CSLB C-12 Earthwork and Paving (Trade Exam) — All Questions

Sloping or benching of an excavation more than 20 feet deep must be designed by whom?

• a.The competent person acting alone on site
• b.The registered professional engineer on the project✓
• c.The equipment operator who excavates it
• d.The utility owner whose lines are nearby

Excavations greater than 20 feet deep need sloping or benching designed by a registered professional engineer. The competent person classifies soil and inspects but does not replace the engineer at that depth.8 CCR §1541.1 Appendix B, Table B-1 note 3

A 10-foot-deep Type A trench with a 3-foot bottom width will be open for less than 24 hours. Using the short-term slope, what is the top width?

• a.18 feet
• b.23 feet
• c.33 feet
• d.13 feet✓

Short-term Type A slope for excavations 12 feet or less is 1/2:1, so each side runs 5 feet and the top width is 3 + 5 + 5 = 13 feet. Eighteen feet uses the 3/4:1 slope, 23 feet uses 1:1, and 33 feet uses 1-1/2:1.8 CCR §1541.1 Appendix B, Table B-1 note 2

How often must a competent person inspect an excavation, its adjacent areas and its protective system?

• a.When a Cal/OSHA inspector is expected on site
• b.Once a week, and again after an injury occurs
• c.Daily, as needed during the shift, and after rain✓
• d.Once, when the trench is first opened for work

Inspections are made daily prior to the start of work and as needed throughout the shift, and again after every rainstorm or other hazard-increasing occurrence. A weekly or one-time inspection cannot track changing conditions.8 CCR §1541(k)(1)

A walkway with standard guardrails is required where employees or equipment cross over an excavation of what dimensions?

• a.More than 6 feet deep and more than 30 inches wide✓
• b.More than 4 feet deep and more than 6 feet wide
• c.More than 2 feet deep and wider than 6 inches
• d.More than 20 feet deep and wider than 15 feet

Walkways or bridges with standard guardrails are required for crossing over excavations over 6 feet deep and wider than 30 inches. A depth of 4 feet with a 6-foot width and a depth of 2 feet with a 6-inch width set the trigger at the wrong dimensions, and 20 feet by 15 feet is far too large.8 CCR §1541(l)(1)

Water is accumulating in a trench where a worker is to set pipe. What is required?

• a.Work may continue if the standing water is clear
• b.Waders and rubber boots for the worker
• c.Work may continue if the trench is under 8 feet deep
• d.Water removal or special support before entry✓

Employees may not work in excavations with accumulated or accumulating water unless adequate precautions are taken, such as water removal, special support or a harness and lifeline, and water-removal equipment is monitored by a competent person. Waders and boots keep the worker dry but do not address the cave-in and drowning risks, clear water still saturates the soil and weakens the walls, and a depth under 8 feet does not exempt the trench.8 CCR §1541(h)

A trench shield is installed in a compound excavation. How far must the sides of the shield extend above the vertical walls?

• a.At least 36 inches
• b.At least 24 inches
• c.At least 12 inches
• d.At least 18 inches✓

In compound excavations the shield sides extend a minimum of 18 inches above the vertical walls; on a vertical trench the shield extends to at least the catch point. Thirty-six and 24 inches are higher than the minimum, and 12 inches is lower than the 18 inches stated.8 CCR §1541.1(g)(2)

A trench shield is in place. Under what condition may the contractor excavate up to 2 feet below the bottom of the shield?

• a.If the soil is Type A and the trench is dry
• b.If designed for the full depth and no soil loss is seen✓
• c.If the trench is under 10 feet deep and in Type B soil
• d.If the owner's inspector gives permission on site

Excavating to a level no more than 2 feet below the bottom of a shield is permitted only if the shield is designed for the full-depth forces and there are no indications of a possible loss of soil. Type A soil in a dry trench, a depth under 10 feet in Type B soil, and an inspector's permission do not substitute for that design and the absence of soil loss.8 CCR §1541.1(g)(2)

Where must the upright members of a trench shoring system extend?

