Dispersion v. Biodegradation Processes: Tools to Assist in the Evaluation of Natural Attenuation in Groundwater Systems
Joseph E. Odencrantz, Tri-S Environmental
Richard A. Vogl, HydroGeo Consultants
Anthony Silva, Brownfield Redevelopment Group Co.

Optimization of Ex-Situ Groundwater Treatment System and Long-Term Monitoring Activities at Allegany Ballistics Laboratory (ABL)
Dominic O'Connor, MSCE, PE, LANTNAVFACENGCOM
Steven Glennie, MS GEO, CH2M HILL

Multi-Site, Single-Task Approach to Managing Multiple Remediation Sites
Laura A. Kelmar and Rita M. Bauer, The RETEC Group, Inc.

Biotreatability Study as an Operational Optimizing Tool for the Treatment of PCP and Creosote-Contaminated Soil on a Former Wood Treatment Superfund Site
Nicolas Moreau, Biogenie Corporation
Michel Pouliot, Biogenie Corporation

Full-Scale ISTD Treatment at Former Alhambra, California Wood Treatment Site
John M. Bierschenk, Ralph S. Baker, Robert J. Bukowski, TerraTherm, Inc.
Jenny King, Southern California Edison Company
Tony Landler, Southern California Edison Company

Hydraulic Containment Using Horizontal Wells

Christopher J. Mattair, P.G., Gannett Fleming, Inc., Suite 150, 7751 Belfort Parkway, Jacksonville, Florida 32256, Tel: 904-332-9400, Fax: 904-332-9337, Email: cmattair@gfnet.com
Steven D. Buser, Gannett Fleming, Inc., Suite 150, 7751 Belfort Parkway, Jacksonville, Florida 32256 Tel: 904-332-9400, Fax: 904-332-9337, Email: sbuser@gfnet.com
W. Patrick Harrison, CSX Transportation, Inc., P.O. Box 1288, Social Circle, Georgia 30025, Tel: 404-350-5355, Fax: 904-245-2223, Email: pat_harrison@csx.com

Although introduced to environmental remediation in the late 1980’s, directionally bored horizontal groundwater withdrawal wells are not widely used.  Three considerations have contributed to their slow acceptance: cost, difficulties predicting hydraulic performance, and a negative perception of the “pump-and-treat” approach.  Considerable progress has been made toward resolving the first two considerations.  Knowledge from the oil industry, lessons learned from remediation case studies, and recent research are now available to assist in predicting the yield and capture of a horizontal well.  The capital cost for a horizontal well, which includes the directional boring contractor, materials, development, and waste management, will vary based on site-specific conditions and well specifications.  For instance, foregoing a filter pack will lower the total cost of a horizontal well even though this design choice may require more aggressive well development.  Given that hydraulic containment by “pump-and-treat” can be the best compromise between owners, regulators, and the public, a horizontal well may be the most cost effective choice.  A case study is presented to illustrate the process of selecting, designing, and implementing a horizontal groundwater withdrawal well system.  The site is an active rail classification and maintenance yard located in the Coastal Plain Province of the Southeast U.S.A.  The yard is regulated as a closed hazardous waste disposal facility and, along with 1,711 other facilities subject to the EPA’s RCRA Cleanup Reforms, is facing accelerated demands to implement remedial action to meet a set of ambitious national cleanup goals.  Over 80 acres of site groundwater contain chlorinated solvent constituents, including trichloroethylene at concentrations as high as 630,000 micrograms per liter.  A horizontal well hydraulic barrier has cost effectively eliminated off-site migration and discharge into a 3,000-foot reach of surface water, bringing this site into compliance with the EPA’s goals.

Dispersion v. Biodegradation Processes: Tools to Assist in the Evaluation of Natural Attenuation in Groundwater Systems

Joseph E. Odencrantz, Ph.D., P.E., Tri-S Environmental, Water and Land Offices, 3151 Airway Avenue, Bldg. H1, Costa Mesa, CA 92626, Tel: 714-966-8490, Fax: 714-966-5222, Email: jodencrantz@tri-s.com
Richard A. Vogl, R.G., CHG, HydroGeo Consultants, Water and Land Offices, 3151 Airway Avenue, Bldg. H1, Costa Mesa, California 92626, Tel: 714-966-5333, Fax: 714-966-5222 Email: rvogl@geohydrologic.com
Anthony Silva, R.G., Brownfield Redevelopment Group Co., Water and Land Offices, 3151 Airway Avenue, Bldg. H1, Costa Mesa, CA 92626, Tel: 714-966-9020, Fax: 714-966-5222, Email: anthonysilva2@sbcglobal.net

