Fracturing
Application
A-Zone Aquifer ZVI Permeable Reactive Barrier Project, Hookston Station Site, Pleasant Hill, California: Final Construction Report
GeoSierra Environmental, Inc.
California Regional Water Quality Control Board, San Francisco Bay Region. 45 pp, Sep 2009
An iron PRB was installed in 2009 at an off-site location near the Hookston Station site to degrade TCE, cis-1,2-DCE, VC, and 1,1-DCE in site groundwater and limit their migration downgradient. Constructed using azimuth-controlled vertical hydrofracturing technology, the PRB consists of one continuous reactive zone of ZVI ~480 feet in length and ~32 feet in vertical height.
Evaluation of the Propagation of Secondary Fractures from Hydraulic Fracture and Injection to Create a Treatment Zone in Low Permeability Fractured Clay Soils
Peace, C. and L.M. Austrins.
REMTECH 2010: The Remediation Technologies Symposium, Banff, AB, Canada, 20-22 Oct 2010. Environmental Services Association of Alberta, Edmonton, AB (Canada), 29 slides, 2010
At the site of a chemical production plant in operation since the 1950s, the subsurface was contaminated with a variety of chlorinated VOCs (unspecified). A soil fracturing and injection pilot study was carried out in a low-permeability, fractured silty clay till to introduce slow-release amendment into secondary fractures and create a remedial diffusion halo into the surrounding low-permeability clay till. Quantifying the propagation and relative location of secondary fractures, as well as determining the effective treatment zone, was a primary metric for successful application. A total of six locations at three depths, 12, 15, and 18 ft bgs were fractured, and a mixture of guar, ZVI, glycol, and breaker solution was injected. Effective emplacement in the treatment area occurred and was quantified spatially. This successful pilot allowed for the optimization of fracture geometry before implementation at a larger scale, and the technique has been applied to several other areas of the site.
Fracture-Emplacement and 3-D Mapping of a Microiron/Carbon Amendment in TCE-Impacted Sedimentary Bedrock
Bures, G.H., J.A. Skog, D. Swift, J. Rothermel, R. Starr, and J. Moreno.
Proceedings of the Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2010). Battelle Press, ISBN: 978-0-9819730-2-9, Paper & presentation D-067, 9 pp + 23 slides, 2010
An in situ pilot remediation project was carried out on behalf of the U.S. Army Corps of Engineers (Omaha District) at the F.E. Warren AFB in Colorado. The pilot featured an innovative application of drilling, fracture emplacement, treatment, and geophysical technologies to mitigate impacts from chlorinated solvents. The former missile site complex is underlain by silty sandstone bedrock sediments affected by TCE >2,000 µg/L and associated VOCs. Pilot tests of biotic and abiotic in situ chemical reduction (ISCR) were conducted in the source area and dissolved plume to evaluate technology performance prior to developing the proposed remedy. The pilot involved the emplacement of over 100 tons of EHC™, a micro-iron/complex-carbon treatment amendment, into deep bedrock sediments to attain optimal distribution throughout the contaminant plume, including beneath the former Launch and Service Building. The radius of fracture emplacement in the bedrock was up to 60 ft, with a typical fracture overlap of 30 to 50%. Following placement of the amendment, physical, chemical, and microbiological processes combined to create very strong reducing conditions that stimulated chemical and microbiological dehalogenation of the contaminants. View longer abstract. Additional information: Presentation Slides
, Field Profile
Hydraulic and Pneumatic Fracturing Demonstrated at U.S. Department of Energy Portsmouth Gaseous Diffusion Plant, Ohio, and Department of Defense and Commercial Sites
1998. DOE/EM-0348.
Hydraulic and pneumatic fracturing induce fractures in the subsurface to enhance the remediation of contaminants both above and below the water table. This cost and performance case study covers demonstrations that were conducted between July 1991 and August 1996.
In Situ Chemical Oxidation in Clays Using Hydraulic Fracturing
Bures, G.H., T.J. Williams, E. Mance, and C. Clark.
Proceedings of the Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2010). Battelle Press, ISBN: 978-0-9819730-2-9, Paper & presentation D-085, 8 pp & 21 slides, 2010
A soil fracturing program was conducted at a former dry cleaning facility to mitigate PCE and its daughter products to risk-based soil and groundwater remediation criteria by enhancing the zone of influence of peroxidants injected through permeable sand fractures in the clay subsoil. Following two unsatisfactory applications of modified Fenton's reagent into the fracture network (32% PCE decrease on average), potassium permanganate slurry was injected into the fracture network on six occasions during 2007, followed by 12 injections of sodium permanganate in 2008 and 2009. Sampling results as of August 27, 2009, indicated that PCE concentrations had decreased on average by 95% in wells inside the perimeter of the plume and 78% in wells centered in the core of the plume. With a general decrease in soil PCE concentrations, the quantity of soil classified as hazardous fell by ~62% across the site. Ongoing peroxidant injections are anticipated to destroy chlorinated constituents that leach from core area clays into the fracture network.
In Situ Remediation Technology Status Report: Hydrofracturing/Pneumatic Fracturing
EPA 542-K-94-005 , 1994
Describes field demonstrations or full-scale applications of in situ abiotic technologies for nonaqueous phase liquids and ground water treatment.
