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Environmental Investigations
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Environmental subsurface investigations are very detailed scientific investigations. These investigations collect enormous amounts of geologic and hydrogeologic information and significant amounts of other information. All of this information allows the professionals conducting the investigation to determine the existence of contamination at a site or property and if the level of any contamination present requires a remedial action because it presents an unacceptable risk to human health or the environment. Environmental investigations must be conducted with a high level of scientific care for several reasons: (1) because contaminants requiring a remedial action may be present at very low levels and precautions must be taken to minimize the chances of any cross-contamination, (2) because the investigation and potential remediation must be conducted in such a manner to enable their admission in a court of law, and (3) to protect the investigators from any exposure to contaminants while collecting and handling samples taken during field activities. Over the last 25 years, environmental subsurface investigations have been the most common type of environmental investigation conducted. In urban areas, they have provided extensive geologic and hydrogeologic information of the highest quality. Therefore, environmental subsurface investigations can form the cornerstone of mapping the geology and hydrogeology of an urban watershed.
Nature and Extent of Hazardous Waste
Published in Barry L. Johnson, Impact of Hazardous Waste on Human Health, 2020
The ultimate environmental impact of the CERCLA statute is the remediation of uncontrolled hazardous waste sites. This action removes environmental contamination that can potentially cause adverse human health and ecologic effects. The actual cleanup of a site is the culmination of the Superfund remediation process. Remedial actions at a particular site may take years, depending on such factors as size of the site and the specific cleanup methods chosen. After remediation, NPL sites are removed from the NPL. According to the EPA, cleanup construction has been completed at 504 NPL sites and another 473 sites are in construction, as of January 1998. Moreover, the EPA states that more than 89% of nonfederal NPL sites are either undergoing cleanup construction (remedial or removal), or have been completed (Fields, 1998).
Mathematical Hydrocarbon Fate Modeling in Soil Systems
Published in Edward J. Calabrese, Paul T. Kostecki, Principles and Practices for Petroleum Contaminated Soils, 2019
Edward J. Calabrese, Paul T. Kostecki
With a soil system as an example, there are four major exposure pathways for contaminants at uncontrolled waste sites: leachate-groundwater, surface water, contaminated soil, and residual waste and air. The environmental setting for an uncontrolled waste site located above the water table is shown in Figure 124 and in Figure 2.25 The potential pathways to human and ecological receptors are depicted in Figure 3. A variation of the above would be a site where the waste was buried below the water table; in this case, the leachate plume and the groundwater are coincident. The exposure pathways are essentially the same in both cases. Remedial actions are designed to reduce exposure of both humans and the environment to acceptable levels either by containing pollutants originating from the site in place, or by removing the hazardous substances from the immediate environment.
A closer look at the locked-wheel pavement friction data in the ltpp database for selected states
Published in Cogent Engineering, 2019
Maher M. Murad, Khaled A. Abaza
Over forty states reported performing friction testing on a regular basis and using the results in their pavement management system. However, only eleven states indicated having intervention level for friction. The minimum pavement friction requirement varies among the states. The range for FN is 28 to 41 for interstates, 25 to 35 for primary roads, and 22 to 35 for secondary roads. The most common minimum FN reported is 35. A survey (Ksaibati, Cole, & Farrar, 1996) gave a wide range of FN requirements for directing attention to corrective rehabilitation from 20 in Virginia to 43 in Arizona. Another survey (NCHRP, 2000) indicated that eighteen states have investigatory FN levels with a mode of 40, and fifteen states have intervention FN levels with a mode of 30. Investigatory levels set by an agency call for site investigation to determine the need for remedial action while intervention levels require remedial action (National Cooperative Highway Research Program (NCHRP), 2009). Mayora and Pina (Mayora & Pina, 2009) reported that raising the FN value from 33 to 48 may result in a reduction in wet pavement accidents by as much as 60%. Micro-surfacing and resurfacing are examples of maintenance activities aimed at restoring pavement friction. Micro surfacing is generally considered to be effective for five to seven years, while resurfacing with the standard friction top course of 1.5 inches (3.8 cm) is expected to last fifteen years (Lyon & Persaud, 2008).