Superfund Soil Treatment

Treatability studies were performed on actual soils from a Superfund site located in the northeast United States. The site was contaminated with heavy metals, in particular, cobalt, cadmium and nickel. These contaminants ranged in concentrations from 3000-5000 mg/kg. 

The results of the metals concentration of the three reagent ratios did not vary significantly from each other. Ratio B was chosen as optimal when examining all factors, i.e. UCS, material handling and characteristics and economics. 

In order to test the long term stability of the CHEMFIX process, the Multiple Extraction Procedure (MEP) was performed on the soil samples treated with the optimal, reagent ratio B. These results are illustrated in Table 6. 

The results showed that there was no increase in leachate metals concentration after ten extractions. Most of the metal concentrations remained the same or decreased during the total MEP run. This proves the long term stability of the CHEMFIX product since the MEP was designed to simulate conditions of 1000 years of acid rain exposure. In addition, throughout the entire MEP analysis the leachable metals concentrations were all below the regulatory limits. Thus once the soil is treated by the CHEMFIX process it remains non-hazardous for extended periods of time. 

TCLP RESULTS OF CHEMFIX PRODUCTS FOR SUPERFUND SOILS 

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Equipment for Superfund Waste Shipment RCRA hazardous waste that has been spilled, improperly landfilled, or dredged from defunct lagoons is a CERCLA waste, more commonly referred to as a Superfuna waste. For clean-ups where offsite treatment is the chosen solution, soil is excavated and placed in 15-m roll-off box or dump body truck. The trucks may be lined with polyethylene to reduce... 

According to a U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE) report, treatment costs for the BioGenesis soil washing technology are affected by the following factors ... 

BioTrol soil washing system costs for the MacGilhs and Gibbs Superfund site in New Brighton, Minnesota, were examined on both an integrated and a unit process basis. Costs for the demonstration study were extrapolated to full-scale treatment of the wood preserving site. The extrapolation included both operating costs and capital costs amortized over an assumed 10-year equipment life span. Costs were estimated in 1991 dollars. 

At the Brown and Bryant Superfund Site, in Arvin, California, soil washing operations resulted in the production of 100,000 gal of wash water containing 400 to 600 ppm of Dinoseb. A Rayox system was implemented at the site that used ozonation followed by UV/peroxide treatment. The operating cost for this project was 40 per 1000 gal (D17097S, Appendix II). 

A Chloro-Cat catalytic oxidizer was used with SVE at a Superfund Site in Deer Park, New York, to treat VOCs and SVOCs in soils. The total treatment cost for this application was 450,420. The costs associated with instrumentation were greater than anticipated due to corrosion of process duct work. Unit costs for this application were estimated to be 360/yd of soil treated (D13943P, p.192 D22776T, p.2). 

In 1991, the SERF was demonstrated at the Rainbow Disposal site in Huntington Beach, California, under the Environmental Frotection Agency s (EFA s) Superfund Innovative Technology Evaluation (SITE) program. Total costs for the remediation at the site was approximately 4,400,000. This cost does not include legal fees. The total amount of soil that was considered to have undergone treatment was 95,000 yd, which includes the volume of soil within the treatment perimeter between the depths of 20 and 40 ft. This yields a treatment cost of 43/yd (D15382M, p. 7). 

ISOTEC was chosen to treat soils contaminated with dense non-aqueous-phase liquids (DNAPLs) at a Superfund site in Florida. With a projected cost of 340,000, ISOTEC was cheaper than the alternative technologies considered. The estimated cost for implementing six-phase heating at the site was 535,000, and the estimated cost for excavation and ex situ treatment was 835,000 (D21478I, pp. 10, 11). 

At the Sand Creek Superfund site, project costs were 2.14 million. This value does not include the cost for demobilization activities. It was determined that 81,231 of the total cost of the project was spent on mobilization and other pretreatment activities. Activities relating to treatment accounted for 2,058,564 of the total project cost. This corresponds to a treatment cost of 39 to 65/yd of soil treated and 11.70/lb of VOCs removed (D22777U, p. 23). 

At the Sikes Disposal Pits Superfund site in Crosby, Texas, an HTTS unit was used to treat hazardous organic compounds including phenolic compounds, xylene, benzene, polynuclear aromatic hydrocarbons (PAHs), toluene, creosote, dichloroethane (DCA), vinyl chloride, and naphthalene (D184581, p. 216). The estimated treatment cost was 115 million including approximately 20 million in capital costs and 95 million in operation and maintenance costs. The estimated total cost for thermal treatment was 81 million. A total of 496,000 tons of soil and debris were incinerated. This corresponds to a total unit cost for incineration of 230 per ton and a unit cost of 160 per ton for thermal treatment (D184581, p. 227). 

