Projects

GeoSierra Environmental’s controlled placement technologies have been applied in a multitude of scenarios:

  • Sites where trenching is not an option, i.e. deep PRB installations installed greater than 100 feet bgs;
  • Shallow sites with complexities such as highly trafficked streets congested with underground and overhead utilities or even within active railroad right-of-ways;
  • Enhancements to existing pump & treat systems or conventional systems such as SVE or DPE that have reached asymptotic levels;
  • Tight lithologies that require multiple amendment injections, i.e., ISCO or ISCR.

Below is a list of our completed projects. Feel free to contact us for additional site information or project summaries.

2017 Pneumatic Fracturing – EW Enhancement

Southern California

GeoSierra Environmental conducted pneumatic fracturing of an existing extraction well network at a former aerospace testing site. Pneumatic fracturing was selected to enhance the permeability of existing bedrock fractures at two new locations with the objective of connecting to existing extraction wells. The current system was not operating optimally due to the tight granite bedrock and sparse fracture network at depth. Two new locations were drilled to a depth of 110 feet bgs using HSA and air rotary methods and were constructed of a steel casing to competent bedrock and open borehole to depth. After drilling, both locations were geophysical logged to locate fracture intervals and determine target depths. GeoSierra Environmental then used a radial injection nozzle positioned within a straddle packer assembly to target a 42 inch vertical interval and compressed nitrogen gas to open existing fractures and extend the fracture radius. An average pressure of 540 psi was required to initiate the fracture followed by an average of 400 psi maintenance pressure. Thirty-two fractures were completed between both boreholes, resulting in a radius of influence of 30 to 90 feet, depending on the fracture well and the depth. The achieved radius of influence was confirmed using downhole pressure transducers and visual observations at existing monitoring wells, where the transducers measure pressure and temperature changes, confirming connectivity. Upon completion of fracturing activities, the client retrofitted the two fracture wells to extraction wells.

2016 Pneumatic Fracturing/Multi-Azimuth - Bioremediation

Whippany, NJ

GeoSierra Environmental was contracted to conduct pneumatic fracturing for permeability enhancement at a former manufacturing facility within a delineated groundwater hot spot of VOCs. The original design consisted of directional pneumatic fracturing, coupled with frac sand emplacement to sustain fracture apertures prior to retrofitting the fracture points to permanent injection wells for lactate delivery. Difficulties in maintaining a tight seal around the nozzle and suspension of the fracture for sand emplacement were experienced due to the dense till. GeoSierra Environmental modified the permeability enhancement program to vertical hydraulic fracturing for frac sand injection, creating inclusions in parallel rows and orthogonal connections in the hot spot. Nineteen injection wells containing one patented expansion casing were installed using sonic drilling methods. Upon completion of drilling activities, GeoSierra Environmental injected 45 tons of 20/40 frac sand, reaching fracture lengths upwards of 50 feet. After multi-azimuth injections were completed, the client installed monitoring wells and deep aquifer injection wells for subsequent lactate injection and conducted baseline groundwater sampling. GeoSierra Environmental remobilized to the site and injected 33,000 gallons of 2% EVO solution and anaerobic chase water in the 19 previously fracked locations and 12,500 gallons of 2% and 5% EVO solution in the deep wells. Connection in both the deep and shallow wells was observed during injection activities and groundwater monitoring is ongoing.

2016 ZVI-PRB

Glenville, NY

GeoSierra Environmental was contracted to install two trenchless ZVI-PRBs at a federal facility for treatment of a TCE plume. The shallow PRB was 250 linear feet, targeting 65 to 75 feet bgs, and the deep PRB was 700 feet long, targeting 65 to 110 feet bgs - both with a nominal 3-inch thickness. A complete design program was executed, including column treatability testing, hydraulic pulse interference testing, custom testing of the guar-crosslinker-enzyme mixture, Monte-Carlo probabilistic design process and detailed design specifications, which was subsequently approved by the US Army Corps of Engineers and NY State Department of Environmental Conservation. HPIT testing confirmed that two distinct lithologies exist with an order of magnitude difference in groundwater flow velocity. The design was modified to 6-inches from 65 to 80 feet bgs for the full 900 linear feet while maintaining 3-inches for the 80 to 110 feet bgs interval in the deep PRB. Due to the higher groundwater flow velocity, the injection well spacing was modified from 15 to 12 feet to minimize potential loss to the formation. Upon approval of the design, 77 specialized injection wells with one to three patented expansion casings per well and 31 customized subsurface receivers were installed for placement of the vertical PRB and monitoring system. Both PRBs were installed utilizing vertical inclusion propagation to emplace 1,150 tons of ZVI at a rate of approximately 10 tons/day. Post-installation hydraulic pulse interference testing was conducted to confirm that the PRB installation did not adversely affect groundwater flow velocity. Groundwater sampling is ongoing.

