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Remediation Technologies Screening Matrix, Version 4.0 4.38 Hydrofracturing
(In Situ GW Remediation Technology)
  Description Synonyms Applicability Limitations Site Information Points of Contact
Data Needs Performance Cost References Vendor Info. Health & Safety
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Technology>>Ground Water, Surface Water, and Leachate

>>3.10 In Situ Physical/Chemical Treatment

      >>4.38 Hydrofracturing
Introduction>> Injection of pressurized water through wells cracks low permeability and over-consolidated sediments. Cracks are filled with porous media that serve as substrates for bioremediation or to improve pumping efficiency.

Description:


Figure 4-38:
Typical Sequence of Operations for Creating Hydraulic Fractures  

Hydrofracturing is a pilot-scale technology in which pressurized water is injected to increase the permeability of consolidated material or relatively impermeable unconsolidated material. Fissures created in the process are filled with a porous medium that can facilitate bioremediation and/or improve extraction efficiency. Fractures promote more uniform delivery of treatment fluids and accelerated extraction of mobilized contaminants. Typical applications are linked with soil vapor extraction, in situ bioremediation, and pump-and-treat systems.

The fracturing process begins with the injection of water into a sealed borehole until the pressure of the water exceeds the overburden pressure and a fracture is created. A slurry composed of a coarse-grained sand and guar gum gel or a similar substitute is then injected as the fracture grows away from the well. After pumping, the sand grains hold the fracture open while an enzyme additive breaks down the viscous fluid. The thinned fluid is pumped from the fracture, forming a permeable subsurface channel suitable for delivery or recovery of a vapor or liquid.

The hydraulic fracturing process can be used in conjunction with soil vapor extraction technology to enhance recovery. Hydraulically-induced fractures are used to deliver fluids, substrates and nutrients for in situ bioremediation applications.

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Synonyms:

DSERTS Code: F17 (Hydrofracturing - enhancement)

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Applicability:

Hydrofracturing is applicable to a wide range of contaminant groups with no particular target group.

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Limitations:

Factors that may limit the applicability and effectiveness of the process include:
  • The technology should not be used in bedrock susceptible to seismic activity.
  • Investigation of possible underground utilities, structures, or trapped free product is required.
  • The potential exists to open new pathways leading to the unwanted spread of contaminants (e.g., DNAPLs).
  • Pockets of low permeability may still remain after using this technology.
  • There is an inability to control the final location or size of the fractures that are created.
  • Fractures are anticipated to collapse due to over burden pressure.

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Data Needs:

A detailed discussion of these data elements is provided in Subsection 2.2.2. (Data Requirements for Ground Water, Surface Water, and Leachate).

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Performance Data:

The technology has had widespread use in the petroleum and water-well construction industries but is an innovative method for remediating hazardous waste sites.

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Cost:

The cost per fracture is estimated to be $1,000 to $1,500, based on creating four to six fractures per day. This cost (including equipment rental, operation, and monitoring) is small compared to the benefits of enhanced remediation and the reduced number of wells needed to complete the remediation. A number of factors affect the estimated costs of creating hydraulic fractures at a site. These factors include physical site conditions such as site accessibility and degree of soil consolidation; degree of soil saturation; and geographical location, which affects availability of services and supplies. The first two factors also affect the effectiveness of hydraulic fracturing.

The costs presented in this analysis are based on conditions found at the Xerox Oak Brook site. A full-scale demonstration was not conducted for this technology. Because operating costs were not independently monitored during the pilot-scale demonstrations at the Xerox Oak Brook and Dayton sites, all costs presented in this section were provided by Xerox and University of Cincinnati Center Hill.

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References:

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

EPA, 1991. Feasibility of Hydraulic Fracturing of Soil to Improve Remedial Actions, EPA/600/S2-91/012.

EPA, 1993. Hydraulic Fracturing Technology, EPA/600/R-93/505.

EPA, 1993. Hydraulic Fracturing of Contaminated Soil, series includes Demonstration Bulletin, EPA/540/MR-93/505; Technology Evaluation and Applications Analysis Combined, EPA/540/R-93/505; and Technology Demonstration Summary, EPA/540/SR-93/505.

EPA, 1994. In Situ Remediation Technology Status Report: Hydrofracturing/Pneumatic Fracturing, EPA/542/K-94/005.

EPA, 1997. Analysis of Selected Enhancements for Soil Vapor Extraction, EPA OSWER, EPA/542/R-97/007.

Federal Remediation Technologies Roundtable, 1997. Remediation Case Studies: Soil Vapor Extraction and Other In Situ Technologies, EPA/542/R-97/009.

Hubbert, M.K and D.G. Willis, 1957. "Mechanics of Hydraulic Fracturing," Petroleum Transactions AIME, Vol. 210, pp. 153 through 168.

Murdoch, L.C., 1990. "A Field Test of Hydraulic Fracturing in Glacial Till," in Proceedings of the Research Symposium, Ohio, EPA Report, EPA/600/9-90/006.

Murdoch, L.C., 1993. "Hydraulic Fracturing of Soil During Laboratory Experiments, Part I: Methods and Observations; Part II: Propagation; Part III: Theoretical Analysis", Geotechnique, Vol. 43, No. 2, Institution of Civil Engineers, London, pp. 255 to 287.

University of Cincinnati (UC), 1991. "Work Plan for Hydraulic Fracturing at the Xerox Oak Brook Site in Oak Brook, Illinois".

Wolf, A. and L.C. Murdoch, 1992. "The Effect of Sand-Filled Hydraulic Fractures on Subsurface Air Flow: Summary of SVE Field Tests Conducted at the Center Hill Research Facility", UC Center Hill Facility, Unpublished Report.

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Site Information:

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Points of Contact:

General FRTR Agency Contacts

Technology Specific Web Sites:

Non Government Web Sites

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Vendor Information:

A list of vendors offering In Situ Physical/Chemical Water 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:

To be added

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