Cheat sheet
PE Water Resources Cheat Sheet
Planning + Sitework
- 16-25% of exam
- Project Planning Project Sitework Takeoffs Schedules Erosion Control Safety
Soils + Materials
- 9-14% of exam
- Soil Mechanics Materials USCS Compaction Pipe Materials
Hydraulics
- 25-39% of exam
- Analysis Design Closed Conduit Open Channel Pump Checks HGL vs EGL
Hydrology + Groundwater
- 15-23% of exam
- Hydrology Groundwater Wells Runoff Methods IDF Drawdown
Water + Wastewater
- 23-35% of exam
- Water Quality Drinking Water Wastewater Nutrients Disinfection
Quick Facts
- Exam PE Civil WRE
- Owner NCEES
- Format CBT closed book
- Questions 80
- Time 9-hour appointment
- References Electronic only
- Spec April 2024
- Fee $400
- Pass rate 68% first-time
Project Planning PL
- Takeoff Measured quantities
- Unit price Quantity times rate
- Lump sum Single allowance
- Critical path Zero-float sequence
- Present worth Today's equivalent cost
- Lifecycle cost Total ownership cost
Project Sitework PL
- Cut/fill Earthwork balance
- Grading Shape drainage
- Benchmarks Elevation control
- ESC Erosion sediment control
- Silt fence Perimeter control
- Outlet protection Prevent scour
- Work zone Safety control
- Retaining wall Lateral support
- Adjacent facilities Protect neighbors
Soil Mechanics SO
- Active pressure Wall yielding
- At-rest pressure No wall movement
- Surcharge Extra surface load
- Compaction Dry density target
- Bearing capacity Shear support
- Settlement Service deformation
Materials SO
- USCS Grain size + plasticity
- No. 200 Fines divider
- Slump Fresh workability
- Cylinders Strength acceptance
- PVC Corrosion resistance
- Ductile iron Pressure strength
Continuity HY
- Q stays; V changes with A
- Q=VA Smaller A Higher V Same flow
HGL vs EGL HY
HGL
- Pressure head
- Elevation head
- Grade line
EGL
- Adds velocity
- Total energy
- Above HGL
- Pressure vs energy
Hydraulics Picker HY
- Pipe continuity → Q=VA ( Flow balance )
- Pressure energy → Bernoulli ( Grade lines )
- Pipe friction → Darcy-Weisbach ( Headloss )
- Water mains → Hazen-Williams ( Empirical )
- Uniform channel → Manning ( Free surface )
- Flow regime → Froude ( Critical check )
- Pump selection → System curve ( Operating point )
- Cavitation risk → NPSH ( Suction check )
Analysis Design HY
- Mass balance In minus out
- Steady state No accumulation
- HLR Flow per area
- SLR Solids per area
- Detention time Volume over flow
- Weir Level to flow
- Flume Channel flow
Grade Lines HY
- EGL rides one velocity head higher
- HGL: pressure+z EGL: +V2/2g Losses drop Pumps lift
Darcy vs Hazen HY
Darcy-Weisbach
- Broad equation
- Friction factor
- Any fluid
Hazen-Williams
- Water pipes
- C factor
- Empirical
- General vs water-only
Closed Conduit HY
- Continuity Q=VA
- Bernoulli Energy accounting
- HGL Pressure + elevation
- EGL HGL + velocity head
- Major loss Pipe friction
- Minor loss Fittings/entrances/exits
- Pump curve Added head
- NPSH Cavitation check
Manning vs Bernoulli HY
Manning
- Open channel
- Roughness slope
- Uniform flow
Bernoulli
- Energy balance
- Pressure conduits
- Grade lines
- Uniform flow vs energy
Open Channel HY
- Manning Uniform open flow
- Hydraulic radius Area over wetted perimeter
- Froude Regime indicator
- Subcritical Deep slow flow
- Supercritical Shallow fast flow
- Critical depth Minimum specific energy
- Hydraulic jump Energy dissipation
- Culvert control Governing headwater
Subcritical vs Supercritical HY
Subcritical
- Deep slow
- Downstream control
- Fr below 1
Supercritical
- Shallow fast
- Upstream control
- Fr above 1
- Slow vs fast
Runoff HY
- Shorter Tc means higher i
- Tc IDF Q=CIA Peak flow
Detention vs Retention HY
Detention
- Temporary storage
- Releases flow
- Lowers peak
Retention
- Permanent pool
