Data Collection & Analysis Flashcards
7 cards from real CSM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Data Collection & Analysis flashcards as text
Which holding time and preservation method is correct for a stormwater sample collected for total phosphorus analysis?
Answer: 28 days, preserved with sulfuric acid to pH <2 at 4°C
Total phosphorus samples must be preserved with H₂SO₄ to pH <2 and held at 4°C with a 28-day holding time per EPA Method 365 requirements.
A control chart used in stormwater laboratory QA/QC plots measured values of check standards over time. Points consistently falling above the upper control limit indicate:
Answer: A systematic positive bias in the analytical method or instrument
Persistent exceedances of the upper control limit indicate a systematic positive bias — likely instrument drift, reagent contamination, or calibration error — requiring corrective action before data are accepted.
A stormwater program wants to detect a 20% reduction in annual total nitrogen load after installing stream buffers. Which data collection design best supports this objective?
Answer: Before-after control-impact (BACI) design with continuous flow and water quality monitoring
A BACI design monitors paired treatment and control watersheds before and after BMP installation, isolating BMP effects from background variability and providing statistically defensible load comparisons.
In a hydrograph separation technique, 'baseflow' represents:
Answer: The sustained groundwater contribution to streamflow between storm events
Baseflow is the groundwater-fed component of streamflow that sustains flows during dry periods; separating it from quick-response runoff is essential for accurate pollutant load calculations.
When reporting stormwater monitoring results to a regulatory agency, data flagged with a 'J' qualifier means:
Answer: The result is estimated because it falls below the reporting limit but above the detection limit
A 'J' qualifier (estimated value) indicates a concentration was detected but falls in the range between the method detection limit and the practical quantitation limit, making it a semi-quantitative estimate.
The Rational Method (Q = CiA) is most appropriately applied to:
Answer: Small urban drainage areas to estimate peak runoff rates for inlet or pipe design
The Rational Method is designed for small, highly impervious urban catchments (typically <200 acres) where its assumptions of uniform rainfall and constant runoff coefficient are most defensible.
What is the primary limitation of using only event mean concentrations (EMCs) from a literature database rather than site-specific monitoring data for stormwater load estimates?
Answer: Literature EMCs may not reflect local land use characteristics, climate, or pollutant sources at the project site
Published EMC values are derived from diverse locations and conditions; applying them without site-specific data introduces uncertainty because local land use intensity, rainfall patterns, and pollutant sources significantly affect actual concentrations.