Energy and Environment Monitor US EPA’s Underground Injection Control Program (UIC) classifies injection wells into five categories. New regulations, proposed in July 2008, under the Safe Drinking Water Act would establish a sixth class to regulate the geologic sequestration of carbon dioxide. For more information on the proposed regulations and pilot programs, see previous Energy and Environmental Monitor Climate Change articles by Chris Hunter.
The five current categories of injection wells are as follows:
1. Deep disposal of hazardous wastes, industrial non-hazardous liquids or municipal wastewater.
2. Deep disposal of hydrocarbons and oil and gas production fluids for storage.
3. Deep disposal of fluids associated with solution mining of minerals
4. Utilized by specific ground water remediation projects under state or federal programs
5. Typically, but not always shallow disposal of non-hazardous fluids (currently utilized for geologic sequestration pilot projects)
As evident from the different categories of injection wells, they are a valuable tool in many industries. Injection wells are a good solution when the local geologic setting is a match with the necessary disposal application. For example, the ideal situation, i.e. rock permeability and depth, for a natural gas brine disposal well could be different than a carbon dioxide injection.
The Pennsylvania Department of Environmental Protection (PADEP) is revisiting the importance of injection wells not only because of interest in geologic sequestration but because of recent elevated levels of Total Dissolved Solids (TDS) in tributaries of major watersheds. A rise in TDS can be attributed to many sources, but has led the PADEP to renew their commitment to research avenues other than local wastewater facilities for disposal of natural gas drilling and fracing fluids. For this reason, a resurgence in mapping for possible injection well sites has begun in Pennsylvania. This should not be necessary in areas such as West Virgnia where utilization of injection wells are common practice.
This topic is something that should not be dismissed easily for both business and environmental reasons. The use of injections wells, when used correctly, could serve as another tool for states like West Virginia and Kentucky to benefit from their unique geology.
For a good depiction of injection wells and how the categories differ in purpose and structure, please see http://www.epa.gov/safewater/uic/wells_drawings.html .
This article was authored by Rachel Shanteau, Acacia Environmental Group LLC. For more information on the author see here.
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