EPA Grant Number: R827015-01-0
Title: Demonstration of a Subsurface Drainage System for the Remediation of Brine-Impacted Soil
Investigators: Thomas M. Harris, John Veenstra
Institutions: University of Tulsa, Oklahoma State University
EPA Project Officer: Bala Krishnan
Project Period: February 1, 2000 to December 21, 2000 (N/C Ext. to April 22, 2001)
Project Amount: $99,769
Research Category: Brine spill remediation
Brine-impacted soil is the most common environmental problem associated with the onshore production of oil and gas. Salt causes the outright death of plants, and the consequent erosion of topsoil. The remediation of brine-impacted soil may be motivated by lease agreements, federal and state regulations, landowner claims, and the fear of long-term liability. At the present time, the most common remediation strategy applied to brine-impacted soil is in-situ chemical amendment (ISCA),. This treatment entails the application of gypsum, hay, etc. to the soil to restore its permeability and fertility. Since such treatments are designed to encourage the downward movement of salt through the soil profile, they will fail if there is an impediment (such as a low-permeability subsoil) to this downward movement. Such conditions are not uncommon in the oil-producing counties of northeastern Oklahoma, for example.
Subsurface drainage may be used to accelerate the remediation of brine-impacted soil by enhancing the lateral movement of salt through the contaminated topsoil. This project, which concerns the further development of this technology, has three objectives. The first is to evaluate innovative uses of limestone gravel in the drainage for the purpose of reducing the cost of installing the drainage. This material may also serve to enhance the permeability of the surrounding soil, by providing the calcium ions required to counteract the sodicity of the brine-impacted soil. In addition to the treatment of a contemporary brine spill, this strategy will be considered for the treatment a historical "brine scar", where topsoil applied to the site must be protected from the upward migration of salt during periods of dryness. The third objective is to demonstrate the use of a solar evaporation pond for collecting the salty leachate from a subsurface drainage system, and reducing its volume through evaporation in order to reduce the cost of disposal.
The Keefer lease, 1 mile east of Bartlesville, Oklahoma on Highway 60, has been chosen as the site for this demonstration. This lease was the site of a large waterflooding operation in the 1960's. It is currently operated by Marjo Oil Co. One area within this site (Area I) is contaminated with salt but has retained much of its topsoil. Another more extensive area (Area II) is deeply scarred by erosion, with absolutely no topsoil remaining.
An environmental consultant hired to evaluate the project recommended complete containment of the leachate from both areas. The evaporation pond has been resized to accommodate leachate from Area II only. The operator of the lease has agreed to allow leachate from Area I to be pumped into the produced water injection well adjacent to this area. The Area I system will thus be equipped with a sump from which the leachate can be pumped to the feed tank for this well. Bids for the construction of the remediation system are currently being solicited.