George R. Alther, Biomin, Inc.

Organoclays have been used for some 20 years to remove oil, grease, and other chlorinated hydrocarbons of low solubility from water. Organoclays are bentonites which are modified with quaternary amines to render them hydrophobic, or organophilic. This characteristic allows them to remove non-polar organics by means of partition, from water. Slight alteration causes a positive charge on the hydrophobic end of the amine chain. This charge allows removal of negatively charged organics and inorganics from water.

However, bentonites are natural ion exchange resins. The quaternary amines cover, at best, 45% of the surface of each clay platelet. The remaining surface is thus available for ion exchange of heavy metals with the prevailing sodium, calcium and magnesium ions. Laboratory data as well as actual field data will be presented and the viability of organoclay as a dual adsorbent will be discussed.

Ralph S. Baker and John M. Bierschenk, TerraTherm, Inc.

In Situ Thermal Destruction (ISTD) is a soil and sediment remediation process in which heat and vacuum are applied simultaneously to subsurface soils or aboveground soil/sediment piles. Heat flows into the soil primarily by conduction from heaters typically operated at 700-800° C. The heaters are installed in wells at regular intervals within the soil. As soil is heated, organic contaminants in the soil are vaporized or destroyed by several mechanisms, including evaporation, steam distillation, boiling, oxidation, and pyrolysis. The vaporized constituents are drawn toward extraction wells for aboveground treatment. Compared to fluid injection processes, the conductive heating process during ISTD is very uniform in its vertical and horizontal sweep. The combined effectiveness of both heat and vapor flow leaves no area untreated. Laboratory treatability studies and field project experience at seven ISTD sites have confirmed that high temperatures applied over a period of days result in extremely high destruction and removal efficiency of even high boiling point contaminants such as PCBs, pesticides, PAHs and other heavy hydrocarbons. The effectiveness of the process is not limited by the presence of heterogeneous soil conditions or clay. Despite high pre-treatment soil contaminant concentrations, post-treatment soil concentrations have typically been non-detect. Moreover, most of the contaminants (95-99% or more) are destroyed in the soil before reaching the surface. Stack sampling has demonstrated that emissions of toxic air pollutants including dioxins are substantially below standards. ISTD thus offers a cost-effective means to reliably achieve stringent cleanup goals that have not been previously possible by in-place treatment. The implications for the setting of cleanup standards are discussed.

Richard Corbin and Christian Belanger, Biogenie Inc.

This paper will document the successful remediation of a 190-acre former refinery site which had been in operation for some 55 years. Following the dismantling of the refinery and storage installations, 800,000 tons of contaminated soil and sludge, as well as refinery wastes, were excavated and temporarily stockpiled. Biogenie performed in its laboratory facilities a biotreatability study and, on the grounds of its results, proposed a guaranteed (cost-capped/pay-for-performance) remedial solution based on the application on an ex situ biological treatment process to the stockpiled material. Minimizing displacement of the contaminated material was a key feature of the strategy which provided substantial costs savings. From a technical standpoint, customizing the selected biotreatment process was a challenge in itself when considering the type of contaminants and material (heavy hydrocarbons in a clayey soil) as well as the sheer size of the project. This project, which was completed two years ahead of schedule, demonstrates outstanding technical know-how as well as engineering and project management capabilities.

Greg Byeke, P.E., Thermal Remediation Services, Inc. (TRS)

Six-Phase Heating (SPH) has been commercially available for soil and groundwater remediation since 1997. During this time, thirteen commercial projects have been completed including remediation of DNAPLs and LNAPLs. Full-scale cleanups typically require three to 12 months of operations. The U.S. Department of Defense, U.S. Department of Energy, U.S. EPA, state regulatory agencies and the private sector are showing major interest in the technology.

Mr. Beyke has largely been responsible for several engineering and operational improvements to the technology that has resulted in pricing efficiencies and new applications. The following major milestones have been achieved since 1997:

• The world’s first DNAPL remediation resulting in the site being closed,
• The world’s first SPH and multiphase extraction combination for LNAPL removal,
• The world’s first SPH deployment underneath an operating shopping mall, roadway, and in the presence of multiple buried utilities,
• The world’s first SPH deployment underneath a U.S. Air Force F-16 manufacturing facility, and
• The world’s first Methylene Chloride remediation by SPH enhanced hydrolysis.

