DEQ Soil and Land Contamination 3 — Questions and Answers
Question 1: What is 'in situ' remediation and why is it often preferred over 'ex situ' approaches?
- In situ means treating contamination after excavation and transport to a licensed treatment facility
- In situ means treating contamination in place without excavation, which reduces cost, site disturbance, and exposure risks during cleanup (Correct answer)
- In situ refers to biological remediation only, while ex situ refers to chemical treatment
- In situ remediation is a laboratory analysis technique, not an actual cleanup method
Correct answer: In situ means treating contamination in place without excavation, which reduces cost, site disturbance, and exposure risks during cleanup
In situ remediation treats contamination where it exists in the subsurface, avoiding costly and disruptive excavation while reducing worker exposure and transportation risks.
Question 2: What does a 'no further action' (NFA) letter from the DEQ signify?
- The DEQ has ceased all regulatory oversight because the site is too contaminated to clean up
- The DEQ has determined that cleanup is complete or that no cleanup is needed because the site does not pose unacceptable risk (Correct answer)
- The responsible party has been excused from cleanup due to financial hardship
- The site has been transferred to federal Superfund jurisdiction
Correct answer: The DEQ has determined that cleanup is complete or that no cleanup is needed because the site does not pose unacceptable risk
A NFA letter is a regulatory closure document indicating that the DEQ has reviewed the site and determined that no additional cleanup is required, providing liability relief to the property owner.
Question 3: What is the primary concern with chlorinated solvents like trichloroethylene (TCE) at contaminated sites?
- TCE is highly flammable and poses explosion risks during remediation
- TCE is a Dense Non-Aqueous Phase Liquid (DNAPL) that sinks below the water table and is a probable human carcinogen, making cleanup extremely difficult (Correct answer)
- TCE bonds permanently to soil particles and cannot be removed by any known remediation technology
- TCE contamination is only a concern at surface water levels, not in groundwater
Correct answer: TCE is a Dense Non-Aqueous Phase Liquid (DNAPL) that sinks below the water table and is a probable human carcinogen, making cleanup extremely difficult
Chlorinated solvents like TCE are DNAPLs that sink through aquifers and are classified as probable human carcinogens, making them among the most challenging and concerning groundwater contaminants to remediate.
Question 4: What is 'enhanced bioremediation' for contaminated soil and groundwater?
- Genetically engineering microorganisms to destroy contaminants more efficiently than native bacteria
- Stimulating naturally occurring microorganisms to degrade contaminants faster by adding nutrients, electron donors, or oxygen to the subsurface (Correct answer)
- Applying heat to increase microbial activity in cold climates during winter months
- Introducing non-native microorganisms from other contaminated sites where biodegradation was successful
Correct answer: Stimulating naturally occurring microorganisms to degrade contaminants faster by adding nutrients, electron donors, or oxygen to the subsurface
Enhanced bioremediation accelerates natural biodegradation by supplying amendments (nutrients, electron donors, or oxygen) that boost the activity of native microorganisms already degrading contaminants.
Question 5: What is the 'innocent landowner defense' under CERCLA and what must a property purchaser demonstrate to use it?
- The landowner must prove that they were unaware of contamination when they purchased the property, and they conducted all appropriate inquiry (AAI) before purchase (Correct answer)
- The landowner must demonstrate that contamination migrated from an adjacent property after they acquired the site
- The landowner must show that they reported the contamination to the DEQ within 24 hours of discovery
- The landowner must prove that the contamination predates the enactment of CERCLA in 1980
Correct answer: The landowner must prove that they were unaware of contamination when they purchased the property, and they conducted all appropriate inquiry (AAI) before purchase
The innocent landowner defense protects purchasers who conducted all appropriate inquiry (AAI) before purchasing and had no reason to know about contamination, shielding them from CERCLA liability.
Question 6: What is a 'remedial investigation/feasibility study' (RI/FS) in the Superfund cleanup process?
- A preliminary screening to determine whether a site qualifies for NPL listing
- A comprehensive site characterization (RI) followed by evaluation of cleanup alternatives (FS) to support selection of the final remedy (Correct answer)
- A financial assessment of how cleanup costs will be allocated among potentially responsible parties
- A regulatory process to determine whether state or federal agency will lead the cleanup
Correct answer: A comprehensive site characterization (RI) followed by evaluation of cleanup alternatives (FS) to support selection of the final remedy
The RI/FS is the core technical phase of Superfund cleanup—the RI characterizes site contamination and the FS evaluates cleanup alternatives against criteria like effectiveness, feasibility, and cost.
DEQ Soil and Land Contamination 3
What is 'in situ' remediation and why is it often preferred over 'ex situ' approaches?