Integrated Remediation Technology
Provides Rapid Site Remediation B. H. Bosshard and James Keegan, Newport Beach, CA

An innovative process is being applied to the remediation of both groundwater and soil simultaneously. This technology combines Vacuum Extraction, groundwater recovery, Air-Sparging and enhanced Bioremediation for effective site remediation. Dual Vacuum Extraction process of simultaneous water and soil remediation, developed by Terra Vac, is an in-situ process which recovers liquid, vaporous, dissolved and adsorbed contaminants from the subsurface while enhancing the biodegradation of contaminants in the subsurface. In certain cases, air-sparging can be combined with the Dual Vacuum Extraction process to reduce remediation time frames.

Dual Vacuum Extraction process has successfully been utilized at a number of sites contaminated with Volatile Organic Compounds. One of these sites presented low soil permeabilities (hydraulic conductivity of 10E-8 cm/s), which can limit traditional recovery and bioremediation methods. The Dual Vacuum Extraction process has been successful in remediating such sites with increased recovery rates, increased radius of influence and decreased remediation times. High hydraulic conducivities indicate that air-sparging combined with the Dual Vacuum Extraction process can be the preferred choice. Selected case studies will show when each technology is preferred.

Three case studies will be presented demonstrating the effectiveness of the Dual Vacuum Extraction process and the SpargeVACSM process of air injection enhanced vacuum extraction. The results presented will show:

  • Enhanced bioactivity with the use of the Dual Vacuum Extraction and SpargeVACSM processes.
  • Recovery of VOCs above and below the static water level.
  • Increased recovery rates of VOCs compared to conventional remediation techniques.
  • When is air sparging (SpargeVACSM), with its significantly reduced groundwater treatment costs, the right choice?

Combining these key technologies results in shorter remediation time frames, the capability to achieve lower cleanup goals at significant cost savings.

The case studies will highlight key technical problems in reducing impacted soil concentrations to less than 100 ppm TPH gasoline (at and below the static water table) through the Dual Vacuum Extraction and SpargeVACSM processes and continued reduction of non-volatile components to less than 10 ppm TPH gasoline by bioremediation. The case studies will show a reduction of groundwater impaction from free product to non detectable levels.

Soils Classification Approach For
Effective In-Situ Vapor Extraction Remediation

Bretton E. Trowbridge, P.E. and Juan A. Guerrero, Newport Beach, CA

Classification of soils in the environmental industry is routinely accomplished using the Unified Soils Classification System (USCS). Utilization of this system in the remediation of soils with vapor extraction has lead to a reassessment of its applicability to in-situ remediation evaluations. The USCS has been inadequate in resolving the soil characteristics necessary for optimum design of in-situ vapor extraction systems.

The accurate classification of soils and their properties is the single most important criteria in the choice or design of a remediation system. Proper descriptions and classification of soil types are essential in determining if vapor extraction technology is applicable at a given site. Design criteria such as well spacing and density, well locations and completion details are impacted by soil types. We propose the use of a permeability-based soils classification system which addresses parameters critical to the movement of vapors and liquids though the subsoils as a subsurface vacuum is propagated.

Integrated Pneumatic Soil Fracturing System/Vacuum
Extraction For Remediation of Low Permeability Soils

Anton L. Plaines, Tampa, FL; Robert J. Piniewski, Temperance, MI; and Galen D. Yarbrough, Carrollton, TX

The limitations of vacuum extraction to remediate low permeability soils are related to the diffusion-controlled mass transfer of contaminants and the ability to create advective air flow paths through the subsurface. Typically, higher vacuums are applied to the subsurface during low permeability vacuum extraction projects.

At some sites the application of high vacuums will create advective subsurface flows, and result in a successful remediation. This technique exhibits limitations at sites with very low permeabilities and high water saturation.

At some low permeability sites where contamination has spread from repeated creation of desiccation fractures over many years, subsurface flows during vacuum extraction will preferentially occur in active desiccation fractures. This may result in a diffusion-controlled mass transfer regime and an ineffective or slow soil clean-up. Diffusion-controlled mass transfer can be orders of magnitude slower than advective-controlled mass transfer.

