ASPE CPD STUDY GUIDE ANSWERS AND QUESTIONS
SET A+
✔✔What is the maximum total movement that should be absorbed by any expansion
loop or offset? - ✔✔1-1/2 inches.
✔✔What two methods are usually employed to absorb pipe expansion or contraction
without danger to the piping? - ✔✔"1. Expansion loops and offsets 2. Expansion joints"
✔✔When piping cannot move freely, where does failure due to thermal expansion and
contraction usually occur? - ✔✔At the pipe joints and fittings, as the pipe itself can
usually withstand these stresses.
✔✔If piping is restrained from moving, it will be subjected to what kind of stresses? -
✔✔Compressive stress on a temperature rise, and tensile stress on a temperature drop.
✔✔Define ‚ÄúCoefficient of Expansion‚Äù - ✔✔The unit increase in length of a material
per 1 degree F increase in temperature
✔✔What type of pipe is not acceptable for storm sewers and why? - ✔✔Vitrified tile pipe
because it is brittle and weak in larger diameters.
✔✔What are typical pipe types used for different areas of storm sewers? - ✔✔For
building connections Between the building sewer and the first downstream structure,
cast iron soil pipe is recommended. This pipe will better withstand shock loads from
materials and equipment likely to be encountered within close vicinity of buildings, and
has a large variety of fittings available. Reinforced concrete pipe is most satisfactory for
general use elsewhere, and is often not readily available in sizes under 12 inches. PVC
may also be used. Check the code.
✔✔Name three types of drainage structures (for site drainage) - ✔✔Manholes: used
where no surface water enters the system Drain inlets: used in any point in paved areas
, where surface water enters the sewers Catch basins: which are similar to drain inlets
but are located in grassy or unimproved areas.
✔✔When designing site drainage, how is the equivalent area calculated? - ✔✔The
equivalent drainage area of each inlet and building connection is taken into account.
The equivalent area is the product of the actual area in acres times the runoff
coefficient, C. The runoff coefficient is based on the absorption capabilities and the
surface roughness characteristics of the surface across which the water will drain.
✔✔What are the four rules for hydraulic design, ensuring the establishment of the exact
size, slope, and invert of all sewer pipes? - ✔✔"1. Slopes should provide a minimum
velocity of 2.5 fps under design conditions to prevent deposition within the pipe during
periods of peak flow. 2. Cover over piping will vary. Verify structural ability of the piping
material to carry loads. 3. Sufficient change in pipe invert should be allowed at
structures to provide for hydraulic losses occurring at these points. 4. Where changes in
pipe size occur, pipe should be laid crown to crown to avoid surcharge of the upstream
pipe."
✔✔What is the time of concentration in a storm sewer system? - ✔✔The sum of the
inlet time at the upper most inlet plus the time of flow in the pipe using the average
slope of the site.
✔✔What is ‚Äúthe time of concentration?‚Äù - ✔✔The time it takes for the entire area to
start contributing to the flow at a given point. The time of concentration for an inlet is
time it takes for rainfall to accumulate and flow over the ground to the inlet (sometimes
called “inlet time.”)
✔✔In terms of storm water, what is the ‚ÄúRational Method‚Äù used for? - ✔✔To
determine the amount of runoff created in a storm.
✔✔When there are no unusual conditions or requirements, what design frequency (or
‚Äúreturn period‚Äù) should be used for an average site? - ✔✔10 years, 15 at most.
Beyond that consider other measures such as dikes or emergency pumps.
✔✔Are site drainage slope requirements steeper or shallower than building plumbing
slope requirements? - ✔✔Shallower.
✔✔Why are preliminary investigations of site drainage systems so important? - ✔✔They
could affect site grades, building elevation, possible unforeseen costs, and the
additional loading of the municipal sewer system, which may already be overtaxed.
✔✔Name some unknown and unknowable factors that can complicate site drainage
design - ✔✔The exact amount of rainfall is never known, a hypothetical design storm is
used, hydraulic conditions at discharge points are extremely variable, the percentage of
SET A+
✔✔What is the maximum total movement that should be absorbed by any expansion
loop or offset? - ✔✔1-1/2 inches.