This presentation will focus on the projects listed above, the engineering and operational improvements made to the technology and the lessons learned during the past fours years deploying SPH.

Mark Krivansky, Northern Division, Naval Facilities Engineering Command, Dan Bryant, Geo-Cleanse International, Inc., Elizabeth Martin and Shannon Gleason, ENSR

A release from a former gasoline UST was identified at Naval Weapons Industrial Research Plant (NWIRP) Bedford. The area was identified as Site 4 and incorporated the Transportation and the Antenna Range Buildings. The UST was removed in December 1988, and subsequent investigations delineated a narrow groundwater plume originating near the former UST. Total BTEX concentration in 6 wells exceeded an interim cleanup objective of 300 ug/L. Maximum and mean total BTEX concentrations were 42,200 ug/L and 18,563 ug/L, respectively. Fenton’s reagent in-situ chemical oxidation (ISCO) was selected to reduce overall source area contaminant mass. Treatment under buildings, underground utilities, the UST grave, low permeability glacial till, and steep hydraulic gradient complicated ISCO design. The UST grave was re-excavated, an additional 35 cubic yards of contaminated soil were removed, and a liner was placed prior to backfilling. A total of 20 injectors and 9 vent wells were installed encompassing the horizontal and vertical dimensions of the source area. A total of 1,600 gallons of 50% hydrogen peroxide solution, plus catalyst, were injected over 5 days in November and December 2000. A round of groundwater samples collected 5 days after treatment indicated maximum and mean total BTEX concentrations of 19,271 and 4,524 ug/L, respectively (average reduction of 76%), with 4 wells exceeding the cleanup objective. A second treatment round in January 2001 included injection of 3,770 gallons of 50% hydrogen peroxide plus catalyst over 10 days. Groundwater samples collected during treatment (after 5 days of injection) indicated further reductions of BTEX, with maximum and mean total BTEX concentration of 8,510 and 2,291 ug/L, respectively (average reduction of 88%). Groundwater samples collected 10 days after conclusion of the January injection indicate only 2 wells remain above the interim cleanup objective, with maximum total BTEX concentration of 1,880 and 1,822 ug/L, respectively.

Gerald L. Kirkpatrick and Kevin W. Frysinger, Environmental Standards, Inc.

Remedial action plans and projects, regardless of size, are now best prepared for and executed if computer visualization tools are incorporated into their structure. Examples of three key roles of using visualization tools in the soils remedial action planning process are examined. Computer visualization tools are currently available that can cost-effectively, accurately, and quickly evaluate the potential applicability of remedial technologies and provide stakeholders an improved understanding of the project such that well informed remedial action plans are developed.

Consideration of soil volume is critical in the remedy selection process. Modern computer visualization tools can render and animate, in a three-dimensional sense, the volume and location of affected soils at a site. This understanding leads to improved decisions regarding the probable efficacy of a given remedial action and provides a common sense assessment of the likelihood that a certain remedial action will achieve an acceptable project outcome. Contractor cost estimates and remedial action equipment requirements are also better forecast when using mathematically simulated three-dimensional visualization models.

During remedial action planning, it is helpful for a contractor to understand what soil is being removed/treated and where the affected soils are located. Three-dimensional visualization provides contractors, who are not necessarily familiar with the site or other aspects of the facility, the opportunity to examine the affected soils from virtually any angle and depth, prior to beginning remedial action; this examination results in an improved understanding of the construction objectives.

Not all remedial actions can be developed such that existing property operations are unaffected. Visualization tools can also be used to minimize remedial action impacts to facility operations that could be affected during the remedial action; the impact on traffic flow, underground piping, overhead wiring, and existing structure integrity must be considered. Visualization tools, including animation, are invaluable in communicating needs and planning for such situations.

