Remediation Technologies Screening Matrix, Version 4.0 4.47 Ground Water Pumping/Pump and Treat
(Ex Situ GW Remediation Technology)
  Description Synonyms Applicability Limitations Site Information Points of Contact
Data Needs Performance Cost References Vendor Info. Health & Safety
Table of Contents
Technology>>Ground Water, Surface Water, and Leachate

>>3.12 Ex Situ Physical/Chemical Treatment

      >>4.47 Ground Water Pumping/Pump and Treat
Introduction>> Ground water pumping is a component of many pump-and-treat processes, which are some of the most commonly used ground water remediation technologies at contaminated sites.


Figure 4-47a:
Typical Ground Water Pumping System

Possible objectives of ground water pumping include removal of dissolved contaminants from the subsurface, and containment of contaminated ground water to prevent migration.

The first step of any remediation project consists of defining the remedial action objectives to be accomplished at the site. This involves gathering enough background site information and field data to make assessments of remedial requirements and possible cleanup levels. The first determination is whether cleanup or containment will be the most appropriate remedial action. If cleanup is chosen, the level of cleanup must be determined. If containment is chosen, ground water pumping is used as a hydraulic barrier to prevent off-site migration of contaminant plumes.

The next component consists of the design and implementation of the ground water pumping system based on data evaluated in setting the goals and objectives. The criteria for well design, pumping system, and treatment are dependent on the physical site characteristics and contaminant type. Actual treatment may include the design of a train of processes such as gravity segregation, air strippers, carbon systems tailored to remove specific contaminants.

Another component of any ground water extraction system is a ground water monitoring program to verify its effectiveness. Monitoring the remedial with wells and piezometers allows the operator to make iterative adjustments to the system in response to changes in subsurface conditions caused by the remediation.

The final component is determining the termination requirements. Termination requirements are based on the cleanup objectives defined in the initial stage of the remedial process. The termination criteria are also dependent on the specific site aspects revealed during remedial operations.

Although pumping for containment implies no treatment the following treatments usually follow pumping in pump and treat systems. These are briefly described below and in detail in technology profiles 4.41 through 4.51:

4.41 Bioreators:
Contaminants in extracted ground water are put into contact with microorganisms in attached or suspended growth biological reactors. In suspended systems, such as activated sludge, contaminated ground water is circulated in an aeration basin. In attached systems, such as rotating biological contractors and trickling filters, microorganisms are established on an inert support matrix.

4.42 Constructed wetlands:
The constructed wetlands-based treatment technology uses natural geochemical and biological processes inherent in an artificial wetland ecosystem to accumulate and remove metals and other contaminants from influent waters.

4.43 Adsorption/Absorption:
In liquid adsorption, solutes concentrate at the surface of a sorbent, thereby reducing their concentration in the bulk liquid phase. The most common adsorbent is granulated activated carbon (GAC) (see Technology Profile No. 4.51). Other natural and synthetic adsorbents include: forage sponge, lignin adsorption, sorption clays, and synthetic resins.

4.45 Air Stripping:
Volatile organics are partitioned from ground water by increasing the surface area of the contaminated water exposed to air. Aeration methods include packed towers, diffused aeration, tray aeration, and spray aeration.

4.46 Granulated Activated Carbon (GAC)/Liquid Phase Carbon Adsorption:
Ground water is pumped through a series of canisters or columns containing activated carbon to which dissolved organic contaminants adsorb. Periodic replacement or regeneration of saturated carbon is required.

4.48 Ion Exchange:
Ion exchange removes ions from the aqueous phase by the exchange of cations or anions between the contaminants and the exchange medium. Ion exchange materials may consist of resins made from synthetic organic materials that contain ionic functional groups to which exchangeable ions are attached. They also may be inorganic and natural polymeric materials. After the resin capacity has been exhausted, resins can be regenerated for re-use.

4.49 Precipitation/Coagulation/ Flocculation:
This process transforms dissolved contaminants into an insoluble solid, facilitating the contaminant's subsequent removal from the liquid phase by sedimentation or filtration. The process usually uses pH adjustment, addition of a chemical precipitant, and flocculation.

4.50 Separation:
Separation processes seek to detach contaminants from their medium (i.e., ground water and/or binding material that contain them). Ex situ separation of waste stream can be performed by many processes: (1) distillation, (2) filtration/ultrafiltration/microfiltration, (3) freeze crystallization, (4) membrane pervaporation and (5) reverse osmosis.

4.51 Sprinkler Irrigation:
Wastewater is distributed over the top of the filter bed through which wastewater is trickled. The organic contaminants in wastewater are degraded by the microorganisms attached to the filter medium.

Surfactant Enhanced Recovery

The application of surfactants micelles or steam to the ground water can facilitate the ground water pumping process by increasing the mobility and solubility of the contaminants sorbed to the soil matrix. This material can also facilitate the entrainment of hydrophobic contaminants to allow removal and assures that multi-phase contaminants can be effectively removed. Thus it can increase the contaminant mass removal per pore volume of ground water flushing through the contaminated zone.

