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1
STANDARD DETAILS & SPECIFICATIONS
for
HIGHWAY TREE PLANTING
Formally Adopted by the Executive of
Newcastle City Council
on 17 May 2006
2
STANDARD DETAILS & SPECIFICATIONS
for
HIGHWAY TREE PLANTING
This document aims to provide a set of guidelines and details for tree planting within or
adjacent to the public highway and for the various situations and conditions that are likely
to be encountered. The document is divided into five sections:
1 Introduction, background and supporting documentation for the Specifications
2 The planting operation – a work sequence
3 Specifications
4 Recommended trees – lists of species suitable for Newcastle upon Tyne
5 Detail drawings
1.00 INTRODUCTION 1.1 THE CASE FOR HIGHWAY TREES
1.1.1 There is a compelling case for trees in the centre of our towns and cities, alongside
main highways, in suburban streets and on development sites. In 1993, the UK
Strategy for Sustainable Development stated ‘Trees in towns are an important
resource which enhances the quality of our urban environment’. (1)
The aesthetic argument is often the strongest but often the most difficult to prove.
Expressed most simply, it could be said that trees improve our quality of life.
More obvious benefits include:-
- noise reduction
- control of airborne pollutants
- improvements to energy efficiency
- benefits for wildlife.
1.1.2 The City of Newcastle upon Tyne has formally adopted a tree strategy: ‘Trees
Newcastle, A Tree Strategy for Newcastle upon Tyne’. (2) This document contains
policy and guidance on the care and maintenance of the City’s tree stock and for
increasing the number of trees throughout the City to improve amenity, biodiversity
and to make Newcastle a greener and more attractive city. There is also a five year
Action Plan to achieve these objectives. Objective 7 states that the City
3
will…….’develop a programme to plant more street trees….increase the number of
street trees…..increase the number of trees in the City centre’.
1.1.3 It is quite easy to demonstrate that trees have a powerful impact on people’s
perceptions of the visual quality of streets and urban spaces. Not only do people
feel better in a tree-lined environment (whether or not the individual recognises this)
but they are prepared to pay to live in one. Studies in the United States have
demonstrated property values of up to 20% higher in a tree-lined street than
identical properties in a street without trees.(3) (There is no indication of how this
relates directly to the UK housing market).
Conversely, deformation of pavings, problems caused by fallen leaves and
branches, damage to adjacent services and adjacent buildings, and safety issues
have all been cited at one time or another as a reason not to plant trees. With
correct detailing of the planting area, careful choice of species and good
management most of the problems can be overcome, hence the reason for this
document.
1.1.4 Large, mature trees are the most valuable. Not only do they provide a much
needed sense of scale for people in the built environment but a mature Beech for
example can produce enough oxygen for ten people every year and fix over 2 kg of
carbon dioxide an hour. (4)
1.1.5 The survival of newly planted trees cannot be left to chance. Estimates for the
survival of new trees in urban areas start as low as 50%, with only 10% of dead
trees caused by vandalism. (5)
This need not be the case. Trees are highly adaptable to hostile environments and
with the correct specifications, choice of species and variety and attention to detail
at all stages of the project, there is no reason why survival and subsequent growth
should not be comparable to a non-urban situation. (Research indicates that mean
shoot extension of urban trees is only 58% of that in similar trees in a nursery or
arboretum environment). (6)
1.2 SPECIFICATION GUIDELINES AND SUPPORTING INFORMATION
1.2.1 The following sections propose methods for successful tree planting in situations
that are commonly encountered in Newcastle’s highway areas and provides
background information to the specifications. They include both paved and unpaved
sites and cover a range of tree sizes.
4
Where specific guidelines are given then reference should be made to the relevant
specification and drawn detail as indicated. .
The guidelines are set out under the following headings –
1.3 The Site Page 4
1.4 Planting Pits Page 5
1.5 Soil Page 7
1.6 Root Barriers Page 8
1.7 Drainage Page 9
1.8 Tree Support Page 9
1.9 Irrigation & Aeration Page 11
1.10 Tree Selection Page 12
1.11 Tree Guards Page 15
1.12 Tree Grilles & Pit Surfaces Page 15
1.13 The Planting Procedure Page 16
1.14 Establishment & Maintenance (years 1 – 5 inclusive) Page 17
1.3 THE SITE CONSTRAINTS 1.3.1 When an area is identified for tree planting there are a number of check procedures
that must be undertaken before a detailed design can be agreed -
Underground services - contact all Public Utility Companies to establish the
exact location of pipes, cables, etc.. Tree planting shall not take place directly
over live services unless they are in excess of 3m deep, or in the case of mains
water and drains, 5m deep.
Aerial services – trees must not be planted where, as they increase in size, they
may foul overhead cables, block windows or interfere with street lighting or
CCTV cameras.
Carry out a visual survey for constraints such as nearby street lighting,
overhead lines, road signs, and nearby junctions. The presence of any of these
may not prevent tree planting but it is advisable to contact City Engineering
Services, City of Newcastle upon Tyne, for advice. They will also be able to
advise on sight lines at the approach to any junctions or turnings.
Existing trees will affect the growth of the new trees due to shading and
competition and will affect the proposed planting location. New trees will not
thrive or grow evenly under the canopy of existing trees.
5
1. 3.2 Risk management – tree planting in highway situations, as in any other location,
has a number of attached risks that must be taken into account during the planning
and implementation of the scheme.
Long term risks from established trees include –
damage to persons or property from falling trees or debris from trees such as
branches, leaves and fruit.
damage caused by growing roots to surrounding pavings creating a hazard for
pedestrians and vehicles.
damage caused by roots to nearby property including building foundations,
drainage and other service lines.
obstructing sightlines, street lighting and road signs for drivers of vehicles
therefore creating a potential hazard to road users.
Risks to be considered during the planting operations –
access to verges etc. from active highway, possibly with traffic management
implications
excavation of tree pits and manoeuvring of soil, trees, paving materials adjacent
to active highway and pedestrian areas.
dangers to site operatives from vehicles on the adjacent highways.
1.4 THE PLANTING PIT
1.4.1 Existing Ground -
excavate one planting pit to act as a trial pit that will enable the following to be
established:
- quality of topsoil
- possible drainage problems
- the presence of underground services
1.4.2 Quality of topsoil – as defined in BS 3882:1994. It is possible to assess the quality
of soil by using a simple ‘finger and thumb’ test as outlined in the BS but essentially
a light, sandy and ‘open’ texture is required. Where the excavated topsoil from the
planting pit, and the surrounding soil, is of a suitable quality then it is of little benefit
to add any other medium during the planting operation with the exception of a slow
release fertiliser (such as Bonemeal or Scotts ‘Enmag’ ), applied at the time of
planting and at manufacturer’s recommended rates.
6
If the soil has a poor texture then it is possible to improve this with conditioners
such as peat-free compost made from recycled organic materials as available from
Parks and Countryside Training (PACT) within the area of the planting pit and
applied at an approximate quantity of 3 parts soil to one part compost. It is not
possible to make long term improvements to, say, pH or nutrient content, to such an
extent as to benefit the tree for more than its initial establishment period.
It is also important to recognise that digging a pit in clay soils and backfilling with a
lighter, free draining planting medium, is likely to result in the creation of a sump
into which water from the surrounding ground will flow. In these circumstances, a
drainage layer at the base of the planting pit should be provided or connection to an
established drainage system via pipework. (see section 1.7)
1.4.3 New Ground -
In new ground, or in areas of major excavation, it is possible to create conditions
that will give new trees the best possible start and minimise future disruption to the
surrounding area. This will include:
- adequate soil volumes
- good quality topsoil
- protection to surrounding pavings and adjacent services
- drainage provision if necessary
In urban areas, where little or no existing soil is within reach of growing roots, the
size of the planting pit and the quality of soil are the two most important factors that
will have a bearing on the future growth of the trees.
1.4.4 Pit Size - Soil Volumes
The volume of soil required to support a mature tree depends on type and ultimate
size of the tree, water availability and ground water storage, particularly during drier
seasons. While formula are available to calculate the volume of soil required,
20 cu m appears to be required to maintain reasonable growth in a paved situation.
(7)
When planting into existing areas this volume may be difficult to achieve but it must
be recognised that trees planted in a lower volume of soil may not reach their
ultimate mature size and maintain good leaf growth/ shoot extension, unless their
roots can extend beyond the pit into adjacent soil areas, e.g., grass verges,
gardens, etc. (8)
7
Where possible a minimum soil volume of 5 cu m should be provided. The shape of
the soil area need not be regular and can be altered to suite site conditions.
