Pump and Treat Technology

Description

When contaminated groundwater is removed from the subsurface by pumping, it is often treated before it is discharged. Hence this method is referred to as pump-and-treat. This is the most common form of groundwater remediation. It is often associated with treatment technologies such as Air Stripping and Liquid-phase Granular Activated Charcoal. Treatment systems are described separately.

The well design, pumping system, and treatment are dependent on the site characteristics and contaminant type. It is not uncommon to find many wells extracting groundwater at the same time. These wells may be screened at different levels to maximize effectiveness. A major component of any groundwater extraction system is a ground water monitoring program to verify its effectiveness. Monitoring the cleanup allows the operator to make adjustments to the system in response to changes in subsurface conditions.

A major component of a pump-and-treat system is determining when to turn the system off. For contaminants regulated by the EPA, levels established under the Safe Drinking Water Act are usually the prevailing levels that groundwater has to meet. Termination requirements are based on the cleanup objectives defined in the initial stage of the remedial process, combined with site-specific aspects revealed during remedial operations.

Limitations and Concerns

Pump-and-treat systems often take a very long time (e.g., 50 -100 years) to meet cleanup goals.

Pumping depresses the groundwater level, leaving residuals sorbed to the soil. After the groundwater level returns to its normal level, contaminants sorbed onto soil become dissolved. This phenomenon is called "rebound". Rebound tests should be performed frequently in the first few years after the system is turned off, and after major precipitation or flooding events.

Applicability

Pump-and-treat systems remove groundwater contaminated with a variety of dissolved materials, including VOCs, SVOCs, fuels, UXO (i.e., explosive compounds) and dissolved metals.

Technology Development Status

Pump-and-treat is a mature technology.

Web Links

http://www.lgst.com/matrix/section4/4_58.html

http://www.sgcleanup.com/works/remtech.html

Other resources

None have been identified.