Cleanup levels

The different forms of lead have different bioavailabiUty and this ultimately impacts cleanup levels. Mine tailings, slag, and other such residues have limited impact on blood lead levels because these materials contain lead in the form of lead sulfide, which has limited biological reactivity and uptake. 

They may be favored over in situ treatment where they will reduce cleanup times, their operation and capabiHties are considered more reHable or better understood, or they can achieve lower cleanup levels. Both in situ and ex situ treatment for soil and ground water rely on a combination of unit processes, which often include biological degradation of organics. 

The time to cleanup may actually be somewhat less than 9 years if Pb migrates down in the soil profile with the addition of EDTA, or if tillage practices serve to smooth out the hot spots. Regulatory cleanup levels are usually based on a limit that cannot be exceeded, such as 400 mg/kg, and soil concentrations would need to be analyzed to ensure compliance at the end of each year. 

While U.S. EPA has not promulgated a federal cleanup level for MTBE, some states have established cleanup levels. However, these vary by state, ranging from 5 to 202,000 pg/L, a difference of more than three orders of magnitude.1 Because of the variation in MTBE cleanup levels, after-treatment MTBE concentrations are reported based on information provided in the source documents, and are not compared against a common cleanup level for all projects. 

Only limited information is available about the health risks of oxygenates other than MTBE. Fewer states have established standards and cleanup levels for these contaminants than for MTBE. Currently, there are no federal drinking water advisory or cleanup levels for these other fuel oxygenates. Several states have established, and some states have plans to establish, cleanup levels for other oxygenates.21 Table 24.1 summarizes the number of states that have cleanup levels for fuel oxygenates along with the range of cleanup levels established for each. 

State Cleanup Levels for Fuel Oxygenates in Groundwater... 

Fuel Oxygenate States with Cleanup Level 2004 Lowest Cleanup Level (pg/L) Highest Cleanup Level (pg/L)... 

May not be capable of reaching very stringent soil cleanup levels (soil concentrations may reach an asymptotic level that is higher than the cleanup level). 

Because of the heightened interest in bioremediation of TBA, additional information was obtained about several of these sites. These data, provided in the online database, show that several sites were able to reduce the concentration of TBA, sometimes to less than its site-specific cleanup level. For example, at several sites in Texas, including Turtle Bayou Easement Area and Rural Area Disposal Area, in situ bioremediation was used in conjunction with other technologies such as SVE, and in situ thermal desorption. At these sites, the concentrations of TBA were reduced to less than its cleanup goal, with concentrations after treatment ranging from 100 to 1000 pg/L. At the Naval Base Ventura County, Port Hueneme, California, in situ bioremediation was used in a biobarrier configuration, and the concentration of TBA was reduced from >1000 to <5 pg/L. 

Delta Environmental Consultants, Groundwater Oxygenate Cleanup Levels for LUST Sites, United States Environmental Protection Agency, Washington, DC. Available at www.epa.gov/oust/MTBE/ MTBEtable.pdf, 2004. 

Careful planning of the initial investigation activities is very important because this task sets the stage for future decisions and actions. Physical site characteristics, extent and intensity of contamination, cultural features, and historical background are confirmed in this project phase. Cleanup levels, potential remedial schemes, and probable costs are established with the data derived from the initial work. Regulators typically set conservative closure standards to assure public safety. Once these are established, it is difficult to modify them. Therefore, a truly representative site investigation must be completed before any remediation levels are set. 

Caution must be used, however, because inexperienced investigators often try to use estimated data instead of actual analyses. While estimates reduce sampling and analysis costs, safe use of estimated data requires that it be conservative. Experienced investigators strike a balance between estimates and field sampling to save costs without sacrificing cleanup levels. 

Natural attenuation should not be perceived as a permanent remedy or as a means to achieve certain cleanup levels, but rather as (1) an interim measure until future technologies are developed, (2) a managerial tool for reducing site risks, and (3) a bridge from active engineering (i.e., pump-and-treat, vapor extraction, etc.) to no further action. 

The analysis for the total petroleum hydrocarbons (TPHs) in a sample as a means of evaluating petroleum-contaminated sites is also an analytical method in common use. The data are used to establish target cleanup levels for soil or water by regulatory agencies in the United States and in many other countries. 

