PE Environmental flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

PM2.5 Annual NAAQS

The primary annual fine particulate standard was revised to 9.0 µg/m³ in 2024; the 24-hour PM2.5 standard remains 35 µg/m³, both averaged over three years for compliance.

Ozone NAAQS

The 2015 8-hour ozone standard is 0.070 ppm; compliance is based on the 4th-highest daily maximum 8-hour concentration averaged over three consecutive years.

Gaussian Plume Equation

Predicts downwind concentration from a continuous elevated point source: C = Q/(2πuσyσz)·exp(−y²/2σy²)·[exp(−(H−z)²/2σz²) + exp(−(H+z)²/2σz²)], where H is effective stack height.

Pasquill Stability Classes

Six turbulence categories A through F: A is most unstable (strong sun, light wind), D is neutral, and F is most stable (clear night, light wind); they select dispersion coefficients.

Deutsch Equation

Estimates electrostatic precipitator collection efficiency: η = 1 − exp(−wA/Q), where w is particle drift velocity, A is total collection plate area, and Q is gas flow rate.

ppm to mg/m³ Conversion

At 25 °C and 1 atm, mg/m³ = ppm × molecular weight / 24.45; at 0 °C use 22.414 L/mol, so mg/m³ = ppm × MW / 22.414.

Emission Factor Calculation

Mass emitted equals activity rate times emission factor times one minus fractional control efficiency: E = A × EF × (1 − ER/100), with consistent units throughout.

Ultimate BOD

L0 is the total carbonaceous oxygen demand exerted at infinite time; BOD exerted at time t equals L0(1 − e^(−k1t)), where k1 is the base-e reaction rate constant.

Streeter-Phelps Equation

Models the dissolved oxygen sag downstream of a point source: D = (k1L0/(k2−k1))(e^(−k1t) − e^(−k2t)) + D0e^(−k2t), where D is deficit below saturation and k2 is reaeration.

Secondary Treatment Limits

NPDES secondary limits are 30-day averages of 30 mg/L BOD5 and 30 mg/L total suspended solids with at least 85% removal of each, under 40 CFR 133.

TMDL Equation

Total maximum daily load equals the sum of wasteload allocations from point sources, load allocations from nonpoint sources, plus a margin of safety.

Stokes' Law Settling

For discrete particles in laminar flow, terminal velocity v = g(ρp − ρw)d²/(18μ); larger and denser particles settle faster, and higher viscosity slows settling.

CT Disinfection Concept

Disinfection credit is the product of residual disinfectant concentration in mg/L and contact time in minutes; required CT depends on target log inactivation, pH, and temperature.

Food-to-Microorganism Ratio

F/M equals BOD mass applied per day divided by microorganism mass in the aeration tank; low ratios favor nitrification and reduce sludge production.

RCRA Waste Characteristics

A solid waste is hazardous if it exhibits ignitability, corrosivity, reactivity, or toxicity; toxicity is determined by the TCLP test specified in 40 CFR 261.24.

Corrosivity Characteristic

A waste is corrosive if its aqueous portion has pH at or below 2 or at or above 12.5, or it corrodes steel faster than 6.35 mm per year.

SQG Accumulation Time

A small quantity generator may accumulate hazardous waste on site without a permit for up to 180 days and no more than 6000 kg; large generators get 90 days.

Hazardous Waste Generator Categories

Large quantity generators produce 1000 kg or more per month of hazardous waste, small quantity generators 100 to 1000 kg per month, and very small generators under 100 kg per month.

Landfill Gas Composition

Municipal landfill gas is roughly 45 to 60 percent methane and 40 to 55 percent carbon dioxide with trace VOCs; methane is explosive at 5 to 15 percent in air.

Incinerator DRE Requirement

Hazardous waste incinerators must achieve 99.99 percent destruction and removal efficiency for principal organic hazardous constituents; dioxin-listed waste requires 99.9999 percent.

Retardation Factor

R = 1 + (ρb/θ)Kd describes how much slower a contaminant moves than groundwater; Kd equals the organic carbon partition coefficient Koc times the soil organic carbon fraction.

Darcy Velocity vs Seepage Velocity

Specific discharge q = Q/A = −K(dh/dL) is Darcy velocity; seepage velocity equals q divided by effective porosity, so contaminants travel faster than Darcy velocity suggests.

Phase I ESA

A non-intrusive review of records, regulatory databases, site reconnaissance, and interviews to identify recognized environmental conditions, typically following ASTM E1527; no sampling is performed.

CERCLA Remedial Process

Site assessment leads to Hazard Ranking System scoring and possible NPL listing, then remedial investigation and feasibility study, a record of decision, and remedial design and action.

DNAPL vs LNAPL

Dense non-aqueous phase liquids such as chlorinated solvents sink below the water table, while light non-aqueous phase liquids such as gasoline float on the water table and spread laterally.

Soil Vapor Extraction

SVE removes volatile contaminants from the unsaturated zone by inducing airflow through soil; it is ineffective in saturated soils or for low-volatility compounds.

Cancer Risk Calculation

Carcinogenic risk equals chronic daily intake multiplied by the slope factor; EPA generally considers individual risks between 1×10⁻⁶ and 1×10⁻⁴ as acceptable for cleanup decisions.

Hazard Quotient

For non-carcinogens, HQ = CDI/RfD; the hazard index sums HQs across pathways and chemicals, and values above 1 indicate potential non-cancer health concern.

Chronic Daily Intake

CDI = (C × IR × EF × ED)/(BW × AT), where C is concentration, IR intake rate, EF exposure frequency, ED exposure duration, BW body weight, and AT averaging time.

HAZWOPER Training Hours

OSHA 1910.120 requires 40 hours of initial training plus 3 days of supervised field experience for general site workers, and 24 hours for limited low-risk site work.

PEL vs TLV

A PEL is the legally enforceable OSHA occupational exposure limit, while a TLV is a non-regulatory advisory value published by ACGIH; TLVs are often lower than PELs.

ALARA Principle

As low as reasonably achievable: radiation doses should be minimized below regulatory limits while weighing social and economic factors; it is a core radiation protection principle.