2016 Pneumatic Fracturing – SVE Enhancement

Stockton, CA

GeoSierra Environmental was contracted to utilize directional pneumatic fracturing to enhance vadose zone soils prior to installation of a soil vapor extraction system at the DDJC-Sharpe Depot Site. This methodology was selected based upon previously implemented and successful projects using directional pneumatic fracturing to enhance existing and newly installed soil vapor extraction systems by the GeoSierra Environmental management team. The previously fractured sites resulted in site closures after only 2 to 3 years of SVE operation. A directional nozzle was used to target isolated depth intervals and fracture direction, targeting the plume configuration. Continuous coring was conducted at each location prior to installation of the nozzle to identify tight lithology for fracturing. Each location was either fractured in two or four directions to specifically target the treatment area impacted with chlorinated solvents. A total of 126 directional fractures at 23 locations were performed between 7 and 14 feet bgs in one week of field time. QA/QC monitoring was eliminated from the fracture program due to the repetitive demonstration of consistently achieving a radius of influence of 15 to 25 feet in similar geology. After demobilization from the site, the fracture points were retrofitted to soil vapor extraction wells and monitoring is ongoing.

2015 HPIT – Slurry Wall

Wilmington, MA

GeoSierra Environmental conducted a second phase hydraulic pulse interference testing of a previously installed slurry wall containment system. This phase supplemented previous testing conducted in 2012 and was scheduled during seasonably high water elevations. New wells were installed and included for testing, considering limitations identified in Phase One such as well pair distance and well construction. Several well pairs from Phase One were also repeated. Hydraulic pulse interference tests involve a cyclic injection of fluid into the source well, and by high precision measurement of the pressure pulse in a neighboring well, detailed hydraulic characterization between wells can be made. GeoSierra Environmental mobilized the testing and monitoring equipment to again test the hydrogeology between wells including well pairs located inside, outside and through the containment system alignment. Following testing, the data was reduced and graphed and compared to previous testing. When compared to Phase One, not all the wells were ideal for pulse interference testing due to their construction resulting in some invalidated data. Final conclusions determined that the distance between well pairs was a limiting factor as it would only provide a pinpointed verification of the integrity of the slurry wall and that further testing is warranted in a stepwise approach at alternate but closer distances.

2015 HPIT – Extraction System

Queens, NY

GeoSierra Environmental was contracted to hydraulically test well pairs for future installation of extraction wells for a pump and treat system at a Brownfields site that was under active construction. To determine the in-situ hydraulic conductivity and specific storage, a hydraulic pulse interference testing program was designed and implemented using well pairs spaced at varying distances. In order to obtain consistent data, the same source well was used for testing. Hydraulic pulse interference tests involve a cyclic injection of fluid into a source well, and by high precision measurement of the pressure pulse in neighboring wells, detailed hydraulic characterization between wells can be made. GeoSierra Environmental mobilized the testing and monitoring equipment to test the hydrogeology between three well pairs, ranging in distance between 10 and 40 feet. The raw data was reduced and graphed using standard curve matching procedures and the matched point data was input into a series of equations to determine the K and S of the various well pair alignments. The results were used to recalculate and graph the theoretical response of the receiver through a check program that either verified or invalidated the results. This data was used in conjunction with previous pumping test data to design extraction wells for the site.

