NCEES Environmental Engineering PE Exam 2 — Questions and Answers
Question 1: On the NCEES PE Environmental exam, which air pollutant is the primary precursor to ground-level ozone formation?
- Sulfur dioxide (SO2)
- Carbon monoxide (CO)
- Volatile organic compounds (VOCs) and NOx reacting in sunlight (Correct answer)
- Particulate matter (PM2.5)
Correct answer: Volatile organic compounds (VOCs) and NOx reacting in sunlight
Ground-level ozone forms through photochemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight — the basis of urban smog.
Question 2: In the NCEES PE Environmental exam, what does the 'NPDES permit' system regulate under the Clean Water Act?
- National Primary Drinking water standards for public supplies
- Point source discharges of pollutants into waters of the United States (Correct answer)
- Non-point source agricultural runoff practices
- Underground injection of hazardous waste
Correct answer: Point source discharges of pollutants into waters of the United States
The National Pollutant Discharge Elimination System (NPDES) requires permits for all point source discharges to surface waters, setting effluent limits based on technology and water quality standards.
Question 3: For the NCEES PE Environmental exam, what is 'nitrification' in biological wastewater treatment?
- The biological conversion of nitrate to nitrogen gas (denitrification)
- The aerobic microbial oxidation of ammonia to nitrite and then to nitrate (Correct answer)
- The chemical precipitation of nitrogen as struvite
- The removal of nitrogen via ion exchange resins
Correct answer: The aerobic microbial oxidation of ammonia to nitrite and then to nitrate
Nitrification is a two-step aerobic process: Nitrosomonas converts ammonia to nitrite, then Nitrobacter converts nitrite to nitrate, requiring substantial oxygen and alkalinity.
Question 4: On the NCEES PE Environmental exam, what does 'fate and transport' modeling of contaminants in groundwater evaluate?
- The cost of groundwater extraction for remediation
- How contaminants move, dilute, and degrade in the subsurface over time (Correct answer)
- The pumping test for aquifer characterization
- The well screen design for monitoring wells
Correct answer: How contaminants move, dilute, and degrade in the subsurface over time
Fate and transport modeling predicts contaminant plume migration, dilution, adsorption, and biodegradation in groundwater to assess risk and design remediation strategies.
Question 5: In the NCEES PE Environmental exam, which metric is used to design disinfection systems using the CT concept?
- Chlorine dose in mg/L
- The product of disinfectant concentration (C) and contact time (T) required for a specified log inactivation of pathogens (Correct answer)
- The pH and temperature correction factor
- The ratio of chlorine demand to dose
Correct answer: The product of disinfectant concentration (C) and contact time (T) required for a specified log inactivation of pathogens
CT (concentration × time) is the fundamental design metric for chemical disinfection; regulators specify CT values (in mg/L·min) required to achieve target log-inactivation of Giardia, Cryptosporidium, and viruses.
Question 6: For the NCEES PE Environmental exam, what is the function of a 'landfill liner system' under RCRA Subtitle D regulations?
- To accelerate decomposition of organic waste
- To prevent leachate migration from the landfill into groundwater through low-permeability barriers (Correct answer)
- To collect and combust landfill gas for energy
- To stabilize the landfill slope against failure
Correct answer: To prevent leachate migration from the landfill into groundwater through low-permeability barriers
RCRA Subtitle D requires composite liner systems (geomembrane + compacted clay) and leachate collection systems to prevent contaminated leachate from reaching groundwater.
NCEES Environmental Engineering PE Exam 2
On the NCEES PE Environmental exam, which air pollutant is the primary precursor to ground-level ozone formation?