The term "Natural Attenuation" (NA) has been defined as naturally-occurring processes in soil and groundwater environments that act without human intervention to reduce the mass, toxicity, mobility, volume, or concentration of contaminants in those media. Monitored natural attenuation (MNA) protocols generally involve the collection of biogeochemical data from groundwater monitoring wells at sites. To implement this approach, the data are typically correlated in time and space with the various chemicals of concern (COC’s) to establish predominant biodegradation mechanisms. Unfortunately, some use the first-order decay expression/rate coefficient as a calibration parameter and adjust it until the transport model results match field data.  With this approach, uncertainties with a number of parameters (e.g., dispersion, sorption, biodegradation, etc.) are lumped together in a single calibration parameter. The natural attenuation decay rate estimated using the lumped parameter approach does not distinguish the biodegradation rate/processes from others. We have applied several groups of dimensionless parameters to aid in the interpretation and isolation of reactive and non-reactive transport processes. A series of nomographs have been developed for analysts to easily identify the governing processes in time in the near- and far-field areas from an organic chemical release. Used in conjunction with analytical and numerical models, the dimensionless framework will aid in the interpretation of data and selection of various advanced modeling approaches. The Site-Specific Damkohler Number is a simple check on the rate of mass flux to the biodegradation rate that can be used to estimate the relative importance of plume migration via dispersion.

The developed nomographs were applied to petroleum affected groundwater sites in California and the results of their application throughout the period of record will be presented. Further, the utilization of the dimensionless framework will be applied to a site investigation to demonstrate their vitality for maximum data impact and site analysis.

Optimization of Ex-Situ Groundwater Treatment System and Long-Term Monitoring Activities at Allegany Ballistics Laboratory (ABL)

Dominic O'Connor, MSCE, PE, LANTNAVFACENGCOM, 1510 Gilbert Street, Building N26, Norfolk, VA 23511-2699, Tel: 757-322-4795, Fax: 757-322-4805, Email: oconnordt@efdlant.navfac.navy.mil
Steven Glennie, MS GEO, CH2M HILL, 13921 Park Center Road, Suite 600, Herndon, VA 20171, Tel: 703-471-1441, Fax: 703-471-1508, Email: sglennie@ch2m.com

Optimization of the ABL groundwater treatment plant has resulted in reduced plant downtime and lower operating costs. In order to prevent off-site migration, VOC contaminated groundwater is being extracted from the alluvial and bedrock aquifers and processed by an on-site treatment system.  Treatment and associated long-term monitoring is expected to continue for many years because source removal is impractical.

This groundwater treatment began in 1998 using the following processes;  VOC destruction and dissolved metals oxidation with a UV Peroxide Injection Unit, , metal precipitates and suspended solids removal with a 10 micron filter, residual VOC air stripping, and final carbon adsorption to remove residual hydrogen peroxide.  After several months of operation calcium carbonate precipitation in the carbon filter resulted in a series of plant shutdowns.  pH rise in the air stripper facilitated this precipitation.  An optimization study was performed including a review of influent, effluent, and process water chemistry, after which the UV/peroxide and carbon adsorption units were both eliminated from the treatment process.  Successful operation continued in this manner until scale in the air stripper decreased air flow and hence, the VOC removal rate.  An acid recalculation system was installed to periodically remove this precipitate. The treatment plant continues compliance with air and water discharge standards.  Annual cost savings due to the system reconfiguration are approximately $74,000.

Optimization activities have also been effective in significantly reducing costs associated with long-term groundwater monitoring.  By examining the goals of the long-term monitoring program and working collaboratively with regulatory agencies the frequency of monitoring has been decreased, required analytical parameters have been minimized, and passive diffusion bag samplers have been utilized for sample collection.  These efforts have resulted in annual cost savings of approximately $366,000.

The presentation will provide site/plume maps, treatment plant drawings, sampling plans, and cost charts to identify improvements.

Multi-Site, Single-Task Approach to Managing Multiple Remediation Sites

Laura A. Kelmar and Rita M. Bauer, The RETEC Group, Inc., 300 Baker Ave., Suite 302, Concord, MA 01720, Tel:   978-371-1422, Fax:  978-371-1448

The long-term operation, maintenance, and monitoring activities for hazardous waste cleanup sites are often the largest cost factor in the overall cost of a site remedy, due to the long “tail” of site activities potentially involved in site operations. This case study details the activities conducted to minimize costs and decrease the operations and maintenance period for a program of forty remediation sites nation-wide. In addition to cost savings generated by consolidating most of the administrative functions across the forty locations, another significant source of cost reduction came from centralizing similar monitoring and reporting functions across the sites. This means that one person coordinates all reporting functions, all sampling activities were coordinated by one person, all data for the program is evaluated by one person and so on. We call this approach the multi-site, single task management approach.  Using this approach, we were able to reduce the analytical and database maintenance costs by over 50 percent during the first year. We developed a Lotus Notes-based calendar for tracking all monitoring, inspection, and reporting requirements for all of sites. Significant regulatory documents including RCRA, NPDES and POTW permits, Records of Decision, and Remedial Design/Remedial Implementation documents, have been scanned into this program for immediate access by the project team. This program is accessible via the Web to the client for tracking all deliverables and sampling activities. This case study details the program developed to streamline the entire program.

