Environmental Assessment & Sampling Techniques Flashcards
7 cards from real CEA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Environmental Assessment & Sampling Techniques flashcards as text
During low-flow groundwater sampling, which stabilization criteria must be met before collecting a sample?
Answer: pH ±0.5, specific conductance ±5%, DO ±10%, ORP ±10 mV across three readings
Low-flow sampling requires stabilization of field parameters (pH ±0.5 units, SC ±5%, DO ±10%, ORP ±10 mV) across three consecutive readings before sample collection.
Which type of environmental sampling error occurs when the sample collected does not represent the true population due to a flaw in sampling design?
Answer: Sampling bias from non-representative location selection
Sampling bias occurs when the sampling design systematically favors certain portions of the population, resulting in samples that do not accurately represent site conditions.
A site investigation requires characterizing contamination at depths ranging from 15 to 60 feet below ground surface in unconsolidated sediments. Which direct push technology is most commonly used?
Answer: Cone Penetrometer Testing (CPT) with chemical sensors
Cone Penetrometer Testing (CPT) with chemical sensors provides continuous subsurface profiling for contaminant characterization at depth in unconsolidated sediments without generating significant cuttings waste.
When assessing indoor air quality for vapor intrusion from groundwater contamination, which approach provides the most site-specific exposure assessment?
Answer: Collecting simultaneous sub-slab soil gas and indoor air samples
Simultaneous sub-slab soil gas and indoor air sampling provides the most defensible site-specific vapor intrusion assessment by measuring actual conditions rather than relying on default model assumptions.
A Phase I ESA report identifies a prior underground storage tank (UST) that was removed in 1989 with no closure documentation. How should this be classified?
Answer: Recognized Environmental Condition (REC) warranting Phase II investigation
A UST removal without documented closure confirmation or soil/groundwater sampling represents a REC because there is no evidence the removal was completed without a release.
Which EPA method is the standard for determining volatile organic compounds (VOCs) in groundwater samples submitted to a laboratory?
Answer: EPA Method 8260C (VOCs by purge-and-trap GC/MS)
EPA Method 8260C uses purge-and-trap concentration followed by GC/MS analysis and is the standard method for determining volatile organic compounds in aqueous and solid samples.
During a Preliminary Assessment under CERCLA, what is the primary source of information used to evaluate potential releases?
Answer: Existing records, databases, and file reviews without field sampling
A CERCLA Preliminary Assessment is a records review that uses existing information including federal and state databases, historical records, and file reviews to identify potential releases without field sampling.