Water
24-36%of exam
Solid and Hazardous Waste
14-21%of exam
Sustainability
9-14%of exam
Air Quality
16-25%of exam
Site Assessment and Remediation
16-25%of exam
Environmental and Occupational Health
9-14%of exam
Quick Facts
- Exam
- PE Environmental
- Body
- NCEES
- Format
- CBT, year-round
- Questions
- 80 questions
- Appointment
- 9 hours total
- Exam Time
- 8 hours
- Fee
- $400 to NCEES
- First-Time Pass
- 73% (Jan-Jun 2026)
- Repeat Pass
- 54% (Jan-Jun 2026)
- Passing Score
- Scaled, not published
- Reference
- Electronic handbook only
Baffling Factor Scale
Unbaffled .1, poor .3, average .5, superior .7, plug 1.0
0.1: no baffles at all0.5: average baffling design0.7: superior baffling design1.0: true plug flow
MCL vs MCLG
MCL
- Enforceable legal limit
- Feasible given treatment and cost
MCLG
- Non-enforceable health goal
- Zero for known carcinogens
Enforceable vs aspirational
Water & Wastewater Treatment
- Coagulation
- Destabilizes colloidal particles
- Flocculation
- Aggregates into settleable floc
- Sedimentation
- Gravity settling in basin
- Filtration
- Typical rate 2-4 gpm/ft2
- Disinfection
- Inactivates pathogens via CT
- Jar Test
- Bench test picks coagulant dose
- DAF
- Air bubbles float out solids
Alkalinity vs Hardness
Alkalinity
- Acid-neutralizing capacity
- Driven by bicarbonate and carbonate
Hardness
- Dissolved calcium and magnesium
- Not the same as alkalinity
Buffering vs mineral content
Disinfection CT & Baffling
- CT
- Concentration times contact time
- T10
- Actual CT contact time
- Baffling Factor
- T10 over theoretical V/Q
- Unbaffled BF
- 0.1
- Poor BF
- 0.3
- Average BF
- 0.5
- Superior BF
- 0.7
- Plug Flow BF
- 1.0, ideal contact
Drinking Water MCLs
- Nitrate MCL
- 10 mg/L as N
- Arsenic MCL
- 0.010 mg/L
- TTHM MCL
- 0.080 mg/L
- Lead Action Level
- 0.015 mg/L, current rule
- LCRI Lead AL
- 0.010 mg/L, Nov 2027
- Copper Action Level
- 1.3 mg/L
- PFOA/PFOS MCL
- 4.0 ppt, due 2029
- LRAA
- Per-site running annual average
Biological Treatment & SRT
- BOD5
- 5-day oxygen demand test
- SRT
- Solids age in aeration basin
- HRT
- Tank volume over flow rate
- MLSS
- Mixed liquor suspended solids
- F/M Ratio
- Food to microorganism loading
- Yobs
- Observed yield, falls with SRT
- Nitrification
- Ammonia oxidized to nitrate
- Chlorine Feed
- MGD x dose x 8.34
Waste Hierarchy Order
Reduce, then recycle, then recover energy, then dispose
Reduce/reuse: most preferredRecycle/compost: second choiceEnergy recovery: combustion plus captureLandfill: least preferred
SQG vs LQG
SQG
- 100 to 1,000 kg/mo
- Fewer accumulation requirements
LQG
- 1,000+ kg/mo
- 90-day accumulation limit
Monthly volume sets category
Waste Management Hierarchy
- Can eliminate the waste→Source reduction, reuse(Most preferred option)
- Can't reduce, can divert→Recycling, composting(Second choice)
- Can't divert the material→Energy recovery(Combustion with recovery)
- No other option remains→Landfill disposal(Least preferred option)
RCRA Waste Characteristics
- Ignitability D001
- Flash point below 60°C
- Corrosivity D002
- pH ≤2 or ≥12.5
- Reactivity D003
- 8 criteria, e.g. toxic gas
- Toxicity TCLP
- 40 CFR 261.24, D004-D043
- TCLP Benzene
- 0.5 mg/L (D018)
- TCLP Lead
- 5.0 mg/L (D008)
- TCLP DAF
- ~100x health-based drinking level
Generator Size Order
VSQG under SQG under LQG, ranked by kg per month
VSQG: 100 kg/mo or lessSQG: 100 to 1,000 kg/moLQG: 1,000+ kg/mo
