Specifications

STANDARD SPECIFICATION - BUILDINGS
DPI REFERENCE TEXT - APRIL 2009
PAGE 39
21. LANDSCAPE
21.1 GENERAL
Cross reference
Refer to the General requirements section for timber
durability.
21.2 MATERIALS AND COMPONENTS
Concrete
Standard: To AS 1379.
Topsoil
Standard: To AS 4419.
21.3 PREPARATION
Weed eradication
Eradicate weeds using a non-residual glyphosate
herbicide in any registered formulae, at the
recommended maximum rate.
Surplus spoil
Remove surplus spoil from site. Do not burn
vegetative material.
21.4 INSPECTION
Notice - Witness Point
Witness Point: Give sufcient notice so that
inspection may be made of the planting and garden
edging setout prior to excavation and advanced tree
and palm holes excavated.
21.5 SAMPLES
Requirement - Hold Point
Hold Point: Provide the following samples for
approval:
• 5 kg bag of topsoil and test documentation.
• 5 kg bag of mulch.
21.6 SUBSOIL
Ripping
General: If practable rip parallel to the nal contours.
Do not rip when the subsoil is wet or plastic. Do not
rip within the dripline of trees to be retained.
Ripping depths: Rip the subsoil to the following
typical depths:
• Compacted subsoil: 300 mm.
• Heavily compacted clay subsoil: 450 mm.
Cultivation
Cultivate to a minimum depth of 100 mm. Do not
disturb services or tree roots; if necessary, cultivate
these areas by hand. During cultivation, thoroughly
mix in materials required to be incorporated into the
subsoil. Remove stones exceeding 25 mm, clods
of earth exceeding 50 mm, and weeds, rubbish or
other deleterious material brought to the surface
during cultivation. Trim the surface to the required
design levels after cultivation.
Additives
General: Apply additives after ripping or cultivation
and incorporate into the upper 100 mm layer of the
subsoil.
Gypsum: Incorporate at the rate of 0.25 kg/m
2
.
21.7 TOPSOIL
General
Provide sand based topsoil which is free from
unwanted matter and complying with AS 4419. Add
6 kg/m
3
of “Terra Firma Organic Life” and thoroughly
combine.
Source
Obtain topsoil from an approved source and keep
records of soil delivery.
Placing topsoil
Spread the topsoil on the prepared subsoil and grade
evenly, making the necessary allowances so that
required nished levels and contours are achieved
after light compaction; and grassed areas may be
nished 20 mm below adjacent hard surfaces such
as kerbs, paths and mowing strips.
Consolidation
Compact lightly and uniformly in 150 mm
layers. Avoid differential subsidence and excess
compaction and produce a nished topsoil surface
which is nished to design levels; smooth and
free from stones or lumps of soil; graded to drain
freely, without ponding, to catchment points; graded
evenly into adjoining ground surfaces; and ready for
planting.
Topsoil depths
Spread topsoil to the following typical depths:
• Planting areas: 250 mm.
• Irrigated grassed areas generally: 150 mm.
• Grass areas: 100 mm.
21.8 TURFING
Turf
Obtain turf from a specialist grower of cultivated turf.
Provide turf of even thickness, free from weeds and
other foreign matter.
Supply
Deliver the turf within 24 hours of cutting, and lay it
within 36 hours of cutting. Prevent it from drying out
between cutting and laying.
Fertilising
Mix fertiliser thoroughly into the topsoil before
placing the turf.
Laying
Lay turf as follows:
• In “stretcher” pattern with the joints staggered
and close butted;
• Parallel with the long sides of level areas, and
with contours on slopes and;
LANDSCAPE
Specifications March 2009.indd 39 11/03/2009 11:47:13 AM