Hazardous waste sites disposal

Hatch, J. and E. Hayes. "State-of-the-Art Remedial Action Technologies Used for the Sydney Mine Waste Disposal Site Cleanups," In Management of Uncontrolled Hazardous Waste Sites Proceedings, Washington, D.C., 1985, pp. 285. 

OSHA s Hazardous Waste Operations and Emergency Response (HAZWOPER) legislation protects workers who respond to emergencies, such as serious spills, involving hazardous materials. It also covers those employed in cleanup operations at uncontrolled hazardous waste sites and at EPA-licensed waste treatment, storage, and disposal facilities. 

Populations residing near hazardous waste disposal sites may be subject to higher levels of methyl parathion in environmental media (i.e., air, groundwater, soil) than those experienced by the general population. Methyl parathion has been identified in at least 16 of the 1,585 hazardous waste sites that have been proposed for inclusion on the EPA National Priorities List (NPL). However, the number of sites evaluated for methyl parathion is not known. As more sites are evaluated, the number of sites where methyl parathion has been detected may increase. 

In addition to individuals who are occupationally exposed to endosulfan (see Section 5.5), there are several groups within the general population that have potentially high exposures (higher than background levels) to endosulfan. These populations include individuals living in proximity to sites where endosulfan was produced or sites where endosulfan was disposed of, and individuals living near one of the 162 NPL hazardous waste sites where endosulfan has been detected in some environmental media (HazDat 2000). 

Production, Import/Export, Use, Release, and Disposal. Endosulfan is distributed in the environment as a result of its use as an insecticide (Gregor and Gummer 1989 NRCC 1975 Strachan et al. 1980). Humans may be exposed through the ingestion or use of contaminated food (Gartrell et al. 1986 Podrebarac 1984a) or tobacco products (EPA 1982a), contact with media from contaminated hazardous waste sites (principally soils), or insecticide apphcafion (Oudbier et al. 1974 Wolfe et al. 1972). 

With the recent Increase In activity at hazardous waste sites where cleanup and remedial action are underway, there has emerged a need for rapid analytical methods for assessing contamination in water, sediment, and soil. Of special Interest, because of widespread use and disposal. Is the group of materials known as PCB s (polychlorinated biphenyls). 

Organophosphate ester hydraulic fluid components have also been detected in groundwater near a hazardous waste site (1.7 pg/L tributyl phosphate) (Sawhney 1989) and in surface water from a radioactive waste disposal site (triphenyl phosphate and tributyl phosphate) (Francis et al. 1980). Organophosphate... 

Soil Cleanup, or remediation, of hazardous waste sites will often produce contaminated soil. Contaminated soil must be handled as hazardous waste if it contains a listed hazardous waste or if it exhibits a characteristic of hazardous waste. As with hazardous waste, land disposal of hazardous soil is prohibited until the soil has been treated to meet LDR standards. These contaminated soils, due to either their large volume or unique properties, are not always amenable to the waste codespecific treatment standards. Because of this, U.S. EPA promulgated alternative soil treatment standards in 268.49 in May 1998. The alternative soil treatment standards mandate reduction of hazardous constituents in the soil by 90% or 10 times UTS, whichever is higher. Removal of the characteristic is also required if the soil is ignitable, corrosive, or reactive. 

Chemical compatibility tests using U.S. EPA Method 909040 should always be performed for hazardous waste sites, but some municipal waste sites also contain hazardous, nondegradable materials. U.S. EPA conducted a 5-year study of the impact of municipal refuse on commercially available liner materials and found no evidence of deterioration within that period. However, in a current study of leachate quality in municipal landfills, the Agency has discovered some organic chemical constituents normally found in hazardous waste landfill facilities. Apparently, small quantities of household hazardous waste enter municipal sites or are disposed of as small quantity generator wastes. As a result of these findings, U.S. EPA developed a position on the need for chemical compatibility tests for thousands of municipal waste disposal sites. 

Exposure Levels in Humans. Hexachloroethane has not been detected in human tissues as a result of exposure to this chemical from environmental media. Biological monitoring data were not located for populations surrounding hazardous waste sites. Hexachloroethane has been detected in the plasma of workers at concentrations of 7.3 6 pg/L, despite the use of protective equipment including disposable overalls and compressed-air-fed visors or full-facepiece masks with filters (Selden et al. 1994). Because of protective equipment, exposure concentrations could not be related to plasma levels of hexachloroethane. 

Potentially Responsible Party (PRP) An individual or company identified by EPA as potentially liable under CERCLA for cleanup costs at a hazardous waste site. PRPs may include generators of hazardous substances, present or former owners of hazardous substances that have been disposed, site property owners, and transporters of hazardous materials to the site. 

At many waste sites, -hexane has been detected in the landfill gases vented from the soils at the disposal sites (Brosseau and Heitz 1994 O Leary and Walsh 1995). While information in the literature is extremely limited, trace levels of -hexane are probably found in the soils or the soil gases at many waste disposal sites. u-Hexane has been identified in the soil at 14 sites and in sediments at two sites among the 60 NPL hazardous waste sites where it was detected in some environmental medium (HazDat 1998). 

