Our outstanding team of scientists and technicians includes a senior environmental scientist (V.W. Jamison) who is one of the acknowledged pioneers in this field having been actively involved since 1971. The following selected project summaries are representative of our experience in the field of bioremediation. R.L. Raymond, Sr. and V.W. Jamison were granted a patent for their process. (U.S.Patent No.3,846,290 Nov. 5, 1974)

Project 3 is in the final monitoring stage for closure. Project 4 was one of the first bioremediation projects successfully closed in California. Projects 5, 6, and 7 are examples of ex-situ bioremediation. Projects 8 to 11 are examples of accelerated anaerobic bioremediation projects for clean-up of chlorinated solvent-contaminated groundwater.

ACTION TAKEN: The gasoline-utilizing microbial population was stimulated by the addition of nitrogen, phosphorus, and dissolved oxygen. Dissolved oxygen was supplied by sparging air into wells with diffusers connected to paint sprayer-type compressors. Ground water flow was controlled by a series of injection and withdrawal wells.

EFFECTIVENESS: Estimates based on the amount of nitrogen and phosphate retained in the aquifer suggested that from 744 to 944 barrels of gasoline were degraded. The amount of free gasoline in the wells declined as the nutrient addition program continued. The levels of gasoline in the produced water were not reduced during the period of nutrient addition, but no gasoline was found in the produced water ten months later. Bacterial levels increased greatly in the ground water. The biostimulation programs met its objective of removing the hydrocarbons from the ground water to the satisfaction of the governmental agency overseeing the project.

ACTION TAKEN: A biostimulation program was begun. Nutrients including ammonium sulfate, disodium phosphate, monosodium phosphate, sodium carbonate, calcium chloride- dihydrate, magnesium sulfate-monohydrate, manganese sulfate-monohydrate and ferrous sulfate-heptahydrate were added to the wells continuously or in batches. Air was introduced into the wells by a carborundum diffuser with an output of 10 SCFM. Producing wells were used to control ground water flow.

EFFECTIVENESS: The biostimulation program was not completely successful; residual gasoline was found at the last sampling period, but no free hydrocarbon was observed in any of the wells after the biostimulation program ended.The gasoline concentrations in cores taken from the aquifer did not seem to change substantially during the biostimulation program. Gasoline was found in the produced water which indicated that pockets of gasoline remained in the aquifer. One well which did not receive nutrients and air was still contaminated with gasoline. After the area near this well was treated, no free gasoline was found in any of the wells, and operations ceased with state approval. Microbial growth and utilization of nutrients and dissolved oxygen backed up the conclusion that enhanced microbial degradation was responsible for the removal of the gasoline.

ACTION TAKEN: We acted as the principal bioremediation contractor for this cleanup project. During a two year period of the bioreclamation phase, approximately 30,000 gallons of gasoline were biologically degraded at the site. To the best of our knowledge, this was the first in-situ bioreclamation project in the United States to use a large quantity of hydrogen peroxide to supply 0xygen for the cleanup. Producing wells were used to control ground water flow and infiltration galleries utilized for nutrient introduction.

EFFECTIVENESS: Due to the bioreclamation program, approximately 30.000 gallons of gasoline were biologically removed. Homeowners have been able to return to their homes. Free product has not been reported in any of the cleanup area monitoring wells. Total gasoline in the ground water in the treated area has been non-detectable. A limited monitoring program is ongoing.

ACTION TAKEN: A bioreclamation program was chosen as the most cost effective remediation technique with the capability to meet the stringent state cleanup requirements. Nutrient and oxygen formulations were added to infiltration wells in batches. Hydrogen peroxide was used as the oxygen source for this project. Producing wells were used to control ground water flow at the site.

EFFECTIVENESS: This was the first bioremediation project in the state of California that was successfully closed under the tough new cleanup guidelines.

ACTION TAKEN: An ex-situ bioremediation treatment system was designed and installed to treat the 1,600 cubic yards of contaminated soil. The contaminated soil was placed in the treatment cell in a 12 inch lift. Custom blended nutrients were added to the contaminated soil and oxygen was introduced by rototilling on a periodic basis.

EFFECTIVENESS: Closure is anticipated to be approved in December, 1993.

ACTION TAKEN: A combination of traditional in-situ bioremediation and bioventing is being used to remediate the site. The groundwater recirculation and vacuum extraction system were installed in June, 1993. Full system start up began in August, 1993.

EFFECTIVENESS: The project is currently ongoing.

ACTION TAKEN: Ex-situ bioremediation is being used as the primary remediation technology for this site. The contaminated soils are excavated and screened prior to placement in biobeds for treatment. The windrow method of landfarming is being used in the bioremediation process. A custom blended nutrient formulation is added to each biobed. Biological process monitoring and soil analysis is conducted in an onsite laboratory.

EFFECTIVENESS: The project is currently ongoing.