Wallace Hise and Ross Sollars, Chung and Associates, Inc., Dean Armstrong, Kleinfelder, Inc

The Defense Depot Ogden (DDHU) is a former Defense Logistics Agency facility in Utah that is restoring contaminated property to facilitate transfer as part of the Base Realignment and Closure (BRAC) process. Groundwater at Operable Unit 4 is contaminated with TCE, DCE and vinyl chloride above the federal MCLs. A groundwater extraction, treatment and re-injection system has been operating at this site for over 5 years with an expected of life of at least 20 additional years.

A 5-year contract for operations, maintenance, engineering support, and optimization was commenced in July 2000. At this time the system was not meeting performance requirements as specified by the Record of Decision. Our first task included an aggressive maintenance regimen to rehabilitate the well field and increase system flow through. We addressed biofouling issues, converted injection wells to extraction wells, and took extraction wells off line in order to maintain plume containment and increase groundwater recovery rates. This resulted in nearly a 20 percent increase in the volume of groundwater recovered and treated. We also performed baseline sampling to determine plume dynamics and the rate of contaminant mass removal.

A thorough engineering evaluation was conducted of the physical plant over the initial 3-month period. We identified several high priority corrective actions requiring immediate attention. These included: replacement of a pipeline to relieve pressures that are near the design capacity (reduce potential liability of pipe rupture and release), return the PLC system to its original design specification (ensure functionality of alarms and signals for after-hours response), and installing a pneumatic control system in an extraction trench (eliminate equipment cycling and ensure a constant drawdown for plume containment).

Edward M. Kellar, Harding ESE, William B. Kerfoot, K-V Associates, Inc., Jeff Gadt, E&E/Start, Andrew Brolowski, K-V Associates, Inc., and Tom Colwell, Harding ESE

A pilot test of the C-Sparge™ process was begun on July 10, 2000, for the purpose of using the system as a reactive wall for containment of a Halogenated Volatile Organic Compound (HVOC) plume impacting a municipal well field in Columbus, Nebraska. The test focused on optimizing the process for interception and destruction of tetrachloroethene (PCE) and trichloroethene (TCE). The spargewell (IWS) and a 6 monitoring well (three-dimensional) array was installed in the upper sand and gravel aquifer to a depth of 65 feet below grade. The formation increased in permeability vertically to a mixture of sand and gravel located above a silty clay layer (aquiclude) 13 to 18 feet thick. Static water was at 16 feet below grade with a groundwater flow to the southeast at about 0.7 ft/day. The 2-inch monitoring well array with 10-foot-long slotted PVC screens consisted of three wells set to the water table, one at mid-depth and one just above the aquiclude. The horizontal distances were staggered outwards from 15 feet to 60 feet from the spargewell (IWS). A bench-scale test was performed on groundwater taken from monitoring well KV-1 to determine removal of PCE and TCE, the principal contaminant HVOCs. A comparison of the reaction run under pressure (0.5 psi) versus vacuum separated the gaseous versus aqueous phase reactions. Analysis of the results were divided into two sections—the findings and projections based upon the 20-day intensive testing and then a comparison of the kinetic projections with observed removal over the remaining two-month period under optimized conditions. All monitoring wells showed distinct changes during the testing period. After initialization, a series of test conditions were performed to determine optimal ozone dosage, base flow volume, and sequencing frequency.

William B. Kerfoot, K-V Associates, Inc., M. Saqib Khan, Kansas Department of Health and Environment

The following report describes a pilot test and results of remedial efforts of the C-Sparge™ process for removal of dissolved chlorinated solvents from groundwater. The pilot test was conducted by Burns and McDonnell Waste Consultants, Inc. (BMWCI) with K-V Associates, Inc. (KVA) for the Kansas Department of Health and Environment (KDHE) at the Kansas State Fairgrounds in Hutchinson, Kansas, for a three-month period from June 10, 1997, through August 28, 1997. The pilot test involved installation of two side-by-side C-Sparge™ wells and one set of three and one set of five 2-inch ID monitoring wells, staggered with both distance and depth. One sub-site (K) was set up to test the C-Sparge™ process, and the other, the Microsparge™ process, which does not employ ozone (sub-site B). Detailed observations were made for the first ten days using both gas chromatographs (GC’s) fitted with PID (KVA-supplied), and IC (KDHE mobile van) detectors. The relative effectiveness of the technology was evaluated with other systems with respect to contaminant removal, overall cost, ease of operation, and applicability to various locations. Contaminant removal effectiveness of each treatment system was assessed primarily by observing the reduction in dissolved-phase PCE concentrations over time. Cost-effectiveness of each system was determined by evaluating capital hardware and installation costs, ongoing operation costs and labor requirements to operate, maintain, and optimize each system. Following this, systems were installed at Garden City and Hutchinson, Kansas, in 1998 for remedial action. Upgrading of the Garden City unit was performed in 1999. In June, 2000, concentrations of PCE downgradient of the treatment region were at 4.8 ppb, less than 5 ppb drinking water standards. Upgrading of the Hutchinson site is underway at present.