Volume cannot be achieved by providing extra depth. The maximum useful depth of
topsoil for tree planting is 900mm.
It is acceptable for more than one tree to utilise the same soil. For example, a tree
pit 900 mm deep x 3 m wide x 8 m long containing 21 cu. m. of soil could support
two trees
planted at 6 m centres. A similar pit 16 m long containing 43 cu. m. would support
three trees, and so on. (see Diagram No. 6)
1.5 SOIL 1.5.1 Imported topsoil shall be of good quality, with a light texture, and conform to
BS 3882 ‘General Purpose Category’. Unless the topsoil is from a reliable source
that previously supported good plant growth the following tests are required:
- pH - the soil pH should be between 5.5 – 7.8
- organic matter - which should be greater than 5%
- Nitrogen (N) - which should be greater 0.2%
- Phosphorous - which should be greater than 45 mg/kg
- Potassium - which should be greater than 240 mg/kg
- Magnesium - which should be greater than 80 mg/kg
More involved tests for phytotoxic elements (e.g. copper, nickel, zinc) and zootoxic
elements (e.g. arsenic, lead, mercury) need only be undertaken if there is any doubt
regarding the origin of the topsoil.
The tests must be undertaken by a recognised testing laboratory and presented to
the client prior to importing topsoil to the site.
1.5.2 The planting pit shall be backfilled only when the weather is dry and the soil in a
relatively dry condition. The pits should be backfilled in layers not exceeding
300 mm and lightly ‘settled’ rather than compacted between each layer. As long as
the soil is not wet or heavy this is best achieved by light treading.
1.5.3 Areas of new ground - there are two alternatives for a planting medium - topsoil or
a ‘manufactured’ soil (often referred to as ‘Amsterdam’ or ‘load bearing tree soil’).
The main reason behind the development of 'load bearing tree soil’ was the search
for a planting medium that could be compacted sufficiently to withstand vehicles on
8
a surface paving material while maintaining optimum conditions for root growth.
Compaction of typical topsoil sufficient to support vehicular paving will result in the
removal of the voids that water and oxygen would have filled.
Correctly installed, the ‘tree soil’ is the ideal medium in this situation; it will not
deflect more than a few mm even when vehicles regularly use the surface. While
‘tree soil’ is easy to specify and clean to use, it is expensive and, more importantly,
has a limited nutrient content. In the long term, supplementary feeding is likely to be
necessary to maintain tree growth. Where vehicle overrun is likely to be only
occasional then topsoil, with a reinforced paving surface, is to be preferred.
1.5.4 If the organic content is low or the structure of the soil can be demonstrated to be
poor (see 1.5.1 above) then a peat-free planting compost should be added at the
suppliers recommended rates. Alternatively, compost from a reliable source (see
note re PACT above) can be added at a rate of 1:3, by volume, ameliorant to
topsoil. In all cases the mixing must be carried out before adding the soil to the
excavated tree pit in order to obtain a homogenous mix. It is important to realise
that the gradual decomposition of organic material in the soil, resulting in a series of
small but linked voids, is one cause of settlement in surface paving adjacent to tree
pits. For this reason, ‘load bearing’ tree soils are exceptionally low in organic
matter, not exceeding 5% by volume. (For compaction specification see 2.02)
1.6 ROOT BARRIERS 1.6.1 Where there is concern that adjacent services, such as gas and water pipes and
electricity cables, might be affected by growing root systems then an impenetrable
barrier should be installed which will prevent damage by future root growth.
1.6.2 A properly installed root barrier will, in effect, form a container and should be fitted
to the edges of the pit. Where there is danger of damage to services on just one
side, or any other reason why roots should be prevented from growing in one
direction such as building foundations, a strip barrier is preferable such as
Greenleaf ‘Reroot 1000’. The barrier must be installed from surface level to a
minimum of 1.0 m below surface level with joints overlapped by 300 mm. (see
Appendix 1)
9
1.6.3 In a new build situation, within 8m of building foundations or adjacent to service
runs that are deeper than 1m the barrier must extend to a depth of 2m – Greenleaf
‘Reroot 2000’ or similar. (see Appendix 1)
1.6.4 Where excavation is limited to the area of the planting pit a pre-formed barrier (e.g.
Greenleaf ‘Root Directors’) shall be installed to manufacturers instructions. The
barrier must be manufactured in such a way as to discourage the tree roots to spiral
around the inside but encourage them to grow in a downward direction.
In paving, the backfill surrounding the ‘root – director’ must be compacted
sufficiently to support the paved surface material and discourage roots that emerge
from the base of the ‘director’ from reaching back up to the surface layers. (see
Diagram No. 4).
1.7 DRAINAGE 1.7.1 It is a prime requirement of any tree planting situation that planting pits do not hold
water and become waterlogged. In new construction the minimum requirement is a
layer of stone consisting of 200 mm deep of clean aggregate 50mm nominal size in
the base of the pit topped with a geotextile blanket, e.g Terram, to reduce
contamination of the drainage layer by fines. This will allow surplus water to drain
freely from the rooting zone.
The optimum solution is to connect this drainage layer of individual tree pits via
pipes to an existing surface water drainage system. In adopted highway this must
be done in full consultation with City Engineers (telephone number 0191 232 8520).
1.8 TREE SUPPORT – STAKING AND GUYING 1.8.1 The purpose of staking and guying is to anchor the tree and stabilise the rootball
until new roots are established into the surrounding soil, it should not be seen as a
method of protecting from vandalism or physical damage. For this reason, support
is required until the roots, damaged during the lifting process, have made sufficient
new growth. In reasonable growing conditions this should be achieved within three
seasons after planting.
Above ground supports must be removed as soon as the tree is growing strongly,
an indication that the roots are re-established, thus allowing the main stem to bend
and sway in the wind which leads to increased thickening of the trunk. Trees where
the removal of the stakes has been delayed may exhibit a reduced girth, and
10
therefore a weakened stem, in relation to the crown growth that can lead to the
stem snapping in a strong wind.
1.8.2 There are two main methods of supporting a newly planted tree, either above
ground by timber stakes, or underground with taut cables. Additionally there may be
cause to use a hybrid of the above systems which uses tightly anchored cable to
support the trees above ground in the form of guys however this is to be
discouraged in public areas where the cables may present a health and safety
hazard. Above ground staking is unlikely to be successful with trees having a girth
greater than 30cm and a below ground system should be used.
1.8.3 Staking usually consists of one, two or three untreated softwood timber stakes, 75-
100 mm diameter, driven at least 300 mm into the base of the pit.
Research indicates that the height at which the stake is attached to the tree has a
direct bearing on the subsequent growth and establishment of the tree. A tree will
establish anchor roots and increase stem girth more quickly if it is allowed to move
with the wind (while remaining firmly fixed at ground level).
This is best achieved by either using low stakes which are attached to the tree at
approximately 600 mm above ground level or by a higher triple stake system which
allows the tree a degree of movement between three ties.
A further advantage of low stakes is that snapping a young tree is much more
difficult when the lever point is low as opposed to a rigid point 1.5 m or so above
ground.
1.8.4 The tree should be fixed to the stake using proprietary rubber ties or a material such
as canvas hosing. Whatever product is used it is essential that it is firmly fixed and
that a spacing device prevents the tree chafing against the stake. (see Diagram
No.s 1E,2A,2B, 2C & 3A)
1.8.5 Support below ground is achieved by the use of cables, tensioned between
anchoring devices located at the base of the pit, across the rootball. It can only be
reliably used where the tree has a solid, firm rootball, which is supported by hessian
wrapping within an ungalvanised wire mesh ‘basket’. If underground staking is
proposed then it must be specified that the supplying nursery lifts and prepares the
11
rootball using this method. The wire mesh basket should extend across the top of
the rootball thus providing protection to the roots from the taut cables.
It must be noted that, in nursery conditions, some varieties of trees never establish
a root structure that is dense enough to provide a solid rootball, e.g., some Sorbus
aria varieties. These trees cannot be supported by this method and double staking
will be required. Again, the supplying nursery will provide advice.
1.8.6 Specialist proprietary ground anchor systems, such as Platipus, are available for
anchoring the cables and are useful where the ground below the base of the pit
makes driving a timber stake difficult.
