Eric Bergeron, Golder Associates, 9200 boulevard de l'Acadie, MontrJal, QuJbec Canada, H4N 2T2, Tel: 514-383-0990 ext. 312, Fax: 514-383-5332. Email: ebergeron@golder.com
Christian Gosselin, HJlPne Richer-BJrard, Martin Beaudoin, Golder Associates, 9200 boulevard de l'Acadie, MontrJal, QuJbec Canada, H4N 2T2
Adriana Peisajovich, Transport Canada, 700 Leigh Capreol, Dorval, QuJbec Canada, H4Y 1G7
Tel: 514-633-3956, Fax: 514-633-3353, Email: peisaja@tc.gc.ca
Ginette Lajoie, Cree Regional Authority, 277, Duke Street, Suite 100, MontrJal, QuJbec Canada, H3C 2M2, Tel: 514-861-5837, Fax: 514-861-5332, Email: glajoie@gcc.ca

Transport Canada used the Nitchequon Site as a meteorological station from 1942 to 1985. The site is located 1600 km north-east MontrJal and is only accessible by hydroplane or helicopter. Several characterizations revealed that the soil was contaminated with hydrocarbons (PH). In situ and ex situ pilot-scale chemical oxidation testing using the following three technologies were investigated: Tecosol in situ process (SOLTEC^Ò), ex situ reactors and in situ passive reactor cells. The main objectives of the study were to evaluate the technical/economical feasibility of using a full-scale chemical oxidation remediation approach for the Nitchequon site and to prepare a preliminary rehabilitation plan including a budgetary cost evaluation and a preliminary schedule for remediation of the Nitchequon site.  The in-situ treatment of the Nitchequon soils using the SOLTEC^Ò technology was ineffective.  The tests performed in continuous mixed reactors achieved interesting removal efficiencies.  The final PH concentration and overall removal efficiency reached in the mixer for the different fractions of PH C₁₀-C₅₀ are the following: C₄-C₁₀ average final concentration of 1,6 ppm (96% reduction), C₁₁-C₁₆ : average final concentration of 690 ppm (86% reduction), C₁₇-C₃₄ average final concentration of 243 ppm (33% reduction), C₃₅-C₅₀ below detection limit and C₁₀-C₅₀ average final concentration of 990 ppm (83% reduction). The mean initial PH C₁₀-C₅₀ concentration was 5975 ppm. The results of the passive rector tests will be available only in spring 2004.  A preliminary rehabilitation plan has been developed.  The proposed approach is to treat the soil with permanganate in horizontals blenders, backfill the excavations with the slurry to complete the chemical oxidations reactions and add a clean cover of soil (0.3 m thickness) over the treated soils.  The total budget (excluding taxes) to perform the full-scale rehabilitation of the Nitchequon site is between 3.4 and $5.0 M.

Case Study on the In Situ Destruction of Contaminants at a Dry Cleaner Site

Sunitha Chavali, Reardon Environmental, Inc., 4606 FM 1960 West, Suite 342, Houston, TX 77069, Tel: 281-781-0030, Fax: (281) 537-7204, Email: sunithachavali@yahoo.com
Thomas R. Liebert, P. E., Reardon Environmental, Inc., 4606 FM 1960 West, Suite 342, Houston, TX 77069, Tel: 281-781-0030, Fax: 281-537-7204, Email: trl5402@aol.com

Soil and groundwater contaminated with Perchloroethylene (PCE) poses a challenge for remediation, as PCE is highly resistant to natural degradation due to its high chlorine content and high specific gravity. Hence powerful oxidizing agents are required to break PCE into benign by products. An operating dry cleaning facility in Longview, TX required immediate remediation of the soil and groundwater contaminated by PCE. Due to the high contaminant levels, Reardon injected a combination of two powerful oxidizing agents: Fenton’s reagent with a high oxidant to catalyst ratio to generate superoxide radicals ( ) and remediation grade sodium persulfate to generate sulfate radicals ( ). By generating these powerful oxidizing radicals in soil, Reardon was successful in breaking the chlorinated molecule into chloride ions, steam and carbon dioxide.  Reardon excavated the highly contaminated parts of soil and treated it in separate roll off bins by injecting the above-mentioned oxidants into the soil under high pressure using its patented injection technology. Sodium persulfate and ferrous sulfate (catalyst) under low pressure will be used initially for groundwater treatment. The contaminant concentrations before and after the treatment will be presented.  The challenges faced by Reardon during the remediation of the site like operating problems experienced with the different oxidants and tenant/contractor interface issues, which were solved in the short timeframe for the project and the results will be discussed. The reaction contaminant chemistry in the soil and groundwater will also be discussed in detail.