Pneumatic soil fracturing, similar to techniques used for years in the oil industry, has been adopted to successfully increase contaminant extraction rates in low permeability soil vacuum extraction projects.

In this process, high pressure air is injected into the soils, causing micro-fractures and creating additional subsurface flow paths. Pneumatic soil fracturing enhances advective-controlled mass transfer, and results in a faster soil remediation.

Case studies are presented for pilot studies conducted in New York and Louisiana. The results indicate that an integrated pneumatic soil fracturing/vacuum extraction system will increase the extraction rate of contaminants from the subsurface and increase the volume of soil influenced by the vacuum extraction wells, resulting in a reduced time frame for site remediation.

Thus, by implementing a more effective soil remediation in a shorter time frame, a reduction in overall project costs may be realized.

In-situ Bioremediation in Low Permeability Silt and Clay Soils

By Bretton E. Trowbridge and James Keegan, Newport Beach, CA

Conventional wisdom in technical circles within the environmental industry is that Bioremediation, and especially In-Situ Bioremediation, is not technically or economically feasible in low permeability soils. The authors are involved in a remediation program that involves the integration of several technologies that make the In-Situ Bioremediation of contaminants in low permeability soils successful.

The low permeability soils at an industrial site have been reported as silty clays and clays with a high moisture content and hydraulic conductivities in the range of 10E-6 to 10E-8 cm/s. The clays are classified as high plasticity CH clays and described as up to 70% clay and 30% silt. The soils are contaminated with Methyl Ethyl Ketone (MEK), Dichloroethane (DCA), Methylene Chloride (MC), 1,1,1-Trichloroethane (TCA), Benzene, Toluene and Xylene.

The authors combined Vapor Extraction, High Vacuum Vapor Extraction (greater than 15" Hg), Pneumatic Soil Fracturing and Bioventing technologies to successfully remediate the low permeability soils. In this application, high vacuum vapor extraction and pneumatic soil fracturing to these low permeability soils creates new flow paths for the extracted and injected air and decreases the diffusion path length for contaminant-impacted areas distal to these flow paths. As a result of these pneumatic operations, fresh air drawn and injected into the subsurface soils will stimulate the indigenous microorganisms and promote natural biodegradation.

The predominant chemical in the site soils is MEK, which is particularly susceptible to biodegradation. The indigenous microorganisms in the site soils are also capable of utilizing MEK as an energy source for the co-metabolism of the other chlorinated hydrocarbon contaminants.

Initial analyses of the soil indicate that the soil contains total heterotrophic counts on the order of 2 x 10E5 CFU/g, MEK degrader counts on the order of 1 x 10E5 CFU/g and low nutrient levels. The progress of biodegradation will be tracked using extraction system data, in-situ respirometry tests, interim soil sample analyses and other system data. Based on operational data, nutrient additions will be injected through the pneumatic soil fracturing system.

Soil Remediation and Free Product Removal Using
In-Situ Vacuum Extraction with Catalytic Oxidation

Bretton E. Trowbridge, P.E., Newport Beach, CA; James J. Malot, P.E., San Juan, PR

Vacuum Extraction is an effective tool for the in-situ removal of liquid, residual, and vapor phase volatile hydrocarbons from subsurface soils and liquid phase volatile hydrocarbons floating on the groundwater. Numerous papers have been presented on Vacuum Extraction for the removal of hydrocarbons in subsurface soils.

This paper presents three case studies of full-scale Vacuum Extraction remediation projects for the removal of hydrocarbons from the subsurface soils and the simultaneous removal of liquid hydrocarbon floating on the water table. The focus of the case study is the removal of the liquid hydrocarbon floating on the water table.

The process of Vacuum Extraction involves the induction of air flow through soils by the application of a vacuum within the soil matrix. The induction of air flow is typically accomplished with an extraction system connected to vertical or horizontal extraction wells. As the air flows through the soil void space, liquid hydrocarbon is volatilized and the hydrocarbon vapors are purged from the soils into the well. The extracted vapors are typically fed into a vapor treatment unit.

