A large body of literature related to environmental site investigations is described in this article. A narrative describing the type and changing scope of the literature is followed by a bibliography organized into six categories of interest to environmental site investigators.

This paper describes the results from the pilot-scale demonstration study performed to remediate chromium-contaminated soil by Cold Top ex situ vitrification. Demonstration tests were performed on soils from two sites, containing residue from two types of chromite-ore processing. The sites were selected by NJDEP under an ongoing program to clean up over 150 hexavalent-chromium-contaminated sites. The primary objective of this demonstration was to determine if the waste processed by the Cold Top vitrification system meet the Resource Conservation and Recovery Act (RCRA) definition of a nonhazardous waste based on leachable chromium content in the waste. The toxicity characteristic leaching procedure (TCLP) was performed on both treated and untreated waste to evaluate if the Cold Top vitrified soils meet the above objective. Excavated soils from two sites were crushed, sieved, dried, and amended with carbon and sand and then shipped to a Cold Top vitrification plant. Cooled castings of the vitrified products were crushed and grounded for chemical analyses. The TCLP test results confirmed the effectiveness of the treatment. Analysis of operating costs indicated the Cold Top treatment cost of chromium-contaminated soil range from $80–207 depending on disposal costs and potential credit for sale of vitrified products.

Ethylenediaminetetraacetic acid (EDTA) is one of the more common chelating agents used in the extraction of heavy metals from soil. For soil extraction processes to be economically competitive with other remedial technologies, the amount of EDTA applied for extraction should be optimized; that is, extraction of metals should be maximized with a minimum amount of EDTA used. Generally, the molar amount of EDTA used is several times higher than the molar amount of the target metal present in the soil. This is to ensure there will be sufficient EDTA to extract the target heavy metals from the soil, since a host of non-target metals such as iron and calcium may compete for EDTA ligand sites. Bench-scale experiments using artificially prepared lead-contaminated soils were conducted to investigate the effects of amorphous iron and the different types of lead species on lead extraction. Three different lead species—lead sulfate, lead carbonate, and lead phosphate—were used. The extraction efficiency of lead was found to be a function of EDTA:Pb molar ratio, pH, lead species, and amorphous iron concentration. Experimental results showed that for a pH less than 6.0, amorphous iron in soil was found to strongly compete with lead for EDTA ligand sites. The extent of competition was dependent not only on the solution pH but also on the lead species present and the EDTA:Pb molar ratio. Amorphous iron was found to affect lead sulfate-contaminated soil the most, while lead carbonate-contaminated soil was the least affected. For EDTA:Pb molar ratios of less than 2, a solution pH between 6.5 and 8.5 must be maintained to optimize extraction of lead from lead sulfate- and lead phosphate-contaminated soil, if amorphous iron is present. The degree of difficulty of extraction of various lead species using EDTA:Pb molar ratios of less than 2 and in the presence of amorphous iron was: lead sulfate > lead phosphate > lead carbonate.

Pneumatic fracturing is a new enhancement process that has been accepted and recognized as a cost-effective technology in removing contaminants from polluted sites. This paper presents an engineering reliability assessment method for mass removal by the pneumatic fracturing process. An analysis was performed of mass removal with respect to four controlling input parameters, including diffusion coefficient, retardation factor, fracture aperture, and flow rate, each of which is stochastic in nature. The reliability index ratios were found to be greater than unity for each input parameter. From a site-remediation standpoint, the analysis reveals the physical significance of the four parameters in the pneumatic fracturing process. The tortuosity and retardation factor probability distributions have important impacts on the mass removal rate. The dimension of fracture aperture shows a limited direct influence on the mass removal with an independent flow rate input. Mass removal is sensitive to flow rate for relatively low flow range. The method described herein is a first attempt in reliability assessment of contaminant removal by pneumatic fracturing. Its approach can be further applied to other remediation operations.

The solubility of arsenic solids is of importance in public health, water treatment, and geochemistry. This work focuses on copper-arsenic and barium-arsenic solids. Experiments were conducted at conditions typical of water distribution systems (e.g., pH ∼ 7, T = 20°C, μ ∼ 10^−2.8 M, and typical elemental concentrations). The solubility product for barium hydrogen arsenate (BaHAsO₄) was verified by both precipitation and dissolution experiments as a log K_sp value of −5.51 ± 0.02, consistent with literature values. Evidence collected in systems with copper were not consistent with a single arsenic containing solid. Instead data appeared to favor sorption mechanisms with removed arsenic:copper ratios at 0.3:1. The results allow for improved predictability of arsenic behavior in manmade and natural systems.

Nitrate pollution of ground water is a serious problem in many areas of the United States. One source of nitrate contamination is municipal wastewater effluent. The practice of reusing treated sewage effluent is becoming more prevalent due to limited municipal water supplies. In this study, the discharge and end use of treated effluent in the Phoenix, Ariz., metropolitan area in 1997 were investigated. It was determined that 78% of the total nitrogen in treated wastewater effluent was retained in the local watershed, and 22% was exported from the area in the Gila River. Investigation into the end use of this effluent indicates that increased nitrate contamination of ground water may result from reusing wastewater.