Irshad Hussain, Qaisar M. Khan and Zafar M. Khalid, National Institute for Biotechnology & Genetic Engineering, Pakistan

Adsorption of dyes from aqueous effluents by economical and commercially available adsorbents seems to be a suitable remediation technology for the treatment of high flow effluents with low concentration of pollutants. In this study maximum adsorption capacity of dried biomass of Azolla pinnata, mustard seed cake and sesam seed cake was evaluated for rhodamine-B and congo red which was found to be 48, 15 and 6 mg/g for rhodamine-B and 20, 10 and 8 mg/g for congo red respectively. Effect of pH, time, adsorbent dosage and initial chromium concentration was evaluated and further study was performed at optimum conditions. Adsorption data was analysed by Langmuir and Freundlich adsorption isotherms. Both of these adsorption isotherms agreed quite well with the adsorption data thus indicating a complex adsorption mechanism. All the loaded adsorbents were successfully desorbed and regenerated with 0.5N NaOH and 0.5N H₂SO₄ respectively with a recovery of more than 70%.

Of these dried biomass of Azolla pinnata seems to have a great potential to adsorb rhodamine-B & congo red and an important candidate for the treatment of industrial effluents contaminated with these dyes due to its easy availability, economical price (~ $ 2/Kg ), exceptionally higher adsorption capacity and ability to be easily desorbed and regenerated for recycling. Column study (2 cm bore size, flow rate 1 ml/min., pH-2 for rhodamine-B while original pH of congo red solution) for the removal of these dyes by dried biomass of Azolla pinnata did reduced their adsorption capacities for three cycles thus proving its importance to be used in the treatment of industrial effluents contaminated with dyes.

Daniel K. Mason, Tighe & Bond, Inc.

On May 5, 2000, a faulty valve on an above ground storage tank (AST) caused a release approximately 55 gallons of No. 2 fuel in the basement of a house in western Massachusetts. Oil migrated along the basement floor and into a crack between the floor and the basement wall. Soil at the site consists of well-sorted, medium grained sand. The fuel oil migrated beneath the basement floor, the foundation wall and a small section of the exterior soils. An investigation was conducted in accordance with the Massachusetts Contingency Plan (MCP) to remove the contaminated concrete from the basement floor, and a small amount of the impacted soil. However, this cleaning was unable to sufficiently remediate the release. The residual contamination was delineated a hand auger, a Rhino air hammer and drill rig. During delineation, groundwater was not encountered to a depth of at least 23 feet. After delineation, two remediation alternatives were evaluated: excavation of soils and Peroxide Oxidation. At half the cost, the use of peroxide was determined to be the most cost effective to the client and the least disruptive to the homeowner. A system for the delivery was designed and of a total of 605 gallons of 35% Hydrogen Peroxide solution was applied to contaminated soils. After these applications, sampling was conducted throughout the release area using a unique sampling system devised for this site. Using averaging methods, soils were, on average, below MCP residential cleanup standards.

This paper will document the challenges posed in the sampling and remediation of the release. Among the questions that had to be answered were (1) What is the best method to delineate the release? (2) What is the best remediation method at a site with a known contaminant, well-sorted sandy soils, and contamination beneath the foundation of a residence? (3) How many rounds of sampling must be conducted? And finally, (4) What is the point at which soils can be considered clean?