The three case studies include a previous petroleum products terminal, a residential subdivision and a former solvent handling facility (Superfund site). All three sites utilized a catalytic oxidizer for the treatment of the extracted vapors.

The petroleum products terminal and the subdivision involved the removal and treatment of hydrocarbons within the gasoline boiling range. The Superfund Site involved the removal and treatment of a mix of aliphatic, aromatic and chlorinated hydrocarbons.

Advances in the Vacuum Extraction Technology
for Effective Subsurface Remediation

Joseph A. Pezzullo, P.E., Langhorne, PA

The Vacuum Extraction technology has become one of the most widely acclaimed methods for remediating soils contaminated by petroleum hydrocarbons and volatile organic compounds (VOCs). The removal of the source of contamination in the soil is often the first step in the effective control of groundwater contamination.

Though originally thought effective only for vadose zone contamination by light end hydrocarbons in higher range permeable soils, Vacuum Extraction can now be adapted to address situations of high water table, low permeability soils and heavier end compounds. This paper reviews these innovative modifications to the vacuum extraction process and how they solve a wide variety of subsurface contamination problems.

The modifications, or processes, reviewed include: Dual Vacuum Extraction, Vacuum Extraction-Enhanced Bioremediation, Groundwater Sparging and Pneumatic Soil Fracturing. Also included is a discussion of Soil Heating techniques.

Rapid Response and Remediation of a
Gasoline Spill La Voulte Sur Rhone, France

D. Preufert and F. Leclerc, P. Armstrong and Eur Ing. Charles Pineo

This paper is a case study of a unique team effort and rapid response to the site of a railroad accident and gasoline spill in the town of La Voulte sur Rhone, France. Within hours of the derailment and fire on January 13, 1993, the French government BRGM, as emergency response coordinator, organized a team of three French companies to mobilize equipment and personnel to the site where gasoline had spread beneath the railroad tracks and adjoining houses and streets. Catalytic oxidizers (CATOXs) were mobilized by two companies along with the necessary equipment to permit in-situ (without excavation) remediation by Vacuum Extraction to begin as soon as wells could be drilled and completed. An on-site gas chromatograph laboratory was installed. Ground water pumping limited offsite migration of gasoline and permitted recovery of floating gasoline from the water table.

Drilling operations began 2 weeks after the accident, and vapor treatment using Catalytic Oxidation began on February 5, just 3 weeks after the accident. Lessons learned from the on-going Chavanay (Loire) remediation project underway 100 km to the north prompted French authorities to act quickly to minimize the potential for the gasoline to cross a large area from the site of the train wreck. This rapid response reduced the risk of fire and explosion in the vicinity of the site and permitted residents to return to their homes within a few weeks of the accident. Site assessment was combined with vacuum extraction to expedite cleanup of the soils and minimize the potential for pollution of underlying ground water and the nearby Rhone river.

Operations at La Voulte ceased July 30, 1993. Vacuum Extraction removed approximately 21 tons of hydrocarbons in 6 months; pump and treat operations recovered 8 cubic meters (approximately 6 tons) of liquid gasoline in the same period. An large estimated volume of gasoline was removed in untreated ground water. There was no specific cleanup objective for the site. The responsible authorities, in consultation with the local administration, determined when to cease operations based on overall assessments of risk to the environment and the community.

The Use of In-Situ Dual Vacuum Extraction for
Remediation of Soil and Groundwater

Bretton E. Trowbridge, P.E. Newport Beach, CA and David E. Ott, Westford, MA

Dual Vacuum Extraction provides a rapid and cost-effective method of remediating soil and groundwater impacted by volatile organic compounds (VOCs). Dual Vacuum Extraction is the removal of both water and vapors through the same borehole by use of entrainment.

This technology provides for the remediation of the vadose zone, capillary fringe, smear zone, and existing water table. The effectiveness of this technology is shown in the following case study.

