Alabama Water Projects Contractor Examination

Under OSHA 29 CFR 1926 Subpart P, when must a trench generally have a protective system such as sloping, shoring, or a trench box?

• AOnly when the trench is deeper than 20 feet
• BOnly when groundwater is visible in the invert
• CAt 5 feet or deeper unless a competent person finds no indication of a potential cave-in…
• DOnly on nights and weekends

A water-main trench will be 6 feet deep. At what depth must a stairway, ladder, ramp, or other safe means of egress be provided?

• AOnly if the trench exceeds 10 feet
• BIn trenches 4 feet or more in depth
• COnly in trenches that are also classified as permit-required confined spaces
• DEgress is never required if a trench box is used

In a 4-foot-or-deeper water trench, how far may a worker have to travel laterally to reach a ladder or other required egress?

• ANo more than 25 feet
• BNo more than 50 feet
• CNo more than 100 feet
• DAny distance is acceptable if a radio is on site

Where must excavated spoil be placed relative to the edge of a water-main trench?

• APiled against the trench wall to act as a surcharge berm
• BDumped back into the trench as soon as the pipe is set, even if workers remain inside
• CCentered over the pipe alignment so it can be used as a walkway
• DAt least 2 feet from the edge of the excavation, or retained by devices that keep materia…

For a simple slope in Type A soil less than 20 feet deep, what maximum slope does OSHA Subpart P Appendix B allow?

• AVertical (1/2 horizontal to 1 vertical)
• B3/4 horizontal to 1 vertical (53 degrees)
• C1 horizontal to 1 vertical (45 degrees)
• D1 1/2 horizontal to 1 vertical (34 degrees)

A water trench in Type C soil will be 8 feet deep and less than 20 feet. What simple slope must not be exceeded?

• AVertical cut with no bench
• B3/4 horizontal to 1 vertical
• C1 1/2 horizontal to 1 vertical (34 degrees)
• D1/4 horizontal to 1 vertical

When must a competent person inspect a water-project excavation?

• ADaily, before each shift, and after every rainstorm or other hazard-increasing occurrence
• BOnly on the first day the trench is opened
• COnly if a cave-in has already occurred
• DOnce per month if no one has been injured

A cohesive soil tests at 1.6 tons per square foot unconfined compressive strength, but the trench is next to a vibrating compactor and the soil was previously excavated for an old main. How should it be classified for OSHA sloping?

• AType A, because the strength exceeds 1.5 tsf
• BStable rock, because it is cohesive
• CType A if the contractor prefers a steeper slope
• DNot Type A; fissuring, vibration, previous disturbance, or seepage disqualify Type A rega…

Before workers enter a water excavation more than 4 feet deep where an oxygen deficiency or hazardous atmosphere could reasonably be expected, what must be done?

• AIssue dust masks and continue
• BTest the atmosphere before employees enter
• CWait 10 minutes with no testing if the trench is open to the sky
• DTest only if a worker already feels dizzy

OSHA treats an atmosphere as oxygen-deficient when the oxygen concentration is below what level?

• A23.5 percent
• B21.0 percent
• C19.5 percent
• D16.0 percent

If flammable gas may be present in a water-project excavation, exposure must be prevented above what concentration?

• A20 percent of the lower flammable limit (LFL)
• B100 percent of the lower flammable limit
• CThe upper explosive limit only
• DAny reading below 50 percent methane by volume is acceptable

Which practice is required around lifting equipment and public traffic on a water-main job?

• AStand under the suspended pipe to guide the joint by hand
• BWear dark clothing in the travel lane so drivers are not distracted
• CAllow the excavator to swing loads over the trench while pipelayers work in the box
• DKeep employees out from under loads, and use high-visibility apparel when exposed to publ…

In wet-mix shotcrete, when is water combined with the other ingredients?

• AWater is withheld until the material has already bounced off the receiving surface
• BIngredients are mixed with water before the mixture is delivered to the nozzle
• CWater is added only after the shotcrete has been in place for 24 hours
• DWet-mix shotcrete uses no water at any stage

How does dry-mix shotcrete differ from wet-mix at the point of application?

• ADry-mix is always pumped as a fully hydrated slurry from the plant
• BDry-mix uses no cement
• CWater is added at the nozzle as the dry ingredients are projected
• DDry-mix can only be used underwater

What should be done with rebound from structural shotcrete on a water tank or basin wall?

