The applicability of trenches and vacuum-enhanced product recovery to hydrocarbon spills is also discussed.