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Snow Environmental Solutions
Phytoremediation – Use of Trees for Groundwater Cleanup at a Former Refinery
Groundwater at a former petroleum refinery in Oklahoma is contaminated with petroleum hydrocarbons, including benzene and light non-aqueous phase liquids (LNAPL) in the form of mobile and residual phases, over a widespread area in excess of 350 acres. Previous multi-phase pump-and-treat efforts in the high permeability sandy confined aquifer were expensive and ultimately deemed infeasible due to iron plugging of equipment and piping. A 3-year long pilot study assessed the feasibility of using phytoremediation to achieve hydraulic control of groundwater contaminant migration as required by an agreement with the state environmental agency. The selectedTreeWell®system for the site uses 42-inch diameter plastic-lined boreholes completed into the aquifer, backfilled with an organic soil mixture for tree rooting, and planted with a variety of tree species native to and adaptable to the area. This approach is designed to exclude surface water sources to the trees and force them to utilize groundwater only. During two phases of full-scale implementation in 2015 and 2016, 404 trees were planted for groundwater extraction and in situ biotreatment that, in combination with natural attenuation and oxygen injection, is designed to achieve the project goal of plume containment.
Brad Snow is a self-employed environmental consultant based in Austin Texas (President-for-Life and Benign Dictator operating Snow Environmental Solutions from a spare bedroom). His 34 year professional practice has focused on strategic management of environmental liabilities, risk-based site remediation, environmental due diligence, and litigation support. Brad has conducted soil and groundwater investigations and cleanup projects throughout the U.S. and internationally for a wide variety of industrial clients.