1.8.7 In reasonable ground conditions, a triangular system of timber stakes 75 – 100 mm
diam., connected to each other using 5 mm diam. multi -strand galvanised wire
fixed with staples, and driven adjacent to the rootball so that the wires are drawn
taught across the top of the rootball. The mesh basket must not be cut or loosened,
it will rot away naturally without any danger of restricting root growth. The mesh
should also protect roots from the wire but if there is likelihood of damage the wire
can be sheathed in a length of plastic hose.
On no account must stakes be driven through a rootball as root damage is
inevitable. Timber stakes increase in size when in contact with ground water and,
as a result, hold tighter than metal stakes. For this reason timber stakes are to be
strongly preferred. (see Diagram No.’s 1A,1B & 1D)
1.8.8 Alternative methods of anchoring the trees such as timber or concrete deadmen in
the base of the pits may be considered where it is not possible to drive stakes.
These must be placed at the time of pit excavation and fitted with all necessary wire
cables prior to back filling the pit and planting the tree. Tensioning of the wire is by
turnbuckle or ratchet systems. (see Diagram No. 1C)
1.9 IRRIGATION & AERATION 1.9.1 Research has shown that a proactive rather than a reactive approach to tree
irrigation during the first two or three seasons will have huge benefits to
establishment and longer-term growth. Applying water to newly planted trees that
are starting to show signs of drought stress may well keep them alive but will not
12
stop stem die-back. This will result in poor establishment and possible long term
structural problems.
1.9.2 Surface irrigation is appropriate at planting time, particularly if this is towards the
end of the planting season when bud-burst may only be few weeks away, and with
bareroot stock. A thorough soaking of the ground around the base of the tree will
ensure that soil is washed into voids around the fine roots of a bareroot tree or that
a rootball becomes thoroughly soaked.
A rootball composed of a different soil type to that in which it is planted may shrink
leading to voids between it and the sides of the pit which new roots are unable to
cross.
1.9.3 Later in the season, particularly during hot summer months, surface watering is
rarely efficient as the water is unlikely to penetrate the deeper root zone. It may
also result in roots remaining near the surface, which is to be avoided as much as
possible in a paved situation.
For future irrigation, the best method of ensuring correct water placement is by use
of a pipe leading from the surface to a point approximately 2/3 of the depth of the
rootball. From this point the pipe should encircle the rootball or, in the case of a
bare root tree be immediately adjacent the outer roots, and the water dispersed
through perforations in the pipe.
Proprietary systems are available e.g Greenleaf ‘Root Rain system’. It is important
to provide a removable cap to the open, above ground, end of the pipe to prevent
blocking by debris. Water fed directly into the system via a hosepipe will be placed
at exactly the correct location while waste through spillage and evaporation will be
minimised.
1.10 TREE SELECTION 1.10.1 The following issues must consideration when making a choice of trees for planting
adjacent to the public highway:
ultimate mature height -
- small – to approximately 10m
- medium – to approximately 15m
- large – greater than 15m
13
- ultimate shape and spread – in general, when planting adjacent to highways,
particularly where high sided vehicles regularly pass, it is preferable to select a
variety with relatively upright growth that will not require regular pruning or be
damaged by the passage of vehicles. Away from the immediate kerb line a
broader crown could be considered.
site conditions – as long as the soil is free draining and near-neutral pH then
most commonly specified street trees will grow well. Exposure, particularly to
strong and cold winds, may be a problem for some trees particularly those with
large leaves, a weak branch structure or brittle wood.
species specific or varietal features –which may be good or bad. For example, a
tree that has good spring flowers, autumn berries or autumn colour may be
positive features, while fruit that causes problems on footpaths or is attractive to
children is likely to be considered negative qualities by some and should be
avoided in the public realm.
1.10.2 A list of trees suitable for planting adjacent to the highway in Newcastle upon Tyne,
and those that are not, is included in Section 4.
1.10.3 Size of Planting – for street planting trees will be selected from one of the following
girth sizes:
Standard
8-10 cm where damage is unlikely, or the tree can be
adequately protected, and initial impact is not a
priority
Selected
Standard
10-12 cm the above comments apply
Heavy
Standard
12-14 cm likely to require protection in a public situation but
will provide a greater initial impact
Extra Heavy
Standard
14 -16 cm more resistant to casual damage and generally the
preferred minimum size in a public location
14
Semi Mature 16-35 cm trees of this size will provide good resistance to
casual damage and provide excellent initial impact.
However they require specialist handling and greater
attention during the establishment period.
Mature 35 cm + the above comments apply.
1.10.4 It is generally accepted that the smaller a tree is at planting the quicker it will
establish and start into new growth. There is evidence to suggest that a small tree,
say 8-10 cm girth, growing quickly, will catch up with and initially overtake in size a
tree planted at, say 16-18cm. Smaller trees are also cheaper to purchase and to
plant.
Drawbacks to planting the smaller sizes include lack of immediate impact and ease
of damage through vandalism. (A tree with a girth of 17cm is 35 times stronger
than one with a 7cm girth, explained by the formula 0.0491 x d4 where d =
diameter).
Some genera are considered less tolerant of transplanting at larger sizes eg.
Beech, Birch and Oak. However, modern nursery practice and a greater
understanding of root preparation has improved the situation. If the tree is
purchased from a reliable source, size and type should not be a major factor in its
survival after planting.
For urban situations it is recommended that newly planted trees have a minimum
girth of 14cm. Where there is a high risk of damage then the minimum
recommended girth is 18cm.
1.10.5 Root Type - bareroot v. rootballed v. containerised – these are the three choices of
root preparation available and on which a decision must be made at the time of
specifying the trees from the supplying nursery.
Each method has its advantages and disadvantages.
Bareroot trees are, usually, cheaper than other root types, especially as the trees
tend to be sold while younger and smaller. It is also generally accepted that,
providing correct nursery and subsequent handling practices are followed, a bare
root tree will establish quicker than any other type. This is largely because when a
tree is lifted for rootballing or containerisation (as opposed to a tree that has been
15
grown in a container throughout its life) many of the fine roots are left behind and
have to be regenerated before the tree can take up moisture and nutrients.
Bareroot trees retain much of the essential fine root system if lifted, handled and
protected correctly in the nursery, during transportation and on site.
Bareroot supply is the preferred option for trees of 18cm girth and below. Above
this, the advantages do not apply as rootballs are larger and to achieve a bare root
without much fine root loss would make the size of the root impractical for handling
and storage purposes. The damage caused to the roots is much less with the larger
rootball, the trees are well protected against drying out so handling and storage is
not so critical. Above 18cm girth a rootballed tree is the preferred option.
Both containerised and rootballed trees can be used to extend the planting season,
in theory a container tree can be planted at any time of the year but irrigation is
essential (see 13.01).
1.11 TREE GUARDS 1.11.1 The aim of tree guards is to reduce the likelihood of damage, either deliberate or
accidental.
The main requisite of any guard is that it is fixed rigidly vertical, usually by fixing
either to or under a grille, and of sufficient height to reduce the likelihood of the tree
being snapped at the top of the stake or at arms height. The top edge should be of
a design that reduces the likelihood of damage to the tree by chafing. Tree guards
used within the City of Newcastle upon Tyne will be selected from the Greenleaf
range or similar to approval (see appendix 1)
Where damage from manoeuvring vehicles is likely, such as car parks or on a verge
where vehicles habitually park, a raised kerb detail surrounding the planting pit is to
be used. (see Diagram No.5)
1.12 TREE GRILLES & PIT SURFACING 1.12.1 In a highway or street situation where trees are not planted in a grass verge or
shrub bed, there are three options for the surface of the planting pit - bare soil,
decorative grille or a porous aggregate.
1.12.2 Bare soil has inherent problems. It needs regular maintenance to keep it weed-
free, the surface is likely to become compacted and sink below the surrounding
paving level and, in suburban areas particularly, is likely to become a dog’s latrine.
16
1.12.3 Decorative grilles, either metal or plastic polymer, give protection to the soil around
the base of the tree. Polymer types have the advantage of not rusting or changing
colour and they have no scrap value, but limitations of the material and the
manufacturing process result in a restricted range of patterns and designs. There
are virtually no limitations to the patterns of metal grilles.
Where site conditions allow, it is generally better to use the largest size grille
possible, thus maximising the amount of surface water reaching the planting pit.
This is only of benefit during the early years of the tree. Once the roots extend
beyond the area of the pit the area of open grille is of limited benefit to the tree and
its function is mostly decorative.
