FE Environmental Exam Flashcards

Q: What is on the FE Environmental exam?

The FE Environmental exam covers 12 NCEES knowledge areas: mathematics/probability/statistics, ethics, engineering economics, materials science, environmental science and chemistry, risk assessment, water resources, water and wastewater engineering, air quality, solid and hazardous waste, sustainability, and environmental health and safety.

Q: How long is the FE Environmental exam and what does it cost?

FE Environmental is 110 questions in a 5-hour 20-minute Pearson VUE appointment including tutorial, scheduled break, and survey. The NCEES exam fee is $175 in 2026. An on-screen searchable FE Reference Handbook is supplied during the test.

Q: What is the FE Environmental pass rate?

NCEES first-time pass rates for FE Environmental typically run 67-74% in recent reporting windows. Plan 200-300 hours of study. Mastering the FE Reference Handbook location of formulas is the single highest-impact preparation step.

Q: Can I use a calculator on FE Environmental?

Only NCEES-approved models are permitted: HP 33s/35s, Casio FX-115 series, and TI-30X/TI-36X series. An on-screen calculator is also available. Non-approved calculators are confiscated at check-in.

Q: Is FE Environmental harder than FE Civil?

Difficulty depends on background. FE Environmental emphasizes chemistry, biology, and air/waste regulations. FE Civil is broader in structures and transportation. Pass rates are comparable. You may select any FE discipline regardless of your eventual PE specialty.

Q: What EPA rules should FE Environmental candidates know for 2026?

Know the 2024 PFAS NPDWR (4 ng/L MCL for PFOA and PFOS), 2024 Lead and Copper Rule Improvements (10 µg/L action level), 2024 PM2.5 NAAQS annual primary standard of 9 µg/m³, and updated methane reporting under NSPS Subpart W.

Question 1

BOD first-order decay

Accepted Answer

L = L₀ e^(-kt) where k is the base-10 or natural-log rate constant per handbook convention. Half-life t₁/₂ = ln(2)/k. BOD exertion models organic loading in rivers and activated sludge design.

Question 2

Streeter-Phelps DO sag curve

Accepted Answer

Models dissolved oxygen deficit downstream of a BOD discharge: deoxygenation from organic decay minus reaeration from the atmosphere. Minimum DO occurs at the sag point — critical for fishery protection and NPDES limits.

Question 3

Monod growth kinetics

Accepted Answer

μ = μ_max · S / (K_s + S). Describes microbial growth rate vs substrate concentration. Used in activated sludge and bioreactor design. K_s is the half-velocity constant.

Question 4

Henry's law (air-water partitioning)

Accepted Answer

C_a = H · C_w (or equivalent K_H forms in the handbook). Predicts volatilization of VOCs from water to air. Higher Henry's constant favors transfer to the gas phase — important for strippers and exposure assessment.

Question 5

pH and alkalinity

Accepted Answer

pH = -log[H⁺]. Alkalinity measures water's capacity to neutralize acid (primarily bicarbonate, carbonate, hydroxide). Coagulation and nitrification processes require monitoring both to prevent pH crashes.

Question 6

CT disinfection concept

Accepted Answer

Disinfection credit = C (residual mg/L) × T (contact time min). EPA Surface Water Treatment Rules set CT requirements by pathogen and disinfectant. Baffling factor reduces effective T in basins.

Question 7

Activated sludge SRT vs F:M

Accepted Answer

Solids retention time (SRT) controls biomass age and nitrification — higher SRT favors nitrifiers. Food-to-microorganism ratio (F:M) relates substrate loading to MLVSS. Both drive aeration basin sizing and wasting rate.

Question 8

Clarifier surface overflow rate (SOR)

Accepted Answer

SOR = Q / A (flow per unit area). Primary clarifiers typically target lower SOR than secondary. Excessive SOR causes solids carryover and effluent TSS violations.

Question 9

Hardness (water chemistry)

Accepted Answer

Sum of calcium and magnesium concentrations, often expressed as mg/L CaCO₃ equivalent. Causes scaling in pipes and boilers. Softening via lime-soda or ion exchange reduces hardness before industrial use.

Question 10

Nitrification stoichiometry (overview)

Accepted Answer

Ammonia oxidized to nitrite then nitrate consumes alkalinity and oxygen. Nitrifiers are slow-growing — require higher SRT than heterotrophs. Failure to nitrify causes effluent ammonia exceedances.

Question 11

MBR vs conventional activated sludge

Accepted Answer

Membrane bioreactor replaces clarifier with membrane filtration, producing higher-quality effluent in smaller footprint. Higher energy cost from pumping and scouring. Common in water reuse applications.