• ADiscard it; rebound is not part of the in-place section and must not be reused in structu…
• BShovel it back into the next layer to reduce waste
• CBlend it 50/50 with fresh mix at the gun
• DUse it as the finish coat because it is richer in cement

Why is a qualified nozzleman essential on structural shotcrete for water-retaining work?

• AThe nozzleman only starts and stops the compressor
• BAny laborer can hold the nozzle if the mix design is correct
• CQualification is required only for decorative rock work
• DThe nozzleman controls thickness, consolidation, embedding of reinforcement, and rebound

Immediately before applying shotcrete to a tank wall or repair area, the receiving surface should be:

• ACovered with a film of form oil so the shotcrete does not bond
• BClean, sound, and properly prepared, with loose material, laitance, and rebound removed
• CLeft dusty so the first layer can key into the powder
• DFrozen so the shotcrete sets faster

When building a thick shotcrete section on a water basin wall, what layering practice is required?

• APlace the full thickness in one pass even if rebound piles against the reinforcement
• BLeave sand lenses in place as drainage layers
• CBuild up in layers as needed and do not trap rebound or sand lenses between layers
• DStop each layer with a cold, dusty, unprepared joint

How must reinforcement be treated during structural shotcrete placement?

• AEncapsulate the bars with shotcrete so they do not vibrate independently and so specified…
• BLeave a shadow void behind each bar to save material
• CAllow bars to rattle in the stream because vibration consolidates the mix
• DHold bars by hand in the live stream to keep them aligned

After shotcrete is placed on a water-retaining wall, which statement about curing is correct?

• ACuring is optional if the mix looked wet at the nozzle
• BCuring is needed only for decorative finishes
• CShotcrete should be allowed to freeze the first night to gain strength faster
• DCuring is required, and the work must be protected from freezing and from rapid drying

Which pair of factors most directly affects in-place shotcrete quality at the wall?

• AThe color of the compressor and the brand of hose fittings
• BWater-cementitious materials ratio and velocity of the material at the nozzle
• COnly the ambient humidity, regardless of mix or application
• DThe time of day the ready-mix plant opened

Before placing the next lift of shotcrete on a partially completed tank wall, the crew should:

• AWet the rebound in place and shoot over it
• BScarify only the top inch and leave loose sand against the bars
• CRemove loose material and rebound from the previous layer so the new shotcrete bonds to s…
• DCover the wall with polyethylene and shoot through the plastic

What is the standard conversion used to estimate concrete volume in cubic yards from dimensions in feet?

• ACubic yards = length × width × thickness (feet) ÷ 27
• BCubic yards = length × width × thickness (feet) × 27
• CCubic yards = length × width only, ignoring thickness
• DCubic yards = thickness in inches divided by 12

A rectangular clearwell floor is 40 feet long, 30 feet wide, and 6 inches thick. How many cubic yards of concrete are required for the floor?

• A6.7 cubic yards
• B13.3 cubic yards
• C22.2 cubic yards
• D600 cubic yards

A waterstop is detailed in the construction joint of a tank wall. How must it be installed?

• AContinuous through the joint, held in the detailed position, with splices made by the man…
• BCut into short pieces and dropped loose into the joint before the pour
• CFolded flat against one form face so it does not get in the way of the vibrator
• DNailed through the center bulb every 12 inches to hold it in place

A circular tank floor is 24 feet in diameter and 8 inches thick. Using π = 3.14, what is the neat concrete volume to the nearest 0.1 cubic yard?

• A4.5 cubic yards
• B8.0 cubic yards
• C37.7 cubic yards
• D11.2 cubic yards

For water-retaining concrete, why is the water-cementitious materials ratio so important?

• AIt is the primary driver of paste permeability and therefore of leakage and durability
• BIt only affects the color of the finished wall
• CA higher ratio always makes concrete more watertight
• DIt has no effect if the slump is 4 inches

On a hot, windy Alabama afternoon, a tank floor begins to show early surface cracks while the concrete is still plastic. What is the most likely cause and a proper response?