Unless future removal or an exchange of grilles can be guaranteed, it is also wise to
avoid a small central aperture. While a larger opening, a minimum diameter of 400
mm is recommended, may appear too large at the time of planting it will allow room
for trunk growth. Some grilles are supplied with inner rings that may be removed to
accommodate the increase in stem girth. It is essential that grilles, of any material,
be supported by a frame which, in turn, is supported on at least two sides. Laying
the grille, with or without a frame, directly onto the soil of the planting pit will,
eventually, result in an uneven surface as the soil sinks in the pit.
Where a guard is to be used it is important that the design is compatible with the
grille and integral fixings are provided.
1.12.4 For trees in the adopted highway the pit surface is to be finished with a porous resin
bound aggregate with no grille. Where regular vehicular overrun is likely the
addition of a honeycomb cell matrix that provides additional rigidity and support is
required.
This system requires careful handling by the contractor in order to ensure the
correct mixing of the resin binder and aggregate. Manufacturers instructions must
be strictly adhered to. (see Appendix 1 and Diagram No.’s 1B,2D, 4,5 & 6)
1.12.5 Where trees are to be planted into a bitumen macadam surface then the area
surrounding the pit surface and overlying the soil into which the roots will grow
should be constructed using an open-textured permeable bitmac. This will be a
60mm thick wearing course of 10mm aggregate laid over no-fines aggregate or a
porous no-fines concrete.
17
1.13 THE PLANTING PROCEEDURE 1.13.1 Planting time - it is generally accepted that the planting season for trees runs from
mid November to mid March, when deciduous trees remain dormant. Rootballing,
cold storage and containerisation can, to some extent, extend this period. However
any tree planted after early March will be on the verge of coming into leaf. Additional
stress, through root damage or drought, at this critical period will lead to poor leaf
and root development from which the tree may never recover. Death, though not
inevitable, may occur some years later and be beyond the contract defects period.
Any planting beyond the March deadline must only be carried out if a
comprehensive and regular irrigation programme can be guaranteed. As a general
rule tree planting must only take place between mid November – first week of
March.
1.13.2 Planting depth - The depth must be measured against the tree, either by trial and
error for a tree that is easily lifted or by measuring from the base of the rootball to
the ‘collar’ at the base of the trunk where it starts to thicken out above the roots. A
straight edge laid horizontally over the pit, edge to edge, will provide a gauge by
which to judge the correct depth. Traditionally trees have been planted at a depth
indicated by the ‘nursery mark’, a dark area of stem extending above the root zone.
Recent research shows that this is not a reliable indicator of the correct planting
depth and may be the cause of many tree deaths. (Bib) This mark must not be used
as a method of establishing the correct planting depth.
1.14 AFTERCARE & MAINTENANCE 1.14.1 Maintenance of newly planted trees for at least 3 years, after planting is essential to
their long term survival and growth. Larger trees in particular, those above 25 cm
girth, can take several years to finally die, living off stored resources rather than
newly acquired ones. A guarantee period of at least 3 years, 5 years for trees of 35
cm girth and above, must be imposed on all new tree planting.
1.14.2 Incorrect handling at any stage of the works, failure to prepare the planting pit
correctly, poor planting techniques and lack of moisture at first bud-burst can lead
to poor establishment during the first 12 months of the tree in its new position. A
tree may be in leaf at the end of its first growing season but unless it has made
18
sufficient growth to sustain it well into the next season it is likely to be on a
downward spiral from which there is no return. A tree showing lack of vigour at the
end of its first growing season should be treated the same as a dead tree and
scheduled for replacement.
1.14.3 Operations to be carried out during the maintenance period must include:
- Watering – a minimum of 90 litres / tree shall be applied at fortnightly
intervals between the period 1st May to 30th September. If April is dry, newly
planted trees should be watered during this month at the same frequency. If
particularly wet weather occurs, supplementary watering may be
unnecessary. The use of larger quantities of water at greater time intervals is
not an adequate alternative and is not acceptable.
- Pruning – at the time of planting any damaged branches must be cut back to
a main junction or stem. Also beneficial to the tree is the reduction of crown
growth by removing weaker side branches. At the end of the first season of
growth, any branches showing signs of dieback must be cut back to live
wood. Pruning must take place during the dormant period except for Prunus
species when mid-summer pruning is recommended to reduce the likelihood
of disease. Pruning cuts shall not be painted with any type of wound sealing
paint.
- Support – Check trees for stability and if necessary re-tie or expose
underground supports to tighten the wires.
- Tree pits shall be kept clear of weeds and trees planted in grass must have a
bare circle of soil at least 1m in diameter maintained around the trunk. This
reduces competition from grass and the likelihood of damage from mowing
machines.
1.14.4 Long term management and maintenance of the trees should not be forgotten after
the defects period is complete. Monitoring of growth, and for damage by storm, by
vehicles or by vandalism should be carried out on a regular basis and any
necessary remedial action taken. Timber stakes must be removed three years after
planting and when the tree is showing signs of strong growth. Maintenance of an
area of bare soil around the base of the tree helps to reduce damage by mowers
and other grass maintenance equipment.
19
2.00 THE PLANTING OPERATION – A WORK SEQUENCE
2.01 Planting in existing ground –
Prior to work commencing on site:
obtain service and utility information and complete a visual inspection for
possible constraints to the proposed scheme (para. 1.3.1)
carry out a risk management assessment for site operatives and users during
the entire planting and maintenance operations of the trees (para. 1.3.2)
consult existing residents / occupiers of adjacent properties and inform them of
the draft proposals and programme
make any necessary amendments to the proposals in response to comments
following the public consultation
Site works:
excavate one tree pit to investigate soil quality and drainage and assess
surrounding ground conditions (para 1.4.1)
excavate that number of tree pits which can be planted during the same day.
Any open pits must not be left uncovered when operatives leave the site.
Provision must be made to cover open pits with a board and warning tape
erected around the area.
where necessary carry out amelioration of the excavated topsoil, mixing on a
board outside the pit to obtain a homogenous mix (para 1.4.2)
where required install a drainage layer of clean stone and cover with a sheet of
geotextile material (para 1.7.1)
where instructed install the pit drainage system and connect to existing drains.
This work must be carried out in full consultation with City of Newcastle upon
Tyne Engineering Services departmentt.
where instructed, and adjacent to known service runs install a ‘root director’ or
root barrier (see Diagram No. 4 & para 1.6.4)
check the correct depth of the excavated pit by use of a straight edge against
the stem of the tree, or by measurement if the tree is too heavy to lift easily (para
1.13.2). Remember to take into account any proposed surface treatment such as
tree grilles and increase the depth accordingly.
where no drainage layer has been installed break up the base of the pit with a
fork. Where no root director has been installed scarify the sides of the pit with a
fork.
20
lower tree into the centre of the pit and ensure that it is set vertical.
check, with a straight edge that the tree is sitting at the correct depth. If it is not,
remove the tree and adjust the base levels accordingly.
staking:
- for bare root trees position the stakes / stake so that the root system is not
damaged, remove the tree and drive the stakes so that they are firm and to the
correct depth (see Diagram No.’s 2A, 2B & 2C, para 1.8.3). Re-set the tree
between or adjacent to the stakes / stake.
- for rootballed trees position the stakes, for either above ground or below
ground systems, adjacent to but clear of the rootball and drive them until the
wires hold the tree firmly and vertically with no movement at the base of the
rootball (see Diagram No.’s 1A, 1B, & 1D, para 1.8.3 & 1.8.7)
backfill the pit with topsoil or topsoil / compost mix in layers 300 mm deep and
lightly firm each layer (para 1.5.2). With bare roots ensure that the soil is
carefully worked around the roots and air pockets are eliminated.
Install an irrigation / aeration pipe after backfilling to one third depth of the
rootball and install prior to completing the backfilling (para 1.9.3)
above ground stakes – tie the tree to the stakes, at 600 mm above ground level
or just below the lowest branches of the tree depending on the system being
used, with rubber ties and spacers or canvas hosing (see Diagram No’s1E, 2A,
2B & 2C, para. 1.8.4), and cut off the top of the stakes if damaged during driving
or of excess length.
apply 25 ltrs of water over the surface of the pit (para 1.9.2)
install surface treatment if specified.
