Soil & Groundwater Remediation Flashcards
6 cards from real ETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Soil & Groundwater Remediation flashcards as text
What is the difference between LNAPL and DNAPL in groundwater contamination scenarios?
Answer: LNAPL floats on the water table; DNAPL sinks below it
Light Non-Aqueous Phase Liquids (LNAPLs) have densities less than water and float on the water table, while Dense Non-Aqueous Phase Liquids (DNAPLs) are denser than water and sink below it.
In groundwater monitoring, what is the purpose of a 'sentinel well' placed downgradient of a remediation system?
Answer: To detect contaminant migration beyond the treatment zone
Sentinel wells serve as early warning indicators to detect whether contamination is migrating past the capture zone of a pump-and-treat or containment system.
Which EPA guidance document provides the framework for evaluating risk at contaminated sites to establish cleanup levels protective of human health?
Answer: EPA Risk Assessment Guidance for Superfund (RAGS)
EPA's Risk Assessment Guidance for Superfund (RAGS) provides the standard framework for conducting baseline human health risk assessments that determine remediation goals at contaminated sites.
Enhanced bioremediation of chlorinated solvents often involves injecting an electron donor such as vegetable oil or molasses. What process does this stimulate?
Answer: Anaerobic reductive dechlorination
Electron donor injection creates anaerobic conditions that stimulate reductive dechlorination, in which microorganisms sequentially remove chlorine atoms from compounds like PCE and TCE.
What does the term 'plume diving' describe in a groundwater contamination scenario?
Answer: Contaminant sinking into deeper aquifer units due to density or recharge
Plume diving occurs when a dissolved contaminant plume is driven downward into deeper aquifer zones due to recharge events, density differences, or aquifer heterogeneity.
Which type of soil boring technique uses a hollow stem to advance through soil while simultaneously collecting continuous soil samples?
Answer: Hollow-Stem Auger (HSA)
Hollow-stem auger drilling advances a continuous-flight auger with a hollow center, allowing soil sample collection and well installation without removing the auger from the borehole.