CPD ASPE Study Questions AH with
Complete Solutions48
What is the design criterion for storm water sizing? - ANSWERS-The required rate of discharge
from any collection area, dependent on the size of the area, and the maximum rate of rainfall
per hour.
Why is condensation a concern for roof drainage and how can it be overcome? - ANSWERS-Low
temperature liquid flow in storm water piping will cause condensation to form on piping inside
the building. Insulation of pipes and roof drain bodies will keep the condensation from dripping
onto the ceiling or floor.
The connection to roof drains should always use what? - ANSWERS-An expansion joint, either
integral or separate. This prevents the pipe expansion and contraction (from severe outdoor
temperature swings and a fairly constant inside temperature) from raising the roof drain and
destroying the integrity of the water proofing at the roof.
If the storm piping is run separately from the sanitary piping, how many traps are required
before connection to the sanitary system or combined sewer? - ANSWERS-One.
What is different about storm water drainage system design? - ANSWERS-Design of a storm
drainage system is based on the piping flowing full under uniform flow conditions. Downspouts
(also called conductors or leaders) and horizontal piping can also flow full as maintaining
hydraulic pressures within any fixed limits in the system is not necessary as it is in a sanitary
drainage system.
Define Stormwater: - ANSWERS-Rainwater, surface runoff, ground water, subsurface water, or
similar clear liquid wastes, exclusive of sewage, condensate, and industrial waste
,What does the Manning Formula describe? - ANSWERS-The velocity of uniform flow in sloping
drains.
Front - ANSWERS-Back
What is the specific weight of water? - ANSWERS-62.4 lbs per cubic foot
What happens in a storm and sanitary system after it passes the water test? - ANSWERS-A
smoke pressure test is recommended with a smoke pressure of 1 in wc to prove the system gas
tight.
Is an air test acceptable for a storm and sanitary system? - ANSWERS-Yes, if a water test is not
possible, at a pressure of 5 psi, are tests are impractical and costly
What are the testing procedures for the storm and sanitary system? - ANSWERS-A water test
upon completion of the rough piping and prior to concealment of 10 ft wc minimum (except the
topmost 10 feet of pipe), not to exceed 100 ft wc. If system is higher than 100 feet, test plugs
must be installed to facilitate testing, rarely are more than 7 stories tested at one time. A
peppermint oil test may also be done with 2 oz of peppermint oil and 10 qt boiling water, and
searching for peppermint smell at leaks, however it is difficult to pinpoint the leak by this
method
The maximum length from the vent connection to any future drain outlet is required by code,
why, how long is the distance (listed in the book), and what’s the exception? - ANSWERS-To
prevent a dead end where slime, sludge and fungi can grow, 2 feet, unless the piping must be
extended to an accessible location for a cleanout
A sanitary tee may be used in the vertical but what may not be used in the vertical and why? -
ANSWERS-A double sanitary tee because the possibility of flow crossover and excessive
pressures when one branch is discharging and the other isn’t are possible
,What are the slopes of pipe inside the building that correspond to 2 fps velocity? - ANSWERS-
1/4 in per foot for 3 in and smaller 1/8 in per foot for larger pipe all elbows, taps, tees etc are
tapped at a pitch of 1/4” per foot
Where should cleanouts be provided? - ANSWERS-1) Inside or outside the building at the point
of exit (use a wye branch) 2) at every change in direction greater than 45 degrees 3) every 50
feet for piping 4” and less, and 100 ft for larger piping 4) underground piping larger than 10 in
should be provided with manholes at every change in direction and every 150 feet 5) at the
base of all stacks 6) as required by code
What size cleanouts are provided in piping? - ANSWERS-Piping up to 4 inches, the cleanout is
the same size as the pipe. Piping greater than 4 inches, 4 inch cleanouts are adequate.
What should be installed in the house drain if there is a danger of backflow of sewage into the
building? Whats the difference? - ANSWERS-A backwater valve or a combination BWV with
manually operated gate valve. The BWV does not interfere with the airflow throughout the
system, and the gate valve is recommended where there is a history of backflow as a positive
means of protection.