2.02 Planting in new ground –
Prior to work commencing on site:
obtain service and utility information and complete a visual inspection for
possible constraints to the proposed scheme (para 1.3.1)
carry out a risk management assessment for site operatives and users during
the entire planting and maintenance operations of the trees (para 1.3.2)
consult existing residents / occupiers of adjacent properties and inform them of
the draft proposals and programme
make any necessary amendments to the proposals in response to comments
following the public consultation
21
Site works:
excavate the area to be topsoil to at least 1.1m deep (final depth will require an
allowance for the thickness of the specified paving / surface treatment) (See
1.4.4 for required topsoil volumes).
install a drainage layer, 200 mm deep of clean stone and cover with a sheet of
geotextile material (para 1.7.1) If necessary, install pipe drainage from the base
of the stone layer and connect to an adequate outflow point.
where specified and where there are adjacent foundations or services install a
root barrier at least 1.2m deep to the sides of the pit, ensuring 300 mm overlap
at joints, or root protector (see Diagram No’s 4 & 6, paras. 1.6.2 & 1.6.4)
install approved topsoil or, if specified, ‘load-bearing tree soil’ into the planting
area in 300 mm deep layers. Topsoil must be lightly compacted by treading each
layer prior to spreading the next layer. ‘Tree soil’ must be compacted by using
an ‘elephants foot’ type whacker plate - one pass over the entire surface of the
first two layers, two passes over the surface of the top layer, compacted to 2 kg /
cm2 and measured at a compaction of 0.2 with a penetrometer. (para 1.5.3)
after backfilling the planting area cover the topsoil with plastic sheeting or
tarpaulin to protect from wet weather until the finished surface is constructed.
excavate that number of tree pits which can be planted during the same day.
Any open pits must not be left uncovered when operatives leave the site.
Provision must be made to cover open pit with a board and warning tape erected
around the area.
check the correct depth by use of a straight edge against the stem of the tree, or
by measurement if the tree is too heavy to lift easily (para 1.13.2). Remember to
take into account any proposed surface treatment such as tree grilles and
increase the depth accordingly.
lower tree into the centre of the pit and ensure that it is set vertical.
check, with a straight edge that the tree is sitting at the correct depth. If it is not,
remove the tree and adjust the base levels accordingly.
staking:
- for bare root trees position the stakes / stake so that the root system is not
damaged, remove the tree and drive the stakes so that they are firm and to the
correct depth (para 8.03). Re-set the tree between or adjacent to the stakes /
stake.
22
- for rootballed trees position the stakes, for either above ground or below
ground systems, adjacent to but clear of the rootball and drive them until firm,
and for underground support systems until the wires hold the tree firmly and
vertically with no movement at the base of the rootball (see Diagram No.’s 1A,
1B, 1D & 1E, para 1.8.3 & 1.8.7)
backfill the pit with topsoil or topsoil / compost mix in layers 300 mm deep and
lightly firm each layer (para 1.5.2). With bare roots ensure that the soil is
carefully worked around the roots and air pockets are eliminated.
Where an irrigation / aeration pipe is to be installed, backfill to one third depth of
the rootball and install prior to completing the backfilling (see Diagram No. 1A,
1B, 1C, 1D, 2D, 3B, para 1.9.3)
above ground stakes – tie the tree to the stakes, at 600 mm above ground level
or just below the lowest branches of the tree depending on the system being
used, with rubber ties and spacers or canvas hosing (para 1.8.4), and cut off the
top of the stakes if damaged during driving or of excess length.
apply 25 ltrs of water over the surface of the pit (para 1.9.2)
install surface treatment if specified.
23
PART 3
3.00 SPECIFICATION
Contents: 3.1 General Specification and Requirements for Tree Planting
3.2 Planting Bareroot Trees (general guidance)
3.3 Packaging and Handling of Semi-Mature Trees
3.4 Post Planting – Maintenance and Aftercare
3.5 Rootballed Trees in Grass or Shrub Areas – Underground Support
3.6 Rootballed Trees in Paving – Underground Support
3.7 Rootballed Trees in Grass or Shrub Areas – Double Stakes
3.8 Bareroot Trees in Grass or Shrub Areas – Triple Stakes with Mesh
Guards
3.9 Bareroot Trees in Paved Areas – Triple Stakes with Mesh Guards
3.10 Bareroot Trees in Grass or Shrub Areas – Single and Double Stakes
(no tree guard)
3.11 Trees in Paving – Resin Bound Aggregate Surface Finish to Tree Pit
including Raised Edge Surround
3.12 Trees in Paving – Construction of Reinforced Paving Surround
3.13 Trees in Paving – Root Barrier / Root Director
24
3.00 SPECIFICATIONS 3.1 GENERAL SPECIFICATION AND REQUIREMENTS FOR TREE PLANTING
The following British Standards apply:
BS 4428:1989 Code of practice for general landscape operations (excluding hard
surfaces)
BS 4043:1989 Recommendations for transplanting root-balled trees
1. PLANTING SEASON & CONDITIONS –
Carry out the work while soil and weather conditions are suitable for the
relevant operations. Bare root and rootballed trees should normally only be
transplanted during the recognised dormant season – beginning of November to
the end of February.
Planting outside the period above - it may be possible to plant bare root or
rootballed trees in March but this is dependent on the tree species involved and
the prevailing weather conditions and adequate provision of watering. There
must be no assumption that planting can be continued after February and the
Contractor will seek advice if programming of works dictates planting at this
time of the year.
Tree planting between April and November - usually only possible by using
container grown material. The tree will be in leaf and adequate provision must
be made for irrigation at the time of planting and for continuing throughout the
summer months.
2. MACHINES AND TOOLS –
Use only machinery and tools suitable for the site conditions and the work to be
carried out. Use hand tools around trees, plants and in confined spaces where it
is impracticable to use machinery.
3. WATER –
to be provided for watering-in immediately following planting at 25 ltrs. / tree
25
4 NOTICE PRIOR TO PLANTING –
Make advance arrangements with the Client to give him the opportunity of being
present during:
Setting out
During excavation of the tree pits.
Planting of trees into previously dug pits
Each site visit during maintenance period.
5 STORAGE –
Plants which are not to be planted on day of delivery to site to be stored as follows:
Root balled plants: Place close together and cover root balls with sand, moist
compost/soil or wet straw.
Bare root plants: for short periods, up to three days, they can be stored in
strong black plastic bags in a cool location. For longer periods the roots must be
temporarily covered by soil in a shallow trench (‘heeled-in’)
6 TRANSPORTATION AND MOVING TREES -
In accordance with BS 4043:1989.
Machinery for moving the trees must be appropriate for the size and weight of
the trees.
Supporting slings must be located under the rootball, not around the stem.
Branches to be tied in to avoid damage during transport.
7. DELIVERY -
All trees must be stacked in such a way that breakage or crushing, by weight of
the trees above or the securing of ropes will not occur.
Where an open vehicle is used for delivery the whole consignment of trees must
be completely covered with opaque windproof sheeting and secured.
Trees must not be transported by rail or post.
Mishandling of trees during lifting, packaging or delivery resulting in damage to
the root system or aerial parts of the tree may result in rejection after re-
inspection of the trees on arrival at the landscape contractors nursery or the
site.
26
8. TREATMENT OF WOUNDS –
any minor damage that occurs to branches during handling shall be cut cleanly
back to sound wood using sharp, clean tools. Position cuts so that water will not
collect on the cut area.
Do not apply fungicide or sealant unless instructed by the Contract
Administrator.
Major damage to branches or damage to the trunk must be reported immediately
to the CA and the tree should remain unplanted, but with the roots protected,
until an inspection has been made and a decision made on whether to replace
the tree.
10 PROTECTION OF SURROUNDING GRASS –
existing grass during planting operations by laying boards or sheeting. Do not
place excavated material directly on to grass.
11. TREE PIT CONSTRUCTION –
excavate by hand or mechanical means to the sizes quoted in the detailed
specifications. Ensure that the base of the pit is broken up and the sides are
scarified.
Do not excavate pits during periods of extreme weather or allow the pits to fill
with standing water. If, after excavation, water appears to be rising into the base
of the pit inform the CA and wait for further instructions. A tree shall not be
planted into a site where there is a high water table or other drainage problems
unless adequate drainage can be provided.
12. PLANTING –
protect bare root trees during the planting operation. Roots must be kept
covered by sacking or polythene to prevent from drying out.
Immediately after planting water the tree root area with approximately 25 litres
of water to ensure that the contact between the root or rootball and the planting
soil is uniformly moist.
Refer to the applicable specification for details of planting the root type being
used.
27
13. CROWN PRUNING AT PLANTING –
Unless previously carried out by the supplying nursery provision should be made
for thinning the crown of the tree at the time of planting by up to 25% or as
directed by the Contract Administrator. Thinning should be made to lateral
branches and weak side growth. The leading shoot must not be pruned.
