1. Plan the Layout for a Residential Sanitary Drainage System (CPCPDR3021A)
Resources Required :
AS/NZ 3500 : Part 0 : 2003
Plumbing and drainage
Glossary of terms
AS/NZ 3500 : Part 2 : 2003
Sanitary plumbing and drainage

2. Sanitary Drain :
Pipe lines located above or below ground level within the property boundary, including all fittings and equipment generally external to a building, to convey under gravity, sewage or trade waste.

3. Main Drain :
The main pipe not including branches. Normally located below ground within the private property to convey the discharge from all soil and waste fixtures to the authorities sewer.

4. Branch Drain :
The section of drain designed to receive the discharge of fixture discharge pipes, which has a lower fixture unit loading and may be smaller than the main drain at its connection point.

5. Vented Drains :
Drains that include either upstream ventilation or both upstream and downstream vents that provide through air movement to ventilate the drain.

6. Unvented Branch Drains :
Branch drains where there is no through air movement and air is provided by the drainage vent located on the ventilated drain.

7. Size and Grades of Drains : (Reference clause 3.3 & 3.4)
Main Drain :
Minimum size of a main drain shall not be less than DN 100 mm.
Branch Drain :
Minimum size of a branch drain shall not be less than DN 65 mm.

8. Size of Drains : (Reference clause 3.3.6 & 3.3.8)
Drains shall not be oversized for the sole purpose of acquiring a grade less than the minimum grade as stated in Table 3.2
Drains shall not diminish in size in the direction of flow.

9. Minimum Grades of Drains : (Reference clause 3.4.1 & table 3.2)
The normal minimum grade of vented and unvented drains as stated below.
Table 3.2 Minimum Grades of Drains
Nominal Size DN Minimum Grade, %
65 mm
80 and 100 mm
125 mm
150 mm
225 mm
300 mm

10. Maximum Fixture Loading for Vented Drains “PART ONLY” TABLE 3.1
Grade Nominal size of drain, DN % X X

11. Changes of Direction : ( Reference clause 4.3.3 )
Changes in direction or gradient in drains shall be made by the use of bends or junction fittings or at inspection chambers.

12. Unvented Branch Drains :
(Reference clause 3.10)
Maximum Length :
The total length of unvented branch drain shall not exceed 10 metres from the vented drain to the weir of the trap, including the length of the fixture discharge pipe.

13. Size of Unvented Branch Drains Table 3.6
Size of Pipe Maximum Fixture Unit Loading
65 mm fixture units
(excluding a water closet pan or slop hopper), or 10 F.U.’s from one F.W.G.
80 mm fixture units
(including not more than one water closet pan or slop hopper)
100 mm fixture units
(including not more than 2 W.C.’s / S.H.’s)

14. Location Ductile iron Other materials
Depth of Cover : Table 3.4
Minimum Depth of Cover for Buried Piping Cast iron,
Location Ductile iron Other materials
Where subject to
heavy vehicular mm mm.
traffic.
Where subject to light mm mm vehicular traffic
Elsewhere Nil mm.

15. Proximity to Other Services : (Reference clause 3.6 & fig.3.3)
The separation between any underground drain and any other service other than consumer gas piping, electrical communication service or water service shall be at least 100mm. or 300mm. from stormwater drain exceeding DN 100mm.

16. Proximity to other services (cont.)
The separation between any underground electrical supply cable or consumer gas pipe shall be 600 mm. when not protected.
When marking tape is provided complying with AS/NZ and is mechanically protected the separation can be 100 mm.

17. Inspection openings on drains : (Reference clause 4.7 & fig.4.4)
Inspection openings are required on sanitary drainage systems to allow access to the drain for inspection and maintenance purposes.

19. Location of Inspection openings :
(a) As close as practicable outside the building on each branch connecting one or more water closets or slop hoppers but not greater than 2.5 metres.
(b) At each end of straight section of main drain at intervals of not more than 30 metres.
(c) At the connection to the authority’s sewer point.
(d) On the downstream end where any drain passes under a building except where waste fixtures only are connected.

