Site Remediation Flashcards

Which remediation technology uses microorganisms to degrade petroleum hydrocarbons in situ by injecting oxygen or nutrients into the subsurface?

Answer: Enhanced bioremediation

Enhanced bioremediation stimulates naturally occurring microorganisms by supplying oxygen, nutrients, or electron donors to accelerate biodegradation of contaminants in situ.

Under CERCLA, the National Contingency Plan (NCP) requires that remedies selected for Superfund sites meet what primary standard?

Answer: Applicable or relevant and appropriate requirements (ARARs)

NCP requires that Superfund remedies attain ARARs, which are federal and state environmental standards relevant to the site conditions.

A site has chlorinated solvent DNAPL contamination. Which technology directly targets the dense non-aqueous phase liquid source zone most effectively?

Answer: In situ chemical oxidation (ISCO)

ISCO delivers oxidants such as permanganate, persulfate, or hydrogen peroxide directly into the source zone to chemically destroy DNAPL-phase contaminants.

What term describes the process of documenting that a remediated site has achieved cleanup goals and no further action is required?

Answer: Site closure

Site closure is the formal regulatory process confirming cleanup objectives have been met, often resulting in a no-further-action (NFA) letter.

During a pump-and-treat operation, 'asymptotic tailing' refers to which phenomenon?

Answer: Contaminant concentrations leveling off at low but persistent levels

Asymptotic tailing occurs when dissolved contaminant concentrations drop steeply at first but then flatten at persistently low levels due to back-diffusion or NAPL dissolution.

Which vapor intrusion mitigation system depressurizes the sub-slab zone to prevent soil vapors from entering a building?

Answer: Sub-slab depressurization (SSD)

SSD installs suction pipes through the floor slab to maintain negative pressure beneath the building, diverting vapors away from interior spaces.

When excavating contaminated soil near a property boundary, which engineering control is most commonly used to prevent dust migration offsite?

Answer: Wind breaks and water misting systems

Water misting and wind breaks suppress fugitive dust during excavation operations, protecting neighboring receptors and complying with air quality requirements.