Remedies strategies-costs

The remedial strategies of concern focus on how to select a remedial method and how to complete the remediation at the most effective cost. 

Definitions of the extent, type, and concentration of soil contamination are the primary factors that control the cost of soil remediation. The economic effectiveness of a remediation strategy depends on the following ... 

For the most part, regulators are reluctant to embrace remediation strategies that rely only on containment (i.e., without some mass removal). The need to supplement the use of vertical barriers with other measures (e.g., pumping) detracts from the overall cost-effectiveness. 

An alternative remediation strategy is to exploit higher plants that are capable of taking up exceptional amounts of metals and metalloids from the soil solution and confine it in the aboveground plant tissues. These plants have been termed as hyperaccumulators and their unique property is exploited in the in situ remediation technology of phytoremediation, which is ecologically safe, cost effective, and easy... 

Laboratory experiments, transport modeling, field data, and engineering cost analysis provide complementary information to be used in an assessment of the viability of an MNA approach for a site. Information from kinetic sorption/ desorption experiments, selective extraction experiments, reactive transport modeling, and historical case analyses of plumes at several UMTRA sites can be used to establish a framework for evaluation of MNA for uranium contamination (Brady et al, 1998, 2002 Bryan and Siegel, 1998 Jove-Colon et al, 2001). The results of a recent project conducted at the Hanford 100-N site provided information for evaluation of MNA for a °Sr plume that has reached the Columbia River (Kelley et al, 2002). The study included strontium sorption-desorption studies, strontium transport and hydrologic modeling of the near-river system, and evaluation of the comparative costs and predicted effectiveness of alternative remediation strategies. 

CORA was also used for regulatory support for the Resource Conservation and Recovery Act (RCRA) and for analyzing corrective-action strategies and costs for the RCRA Location Standards Rule. The model is being used to screen and evaluate technologies and remediation strategies for the Department of Defense. 

Factors that must be considered in developing a remediation strategy include the chemical nature, quantity, and location of the contaminants the permeability of the soil and how soil interacts with contaminants and how various cleanup or containment methods may impact workers, the community, and remediation costs. 

Reburial of waterlogged wood in the marine environment is now becoming increasingly common practice in managing wooden historic wrecks in situ, predominantly due to the prohibitive conservation costs. Remedial strategies that are appropriate and cost-effective are fundamental pre-requisites for the successful long-term management of underwater wreck sites. 

Although excellent removal efficiencies can be achieved at bench scale by the use of different enhanced electrochemical remediation strategies, several practical problems arise in using them at actual field sites. These problems include high cost... 

Because of the heterogeneous spatial distribution of physical and chemical parameters such as hydraulic conductivity, Fe(II)/Fe(III)-mineral content models of aquifer systems are mostly limited by an insufficient amoimt of input data. The idea of virtual aquifers is to engineer a data set describing a virtual aquifer system in the computer as realistically as possible in order to simulate different monitoring and remediation strategies. The quality and limitations of such strategies can be evaluated without measurement of concentrations in the field, which is costly and not very helpful for this task. The capabilities of virtual aquifers to identify and solve problems in evaluation of natural attenuation processes will be presented in three examples. 

The oxidation state of contaminants, such as U and Cr, dictate their fate and transport within the environments. The mobility and, hence, risk associated with U(VI) and Cr(VI) decreases upon reduction due to increased adsorption and precipitation capacity of their reduced states. The fate of each element will depend on the kinetics and thermodynamics of microbial and chemical processes within soils. By impeding the spread of contaminants in the environment, remediation strategies can focus on source areas thereby accelerating clean-up activities at reduced effort and cost. Moreover, enhancing our knowledge of redox processes will improve modeling efforts aimed at predicting the fate of contaminants in surface and subsurface environments. 

One of the most important elements in the remediation of existing waste sites is early detection and actiom As an example, the cost of cleanup at Stringfellow, California, increased from an estimated 3.4 million to 65 million because of pollutant dispersal during a decade of inaction after the first identification of the problem. The opportunities for innovative sampling strategies responsive to this need are discussed in the following section. 

Based on our experience with remedial actions and modifications of design in new construction we recommend the following strategy for making new buildings (slab on grade, ventilated crawl space or furnished basement) radon protective or radon safe in a cost-effective way ... 

Cleanup strategies for hydrocarbon-affected soil will most likely be the last issue to be mandated from a regulatory perspective and certainly the most difficult technically to address. This difficulty reflects the large, deep-seated volumes of residual hydrocarbon present, and the current lack of efficient, cost-effective methodologies for in situ remediation of residual hydrocarbons in low-permeability, fine-grained soils. 

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