20. Location of Inspection openings (cont) :
(e) Where any new section of drain is connected to an existing drain.
(f ) Immediately at or upstream of the upper bend of a jump-up.
(g) At every change in the horizontal direction greater than 45 degrees.
(h) At every change in gradient greater than 45 degrees.

21. Venting of Drains : (Reference clause 3.9)
Provision of Drainage Vents :
Drain vents shall be provided at both ends of any drain that incorporates a boundary trap, and at the upstream end only on boundary trap omitted drainage installations.

22. Location of drainage vents : (Reference clause 3.9.1 & 3.9.2)
Upstream vent :
The drainage vent shall be connected at the upstream end of any main drain or branch drain within 10 metres of any fixture or drainage trap, or as a stack vent located at or near the upstream end of the drain.

23. Location of drainage vents : (Reference clause 3.9.1 & 3.9.2)
Downstream vent :
The downstream vent shall be connected as a low level vent (ground vent) or within 10 metres of the boundary trap riser provided no other fixture is connected between boundary trap riser and the vent connection.

24. Size of drainage vents : (Reference clause 3.9.3 & table 3.5)
Minimum size :
The upstream and downstream vents on any main drain shall not be less than DN 50 mm.

25. Drain Design :
Drains can be designed to connect fixtures using the following methods:
Directly to the drain.
Directly to a disconnector gully.
Connect through a floor waste gully.
Connect to a disconnector gully via an unvented branch drain.

26. Direct connections to drains(clause 3.10.3)
A total of 10 metres (max.) overall length of unvented branch drain, providing the length of discharge pipe does not exceed
(a) 2 metres for water closets with DN 80 mm. discharge pipes.
(b)1.5 metres for “S” trap basins and bidets.
(c) 2.5 metres for all other fixtures.
(d) 10 metres to the weir of a D.G.

27. Drain Design (cont.)
Connections of fixtures to Disconnector/FloorWaste Gullies :
Waste fixtures only are permitted to discharge to disconnector gullies or floor waste gullies.

28. TABLE 4.1 Connections of Fixtures to Disconnector Gullies
Fixture Maximum unvented length
of waste pipe (metres)
Basins or bidets with
DN 40 traps and waste pipes
All other waste fixtures and
and Fwg’s. with DN50 or
smaller waste pipes.
Fwg’s. and fixtures with DN
or larger waste pipes.

29. Overflow Relief Gullies : (Reference cl. 4. 6. 6, fig 4. 1 & tables 4
To provide protection from surcharge or a possible blockage at the sewer connection point at least one overflow relief gully shall be provided in the drain except as provided in clause

30. Installation of Overflow Relief Gullies ( Reference clause 4. 6. 6
Overflow Relief Gullies must be installed with a minimum height of 150 mm. below the top surface level of the lowest fixture connected to the drain and maintain a 75 mm. minimum clearance above natural ground surface level.

31. Testing of Sanitary Drainage Installations : ( Reference Section 13 )
Water Test :
Water tests shall be applied to every new below ground drain or to any section of existing drain that has been repaired or replaced.
(Due to the current drought conditions air testing would be the preferred method of test.)

32. Testing of Sanitary Drainage Installations : ( Reference Section 13 )
Water Test Procedure :
The head of water shall not exceed 3 m.
Test time is 10 mins. for vitrified clay and 5 mins for drains of any other material.
Make-up water not to exceed 1 litre per m. of DN100 mm.vit.clay drain.
No make-up water for drains other material

33. Testing of Sanitary Drainage Installations : ( Reference Section 13 )
Air Test :
Apply a pressure of 30 kpa.to the drain and hold for 3 mins. to allow air to stabilise.
Shut off air supply and note the time taken to drop from 25 kpa to 20 kpa.
Drain is passed if time taken is more than 90 seconds for pipes DN 225 mm or smaller or 180 seconds for DN 300 & 375.

