How to Pass the PE Environmental Exam: Complete Study Guide

Environmental engineering is about protecting public health and the environment. Whether you're designing water treatment systems, managing air emissions, or overseeing remediation projects, the PE Environmental exam tests your ability to apply environmental engineering principles across the full spectrum of environmental media: water, air, and land.

Let me help you prepare to pass this exam.

Exam Format and Structure

The PE Environmental exam is an 80-question, computer-based test (CBT) covering the breadth of environmental engineering practice. Unlike the Civil PE with its depth modules, the Environmental PE is a comprehensive exam testing all major environmental topics.

The exam consists of two 4-hour sessions (8 hours total). It's open-book, allowing printed or bound references. You'll take it at a Pearson VUE test center, available for scheduling year-round.

Pass rates for the PE Environmental typically range from 60-70%. This is a challenging exam that requires preparation across many diverse topics, but thousands of environmental engineers pass it every year.

Content Areas Breakdown

NCEES divides the PE Environmental exam into six major content areas:

1. Water Resources (15-20%)

Water quantity and conveyance:

• Hydrology (rainfall-runoff, rational method, SCS/NRCS procedures)
• Open channel flow (Manning's equation, specific energy)
• Pipe flow and pump systems (Darcy-Weisbach, Hazen-Williams)
• Stormwater management and detention basins
• Groundwater flow and well hydraulics
• Erosion control and sediment management

Even as an environmental engineer, you need hydraulics fundamentals. Know Manning's equation and the Rational Method cold.

2. Water and Wastewater (30-35%)

This is the largest content area:

Water Treatment:

• Source water quality assessment
• Coagulation and flocculation
• Sedimentation and clarification
• Filtration (rapid sand, slow sand, membrane)
• Disinfection (chlorine, chloramines, UV, ozone)
• Advanced treatment (ion exchange, activated carbon, membranes)
• Corrosion control and distribution systems

Wastewater Treatment:

• Characterization (BOD, COD, TSS, nutrients)
• Primary treatment (screening, grit removal, clarification)
• Secondary treatment (activated sludge, trickling filters, lagoons, RBC)
• Nutrient removal (nitrification, denitrification, bio-P removal)
• Advanced treatment and disinfection
• Sludge treatment and disposal (thickening, digestion, dewatering)
• Land application and biosolids management

You'll see multiple problems on activated sludge design, clarifier sizing, and disinfection. Practice these thoroughly.

3. Air Quality (15-20%)

Atmospheric pollution control:

• Air pollutants (criteria pollutants, HAPs, VOCs, greenhouse gases)
• Air dispersion modeling (Gaussian plume, stability classes)
• Combustion and emissions calculations
• Particulate control (cyclones, ESP, baghouses)
• Gas phase control (scrubbers, absorbers, adsorbers, thermal/catalytic oxidation)
• Ventilation and dilution
• Regulatory requirements (CAA, NAAQS, NSPS, PSD)

Know the criteria pollutants (PM, O3, CO, SO2, NO2, Pb) and common control technologies.

4. Solid and Hazardous Waste (15-20%)

Managing wastes safely:

• Solid waste characterization and generation rates
• Collection and transport systems
• Recycling and materials recovery
• Landfill design (liners, leachate collection, gas management, closure)
• Incineration and waste-to-energy
• Hazardous waste identification (RCRA characteristics and listings)
• Treatment and disposal of hazardous waste
• Remediation technologies (pump-and-treat, SVE, bioventing, PRBs)
• Site assessment and cleanup

RCRA regulations and landfill design are key topics. Know liner requirements and leachate management.

5. Site Assessment and Remediation (10-15%)

Cleaning up contaminated sites:

• Phase I and Phase II environmental site assessments
• Soil and groundwater sampling
• Contaminant fate and transport
• Risk assessment (exposure pathways, toxicity)
• Remediation technologies (excavation, soil vapor extraction, pump-and-treat, bioremediation, chemical oxidation)
• Monitored natural attenuation
• Vapor intrusion assessment

Understand the ESA process and common remediation approaches for different contaminant types.

6. Environmental Health and Safety (10-15%)

Protecting workers and the public:

• Industrial hygiene (exposure assessment, PPE)
• Occupational health (noise, heat stress, ergonomics)
• Toxicology basics (dose-response, LD50, carcinogens)
• Risk assessment and risk management
• Environmental regulations (CERCLA, RCRA, CAA, CWA, SDWA)
• Permitting (NPDES, air permits, solid waste permits)
• Environmental management systems

Know the major federal environmental laws and what they regulate.