Question 12

GAC adsorption isotherm

Accepted Answer

Freundlich or Langmuir isotherms model contaminant uptake on granular activated carbon. Used to estimate bed life for organic micropollutant removal (e.g., taste/odor, PFAS pilot studies).

Question 13

Reverse osmosis (RO) principle

Accepted Answer

Pressure-driven membrane process rejecting dissolved ions and molecules above pore size cutoff. Produces high-purity permeate; concentrate stream requires disposal management. Energy-intensive desalination and reuse technology.

Question 14

Manning equation (open channel)

Accepted Answer

V = (1/n) R^(2/3) S^(1/2). Relates velocity to hydraulic radius, slope, and roughness n. Used for sewer capacity, culverts, and open-channel flow in water resources problems.

Question 15

Darcy's law (groundwater)

Accepted Answer

Q = -K A dh/dl. Discharge proportional to hydraulic conductivity K and hydraulic gradient. Foundation for well yield, contaminant plume migration, and pump-and-treat design.

Question 16

Theis / Cooper-Jacob (well hydraulics)

Accepted Answer

Confined aquifer drawdown vs time and distance from pumping well. Cooper-Jacob simplifies Theis for large t. Used to estimate transmissivity and storativity from pump test data.

Question 17

Rational method (peak runoff)

Accepted Answer

Q = C i A. Estimates peak discharge from impervious watersheds. C = runoff coefficient, i = rainfall intensity for design storm duration, A = drainage area. Limited to small urban catchments.

Question 18

NAAQS (criteria pollutants)

Accepted Answer

EPA National Ambient Air Quality Standards for six criteria pollutants: CO, Pb, NO₂, O₃, PM, SO₂. Primary standards protect health; secondary protect welfare. PM2.5 annual primary revised to 9 µg/m³ (2024).

Question 19

Gaussian plume dispersion model

Accepted Answer

Estimates ground-level pollutant concentration from a continuous point source using wind speed, stack height, emission rate, and atmospheric stability class (Pasquill-Gifford σ values).

Question 20

AP-42 emission factors

Accepted Answer

EPA compilation of default emission rates by source type and process (lb/ton, lb/MMBtu). Used when site-specific stack test data are unavailable for inventory and permit applications.

Question 21

ESP vs baghouse

Accepted Answer

Electrostatic precipitator charges particles for collection on plates — effective on fly ash but sensitive to resistivity. Fabric filter (baghouse) captures dust on bags — very high efficiency on PM2.5 with proper fabric.

Question 22

SCR and FGD (air pollution control)

Accepted Answer

Selective catalytic reduction removes NOx using NH₃ and catalyst. Flue gas desulfurization (scrubber) removes SO₂ — wet limestone FGD is common on coal-fired units.

Question 23

NSR / PSD (major sources)

Accepted Answer

New Source Review requires permits and BACT/LAER for new or modified major sources in attainment/nonattainment areas. Prevention of Significant Deterioration adds increment analysis in attainment regions.

Question 24

RCRA Subtitle C vs D

Accepted Answer

Subtitle C: hazardous waste from cradle to grave (manifests, TSDF permits, LDR). Subtitle D: non-hazardous municipal and industrial solid waste landfills with liner and leachate requirements.

Question 25

RCRA characteristic waste (D-codes)

Accepted Answer

Hazardous without listing if ignitable (D001), corrosive (D002), reactive (D003), or toxic via TCLP (D004-D043). TCLP simulates landfill leaching to classify toxicity.

Question 26

RCRA listed hazardous waste (F, K, P, U)

Accepted Answer

F-list: non-specific source (solvents). K-list: specific industries. P/U-list: discarded commercial chemical products. Listed wastes are hazardous regardless of TCLP result unless delisted.

Question 27

Uniform Hazardous Waste Manifest

Accepted Answer

Multi-copy shipping document tracking hazardous waste from generator to transporter to TSDF. Generator initiates; designated facility signs receipt. Required for Subtitle C shipments.

Question 28

Landfill composite liner (Subtitle D/C)

Accepted Answer

Subtitle C hazardous waste landfills require double liner and leachate collection. Subtitle D MSW landfills require composite liner (geomembrane + compacted clay) and leachate monitoring per EPA Part 258.

Question 29

EPA risk assessment paradigm (4 steps)

Accepted Answer

(1) Hazard identification, (2) dose-response assessment, (3) exposure assessment, (4) risk characterization. Produces non-cancer HQ and cancer risk estimates for regulatory decisions.

Question 30

Hazard quotient (HQ)

Accepted Answer

HQ = CDI / RfD (chronic daily intake ÷ reference dose). HQ > 1 suggests potential non-cancer risk for a single pathway. Sum HQs across chemicals with similar endpoints for screening.

