CEA Remediation Technologies 4

Question 1

Dual-phase extraction (DPE) simultaneously removes which two phases from the subsurface?

Accepted Answer

Soil vapor and groundwater (or NAPL)

Answer

DPE uses a high-vacuum system to extract both soil vapor from the vadose zone and contaminated groundwater (or free-phase NAPL) from the saturated zone through a single extraction well.

Question 2

The primary distinction between LNAPL and DNAPL behavior in the subsurface is that DNAPLs:

Accepted Answer

Sink below the water table because their density exceeds that of water

Answer

DNAPLs (dense non-aqueous phase liquids) have specific gravity greater than 1.0, causing them to penetrate the water table and migrate downward until reaching an impermeable layer or residual saturation.

Question 3

Which amendment is most commonly injected to stimulate enhanced reductive dechlorination (ERD) of chlorinated ethenes?

Accepted Answer

Emulsified vegetable oil (EVO) as an electron donor

Answer

EVO provides a slow-release carbon substrate that sustains anaerobic conditions and electron donor supply, enabling dehalorespiring bacteria (like Dehalococcoides) to reductively dechlorinate PCE and TCE to ethene.

Question 4

Solidification/stabilization (S/S) technology treats contaminated material by:

Accepted Answer

Immobilizing contaminants within a solid matrix to reduce leachability and mobility

Answer

S/S uses binders (cement, lime, pozzolans) to physically encapsulate or chemically fix contaminants, reducing their solubility and preventing leaching rather than destroying them.

Question 5

A Treatability Study is conducted during CERCLA remediation to:

Accepted Answer

Evaluate the performance and cost-effectiveness of candidate remedial technologies before full-scale implementation

Answer

Treatability studies (bench-scale or pilot-scale) test how well specific technologies work for site-specific conditions, providing data to support technology selection in the Feasibility Study.

(CEA) Certified Environmental Auditor Practice Test

(CEA) Certified Environmental Auditor Practice Test

CEA Remediation Technologies 4