14. SURPLUS MATERIAL –
including subsoil, stones, debris, wrapping material and prunings to be removed
from site. Leave the site clean and tidy.
28
3.2 SPECIFICATION - PLANTING BAREROOT TREES (GENERAL GUIDANCE) BS 4043 applies.
1. PIT SIZE AND CONSTRUCTION -
Pits: shall be 300 mm wider than the spread of the root and with a minimum size
of 800 x 800 mm. Minimum excavated depth of 600 mm. Where necessary the
depth shall be increased to accommodate the depth of the root and to obtain the
correct planting level.
Break up bottom of pit to 150 mm deep and scarify the sides of the pit with a
fork.
2. PLANTING -
Protective packaging – trees must be delivered to site covered and the roots
protected from desiccation at all times and shall be removed from the packaging
immediately prior to planting. Trees whose roots show signs of having been
damaged or drying out should be rejected and returned to the supplier.
Horticultural Trade Association advice requires that bare root trees must be
placed into co-extruded bags immediately they are lifted. The tree must be
stored in the co-extruded bags, delivered, and kept on site in the same bags.
(Co-extruded bags are white inside and black on the outside and made from
heavy gauge polythene).
Trees which are delivered to site in an unprotected or insufficiently protected
manner must be rejected and returned to the supplier.
After excavation, but before driving the stakes, hold the tree in the pit to assess
the correct depth. A straight-edge laid horizontally across the pit from each side
will enable the correct position of the root collar to be established in relation to
the existing ground level.
Plant trees upright and, unless otherwise instructed, in centre of pit.
Backfill the pit to a sufficient depth so as to support the tree at the correct level.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the top surface of the surrounding soil.
Establish the position of the stake or stakes so as not to interfere with the roots,
remove the tree then drive the stakes to make them firm. Burred or split stakes
shall be cut off at a point below the damage.
29
Locate the tree at the correct level and, in paved areas or in mown grass, fit an
irrigation/aeration pipe.
Backfill the pit with specified material in 150 mm layers, shaking the tree slightly
to ensure thorough and even distribution through the roots. Tread the last two
last layers lightly to consolidate.
Fix the tree to the stake using a proprietary tree-tie with a spacing device to
prevent the tree rubbing against the stake. The tie shall be nailed to the stake
with one galvanised ‘clout nail‘, minimum 25 mm long and with 10 mm heads, to
prevent the tie slipping.
3. DRAINAGE & AERATION UNIT -
Proprietary system installed in accordance with the manufacturers instructions or
60 mm perforated plastic drainage pipe of sufficient length to encircle the
rootball at approximately 2/3rds depth and reach vertically to the surface of the
pit. A removable perforated end cap to be placed on the surface end of the pipe
to prevent blockage by debris.
4. SUPPORTING BAREROOT TREES:
Stakes: softwood, peeled chestnut or larch, free from projections and large edge
knots with one end pointed.
Minimum stake sizes:
Staking height / Tree size Overall Length of Stake Cross Section of Stake
Light Standard / Heavy
Standard -
at approximately 1/3rd
height of tree above
ground level
1800
75 – 100 mm
Light Standard – Heavy
Standard
at a point immediately
below the lowest branches
2700
75 – 100 mm
30
Extra Heavy Standard and
above at approximately
1/3rd height of tree above
ground level
1800
100mm
Extra Heavy Standard
and above
at a point immediately
below the below the lowest
branches
2700
100 mm
5. WATERING:
At planting ensure that all trees are given at least 25 ltrs. of water, applied over the
surface of the planting pit, to ensure thorough soaking of the rootball and the
surrounding ground.
6. CROWN PRUNING
Unless previously carried out by the supplying nursery provision should be made for
thinning the crown of trees immediately prior to planting by up to 25%. Thinning
should be made to lateral branches and weak side growth and include the removal
of any damaged branches. The leader shoot must not be pruned.
7. SITE CLEANLINESS
Remove soil from all hard surfaces and grassed areas and leave the works in a
clean tidy condition at Practical Completion. Adjacent surfaces must be protected
during the course of the works by laying timber sheeting or heavy gauge polythene
onto which arisings can be temporarily placed.
31
3.3 SPECIFICATION FOR THE PACKAGING AND HANDLING OF SEMI-MATURE TREES
1. PACKAGING
Packaging must be adequate for the protection of the trees and such as to
avoid heating-up or drying-out and must conform to the following:-
Root-balled and container grown trees must not be bundled.
Root-balls must be moist, supported by elastic banding, string netting or
stronger material where required to prevent collapse. The rootball must be
protected against drying-out by wrapping firmly with moisture retentive, porous
material such as sacking. Where wire-netting is used to support the rootball,
any moisture-retentive material must be outside the netting.
All extra heavy standard, heavy standard, selected standard and standard trees
must be individually packaged.
Each packaged tree must be individually labelled with species, variety size and
where appropriate the quantity, whether bare-root, root-balled or container
grown.
Lateral branches and the head of the tree must be “tied-in” with ribbon or other
supple materials, but not coarse string which can cut into the bark, to protect the
crown from damage during handling and delivery and the planting process.
2. DELIVERY
All trees must be stacked in such a way that breakage or crushing, by weight of
the trees above or the securing of ropes will not occur.
Where an open vehicle is used for delivery the whole consignment of trees must
be completely covered with opaque windproof sheeting and secured.
Trees must not be transported by rail or post.
Mishandling of trees during lifting, packaging or delivery resulting in damage to
the root system or aerial parts of the tree will be subject to rejection, upon re-
inspection of the trees on arrival at the landscape contractors nursery or the
site.
32
3.4 SPECIFICATION - POST PLANTING MAINTENANCE AND AFTERCARE
The period of time for which the contractor is responsible for the defects and
maintenance of the tree shall be a minimum of 3 years unless otherwise specified.
1. PLANTING MAINTENANCE –
During the Defects Liability Period and specified maintenance period carry out the
following operations:
Make visits at approximately monthly intervals during the growing season and as
necessary to fulfil the requirements of this specification.
Inform CA at least three days in advance of any maintenance operations to be
undertaken.
During the maintenance visits carry out the following checks:
Check condition of stakes, ties, guys and guards. Replace broken or missing
items and adjust ties if necessary to prevent rubbing of bark.
Trees that are supported by underground guys should be checked for stability. If
necessary the wires will need to be exposed and tightened.
Cut back any damaged bark to a clean healthy area.
Trees in grass must be kept clear of grass or weed growth over an area of 1m
diameter for trees up to 30cm diam. girth, 2m diameter for bigger trees, by hand
during the first year after planting or by approved herbicides during subsequent
years.
Prune trees to remove dead or dying and diseased wood and suckers and to
promote healthy growth and natural shape. Pruning should take place between
November and the end of February or early July to early August. Vandalised,
ripped and hanging branches shall be removed immediately whatever the time
of year.
2. WATERING –
Water as indicated below. Visits to be recorded and CA informed.Once during the
maintenance period, in March or April, apply liquid fertilizer to each tree, in
accordance with the manufacturer’s instructions.
during the establishment period arrangements should be made to provide at
least 90 litres of water per tree at fortnightly intervals during the period
33
1st May to 30th September unless weather conditions dictate otherwise. It may
be necessary to commence watering earlier during a dry Spring. Where fitted,
watering should be via the irrigation pipe otherwise over the area of the planting
pit.
3. FAILURES OF PLANTING –
Where the contractor is responsible for the replacement of trees that die during the
specified maintenance period the following shall be applied:
Any trees which are dead, dying or otherwise defective at the end of the Defects
Liability Period will be regarded as defects due to materials or workmanship not
in accordance with the Contract. They must be replaced by approved equivalent
trees at the next suitable planting season unless otherwise instructed. This will
not apply if the defects are caused by malicious damage after Practical
Completion unless stated otherwise in the Contract.
The Defects Period for trees up to and including ‘Standard’ size will be 12
months.
The Defects Period for semi mature trees will be 36 months.
All trees will be assessed for growth throughout the defects period. A detailed
inspection will be undertaken during July/August, reporting by 31st August each
year, of the first, second and third year of the defects period. If, in the opinion of
the CA, the trees are dead, making insufficient growth or showing crown die-
back, or have a percentage of dormant buds over and above that which could
reasonably be expected, then they shall be replaced under the Defects Liability
and to all relevant specifications.