2014 Multi-Azimuth ZVI-PRTZ

West Coast

GeoSierra Environmental was selected to assist the Department of Energy with remediating an area of concern to treat a targeted hydrostratigraphic unit contaminated with CVOCs. The remedy involved emplacement of zero valent iron using controlled Vertical Inclusion Propagation aka Vertical Hydraulic Fracturing. The objectives were to improve the overall hydraulic conductivity of the low permeability zone and capillary fringe while promoting the in-situ destruction of the contaminant mass. GeoSierra Environmental’s unique technology was used to create a network of vertical fractures that were propped with ZVI in an orthogonally oriented, dual-azimuth vertical alignment. Patented injection casings were installed to create a crisscross fracture network to improve permeability. The ZVI played a dual role by acting as proppant while simultaneously reductively dechlorinating the CVOCs. GeoSierra Environmental completed a design using a proprietary 2-D fracture model that determined that the fractures within the network needed to be approximately 0.4 to 0.6 inches thick and 30 to 60 feet in length. Nine wells were used to cover the target area and each of the well casings incorporated two vertical expansion casings oriented perpendicular to each other. Field implementation resulted in vertical inclusions approximately 10 feet tall and 40 foot in length with a nominal thickness of 0.75-inches between 55 and 75 feet bgs. A total of 21 tons of ZVI were injected to have a beneficial effect on in-situ chemical reduction of site CVOCs.

2014 ZVI-PRB

Peterborough, NH

GeoSierra Environmental was contracted to install a 350 linear foot trenchless ZVI-PRB at the South Municipal Water Supply Well Superfund Site after initially providing the responsible party with feasibility analysis and design support. The ZVI-PRB was intended to cut off a downgradient plume and replace an ineffective pump and treat system while source area remedial activities are implemented. The feasiblity analysis included a column treatability study to evaluate reaction rates on COCs using commercially available sources of ZVI and flow for potential detrimental geochemical impacts on ZVI porosity. GeoSierra Environmental also completed HPIT to determine aquifer conductivity and storativity. Additional design tasks included a multi-component probabilistic design process, determining that a 3-inch thick ZVI-PRB would be required to treat the impacted water entering the PRB to required MCLs. The PRB was constructed using azimuth-controlled vertical inclusion propagation technology. The PRB is oriented perpendicular to ground water flow and extends from 5 to 50 feet bgs. Thirty-five specialized expansion injection casings were required for installation along the PRB alignment and over 350 tons of ZVI was utilized to construct the PRB. To monitor the PRB installation, GeoSierra Environmental employed active resistivity and post-installation QA consisted of repeating the HPIT to ensure that the hydraulic field has not been affected by the placement of the PRB. Both measures demonstrated proper installation of the wall.

2013 Pneumatic Fracturing/Proppant

Irvington, NJ

Pneumatic fracturing (PF) was used in conjunction with Proppant-In Situ Chemical Oxidation (PF/P-ISCO) treatment at an active manufacturing facility within a hot spot of VOCs in a dense till. Directional PF was selected to emplace a frac sand / potassium permanganate mixture to sustain fractures while providing long-term diffusion of the oxidant within the soil matrix. Prior to mobilization, an evaluation of the existing structure and utilities was conducted since enhancement of soil permeability by fracturing may be accompanied by temporary ground surface deformation. The evaluation identified a one-story masonry building, a fire suppression line and water line as points of concern. Recommendations for structural monitoring and allowable structural tolerances were finalized prior to mobilization. Five fracture/injection points (FIPs) were installed, targeting 48 fractures between 13 and 20 feet bgs. PF/P-ISCO activities resulted in only 28 fractures completed with frac sand and oxidant slurry due to surface daylighting from a previous excavation. The remaining 20 fractures were completed with only frac sand then all FIP locations were converted to permanent injection points. The remaining granular permanganate was mixed to 1.25% solution and injected into these points. Confirmation sampling identified continuous zones of permanganate at several locations. A post-fracturing structural evaluation was conducted, and all monitoring data was within the acceptable calculated tolerances with no adverse structural or utility influences during PF/P-ISCO activities.