• a.To the midpoint, with the lower end on the floor
• b.To the top of the trench, with the lower end 6 feet from the bottom
• c.To 2 feet below the top, with the lower end on the trench floor
• d.To the top, with the lower end within 2 feet of the bottom✓

Uprights extend to the top of the trench and their lower ends may be no more than 2 feet from the bottom of the trench. The other positions would leave the wall unsupported at the top or at the toe.8 CCR §1541.1(h)

How does Cal/OSHA define a trench by width?

• a.An excavation less than 30 inches wide at grade
• b.An excavation that is a narrow cut, not wider than 15 feet at the bottom✓
• c.An excavation not wider than 6 feet at the top
• d.An excavation more than 4 feet deep and wide enough for a machine

A trench is a narrow excavation, generally deeper than wide, whose width measured at the bottom is not greater than 15 feet. A width under 30 inches and a top width of 6 feet are not the definition, and depth with room for a machine describes a wide excavation rather than a trench.8 CCR §1540(b)

A 160-foot trench 6 feet deep uses ladders for egress, and no employee may have more than 25 feet of lateral travel to reach one. What is the minimum number of ladders?

• a.4✓
• b.3
• c.8
• d.6

One ladder serves 25 feet each way, so 50 feet of trench, and 160 ÷ 50 = 3.2, which rounds up to 4 ladders. Three leaves the end gaps too long, and 6 and 8 are more than necessary.8 CCR §1541(c)(2)

A trench is 6 feet deep with a 3-foot bottom width in Type B soil sloped at 1:1. What volume is excavated in a 50-foot length?

• a.About 133 cubic yards
• b.About 2,700 cubic yards
• c.About 33 cubic yards
• d.About 100 cubic yards✓

The top width is 3 + 6 + 6 = 15 feet, the average width is 9 feet, the area is 54 square feet, and 54 × 50 = 2,700 cubic feet = 100 cubic yards. Using the bottom width only gives 33 cubic yards, using a 1-1/2:1 slope gives 133, and 2,700 is the volume in cubic feet.8 CCR §1541.1 Appendix B; estimating practice

A trench runs under a sidewalk. What does Cal/OSHA require before the sidewalk is undermined?

• a.A survey of the sidewalk, since concrete carries itself
• b.Written permission from the pedestrians nearby
• c.A warning sign posted by the sidewalk
• d.A support system or other method of protection✓

Sidewalks, pavements and appurtenant structures may not be undermined unless a support system or another method of protection is provided to protect employees from collapse. A survey assumes concrete carries itself, though undermined concrete can drop; a sign does not hold weight; and pedestrians do not grant permission.8 CCR §1541(i)(3)

A 0.80-foot aggregate base is specified. How is it placed?

• a.One 0.80-foot layer compacted with extra passes
• b.Two layers of 0.50 and 0.30 foot, thick one first
• c.Two roughly equal layers, each no more than 0.50 foot✓
• d.Three 0.27-foot layers

A base thicker than 0.50 foot is spread and compacted in at least two approximately equal layers, and no compacted layer exceeds 0.50 foot, so two 0.40-foot layers satisfy the rule. A single layer is too thick, and the other splits are either unequal or not required.Caltrans 2024 Standard Specifications §26-1.03D

A new embankment is constructed against an existing slope. How is the original slope prepared?

• a.By smoothing it with a grader before the first lift
• b.By leaving it undisturbed so the fill sits on it
• c.By cutting into it at least 6 feet as the fill rises✓
• d.By covering it with fabric to keep the soil in place

The original ground or embankment slope is cut into at least 6 feet horizontally as new embankment is placed in layers, and the cut material is compacted with the new fill (benching). Smoothing creates a slip surface, and fabric or leaving it alone does not key the fill.Caltrans 2024 Standard Specifications §19-6.03A

Clods of earth larger than what size must be broken up before compacting embankment material?

• a.8 inches in greatest dimension✓
• b.3 feet in greatest dimension
• c.24 inches in greatest dimension
• d.2 inches in greatest dimension

Clods or hard lumps over 8 inches in greatest dimension must be broken up before compaction, unless the material cannot be broken readily, in which case it is distributed and surrounded by fine material. Three feet and 24 inches allow clods too large to compact, and 2 inches is smaller than the limit stated.Caltrans 2024 Standard Specifications §19-6.03C

A project has 9,000 bank cubic yards of cut and needs 10,000 compacted cubic yards of fill. The cut shrinks to 0.90 compacted cubic yard per bank cubic yard. How much import, in bank cubic yards, is needed?