Question 31

Cancer slope factor risk

Accepted Answer

Risk = CDI × SF (slope factor). EPA often uses target risk range 10⁻⁶ to 10⁻⁴ for cleanup decisions. SF converts estimated intake to excess lifetime cancer probability.

Question 32

Chronic daily intake (CDI)

Accepted Answer

CDI = (C × IR × EF × ED) / (BW × AT). Combines concentration, intake rate, exposure frequency/duration, body weight, and averaging time. Core exposure equation in risk assessment problems.

Question 33

Triple Bottom Line (sustainability)

Accepted Answer

People, planet, profit — framework balancing social, environmental, and economic performance. Used in corporate sustainability reporting and green infrastructure justification.

Question 34

ISO 14040/14044 LCA framework

Accepted Answer

Life cycle assessment: goal/scope definition, inventory analysis (LCI), impact assessment (LCIA), interpretation. Evaluates environmental burdens from raw material extraction through disposal.

Question 35

Global warming potential (GWP)

Accepted Answer

Compares greenhouse gas radiative forcing to CO₂ over a time horizon (typically 100 years). CH₄ and N₂O have higher GWP values — used in GHG inventories and carbon footprint calculations.

Question 36

Hierarchy of controls (OSHA)

Accepted Answer

Elimination → substitution → engineering controls → administrative controls → PPE. Preferred order for reducing worker exposure. PPE is the least preferred reliance for chronic hazards.

Question 37

OSHA noise dose and PEL

Accepted Answer

8-hour TWA PEL = 90 dBA; exchange rate 5 dB for dose calculation in many formulas. Action level 85 dBA triggers hearing conservation program. Dose integrates time at varying levels.

Question 38

EPCRA Section 313 (TRI)

Accepted Answer

Toxic Release Inventory requires facilities meeting thresholds to report annual releases of listed chemicals to air, water, land, and off-site transfer. Public right-to-know statute.

Question 39

PVC vs HDPE pipe (materials)

Accepted Answer

PVC: rigid, chemical-resistant, common in water distribution and conduit. HDPE: flexible, fused joints, trenchless and landfill liner applications. Both appear in FE materials and waste design questions.

Question 40

Galvanic corrosion series

Accepted Answer

When dissimilar metals contact in electrolyte, the more anodic metal corrodes preferentially. Cathodic protection (sacrificial anode or impressed current) mitigates pipeline and tank corrosion.

Question 41

Sulfate-resistant cement (ASTM C150 Type V)

Accepted Answer

Low C₃A content resists sulfate attack in soils and wastewater environments. Specified for concrete exposed to high-sulfate groundwater or aggressive industrial effluent.

Question 42

NCEES Model Rules: paramount canon

Accepted Answer

Engineers shall hold paramount the safety, health, and welfare of the public. Overrides client interest when conflicts arise. Basis for disciplinary action by state licensing boards.

Question 43

Conflict of interest (engineering ethics)

Accepted Answer

Engineers must disclose known or potential conflicts to employers and clients. Cannot accept compensation from more than one party on a project unless disclosed and agreed by all.

Question 44

Sealing of engineering documents

Accepted Answer

Only licensed PEs (or EIT/EI where permitted) may seal plans and specifications when required by jurisdiction. FE holders cannot seal — FE is the first step toward licensure.

Question 45

Benefit-cost ratio (B/C)

Accepted Answer

B/C = PW(benefits) / PW(costs). B/C > 1 indicates economic justification for a single alternative. Mutually exclusive projects require incremental B/C or NPW comparison.

Question 46

Present worth (P/F factor)

Accepted Answer

P = F(P/F, i, n) = F / (1+i)^n. Converts future single sum to present value at discount rate i over n periods. Core time-value-of-money calculation on FE economics items.

Question 47

Annual worth vs present worth

Accepted Answer

AW spreads costs/benefits into equivalent uniform annual series. Preferred when comparing alternatives with different lives without repeating entire analysis in common-period PW.

Question 48

First-order decay half-life

Accepted Answer

t₁/₂ = ln(2)/k = 0.693/k. Applies to radioactive decay, BOD, and reactor concentration when dC/dt = -kC. FE Environmental uses this across chemistry and kinetics problems.

Question 49

Log-normal environmental data

Accepted Answer

Concentrations are often log-normally distributed. Take natural log before computing percentiles or confidence limits assuming normality, then exponentiate results back to original units.

Question 50

2024 PFAS NPDWR (exam-relevant MCLs)

Accepted Answer

EPA finalized enforceable MCLs of 4 ng/L each for PFOA and PFOS in drinking water (2024). Hazard Index approach for PFNA, PFHxS, PFBS, and GenX. Know MCL values for regulatory comparison questions.

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