CHMM Site Remediation 5 — Questions and Answers
Question 1: Under EPA's Superfund removal action authority, what is the maximum expenditure allowed for a standard removal action before a remedial action must be initiated?
- $1 million
- $2 million (Correct answer)
- $5 million
- $10 million
Correct answer: $2 million
CERCLA limits standard removal actions to $2 million and 12 months unless the EPA Administrator determines that additional action is necessary.
Question 2: Phytoremediation using plants to uptake and concentrate metals in above-ground biomass is specifically called what?
- Phytostabilization
- Phytoextraction (Correct answer)
- Rhizofiltration
- Phytodegradation
Correct answer: Phytoextraction
Phytoextraction uses hyperaccumulator plants to take up metals from soil into harvestable shoot tissue, which is then removed and disposed of to reduce soil metal concentrations.
Question 3: A remedy that relies on engineered containment (cap and barrier walls) with no active treatment is evaluated most critically under which NCP criterion?
- Short-term effectiveness
- Long-term effectiveness and permanence
- Reduction of toxicity, mobility, or volume through treatment (Correct answer)
- State acceptance
Correct answer: Reduction of toxicity, mobility, or volume through treatment
NCP favors treatment that permanently reduces contaminant hazards; containment-only remedies score lower on reduction of toxicity, mobility, or volume, requiring strong justification.
Question 4: Which type of groundwater model is most appropriate for predicting the long-term migration of a dissolved contaminant plume in a heterogeneous aquifer?
- Analytical model assuming homogeneous, isotropic conditions
- Numerical flow and transport model incorporating site-specific heterogeneity (Correct answer)
- Statistical regression model based on monitoring data alone
- Conceptual site model without quantitative predictions
Correct answer: Numerical flow and transport model incorporating site-specific heterogeneity
Numerical models discretize the aquifer into cells that can represent spatial variability in hydraulic conductivity and other parameters affecting contaminant transport.
Question 5: When evaluating the toxicity of a contaminant mixture at a Superfund site, EPA typically applies what approach to combine individual chemical risks?
- Risk multiplication
- Hazard quotient addition (hazard index) for non-carcinogens and risk addition for carcinogens (Correct answer)
- Using only the highest single-chemical risk
- Geometric mean of individual risks
Correct answer: Hazard quotient addition (hazard index) for non-carcinogens and risk addition for carcinogens
The hazard index sums individual hazard quotients for non-carcinogens, and individual cancer risks are summed for carcinogens, giving a cumulative mixture risk estimate.
Question 6: A brownfields site developer wants to reuse a former dry-cleaning facility for retail use. Which remediation approach most efficiently manages residual PCE contamination while allowing site redevelopment?
- Full excavation to background levels before any construction
- Risk-based closure with land use controls and long-term monitoring (Correct answer)
- Monitored natural attenuation with no institutional controls
- Pump and treat operated for 50 years before redevelopment
Correct answer: Risk-based closure with land use controls and long-term monitoring
Risk-based closure with institutional controls allows development to proceed while managing residual contamination through deed restrictions and monitoring, balancing protection with economic reuse.
Question 7: Which regulatory framework specifically governs the investigation and cleanup of releases from underground storage tanks (USTs) containing petroleum products?
- CERCLA Superfund program
- RCRA Subtitle I UST regulations (40 CFR Part 280) (Correct answer)
- TSCA Section 7 imminent hazard authority
- Clean Water Act SPCC rule
Correct answer: RCRA Subtitle I UST regulations (40 CFR Part 280)
RCRA Subtitle I and 40 CFR Part 280 establish the UST program, including release detection, corrective action, and closure requirements for petroleum UST systems.
CHMM Site Remediation 5
Under EPA's Superfund removal action authority, what is the maximum expenditure allowed for a standard removal action before a remedial action must be initiated?