Specifications

STANDARD SPECIFICATION - BUILDINGS
DPI REFERENCE TEXT - APRIL 2009
PAGE 42
Installation
Generally: Install pipework in straight lines and
uniform grades. Provide unions, anges and
isolating valves for the satisfactory removal of
piping and ttings for maintenance or replacement
of plant. Arrange and support pipework so that
it remains free from vibration whilst permitting
necessary movements such as thermal expansion
and contraction. Keep the number of joints to a
minimum.
Accessibility
Location: Locate ttings requiring maintenance or
servicing, including control valves, joints designed to
enable removal of pipes, and the like, in accessible
positions, with adequate clearance. Arrange the
pipework so that it does not interfere with the removal
or servicing of associated equipment or valves.
Description of irrigation system
Use a xed location type with automatically or
manually operated sprinklers, sprays, microsprays
and drippers.
Performance of irrigation system
Coverage (mm of water over area to be watered):
50 to 60mm per week during the establishment
period and then progressively hardening off to local
conditions.
Ensure that nal water usage is such that plant
health and vigour is maintained without wastage of
water.
Backow
Fit a backow prevention device to AS/NZS 3500.1
and as required to meet the approval of the PAWA.
Automatic controls
Use electric solenoid valves wired to an irrigation
controller.
Irrigation controller: Mount the controller in a
weatherproof lockable cabinet. Include the following
features:
• Variable timer for each station with a range from
1 minute to not less than 30 minutes.
• Manual cycle and individual station operation.
• Manual on-off operation of irrigation without loss
of program.
• 240 V input and 24 V output capable of operating
2 control valves simultaneously.
• 24 hour battery program backup.
Micro irrigation system
Polyethylene irrigation pipe: To AS 2698.1
Class IRRIG with barbed ttings of similar pressure
rating fastened with ratchet type clamps. Lay pipe
on nished ground surface under planting bed
mulch and anchor at minimum 1.5 m intervals with
U-shaped stakes. Connect micro-tube laterals with
proprietary push in or screw in ttings.
Microsprays: Mount microsprays on stakes 300 mm
above ground and connect to the pipework with
microtubes.
LANDSCAPE
Requirement: Form a spade cut edge to a minimum
depth of 150 mm below the adjacent surface levels.
Align adjacent spade cuts to achieve smooth curves
and/or straight lines as required. Remove all grass
or weeds from the spade cut and maintain the edge
free from grass and weed growth.
Concrete Edging
Location: To garden edges against lawns and areas
not planted.
Edging Strip: N20 in situ concrete 175 mm wide x 90
mm high. Place in position on a cleared compacted
base with a forming machine to the layout shown on
the drawings or as directed.
Finish with a proled steel trowel and tool in control
joints at a maximum 2.5 m centres.
Prole: Rounded or splayed top.
21.16 IRRIGATION
Standard: To AS/NZS 3500.1.
Cross references
Refer to the following section:
• Sitepreparation: for excavating trenches.
Inspection - Witness Point
Witness Point: Give sufcient notice so that
inspection may be made of work ready for testing.
Hydrostatic tests - Hold Point
Hold Point: Fill the pipework with water and test at
the required pressure and duration.
Contractors design plans - Hold Point
Hold Point: Submit drawings indicating design
proposals showing all pipework, sprinklers, tanks,
valves and control systems for approval.
Work-as-executed drawings
Submit drawings showing the “as installed” locations
of all pipework, ttings, sprinklers, control valves
and accessories. Show the depth of underground
pipework. Show location of all controllers and
automatic control wiring, indicate colours used for
individual valves.
Connection
Connect the cold water supply system to the supply
authority’s main through a stop valve and meter.
Carry out the excavation necessary to locate and
expose the connection point. On completion reinstate
surfaces and elements which have been disturbed
such as roads, pavements, kerbs, footpaths and
nature strips.
Excavation and installation
Requirement: Excavate to the lines, levels and
grades as required for irrigation trenches. Trench
depths and widths as required by AS/NZS 3500.1.
Obstructions: Cut back roots encountered in trenches
to not less than 600 mm clear of the pipework.
Remove such other obstructions including stumps,
boulders and the like which may, in the opinion of
the Superintendent, interfere with the pipework.
Specifications March 2009.indd 42 11/03/2009 11:47:13 AM