The main sources for potential human exposure to endrin are residues on imported food items, unused stocks, unregistered use, inappropriate disposal, and hazardous waste sites however, there is no current evidence of significant exposures from any of these sources. Furthermore, it should be noted that in environmental media, especially in contaminated soils and sediments, the amount of endrin chemically identified by analysis is not necessarily the amount that is toxicologically available. 

There is a potential for endrin to be present in soils and sediments at hazardous waste sites. Endrin has been detected in soil samples collected at 44 of the 102 NPL sites and in sediment samples collected at 19 of the 102 NPL sites where endrin has been detected in some environmental medium however, concentrations were not reported (HazDat 1996). Endrin was not detected (detection limit 0.01 ppm [10 ppb] wet weight), however, in soils derived from dredged materials at 9 confined disposal facilities bordering the Great Lakes (Beyer and Stafford 1993). 

Releases of thiocyanate to soil result from anthropogenic and natural sources. Anthropogenic releases occur primarily from direct application in herbicidal formulations (e.g., amitrol-T, a mixture of ammonium thiocyanate and amino-1,2,4-triazole) and from disposal as byproducts from industrial processes. Nonanthropogenic sources include damaged or decaying tissues of plants from the family Brassica (e.g., mustard, rape) (Brown and Morra 1993). Thiocyanate has been detected in soil samples collected at 2 of the 8 hazardous waste sites, and in sediment samples at 3 of the 8 hazardous waste sites where thiocyanate has been detected in some medium (HazDat 1996). The HazDat information used includes data from both NPL and other Superfund sites. 

Disulfoton enters the environment primarily during its use as an insecticide/acaricide in crops and vegetables, and in homes and gardens. Other important pathways for disulfoton s entry into the environment are the disposal of liquid disulfoton wastes into soil evaporation pits, ditches, ponds (Winterlin et al. 1989), and hazardous waste sites. Thus, soil is the environmental medium most likely to be contaminated with disulfoton. The processes that may transport disulfoton from soil to other environmental media include leaching to groundwater, runoff to surface water, and absorption by plants (Holden 1986 Mostaghimi et al. 1993 Nash 1974 Plumb 1991 Sanborn et al. 1977 ... 

Other than aerial application over swamps for mosquito abatement, disulfoton is not known to be used over water. Potential sources of release into surface water include discharge of waste water from disulfoton manufacturing, formulation, and packaging facilities (HSDB 1994). Leaching and runoff from treated fields, pesticide disposal pits, or hazardous waste sites may contaminate both groundwater and surface water with disulfoton. Entry into water can also occur from accidental spills. Small amounts of volatilized disulfoton may be removed from the atmosphere as a result of wet deposition and may enter surface water (Racke 1992). 

Release routes of 3,3 -dichlorobenzidine to the environment appear to be waste waters, sludges, and solid wastes where emissions are not properly controlled during the use of 3,3 -dichlorobenzidine or during its chemical transformation to pigments. The compound has been found in water and soil at hazardous waste sites, a result of the improper land disposal of solid wastes. 

Diehlorobenzidine has been identified in at least 32 of the 1,467 current or former EPA National Priorities List (NPL) hazardous wastes sites (HazDat 1998). However, the number of sites evaluated for 3,3 -diehlorobenzidine is not known. The frequeney of these sites within the United States can be seen in Figure 5-1. The manufacture and use of 3,3 -dichlorobenzidine has been strictly regulated by OSHA since 1974. All work with the compound is done in elosed systems and any residues are destroyed by chemical reaction. Such precautions, if conscientiously praetieed, make it unlikely that significant quantities of 3,3 -diehlorobenzidine have been disposed of in landfills or at NPL sites after 1974. 

Although these generalizations were not Intended to be applied to waste disposal sites, the generalizations likely have some relevance to uncontrolled hazardous waste sites, as long as the reader remembers the differences described In the beginning of the Chemical Characteristics section. 

The use of an acceptable (barely tolerable) risk to classify nonexempt waste can be justified, in part, on the following grounds. Disposal facilities for exempt and low-hazard waste both are located near the ground surface, and many scenarios for inadvertent intrusion into municipal/industrial landfills for nonhazardous waste also would be credible occurrences at disposal sites for low-hazard waste. However, these types of scenarios should be less likely to occur at hazardous waste sites, compared with sites for disposal of nonhazardous waste, given the intention to maintain institutional control and records of past disposal activities for a considerable period of time after closure of hazardous waste sites and the possibility that societal memory of disposal activities will be retained long after institutional control is relinquished. Thus, the risk to future inadvertent intruders at dedicated hazardous waste disposal sites, taking into account the probability that exposures according to postulated scenarios would actually occur, should be comparable to the risk at disposal sites for nonhazardous waste. 

In implementing the risk-based waste classification system developed in this Report, the selection of exposure scenarios appropriate to waste disposal is an important technical issue that must be addressed. NCRP believes that scenarios for inadvertent intrusion into near-surface disposal facilities are appropriate in classifying waste for purposes of disposal and, further, that scenarios involving permanent occupancy of disposal sites after loss of institutional control would be appropriate (see Section 6.1.3) such scenarios are commonly used in regulating near-surface disposal of low-level radioactive waste and in risk assessments at hazardous waste sites subject to remediation under CERCLA. 

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