Branch connections to the house drain should be made where and why? - ANSWERS-At the
upper portion of the pipe (above the 1/2 - 2/3 full mark) because: 1) there is a lower chance of
stoppages in the branch 2) there is less flow interference at the point of connection 3) When
there is no flow in the branch, the full area of the pipe is available to relieve pneumatic pressure
fluctuations in the house drain
How many fixture units are equivalent to 1 gpm continuous or semicontinuous flow and what
are examples of these types of flow? - ANSWERS-2 FUs, sump pumps, ejectors, air conditioning
equipment, water cooled, equipment, etc
What minimum slopes are required for building drains and why? - ANSWERS-3 in pipe and
smaller: 1/4 in/ft 4-6 in pipe: 1/8 in/ft 8 in pipe and larger: 1/16 in/ft to maintain 2 fps scouring
action if low flow fixtures are present, 1/4 in/ft for all is a good idea
, House drains are designed to flow how full? - ANSWERS-1/2 full to 3/4 full max under uniform
flow conditions
What is a house (building) drain? - ANSWERS-The lowest piping of a gravity drainage system that
receives the discharge from soil, waste, and other drainage pipes inside the building that
extends a short distance from the building and conveys the drainage to the building sewer
What is the measurement from horizontal that separates horizontal and vertical drainage
stacks? - ANSWERS-45 degrees
Does an interior drainage stack that offsets 45 degrees or less from the vertical require a change
in size? - ANSWERS-No. Any more than a 45 degree offset requires sizing the offset as a house
drain.
What is a branch interval? - ANSWERS-A building story or a distance between two branch
connections greater than 8 feet apart.
Describe the procedure for sizing interior drainage stacks. - ANSWERS-1) First size the horizontal
branches connecting to the stack 2) Determine the minimum size that will accept each branch
at one branch interval 3) Total all fixture units connected to the stack, and determine the size.
The minimum size must be at least equal to the largest diameter required at the base. You may
reduce in size at upper branch intervals, but never by more than 1/2 the largest size.
What is the total recommended maximum permissible flow in a stack? - ANSWERS-7/24 of the
total cross sectional area of the stack.
Where should and shouldn’t you connect branch connections to stack offsets? - ANSWERS-
Not to the horizontal offset to the stack if at all possible, unless its at least 10 pipe diameters
downstream, and ideally 2 feet above the offset or 2 feet below to avoid pressure fluctuations.
Complete Solutions48
What is the design criterion for storm water sizing? - ANSWERS-The required rate of discharge
from any collection area, dependent on the size of the area, and the maximum rate of rainfall
per hour.
Why is condensation a concern for roof drainage and how can it be overcome? - ANSWERS-Low
temperature liquid flow in storm water piping will cause condensation to form on piping inside
the building. Insulation of pipes and roof drain bodies will keep the condensation from dripping
onto the ceiling or floor.
The connection to roof drains should always use what? - ANSWERS-An expansion joint, either
integral or separate. This prevents the pipe expansion and contraction (from severe outdoor
temperature swings and a fairly constant inside temperature) from raising the roof drain and
destroying the integrity of the water proofing at the roof.
If the storm piping is run separately from the sanitary piping, how many traps are required
before connection to the sanitary system or combined sewer? - ANSWERS-One.
What is different about storm water drainage system design? - ANSWERS-Design of a storm
drainage system is based on the piping flowing full under uniform flow conditions. Downspouts
(also called conductors or leaders) and horizontal piping can also flow full as maintaining
hydraulic pressures within any fixed limits in the system is not necessary as it is in a sanitary
drainage system.
Define Stormwater: - ANSWERS-Rainwater, surface runoff, ground water, subsurface water, or
similar clear liquid wastes, exclusive of sewage, condensate, and industrial waste
,What does the Manning Formula describe? - ANSWERS-The velocity of uniform flow in sloping
drains.
Front - ANSWERS-Back
What is the specific weight of water? - ANSWERS-62.4 lbs per cubic foot
What happens in a storm and sanitary system after it passes the water test? - ANSWERS-A
smoke pressure test is recommended with a smoke pressure of 1 in wc to prove the system gas
tight.
