CES Soil Contamination & Remediation 3 — Questions and Answers
Question 1: During a Phase II Environmental Site Assessment, which activity is typically performed?
- Review of historical aerial photographs and Sanborn maps
- Collection of soil and groundwater samples for laboratory analysis (Correct answer)
- Interviews with current and former property owners
- Review of regulatory agency database records
Correct answer: Collection of soil and groundwater samples for laboratory analysis
Phase II ESAs involve intrusive investigation — collecting and analyzing environmental samples (soil, groundwater, soil gas) to confirm or characterize contamination identified or suspected in Phase I.
Question 2: Polychlorinated biphenyls (PCBs) persist in soil primarily because they:
- React rapidly with soil minerals to form stable precipitates
- Are highly volatile and escape before degrading
- Are hydrophobic and strongly sorb to soil organic matter, resisting biodegradation (Correct answer)
- Are preferentially taken up by plants, removing them from soil
Correct answer: Are hydrophobic and strongly sorb to soil organic matter, resisting biodegradation
PCBs are highly hydrophobic compounds that partition strongly onto soil organic matter and are resistant to microbial degradation, resulting in long environmental persistence.
Question 3: In situ chemical oxidation (ISCO) using potassium permanganate is LEAST effective for treating which contaminant class?
- Chlorinated ethenes (e.g., TCE, PCE)
- BTEX compounds
- Saturated chlorinated alkanes (e.g., TCA) (Correct answer)
- Polycyclic aromatic hydrocarbons (PAHs)
Correct answer: Saturated chlorinated alkanes (e.g., TCA)
Potassium permanganate effectively oxidizes compounds with carbon-carbon double bonds (alkenes, aromatics) but reacts poorly with saturated chlorinated alkanes such as 1,1,1-TCA.
Question 4: Which of the following describes a Dense Non-Aqueous Phase Liquid (DNAPL)?
- A petroleum hydrocarbon lighter than water that floats on the water table
- A chlorinated solvent denser than water that sinks through the saturated zone (Correct answer)
- A dissolved contaminant plume migrating horizontally with groundwater
- An emulsified contaminant mixture held in soil micropores
Correct answer: A chlorinated solvent denser than water that sinks through the saturated zone
DNAPLs, such as PCE and TCE, are denser than water and sink vertically through the unsaturated and saturated zones until they reach an impermeable layer, making them difficult to locate and remediate.
Question 5: The concept of 'risk-based corrective action' (RBCA) for contaminated sites prioritizes:
- Complete removal of all detectable contamination regardless of cost
- Cleanup levels tied to site-specific exposure scenarios and acceptable risk levels (Correct answer)
- Excavation of contaminated soil as the default remedy
- Achieving background concentration levels for all contaminants
Correct answer: Cleanup levels tied to site-specific exposure scenarios and acceptable risk levels
RBCA establishes site-specific cleanup standards based on actual exposure pathways, receptor populations, and target risk levels rather than applying universal background or detection-limit-based standards.
Question 6: Which amendment to the Resource Conservation and Recovery Act (RCRA) addressed the cleanup of releases from underground storage tanks?
- Hazardous and Solid Waste Amendments (HSWA) of 1984 (Correct answer)
- Superfund Amendments and Reauthorization Act (SARA) of 1986
- Pollution Prevention Act of 1990
- Federal Facility Compliance Act of 1992
Correct answer: Hazardous and Solid Waste Amendments (HSWA) of 1984
The Hazardous and Solid Waste Amendments (HSWA) of 1984 added Subtitle I to RCRA, establishing the federal underground storage tank (UST) regulatory program including leak detection and corrective action requirements.
Question 7: Soil washing as a remediation technology works best when contaminants are:
- Covalently bound to silicate mineral lattices
- Associated with the fine-grained fraction of soil (silt and clay) (Correct answer)
- Uniformly distributed throughout the soil matrix
- Present as volatile organic compounds in the vadose zone
Correct answer: Associated with the fine-grained fraction of soil (silt and clay)
Soil washing exploits size segregation — contaminants preferentially associate with fine particles (silt, clay), so separating and treating the fine fraction concentrates the contamination and reduces the volume requiring disposal.
CES Soil Contamination & Remediation 3
During a Phase II Environmental Site Assessment, which activity is typically performed?