Methods for Enhanced Delivery of In Situ Remediation Amendments in Contaminated Clay Till
Camilla Maymann Christiansen, Ph.D. thesis, Technical University of Denmark, Kgs. Lyngby, ISBN: 978-87-91855-88-7, 86 pp, 2010
A field study was conducted at a site in Denmark from March 2006 to March 2010 to test and document the capabilities of three enhanced delivery methods—pneumatic fracturing, hydraulic fracturing, and direct-push delivery—in clay till at depths of 2.5 to 9.5 m bgs. The focus was on the delivery of in situ remediation amendments in clay till rather than on the contaminants themselves or the amendments developed for their treatment. Direct documentation at depth was largely confined to coring but was supplemented by excavation at shallow depths. This work describes the findings and unresolved issues from the 4-year study.
Multiphase Approach to Remediation Using Subsurface Fracturing, Surface Extraction and Modified Fenton Chemistry
Owens, D.C., Oxy Teknologies.
REMTECH 2010: The Remediation Technologies Symposium, Banff, AB, Canada, 20-22 Oct 2010. Environmental Services Association of Alberta, Edmonton, AB (Canada), 14 slides, 2010
ISCO with modified Fenton chemistry in conjunction with subsurface fracturing and surface extraction was conducted to remediate 11,325 cubic meters of diesel- and gasoline-contaminated soil and groundwater at a trucking terminal operated 24 hour per day without disrupting terminal operations. Free-phase liquid petroleum hydrocarbons (LPH) covered an area extending ~1,100 square meters. Subsurface fracturing was effective in about half the contaminated area and showed no significant results in the other half. Costs were high compared to the added value of the fracturing. The unpredictability of fracturing routes and fracture diffusion also are problems with this technology. Surface extraction of LPH was limited by cold surface conditions, limited fracturing effectiveness, and seasonality of the water table; overall, the method gave results equal or superior to pump and treat at significantly lower costs. ISCO with stabilized hydrogen peroxide was very effective in degrading the LPH in free, dissolved, and absorbed phases. The limiting factor was the ability to get the oxidant into contact with the LPH due to the tight soil conditions. Working conditions were difficult. Undermining the asphalt during ISCO was an ongoing problem but was handled with spot repairs. Winter conditions were also a limiting factor because of the difficulty of locating injection wells in snow and ice. The methods used in this remediation project resulted in cost savings of roughly $2.3 million when compared to standard dig and haul, plus an additional $3.6 million in potential relocation and lost business costs for a total savings of $5.9 million. In 10 months of treatment, the average thickness of LPH decreased 94%, while total dissolved-phase PHCs fell by 96%, demonstrating that a multi-phased remediation approach can provide remediation without disruption to an operating facility.
Oxidant Dispersal in Tight Clay Formations Using EK3 Technology
Frisky, S.
REMTECH 2010: The Remediation Technologies Symposium, Banff, AB, Canada, 20-22 Oct 2010. Environmental Services Association of Alberta, Edmonton, AB (Canada), 46 slides, 2010
EK3 is a process in which a low-voltage DC electric field is applied across a section of clay soil to disperse a water/chemical oxidant mixture within the formation, primarily via electroosmosis. Combining EK3 technology with injection wells, clay fracturing, and injection of chemical oxidant can increase the efficiency and effectiveness of chemical oxidant dispersion significantly. In a pilot project located in Regina (Canada), the EK3 technology is used to disperse a water/chemical oxidant mixture throughout a test plot of tight clay soil to treat hydrocarbon contamination. In addition to hydrocarbons remediation, the technology can be used to address contaminating salts and metals as described in an article posted by National Research Council Canada.
Record of Decision: Valmont TCE Superfund Site, Luzerne County, Pennsylvania
U.S. EPA Region 3, 151 pp, 2011
In situ treatment of the entire groundwater plume (TCE predominating) will be done by batch injection of a chemical oxidant (e.g., potassium or sodium permanganate) into the bedrock. EPA conducted a pilot study at the site between 2008 and 2010 to evaluate ISCO effectiveness as a stand-alone remedy by injecting a high volume (26,000 lbs) of potassium permanganate slurry into the fractured bedrock. Permanganate was injected as a slurry to increase oxidant residence time within the bedrock fractures and allow continued reaction with VOCs diffusing from the bedrock matrix. Delivery of the slurry was facilitated through pathways opened by hydraulic fracturing. The fracturing process dilated existing bedrock fractures and flushed fine-grained material from the fractures, thus allowing greater volumes of slurry to enter. Results indicated that the residence time of permanganate in the aquifer exceeded 6 months and achieved significant destruction of VOCs in the source area and in the plume. The radius of influence of slurry injection exceeded 160 ft. Additional information: Technology News & Trends, Dec 2010
Remediation of DNAPLs in Low Permeability Soils: Innovative Technology Summary Report
2000. U.S. DOE, Office of Environmental Management, Subsurface Contaminants Focus Area. Report No: DOE/EM-0550, 36 pp.
Steam and Electroheating Remediation of Tight Soils
1999. Balshaw-Biddle, K.; C.L. Oubre; C.H. Ward, Lewis Publishers, Boca Raton, FL. ISBN: 1566704650, 448 pp.
X-231A Demonstration of In-Situ Remediation of DNAPL Compounds in Low Permeability Media by Soil Fracturing with Thermally Enhanced Mass Recovery or Reactive Barrier Destruction
1998. R.L. Siegrist, et al. ORNL/TM--13534, NTIS: DE98058134, 300 pp.
A set of four test cells was established at the X-231A land treatment unit in August 1996, and a series of field activities occurred through December 1997 to demonstrate soil fracturing with thermally enhanced mass recovery or horizontal barrier destruction in situ. Available through the DOE Information Bridge.