The implementation of surfactant-enhanced recovery requires the injection of surfactants into a contaminated aquifer. Typical systems utilize a pump to extract ground water at some distance away from the injection point. The extracted ground water is treated ex situ to separate the injected surfactants from the contaminants and ground water. In order to be cost-effective, the design of the surfactant-enhanced recovery system is critical. Once the surfactants have separated from the ground water they can be re-injected into the subsurface. Contaminants must be separated from the ground water and treated prior to discharge of the extracted ground water.

Drawdown Pumping

Pump drawdown nonaqueous-phase liquid (NAPL) recovery systems are designed to pump NAPL and ground water from recovery wells or trenches. Pumping removes water and lowers the water table near the extraction area to create a cone of depression. The cone of depression in the vicinity of the extraction well produces a gravity head that pushes flow of NAPL toward the well and increases the thickness of the NAPL layer in the well. Each foot of ground water depression provides a driving head equivalent to a pressure difference of 0.45 psi. In most cases, the production of a cone of depression will increase NAPL recovery rates.

Pumping may be accomplished with one or two pumps. In the single-pump configuration, one pump withdraws both water and NAPL. The dual-pump configuration uses one pump located below the water table to remove water and a second located in the NAPL layer to recover NAPL. A single-pump system reduces capital and operating costs and allows simpler control systems and operation, but produces a stream of mixed water and NAPL that must then be separated.

The Dual Phase Extraction (DPE) process for undissolved liquid-phase organics, also known as free product recovery, is used primarily in cases where a fuel hydrocarbon lens more than 20 centimeters (8 inches) thick is floating on the water table. The free product is generally drawn up to the surface by a pumping system. Following recovery, it can be disposed of, re-used directly in an operation not requiring high-purity materials, or purified prior to re-use. Systems may be designed to recover only product, mixed product and water, or separate streams of product and water. Dual phase extraction is a full-scale technology.

Figure 4-47b:
Typical Free Product Recovery Dual Pump System

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Pump and treat.
DSERTS Code: Q1 (Waste Removal - Liquids)

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The first step in determining whether ground water pumping is an appropriate remedial technology is to conduct a site characterization investigation. Site characteristics, such as hydraulic conductivity, will determine the range of remedial options possible. Chemical properties of the site and plume need to be determined to characterize transport of the contaminant and evaluate the feasibility of ground water pumping. To determine if ground water pumping is appropriate for a site, one needs to know the history of the contamination event, the properties of the subsurface, and the biological and chemical contaminant characteristics. Identifying the chemical and physical site characteristics, locating the ground water contaminant plume in three dimensions, and determining aquifer and soil properties are necessary in designing an effective ground water pumping strategy.

Surfactant-enhanced recovery are most applicable for contaminated sites with enhanced dense, nonaqueous-phase liquids (DNAPLs).

Drawdown pumping is effective for NAPL recovery when the aquifer has moderate to high hydraulic conductivity and a thick layer of low-viscosity NAPL. An aquifer with high hydraulic conductivity gives less flow resistance of NAPL into the well. A thick layer of NAPL allows the pumping system to collect a high proportion of NAPL in relation to the amount of ground water. For best operation, the NAPL thickness should be sufficient to completely cover the pump suction port.

Drawdown pumping is a commercially available technology that can be easily implemented with conventional pumps in wells or trenches. System installation costs are low to moderate, but the cost per amount of NAPL recovered varies greatly.

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The following factors may limit the applicability and effectiveness of ground water pumping as part of the remedial process:

  • The potentially long time necessary to achieve the remediation goal

  • System designs fail to contain the contaminant as predicted, allowing the plume to migrate and failure of the pumping equipment.

  • Residual saturation of the contaminant in the soil pores cannot be removed by ground water pumping. Contaminants tend to be sorbed in the soil matrix. Ground water pumping is not applicable to contaminants with high residual saturation, contaminants with high sorption capabilities, and homogeneous aquifers with hydraulic conductivity less than 10-5 cm/sec.

  • The cost of permitting procuring and operating treatment systems is high. Additional cost may also be attributed to the disposal of spend carbon and other treatment residuals and wastes.

  • Biofouling of the extraction wells and associated treatment stream is a common problem which can severely affect system performance. The potential for this problem should be evaluated prior to the installation.

The following factors may limit the applicability and effectiveness of surfactant-enhanced recovery:

  • Subsurface heterogeneities, as with most ground water remediation technologies, present challenges to the successful implementation of surfactant-enhanced recovery

  • Potential toxic effects of residual surfactants in the subsurface

  • Off-site migration of contaminants due to the increase solubility achieved with surfactant injection Obtaining regulatory approval to inject surfactants into an aquifer.

The following factors may limit the applicability and effectiveness of drawdown pumping:

  • Drawdown pumping generally produces large volumes of water in the process of recovering the free product.

  • The production of a cone depression in the water table can smear the free product or trap the fuel in the saturated zone when the water table returns to its original level.

