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API Publ 4715-2002 pdf free download

API Publ 4715-2002 pdf free download.Evaluating Hydrocarbon Removal from Source Zones and its Effect on Dissolved Plume Longevity and Magnitude.
The presence of multiple phases (water, LNAPL, vapor) in porous material influences the movement and transport of each phase under ambient or remediated conditions. Multiphase fluid mechanics and other principles are used to estimate the pore fluid fractions and their mobility under a variety of conditions. The distribution and composition of the LNAPL then determines the equilibrium chemi- cal partitioning into groundwater and vapor. Ultimately, the application of these principles results in estimates of the time dependent concentration of soluble components partitioning out of the LNAPL and into groundwater, with a link to vapor flux under ambient flow and partitioning conditions. For instance, one could look at chemical partitioning from an LNAPL source that has had no remediation action, or one could consider the same source after some cleanup effort (but not during that effort). This toolkit does not directly consider institutional controls, such as plume containment, that are often an important component of risk management. However, one could use the toolkit to consider the time frame over which an institutional control might be appropriate. Chemical concentration is the metric of this toolkit. All other things being equal, risk is proportional to the chemical concentration reaching receptors. Therefore, one can evaluate the risk/benefit of various LNAPL remediation strategies by looking at the concentration reduction associated with remediation. Specific site risk must be calculated separately by the user, as risk depends not only on the concentra- tions reaching the receptors, but also other factors in the exposure scenario, including the receptor characteristics, current and future land use, and other factors that are not part of this work. In developing this multiphase approach, several observations and conclusions have been reached regarding the importance of LNAPL distribution, its chemical character, and source remediation.
Effect of LNAPL Thickness The mass distribution of LNAPL and the related source longevity for any compound of interest are exponentially related to soil and fluid capillary properties, and to capillary pressure, which can, in turn, be related to the LNAPL thickness observed in a monitoring well at vertical equilibrium (VEQ). For a range of thicknesses from 0.25 to 2.0 meters in a fine-sand, the volume varies over nearly two orders of magnitude (Figure E-3). This has a very large impact on the chemical component depletion from the LNAPL under natural groundwater flow conditions (Figure E-4). Effect of LNAPL Residual Saturation LNAPL residual saturation is the smallest satura- tion remaining in the formation against applied hydraulic recovery and is the theoretical endpoint of LNAPL hydraulic recovery. It is also a highly optimistic endpoint because real hydraulic variability, well efficiency, well interference, aquifer heterogeneity and other factors all combine to diminish actual recovery and leave more LNAPL in the formation.
Contrast in Components of Concern The effective solubility and mole fractions of the various compounds in fuels have a signifi- cant effect on the longevity of the compounds within the source. For example, we have compared MTBE and benzene in gasoline with naphthalene in a diesel for 2 m of observed thickness in a fine-sand (Figure E-6). Because the effective solubility of MTBE and benzene are high relative to naphthalene, the source longevity between the components is separated by several orders of magnitude, with naphtha- lene present for tens of thousands of years for the conditions considered (Figure E-7).

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