Soil Contamination & Remediation Flashcards
7 cards from real CES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Soil Contamination & Remediation flashcards as text
Stabilization/solidification (S/S) as a soil remediation method primarily works by:
Answer: Reducing contaminant leachability and mobility by incorporating them into a solid matrix
S/S reduces contaminant bioavailability and leachability by physically encapsulating or chemically binding contaminants in a stable, low-permeability solid matrix such as Portland cement or pozzolanic binders.
Which isotope ratio analysis technique is used to distinguish petroleum hydrocarbon contamination from naturally occurring biogenic sources in soil?
Answer: Compound-specific isotope analysis (CSIA) of stable carbon isotopes
CSIA measures 13C/12C ratios in specific organic compounds; petroleum hydrocarbons have distinct isotopic signatures that differ from biogenic sources, enabling source differentiation.
At a former dry-cleaning facility, the primary contaminants of concern in soil and groundwater are most likely:
Answer: Tetrachloroethylene (PCE) and its degradation products
Dry-cleaning operations historically used PCE (perchloroethylene) as the primary solvent, making PCE and its reductive dechlorination products (TCE, DCE, VC) the expected contaminants of concern.
Which document formally defines the objectives, technical approach, schedule, and quality requirements for a soil remediation investigation?
Answer: Sampling and Analysis Plan (SAP)
The Sampling and Analysis Plan, comprising the Quality Assurance Project Plan (QAPP) and Field Sampling Plan (FSP), governs the technical and QA/QC requirements for environmental data collection activities.
The 'ten-to-the-negative-sixth' (10⁻⁶) risk level used in CERCLA risk assessment represents:
Answer: A one-in-a-million additional cancer risk over a 70-year lifetime
EPA's acceptable excess lifetime cancer risk range for Superfund sites is 10⁻⁶ to 10⁻⁴; 10⁻⁶ represents one additional cancer in one million people exposed over a 70-year lifetime and is the target risk level.
Which soil property most strongly influences the retardation factor of organic contaminants migrating through the unsaturated zone?
Answer: Fraction of organic carbon (foc) and the contaminant's Koc value
The retardation factor for organic contaminants is largely determined by sorption to soil organic matter, quantified by foc × Koc; higher values of either parameter cause greater retardation of contaminant migration.
Enhanced in situ bioremediation (EISB) of chlorinated solvents in groundwater most commonly involves:
Answer: Adding electron donors (e.g., emulsified vegetable oil) to stimulate anaerobic reductive dechlorination
EISB for chlorinated solvents typically injects electron donors such as emulsified vegetable oil, molasses, or lactate to create reducing conditions that promote microbial reductive dechlorination.