A release from an Underground Storage Tank (UST) was responsible for a hydrocarbon plume spreading over approximately 50,000 square feet. The release produced vadose zone contamination tin the silty and sandy clays from 10-30 feet below ground surface (bgs) with TPH concentrations up to 1,400 mg/kg.

In addition, a layer of free floating liquid hydrocarbon was present on a shallow aquifer located at 25 feet bgs in thicknesses ranging from 0.5 feet to 3.0 feet.

An In-Situ Dual-Extraction System was installed to remediate the soils and groundwater to levels as required by the Los Angeles Regional Water Quality Control Board (RWQCB). The system operated 24 hours/day for 196 days with an operating efficiency of over 99%.

After 196 days (28 weeks), over 17,000 pounds of hydrocarbons had been extracted from the soils.

Seven confirmatory soil borings were advanced in the area of highest initial hydrocarbon concentrations and indicated that TPH and BTEX concentrations had decreased over 99% from initial soil concentrations.

Three confirmatory groundwater samples were obtained from monitoring wells initially exhibiting up to 3 feet of floating product. Confirmatory samples exhibited non-detectable (ND) concentrations of TPH and BTEX. Based upon the positive confirmatory results, site closure was obtained from the RWQCB in May of 1991.

In only 28 weeks of operation, the groundwater contamination was reduced from free floating product to non-detectable concentrations of TPH by the use of Dual Vacuum Extraction.

Full-Scale Remediation at a Superfund Site Using
In-situ Vacuum Extraction and On-Site Regeneration Case Study - Phase I

Joseph A. Pezzullo, P.E., R. Michael Peterson, Ph.D, West Trenton, NJ; James J. Malot, P.E. San Juan, PR

A full-scale remediation of soils, bedrock and groundwater is underway at the Tyson's site near Philadelphia, Pennsylvania. Ranked number 25 on the NPL, Tyson's is a location where unknown quantities of volatile organic compounds (VOCs) and semivolatile compounds were disposed of over a period of several years. Two former waste lagoon areas are the focus of the remediation activities. The contaminated area covers approximately four acres.

The cleanup involves in-situ vacuum extraction in the silty clay soils of the former lagoons and surrounding area which contains upwards of 250,000 ppm total VOCs and semivolatiles. The major contaminants of concern are 1,2,3 trichloropropane, toluene, xylenes and dichlorobenzene, although there are also approximately 20 other identified compounds. In addition, the remedy includes dual extraction of water and vapor from the underlying fractured arkosic sandstone and the collection and treatment of the seep spring water from the off-site area down gradient of the former lagoons.

The remedy includes 180 soil vacuum extraction wells, nine dual extraction wells and six bedrock extraction wells which are manifolded to a central processing plant. The process plant covers 10,000 ft and contains two 700-hp vacuum units and two 250-hp vacuum units. The design air flowrate is approximately 15,000 scfm at 13 in. Hg vacuum. Vapor treatment is by activated carbon adsorption with on-site stream regeneration and solvent recovery. Water treatment is by air stripping with carbon polishing. Since the commencement of remediation activities in November 1988, more than 95,000 lb. of contaminants have been removed from the site by the vacuum extraction process for off-site destruction. Overall, the vacuum extraction remedy is successfully treating soils at the site with an innovative in-situ treatment process.

Vacuum Extraction Of Volatile and
Semi-Volatile Compounds at a Superfund Site

David Fuerst and Bennie Underwood, P.E. Marietta, GA

A pilot test of the Terra Vac Extraction Process was conducted at a Superfund Site in South Carolina to demonstrate the feasibility of utilizing Vacuum Extraction as the remedial technology for soils at the site. Previous investigations at the site conducted by the U.S. Environmental Protection Agency (USEPA) and others have identified volatile and semivolatile compounds in the soils.

A pilot test was conducted to demonstrate the ability of the Vacuum Extraction process to remediate the volatile and semivolatile compounds identified in the soils.