34. Question 1 Explain what a drain is ?
Plan the layout for a residential sanitary drainage system : BCPDR3001A Worksheet and Answers
Question 1 Explain what a drain is ?
Pipe lines located above or below ground level within the property boundary, including all fittings and equipment generally external to a building, to convey by gravity sewage or trade waste.

35. Write in full the abbreviation below :
Question 2
Write in full the abbreviation below :
Inspection opening
ORG DG B WC FW
Overflow relief gully IO IS UV HC JU
Disconnector gully
Inspection shaft
Bath
Upstream vent
Water closet
Heavy cover
Floor waste gully
Jump up

36. Question 3
What is the name of the standard that needs to be adhered to when designing drainage systems?
Australian/New Zealand Standard (3500:2003)
Part 2 : Sanitary Plumbing and Drainage

37. Question 4
State the purpose of specifications.
Before commencement plans and specifications are obtained from the builder or architect to provide information required to complete all necessary plumbing work and relevant start work notices.

38. Question 5
State five (5) OH&S requirements that need to be addressed when doing design work.
1. Height and position of draft board.
2. Support and comfort of the chair.
3. The quality of available lighting.
4. The period of time working.
5. The standard of equipment used to perform the necessary tasks.

39. Question 6
What quality assurance practices does your workplace require?
The work carried out is accurate to the job specifications and according to all necessary standards and local regulations.

40. Question 7
What quality assurance practices are required in your educational setting?
The work tasks are completed according to the evidence guide and the assessment checklist.

41. Question 8
Explain in your own words why it is important to sequence your work.
To allow the job to run smoothly and efficiently with less mistakes saving time and material costs.

42. Question 9
Write a list of equipment you will need to complete the residential drainage system.
Pencils
Set squares
Scale ruler
T. Square
Eraser
Drawing Board
Calculator
Computer
Drawing paper
Printer

43. Question 10
Explain how you would prepare your work area.
Before commencement set up the work area with all the necessary equipment to complete the design.

44. Question 11
In your own words explain what can be gained from a site inspection.
Allows you to determine the position of the building structure, other services and how the job may affect other trades.

45. Question 12
What is the minimum size the main drain needs to be?
D.N. 100 m.m.

46. Question 13
Define the following :
Sewer:
A conduit for the carriage of sewage, which is vested in the local sewerage authority.

47. Question 13 (cont.)
Define the following :
Main drain:
The main drainage system not including branches. Normally located below ground within the private property to convey the discharge from all soil and waste fixtures to the authorities sewer.

48. Question 13 (cont.)
Define the following :
Branch drain:
The section of drain designed to receive the discharge of fixture discharge pipes,which has a lower fixture unit loading and may be smaller than the main drain connection point.

49. Question 14
For ease of reading a design what colours are used for :
Main drain: Green
Branch drain: Green
Vent drain: Red

50. The local sewerage authority.
Question 15
Who determines if a boundary trap is required?
The local sewerage authority.

51. Question 16
Why may a boundary trap be required?
To prevent the sewer gases from the authorities sewer entering the property service drain.

52. Question 17 (a)
What cover is required for PVC in an area that has light vehicular traffic?
450 m.m.

53. Question 17 (b)
From what table in the standard can this be obtained?
Table 3.4

54. Question 18
What is the combined fixture unit rating of a bath, kitchen sink, water closet and laundry trough?
16 Fixture Units

55. Question 19
Why has a bathroom with a bath, shower, water closet and basin a fixture unit rating of 6?
Bathroom groups of fixtures would not all be used at the same time, this is why the rating is only 6.

56. Question 20
When drains are to be laid in close proximity to footings the design needs to ensure the structure is not compromised.
(a) What documentation needs to be used to determine this?
AS/NZ 3500:2 Fig.3.4 Footing Details (Table from BCA Housing Provision)

57. (b) For the design below the cut is in sand, what distance is “L”
Question 20 (cont.)
(b) For the design below the cut is in sand, what distance is “L”
CUT SAND
(1:2)
H = 1.2
L = 1.2 Divided by 1.2
Answer Distance “L” = 1 metre
1200 “H”
L(?)

