Free PE Civil: Water Resources and Environmental exam Practice Questions

Sample Practice Questions

Try these 10 sample questions from the PE Civil: Water Resources and Environmental exam practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A cost engineer receives a pump-station quantity takeoff prepared by a separate design consultant. Under USACE quantity-development guidance, who remains responsible for ensuring that the quantities have a traceable, defensible basis suitable for independent review?

   1. A. The construction contracting officer
   2. B. The project cost engineer
   3. C. The project funding sponsor
   4. D. The construction field superintendent

   Answer: B

   Explanation: USACE states, "Regardless of the source, the cost engineer must ensure quantities are supported by a defensible, documented source that reflects the project scope and design level that is traceable and can reasonably support an independent quality review." The outside consultant's preparation does not transfer the cost engineer's duty to establish a reviewable quantity basis. The other project roles do not replace the expressly named responsible engineer.

   Reference: Civil Works Cost Engineering, ER 1110-2-1302 — Section 11, p. 14

2. 2A 6-m-high smooth vertical retaining wall yields sufficiently to mobilize active pressure in level, dry cohesionless backfill. The unit weight is 18 kN/m³ and the active coefficient is 1/3. With no surcharge, what is the total horizontal soil force per meter of wall?

   1. A. 36 kN/m
   2. B. 108 kN/m
   3. C. 216 kN/m
   4. D. 324 kN/m

   Answer: B

   Explanation: FHWA gives "Active force within depth z: Pa = Ka γ z2/2". Integrating the triangular active-pressure distribution gives Pa = (1/3)(18)(6²)/2 = 108 kN/m. Using the base pressure as the force gives 36; omitting the triangular factor gives 216; omitting Ka gives 324.

   Reference: Soils and Foundations Reference Manual, Volume I — Printed page 2-46, active-force expression in the pressure-distribution illustration

3. 3An inorganic soil has 65% passing the No. 200 sieve, liquid limit 60, and plasticity index 35. The plasticity point lies above the A-line. Which fine-grained classification describes this soil?

   1. A. Low-plasticity silt
   2. B. Low-plasticity clay
   3. C. High-plasticity clay
   4. D. High-plasticity silt

   Answer: C

   Explanation: FHWA states, "The A-line generally separates soils whose behavior is more claylike (points plotting above the A-Line) from those that exhibit a behavior more characteristic of silt (points plotting below the A-line)." It also states, "The LL = 50 line generally represents the dividing line between silt, clay and organic fractions of the soil that exhibit low plasticity (LL<50) and high plasticity (LL>50)." The fine-grained inorganic sample is claylike above the A-line, and LL60 makes it high-plasticity clay. The other choices reverse one or both classifications.

   Reference: Soils and Foundations Reference Manual, Volume I — Sections 4.2.1.2 and 5.3.5.1, Classification of Fine-Grained Soils and Plasticity Chart

4. 4Water flows steadily through a full pipe that expands from 0.20 m to 0.40 m in diameter, with no branches or leakage. If inlet mean velocity is 4.0 m/s, what is outlet mean velocity?

   1. A. 2.0 m/s
   2. B. 8.0 m/s
   3. C. 1.0 m/s
   4. D. 16.0 m/s

   Answer: C

   Explanation: DOE gives "(ρAv)inlet = (ρAv)outlet". Constant density makes velocity inversely proportional to area: v₂ = 4(0.20/0.40)² = 1 m/s. The distractors use a linear diameter ratio, reverse that linear ratio, or reverse the area ratio.

   Reference: DOE Fundamentals Handbook: Thermodynamics, Heat Transfer, and Fluid Flow, Volume 3 — Continuity Equation, equation 3-5, p. 11

5. 5A rectangular drainage channel is 4 m wide and carries water 1 m deep. What hydraulic radius should be used for its wetted section?

   1. A. 1.000 m
   2. B. 0.400 m
   3. C. 0.333 m
   4. D. 0.667 m

   Answer: D

   Explanation: FHWA defines hydraulic radius by "dividing the flow area by the length of the cross section in contact with the water (wetted perimeter)." Thus R = 4/(4+2×1) = 0.667 m. Other choices use top width, include the free surface in the perimeter, or double the wetted perimeter.

   Reference: Introduction to Highway Hydraulics, Hydraulic Design Series No. 4 — Glossary, Hydraulic Radius

6. 6For detention routing, an engineer plots rainfall intensity against time in successive storm intervals. What is this representation called?

   1. A. A rainfall hyetograph
   2. B. A mass rainfall curve
   3. C. A discharge hydrograph
   4. D. An intensity-duration-frequency curve

   Answer: A

   Explanation: FHWA states, "The designer then plots these results as a rainfall hyetograph" after determining intensity for storm intervals. A mass curve accumulates rainfall, a hydrograph shows flow, and an IDF curve describes frequency and duration rather than one event's time sequence.

   Reference: Urban Drainage Design — Section 4.1.2, p. 21

7. 7A tightly cased well taps a confined aquifer whose top is at elevation 80 m. Water rises in the well to elevation 90 m, while land surface is at 95 m. Which description applies?

   1. A. A flowing artesian well
   2. B. A water-table well
   3. C. A nonflowing artesian well
   4. D. A perched water-table well

   Answer: C

   Explanation: USGS states, "The water level in artesian wells stands at some height above the top of the aquifer but not necessarily above the land surface". The water rises above the confined aquifer but remains below land, so the well is artesian without flowing at the surface.

   Reference: Basic Ground-Water Hydrology — Aquifers and Confining Beds, p. 6

8. 8A distribution-main design includes a bend with unrestrained joints. What provision addresses the hydraulic thrust that could move this fitting?

   1. A. Reaction blocking or appropriately designed joint restraint
   2. B. An air-release valve or appropriately sized vacuum breaker
   3. C. A pressure gauge or appropriately ranged pressure transmitter
   4. D. A drain valve or appropriately sized flushing connection

   Answer: A

   Explanation: The specified water-works standard states, "All tees, bends, plugs and hydrants shall be provided with reaction blocking, tie rods or joints designed to prevent movement." These resist thrust mechanically. Air valves, instrumentation, and drain connections perform other distribution functions without providing thrust restraint.

   Reference: Recommended Standards for Water Works, 2018 Edition — Section 8.7.4, Blocking

9. 9During a dry-weather sewer investigation, an engineer observes groundwater entering a cracked sewer pipe from the surrounding soil. Which term identifies this unwanted contribution?

   1. A. Infiltration
   2. B. Inflow
   3. C. Exfiltration
   4. D. Industrial discharge

   Answer: A

   Explanation: EPA includes in infiltration the "passing of water from the soil into a pipe, such as a sewer." The observed entry through a crack is infiltration, rather than surface-water inflow, outward leakage, or an intentional wastewater discharge.

   Reference: Primer for Municipal Wastewater Treatment Systems — Common Wastewater Treatment Terminology, Infiltration

10. 10Two consecutive excavation cross sections have cut areas of 20 m² and 40 m² and are 30 m apart on a straight alignment. Using the average end-area method, what is the intervening cut volume?

    1. A. 300 m³
    2. B. 600 m³
    3. C. 900 m³
    4. D. 1,800 m³

    Answer: C

    Explanation: FHWA describes the cross section as "the mean of the two end areas". Thus V = 30(20 + 40)/2 = 900 m³. The other results use the area difference, only the first area, or the sum without averaging.

    Reference: Earthwork Design—Project Development and Design Manual Guidance — Determination of Excavation and Embankment Volumes