Hence, an alternative technology, such as natural source zone depletion (NSZD), should be evaluated in lieu of passive skimmer methods. It should be noted, however, that skimming methods don't recover a substantial volume of LNAPL and LNAPL generally is not migrating at times when passive skimming technologies are used. Similar to hand bailing, passive skimmers generally are used to recover LNAPL when little LNAPL remains at a site. Passive skimming techniques are designed to remove LNAPL as it flows naturally (without pumping) into a recovery well or trench.Bailing can be performed daily, weekly, or monthly an appropriate frequency is determined based on the time it takes for the well to recharge as well as any applicable regulatory requirements/agreements.įree product skimming can be accomplished in a variety of methods that can be categorized as active skimming and passive skimming, described as follows: A check valve at the bottom of the bailer allows LNAPL (and some water) to enter, but prevents the fluids from exiting as the bailer is raised from the well. Bailing is performed using either a reusable or disposal bailer that is lowered into the well to remove remaining LNAPL from the well casing. It may be performed after a more aggressive (and costly) recovery technology has been implemented. Hand bailing generally is performed when there is little LNAPL remaining at the site as evidenced by relatively thin but measurable LNAPL thicknesses in one or more wells. Other Technology Namesįree product recovery systems in order of increasing complexity and cost include the following: The objective of these recovery techniques is to remove light nonaqueous phase liquid (LNAPL) to the extent practicable, prevent its migration and reduce its impact to dissolved phase contaminants in groundwater.
#Astm treatment well drawdown free#
Single and Dual Pump Free Product Recovery Technologiesįree product recovery consists of several technologies ranging from simple hand bailers and passive skimmer systems to more complex active skimming systems and large-scale total fluids recovery systems. Skimming Free Product Recovery Technologies This information may be reproduced without restriction as long as the source attribution is included.
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