Peter W. Sawchuck, P.E., Key Environmental, Inc., Shannon Craig, Beazer East, Inc., Murielle Ting, Key Environmental, Inc. and James S. Zubrow, P.G., Key Environmental, Inc.

Two years of groundwater monitoring data demonstrate that groundwater remedial objectives have been accomplished at a former coke and by-products facility through the integrated use of barrier wall and surface cover systems, and natural attenuation. The barrier wall system is comprised of a 3-sided, 4,500 foot long slurry wall bordering the river and enclosing the former process areas. The surface cover is processed dredge material which consists of sediments from the New York/New Jersey area waterways stabilized with Portland cement. No active pumping is required to achieve the containment. Physical data validate that groundwater flow has been controlled and redirected away from the river and seepage velocities have been reduced. Groundwater chemistry data show that the dissolved plume has been controlled, not expanded and biodegradation is occurring. Inspections along the river indicate that discharges of DNAPL have been mitigated.

Michael G. McDonald, McDonald Morrissey Associates, Inc., Dr. Calvin Chien, E.I.duPont de Nemours and Company, Dan Morrissey, McDonald Morrissey Associates, Inc., and Charles Spalding, McDonald Morrissey Associates, Inc.

From time immemorial wells have been vertical shafts into which water has flowed horizontally. Although the purpose of wells is, generally, to provide a source of water for domestic consumption, crop irrigation and a variety of other uses, wells are also used to remove contaminated water or control its migration. It has been observed that the traditional vertical well orientation requires the pumping of a lot of uncontaminated water in order to remove the contaminated water.

It has been hypothesized that horizontal wells may permit smaller amounts of water to be pumped for a given amount of solute removed. Thus, processing the water would be less expensive. Furthermore, a single horizontal well may replace many vertical wells thereby saving well construction costs. In the last few years the technology to construct horizontal wells has been perfected and horizontal wells have been increasingly used to remediate contaminated areas.

To facilitate the assessment of the effect of horizontal wells on ground-water systems, an addition to the widely used ground-water flow model, MODFLOW (McDonald and Harbaugh 1988), has been developed. The theory, design, and use of this addition are presented.

Richard Tobia, PE, Christopher Voci, MA, and John Sturman, PE, RG. LFR Levine Fricke

This study evaluated the efficacy of remediation of light nonaqueous phase liquid (LNAPL) through addition of oxygen release compound (ORC_TM). Groundwater at the site was impacted by a release of No. 2 fuel oil. A layer of LNAPL persisted on the groundwater after an underground fuel tank along with contaminated soil was removed. Through a combination of LNAPL recovery and passive natural attenuation, LNAPL was reduced to a thin layer or sheen. The relatively low hydraulic conductivity of the water-bearing materials in conjunction with the small volume of LNAPL present led the authors to select ORC as a remedial alternative. ORC is not designed for or typically used where LNAPL is present. The reduction of dissolved-phase hydrocarbons through oxygen-enhanced natural attenuation alters the equilibrium, allowing LNAPL to solubilize and become subject to the natural attenuation process. Chemical and geochemical indicators were closely watched to evaluate the attenuation process.

A. Tetior, Prof., Dr. Sc., Moscow State University of Environmental Engineering

Any engineering constructions in a coastal zone contacting to water: (buna, coast-protecting walls, berths, piers, artificial reeves and algae, device for cultivation of seafood) must strengthen a coast, retain beaches, shape detritus at the bottom, quenched energy of waves and simultaneously framed requirements for fastening of biofouling to substratum, cultivation of sea organisms, including living in a coastal zone, and clearing of water. Ecological coast-protecting structures can be self-growing; the calcareous stone is increased from salts, contained in water, of water on thin reinforcement bar. It is possible also to make these structures as actively - biopositive, when series of functions amplify at the expense of entering energy from renewable energy sources (waves, sun, wind). It is necessary to create shelters for animal, and indestructible by waves sites of substratum for an attachment of plants and animate organisms – biofoulings. Ecological coast-protecting structures should maintain the biotope of coastal organisms and plants (stones, desolate by waves, clefts between boulders, rough surface of rocks) or create the artificial biotope. It can be achieved by making of vacuities by a filled stone and freely washed by water and accessible to sea organisms, rough outside surfaces, etc.

