Remediation: Techniques and Cost - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 391

Water treatment
system

Clean
water

Holding
tank

Ground surface

Groundwater
level

Polluted groundwater

FIGURE 11.15
Groundwater pump and treat system. (From United States Environmental Protection Agency (USEPA), A
Citizen's Guide to Pump and Treat , EPA 542-F-01-0025, Office of Solid Waste and Emergency Response, Washington,
DC, 2001h.)

air sparging, installation of permeable reactive barriers (PRBs), injection of biological
agents, and injection of chemical reagents.
Please do not bury pump and treat systems yet. Pumping and treating groundwater can
be effective at removing significant quantities of contaminant mass under certain favor-
able conditions. One potential application of pump and treat is with young and immature
groundwater plumes. These types of plumes may display only minor amounts of diffu-
sion and their contaminants may not have reached the lower permeable zones (Figure 8.9).
Here, a focused groundwater pump and treat system could be effective (Payne et al. 2008).
With pump and treat technologies, the method used for contaminant removal from
groundwater depends on the type of contaminant. For instance, if the contaminants are
VOCs, the contaminants may be removed by stripping the VOCs from groundwater using
air in a vessel called an air stripper. C ontaminants may also be removed by circulating the
contaminated groundwater through containers filled with activated carbon. The VOCs in
groundwater become attached or sorb to the activated carbon and are removed from the
groundwater (Figure 11.15).
Other common groundwater remediation technologies include (USEPA 2002, 2007):

• In situ soil flushing
• Air sparging
• PRBs
• Injection of biological agents
• Injection of chemical agents
• Monitored natural attenuation
• Institutional controls
• Multiphase extraction