DAF: Two Different Meanings
Dissolved Air Flotation
- Water and wastewater unit process
- Air bubbles float out solids
Dilution Attenuation Factor
- TCLP threshold derivation
- About 100x the health level
Same acronym, different exam topics
RCRA Generator Categories
- VSQG
- 100 kg/mo hazardous waste max
- VSQG Acute
- 1 kg/mo acute waste max
- SQG
- 100 to 1,000 kg/mo
- LQG
- 1,000+ kg/mo hazardous waste
- LQG Acute
- Over 1 kg/mo acute waste
- Satellite Accumulation
- 55-gallon limit at generation point
- LQG Storage Time
- 90 days max on-site
Landfill Design (Subtitle D)
- Daily Cover
- 6 inches soil, each day
- Final Cover Infiltration
- 18 inches, tight as liner
- Final Cover Cap
- 1e-5 cm/s permeability, or less
- Erosion Layer
- 6 inches, supports vegetation
- Bathtub Effect
- Tight cover traps infiltrating water
- Composite Liner
- Beneath the waste cell
Sustainability & LCA
- LCA
- ISO 14040, four phases
- Goal & Scope
- LCA phase one
- LCI
- Inventory of inputs and outputs
- LCIA
- Translates flows into impacts
- Embodied Carbon
- Materials, transport, end-of-life emissions
- Operational Carbon
- Ongoing energy-use emissions
- Circular Economy
- Reuse and repair loops
- Reliability, Series
- Multiply each component's reliability
- Reliability, Parallel
- Fails only if all fail
SCR vs SNCR
SCR
- Catalyst present
- Lower flue-gas temperature
- Higher NOx removal
SNCR
- No catalyst used
- Hotter injection zone
- Lower removal, lower cost
Catalyst raises removal and cost
Air Pollution Control Picker
- Fine particulate, high efficiency→Electrostatic Precipitator(Charged collection plates)
- Dry dust, moderate gas temperature→Fabric Filter Baghouse(Very high PM efficiency)
- Particulate plus gas removal→Venturi Scrubber(Wet droplet capture)
- High NOx removal needed→SCR(Catalyst, lower temperature)
- Lower cost, less removal→SNCR(No catalyst, hotter zone)
- Elevated stack, need concentration→Gaussian Plume Model(C falls as wind rises)
Air Quality & NAAQS
- NAAQS
- 6 criteria pollutants under CAA
- PM2.5 Annual
- 9.0 µg/m3 primary standard
- PM2.5 24-Hour
- 35 µg/m3 primary standard
- Attainment Area
- Meets the NAAQS
- Nonattainment Area
- Exceeds a NAAQS, needs SIP
- Title V Threshold
- 100 tpy; HAPs 10/25 tpy
- SIP
- State plan to reach attainment
- Gaussian Plume
- Peak drops as wind rises
ESA Sequence
Phase I screens the site, Phase II confirms and samples
Phase I: no sampling donePhase II: borings plus wellsA REC triggers Phase II
Phase I vs Phase II ESA
Phase I
- Non-intrusive records review
- Finds RECs, no sampling
Phase II
- Intrusive borings and wells
- Confirms and characterizes contamination
Screen first, then confirm
Remediation Technology Picker
- VOCs in vadose zone→Soil Vapor Extraction(Vacuum volatilizes VOCs)
- VOCs below water table→Air Sparging(Often paired with SVE)
- Dissolved plume containment→Pump-and-Treat(Extract, treat, discharge)
- Need fast in-situ destruction→ISCO(Permanganate, persulfate, or Fenton's)
- Slow-desorbing sorbed mass→Bioremediation(Long operating timeline)
- Need REC screening only→Phase I ESA(No sampling required)
- REC confirmed, need data→Phase II ESA(Borings plus monitoring wells)
- Checking non-cancer risk→Hazard Quotient(HQ at or below 1)
Site Assessment & Remediation
- Phase I ESA
- Records review, finds RECs
- REC
- Recognized environmental condition
- Phase II ESA
- Borings, wells, lab analysis