- Keeps volume
- Promotes treatment
- Delay vs store
Hydrology Picker HY
- Small peak → Rational ( Q=CIA )
- Runoff depth → NRCS CN ( Losses )
- Rain intensity → IDF ( Duration match )
- Travel time → Tc ( Distant point )
- Route peak → Detention ( Delay release )
- Stream stage → Rating curve ( Stage-flow )
Hydrology HY
- Rational Peak small-area flow
- IDF Intensity duration frequency
- Tc Longest travel time
- CN Runoff potential
- Hydrograph Flow over time
- Peak flow Max ordinate
- Runoff volume Hydrograph area
- Detention Delayed release
- Retention Permanent storage
Groundwater Wells HY
- Aquifer Water-bearing formation
- Confined Pressurized aquifer
- Unconfined Water-table aquifer
- Darcy law Groundwater flow
- Gradient Head loss slope
- Drawdown Pumping head loss
- Interference Overlapping cones
Treatment Train WA
- Coag, floc, settle, filter, disinfect
- Coagulation Flocculation Sedimentation Filtration
BOD vs DO WA
BOD
- Oxygen demand
- Organic load
- Consumes oxygen
DO
- Available oxygen
- Stream health
- Sag curve
- Demand vs supply
Treatment Picker WA
- Turbidity removal → Conventional train ( Coag to filter )
- Pathogen control → Disinfection ( CT/residual )
- Hardness removal → Softening ( Calcium/magnesium )
- Ammonia removal → Nitrification ( Aerobic )
- Nitrogen removal → Denitrification ( Anoxic )
- Collection spikes → I/I review ( Wet weather )
- Sludge volume → Dewatering ( Water removal )
Water Quality WA
- BOD Oxygen demand
- DO Dissolved oxygen
- TMDL Allowable pollutant load
- Eutrophication Nutrient-driven growth
- Nitrate Nutrient contaminant
- Sorption Slower transport
- Decay Concentration reduction
Nitrogen WA
- Nitrify with oxygen; denitrify without
- Aerobic Anoxic Ammonia Nitrate
Nitrification vs Denitrification WA
Nitrification
- Aerobic
- Ammonia to nitrate
- Needs oxygen
Denitrification
- Anoxic
- Nitrate to nitrogen
- Removes nitrogen
- Oxygen vs no oxygen
Drinking Water WA
- ADD Average day demand
- MDD Maximum day demand
- Peak hour Instant high demand
- Coagulation Destabilize particles
- Flocculation Grow floc
- Sedimentation Settle solids
- Filtration Remove particles
- Disinfection Inactivate pathogens
- Softening Remove hardness
Infiltration vs Inflow WA
Infiltration
- Groundwater entry
- Cracks/joints
- Slow rise
Inflow
- Direct stormwater
- Roof drains
- Fast spikes
- Groundwater vs stormwater
Wastewater WA
- I/I Unwanted clearwater
- Preliminary Screens/grit
- Primary Settle solids
- Secondary Biological treatment
- F/M Food to biomass
- SRT Sludge age
- Nitrification Ammonia to nitrate
- Denitrification Nitrate to nitrogen
- Dewatering Reduce sludge water
Common Traps
Flow vs load
- Flow is volume/time ≠ Load is mass/time
Peak vs volume
- Peak is maximum rate ≠ Volume is hydrograph area
Major vs minor loss
- Major is pipe length ≠ Minor is fittings
Surcharge vs unit weight
- Surcharge adds surface load ≠ Unit weight acts through depth
Open vs pressurized
- Manning needs free surface ≠ Bernoulli handles pressure energy
BOD vs DO
- BOD consumes oxygen ≠ DO remains available
I/I timing
- Infiltration rises slowly ≠ Inflow spikes quickly
Effluent vs sludge
- Effluent leaves liquid ≠ Sludge carries solids
Last Minute
- 1. Use official handbook only
- 2. Hydrology: Tc drives intensity
- 3. Rational gives peak flow
- 4. NRCS gives runoff depth
- 5. HGL excludes velocity head
- 6. EGL includes velocity head
- 7. Manning needs free surface
- 8. NPSH checks cavitation
- 9. Detention lowers peak
- 10. Retention stores volume
- 11. BOD consumes DO
- 12. Nitrification needs oxygen
- 13. Denitrification needs anoxic zone
- 14. I/I overloads collection
PE Civil: Water Resources and Environmental
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