Sponsored by Kerfoot Technologies, Inc.

Managing Uncertainty: Perozone Sparging Under a Fixed-Price Contract
Christopher J. Watt, LACO Associates-Consulting Engineers

In-Situ Remediation of Hydrocarbons and MTBE in a Low-Yielding Aquifer - A Practical Approach
Daniel P. Cusick, P.G., Conestoga-Rovers & Associates, Inc., Pittsburg, PA

Securing MNA with Perozone®-Mediated Source Control Combined with Molecular Diagnostics
Matthew Burns, WSP Environmental Strategies LLC, Boxborough, MA

Rapid Source Reduction by Coated Microbubble Injection at a Former Wood-Treating Site
J. Geoffrey Gay, MACTEC Engineering and Consulting, Inc., Kennesaw, GA

Effective Removal of Recalcitrant Contaminants Using Peroxide-Coated Ozone Microbubbles
William B. Kerfoot, Kerfoot Technologies, Inc., Mashpee, MA

Managing Uncertainty: Perozone Sparging Under a Fixed-Price Contract

Christopher Watt and Franziska von Herrath, LACO ASSOCIATES, 21 West Fourth Street, CA , 95501 , Tel: 707-443-5054, Fax: 707-443-0553, Email: wattc@lacoassociates.us, vonherrathf@lacoassociates.us 

Characterization of hazardous material releases has historically been performed with the purpose of developing a conceptual model of the hydrogeologic, chemical, and physical parameters of a site area.  More recently, an approach is being used which incorporates an assessment of parameters which affect remediation design (EPA Triad).  In general, for remediation designs to be implemented successfully they must account for the inherent uncertainty the site conceptual model.  It is our claim that the development and commitment to a fixed-price performance-based contract requires tools to manage uncertainty: these tools are pilot studies, flexible design, and process optimization.

A pilot study can be used evaluate the performance of several remedial methodologies which can be used to develop a remediation conceptual model.  Flexibility in system design allows for multiple remediation technologies to be exchanged in order to maintain cost effective mass removal rates as removal rates decrease over time.  When combined with acquisition of real-time performance data acquisition to optimize system performance, the uncertainty around maintaining cost effective operations is managed.  This opens the opportunity for a remediation practitioner to enter into a fixed-price performance-based contract with a greater degree of certainty to achieve project results on time and within budget. 

We will discuss the advantages and risks associated with fixed-price performance-based contracts and explain the application of tools to manage uncertainty as part of several case studies.

In-Situ Remediation of Hydrocarbons and MTBE in a Low-Yielding Aquifer - A Practical Approach

Daniel P. Cusick, Conestoga-Rovers & Associates, Inc., 103 Gamma Drive Extension, Suite 190, Pittsburgh, PA 15238, Tel: 412-963-7313, Fax: 412-963-7314

A subsurface release of unleaded gasoline was discovered at an operating retail gasoline station in southwestern Pennsylvania during due diligence activities conducted in September 2003.  Site characterization activities concluded that dissolved phase unleaded gasoline constituents (specifically benzene, ethylbenzene, naphthalene, and methyl tertiary-butyl ether [MTBE]) were present at concentrations above the Pennsylvania Statewide Health Standards (SHS) Medium-Specific Concentrations (MSC) in the uppermost water-bearing unit underlying the property.  Based on pilot testing results and aquifer characterization properties, traditional remediation techniques (i.e., vacuum extraction, pump & treat, etc.) with ex-situ treatment were determined not to be feasible for this low-yielding unconsolidated aquifer.  Supporting evidence of biodegradation was present; however, anoxic conditions (i.e., oxygen depleted) were present in the aquifer, and the availability of electron acceptors was limited in areas of constituent impact.  Ozone sparging with enhanced bioremediation was determined to be a practical, cost-effective remedial technique for the site conditions. The ozone sparging treatment process consists of a combination of chemical oxidation destruction (primary remedial mechanism), followed by enhanced natural bioremediation (secondary remedial mechanism).  A Kerfoot Technologies, Inc. C-Spargerâ unit was installed with ozone distributed through seven spargepoints that began operations in July 2005.  Reductions in benzene concentrations from a maximum of 4,400 micrograms per liter (mg/L) to less than the SHS MSC (5 mg/L) have been achieved for groundwater within approximately 19 months.  MTBE (maximum 2,600 mg/L), ethylbenzene (maximum 3,000 mg/L), and naphthalene (maximum 840 mg/L) have all been reduced to concentrations below the SHS MSC or laboratory detection limits within approximately 12 months of system operation.   The project is approaching closure through a risk-based approach with an active remediation life cycle of only approximately two years with minimal operations and maintenance.

Securing MNA with Perozone®-Mediated Source Control Combined with Molecular Diagnostics

Matthew Burns, WSP Environmental Strategies LLC, 1740 Massachusetts Avenue, Boxborough, MA 01719, Tel:  978-635-9600, Fax:  978-264-0537, Email:  matt.burns@wspgroup.com
Stephen Koenigsberg, WSP Environmental Strategies LLC, 4199 Campus Drive, Suite 550, Irvine, CA 92612, Tel:  949-725-2972, Fax:  949-725-2973, Email: stephen.koenigsberg@wspgroup.com

A historic release of coolant containing chlorinated solvent has lead to a 1200-foot long dissolved volatile organi c c ompound (VOC) plume at central Georgia manufacturing facility. Site characterization showed a continuing vadose zone source, elevated dissolved VOC concentrations in the source area (50 mg/l), temporally decrea sin g VOC concentrations, and evidence of chlororespiration.   Application of molecular biological tools (MBTs), primarily the use of quantitative polymerase chain reaction (qPCR) taxonomic and functional gene analysis conclusively demonstrated that Dehalococcoide s s pp (DHC) and key dechlorinating enzymes were present at the site.  This provided evidence to the fact that the plume wa s s table as a result of natural attenuation.    