- Hazard Quotient
- Intake over reference dose
- Cancer Risk
- Intake times slope factor
- Acceptable Risk Range
- 1e-6 to 1e-4 risk
- SVE
- Vacuum pulls VOCs from soil
- Air Sparging
- Injects air below water table
- Pump-and-Treat
- Extract, treat, then discharge
- ISCO
- Oxidants destroy contaminants in place
- CERCLA
- Superfund cleanup and liability law
- PRP
- Potentially responsible, strict liability
Hazard Quotient vs Cancer Risk
Hazard Quotient
- Intake over reference dose
- For non-carcinogens
- At or below 1 is fine
Cancer Risk
- Intake times slope factor
- For carcinogens
- 1e-6 to 1e-4 acceptable
Ratio vs probability
SVE vs Air Sparging
SVE
- Vacuum, vadose zone
- Extracts vapor above water table
Air Sparging
- Injects air below water table
- Volatilizes dissolved-phase VOCs
Above vs below the water table
PPE Levels A-D
A = SCBA suit, B = air, C = APR, D = uniform
Level A: max protectionLevel B: less skin, same airLevel C: known contaminant, APRLevel D: no hazard present
PEL vs TLV
OSHA PEL
- Legally enforceable limit
- Many date to the 1970s
ACGIH TLV
- Voluntary guideline only
- Updated more often, often lower
Enforceable vs advisory
Confined Space Entry Test Order
- Entering a confined space→Test oxygen first(19.5% to 23.5%)
- Oxygen reading in range→Test flammability next(Below 10% LFL)
- Flammability reading in range→Test toxics last(Below the PEL)
- Noise TWA hits 85 dBA→Start hearing conservation(Action level, not PEL)
- Noise TWA above 90 dBA→Exceeds the noise PEL(Feasible controls required)
- Contaminant identity unknown→Wear Level B PPE(Until air is characterized)
OSHA & HAZWOPER Limits
- OSHA PEL
- Legally enforceable exposure limit
- ACGIH TLV
- Voluntary, often stricter guideline
- Noise PEL
- 90 dBA, 8-hour TWA
- Noise Action Level
- 85 dBA triggers hearing program
- Exchange Rate
- 5 dB halves allowed time
- Benzene PEL
- 1 ppm, 8-hour TWA
- Benzene STEL
- 5 ppm over 15 minutes
- Benzene Action Level
- 0.5 ppm triggers monitoring
- Confined Space O2
- 19.5% to 23.5% acceptable
- Confined Space LFL
- Below 10% lower flammable limit
- HAZWOPER Level A
- Full encapsulating suit plus SCBA
- HAZWOPER Level D
- Uniform only, no hazard
Common Traps
TCLP vs Drinking Water MCL
TCLP sets waste thresholds ≠ MCL sets drinking water limits
Stage 1 vs Stage 2 TTHM
Stage 1 used one system RAA ≠ Stage 2 uses per-site LRAA
Action Level vs PEL
Action level triggers monitoring ≠ PEL is the enforceable ceiling
NSPS vs NESHAP
NSPS covers new-source criteria pollutants ≠ NESHAP under CAA 112 covers HAPs
Attainment vs Nonattainment
Attainment area meets the NAAQS ≠ Nonattainment area exceeds a NAAQS
Sustainability vs Resilience
Sustainability is long-term stewardship ≠ Resilience is disruption recovery
Series vs Parallel Reliability
Series: each component lowers reliability ≠ Parallel: redundancy raises reliability
Last Minute
- 1.80 questions in an 8-hour exam
- 2.$400 exam fee, paid to NCEES
- 3.Closed book: only NCEES's e-handbook allowed
- 4.No published passing score; it's scaled
- 5.Pass rate: 73% first-time, 54% repeat
- 6.Retake limit: 3 attempts per year
- 7.Water is biggest domain, 19-29 Qs
- 8.Sustainability domain is brand-new in 2026
- 9.T10 is real CT contact time
- 10.Test O2, then flammables, then toxics
- 11.Noise action level: 85 dBA TWA
- 12.TCLP limits run about 100x MCLs
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