If it becomes necessary to replace a tree or trees the Contractor will be required
to arrange for the protection of all paved and grass areas surrounding the trees
and on the access to them, and for lifting and reinstating tree grilles and guards
if fitted. Protection for surrounding areas will be by the use of plywood boards
and sheeting of sufficient dimensions to cover the area of the work.
After replanting, damaged areas of whatever material will be reinstated to the
satisfaction of the CA.
34
3.5 SPECIFICATION – ROOTBALL TREES IN GRASS OR SHRUB AREAS, UNDERGROUND SUPPORT
BS 4043 & BS 4428 apply
Refer to Diagram No. 1A and 1C
1. PIT SIZE AND CONSTRUCTION -
Pits: shall be 600 mm wider than the diameter of the rootball with a minimum
size of 900 x 900 mm. Minimum depth to be 750 mm. Where necessary the
depth shall be increased to accommodate the depth of the rootball and to obtain
the correct planting level. Break up bottom of pit to 150 mm deep and scarify the
sides of the pit with a fork.
2. PLANTING –
Remove any moisture-retentive material used to prevent the rootball drying out
during transport from the nursery but protect the rootball from sun and wind
during the planting operation.
Move the wire mesh support and root packing away from the trunk of the tree
but do not cut away from the main rootball, the integrity of the wire mesh must
not be damaged. Do not cut the wire mesh.
Plant trees upright and, unless otherwise instructed, in centre of pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the finished top surface of the planting medium. A straight edge
placed across the pit at finished surface level and adjacent to the tree will assist
in gauging the correct level. If necessary, the depth of the pit must be adjusted
to ensure the correct planting level.
Install below-ground irrigation and aeration system e.g. Greenleaf ‘Root Rain
Urban’ ensuring that the top of the filler pipe is flush with finished surface levels.
Backfill around the rootball with specified material in 150 mm layers, treading
lightly to compact each layer to a level approximately halfway up the side of the
rootball.
The underground support should be installed prior to completing the backfilling
of the pit.
Immediately after planting the tree shall be watered with approximately 25 ltrs. of
water to ensure that the contact of soil between the rootball and backfill material
is uniformly moist.
35
3. UNDERGROUND SUPPORT -
Driven stake system (Diagram No. 1A) -
1 No. underground support per tree for trees up to 8m high. For trees 8m and
above two support systems should be used.
Stake and wire system comprising of 3No. timber stakes, 1.75m long x 75-
100mm diam., peeled but untreated with preservative and free of knots likely to
cause weak points. Galvanised wire, 5mm diam. multi-strand attached to each
stake with staples and to form a triangular cage over the rootball.
Stakes shall be at equi-distant spacing around the rootball and driven at an
angle under the rootball leaving at least 500 mm above the level of the pit for
final tensioning. Attach the wire as described, bringing it as tight as possible by
means of fencing pliers or similar. Final tightening of the wire over the top
surface of the rootball mesh is achieved by continuing to drive the stakes until
the wire is as tight as possible.
After final tightening the top of the stakes shall be cut off below finished surface
level.
For trees in excess of 8m high the above specification applies but with the use of
two independent kits per tree i.e. 6No. stakes.
Where ground conditions below the pit prevent the use of driven timber stakes then
one of the following may be employed -
Ground anchorage system such as:
‘Platipus Systems Rootball Fixing Kit’
Supplied by Platipus Anchors Limited, Perrywood Business Park, Honeycrock Lane,
Salfords, Nr Redhill, Surrey RH1 5DZ Tel: 01737 762300
All work to be manufacturers instructions.
Deadman System (Diagram No. 1C) 1 No. underground support system comprising:
2No. deadmen located at opposite sides of the rootball. Deadmen shall be timber
or concrete, rectangular in section and of sufficient mass to prevent movement
when
buried below the soil. (For example, for a tree 5m tall a timber deadman should
have a section approximately 150mm wide x 100mm thick x 1200 long.)
The deadmen and wire must be fixed prior to backfilling the pit or placing the tree.
36
5mm diam. multi-strand wire stapled around each deadman shall be tensioned by
turnbuckle or ratchet devices after the tree is in its final position.
37
3.6 SPECIFICATION – ROOTBALL TREES IN PAVING, UNDERGROUND SUPPORT
BS 4043 & BS 4428 apply
Refer to Diagram No. 1A or 1C
1. PIT SIZE AND CONSTRUCTION -
Pits: shall be 600 mm wider than the diameter of the rootball with a minimum
size of 900 x 900 mm. Minimum depth of topsoil to be 900 mm, the depth of the
excavated pit will be sufficient to accommodate the rootball and to obtain the
correct planting depth. Break up bottom of pit to 150 mm deep and scarify the
sides of the pit with a fork.
2. PLANTING –
Any moisture-retentive material used to prevent the rootball drying out during
transport from the nursery must be completely removed prior to planting but
protect the rootball from sun and wind during the planting operation.
Move the wire mesh support and root packing shall be away from the trunk of
the tree but do not cut away from the main rootball, the integrity of the wire mesh
must not be damaged. Do not cut the wire mesh.
Plant trees upright and, unless otherwise instructed, in centre of pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the finished top surface of the planting medium. A straight edge
placed across the pit at finished surface level and adjacent to the tree will assist
in gauging the correct level. If necessary, the depth of the pit must be adjusted
to ensure the correct planting level.
Backfill around the rootball with specified material in 150 mm layers, treading
lightly to compact each layer to a level approximately halfway up the side of the
rootball.
The underground support should be installed prior to completing the backfilling
of the pit.
Immediately after planting the tree shall be watered with approximately 25 ltrs. of
water to ensure that the contact of soil between the rootball and backfill material
is uniformly moist.
38
3. UNDERGROUND SUPPORT -
Driven stake system (Diagram No. 1A)
1 No. underground support per tree for trees up to 8m high. For trees 8m and
above two support systems should be used.
Stake and wire system comprising of 3No. timber stakes, 1.75m long x 75-
100mm diam., peeled but untreated with preservative and free of knots likely to
cause weak points. Galvanised wire, 5mm diam. multi-strand attached to each
stake with staples and to form a triangular cage over the rootball.
Stakes shall be at equi-distanct spacing around the rootball and driven at an
angle under the rootball leaving at least 500 mm above the level of the pit for
final tensioning. Attach the wire as described, bringing it as tight as possible by
means of fencing pliers or similar. Final tightening of the wire over the top
surface of the rootball mesh is achieved by continuing to drive the stakes until
the wire is as tight as possible.
After final tightening the top of the stakes shall be cut off below finished surface
level.
For trees in excess of 8m high the above specification applies but with the use of
two independent kits per tree i.e. 6 No. stakes.
Where ground conditions below the pit prevent the use of driven timber stakes then
one of the following may be employed -
Ground anchorage system such as:
‘Platipus Systems Rootball Fixing Kit’
Supplied by Platipus Anchors Limited, Perrywood Business Park, Honeycrock Lane,
Salfords, Nr Redhill, Surrey RH1 5DZ Tel: 01737 762300
All work to be manufacturers instructions.
Deadman System (Diagram No. 1C) 1 No. underground support system comprising:
2 No. deadmen located at opposite sides of the rootball. Deadmen shall be timber
or concrete, rectangular in section and of sufficient mass to prevent movement
when buried below the soil. (For example, for a tree 5m tall a timber deadman
should have a section approximately 250mm wide x 100mm thick x 1500 long.)
The deadmen and wire must be fixed prior to backfilling the pit or placing the tree.
5mm diam. multi-strand wire stapled around each deadman shall be tensioned by
turnbuckle or ratchet devices after the tree is in its final position.
39
5. DRAINAGE / AERATION UNIT –
The drainage / aeration pipe such as Greenleaf ‘Root Rain Urban’ should be
installed after the underground support to prevent damage to the pipe.
The drainage / aeration pipe, 60 mm diameter, shall fully encircle the rootball at
approximately 2/3 rds its depth with a vertical tail reaching to the surface of the
pit. A removable perforated end cap should be used at ground level to prevent
debris blocking the pipe.
For semi – mature trees with a rootball in excess of 1200 mm diameter the pipe
should form a spiral with at least two complete turns encircling the rootball.
40
3.7 SPECIFICATION – ROOTBALL TREES IN GRASS OR SHRUB AREAS, DOUBLE STAKES BS 4043 & 4428 apply.
Refer to Diagram No. 1E
1. PIT SIZE AND CONSTRUCTION –
Pits: shall be 600 mm wider than the diameter of the rootball with a minimum
size of 900 x 900 mm. Minimum depth to be 750 mm. Where necessary the
depth shall be increased to accommodate the depth of the rootball and to obtain
the correct planting level.
