TOPIC 9: Storm Drainage System

Question 1

DOWNSPOUTS OR CONDUCTOR
PIPES, GUTTERS
Round, square (sized to ____)
or rectangular (shall have at least the same cross-sectional area as its equivalent round pipe, except that the ratio of its side dimensions shall not exceed ____) rainwater pipes may be used for downspouts.

Answer 1

enclose its equivalent round pipe
3 to 1

Question 2

DOWNSPOUTS OR CONDUCTOR
PIPES, GUTTERS
Rainwater piping shall not be used as _____. Downspout and gutter sizes are based upon the maximum depth of rainfall per hour falling upon a given roof area in square meters. An ave. ____ rainfall intensity is used around Metro Manila.

Answer 2

soil, waste and vent pipes; 102 mm/hr

Question 3

DOWNSPOUTS OR CONDUCTOR
PIPES, GUTTERS
Downspouts for high-rise buildings shall be of stronger pipe materials to resist the ____, they shall be installed within a pipe chase, and have no intermediate branch from the roof to the ground level.

Answer 3

high hydrostatic pressure

Question 4

ROOF DRAINS
Roof drains shall be equipped with _____ extending ____ above the surface of the roof surface. With a minimum
total net inlet area of ___ times the area of the outlet pipe to
which it is connected.

Answer 4

dome-type strainers; 102 mm; 1 – ½

Question 5

ROOF DRAINS
Roof deck strainers shall be approved ___, with a total net inlet area not less than ____ the area of the outlet pipe to which the drain is connected.

Answer 5

flat-surface type; 2 times

Question 6

ROOF DRAINS
Roof drains passing through building interiors shall be made
watertight by the use of ____ drain with integrally-cast water stop
ring around the outside of the body and placed at mid-depth of the
concrete roof slab and the installation of a clamped suitable
flashing material around the drain.

Answer 6

C.I.

Question 7

3 Major Systems of
Collecting Storm Water

Answer 7

Independent System
Combined System
Natural System

Question 8

• Brings collected water directly
  to the water reservoirs
• a.k.a. ‘the Separate System

Answer 8

The Independent System

Question 9

Combines storm water
with sanitary wastes

Answer 9

The Combined System

Question 10

• Without using any roof gutters or downspouts
• Also when rainwater is collected in cisterns

Answer 10

The Natural System

Question 11

Storm Drain Locations

Answer 11

Inside, Outside, Overhead

Question 12

Roofing Elements to
Collect Rainwater:

Answer 12

Gutter
Downspout
Strainer or Roof drain
Shoe
Catch Basin
Storm Line
Storm Sewers

Question 13

Usually located along the
entire perimeter of the roof

Answer 13

Gutter

Question 14

Located every 8 to 10 meters
& at every corner of the roof
(but, to avoid clogging of pipes,
it is best to locate them every
4 to 6 m)

Answer 14

Downspout

Question 15

Drain designed to receive water collecting on
the surface of a roof and to discharge it into a
downspout. Designed to prevent clogging.

Answer 15

Strainer or Roof drain

Question 16

At the bottom of the roof leader to direct rainwater
towards the nearest catch basin

Answer 16

Shoe

Question 17

Downspouts should terminate in a catch basin (can serve more
than one downspout)
Delivers water to the sewers in the street via gravity
Area-Drain-Catch-Basin: also collects surface water

Answer 17

Catch Basin

Question 18

Connects to each catch basin

Answer 18

Storm Line

Question 19

• Carries only rainwater collected from the storm
  drain or from the streets
• Terminates at natural drainage
  areas (i.e. lakes, rivers, and
  water reservoirs)

Answer 19

Storm Sewers

Question 20

Storm sewers
require manholes to serve as
clean-outs and to make sewers
accessible for inspection and
repair built at depths of about _____ meters; diameter ranging from
____

Answer 20

2 to 3; 0.6 to 1.2 meters