Is an air test acceptable for a storm and sanitary system? - ANSWERS-Yes, if a water test is not
possible, at a pressure of 5 psi, are tests are impractical and costly
What are the testing procedures for the storm and sanitary system? - ANSWERS-A water test
upon completion of the rough piping and prior to concealment of 10 ft wc minimum (except the
topmost 10 feet of pipe), not to exceed 100 ft wc. If system is higher than 100 feet, test plugs
must be installed to facilitate testing, rarely are more than 7 stories tested at one time. A
peppermint oil test may also be done with 2 oz of peppermint oil and 10 qt boiling water, and
searching for peppermint smell at leaks, however it is difficult to pinpoint the leak by this
method
The maximum length from the vent connection to any future drain outlet is required by code,
why, how long is the distance (listed in the book), and what’s the exception? - ANSWERS-To
prevent a dead end where slime, sludge and fungi can grow, 2 feet, unless the piping must be
extended to an accessible location for a cleanout
A sanitary tee may be used in the vertical but what may not be used in the vertical and why? -
ANSWERS-A double sanitary tee because the possibility of flow crossover and excessive
pressures when one branch is discharging and the other isn’t are possible
,What are the slopes of pipe inside the building that correspond to 2 fps velocity? - ANSWERS-
1/4 in per foot for 3 in and smaller 1/8 in per foot for larger pipe all elbows, taps, tees etc are
tapped at a pitch of 1/4” per foot
Where should cleanouts be provided? - ANSWERS-1) Inside or outside the building at the point
of exit (use a wye branch) 2) at every change in direction greater than 45 degrees 3) every 50
feet for piping 4” and less, and 100 ft for larger piping 4) underground piping larger than 10 in
should be provided with manholes at every change in direction and every 150 feet 5) at the
base of all stacks 6) as required by code
What size cleanouts are provided in piping? - ANSWERS-Piping up to 4 inches, the cleanout is
the same size as the pipe. Piping greater than 4 inches, 4 inch cleanouts are adequate.
What should be installed in the house drain if there is a danger of backflow of sewage into the
building? Whats the difference? - ANSWERS-A backwater valve or a combination BWV with
manually operated gate valve. The BWV does not interfere with the airflow throughout the
system, and the gate valve is recommended where there is a history of backflow as a positive
means of protection.
Branch connections to the house drain should be made where and why? - ANSWERS-At the
upper portion of the pipe (above the 1/2 - 2/3 full mark) because: 1) there is a lower chance of
stoppages in the branch 2) there is less flow interference at the point of connection 3) When
there is no flow in the branch, the full area of the pipe is available to relieve pneumatic pressure
fluctuations in the house drain
How many fixture units are equivalent to 1 gpm continuous or semicontinuous flow and what
are examples of these types of flow? - ANSWERS-2 FUs, sump pumps, ejectors, air conditioning
equipment, water cooled, equipment, etc
What minimum slopes are required for building drains and why? - ANSWERS-3 in pipe and
smaller: 1/4 in/ft 4-6 in pipe: 1/8 in/ft 8 in pipe and larger: 1/16 in/ft to maintain 2 fps scouring
action if low flow fixtures are present, 1/4 in/ft for all is a good idea
, House drains are designed to flow how full? - ANSWERS-1/2 full to 3/4 full max under uniform
flow conditions
What is a house (building) drain? - ANSWERS-The lowest piping of a gravity drainage system that
receives the discharge from soil, waste, and other drainage pipes inside the building that
extends a short distance from the building and conveys the drainage to the building sewer
What is the measurement from horizontal that separates horizontal and vertical drainage
stacks? - ANSWERS-45 degrees
Does an interior drainage stack that offsets 45 degrees or less from the vertical require a change
in size? - ANSWERS-No. Any more than a 45 degree offset requires sizing the offset as a house
drain.
What is a branch interval? - ANSWERS-A building story or a distance between two branch
connections greater than 8 feet apart.
Describe the procedure for sizing interior drainage stacks. - ANSWERS-1) First size the horizontal
branches connecting to the stack 2) Determine the minimum size that will accept each branch
at one branch interval 3) Total all fixture units connected to the stack, and determine the size.
The minimum size must be at least equal to the largest diameter required at the base. You may
reduce in size at upper branch intervals, but never by more than 1/2 the largest size.
What is the total recommended maximum permissible flow in a stack? - ANSWERS-7/24 of the
total cross sectional area of the stack.
Where should and shouldn’t you connect branch connections to stack offsets? - ANSWERS-
Not to the horizontal offset to the stack if at all possible, unless its at least 10 pipe diameters
downstream, and ideally 2 feet above the offset or 2 feet below to avoid pressure fluctuations.
