Free FE Environmental Exam Flashcards

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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).

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.

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.

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.

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.

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.

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).

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).

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.

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.

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

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.

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.

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

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.

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

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.

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

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.

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.

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.

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

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

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.

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

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.

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.

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.

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

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

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.

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.

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.

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.

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.

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

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.

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

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.