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Data Needs:

Collecting as much background site data as possible, obtaining accurate information on the type of contaminants present, and determining the hydrogeological nature of the site are essential. Contaminant information needed consists of: 1) source characterization, including the volume released, the area infiltrated, and duration of release; 2) concentration distribution of contaminants and naturally occurring chemicals in the ground water and soil; and 3) processes affecting plume development, such as chemical and biological reactions influencing contaminant mobility. Hydrogeologic information include determining the size of the contaminated aquifer, depth to water table, hydraulic conductivity of the surrounding aquifer material, impermeable units and confining layers, ground water flow direction and velocity, recharge and discharge areas, seasonal variations of ground water conditions, and local ground water use. Methods for determining aquifer properties include a slug test, pump test, and a borehole flowmeter test. The pump test consists of pumping one well and measuring the water level response of surrounding wells. A slug test measures the rate at which water level in one well returns to its initial state after inducing a rapid water level change by introducing or with drawing a volume of water. The borehole flowmeter test measures flow direction and rate in a borehole.

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Performance Data:

DOE has developed and tested many pump and treat technologies for hazardous waste removal over the past twenty years. Performance data on some of the most recent DOE sites can be in the Technology Application Analyses and site information below.

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Cost data varies from site to site for ground water pump and treat technology. Recent cost data on a few of DOE's sites can be found below in the links to the Technology Application Analyses and in the site information.

Additional cost information can be found in the Hazardous, Toxic, and Radioactive Wastes (HTRW) Historical Cost Analysis System (HCAS) developed by Environmental Historical Cost Committee of Interagency Cost Estimation Group.


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Innovative Remediation Technologies:  Field Scale Demonstration Project in North America, 2nd Edition

Abstracts of Remediation Case Studies, Volume 4, June 2000, EPA 542-R-00-006

Guide to Documenting and Managing Cost and Performance Information for Remediation Projects - Revised Version, October, 1998, EPA 542-B-98-007

AATDF, 1997. Technology Practices Manual for Surfactants and Cosolvents, Technical Report, Document No. TR-97-2.

DOE, 1994. Technology Application Analysis: Pump and Treat of Contaminated Groundwater at U.S. Department of Energy Kansas City Plant Kansas City, Missouri, prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Technology Application Analysis: Pump and Treatment System at Commencement Bay, South Tacoma Channel (Well 12 A) Phase 2, Tacoma, Washington, prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Technology Application Analysis: Pump and Treat of Contaminated Groundwater at Langley Air Force Base, Virginia, prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Technology Application Analysis: Pump and Treat of Contaminated Groundwater at U.S. Department of Energy, Lawrence Livermore National Laboratory, Livermore Site, Livermore, California, prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Technology Application Analysis: Pump and Treat of Contaminated Groundwater at Operable Unit B/C, McClellan Air Force Base, California, prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Technology Application Analysis: Pump and Treat of Contaminated Groundwater at Operable Unit D, McClellan Air Force Base, California , prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Technology Application Analysis: Pump and Treat of Contaminated Groundwater at Twin Cities Army Ammunition Plant, New Brighton, Minnesota, prepared by Stone & Webster Environmental Technology & Services.

DOE, 1994. Abstract: Pump and Treat of Contaminated Groundwater at U.S. Department of Energy Savannah River Site, Aiken, South Carolina, prepared by Stone & Webster Environmental Technology & Services

EPA, 1988, Guidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA, OSWER- 9355.3-01, Washington, DC

EPA, 1988, Guidance on Remedial Actions for Contaminated Groundwater at Superfund Sites, EPA/540/G-88/003.

EPA, 1989, Evaluation of Groundwater Extraction Remedies OSWER, Washington, DC

EPA, 1989. Performance of Pump-and-Treat Remediations, EPA/540/4-89/005.

EPA , 1990. A Guide to Pump and Treat Groundwater Remediation Technology, EPA/540/2-90/018.

EPA, 1992. Chemical Enhancements to Pump-and-Treat Remediation, EPA/540/S-92/001; NTIS: PB92-180074.

EPA, 1996. Surfactant-Enhanced DNAPL Remediation: Surfactant Selection, Hydraulic Efficiency, and Economic Factors, EPA/600/S-96/002.

Federal Remediation Technologies Roundtable, 1995. Remediation Case Studies: Groundwater Treatment, EPA/542/R-95/003.

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: Groundwater Pump and Treat (Chlorinated Solvents), EPA/542/R-98/013

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: Groundwater Pump and Treat (Nonchlorinated Solvents), EPA/542/R-98/014

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: Innovative Groundwater Treatment Technologies, EPA/542/R-98/015.

Keely, J.F., 1989. "Performance of Punp-and-Treat Remediations," EPA/540/4-89/005.

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Site Information:

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Points of Contact:

General FRTR Agency Contacts

Technology Specific Web Sites:

Government Web Sites

Non Government Web Sites

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Vendor Information:

A list of vendors offering Water Containment Treatment is available from  EPA REACH IT which combines information from three established EPA databases, the Vendor Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and Characterization Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give users access to comprehensive information about treatment and characterization technologies and their applications.

Government Disclaimer

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Health and Safety:

Hazard Analysis

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