Contaminants migration control

Extraction wells are usually necessary to maintain hydraulic control of the plume and to ensure that the plume does not migrate into clean areas or accelerate migration toward sensitive receptors. Placement of extraction wells is especially important with systems that use nutrient injection wells or infiltration galleries. These sources of fluids can alter natural groundwater flow patterns, which may cause contaminant migration in an unintended direction or rate. If the natural groundwater system has a sufficient concentration of electron acceptors and nutrients, to achieve remediation at an acceptable rate, it may not be necessary to add any additional materials. 

System controls surrounding water table, reducing off-site contaminant migration. 

Subsurface contaminant migration is controlled primarily by the flow field, the properties of the contaniinant(s) and the attenuation characteristics of the host rock involved. 

The implications of these electrolysis reactions are enormous in that they impact transport, transformation, and degradation processes that control the contaminant migration, removal, and degradation during electrochemical treatment. The different transport, transfer, and transformation processes induced by the applied electric field and how these processes are impacted by the electrolysis reactions at the electrodes are fundamental to the understanding of the electrochemical remediation technologies and are briefly presented in this section. 

TSR selection Criterion 1 is not considered applicable for the HCF. HCF ventilation system differential pressure instrumentation functions primarily to monitor control of radioactive contamination migration across confinement barrier boundaries. Although this instrumentation provides a positive indication of Zone 1 and Zone 2A canyon confinement barrier integrity, the absence of the appropriate differential pressure gradient does not necessarily indicate a significant degradation of a confinement barrier. Therefore, application of a Limiting Condition for Operation to this instrumentation is not warranted. 

Advection and dispersion of contaminants can be modeled using analytical and numerical methods. Advancement of computer technology now permits the use of complex numerical computational methods on portable computers. Modeling is helpful in evaluating factors that control contaminant migration, assessing the extent of contamination, and evaluating the effectiveness of remedial measures. 

Passive perimeter gas control systems are designed to alter the path of contaminant flow through the use of trenches or wells, and typically include synthetic flexible membrane liners (FMLs) and/or natural clays as containment materials. The membrane is held in place by a backfilled trench, the depth of which is determined by the distance to a limiting structure, such as groundwater or bedrock. A permeable trench installation functions to direct lateral migration to the surface, where the gases can be vented (if acceptable) or collected and conveyed to a treatment system (Figure 10a and 10b). 

Site H was the only site at which the contractor had implemented comprehensive and effective site control elements. The Site H contractor had established site work zones, a buddy system, and site communication procedures consistent with 1910.120(d). This contractor had also established exclusion zones and contamination reduction zones to control migration of site contaminants to clean areas of the site when work within these areas introduced the potential for exposure to hazardous contaminants. The audit team supported this contractor s use of flexible and temporary work zone boundaries based on monitoring results and hazard determinations. 

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