2013 Multi-Azimuth ZVI/Sand

Sacramento, CA

GeoSierra Environmental was contracted to assist with improving the performance of a groundwater P&T system located at McClellan Air Force Base. We recommended multi-azimuth vertical hydraulic fracturing to create a fracture network of ZVI and 20/40 frac sand across the area of concern. The frac sand would intercept existing extraction wells for permeability enhancement, while the ZVI would provide permeability enhancement with additional in-situ treatment of the CVOCs. A design program was conducted which included using modified PKN and GDK models that account for fluid losses and site-specific fracture parameters including localized hydraulic conductivity, particle diameter and specific gravity, frac fluid specific gravity, power law parameters and specific geotechnical parameters. Fifty-two individual fracture wells oriented at varying azimuths were installed creating an interconnected grid of vertical fractures across the Site. Each fracture well contained two 5-foot orthogonally oriented casings with the upper casing located at 115 to 120 feet bgs and lower casing at 125 to 130 feet bgs. The azimuth orientations were driven by the goal of linking fractures from within the formation to either adjacent fracture wells, or to link to existing extraction wells across the project site. A total of 70 tons of 20/40 frac sand was placed via the upper casings and over 100 tons of ZVI was distributed into the lower casings. One year following installation, the system experienced approximately a 4 to 5 fold increase in flow rate recovery with one well at a 600% increase in extraction.

2012 HPIT – Slurry Wall

Wilmington, MA

To determine the viability of testing the integrity of a previously installed slurry wall containment system, a hydraulic pulse interference testing program was designed and implemented by GeoSierra Environmental. Hydraulic pulse interference tests involve a cyclic injection of fluid into the source well, and by high precision measurement of the pressure pulse in a neighboring well, detailed hydraulic characterization between wells can be made. To implement the testing of the slurry wall containment system and associated complex hydrogeologic framework, GeoSierra Environmental mobilized the testing and monitoring equipment to test the hydrogeology between wells pairs located inside, outside and through the containment system alignment. The raw data was reduced and graphed using standard curve matching procedures and the matched point data was input into a series of equations to determine the K and S of the various well pair alignments. The results were used to calculate and graph the theoretical response of the receiver through a check program that either verified or invalidated the results. Not all wells tested were ideal for pulse interference testing due to their age and/or construction and distance between well pairs, resulting in some invalidated data. Verified data results indicated that a potential pathway through the slurry wall system may exist and that further testing is warranted to isolate zones of potential containment failures, although this data may be an anomaly due to the underlying shallow bedrock.

2012 ZVI-PRB

Mead, NE

To determine the viability of testing the integrity of a previously installed slurry wall containment system, a hydraulic pulse interference testing program was designed and implemented by GeoSierra Environmental. Hydraulic pulse interference tests involve a cyclic injection of fluid into the source well, and by high precision measurement of the pressure pulse in a neighboring well, detailed hydraulic characterization between wells can be made. To implement the testing of the slurry wall containment system and associated complex hydrogeologic framework, GeoSierra Environmental mobilized the testing and monitoring equipment to test the hydrogeology between wells pairs located inside, outside and through the containment system alignment. The raw data was reduced and graphed using standard curve matching procedures and the matched point data was input into a series of equations to determine the K and S of the various well pair alignments. The results were used to calculate and graph the theoretical response of the receiver through a check program that either verified or invalidated the results. Not all wells tested were ideal for pulse interference testing due to their age and/or construction and distance between well pairs, resulting in some invalidated data. Verified data results indicated that a potential pathway through the slurry wall system may exist and that further testing is warranted to isolate zones of potential containment failures, although this data may be an anomaly due to the underlying shallow bedrock.

2012 Multi-Azimuth Field Test

Medford, NJ

GeoSierra Environmental tested an experimental new oil recovery well completion technique at a site in New Jersey. This first in its kind test included the offsite fabrication and installation of a new, patented 13-inch multi-azimuth controlled vertical inclusion propagation casing to 60 feet bgs; construction and installation of an oilfield bypass wellhead; connection and installation of GeoSierra Environmental’s proppant suspension, mixing and injection system; installation of a surface and downhole 3-Dimensional active resistivity array for inclusion propagation tracking; mixing and injection of a high viscosity hydroxyl propyl guar gel system; and quality assurance and quality control monitoring of injections in real time. GeoSierra Environmental’s injection and support systems and custom electronic QA/QC were mobilized to the site to install and test the new completion technology. Following installation, the shallow inclusions were excavated to confirm the height and thickness of inclusions that propagated to the surface. A total of 27 tons of 20/40 and 12/20 sand proppants were injected in 2 days to create 12 discreet vertical inclusions in multiple directions from the wellhead. Following injections, vertical hydraulic pulse interference testing was completed to confirm coalescence of the inclusions from the upper to the lower casings that resulted in a two order of magnitude increase in well permeability.

