CEA Environmental Assessment & Sampling Techniques 2 — Questions and Answers
Question 1: When conducting a Phase II Environmental Site Assessment, which QA/QC measure ensures laboratory results are representative of field conditions?
- Using field duplicates and trip blanks (Correct answer)
- Collecting only one sample per media
- Relying solely on visual inspection data
- Skipping chain-of-custody documentation
Correct answer: Using field duplicates and trip blanks
Field duplicates verify sampling reproducibility while trip blanks detect cross-contamination during transport, both are essential QA/QC measures in Phase II ESAs.
Question 2: Which soil sampling method is most appropriate for collecting a representative composite sample across a large, uniformly contaminated area?
- Judgmental sampling at suspected hot spots only
- Systematic grid sampling with equal-spaced intervals (Correct answer)
- Simple random sampling with no spatial pattern
- Grab sampling at a single central point
Correct answer: Systematic grid sampling with equal-spaced intervals
Systematic grid sampling provides equal spatial coverage across a site, making it the most appropriate method for characterizing uniform contamination in large areas.
Question 3: A NAPL (Non-Aqueous Phase Liquid) is identified in a monitoring well. What does the presence of LNAPL indicate?
- Contamination has migrated below the water table
- Product is floating on the water table surface (Correct answer)
- Dense contaminants have sunk to the aquifer bottom
- Groundwater flow has reversed direction
Correct answer: Product is floating on the water table surface
LNAPL (Light Non-Aqueous Phase Liquid) is less dense than water and floats at or near the water table surface, indicating a surface or shallow subsurface release.
Question 4: During air sampling for volatile organic compounds (VOCs) using Summa canisters, what is the critical parameter to verify before field deployment?
- Canister temperature history
- Pre-evacuated canister vacuum pressure (Correct answer)
- Color of the canister exterior coating
- Weight of the empty canister
Correct answer: Pre-evacuated canister vacuum pressure
Pre-evacuated Summa canisters must have the correct vacuum pressure verified before deployment to ensure they can draw the required air sample volume.
Question 5: Under ASTM E1527-21, which of the following is classified as a 'Recognized Environmental Condition' (REC)?
- A historical dry cleaner operation on the subject property (Correct answer)
- A tree stump from a removed mature oak
- An above-ground propane tank for residential heating
- Recently installed asphalt paving over a parking lot
Correct answer: A historical dry cleaner operation on the subject property
A historical dry cleaner operation is a classic REC because dry cleaners commonly used chlorinated solvents (PCE/TCE) that create significant contamination risk.
Question 6: What is the purpose of a 'blank' sample in groundwater sampling protocols?
- To measure the natural background concentration in the aquifer
- To identify contamination introduced during sampling and analysis (Correct answer)
- To calibrate the water level indicator before purging
- To determine the hydraulic conductivity of the formation
Correct answer: To identify contamination introduced during sampling and analysis
Blank samples (equipment, field, or trip blanks) are used to detect and quantify contamination introduced by sampling equipment, field conditions, or laboratory handling.
Question 7: Which parameter is most critical to measure immediately upon groundwater sample collection to assess sample integrity for dissolved metals analysis?
- Total dissolved solids (TDS)
- Sample turbidity using a nephelometer
- Field pH, specific conductance, and dissolved oxygen (Correct answer)
- Nitrate concentration using a colorimetric kit
Correct answer: Field pH, specific conductance, and dissolved oxygen
Field parameters including pH, specific conductance, temperature, dissolved oxygen, and ORP must be measured immediately upon collection as they change rapidly upon exposure to atmosphere.
CEA Environmental Assessment & Sampling Techniques 2
When conducting a Phase II Environmental Site Assessment, which QA/QC measure ensures laboratory results are representative of field conditions?