Soil Contamination Assessment 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 Soil Contamination Assessment flashcards as text
Which quality assurance sample is used to detect potential cross-contamination between soil samples during field collection?
Answer: Equipment rinsate blank
Equipment rinsate (decontamination) blanks are collected by rinsing clean water through decontaminated sampling equipment to verify that cleaning was effective and no cross-contamination occurred.
In soil contamination assessment, what is the primary purpose of a 'conceptual site model' (CSM)?
Answer: To summarize known and potential sources, pathways, and receptors in an integrated framework
A CSM integrates known and hypothesized sources, migration pathways, and potential receptors to guide site assessment and risk management decisions.
Which soil sampling method provides the LEAST disturbance to sample stratigraphy and is preferred for lithological logging?
Answer: Shelby tube (thin-walled tube) sampling
Shelby tube samplers recover relatively undisturbed cores that preserve stratigraphy, making them preferable for detailed lithological and stratigraphic logging.
Under RCRA, which characteristic makes a contaminated soil a hazardous waste subject to full subtitle C management requirements?
Answer: Soil exhibits ignitability, corrosivity, reactivity, or toxicity as defined in 40 CFR Part 261
Under RCRA, a solid waste is hazardous if it exhibits one of four characteristics—ignitability, corrosivity, reactivity, or toxicity—as defined in 40 CFR Part 261 Subparts C and D.
What role does the 'vadose zone' play in soil contamination assessment?
Answer: It is the unsaturated zone between the land surface and the water table, through which contaminants migrate to groundwater
The vadose zone is the unsaturated region between the land surface and the water table; it is a critical pathway through which contaminants migrate downward to groundwater.
Which statistical approach is most appropriate for determining whether site soil concentrations are significantly elevated above background?
Answer: Two-sample t-test or Wilcoxon rank-sum test comparing site and background data sets
A two-sample t-test (for normal data) or Wilcoxon rank-sum test (for non-normal data) is used to determine whether site concentrations are statistically distinguishable from background.
For a carcinogenic contaminant in soil, the risk characterization step of a human health risk assessment calculates:
Answer: Excess lifetime cancer risk (ELCR) by multiplying chronic daily intake by the cancer slope factor
Excess lifetime cancer risk (ELCR) is calculated by multiplying the chronic daily intake (CDI) by the chemical's cancer slope factor (CSF), expressing the incremental probability of developing cancer.