In 1993 through 1994, an IRV-100 thermal desorption unit was used to treat 13,986 yd of soil contaminated with trichloroethene (TCE) at the U.S. Department of Defense s (DOD s) Letterkenny Army Depot Superfund Site in Chambersburg, Pennsylvania. The total project costs were 5,402,801. This figure included 4,647,632 for McLaren/Hart s application of the thermal treatment, 192,827 for the DOD s design and projeet remediation, 249,320 for the DOD s design contract, and 312,320 for the DOD s construction contract management (D21039Z, p. 59). 

Based on pilot-scale studies at the Rocky Mountain Arsenal Superfund site near Denver, Colorado, the vendor calculated cost estimates for a full-scale B.E.S.T. unit using two separate treatment scenarios. Scenario 1 involved treating 2,840,000 yd of contaminated soil over 7 years, and scenario 2 involved treating 616,900 yd of contaminated soil over 2 years. The vendor estimated the cost of full-scale treatment would be 119 per ton for scenario 1 and 133 for scenario 2 (D15906S, p. 101). 

Total cost for the Wide Beach Development site was 12,500,000, or 298 per ton of soU treated. Total cost for the Waukegan Harbor Superfund site was 4,274,000, or 264 per ton of soil treated. Direct treatment costs for Waukegan were 3,374,000 and the mobilization costs were 900,000 (D194869, pp. 16-17). Costs associated with the SITE demonstrations are summarized in Tables 1 and 2. 

At a Superfund site in Battle Creek, Michigan, DVE was nsed as part of a larger SVE system to treat 26,700 yd of VOC-contaminated soil. Excluding before-treatment cost elements, total remediation expenses at the site were 1,645,281. This valne translates to 62/yd of soil treated, or 37/lb of contaminant removed. Before-treatment costs at the site eqnaled 535,180. The EPA notes that overall costs at this site were higher becanse of the extensive sampling and analysis that were required (D13945R, pp. 225, 227 D125053, p. 871). 

All estimated costs for the full-scale VRU are based on results from the pilot-scale unit tested at the U.S. EPA s Superfund Innovative Technology Evaluation (SITE) program, and aU costs are given in 1993 U.S. dollars. At this demonstration, the unit treated 100 lb of soil per hour. The full-scale unit is expected to have a treatment capacity of 10 tons per hour (tph). 

A pilot-scale CMS unit was evaluated by the U.S. EPA s Superfund Innovative Technology Evaluation (SITE) Emerging Technology Program in 1994. During the demonstration, 5000 lb of soil contaminated with arsenic, lead cadmium, and chromium were processed (D17201A). The vendor stated that the treatment costs for the evaluation were 100 per ton (D13902G, pp. 15, 30). 

The treatment of heavy metal contaminated soil has become an important issue in the past few years. Nearly one-third of the sites on the Superfund National Priorities List (NPL) possess lead concentrations significantly higher than normal background levels.(U The difficulties in treating heavy metal contamination stems from the fact that they cannot be destroyed or biodegraded. 

The dehalogenation process has been approved by the EPA s Office of Toxic Substances for PCB treatment and has been experimentally implemented for the cleanup of PCB-contaminated soil at the following three Superfund sites Wide Beach in Erie County, New York (1985) Re-Solve in Massachusetts (1987) and Sol Lynn in Texas (1988). The glycolate process has been used to successfully treat contaminant concentrations of PCBs from less than 2 ppm to reportedly as high as 45,000 ppm. Using this technology, Helland et al. (1995) investigated reductive dechlorination of carbon tetrachloride with elemental iron and found that the rate of dechlorination to chloroform and methylene chloride was a fast first-order process. 

One technology suitable for remediating these sites is thermal desorption, which heats soils and sludge to remove volatile contaminants such as VOCs, SVOCs, PAHs, PCBs, pesticides, mercury, and mixed waste for recovery or further treatment. The success of thermal desorption is evidenced by how frequently it has been used since its initial demonstration. From fiscal years (October 1 through September 30) 1982 through 1999, thermal desorption was used in 14% of Superfund... 

Thermal desorption systems can be broken into three key components pretreatment, the TDU, and posttreatment (Fig. 1) as discussed below. Additionally, thermal desorption systems are often used in conjunction with other treatment technologies as part of a treatment train. At previous RCRA and Superfund sites, thermal desorption has been used in conjunction with bioremediation, dechlorination, incineration, soil vapor extraction, soil washing, and solidification/ stabilization. " In these cases, the combination of technologies was required to meet the site s cleanup goals. 

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