Subsurface contamination

Groundwater monitoring is a necessary component in any investigation of subsurface contamination. A wide variety of information can be gleaned from the data including groundwater velocity and direction, and contaminant identification and concentration. These data can be combined with other observations to infer various characteristics of the contamination. Examples are source and timing of the release, and future location of the contaminant plume. 

Nonaqueous phase Hquids (NAPLs) present special problems for soil and ground water cleanup. Contaminant transport through ground water depends in part on the water solubiHty of the compound. Because NAPLs cling to subsurface particles and are slow to dissolve in ground water, they hinder cleanups and prolong cleanup times. Dense nonaqueous phase Hquids (DNAPLs) migrate downward in the aquifer and can coUect in pools or pockets of the substmcture. Examples of DNAPLs are the common solvents tetrachloroethylene (PCE) and trichloroethylene (TCE) which were used extensively at many faciHties before the extent of subsurface contamination problems was realized. 

Nadeau, R., J. Lafornara, G. Klinger and T. Stone. Measuring Soil Vapors for Defining Subsurface Contaminated Plumes. Management of Uncontrolled Hazardous Waste Sites Proceedings, Hazardous Materials Control Research Institute, Washington, D.C., 1985. 

Subsurface contamination by organic chemicals is a widespread and serious problem, restricted not only to oil spills, but also pertinent in former and still-operating industrial sites. Remarkably, chemical-enhanced oil recovery technology can be used to remove oily contaminants from soil see Chapter 16, p. 232 for further explanation. 

C. Palmer, D.A. Sabatini and J.H. Harwell, In D.A. Sabatini and R.C. Knox (Eds.), Transport and Remediation of Subsurface Contaminants, ACS Symposium Series 491, American Chemical Society, Washington, DC, 1992. 

The impact from petroleum hydrocarbons and their derivatives in the environment can take many forms. Petroleum hydrocarbons in the form of fuels (i.e., gasoline, diesel, jet fuel, etc.) are very common subsurface contaminants. Their release into the environment is not necessarily well understood by the public at large. 

Testa, S. M., 1990, Light Non-Aqueous Phase Liquid Hydrocarbon Occurrence and Remediation Strategy, Los Angeles Coastal Plain, California In Proceedings of the International Association of Hydrogeologists, Canadian National Chapter, on Subsurface Contamination by Immiscible Fluids, April, in press. 

Adams, T. V. and Hampton, D. R., 1992, Effects of Capillarity on DNAPL Thickness in Wells and in Adjacent Sands In Proceedings of the I AH Conference on Subsurface Contamination by Immiscible Fluids, Balkema Publications, Rottendam. 

Weyer, K. U. (editor), 1992, Subsurface Contamination by Immiscible Fluids. International Association of Hydrogeologists, Canadian Chapter, A. A. Balkema, Rotterdam, the Netherlands, 576 pp. 

At Lawrence Livermore National Laboratory site 300, these compounds along with trichloroethylene (TCE) were used in heat-exchanger pipes at their materials testing facility [421-423]. Subsurface contamination by these compounds resulted from leaking heat-exchanger pipes. TBOS and TKEBS were present as light non-aqueous phase liquids whereas TCE was present as a dense... 

Under natural conditions, subsurface contaminants can be composed of single organic or inorganic compounds or mixtures thereof. These compounds have different properties, so they react differently, even if they reach the subsurface simultaneously. Therefore, knowledge of subsurface partitioning among individual components in a contaminant mixture is of major importance. 

Volatilization from mixtures of organic contaminants brings about changes in both the physical and the chemical properties of the residual liquid. We consider data on kerosene volatilization, as summarized in Yaron et al. (1998). Kerosene is an industrial petroleum product composed of more than 100 hydrocarbons, which may become a subsurface contaminant. 

Table 8.10 shows the concentration range of potential toxic trace elements in U.S. sewage sludges, as summarized by Chaney (1989). In this table, data on maximum concentration of toxic trace elements in dry, digested sewage sludges are compared to concentrations of the elements in median sludges and in soils. The subsurface contamination that may result from uncontrolled disposal on land surfaces... 

After reaching the subsurface, contaminants are partitioned among the solid, liquid, and gaseous phases. A fraction of the contaminated gaseous phase is transported into the atmosphere, while the remaining part may be adsorbed on the subsurface solid phase or dissolved into the subsurface water. Contaminants dissolved in the subsurface aqueous phase or retained on the subsurface solid phase are subjected, over the course of time, to chemical, biochemical, and surface-induced degradation, which also lead to formation of metabolites. 

Subsurface contamination by uranium wastes and contaminant speciation during transport from a wastewater pond (originating from a plutonium production plant) to groundwater were studied by Catalano et al. (2006). Land disposal of basic sodium aluminates and acidic U(VI)-Cn(ll) and their redistribution in the vadose zone resulted in development of a groundwater nraninm plume. The solid phase speciation of nraninm from the base of the pond, throngh the subsurface, to the... 

Transformation and reactions of contaminants in the subsurface are addressed in Part V. From an environmental point of view, we do not restrict the contaminant transformation to molecular changes we also consider the effects of such changes on contaminant behavior in the subsurface. Abiotic and biologically mediated reactions of contaminants in subsurface water are discussed in Chapter 13. Abiotic transformations of contaminants at the solid-liquid interface are described in Chapter 14, while biologically mediated changes in subsurface contaminants are the subject of Chapter 15. 

Environmental Remediation Consultants, Inc. (ERC) offers the BIO-INTEGRATION method for in sitn and ex situ destruction of organic compounds in soil, sediment, sludge, groundwater, snrface water, and wastewater. The BIO-INTEGRATION approach combines biotic and abiotic treatment methods to remediate subsurface contamination. On-site bioreactors are used to grow substrate- and contaminant-specific microbes. The microbes are combined with abiotic amendments and injected into the subsurface. 

According to the vendor, typical subsurface contaminant recovery applications cost about 75 to 150/yd. In contrast, costs for removal and incineration can range from 200 to 300/yd (D14453G, p. 5). 

Hugh Russell and Guy Sewell of the U.S. Environmental Protection Agency have investigated the application of reductive anaerobic biological in situ treatment (RABIT) to subsurface contamination in partnership with the Departments of Energy and Defense. This technology is still undergoing development and is not commercially available. 

Gorelick, S. M. (1990). Large scale nonlinear deterministic and stochastic optimization Formulations involving simulation of subsurface contamination. Mathematical Programming, 48, 19-39. 

The hydrophobic oils evaluated in phase behavior studies were diesel, dodecane, and hexadecane. A commercial Diesel was selected based on its occurrence as a subsurface contaminant and its hydrophobicity. Based on... 

Fountain, J.C., Field Tests of Surfactant Flooding in Transport and Remediation of Subsurface Contaminants, American Chemical Sotiety Washington, 1992, pp. 182-191. 

Subsurface Contaminants Focus Area Technology Summary, Rainbow Series, U.S. Department of Energy, Office of Science and Technology, August 1996 (Report No. DOE/EM-0296, NTIS Order No. DOE/EM-0296 available through EM Helpline Tel + 1-800-736-3282). 

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