CSC Remediation & Mitigation Strategies 3 — Questions and Answers
Question 1: Which remediation technology applies heat to contaminated soil to volatilize and destroy organic contaminants without excavating the material?
- In-situ thermal treatment (ISTT) (Correct answer)
- Permeable reactive barrier (PRB)
- Bioventing
- Slurry wall containment
Correct answer: In-situ thermal treatment (ISTT)
ISTT techniques such as electrical resistance heating or steam injection heat subsurface soils in place to volatilize and destroy organic contaminants.
Question 2: A remediation contractor proposes a permeable reactive barrier (PRB) filled with zero-valent iron (ZVI). What is the primary contaminant target for ZVI PRBs?
- Petroleum hydrocarbons in surface soils
- Chlorinated solvents in groundwater (Correct answer)
- Nitrates in agricultural runoff
- Lead in urban dust
Correct answer: Chlorinated solvents in groundwater
ZVI in PRBs chemically reduces chlorinated solvents like TCE to less harmful compounds (ethene) as groundwater passively flows through the barrier.
Question 3: Under the CERCLA framework in the US, which document formally presents the selected cleanup remedy for a Superfund site?
- Remedial Investigation (RI) report
- Record of Decision (ROD) (Correct answer)
- Feasibility Study (FS) summary
- Environmental Impact Statement (EIS)
Correct answer: Record of Decision (ROD)
The Record of Decision (ROD) is the official US EPA document that describes and justifies the selected cleanup remedy for a Superfund site.
Question 4: A sustainability consultant recommends green infrastructure to mitigate urban heat islands. Which combination of strategies is most effective?
- Increasing impervious surfaces and installing white roofs only
- Planting urban trees, installing green roofs, and using cool pavements (Correct answer)
- Installing more air conditioning units city-wide
- Expanding parking lots with reflective coatings
Correct answer: Planting urban trees, installing green roofs, and using cool pavements
Combining urban trees, green roofs, and cool pavements addresses urban heat islands through shading, evapotranspiration, and increased surface albedo.
Question 5: What is the primary purpose of institutional controls (ICs) in a contaminated site cleanup?
- Physically remove all contamination to below detection limits
- Restrict land use and prevent exposure to residual contamination (Correct answer)
- Accelerate natural degradation of contaminants
- Require perpetual active treatment of the site
Correct answer: Restrict land use and prevent exposure to residual contamination
Institutional controls such as deed restrictions and land use covenants limit activities that could expose people to residual contamination left in place.
Question 6: A mining company must mitigate acid mine drainage (AMD). Which passive treatment system is most commonly used for AMD with moderate metal loads?
- Activated carbon filtration
- Successive alkalinity-producing systems (SAPS) (Correct answer)
- Reverse osmosis membranes
- UV disinfection reactors
Correct answer: Successive alkalinity-producing systems (SAPS)
SAPS combine organic compost and crushed limestone to passively generate alkalinity and precipitate metals from AMD with moderate contamination levels.
Question 7: Which approach best represents 'climate-proofing' infrastructure as a mitigation and adaptation strategy?
- Designing infrastructure to current climate norms only
- Incorporating projected future climate conditions into design standards (Correct answer)
- Using the cheapest available materials to allow frequent replacement
- Avoiding infrastructure investment in climate-sensitive areas entirely
Correct answer: Incorporating projected future climate conditions into design standards
Climate-proofing integrates projected changes in temperature, precipitation, and extreme events into design criteria so infrastructure remains functional under future conditions.
CSC Remediation & Mitigation Strategies 3
Which remediation technology applies heat to contaminated soil to volatilize and destroy organic contaminants without excavating the material?