• AThe cracks are form-tie holes and should be ignored
• BThe mix has too little water and more water should be added on the slab
• CRapid evaporation is causing plastic shrinkage; cool materials, fog, and specified retard…
• DPlastic cracks mean the concrete is already at design strength

During cold weather, newly placed tank concrete must be:

• AFlooded with ice water to speed set
• BProtected from freezing until it has gained adequate specified strength
• CLeft uncovered so it can freeze and thaw each night
• DMixed with extra water so it cannot freeze

What is the purpose of consolidating structural concrete with an internal vibrator on a water tank wall?

• ATo add extra mixing water at the face
• BTo create as many large air pockets as possible for drainage
• CTo lift the reinforcement out of the forms
• DTo release trapped air and embed the reinforcement without leaving voids

A finisher holds a vibrator in one spot in a tank wall until a large slurry patch appears and coarse aggregate has sunk away. What is the problem?

• AOver-vibration is causing segregation, which leaves a weak, permeable paste layer
• BThe wall is now as watertight as it can be
• CSegregation only occurs in shotcrete, never in formed concrete
• DThe slurry patch proves the water-cementitious ratio was too low

Compared with ordinary building concrete, water-retaining tank concrete is typically specified with:

• AAs much mixing water as the pump will take
• BNo limit on permeability
• CA lower water-cementitious materials ratio to reduce permeability
• DNo curing, because tanks will later be filled with water

The pump operator wants to add water at the jobsite so a tank-wall mix will pump easier. What is the correct practice?

• AAdd any amount of water if the slump looks stiff
• BDo not add water beyond the specified mixture limits; use approved admixtures or mixture…
• CAdd water only to the last 2 cubic yards in the load
• DAdd water, then add extra cement by the shovelful to compensate

A rectangular tank wall is 50 feet long, 10 feet high, and 10 inches thick. What is the neat concrete volume?

• A4.6 cubic yards
• B10.0 cubic yards
• C18.5 cubic yards
• D15.4 cubic yards

Groundwater at a new ground-storage tank site has a high sulfate content. Under ASTM C150, which portland cement type is specified when high sulfate resistance is required?

• AType III
• BType I
• CType IV
• DType V

Which hot-weather controls are appropriate when placing a large tank floor?

• ACool materials, plan for rapid placement, fog the surface, and use specified retarders if…
• BDry the aggregates in the sun to raise mix temperature
• CPlace only at midday when evaporation is highest
• DSkip curing because heat will harden the slab faster

How many cubic feet are in 1 cubic yard of concrete?

• A9
• B12
• C27
• D36

A 6-inch mud mat will be placed under a tank footing area 40 feet by 20 feet. How many cubic yards of concrete are required?

• A4.4 cubic yards
• B8.9 cubic yards
• C40 cubic yards
• D14.8 cubic yards

What is the nominal unit weight of a #4 reinforcing bar?

• A0.250 pounds per foot
• B0.668 pounds per foot
• C1.043 pounds per foot
• D1.502 pounds per foot

Bars delivered for a tank wall carry rolled-in markings. Under the ASTM marking system described by CRSI, what do those marks identify?

• AOnly the truck route and the delivery date
• BThe producing mill, the bar size, the type of steel, and the grade
• CThe lap-splice length required by the drawings
• DThe concrete strength the bar may be embedded in

Thirty #6 bars, each 20 feet long, will be placed in a tank footing. Using 1.502 pounds per foot, what is the steel weight?

• A901 pounds
• B668 pounds
• C601 pounds
• D1,502 pounds

How should reinforcing bars be supported to maintain specified cover in a tank floor?

• AOn loose scrap wood that will rot after the pour
• BOn random bricks scavenged from demolition
• CBy laying the bars directly on the subgrade
• DOn chairs, dobies, or other supports approved to hold the specified cover

Workers need to cross a placed tank-floor bar mat to reach a bulkhead. What is the correct practice?

• AWalk on the bars; they are stiff enough
• BUse planks or walkways so the bars are not displaced
• CJump from bar to bar to keep contact time short
• DRemove a strip of bars as a path and replace them after the pour

Why is specified concrete cover over reinforcement especially critical in a potable-water tank?

• ACover is only an appearance item for the inspector
• BExtra-thin cover makes the wall more flexible and therefore more watertight
• CCover protects the steel from moisture and helps the section remain durable and leak-resi…
• DCover may be omitted wherever a waterstop is used

A footing requires 500 linear feet of #4 bar. Using 0.668 pounds per foot, what is the steel weight?

• A334 pounds
• B500 pounds
• C668 pounds
• D1,043 pounds