Biotreatability Study as an Operational Optimizing Tool for the Treatment of PCP and Creosote-Contaminated Soil on a Former Wood Treatment Superfund Site

Nicolas Moreau, B.Sc., Biogenie Corporation, P.O. Box 354, Spring Mount, PA  19478, Tel: 215-272-2368, Email: nmoreau@biogenie-env.com
Michel Pouliot, B.Sc., Biogenie Corporation, P.O. Box 354, Spring Mount, PA  19478, Tel: 215-272-2368, Email: mpouliot@biogenie-env.com

The MacGillis and Gibbs Superfund site, located in Minnesota, hosted two former wood treatment facilities that used pentachlorophenol (PCP), a listed hazardous waste, and creosote as a wood preservative that over time impacted a total of nearly 15,000 yd³ of soil.

Based on the soil’s initial PCP level, an average reduction of 90% was required to achieve the restrictive clean up criterion of 10 mg/kg, for 10,500 yd³ of treated soil to be used as backfill on site. As biological treatment was the selected remedy to treat the contaminants of concern, Biogenie undertook, only 4 weeks prior to the full-scale project, a bench-scale biotreatability study to determine the optimal biotreatment parameters for its proprietary ex situ Biopile.  However, due to the limited time available, an insufficient amount of data was collected before the on-site remedial work began. Therefore, non-optimal conditions were initially implemented in the Biopiles which resulted in very limited PCP biodegradation during the first weeks of treatment. Meanwhile, the biotreatability study revealed the presence of a lag phase of approximately 6 weeks before PCP biodegradation began. Additional bench-scale tests were therefore performed in order to determine corrective measures. The influence of the type of amendments utilized, as well as the soil’s pH, humidity and temperature on the indigenous microorganisms’ metabolic activities were closely evaluated. It was found that under specific conditions, PCP biodegradation rates of up to 95% could be achieved in 29 weeks, without the presence of the lag phase observed on the site. The information collected from the biotreatability study allowed for appropriate decisions to be taken and optimal corrective measures to be implemented. Upon completion of the treatment, average PCP biodegradation rates ranged from 93% to 97%, these results being closely correlated with those obtained with the bench-scale study.

With this study, we demonstrate how biotreatability studies may support on-site remediation activities not only by determining optimal biotreatment conditions, but also by finding ways to adjust unfavorable conditions that may occur during full-scale remedial work.

Full-Scale ISTD Treatment at Former Alhambra, California Wood Treatment Site

John M. Bierschenk, P.G., Ralph S. Baker, Ph.D., Robert J. Bukowski, P.E., TerraTherm, Inc., 356 Broad St., Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727
Jenny King, Project Manager, Southern California Edison Company, 2244 Walnut Grove Avenue, Rosemead, CA  91770, Tel: 626-302-4257, Fax: 626-302-9730
Tony Landler, Project Engineer, Southern California Edison Company, 2244 Walnut Grove Avenue, Rosemead, CA  91770, Tel: 626-302-8692, Fax: 626-302-9730

At a wood treatment facility for utility poles that SCE operated from 1921 to 1957, subsurface soils are contaminated primarily with polyaromatic hydrocarbons (PAHs), dioxins and furans.  Approx. 11,500 m³ (15,000 cubic yards) of predominantly silty soil requires treatment, to an average depth of 6 m (20 ft) and a maximum depth of 30 m (100 ft).  The CA Department of Toxic Substances Control (DTSC) established soil treatment standards of 0.065 mg/kg benzo(a)pyrene Toxic Equivalents (TEQ) and 1.0 mg/kg dioxin, expressed as 2,3,7,8-tetrachlorodibenzodioxin TEQ.  A feasibility study led to the selection of TerraTherm’s patented In-Situ Thermal Destruction (ISTD) technology, which utilizes simultaneous application of thermal conduction heating and vacuum to treat contaminated soil without excavation.  The applied heat volatilizes organic contaminants within the soil, enabling them to be carried in the vapor stream toward heater-vacuum wells.  Because vapors are drawn through superheated (600-700°C) soil in proximity to the heater-vacuum wells, most of the contaminant mass present in the subsurface is destroyed in situ, as evidenced by 7 completed ISTD projects.  Contaminants not destroyed in situ are removed with the vapor stream and treated in an Air Quality Control (AQC) system. 

TerraTherm installed 785 thermal wells, including 654 heater-only and 131 heater-vacuum wells, in a hexagonal pattern at 7.0-foot spacing.  TerraTherm is carrying out the heating in two phases, the first phase of which began March 2003.  Each phase will last approximately 90 days, at which time inter-well temperatures will achieve 325°C (620°F).  Subsurface monitoring tracks the progress of heating.  The AQC system includes a regenerative thermal oxidizer with demonstrated capability of achieving 99% DRE; heat exchanger; and granular activated carbon.  A process blower maintains the entire system under vacuum, while a continuous emission monitoring system measures stack emissions.  In accordance with DTSC requirements, TerraTherm is also conducting several rounds of source testing. 

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