✔✔What two methods are usually employed to absorb pipe expansion or contraction
without danger to the piping? - ✔✔"1. Expansion loops and offsets 2. Expansion joints"
✔✔When piping cannot move freely, where does failure due to thermal expansion and
contraction usually occur? - ✔✔At the pipe joints and fittings, as the pipe itself can
usually withstand these stresses.
✔✔If piping is restrained from moving, it will be subjected to what kind of stresses? -
✔✔Compressive stress on a temperature rise, and tensile stress on a temperature drop.
✔✔Define ‚ÄúCoefficient of Expansion‚Äù - ✔✔The unit increase in length of a material
per 1 degree F increase in temperature
✔✔What type of pipe is not acceptable for storm sewers and why? - ✔✔Vitrified tile pipe
because it is brittle and weak in larger diameters.
✔✔What are typical pipe types used for different areas of storm sewers? - ✔✔For
building connections Between the building sewer and the first downstream structure,
cast iron soil pipe is recommended. This pipe will better withstand shock loads from
materials and equipment likely to be encountered within close vicinity of buildings, and
has a large variety of fittings available. Reinforced concrete pipe is most satisfactory for
general use elsewhere, and is often not readily available in sizes under 12 inches. PVC
may also be used. Check the code.
✔✔Name three types of drainage structures (for site drainage) - ✔✔Manholes: used
where no surface water enters the system Drain inlets: used in any point in paved areas
, where surface water enters the sewers Catch basins: which are similar to drain inlets
but are located in grassy or unimproved areas.
✔✔When designing site drainage, how is the equivalent area calculated? - ✔✔The
equivalent drainage area of each inlet and building connection is taken into account.
The equivalent area is the product of the actual area in acres times the runoff
coefficient, C. The runoff coefficient is based on the absorption capabilities and the
surface roughness characteristics of the surface across which the water will drain.
✔✔What are the four rules for hydraulic design, ensuring the establishment of the exact
size, slope, and invert of all sewer pipes? - ✔✔"1. Slopes should provide a minimum
velocity of 2.5 fps under design conditions to prevent deposition within the pipe during
periods of peak flow. 2. Cover over piping will vary. Verify structural ability of the piping
material to carry loads. 3. Sufficient change in pipe invert should be allowed at
structures to provide for hydraulic losses occurring at these points. 4. Where changes in
pipe size occur, pipe should be laid crown to crown to avoid surcharge of the upstream
pipe."
✔✔What is the time of concentration in a storm sewer system? - ✔✔The sum of the
inlet time at the upper most inlet plus the time of flow in the pipe using the average
slope of the site.
✔✔What is ‚Äúthe time of concentration?‚Äù - ✔✔The time it takes for the entire area to
start contributing to the flow at a given point. The time of concentration for an inlet is
time it takes for rainfall to accumulate and flow over the ground to the inlet (sometimes
called “inlet time.”)
✔✔In terms of storm water, what is the ‚ÄúRational Method‚Äù used for? - ✔✔To
determine the amount of runoff created in a storm.
✔✔When there are no unusual conditions or requirements, what design frequency (or
‚Äúreturn period‚Äù) should be used for an average site? - ✔✔10 years, 15 at most.
Beyond that consider other measures such as dikes or emergency pumps.
✔✔Are site drainage slope requirements steeper or shallower than building plumbing
slope requirements? - ✔✔Shallower.
✔✔Why are preliminary investigations of site drainage systems so important? - ✔✔They
could affect site grades, building elevation, possible unforeseen costs, and the
additional loading of the municipal sewer system, which may already be overtaxed.
✔✔Name some unknown and unknowable factors that can complicate site drainage
design - ✔✔The exact amount of rainfall is never known, a hypothetical design storm is
used, hydraulic conditions at discharge points are extremely variable, the percentage of