Stephen Warren, Parsons Engineering Science, Inc., James Bodamer, FMC Corporation, and Jim Butner, Parsons Engineering Science, Inc.

Remediation activities to remove, decontaminate using ex-situ thermal desorption, and replace approximately 5000 tons of pesticide impacted soil were conducted in June, July and August of 2000 at the FMC Corporation facility in Tampa, Florida. From the design approval stages with regulatory agencies, through the competitive bidding process and remedial implementation, numerous issues were addressed and brought to solution in ways that would cost effectively achieve the desired cleanup goals.

The goal of cleanup was supplemented with a well thought out, two part design structure which had economical remediation as its primary target. Part one involved approval of the remediation approach with the regulators. Among the many issues to be addressed were the following:

• Selection of Thermal Desorption as the remedial alternative
• Siting and public acceptance
• Application of quality control procedures to support compliance
• Site sampling and characterization

Part two of the project structure involved limiting potential cost liabilities through implementation methods such as:

• Use of pre-approved excavation limits to eliminate swelling excavation quantities
• Use of the Interstate Technology & Regulatory Cooperation Guidance document for Low Temperature Thermal Desorption to reduce the cost of Demonstration Testing on the Thermal Desorber.
• Use of bid specifications that clearly eliminated periods of unknown down time due to regulatory approval.
• Use of fast track site preparation prior to the arrival of the thermal treatment contractor to allow for efficient mobilization and assembly of treatment equipment.

The end result of the good planning was a total time of less than eight weeks from beginning of mobilization to completion of demobilization of the Thermal Desorber and cost savings that are estimated at hundreds of thousands of dollars.

Clay minerals such as montmorillonite have a large surface area (700 m²/g). However, in their natural state they are ineffective sorbents for non-ionic organic contaminants because they are hydrophilic and organophobic. Replacing the native cations (Na⁺, Ca²⁺) on clay surfaces with organic cations, via ion-exchange reactions, may change the clay surfaces from hydrophilic to hydrophobic and organophilic, thus making them suitable for adsorbing organic contaminants. Besides modifying hydrophobicity of clay surfaces, the intercalated organic cations also act as "galleries" propping apart the silicate layers within individual clay crystallites, thus exposing an extensive interlayer area for the sorption of extraneous organic contaminants. Since the sorption capacity and other surface properties of the resultant hydrophobic clays are dependent on the nature of the clay mineral and organic cation used, hydrophobic clays can be tailor-made to meet specific technological and user requirements. Potential applications of hydrophobic clays include pollution prevention at source, remediation of contaminated soils and water, amelioration of the adverse impacts of pollution incidents (e.g., oil spills), lining of landfills, and containment of leakage from underground oil tanks/pipes. The relationship between the surface properties of hydrophobic clays and the size, shape, and charge of organic cation may be assessed by chemical and surface analytical techniques, including elemental analysis, X-ray diffractometry, X-ray photoelectron spectroscopy, and solid-state nuclear magnetic resonance spectroscopy.

Zhijian Zhang, TRC Environmental Corporation

Background

Historical fire-training activities at a federal facility site in the 1970's and early 1980's caused soil and ground water contamination. VOCs and chlorinated VOCs plume was fully delineated by performing several phases of field investigations which consisted of drilling 22 soil borings, sampling 40 Geoprobe locations and installing and sampling 13 monitoring wells. Based on the remedial investigation (RI) results, design of an active soil and ground water remedial system was determined in the record of decision (ROD).

Integrated Modeling

A conceptual model, using RI results, describes that the primary soil and ground water contamination was limited in a perched water table aquifer that is detached from the true water table aquifer. The water source for the studied aquifer is surface infiltration from the precipitation.

USEPA HELP model was utilized to determine the total water budget, direct surface infiltration and infiltration from up-gradient surface runoff.

The proposed active soil and ground water remedial system was simulated using a USGS model, MODFLOW. The model was calibrated using both historical water level measurements and pumping test data. To enhance the soil and ground water cleanup, the final designed remedial system includes a 3-well pumping-treat network and a seasonal-operated sprinkler system. This remedial system is currently under construction.