Hydrogeologic setting

FIGURE 12.25 Subsurface hydrogeologic setting beneath major petroleum-handling facilities situated within the Central and West Coast Basins, southern California. (After Testa, 1992.) 

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The technical differences between site problems at RCRA facilities and CERCLA sites sometimes may be difficult to distinguish, owing to similarities in present or past uses of the site, in hydrogeologic setting, and/or in the types of substances disposed, spilled, or otherwise managed at the site. Consequently, many technical aspects of the study and remediation of releases of hazardous wastes and constituents from RCRA facilities often will closely parallel those at Superfund sites, and cleanups under both statutes must achieve similar goals for protection of public health and the environment. Additionally, activities which would be termed removal actions or expedited response actions under CERCLA may be undertaken by owners and operators under RCRA. In the RCRA context, such actions are termed interim measures, as will be discussed in subsequent chapters. 

A more in-depth discussion of the subsurface hydrogeologic setting, areal extent of LNAPL and dissolved hydrocarbons in groundwater, remedial strategy, and current status is presented in Chapter 12 (LNAPL Recovery Case Histories). 

The formation of substantial evaporite deposits requires two conditions (1) some mechanism by which salt ion concentrations are kept at supersaturated levels, and (2) a steady resupply of salt ions. The hydrogeologic setting that is most likely to meet these two criteria are shallow-water embayments located in arid climates where sea level is relatively stable and terrestrial runoff is very low or absent. 

Ravenscroft, P., Burgess, W.G., Ahmed, K.M. et al. (2005) Arsenic in groundwater of the Bengal Basin, Bangladesh Distribution, field relations, and hydrogeological setting. Hydrogeology Journal, 13(5-6), 727-51. 

A newly installed, i.e. a greatly stressed well, must stabilize for at least 24 hours after it has been developed in order to produce a representative sample in certain hydrogeological settings, stabilization time for new wells may exceed a week. After the well fills with fresh formation water, samples must be retrieved with a minimum exposure to air, with the least amount of resuspended sediment, and in a manner that prevents degassing. 

In 1996, Puls and Barcelona (1996) published a US EPA—GroundWater Issue to provide background information on the development of low-flow sampling procedures and its application under a variety of hydrogeological settings. 

Spruill, T. B. (2004). Effectiveness of riparian buffers in controfling ground-water discharge of nitrate to streams in selected hydrogeologic settings of the North Carolina Coastal Plain. Water Science ... 

Aller, L. Bennett, T. Lehr, J Petty, R. "DRASTIC A Standardized System for Evaluating Groundwater Pollution Potential using Hydrogeologic Settings" USEPA, Office of Research and Development Washington, D.C., 1985 384 pp. 

DRASTIC A System to Evaluate the Pollution Potential of Hydrogeologic Settings by Pesticides... 

This paper presents a standardized system which can be used to evaluate the ground-water pollution potential of any hydrogeologic setting in the United States. The system has been designed to use information which is available through a variety... 

Because pollution potential cannot be determined on a regional scale, smaller "hydrogeologic settings" were developed within each of the regions described by Heath (5). These hydrogeologic settings create units which are mappable and, at the same time, permit further delineation of the factors which affect pollution potential. 

Inherent in each hydrogeologic setting are the physical characteristics which affect the ground-water pollution potential. Many different biological, physical and chemical mechanisms may actively affect the attenuation of a contaminant and, thus, the pollution potential of that system. Because it is neither practical nor feasible to obtain quantitative evaluations of intrinsic mechanisms from a regional perspective, it is necessary to look at the broader parameters which incorporate the many processes. After a complete evaluation of many characteristics and the mappability of the data, the most important mappable factors that control the ground-water pollution potential were determined to be ... 

This system allows the user to determine a numerical value for any hydrogeologic setting by using an additive model. The equation for determining the DRASTIC Index is ... 

A Standardized System for Evaluating Ground Water Pollution Potential Using Hydrogeologic Settings" USEPA No. 600/2-85/... 

This paper will discuss the various means of dispersal of compounds disposed in a waste area located in a region of diverse hydrogeological setting. 

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