Your 12-16 Week Study Plan

Here's a realistic preparation schedule:

Weeks 1-3: Water and Wastewater

Start with the largest content area:

• Week 1: Water treatment (coagulation through filtration)
• Week 2: Disinfection and wastewater primary/secondary treatment
• Week 3: Activated sludge design, nutrient removal, sludge treatment

Work practice problems for each topic. This is calculation-heavy material.

Weeks 4-5: Water Resources

Cover hydraulics and hydrology:

• Week 4: Hydraulics (Manning's, pipe flow, pumps)
• Week 5: Hydrology (runoff, detention, groundwater)

If you're weak on hydraulics, allocate extra time here.

Weeks 6-7: Air Quality

Focus on air pollution:

• Week 6: Pollutants, dispersion modeling, combustion
• Week 7: Control technologies, regulations

Practice dispersion modeling calculations and control device sizing.

Weeks 8-9: Solid and Hazardous Waste

Cover waste management:

• Week 8: Solid waste (generation, collection, landfills)
• Week 9: Hazardous waste (RCRA, treatment, disposal)

Know RCRA inside and out. It's critical.

Weeks 10-11: Site Assessment and Remediation

Study contaminated sites:

• Week 10: Site assessment, sampling, fate and transport
• Week 11: Remediation technologies, risk assessment

Week 12: Health, Safety, and Regulations

Cover remaining topics:

• Industrial hygiene and toxicology
• Environmental regulations and permitting
• Environmental management

Weeks 13-15: Practice Exams

Take full-length practice exams under timed conditions. The NCEES practice exam is mandatory. Review every problem you missed.

Week 16: Final Review

Polish weak areas, organize references, practice quick lookups, rest up.

Essential Reference Materials

Here's what to bring to the exam:

Critical:

• CERM (Civil Engineering Reference Manual) or Environmental Engineering Reference Manual
• Davis and Cornwell Environmental Engineering textbook (or similar comprehensive text)
• Metcalf & Eddy Wastewater Engineering
• AWWA Water Treatment textbook (or MWH Water Treatment)
• Air Pollution Control Engineering textbook (Noel de Nevers or similar)
• Your own formula sheets and worked problems

Highly Recommended:

• EPA design manuals (wastewater treatment, air pollution control)
• Ten States Standards (water and wastewater design)
• RCRA regulations summary
• CFR excerpts (40 CFR for environmental regs)
• Standard Methods for water/wastewater analysis

Also Useful:

• Remediation technology guides
• Risk assessment references
• Industrial hygiene references
• Breadth topic notes (if your background is narrow)

Organization:

Tab extensively by topic:

• Water treatment processes (separate tabs)
• Wastewater treatment processes
• Activated sludge equations
• Air pollution controls
• RCRA characteristics
• Remediation technologies

If you can't find information in 30 seconds, reorganize your references.

Study Strategies That Work

1. Master Activated Sludge

Activated sludge design appears on almost every PE Environmental exam. Know how to:

• Calculate SRT (solids retention time) and HRT (hydraulic retention time)
• Determine aeration basin volume
• Size secondary clarifiers
• Calculate oxygen requirements
• Estimate sludge production

Practice until you can do these calculations quickly.

2. Know Water Treatment Unit Processes

Understand how to design each unit process:

• Rapid mix and flocculation basins (detention time, G-values)
• Sedimentation (overflow rate, detention time)
• Filtration (loading rate, backwash)
• Chlorination (CT values, breakpoint chlorination)

3. Build Air Quality References

Create quick-reference sheets for:

• Gaussian dispersion equation and stability classes
• Emission factors
• Control device efficiencies
• Regulatory limits (NAAQS, etc.)

4. Understand RCRA

Know the four RCRA characteristics (ignitability, corrosivity, reactivity, toxicity). Understand listed wastes. Know treatment and disposal requirements.

5. Practice Calculations

The PE Environmental exam is computation-heavy. Practice:

• Mass balance problems
• Reactor sizing (CSTR, PFR, batch)
• Removal efficiency calculations
• Loading rate and detention time calculations
• Dilution and mixing problems

6. Create a Personal Reference Binder

Build a three-ring binder with:

• One-page summaries of each major topic
• Formula sheets
• Important tables (BOD reaction rates, air emission factors, etc.)
• Worked example problems

This becomes your first reference during the exam.