The main objectives of the pilot test were as follows:

  • Demonstrate extraction of organics from site soils and quantify site specific extraction rates of volatile and semivolatile organic compounds from the unsaturated zone.
  • Utilize a short term bench test study to demonstrate reduction of volatile and semivolatile organic compound concentrations on an undisturbed site soil column.

Three Vacuum Extraction pilot test wells were installed in July 1990. The field pilot test operations were conducted over a ten day period for a total system operating time of 190 hours. A total of approximately 1186 pounds of volatile (22 compounds quantified) and 143 pounds of semivolatile (35 compounds quantified) were extracted during the field pilot test. Examples of the volatile compounds are carbon tetrachloride, acetone, MEK, MIBK, TCA, TCE, DCA, and chlorobenzene. Examples of the semivolatiles are phenol, napthalenes, chlorophenols, methyl phenols, and cyclohexanone.

A short term bench test was conducted on two undisturbed soil columns. The bench test was operated over a ten day period for a total of 170 hours. The analytical results of the bench test indicated that substantial reductions in both VOC and semivolatile concentrations were obtained.

Initial soil phenol concentrations were reduced from 4,900 mg/kg to 2.2 mg/kg and methylphenol concentrations were reduced from 2,200 mg/kg to less than 0.33 mg/kg during the bench test.

The USEPA Record of Decision for this site has specified Vacuum Extraction as the soil remedial technique to be utilized.

Vacuum Extraction Of Hydrocarbons From
Subsurface Soils at a Gasoline Contamination Site

Joseph Applegate, John K. Gentry, P.E., and James J. Malot, P.E. San Juan, PR

Terra Vac, Inc., in cooperation with the Florida Department of Environmental Regulation (FDER), installed and tested a Vacuum Extraction system at a gasoline contamination site in Belleview, Florida where a substantial leak of unleaded gasoline had contaminated subsurface soils and groundwater.

With the increasing number of leaking underground petroleum tanks in Florida, it is essential to demonstrate new cleanup technologies that are efficient and cost-effective. The commonly used cleanup methodology consisting of free product recovery and groundwater withdrawal without soil remediation is very costly and lengthy since the contaminated soils serve a continuing source of contaminants leaching into the groundwater.

The site came to the FDER's attention in 1982 when the municipal well field, which is developed within the Floridan Aquifer, became contaminated with gasoline components and had to be abandoned. Subsequent investigation revealed that at least 10,000 gallons of unleaded gasoline had leaked between October 1979 and March 1980 from a service station located 600 feet up-gradient from the well field.

In this region of Florida, the Floridan Aquifer, which is the primary source of groundwater, is comprised of a highly karstic limestone in which dissolution has formed an extremely porous and permeable aquifer system. Due to the discontinuous nature of the overlying clay layer in the vicinity of the site, the Floridan aquifer is under water table conditions.

Thus, there is little resistance to hydrocarbons migrating into the aquifer from overlying soils containing residual hydrocarbons.

Because of the 50-foot thickness of the unsaturated zone and the large quantities of contaminants in the subsurface soils at the site, FDER sponsored a pilot study to demonstrate the effectiveness of vacuum extraction technology to treat soil contamination. The Terra Vac system is designed to recover, in-situ, both free product and adsorbed hydrocarbons, from the contaminated soil.

The objectives of the pilot study were to: (1) delineate the extent and magnitude of hydrocarbons in the subsurface; (2) quantify that hydrocarbons can be extracted; and (3) develop a conceptual design and time-frames for the cleanup of soils at the site.

The preliminary results are excellent. The Terra Vac Vacuum Extraction System recovered more than 8,000 lbs. of hydrocarbons from the subsoil during the three week-pilot test at rates of up to 2,000 lbs./day. The average recovery rate during this period was about 880 lbs/day. FDER has since extended the project to further clean up the site.

This unique extraction process solves many problems that are inherent to other cleanup alternatives by first removing the VOCs from the vadose zone and then follow with groundwater recovery and treatment, if required. For VOC soil contamination, the Terra Vac Vacuum Extraction System is cost effective and is a total approach to decontamination.