In-Situ Chemical Oxidation of Petroleum Contamination by Activated Persulfate - Field Study

Scott C. Crawford, Xpert Design and Diagnostics, LLC, 22 Marin Way, Unit 3, Stratham, NH 03801, Tel: 603-778-1100 x234, Fax: 603-778-2121, Email: Crawford@XDD-LLC.com
Kenneth L. Sperry, P.E., Xpert Design and Diagnostics, LLC, 1275 Glenlivet Drive, Suite 100, Allentown, PA 18106, Tel: 484-224-3031, Fax: 484-224-2999, Email: Sperry@XDD-LLC.com

An innovative in-situ oxidation treatment using activated sodium persulfate (the X-Ox Process) was field-tested at a site impacted with petroleum hydrocarbons.  Persulfate (S₂O₈^2-) in the presence of naturally occurring or externally supplemented ferrous iron (Fe²⁺) will react to produce a powerful oxidant known as the sulfate free radical (SO₄^-·).  The X-Ox Process involves the addition of a chelating agent to control the rate of sulfate free radical formation, which can increase the efficiency of the reaction with the target compounds.  The site is a former retail gas station where two gasoline underground storage tanks have impacted soils and groundwater.  Total BTEX concentrations of 11,370 mg/L and total alkylbenzenes concentrations of 5,000 mg/L have been observed.  The geology consists of a fine to coarse-grained sand to a depth of 3.6 meters below surface grade overlying granite bedrock.  During a 3-day injection event, a total of 17,269 liters of 60 g/L persulfate solution was injected into the target area (approximately 1,000 Kg of persulfate) with ferrous iron and a chelating agent.  The oxidant loading was equivalent to 1.7 grams of oxidant per kilogram of soil.  In practice, this is a relatively low oxidant loading.  Initial post-injection groundwater data indicates that total BTEX concentrations have been reduced by 26% to 48% after the single oxidant dose.  Total alkylbenzene concentrations were reduced by up to 91% in one part of the target area, however, there was significant rebound in the remainder of the target area (i.e., between 84% and 98% of the initial concentrations).  Formation of intermediate compounds was also observed, and these intermediate compounds are continuing to degrade with continued contact with the oxidant.  Initial results are promising considering a relatively low oxidant loading was used in the preliminary treatment. 

Expedited Remediation of a Brownfields Site Using the Modified Fenton’s Process

Prasad Kakarla, P.E., Thomas Andrews, P.E. and David Zervas, In-Situ Oxidative Technologies, Inc. (ISOTEC^SM), 51 Everett Drive, Suite A-10, West Windsor, NJ 08550, Tel: 609-275-8500; Email: pkakarla@insituoxidation.com

A Brownfields site in New Jersey is being developed for construction of a new home improvement retail store.  Due to high levels of TCE, PCE, VC, and BTEX contamination present over a 32,000 Sq. ft portion of the site, an expedited remedial schedule was established to substantially reduce soil concentrations, which exceeded 2,800 mg/kg for average volatile organic compounds (VOCs).  The bulk of the contamination is present from 5 to 15 feet below ground surface (bgs) with the hot spots indicating total VOCs of up to 11,200 mg/kg.  Subsurface geology consists of mostly sands with groundwater encountered at depths of 7-8 feet bgs.  In situ chemical oxidation (ISCO) using a modified Fenton’s reagent was selected to achieve the remedial objectives. The modified Fenton’s reagent uses patented chelated iron catalysts and stabilized hydrogen peroxide to promote destruction of contaminants under circum-neutral pH (i.e. pH 5-8) conditions.  An existing groundwater pump-and-treat system remained operational at the site during the course of the treatment program.  It was hoped that source area soil remediation will reduce the operation and maintenance timeframe of the pump-and-treat system from the currently estimated 100 years to less than 20 years.  Therefore, a remedial goal of VOCs less than 5 times the New Jersey Residential Direct Contact (NJRDC) Criteria was set for ISCO.

The currently ongoing modified Fenton’s treatment program was initiated in August 2003 using a plurality of permanent injection wells and temporary direct push injection points. An aggressive, multiphase injection approach is being implemented at this site to allow for enhanced desorption and degradation of recalcitrant contaminants. A total of 32 permanent wells were installed at a spacing of 25 feet from one another. Additionally, the injection activities utilized between 60-90 direct push points per event to destroy soil contamination.  Desorbed free product was recovered periodically using peristaltic pumps to accelerate the cleanup process.  To date, the injection activities have been performed over three (3) 17-18 day events, with two (2) additional events scheduled to be completed by March 2004.  A total of up to 16 sampling locations were utilized for performance data collection.  Results received to date indicate a 78% destruction of total VOCs in site soils and 88% destruction in site groundwater. Of the soil samples collected, eleven of the 16 locations have indicated reduction to below the NJRDC cleanup criteria following three injection events.  Additional results should be available within the next few months in time for the conference.

