Review the section Preparing for work, then complete the following.

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1 CHAPTER 4: PLANNING THE LAYOUT FOR A RESIDENTIAL EXTERNAL SANITARY DRAINAGE SYSTEM 105 WORKSHEET 1 Student name: Enrolment year: Class code: Competency name/number: To be completed by teachers Satisfactory Not satisfactory Task Review the section Preparing for work, then complete the following. 1 Using AS/NZS , research and define the term main drain. 2 Using AS/NZS , research and define the term branch drain. 3 Research your local sewerage authority requirements, and answer the following: a What is the name of your local sewerage authority? b Does your local authority maintain records of property sewerage drains? c Does your local authority require as-constructed sewerage plans when property sewerage drains are altered/extended, and if so within how many days of completion? d What are the plumbing permit requirements of your local authority for example, number of days before commencement, types of work? Explain your answer.

2 106 BASIC PLUMBING SERVICES SKILLS: SANITARY AND DRAINAGE 4 a What minimum depth of cover is required for a PVC sanitary drain in a garden area? b What minimum depth of cover is required over a PVC sanitary drain in a domestic driveway where the thickness of driveway concrete is 75 mm? 5 When planning the layout and installation of a sanitary drain, why is it good practice to first locate the point of discharge? 6 Research the soffit level requirements of your local authority. What is the minimum required height of the overflow gully grate or lowest fixture above the soffit of the sewer main connection? 7 When working in wet conditions, trenches can fill with water. Explain how you would dewater a trench and dispose of stormwater. 8 Give one example where planning and sequencing of tasks is important when laying sanitary drains. 9 Research your local authority requirements for inspection of sanitary drains. a Are inspections required for sanitary drains? YES/NO b Are inspections required for sanitary drains under buildings? YES/NO c Is it a requirement that sanitary drains be tested before backfilling? YES/NO

3 CHAPTER 4: PLANNING THE LAYOUT FOR A RESIDENTIAL EXTERNAL SANITARY DRAINAGE SYSTEM 107 WORKSHEET 2 Student name: Enrolment year: Class code: Competency name/number: To be completed by teachers Satisfactory Not satisfactory Task Review the section Planning the system layout, then complete the following. 1 What are three factors that must be determined from site inspection? a b c 2 What is the minimum size of the main line of sanitary drain? 3 What is the minimum size of a branch drain? 4 What are the fixture abbreviations for the following? a Basin b Sink c Shower d Water closet pan 5 Research AS/NZS and define the term fixture unit. 6 What are two types of connection to the approved point of discharge? a b 7 Why are boundary traps specified for property drains?

4 108 BASIC PLUMBING SERVICES SKILLS: SANITARY AND DRAINAGE 8 Research your local authority requirements. Is it permitted to install a ground vent at the top of a boundary trap shaft? 9 What is the standard that you must comply with when planning the layout for sanitary drainage systems? 10 Explain where an inspection shaft must be located. 11 The following diagram shows a trench in sand adjacent to a concrete footing L (?) a What is the minimum distance for L? b If the distance L was 1 m, is the trench permitted in this location? Explain your answer. c How would you determine the depth of the concrete footing? 12 What is the total fixture unit rating for a basin, water closet (with a DN 100 discharge pipe) and sink? 13 What is the minimum gradient for a DN 65 branch drain having a rating of 21 fixture units?

5 CHAPTER 4: PLANNING THE LAYOUT FOR A RESIDENTIAL EXTERNAL SANITARY DRAINAGE SYSTEM What is the nominal minimum gradient for the following drains? 65 mm 80 mm 100 mm 15 Why are jump-ups used in sanitary drains? 16 Explain when and why anchor blocks are used in sanitary drains. 17 Provide four reasons for providing ventilation in sanitary drains. a b c d 18 Research AS/NZS and define air admittance valve. 19 Why must air admittance valves not be used for ventilation of the main sanitary drain?

6 110 BASIC PLUMBING SERVICES SKILLS: SANITARY AND DRAINAGE 20 Size the external sanitary drainage system shown below. Tr.(L) Vent WC Bath B WC S Inspection shaft 21 What is the maximum allowable length for an unventilated branch drain with discharge pipe, and why? 22 Research AS/NZS and define the term surcharge. 23 What is usually used to prevent surcharge and overflow of sewage into a building? 24 What is the minimum vertical distance that the overflow relief gully grate must be beneath the outlet of the lowest fixture? 25 What is the minimum height that an overflow relief gully grate must be above the following? a Natural surface level b Paved surface level graded away from the grate

7 CHAPTER 4: PLANNING THE LAYOUT FOR A RESIDENTIAL EXTERNAL SANITARY DRAINAGE SYSTEM Why do some authorities require that reflux valves be located at least 80 mm higher than the downstream drain connection? 27 What is the common name for a 45 junction fitting? 28 Each of the following two diagrams represents a two-storey building connected to a sanitary drainage system. On the diagrams, insert the following: either boundary trap or inspection shaft drainage vents minimum size of main drain and all branch drains overflow relief gully inspection openings. a Non-boundary trap area S Tr,(L) B DN 100 stack Shr Bath WC Scale 1:500 Sewer main b Boundary trap area S Tr,(L) WC B DN 100 stack Shr Bath Scale 1:500 Sewer main

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