CES Environmental Sampling & Data Analysis 3 — Questions and Answers
Question 1: Which data quality indicator (DQI) specifically addresses whether the sampling locations and design are sufficient to represent the study area?
- Precision
- Accuracy
- Completeness
- Representativeness (Correct answer)
Correct answer: Representativeness
Representativeness reflects how well sample results characterize the true conditions of the population or area being studied.
Question 2: When using a GPS unit to document sampling locations in a wetland delineation, which coordinate system is most commonly specified in USACE jurisdictional determinations?
- State Plane Coordinate System (SPCS)
- Universal Transverse Mercator (UTM)
- WGS84 decimal degrees latitude/longitude (Correct answer)
- NAD27 geographic coordinates
Correct answer: WGS84 decimal degrees latitude/longitude
The USACE and most federal environmental agencies record sample locations as WGS84 decimal degrees latitude/longitude for compatibility with standard GIS and GPS systems.
Question 3: A soil sample collected for PAH analysis must be stored at 4°C and analyzed within 14 days. What holding time violation occurs if the sample is analyzed on day 15?
- Method detection limit exceedance
- Chain of custody break
- Holding time exceedance (Correct answer)
- Sample preservation failure
Correct answer: Holding time exceedance
Analyzing a sample after its specified holding time is a holding time exceedance, which may render the data unusable or require qualification.
Question 4: In a systematic grid sampling design, what is the primary advantage over simple random sampling for soil contamination assessment?
- It requires fewer samples to achieve the same statistical power
- It ensures spatial coverage and reduces the risk of missing contaminated areas (Correct answer)
- It eliminates the need for field duplicates
- It produces normally distributed datasets automatically
Correct answer: It ensures spatial coverage and reduces the risk of missing contaminated areas
Systematic grid sampling provides uniform spatial coverage across the study area, reducing the chance of missing isolated contamination hotspots.
Question 5: What is the function of an internal standard in GC/MS analysis of environmental samples?
- To verify the purity of the mobile phase
- To calibrate detector response and correct for instrument variability between injections (Correct answer)
- To identify unknown compounds in the sample matrix
- To ensure the column temperature program is accurate
Correct answer: To calibrate detector response and correct for instrument variability between injections
Internal standards are compounds added at a known concentration before injection to correct for instrument response variability and injection volume differences.
Question 6: Which EPA document provides the primary guidance for the development of a Sampling and Analysis Plan (SAP) at Superfund sites?
- EPA SW-846 Test Methods for Evaluating Solid Waste
- EPA Guidance for Quality Assurance Project Plans (QA/G-5) (Correct answer)
- EPA Risk Assessment Guidance for Superfund (RAGS)
- EPA National Contingency Plan (NCP) 40 CFR Part 300
Correct answer: EPA Guidance for Quality Assurance Project Plans (QA/G-5)
EPA QA/G-5 provides the framework for developing Quality Assurance Project Plans, which are required components of Sampling and Analysis Plans at Superfund sites.
Question 7: When performing a low-flow groundwater sampling event, which field parameter stabilization criterion signals that the well is ready for sample collection?
- pH ±0.1, specific conductance ±3%, dissolved oxygen ±0.3 mg/L, ORP ±10 mV, turbidity <10 NTU (Correct answer)
- pH ±0.5, temperature ±1°C, dissolved oxygen ±1 mg/L, turbidity <100 NTU
- pH ±0.2, specific conductance ±5%, dissolved oxygen ±0.5 mg/L, turbidity <50 NTU
- pH ±1.0, specific conductance ±10%, dissolved oxygen ±2 mg/L, turbidity <200 NTU
Correct answer: pH ±0.1, specific conductance ±3%, dissolved oxygen ±0.3 mg/L, ORP ±10 mV, turbidity <10 NTU
EPA low-flow sampling guidance specifies tight stabilization criteria (pH ±0.1, SC ±3%, DO ±0.3 mg/L, ORP ±10 mV, turbidity <10 NTU) to confirm formation water is being sampled.
CES Environmental Sampling & Data Analysis 3
Which data quality indicator (DQI) specifically addresses whether the sampling locations and design are sufficient to represent the study area?