58. Question 21
What is the minimum grade a section of drain having 21 fixture units can be laid at ?
65 m.m. 2.5%
80 / 100 m.m. 1.65%

59. Question 22
State the minimum grade the following drains can be laid at :
DN 65 m.m %
DN 100 m.m %
DN 150 m.m %

60. (Alternative position of vent) Authorities connection point
Question 23
Size the drainage system below :
Legend
F.w.g. = floor waste gully
IO = inspection opening
IS = inspection shaft
S = sink
Shr. = shower
Tr. = trough
WC = water closet
Bth. = bath
Drainage Vent
(min. size DN 50 mm.)
65 mm x 90 bend
Tr.
100 x 65 mm L.I.T.
65 mm x 90 bend
(Alternative position of vent) WC
100 mm x 90 bend
Bath Basin
ORG WC
100 mm x 90 bend
100 mm
Vented drain
65 mm x 90 bend
100 x 65 mm L.I.T.
65 mm. U.V.B.D. S.
Authorities connection point

61. Question 24
What is the maximum distance a branch drain can run without venting and why.
The maximum distance shall not exceed 10 metres to prevent possible siphonage occurring to the drainage or fixture trap water seals.

62. Question 25
If other services are likely to be near a drain what precautions need to be taken when designing the layout.
Take into consideration the position of the drain design to prevent damage to other services.

63. Question 26
What does the term “surcharge” mean and why is it important for drainage design.
To prevent damage to the inside of the building due to the overflow of sewage from the sewer drain as a result of “overloading or blockages” occurring.

64. Question 27
Describe two methods for preventing surcharge.
(1) Installation of Overflow Relief Gully below the lowest fixture connection to the drain.
(2) Install a Reflux valve.

65. Question 28
What method for preventing surcharge is the most practical in most domestic situations.
Install an Overflow Relief Gully.

66. Authorities connection point
Question 29
On the following diagrams indicate the location of inspection openings and an overflow relief gully.
Legend
FWG = floor waste gully
IO = inspection opening
IS = inspection shaft
S = sink
SHR = shower
TR = trough
WC = water closet
BTH = bath
Denotes IO
Denotes ORG Tr
Vent WC
ORG
Bath, Basin WC S
Authorities connection point

67. Question 29 (cont.)

68. Question 30 (a)
When designing drainage systems with stacks an exclusion zone at the base of the stack is required, explain why.
Due to foaming occurring near or at the base of the stack, fixtures are prohibited to connect within the
exclusion zones.

69. Draw a diagram below of the exclusion zone.
Question 30 (b)
Draw a diagram below of the exclusion zone.
Stack two floor levels or less
Exclusion zone
(as shown)
600 mm
500 mm.(min.)
Flow

70. (1) To provide a balance of air pressure within the drainage system.
Question 31
State three (3) reasons why ventilation is required on a drain.
(1) To provide a balance of air pressure within the drainage system.
(2) To assist in the self cleansing of the property drain.
(3) To prevent the loss of water seals in drainage and fixture traps.

71. Question 32
On the following diagrams design the ventilation requirements and name the vents.
(a) Non boundary trap area
Drainage Vent
K / Sink
Laundry
(Alternative position of vent) WC
Bathroom
Sewer

72. Question 32 (cont.) (b) Non boundary trap area Drainage VentWC
Bath
Trough
Sink WC
Drainage Vent
Inspection Shaft

73. Question 32 (cont.) (c) Boundary trap area Drainage Vent Drainage Vent
Property
Boundary WC
FWG
Bath
Trough
Sewer
Window
Sink
Boundary trap
Drainage Vent
(location due to window)

