CEA Soil Contamination Assessment 4

Question 1

Which quality assurance sample is used to detect potential cross-contamination between soil samples during field collection?

Accepted Answer

Equipment rinsate blank

Answer

Field blank

Answer

Trip blank

Answer

Matrix spike duplicate

Question 2

In soil contamination assessment, what is the primary purpose of a 'conceptual site model' (CSM)?

Accepted Answer

To summarize known and potential sources, pathways, and receptors in an integrated framework

Answer

To generate a 3D computer simulation of subsurface geology

Answer

To calculate the volume of contaminated soil requiring excavation

Answer

To satisfy OSHA requirements for site health and safety planning

Question 3

Which soil sampling method provides the LEAST disturbance to sample stratigraphy and is preferred for lithological logging?

Accepted Answer

Shelby tube (thin-walled tube) sampling

Answer

Grab sampling with a hand auger

Answer

Split-spoon sampling with standard penetration test (SPT)

Answer

Bulk bag sampling from stockpiled soil

Question 4

Under RCRA, which characteristic makes a contaminated soil a hazardous waste subject to full subtitle C management requirements?

Accepted Answer

Soil exhibits ignitability, corrosivity, reactivity, or toxicity as defined in 40 CFR Part 261

Answer

Total petroleum hydrocarbon concentration exceeds 500 mg/kg

Answer

Soil is listed in 40 CFR Part 261 Subpart D as a listed hazardous waste

Answer

Soil contains any detectable amount of a regulated contaminant

Question 5

What role does the 'vadose zone' play in soil contamination assessment?

Accepted Answer

It is the unsaturated zone between the land surface and the water table, through which contaminants migrate to groundwater

Answer

It represents the fully saturated zone below the water table where groundwater flows

Answer

It is the zone of capillary fringe saturation directly above the water table only

Answer

It refers to bedrock formations below the saturated zone

Question 6

Which statistical approach is most appropriate for determining whether site soil concentrations are significantly elevated above background?

Accepted Answer

Two-sample t-test or Wilcoxon rank-sum test comparing site and background data sets

Answer

Simple arithmetic mean comparison

Answer

Linear regression of concentration versus depth

Answer

Chi-square test of sample distribution

Question 7

For a carcinogenic contaminant in soil, the risk characterization step of a human health risk assessment calculates:

Accepted Answer

Excess lifetime cancer risk (ELCR) by multiplying chronic daily intake by the cancer slope factor

Answer

Hazard quotient (HQ) by dividing exposure dose by the reference dose (RfD)

Answer

Benchmark dose lower confidence limit (BMDL) from dose-response data

Answer

Lethal concentration (LC50) from acute toxicity tests