2011 ZVI-PRB

Morris Plains, NJ

GeoSierra Environmental installed a 465 foot long iron PRB at a former manufacturing facility along a property boundary to prevent offsite VOC migration. A complete design program was executed, including column treatability testing, hydraulic pulse interference testing, custom testing of the guar-crosslinker-enzyme mixture, Monte-Carlo probabilistic design process and detailed design specifications, which was subsequently approved by the New Jersey Department of Environmental Protection. Following completion of the design, 30 specialized injection wells with two to three patented expansion casings per well and 24 customized subsurface receivers were installed for the placement of the vertical PRB and monitoring system designed to 90 feet bgs. During well installation, GeoSierra Environmental collected continuous split spoon samples and defined the lateral and vertical extents of a glacial channel theorized as a preferential conduit for offsite groundwater migration. Based on this new data, the PRB was extended vertically via additional expansion casings allowing installation of the PRB to 100 feet bgs vs. the 90 feet bgs original design. The PRB was installed between 50 and 100 feet bgs utilizing customized injection, material handling and QA/QC systems. The combination of these unique systems allowed nearly 900 tons of ZVI to be placed in the target zone giving the PRB a nominal thickness of 6 inches with real-time geophysical imaging monitoring the horizontal and vertical extents of inclusion migration to ensure that no gaps or voids existed in the ZVI-PRB.

2008-2009 ZVI-PRB

Pleasant Hill, CA

GeoSierra Environmental installed a 480 linear foot iron PRB within a local park and right-of-way on a highly trafficked main road. The goal was to reduce VOC migration to a residential neighborhood where vapor intrusion was affecting indoor air quality. A complete design consisting of column treatability testing; custom guar, crosslinker and enzyme testing; Monte-Carlo probabilistic design modeling; and detailed design specifications were developed and approved by the California Regional Water Quality Control Board. Following completion of the design, 40 specialized fracture wells and 20 customized subsurface strings with receivers were installed for installation of a vertical hydraulically fractured PRB and monitoring system down to depths of 50 feet bgs. The injection and support systems consisting of two 3,000-gallon stainless steel guar mix tanks, hydraulically controlled injection equipment including centrifugal mixing and transfer pumps, 300-HP diesel power unit, 2,500-psi piston pumps, iron mixing vapor control system, 3,000-lb concrete hoppers and weight control systems, custom electronic QA/QC s and all supporting systems were mobilized to the site to install the PRB from 15 to 50 feet bgs along the alignment. Seven years after PRB installation, six of the eight downgradient wells are less than MCLs and two continue to trend downward. Reports from groundwater monitoring can be obtained from this link. http://geotracker.waterboards.ca.gov/profile_report.asp?global_id=SL601392782

2005 ZVI-PRB

San Antonio, TX

GeoSierra installed two PRBs within 26 feet of an active Union Pacific Railroad (UPRR) line near the former Kelly Air Force Base. The PRB consisted of two segments totaling 1500 feet in length, extending from 20 to 40 feet in depth. The PRB varies in thickness from 3 to 4.5 inches and is comprised of nearly 500 tons of iron. The work zone was located entirely within the UPRR right-of-way, resulting in an access width of less than 25 feet for the PRB construction equipment. The treatment zone consisted of a shallow, perched aquifer with a gravelly layer underlain by a silty clay aquitard (Navarro Formation). The objective of the PRB was to degrade VOCs in the perched groundwater into non-toxic end products and thus stop groundwater migration of those contaminants.