74. Question 33
A studio is to be built onto a property with an existing drain, design the drainage system. DV IO WC
100 mm. Drain laid at 1.65%
All fixtures connect direct to drain unless stated otherwise
Bath
Existing
Building
Trough
Sink
DN 50 mm DV IO WC
100 x 90 bend
Extension
Sink
65 x 90 bend IO IO IO
Inspection Shaft (Light Cover)

75. PLAN “A” 100X65 L.I.T. 100 mm drain @ 1.65% grade. 100X90 bd.
All fixtures connect direct to drain unless stated otherwise.
Shower and basin in En-suite discharge to a 65 mm f.w.g. (80 mm riser)
Bath, shower and basin discharge to a mm f.w.g. (80 mm riser)
C.W.M. to laundry trough and trough discharges to a 65 mm f.w.g. (80 mm riser)
DN 50 mm drainage vent located on separate branch due to the location of the window.
100X90 bd.
65 mm f.w.g. (80 mm riser)
100x65 L.I.T.
65 mm f.w.g. (80 mm riser)
D.V.
100x90 bd.
65 mm f.w.g. (80 mm riser)
100x65 L.I.T.
100x45 junct. &100x45 bd.
O.R.G.
Inspection shaft
Light cover

76. PLAN “B”
100x90 bd.
DN 50 mm D.V.
100X90 bd.
65 mm f.w.g. (80 mm riser)
100x90 bd.
O.R.G.
100 mm 1.65% grade.
All fixtures connect direct to drain unless stated otherwise.
Bathroom group of fixtures discharge to mm f.w.g. (80 mm riser) located at shower.
C.W.M. discharges to trough and trough to 65 mm f.w.g. (80 mm riser)
I.S.L.C.

77. PLAN “C” 100X65 L.I.T. I.S.L.C. 100 mm drain @ 1.65% grade. 65X90 bd.
All fixtures connect direct to drain unless stated otherwise.
Bath, shower and basin discharge to mm f.w.g. (80 mm riser)
C.W.M. discharge to laundry trough and trough discharges to 65 mm f.w.g. (80 mm riser)
O.R.G.
100x65 L.I.T.
65 mm f.w.g.’s (80mm riser)
65x90 bd.
100X90 bd.
100x90 bd.
65X90 bd.
100X65 L.I.T.
D.V.
100x90 bd.

78. ASSESSMENT TASK DESCRIPTION :
PLAN A SANITARY DRAINAGE SYSTEM LAYOUT FOR A TWO STOREY RESIDENCE REQUIRING THE PICK UP FROM FIVE (5) POINTS.
ONE OF THESE SHOULD INCLUDE A STACK FROM A SECOND FLOOR, TO A LEGAL POINT OF DISCHARGE, OR ON-SITE DISPOSAL SYSTEM.
ENSURE CORRECT IDENTIFICATION OF DETAILS IN THE PROPOSED LAYOUT.

79. ASSESSMENT I.S.L.C. DN100 mm stack vent 100X90 bd.
65 mm f.w.g. (80 mm riser)
O.R.G.
100 mm 1.65% grade All fixtures connect direct to drain unless stated otherwise w.c, shower and basin connect to stack at first floor level Bathroom group of fixtures connect to 65 mm floor waste gully C.W.M. discharges to laundry trough and trough to 65 mm f.w.g.
65 mm f.w.g. (80 mm riser)
100x90 bd.
DN 50 mm vent
100x65 L.I.T.

80. UNDERPINING THEORY QUESTIONS
1. How is ventilation achieved in an unventilated branch drain?
2. State the maximum length of an unventilated branch drain.
Ventilation is provided by the drainage vent located on the vented drain.
10 Metres.

81. 3. State the safety precautions for drainage trenches.
4. State the formula for setting a grade.
Trench shoring is required when the depth of trench exceeds 1.5 metres.
Fall = Length (Drain)
Grade (Proposed grade %)

82. 5. What aids would you use to lay a drain straight.
6. State the requirements for testing a drain.
String lines and laser levelling device can be used to ensure the drain is laid straight.
Water test or Air test are carried out according to the A.S/N.Z Part 2: 2003 “Section 13”