CES CES Remediation Technologies & Site Cleanup 2 — Questions and Answers
Question 1: What is the purpose of the 'Feasibility Study' (FS) in the CERCLA remediation process?
- To develop and evaluate alternative remediation approaches against CERCLA's nine evaluation criteria (Correct answer)
- To apportion financial cleanup responsibility among potentially responsible parties (PRPs)
- To assess worker health and safety risks during active site remediation operations
- To conduct the baseline ecological and human health risk assessment for the site
Correct answer: To develop and evaluate alternative remediation approaches against CERCLA's nine evaluation criteria
The Feasibility Study systematically develops and screens remediation alternatives against CERCLA's nine criteria—including protectiveness, implementability, and cost—to identify the preferred cleanup approach.
Question 2: What does 'treatment train' mean in the context of site remediation?
- Combining multiple complementary remediation technologies sequentially to address different contaminant conditions (Correct answer)
- A mobile treatment unit transported by rail to access remote contaminated sites
- The sequential series of regulatory approvals required before active remediation may begin
- The ranked order in which different contaminated environmental media must be treated
Correct answer: Combining multiple complementary remediation technologies sequentially to address different contaminant conditions
A treatment train integrates multiple technologies in sequence—such as ISCO to destroy source zone contamination followed by bioremediation to address the dissolved plume—when no single technology achieves cleanup goals.
Question 3: What is 'ex-situ thermal desorption' and how does it treat contaminated soil?
- Heating excavated soil to temperatures that volatilize organic contaminants, separating them from the soil matrix for off-gas treatment (Correct answer)
- Injecting steam into in-place soil to dissolve and mobilize semi-volatile contaminants for recovery
- Using microwave energy to destroy chlorinated organic compounds in extracted groundwater
- Combusting contaminated soil at high temperatures to completely destroy all organic contaminants
Correct answer: Heating excavated soil to temperatures that volatilize organic contaminants, separating them from the soil matrix for off-gas treatment
Ex-situ thermal desorption excavates contaminated soil and heats it to cause organic contaminants to volatilize and separate from the soil, with the generated vapors collected and treated—operating at lower temperatures than incineration.
Question 4: What is the primary performance metric for evaluating groundwater remediation system effectiveness over time?
- Contaminant concentration trends in performance monitoring wells (Correct answer)
- Total volume of groundwater extracted and processed by the treatment system
- Number of injection or extraction points installed across the site
- Per-gallon treatment cost compared to alternative remediation approaches
Correct answer: Contaminant concentration trends in performance monitoring wells
Declining contaminant concentration trends in monitoring wells are the primary indicator of whether a remediation system is achieving progress toward cleanup goals.
Question 5: What is an 'institutional control' in the context of contaminated site management?
- Legal or administrative mechanisms that restrict land use or exposure pathways at sites with residual contamination (Correct answer)
- A regulatory agency's enforcement authority to compel responsible parties to perform cleanup
- Financial assurance instruments such as bonds or trust funds for long-term site monitoring costs
- Permits and approvals required to operate active remediation equipment on a contaminated site
Correct answer: Legal or administrative mechanisms that restrict land use or exposure pathways at sites with residual contamination
Institutional controls are legal and administrative tools (e.g., deed restrictions, environmental easements, groundwater use restrictions) that limit exposure to residual contamination when engineering controls alone cannot achieve unrestricted cleanup levels.
Question 6: What is 'reductive dechlorination' in the anaerobic bioremediation of chlorinated solvents?
- Sequential anaerobic microbial removal of chlorine atoms from chlorinated solvents, ultimately producing harmless ethene (Correct answer)
- Chemical reduction of chlorinated compounds by zero-valent iron particles in a permeable reactive barrier
- Aerobic oxidation of chlorinated compounds by oxygenase-producing bacteria under aerobic conditions
- UV photolysis of chlorinated compounds in above-ground extracted groundwater treatment systems
Correct answer: Sequential anaerobic microbial removal of chlorine atoms from chlorinated solvents, ultimately producing harmless ethene
Reductive dechlorination is an anaerobic biological process where microorganisms (especially Dehalococcoides) sequentially remove chlorine atoms from PCE and TCE through a series of daughter products, ultimately yielding harmless ethene.
CES CES Remediation Technologies & Site Cleanup 2
What is the purpose of the 'Feasibility Study' (FS) in the CERCLA remediation process?