Kelly AFB – Federal Facilities Environmental Journal
Kelly PRB - UPRR
AFCEE Center Views 2004
Kelly AFB – 34th street
Kelly AFB - Commercial

2005 ZVI-PRB

Oakley, CA

GeoSierra installed an extension to the pilot PRB installed in 2001 at the Oakley, CA site. Two full-scale PRBs were constructed. Groundwater at the chemical facility was contaminated with elevated levels of VOCs, primarily carbon tetrachloride, FREON113®, FREON11®, and 1,2-dichloroethane. After installation of the first phase in 2001, sampling of the downgradient monitoring wells verified that contaminant concentrations had decreased by 90%. The second phase PRBs included: 1) an extension of the 110 foot long pilot PRB to a full-scale length of 485 feet at a depth of 60 to 115 feet bgs; and 2) the installation of a shallow 485 foot long PRB, upgradient of the original pilot PRB, from a depth of 25 to 50 feet bgs.

2004 ZVI-PRB

Oklahoma City, OK

GeoSierra completed the installation of a 95 foot deep iron PRB at Tinker AFB, using GeoSierra’s azimuth controlled vertical hydraulic fracturing technology. Thirty-four 6-inch diameter boreholes were drilled every 15 feet along the alignment of the PRB, and fracture casings were placed into the boreholes for injection of iron filings. The constructed PRB was 500 feet in length, with a treatment depth extending 70 to 95 feet bgs with an iron effective thickness of 4.5-inches in the central section of the PRB and 3-inches elsewhere. A total of 340 tons of iron filings was injected into the subsurface to complete the PRB. Six years post-PRB installation, contaminant concentrations continued to trend downward with some locations meeting MCLs.

Tinker Take-off

2002 ZVI-PRB

Montross, VA

An iron PRB system was designed and built by GeoSierra for treatment of groundwater contaminated with VOCs and heavy metals. The PRB was approximately 1,200 feet in length, extended in height from 17 to 45 feet bgs with a nominal thickness of 4-inches. The soils consisted of sands and silts, with extremely loose flowing sands and silts encountered over a 15 feet depth interval. Eight-two injection wells were installed with split spoon samples collected at alternate borings to ensure the PRB was installed into the underlying till unit. A strong iron stone stratum was in the seasonally fluctuating water table. Although moderate in depth, the PRB was installed by GeoSierra’s trenchless construction technology because of the need to minimize spoils.

Design, Construction and Installation Verification of a 1200' Long Iron Permeable Reactive Barrier

2001 ZVI-PRB

Oakley, CA

A pilot PRB was designed and installed by GeoSierra at a former chemical manufacturing facility in the Bay Area, California as an Interim Measure to substantially reduce the source of plume migration to the river. The deep pilot PRB is 6-inches thick and measured 110 feet long, ranging in depth from 45 to 110 feet. The soils consisted of medium to fine silty sands changing with depth to coarse the fine silty sands with little to some fine gravel. The project was completed in January 2001. ENR Magazine (Engineering News Record) published an article about this project in their December 2, 2002 issue.

2000 ZVI-PRB / Horizontal Fracturing/Proppant Injection

Centerville, IA

A manufacturing facility had both TCE contaminated soils and groundwater. The ROD was amended to an enhanced dual phase SVE system for soils and an in-situ iron PRB for groundwater. Site soils consisted of fine lenticular sand lenses and medium river channel sands, overlain and underlain by stiff over consolidated glacial till. GeoSierra installed a fracture enhanced Dual Phase-SVE system under a building at nine locations between grade and 30 feet bgs, extending sand filled fractures to 50 feet in diameter. For groundwater, GeoSierra designed and built an iron PRB with dimensions of 240 feet in length and extending in height from a depth of 25 to 75 feet bgs.

Groundwater Performance Monitoring of an Iron Permeable Reactive Barrier
Deep Reactive Barriers for Remediation of VOCs and Heavy Metals

1997 ZVI-PRB

Fairfield, NJ

GeoSierra designed and constructed a PRB at the Caldwell Superfund Site in a highly geologically complex glacial environment to treat groundwater contaminated with TCE and other VOCs. The system consists of two parallel iron PRBs in the overburden soils, which consisted of an eskar deposit of sands, gravel, and boulders, overlain by clay till. The PRB was 360 feet long and extended in height from approximately 25 to 65 feet bgs. The PRB was extended by an additional 90 feet in mid-1999. The installation of the PRB extension was constructed at record productivity and achieved clean breakdown of the iron-gel mixtures in 1 to 2 hours.

Construction and Performance Monitoring of In Situ Reactive Barriers