Project Sitework and Final Review
Key Takeaways
- Project sitework is the single largest WRE knowledge area at 9-14 of 80 questions under the April 2024 NCEES specification.
- Earthwork hinges on volume state: bank, loose, and compacted cubic yards are not interchangeable — shrink reduces compacted volume, swell increases loose volume.
- Erosion and sediment control is both a sitework topic and a water-quality topic because exposed soil becomes downstream pollutant load (SWPPP / NPDES construction permit).
- Site layout, adjacent-facility protection, utility control, work-zone safety, and basic curve geometry are concept checks as much as calculations.
- Retaining-wall and excavation items hinge on lateral earth pressure, surcharge, hydrostatic load behind the wall, drainage, and OSHA trench/sloping rules.
Why Sitework Is Not Filler
The April 2024 WRE specification gives project sitework 9-14 questions, the widest range in the blueprint — more than any single hydraulics topic. Candidates who study only hydrology and hydraulics can fail on sitework alone. The listed topics: excavation and embankment, site layout and control, temporary and permanent erosion and sediment control, impacts on adjacent facilities, safety, basic horizontal and vertical curve elements, retaining walls, and construction methods.
Earthwork And Layout
Earthwork problems are about volume state and constructability. Bank cubic yards (BCY) are in-place natural soil, loose cubic yards (LCY) are excavated/hauled, and compacted cubic yards (CCY) are placed and compacted fill. Swell raises LCY above BCY; shrink drops CCY below BCY. Write the relationship before calculating so you divide when converting compacted fill back to required borrow.
Worked takeoff: a fill needs 12,000 CCY and the borrow yields only 90% of bank volume after compaction, so required borrow = 12,000 / 0.90 ≈ 13,333 BCY. Multiplying instead of dividing (10,800) is the classic trap.
Good grading does three things at once: it produces the required finished surface, routes runoff safely, and avoids damaging adjacent property or utilities. A cut-fill-balanced plan can still be wrong if it ponds water against a structure, sends flow offsite uncontrolled, or leaves a temporary slope unsupported.
| Sitework topic | What to look for | Common wrong turn |
|---|---|---|
| Cut and fill | Volume state, haul, shrink/swell | Mixing compacted and bank quantities |
| Layout control | Benchmarks, limits, utilities, offsets | Treating survey control as paperwork |
| Adjacent facilities | Settlement, vibration, access, drainage | Assuming no impact because work is onsite |
| Work-zone safety | Separation, traffic control, trench hazards | Focusing only on the final condition |
| Curves | Radius, tangents, grade breaks, sight logic | Overcomplicating basic geometry |
| Retaining walls | Earth pressure, surcharge, drainage, water | Ignoring hydrostatic load behind the wall |
Erosion And Sediment Control
Temporary erosion control is a construction-phase water-quality system, typically required by a Stormwater Pollution Prevention Plan (SWPPP) under the NPDES Construction General Permit. The order of operations matters: divert clean run-on around disturbance, stabilize exposed soil quickly, slow runoff before it concentrates, trap sediment near the source, protect inlets/outlets, and maintain controls after each storm. Silt fence is for shallow sheet flow only — it fails in concentrated channel flow. Match the control to the failure mode:
- Sheet flow: silt fence, fiber rolls, perimeter barriers.
- Shallow concentrated flow: check dams, rock-lined swales.
- Channel/outlet energy: riprap, outlet protection, sediment basins.
- Inlets: inlet protection. Site access: stabilized construction entrances.
Permanent controls must match final drainage intent: a swale conveys, a detention basin reduces peak, a retention/infiltration feature reduces volume, and a constructed wetland or forebay provides treatment.
Horizontal And Vertical Curves
Basic curve geometry shows up as concept checks, not lengthy design. For a horizontal curve, the degree of curve, radius, tangent length, and external distance all derive from the deflection angle and radius — a sharper deflection over the same radius lengthens the curve. For a vertical curve, the length L is set by the algebraic grade difference A and a rate K (L = K·A), with sight distance driving K. A crest curve is limited by stopping sight distance over the hump; a sag curve is limited by headlight throw at night.
The WRE trap is overcomplicating these — most items want you to recognize which control governs, not grind a full alignment.
Retaining And Excavation Judgment
Water is the hidden load in retaining-wall items. Free-draining backfill plus weep holes or a drain reduces hydrostatic pressure, but never removes soil self-weight or surcharge from adjacent loads. Active earth pressure increases with backfill unit weight and the active pressure coefficient K_a; the active resultant acts at one-third the wall height from the base. A saturated backfill adds a full hydrostatic triangle and can roughly double the lateral demand, which is exactly why drainage behind the wall is a structural concern, not a nicety. Walls are then checked against sliding, overturning, and bearing failure modes.
Excavation near existing facilities raises settlement, utility, and access risk. OSHA trench rules require a protective system for excavations 5 ft or deeper (sloping, shoring, or shielding), daily inspection by a competent person, spoil set back at least 2 ft from the edge, and a means of egress within 25 ft of workers in trenches 4 ft or deeper. Dewatering, preconstruction condition surveys, vibration monitoring, and sequence planning are risk controls, not administrative extras.
Final Review Process
- Memorize the WRE topic ranges so study time matches question weight.
- Drill unit conversions: BCY/LCY/CCY, MGD, gpm, cfs, acres, ft³, acre-ft.
- Separate water-quality source control from treatment after contamination.
- Review erosion controls by flow type: sheet, shallow concentrated, channel, inlet, outlet.
- Rework every missed sitework problem and name the missed assumption.
- Practice with electronic references only and a clean scratch workflow, timed at ~6.75 min/question.
Exam Strategy
Sitework rewards disciplined reading. Identify the construction phase, the material state, the nearby risk, and the water path before reaching for a formula. If a stem mentions erosion, sediment, drainage, dewatering, or retention, connect it to the water-quality consequences in this chapter — that is the WRE theme: ground-level design choices change loads, flows, safety, and receiving-water performance.
A project needs 12,000 compacted cubic yards of embankment. If the borrow source yields only 90% of its bank volume after compaction, which bank volume is required?
During construction, runoff leaves a disturbed slope as shallow sheet flow before reaching the property line. Which control is most directly matched to that condition?