To minimize the remedial timeframe and gain regulatory approval for monitored natural attenuation (MNA) source area soils and source area groundwater containing VOC concentrations greater than 0.5 mg/l were targeted for active remediation.  Source area soil excavation and groundwater chemical oxidation were the technologie s s elected for these areas of concern.  Perozone® wa s s elected as the chemical oxidant because it does not leave a footprint of oxidized inorganic species that could inhibit chlororespiration such as manganese.  Also, site conditions provided advantages regarding the greater radius of influence of Perozone® as compared to aqueous-phase oxidants.

The integrated remediation approach, defined a s s ource treatment plus MNA, was approved by the Georgia Environmental Protection Division (EPD).  This integrated remediation approach holds in abeyance the additional application of downgradient in-situ bioremediation operations.  The cost of implementing such additional steps is estimated to be anywhere from $700,000 and $1,700,000 depending on the final configuration of in-situ barriers and arrays, should those steps ever be necessary.  

Rapid Source Reduction by Coated Microbubble Injection at a Former Wood-Treating Site

J. Geoffrey Gay, MACTEC Engineering and Consulting, Inc., 3200 Town Point Drive, Suite 100, Kennesaw, GA 30144, Tel:  770-421-3348, Fax: 770-421-3486
Andrew Brolowski, Kerfoot Technologies, Inc., 766-B Falmouth Road, Mashpee, MA  02649, Tel:  508-539-3002, Fax: 508-539-3566

This RCRA site has been involved with an extensive source control/remediation pump and treat from a nine recovery well system.  Although contamination has been reduced significantly during the past 10 years, the decision was made to test in situ oxidation of a source area with an ozone/peroxide (Perozone®) system.

The pilot test area contained fine to coarse sand and gravel with clay and silt layers. To 60 feet below ground surface with heavily-contaminated PAH soils and groundwater.  Water table lay in a capping formation of organic clay and silt with peat.  Analyses showed initial COD of 15,700 mg/kg soil (38-45 ft.) to 1,110 mg/kg (58-60 ft.).  Total organic carbon (TOC) ranged from 1005 (38-45 ft.) to 127 mg/kg (58-60 ft.).  Total PAH concentrations ranged from 1005 (38-45 ft. bgs) to 0.67 mg/kg (58-60 ft bgs).  Concentrations of dissolved PAHs ranged from 1.19 to 3.6 mg/L from monitoring wells.

The pilot test was conducted for 60 days.  Dissolved naphthalenes rapidly decreased with a half-life (time to ½ concentration) of 12 to 20 days (PMWs-1A, 2B, 2A, 2B, 6A).  From 93 to 99% removal in aqueous phase was found in the nearby monitoring wells.  Previous laboratory testing had indicated a 5 to 1.0 mass ratio (ozone to naphthalene) would be necessary.  A field ratio of 3 to 1 was delivered.  The rate of removal exceeded the computer projection.

Effective Removal of Recalcitrant Contaminants Using Peroxide-Coated Ozone Microbubbles

William B. Kerfoot, Kerfoot Technologies, Inc., 766-B Falmouth Road, Mashpee, MA 02649, Tel:  508-539-3002, Fax:  508-539-3566
A.M. Scheffer, Verhoeve Milieu bv, Dorpsstraat 32, 6999 AD Hummelo, The Netherlands, Tel:  011-31-314 38 93 23, Fax:  011-31-314 62 49 44
Edward van de Ven, Verhoeve Milieu bv, Adventurijn 600, 3316 LB Dordrecht, The Netherlands

Chloroalkanes like dichloroethane (DCA) and chloroform (CF) and also pesticides are normally considered as reluctant to recalcitrant contaminants for treatment by ISCO. This presentation shows two case studies about the effective treatment with the Perozone®-system of the apparently recalcitrant contaminants.

The chloroalkanes (mainly chloromethanes and chloroethanes) were present on a industrial site together with chloroethenes, xylenes and monochlorobenzene. Prior to the application of Perozone® , excavation and P&T were used for removal of the contaminants. After about six years of P&T the remediation stagnated in 2001 probably due to sorbed fractions or through slow mass delivery from a humic intervening layer. After some investigations Perozone® was selected to treat the remaining contamination and was started in September 2005. Upon start DCA and CF were found in maximum concentrations of 1,900 and 2,200 µg/l, respectively. The groundwater concentrations are lowered to about 150 µg/l and 20 µg/l after 9 months of treatment, i.e. efficiencies of respectively 92 and 99%.

Perozone® is also used on a other industrial site where MCPP, a organic herbicide (common name: Mecoprop) was found in groundwater. A bench-scale test showed that MCPP was treated succesfully using a combination of ozone and hydrogen peroxide. A 9-week pilot test was done to study the possibilities of Perozone® for in-situ treatment of MCPP in groundwater. The pilot test was set up with a 3-well system in triangular setup. As common for pesticides the groundwater concentrations were low, 55 µg/l of MCPP at the start of the pilot test . After startup of the pilot test mobilization was found and the concentrations raised to a maximum of 170 µg/l. In the most monitoring wells within the “injection triangular” the concentrations decreased to below 0.5 µg/l (the regulatory MCL) and resulted in a overall removal of 87% in 9 weeks of treatment, representing quick and effective removal of an uncommon organic pesticide.

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