• a.About 1,900
• b.About 2,111✓
• c.About 1,000
• d.About 2,500

The cut supplies 9,000 × 0.90 = 8,100 compacted yards, so 1,900 compacted yards are short, and 1,900 ÷ 0.90 = 2,111 bank yards of import. The 1,900 figure leaves out the shrinkage conversion, and 1,000 and 2,500 ignore it entirely.Estimating practice (cut and fill balance); Caltrans 2024 Standard Specifications §19-2.03C

Frozen material is available for a roadway embankment in January. What does the State specification say?

• a.Use thicker layers of the frozen material to compensate
• b.Compact it with extra passes of a vibratory roller
• c.Do not build embankment with frozen material or on snow✓
• d.Place the frozen material in the top 2.5 feet

Embankments are not constructed when the material is frozen or a blanket of snow prevents proper compaction. Thicker layers, extra passes or placement in the critical zone would leave voids and later settlement.Caltrans 2024 Standard Specifications §19-6.03C

A 5,000-square-yard aggregate base is placed in a single layer, with tests at one per 500 square yards on each layer. How many relative compaction tests are required at minimum?

• a.10✓
• b.20
• c.5
• d.50

5,000 ÷ 500 = 10 tests for one layer. Five halves it, and 20 would apply to two layers, and 50 divides by 100.Caltrans 2024 Standard Specifications §26-1.01D(2)(d)

How is earthwork compacted within 150 feet of a bridge abutment?

• a.To 95 percent for the full depth, outer 5 feet excepted✓
• b.To 90 percent through the full width and depth of the embankment
• c.To 95 percent in the top foot of the fill
• d.To 85 percent, at the contractor's choice

The full width and depth of the embankment within 150 feet of each bridge abutment is compacted to at least 95 percent relative compaction, except the outer 5 feet at the side slope. Ninety percent is the lower figure for ordinary embankment, a top-foot-only rule leaves the deeper fill loose beside the abutment, and 85 percent chosen by the contractor is below any stated minimum.Caltrans 2024 Standard Specifications §19-5.03B

A contractor overexcavates below the planned grade in a roadway excavation. What is required?

• a.Backfill with authorized material, compacted✓
• b.Fill with loose spoil and leave it uncompacted
• c.Pay the owner a fee and continue paving
• d.Leave the hole and place base over it as it is

Overexcavation is backfilled with authorized material and compacted. Leaving a void or loose fill under the base creates future settlement, and a fee does not repair it.Caltrans 2024 Standard Specifications §19-2.03A

A 3-foot-thick fill will be built in loose lifts of 8 inches maximum. What is the minimum number of lifts?

• a.4
• b.3
• c.5✓
• d.9

Three feet is 36 inches, and 36 ÷ 8 = 4.5, which rounds up to 5 lifts. Rounding down to 4 would make the lifts thicker than 8 inches, 3 treats feet as lifts, and 9 divides by 4 inches.Caltrans 2024 Standard Specifications §19-6.03C

Where an embankment settlement period is specified, what may not be done before the period ends?

• a.Survey the settling embankment for movement
• b.Excavate for abutment footings or drive piles✓
• c.Water the embankment to control dust
• d.Place pavement on roadways away from the settling fill

Before the end of the settlement period the contractor may not excavate for abutments, bent footings, wingwalls or retaining wall footings, or drive or drill foundation piles in the settling embankment. Other work elsewhere, surveying and watering are not prohibited.Caltrans 2024 Standard Specifications §19-6.03D

Loose rocks larger than what size are removed from a slope before cultivation or straw incorporation?

• a.6 inches in maximum dimension
• b.2-1/2 inches in maximum dimension✓
• c.12 inches in maximum dimension
• d.1-1/2 inches in maximum dimension

Before cultivation or straw incorporation, loose rocks larger than 2-1/2 inches in maximum dimension, roots and debris are removed from the slope surface. Six and 12 inches are larger than the stated size, and 1-1/2 inches is smaller than it.Caltrans 2024 Standard Specifications §19-2.03G