Common Mistakes to Avoid

Weak on Activated Sludge

Activated sludge shows up repeatedly. Not knowing it cold will cost you multiple questions.

Forgetting Regulations

Environmental engineering is heavily regulated. Know the major federal laws (CAA, CWA, SDWA, RCRA, CERCLA) and what they cover.

Poor Unit Tracking

Environmental engineering uses a mix of SI and US customary units. Always write down units and check dimensional consistency.

Not Practicing Enough

This exam requires calculation skills. You can't just read textbooks. You must work problems.

Bringing Unorganized References

A pile of untabbed books is useless. Organization is as important as content knowledge.

Skipping the NCEES Practice Exam

The NCEES practice exam is the best predictor of what you'll face. Not taking it is a mistake.

Problem Types You Must Master

Activated Sludge Design

Given influent characteristics and effluent requirements:

• Design aeration basin volume (SRT or F/M approach)
• Size secondary clarifier
• Calculate oxygen demand
• Estimate sludge wasting rate

Water Treatment Design

Size treatment units:

• Rapid mix and flocculation basins
• Sedimentation basins (overflow rate method)
• Filter area
• Chlorine contact time (CT calculation)

Air Dispersion Modeling

Use Gaussian plume equation to:

• Calculate downwind concentration
• Determine if emissions meet standards
• Account for stack height and stability class

Landfill Design

Design landfill components:

• Calculate liner thickness and permeability
• Size leachate collection system
• Estimate gas generation rate
• Determine landfill capacity and life

Remediation Technology Selection

Given site conditions and contaminants:

• Select appropriate remediation technology
• Size remediation system (SVE, pump-and-treat, etc.)
• Calculate cleanup time or mass removal

Reactor Design

Size reactors for treatment:

• CSTR vs. PFR for given removal efficiency
• Batch reactor time for desired conversion
• First-order decay calculations

Exam Day Strategy

Before Test Day:

• Visit test center to know location and parking
• Organize all references with extensive tabs
• Pack approved calculator, mechanical pencils, ID
• Review formula sheets
• Get 7-8 hours of sleep

During the Exam:

First Pass (60-90 min):

• Answer all questions you know immediately
• Simple lookups and straightforward calculations
• Aim for 25-35 questions

Second Pass (90-120 min):

• Work calculation-heavy problems you understand
• Treatment design, reactor sizing, etc.
• Aim for 20-30 more questions

Third Pass (remaining time):

• Tackle harder problems
• Make educated guesses on remaining questions
• Review flagged questions

Time Management:

• Average: ~6 minutes per question
• Simple problems: 2-4 minutes
• Complex calculations: 10-15 minutes
• If a problem takes >12 minutes, flag and move on

Mental Game:

The exam includes problems that will stump you. That's normal. Everyone faces this. You don't need a perfect score. Skip the impossible ones, nail the doable ones, guess intelligently on the rest.

Additional Resources

Review Courses:

• School of PE (live online)
• EET (Engineering Education & Training)
• Testmasters
• Stamp Prep (self-paced practice)

Practice Problems:

• NCEES PE Environmental Practice Exam (mandatory)
• PPI practice problems
• Textbook problems from Davis/Cornwell and Metcalf & Eddy

Online Communities:

• r/PE_exam subreddit
• Eng-Tips environmental forum
• LinkedIn PE exam study groups
• AWWA and WEF forums

Professional Organizations:

• AAEE (American Academy of Environmental Engineers)
• AWWA (American Water Works Association)
• WEF (Water Environment Federation)
• A&WMA (Air & Waste Management Association)

If You Don't Pass

If you don't pass, NCEES provides a diagnostic report showing your performance in each content area. Use this to identify weak areas for your retake.

Common failure reasons:

• Weak on activated sludge and wastewater treatment
• Insufficient practice with calculations
• Poor time management
• Gaps in air quality or solid waste knowledge
• Inadequate familiarity with regulations

You can retake after your state's waiting period (typically 60-90 days). Many successful environmental engineers didn't pass on their first attempt.

Final Thoughts

The PE Environmental exam is challenging because it covers such a broad range of topics: water, wastewater, air, solid waste, hazardous waste, and remediation. Success requires both breadth and depth of knowledge.

Start early, practice consistently, and organize your references meticulously. Master activated sludge design, understand treatment processes, know your regulations, and practice calculations relentlessly.

Most importantly, trust your preparation. You've got the education and work experience. Now you're putting in the study effort. Walk into that test center ready to demonstrate your competence as an environmental engineer.

You've got this. Now go earn your PE license.