LARE LARE Grading and Earthwork 2 — Questions and Answers
Question 1: The average end area method is used to calculate earthwork volumes. If Station 0+00 has an end area of 120 sq ft and Station 1+00 has an end area of 200 sq ft, what is the volume in cubic yards?
- 593 CY (Correct answer)
- 889 CY
- 1,185 CY
- 481 CY
Correct answer: 593 CY
Volume = ((120 + 200) / 2) × 100 ft = 16,000 cu ft ÷ 27 = 592.6, approximately 593 CY.
Question 2: When reading a grading plan, a contour line that forms a 'V' shape pointing uphill indicates which topographic feature?
- A ridge
- A valley or swale (Correct answer)
- A plateau
- A cliff face
Correct answer: A valley or swale
Contour V-shapes pointing uphill indicate a valley, drainage swale, or stream channel where water flows.
Question 3: A landscape architect must grade a parking lot so it drains properly. What is the minimum recommended slope for paved surfaces to ensure positive drainage?
- 0.25% (Correct answer)
- 1.0%
- 2.0%
- 5.0%
Correct answer: 0.25%
A minimum slope of 0.25% (1/4 of 1%) is generally accepted for paved surfaces to achieve positive drainage.
Question 4: Which of the following soil classifications has the greatest swell factor when excavated, requiring the most adjustment in earthwork calculations?
- Sandy loam
- Clay
- Rock (Correct answer)
- Silty sand
Correct answer: Rock
Rock has the highest swell factor (up to 30–40%) because blasting and fracturing dramatically increases its volume compared to in-place conditions.
Question 5: On a grading plan, a designer places a spot elevation of 102.5 at a low point in a parking lot. The nearest catch basin rim elevation is 102.0. This condition will result in:
- Proper drainage toward the catch basin
- Ponding water at the low point (Correct answer)
- Overflow toward adjacent streets
- Accelerated erosion
Correct answer: Ponding water at the low point
If the low point spot elevation (102.5) is higher than the catch basin rim (102.0), water cannot flow into the basin and will pond at the low point.
Question 6: A retaining wall is needed where a grade change of 6 feet occurs over a horizontal distance of 8 feet. What is the slope of the retained bank?
- 0.75:1 (H:V)
- 1.33:1 (H:V) (Correct answer)
- 0.48:1 (H:V)
- 2.0:1 (H:V)
Correct answer: 1.33:1 (H:V)
Slope expressed as H:V = horizontal ÷ vertical = 8 ÷ 6 = 1.33:1, meaning for every 1.33 feet of horizontal run there is 1 foot of rise.
Question 7: During earthwork operations, a shrinkage factor of 0.85 means that:
- 15% more material must be borrowed to achieve the compacted volume needed (Correct answer)
- Excavated material will expand 15% when placed
- The soil loses 15% of its moisture during grading
- 15% of the material will be wasted during transport
Correct answer: 15% more material must be borrowed to achieve the compacted volume needed
A shrinkage factor of 0.85 means compacted fill occupies only 85% of its bank volume, so 15% more material must be imported to yield the required compacted volume.
LARE LARE Grading and Earthwork 2
The average end area method is used to calculate earthwork volumes.
If Station 0+00 has an end area of 120 sq ft and Station 1+00 has an end area of 200 sq ft, what is the volume in cubic yards?