ACTION TAKEN: A 60 foot long by 40 foot wide recirculating pilot with three injection and three extraction wells was established in one area of the Dover Air Force Base and has been fed lactate and nutrients alternately. TCE was degraded to cDCE in the pilot after nine months once reducing conditions were achieved in the aquifer as a result of the lactate additions. No further degradation of the cDCE was observed, consistent with the laboratory treatability studies. At this time, it was decided to bioaugment with a dechlorinating enrichment culture isolated from a site in Florida. Under the direction of Dr. Lee, 350 liters of the culture were grown up and added to the center injection well in the pilot area. Three months after the bioaugmentation, dechlorination of the cDCE to VC and ethene was observed. Over 99.5% of the TCE and cDCE within the center leg of the pilot cell was degraded to ethene. The dechlorinating culture has moved with the groundwater throughout the entire cell. Treatment of the contaminated groundwater without recirculation was successful in degrading the chlorinated solvents. A minimum of 10 mg/L of organic carbon was needed to support complete dechlorination. Batch weekly additions of substrate supported dechlorination and provided an adequate distribution of substrate while avoiding biofouling of the injection well.

EFFECTIVENESS: This was the first successful demonstration of bioaugmentation to completely degrade chlorinated ethenes. It opens up the possibility for treatment of many sites where the native microbial population is not capable of completely biodegrading the chlorinated solvents. The accelerated anaerobic bioremediation process is being scaled-up to treat one of the source areas at Dover Air Force Base.

ACTION TAKEN: Lab studies were performed by TSI to assess the impact of introduction of the insoluble substrate on the hydraulic conductivity of subsurface materials and to predict the expected mobility of the substrate in the aquifer. Two barrier configurations were designed: (1) closely spaced injection points for the emplacement of the insoluble food grade substrate and (2) more widely spaced injection points for the emplacement of emulsified substrate. The substrate and emulsifying agents were food-grade products. This allowed for prompt approval from the Delaware Department of Natural resources and Environmental Control (DNREC).

The barriers were installed side-by-side, perpendicular to the groundwater flow direction. A Geoprobeâ was used to install both the injection points and several closely spaced monitoring wells placed on either side of both barriers. Insoluble substrate or emulsified substrate was injected under pressure into the aquifer formation.

EFFECTIVENESS: The radius of migration of each substrate away from the injection points, the changes in hydraulic conductivity of the aquifer, and degradation of the contaminants are being monitored over time. Initial results suggest rapid removal of chlorinated solvents from the groundwater. Some of the removal was a result of adsorption of contaminants into the oil. Reductive dechlorination of TCE to cDCE has been promoted, however further transformation onto vinyl chloride and ethene or ethane has been limited. Relatively little transformation of 1,1,1-trichloroethane and its daughter products has been observed other than production of chloroethane in some wells. Based on the results to date and our experience with a pilot in another area of the base, we anticipate that bioaugmentation will be required to achieve complete dechlorination of these compounds. The specific capacity of the barrier receiving the emulsion was reduced by approximately two orders of magnitude. TOC levels were elevated up to 15 feet away from the emulsion barrier for over eighteen months.

ACTION TAKEN: A grid of 6 injection points for emplacement of the emulsified substrate was installed using a Geoprobeâ direct push unit. Emulsified substrate was injected in a zone from 25 to 50 feet below ground surface. A second application of the emulsified substrate was conducted after 16 months to maintain reducing conditions and further promote reductive dechlorination in a somewhat larger treatment area.

EFFECTIVENESS: The formation accepted the emulsified substrate easily. The emulsion appeared in several monitoring wells suggesting that the radius of migration of the substrate was as much as 30 feet from the point of injection. Degradation of the contaminants is being monitored over time. We have observed decreases in the parent compounds and increases in the daughter products including ethene and ethane within the first month and a half after substrate addition. After 16 months, the average concentration of the total volatile contaminants had been reduced by 66%. Degradation rates for the total volatile contaminants over the 495 day treatment period were as high as 394 mg/L-day in a well with greater than 100,000 mg/L total volatiles. In areas with lower concentrations, total VOC degradation rates were lower, in the range of 2.8 to 24 mg/L-day. A second application of the soybean emulsion was performed in February 2002.

ACTION TAKEN: For the SS-17 pilot, six injection wells screened from 8 to 18 feet below land surface were installed using a hollow stem auger drilling rig. Four injection wells and six monitoring wells were sampled in November and December 2001 and in April 2002. Two injection wells were installed for the OU-1 pilot. One of the wells was bioaugmented with groundwater from the SS-17 pilot area thought to contain a dechlorinating enrichment. The emulsified substrate package was injected into the injection wells in December 2001.

EFFECTIVENESS: In the SS-17 pilot, the emulsified substrate was distributed up to 25 feet away from the barrier. Over the first four months of monitoring, the emulsion has enhanced dechlorination of TCE and cDCE to VC, ethene, and ethane. For example, well NB had 0.15 mM TCE, 1.0 mM cDCE, 0.90 mM tDCE, 0.83 mM VC, 0.11 mM ethene, and 0.057 mM ethane in November 2001. In April 2002, this well contained <0.043 mM TCE, 0.065 mM cDCE, 0.10 mM tDCE, 0.19 mM VC, 0.39 mM ethene, and 0.13 mM ethane. The percent ethene and ethane relative to total chlorinated ethenes increased from 5.8 to 59% in well NB. The percent ethene + ethane in all wells in the SS-17 pilot ranged from 9 to 99%.

The OU-1 injection wells also showed large increases in the ethene and ethane concentrations between November 2001 and April 2002. The percent ethene + ethane increased from 0 to between 20 and 46% in the two injection wells. Bioaugmentation with the groundwater from the SS-17 plume did not improve the extent of dechlorination. Because neither pilot has shown appreciable concentrations of acetylene, the abiotic reaction of TCE with ferrous sulfide does not appear to be occurring.

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