There are several reasons why the data for total petroleum hydrocarbons do not provide ideal information for investigating sites and establishing target cleanup criteria. For example, use of the term total petroleum hydrocarbons suggests that the analytical method measures the combined concentration of all petroleum-derived hydrocarbons, thereby giving an accurate indication of site contamination. But this is not always the case. Furthermore, target cleanup levels based on total petroleum hydrocarbons concentrations implicitly assume (1) that the data are an accurate measurement of petroleum-derived hydrocarbon concentration, and (2) the data also indicate the level of risk associated with the contamination. These assumptions are not correct due to many factors, including the nonspecificity of some of the methods used and the complex nature of petroleum hydrocarbons and their interaction with the environment over time. 

The cost of remediation is often presented in terms of dollars to achieve a final cleanup level at a site however, that approach could not be applied in this situation because no final cleanup criteria for air or soil had been established for the SITE project. The cost estimate for TCE removal is instead based on TCE removal rates that were extrapolated from a 4-hour test to a 1-year cleanup period (D10589F, p. 14). 

According to the vendor, cost for this technology is site specific, being highly dependent on type and concentration of contaminants and required cleanup levels (personal communication John Strey, Catalytic Combustion Corporation, 1996). 

The cost of the Daramend process varies depending on the type and amount of contaminants present, the soil type, amount of contaminated soil, monitoring and pretreatment requirements, and the required cleanup levels. The location of the site can also affect the overall cost of the project. The site s climate and distance from the source of equipment, supplies, and personnel will infiuence the cost of the remediation project (D11494D D20080W, p. 42). 

Note that multiple applications may be required to achieve target cleanup levels (D14277I). The Model T Jr. Foamer, the cleaning system sold by Integrated Chemistries, Inc., for application of Capsur, costs 2900. 

Soil characteristics, initial contaminant concentrations, and target cleanup levels all have significant impacts on the cost of slurry-phase bioremediation. In 1993, the cost of treatment was estimated to be 100 to 150/m of waste treated (D10336W, p. 33). For groundwater contaminated with 100 to 2000 parts per million (ppm) of PAHs, SBP estimated treatment costs to range from 0.10 to 0.40/gal (D10055Q, p. 25). 

Pilot tests are needed at each site to confirm cost assumptions. Factors that affect cost include soil moisture, depth of contamination, desired cleanup level, and types of contaminants present. 

Estimated unit prices for treatment of VOCs using the PADRE vapor treatment process range between 1.00 and 3.00/lb. The initial contaminant concentration, volume of gas stream to be treated, and target cleanup levels have signihcant impact on unit price. These price estimates do not necessarily include all indirect costs associated with treatment, such as excavation, permits, and treatment of residuals (D13375F, p. 15). 

According to the Westinghouse Savannah River Company, in situ bioremediation with natural gas injection quickly degrades and removes contaminants, is cost effective, produces no harmful side effects, and may be applicable to benzene, toluene, and other biodegradable organics where cleanup levels of less than 10 ppm are required. 

The engineered soil cell is a hybrid of the landfarming and the composting processes. Engineered soil cells are constructed, essentially, as aerated compost piles. Such systems offer the best of both processes and are therefore preferred whenever the site-specific application warrants their use. Key factors to consider include (1) ability to excavate and process material, (2) total volume of material to be treated, (3) expected treatment time, and (4) desired cleanup level. 

PAUSTENBACH, D.J., WENNING, R.J., LAU, V., HARRINGTON, N.W., RENNIX, D.K. and PARSONS, A.H. (1992). Recent developments on the hazards posed by 2,3,7,8-tetrachlordibenzo-p-dioxin in soil Implications for setting risk-based cleanup levels at residential and industrial sites, J. Toxicol. Environ. Health 36, 103-148. 

An example of a concentration limit is a cleanup level, which is a type of an action level used in remediation projects. Pollutant concentrations in an environmental medium that are greater than the cleanup levels warrant a remedial action. Cleanup levels are often developed based on site conditions, such as future land use exposure pathways the presence of groundwater and the likelihood of its beneficial use the presence of specific ecological receptors background concentrations. 

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