Naphthalene Removal by Pulsed and Peroxide-Coated Microbubble Ozone Injection

William B. Kerfoot, Kerfoot Technologies, Inc., 766-B Falmouth Road, Mashpee, MA  02649, Tel: 508-539-3002, Fax: 508-539-3566, Email: wbkerfoot@kerfoottech.com
Andrew Brolowski, Streamline Environmental, 68 Hatchville Road, East Falmouth, MA  02536, Tel: 508-274-4228, Fax: 508-539-3566

Naphthalene compounds occur commonly in coal-tar product and weathered heavier oil spills.  The compounds are readily oxidized in aqueous or adsorbed phase by microbubble ozone treatment.  The authors compared the rate of oxidation of naphthalene during aqueous reaction with dissolved ozone, microbubble ozone, and peroxide-coated ozone.  In the Perozone™ system the OH· radical is not transported towards the contaminant; it is continuously generated by the interaction of hydrogen peroxide and ozone injected pulse-wise into saturated soil.  The extent of travel in soil of reactive Perozone™ is compared to microbubble ozone.  The kinetics of naphthalene oxidation is reviewed and compared to observed rates of removal.  Hsu and Masten (1997) raised questions about whether excessive soil oxidative demand (SOD) or self-decomposition would interfere with effective treatment of polyaromatic compounds.  Field experience with pulsed ozone has shown low SOD and rapid treatment of naphthalene under a variety of conditions.

In-Situ Chemical Oxidation (ISCO) Applications at MGP Sites

J. David Mannion, Shaw Environmental, Inc., 88C Elm Street, Hopkinton, MA 01748-1656, Tel: 508-497-6165, Fax: 508-435-9641, Email: David.Mannion@shawgrp.com
Duane K. Root, Ph.D., Shaw Environmental, Inc., 304 Directors Drive, Knoxville, TN 37923, Tel: 865-694-7360, Fax: 865-694-9573, Email: duane.root@shawgrp.com

This paper focuses on two refinements to the application of in-situ chemical oxidants at MGP sites; pulsed ozone technology, and the use of persulfate reagent.  Shaw’s experience with ozone has led to the development of pulsed ozone technology (patent pending) for the treatment of PAH contamination.  Testing with this technique has demonstrated the ability to destroy PAHs using up to an order of magnitude less ozone than traditional continuous application technology. A more recent oxidant alternative to permanganate ion and Fenton’s Reagent is persulfate ion.  Persulfate ion is a stronger oxidant than permanganate, capable of oxidizing PAHs, and at the same time is typically much less sensitive than permanganate to chemical demand from natural organic and other petroleum (TPH) compounds found in MGP soils.  Under these conditions, persulfate reagent may be preferred over Fenton’s reagent for treatment.  There are potential MGP site applications that may be well suited to the use of these reagent technologies.  They include PAH contaminated groundwater and saturated zone soils or potentially shallow soils that can be treated by an infiltration gallery.  Chemical oxidant behavior and characteristics are compared to MGP site characteristics to select which, if any, chemical oxidation technologies are appropriate for consideration at a site.

Strategic Use of In-situ Ozonation to Achieve Expedited Closure

Steven D. Schroeder, P.E., RMT, Inc., Patewood Plaza One, 30 Patewood Drive, Greenville, SC 29615-3535, Tel: 864-281-0030, Fax: 864-281-0288, Email: steve.schroeder@rmtinc.com

Remediation for chlorinated volatile organic compounds (CVOCs) in groundwater often requires several years of time and a continuing influx of funding before meaningful cleanup progress can be achieved.  Companies which fund these efforts have strong financial drivers to quickly reduce environmental liabilities, and are becoming increasingly wary of technologies that commit them to years of cost without a reasonable expectation of when, or if, an endpoint will be reached.  In-situ oxidation provides an alternative that can be used as a key component to a site-wide remedial approach, which significantly reduces lifetime costs and the time required to achieve cleanup targets.  Full-scale site remediation case studies, which use in-situ oxidation with ozone injection, are presented.  One case study, highlighted and presented in detail, consists of a federal CERCLA site in South Carolina, where in-situ ozonation is being used as a supplemental remedy for groundwater.  After several years of air sparging, CVOCs remained present and in-situ ozonation has been applied to complete remedial efforts.  After only eighteen months of treatment, groundwater concentrations in all monitoring points are at or below MCLs, and EPA has granted approval for shutdown of the ozone system.  Cost and performance information is also presented for other full-scale site applications where this approach is being successfully employed.  For these case studies, the strategy to achieve closure relies on in-situ oxidation to reduce high concentrations of CVOCs in groundwater, to the extent required to facilitate natural attenuation as a final polishing step.  As part of implementation,  groundwater recovery systems will be removed from service years ahead of projections or never implemented.

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