Unsaturated Zone Monitoring And
Recovery Of Underground Contamination

James J. Malot, P.E. San Juan, PR

Terra Vac has developed a new method for monitoring underground contamination and recovering contaminants before they reach the water table. This innovative method uses Vacuum Extraction Technology, applied to the subsurface soils or bedrock beneath storage facilities, spills sites or pipelines.

The system is most effective for detecting and recovering chemicals such as volatile organic compounds, solvents and petroleum products. Users can install the system in any hydrogeological setting regardless of the depth to the groundwater. Monitoring of underground storage tanks, landfills, lagoons and pipelines with this system can detect potential contaminants before they reach the aquifer and develop into costly groundwater problems.

With proper design, the same system used to monitor the unsaturated zone can also recover contaminants without further installation of subsurface equipment. Successful application of this new technology recovered more than 300 pounds of carbon tetrachloride per day that leaked from unsuspected corrosion holes in the bottom of an underground tank.

The method has monitored and recovered, among other pollutants, methylene chloride, hexane, acetone, methanol and gasoline. Terra Vac has installed monitoring and recovery systems in clayey soil, sand and limestone rock formations. Detecting leaks from underground storage tanks, spills from transfer operations and leachate from landfills is especially effective with this method when groundwater is relatively deep.

Superfund Site Soil Remediation Using Large-Scale Vacuum Extraction

Ed Malmanis Marietta, GA, David W. Fuerst, Windsor, NJ, and Robert J. Piniewski Temperance, MI

Full-scale remediation of soils contaminated with various volatile organic compounds (VOCs) was implemented at a Superfund Site in Michigan. The U.S. EPA's ROD specified Vacuum Extraction for the soil remediation. The site previously had been a facility used for the storage and transfer of industrial solvents. Twenty-one underground storage tanks still exist at the site.

A pilot-phase cleanup project, conducted in late 1987, utilized four soil vacuum extraction wells to verify design parameters for the full-scale system. During the pilot -phase extraction, rates of VOCs (including PCE, TCE, and 20 other identified VOCs) reached a maximum of 4,400 lbs./day, with extracted air flow rates ranging up to 165 cfm per well. Subsurface vacuum measurements indicated a radius of influence of up to 75 ft was achieved.

A full-scale system consisting of 23 vacuum extraction wells, two Vacuum Extraction units and a vapor phase carbon adsorption emission control system was started up in March 1988. Since remediation of soils was started, over 28,675 lbs. of VOCs have been removed from the soils at this site by Vacuum Extraction.

Integrated Vacuum Extraction/Groundwater
Sparging For Rapid, Cost-Effective Remediation

James P. Keegan, Newport Beach,CA

Vacuum Extraction (VE) has been proven to effectively remove volatile organic compounds (VOCs) and effectively remediate soils.

Groundwater sparging (GWS) is an enhancement technique that has been developed to allow for the in-situ removal of VOCs from both soil and groundwater. Integrated vacuum extraction/groundwater sparging systems have demonstrated their capability of performing effective remediation of both soils and groundwater in-situ.

Groundwater sparging involves the injection of contaminant-free gas into the saturated zone to effect partitioning of adsorbed and dissolved VOCs to the vapor phase and the recovery and control of the VOCs with VE. Effective implementation of these techniques can result in significant cost and time savings.

Application, design and implementation of these integrated systems is dependent on a number of site specific restrictions and design considerations. Among these considerations are hydrogeologic conditions and engineering controls. Hydrogeologic conditions must be evaluated to determined the feasibility of an integrated VE/GWS system. Conditions such as a homogeneous soil of medium to high permeability are optimal for effective implementation of these cost saving measures.

Engineering controls for prevention of forced migration of the contaminant are also imperative for regulatory approval in most cases. Such controls as strategically located monitoring wells, VE wells and even groundwater recovery wells may be required.

This paper will focus on a brief description of the integrated VE/GWS technology. Also presented is a case study were an integrated VE/GWS system was used to remediate a site in California. At this site groundwater concentrations were non-detect in one month of sparging operations.

Full Scale Vacuum Extraction Remediation
*Michigan Superfund Site*

Ed Malmanis Marietta, GA, and Robert McClenahan

Implementation of a full-scale remediation of soils contaminated with various volatile organic compounds (VOCs ) was conducted at a Superfund Site in Michigan. Twenty-one underground storage tanks will be removed once the soil remediation is completed, as required by the EPA Record of Decision.

The remediation was conducted in two phases, a pilot phase, and subsequent scale-up to a full-scale system based on the pilot phase field data. The full-scale system included twenty-three wells, two Vacuum Extraction units, an activated vapor phase carbon system and instrumentation to allow unattended operation. An on-site gas chromatograph has been used to monitor the system's performance.

After approximately 160 days of operations an estimated 40,000 pounds of VOCs have been removed from the soils at the site, with initial VOC extraction rates as high as 4400 pounds per day.

Operating results to date including mid point operation soil sampling indicates that all liquid phase VOCs have been removed and soils generally have been remediated to near clean-up objective levels with the exception of a number of isolated hot-spots which have been slower to remediate due to subsurface structures. Changes to the existing system were made to address the remaining subsurface VOCs. The activated carbon system was replaced with a Catalytic Oxidizer.

Bioremediation Of Petroleum Hydrocarbon
Contaminated Soils Using Soil Vapor Extraction: Case Study

Robert J. Roth, Ph.D., P.E. and R. Michael Peterson, Ph.D., West Trenton, NJ

Soils contaminated with petroleum hydrocarbons are being remediated in-situ at a site in Lakewood, New Jersey by Bioremediation in conjunction with Soil Vapor Extraction (SVE) and nutrient addition. The contaminants were from hydraulic oils which leaked from subsurface hydraulic lifts, waste oil from leaking underground storage tanks (USTs), an aboveground storage tank, and motor oil from a leaking UST. The oils contaminated subsurface soils at the site to a depth of 25 feet . Approximately 900 cubic yards of soil were contaminated. Soil sample analyses showed total petroleum hydrocarbon (TPH) concentrations up to 31,500 ppm. The design of the remedial system utilized the results of a treatability study which showed that TPH degrading microorganisms, when supplied with oxygen and nutrients, affected a 14% reduction in TPH in 30 days. A SVE system consisting of three wells, each installed to a depth of 25 feet below grade, was operated to achieve an extracted air flow of approximately 20 to 30 scfm from each well. Bioremediation of the TPH was monitored by measuring CO2 and O2 concentrations at the wellheads and vapor monitoring probes. After four months of remediation, CO2 concentrations were at a minimum, at which point the subsurface soils were sampled and analyzed for TPH. The soil analyses showed a removal of TPH by biodegradation of up to 99.8% after four months of remediation.

Efficient and Cost-Effective Programs for
Soils and Groundwater Restoration

Joseph A. Pezzullo Windsor, NJ and Bretton E. Trowbridge Newport Beach, CA

As the nations of the world struggle with the complexities of cleanup of the hazardous waste which already exists and attempt to control and manage the discharge of more wastes, they are caught in a dilemma between a plethora of regulatory guidelines and the limitations of technology development. It is difficult to enforce regulations on industry if there is no technology available to remediate the waste.

Usually, the most serious form of hazardous waste is that which cannot be seen; waste that is in the soils and groundwater.

The wastes, commonly in the form of petroleum hydrocarbons, volatile organic compounds, and inorganic compounds, slowly leach through the soils and into the groundwater where conventional methods of remediation may take decades, and the costs may become outrageous. More effective means of subsurface remediation may be accomplished by treatment of the contamination at the source and managing the migration of the contaminants away from the source.

Complex subsurface contamination problems require innovative solutions, and fortunately, for the most part, the advances of technology have depth pace with the regulatory environment.

This paper presents three common, yet complex, cases of subsurface contamination where both soils and groundwater were restored by the application of innovative and cost effective remedial measures.