Break up bottom of pit to 150 mm deep and scarify the sides of the pit with a
fork.
2. PLANTING -
Remove any moisture-retentive material used to prevent the rootball drying out
during transport from the nursery but protect all roots from sun and wind during
the planting operation.
Move the wire mesh support and root packing shall be away from the trunk of
the tree but do not cut away from the main rootball, the integrity of the wire mesh
must not be damaged. Do not cut the wire mesh.
Plant trees upright and, unless otherwise instructed, in centre of pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the finished top surface of the planting medium. A straight edge
placed across the pit at finished surface level and adjacent to the tree will assist
in gauging the correct level. If necessary the depth of the pit must be adjusted to
ensure the correct planting level.
Backfill around the rootball with specified material in 150 mm layers, treading
lightly to compact each layer to a level approximately one third up the side of the
rootball.
Install the double stake support system in accordance with the specification
below.
Immediately after planting the tree shall be watered over the soil surface with
approximately 25 ltrs. of water to ensure that the contact of soil between the
rootball and backfill material is uniformly moist
41
3. DOUBLE STAKE SUPPORT-
Staking kit comprising 2No. stakes 2 m long x 70 mm approximate diameter and
2No. ties.
Stakes shall be peeled, free of stubs or large knots and untreated with
preservative.
Ties shall be either proprietary rubber strapping 25 – 50 mm wide or
rubber/nylon hosepipe.
Stakes shall be set at an equal distance from the trunk of the tree and clear of
the rootball. Use a ‘pinch’ bar or similar to produce a vertical guide hole then
drive the stake until firm and at least 300 mm below the base of the tree pit. The
final height of the stake shall be approximately one third the clear stem height of
the tree.
Loop the tie around the trunk, one from each side of, and firmly nail to each
stake with 2No. galvanised clout nails. Ties to be fixed as tight as possible to
prevent the tree moving at the base of the trunk.
42
3.8 SPECIFICATION – BAREROOT TREES IN GRASS OR SHRUB AREAS - TRIPLE STAKES To be used for bare root trees with a stem girth of 18 cm or above
BS 4428 applies.
Refer to Diagram No. 2C
1. PIT SIZE AND CONSTRUCTION -
Pits: shall be 600 mm wider than the root spread of the tree with a minimum
width of 800 x 800 mm. Minimum depth to be 600 mm. Where necessary the
depth shall be increased to accommodate the depth of the root and to obtain the
correct planting level.
Break up bottom of pit to 150 mm deep and scarify the sides of the pit with a
fork.
2. PLANTING -
Remove any moisture-retentive material used to prevent the root drying out
during transport from the nursery but protect all roots from sun and wind during
the planting operation.
Prior to installing the stakes place the tree into the pit to check the correct
planting depth, that the pit can accommodate the fully spread root system and
place the stake / stakes in positions that will not damage the roots. Remove the
tree and cover the roots with protective material.
Install the stake support system in accordance with the specification below.
Plant trees upright and, unless otherwise instructed, in centre of pit, spreading
the roots carefully and evenly over the base of the pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the finished top surface of the planting medium. A straight edge
placed across the pit at finished surface level and adjacent to the tree will assist
in gauging the correct level. If necessary the depth of the pit must be adjusted to
ensure the correct planting level.
Backfill around the root, gently shaking the tree will aid settlement and ensure
that no air spaces exist, with specified material in 150 mm layers, treading lightly
to compact each layer.
43
Immediately after planting the tree shall be watered over the soil surface with
approximately 25 ltrs. of water to ensure that the contact of soil between the
roots and backfill material is uniformly moist.
3. TRIPLE STAKE SUPPORT -
Staking kit comprising 3No. stakes 2 m long x 70 mm approximate diameter and
3No. ties.
Stakes shall be peeled, free of stubs or large knots and untreated with
preservative.
Ties shall be either proprietary rubber strapping 25 – 50 mm wide or
rubber/nylon or canvas hosepipe.
Stakes shall be set at an equal distance from the trunk of the tree and clear of
the rootball and at equi-distant spacing. Angle each stake back from the vertical
by approximately 5 deg. Use a ‘pinch’ bar or similar to produce a guide hole then
drive the stake until firm and at least 300 mm below the base of the tree pit. The
final height of the stake shall be approximately one third the clear stem height of
the tree.
Loop the tie around the trunk, one from each side of, and firmly nail to each
stake with 2No. galvanised clout nails. Ties to be fixed as tight as possible to
prevent the tree moving at the base of the trunk.
After driving the stake, if the top has split or burred this should be cut back to
sound wood prior to fixing the tie.
44
3.9 SPECIFICATION – BARE ROOT TREES IN GRASS OR SHRUB AREAS, TRIPLE STAKES WITH MESH GUARD To be used for bare root trees in locations likely to receive high levels of
interference and damage.
BS 4043 applies
Refer to Diagram No. 3A
1 . PIT SIZE AND CONSTRUCTION -
Pits: shall be 600 mm wider than the root spread of the tree with a minimum
width of 800 x 800 mm. Minimum depth to be 600 mm. Where necessary the
depth shall be increased to accommodate the depth of the root and to obtain the
correct planting level.
Break up bottom of pit to 150 mm deep and scarify the sides of the pit with a
fork.
2 PLANTING –
Remove any moisture-retentive material used to prevent the root drying out
during transport from the nursery but protect all roots from the sun and wind
during the planting operation.
Prior to installing the stakes place the tree into the pit to check the correct
planting depth, that the pit can accommodate the fully spread root system and
place the stakes in positions that will not damage the roots. Remove the tree
and cover the roots with protective material.
Install the stake support system in accordance with the specification below.
Plant trees upright and, unless otherwise instructed, in centre of pit, spreading
the roots carefully and evenly over the base of the pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the finished top surface of the planting medium. A straight edge
placed across the pit at finished surface level and adjacent to the tree will assist
in gauging the correct level. If necessary the depth of the pit must be adjusted to
ensure the correct planting level.
Backfill around the root, gently shaking the tree will aid settlement and ensure
that no air spaces exist, with specified material in 150 mm layers, treading lightly
to compact each layer.
45
Immediately after planting the tree shall be watered over the soil surface with
approximately 25 ltrs. of water to ensure that the contact of soil between the
roots and backfill material is uniformly moist.
3. TRIPLE STAKE SUPPORT -
Staking kit comprising 3No. stakes 2.7 m long x 70 mm approximate diameter
and 3No. ties.
Stakes shall be peeled, free of stubs or large knots and untreated with
preservative.
Ties shall be either proprietary rubber strapping 25 – 50 mm wide or
rubber/nylon hosepipe.
Stakes shall be set at an equal distance (approximately 300 mm) from the trunk
of the tree and clear of the rootball and at equi-distant spacing. Use a ‘pinch’ bar
or similar to produce a vertical guide hole then drive the stakes until firm and at
least 300 mm below the base of the tree pit. The final height of the stake shall be
just below the lowest branches of the tree.
Loop the ties, at 400 mm below the top of the stakes, around the trunk and firmly
nail to each stake with 2No. galvanised clout nails. Ties to be fixed as tight as
possible to prevent the tree moving at the base of the trunk.
After driving the stakes, if the top has split or burred this should be cut back to
sound wood prior to fixing the tie.
4. MESH GUARD –
The guard shall be formed from a sheet of 50 x 50 mm x 2.5 gauge welded
mesh, plastic coated in black or green.
The mesh shall be fixed to the outside of each stake to form a cage 1500 mm
high with a 200 mm gap at the base.
Fixing shall be with galvanised staples, 4No. to each stake at an equal distance
between the top and the bottom of the mesh.
The cut ends of the mesh must be bent back inside the cage to remove the
possibility of sharp snag ends.
46
3.10 SPECIFICATION – BAREROOT TREES IN GRASS OR SHRUB AREAS, SINGLE AND DOUBLE STAKES (NO TREE GUARD)
BS 4428 applies.
Refer to Diagram No. 2A (single stake) & 2B (double stake)
1. PIT SIZE AND CONSTRUCTION
Pits: shall be 600 mm wider than the root spread of the tree. Minimum depth to
be 600 mm. Where necessary the depth shall be increased to accommodate the
depth of the root and to obtain the correct planting level. Break up bottom of pit
to 150 mm deep and scarify the sides of the pit with a fork.
2. PLANTING -
Remove any moisture-retentive material used to prevent the root drying out
during transport from the nursery but protect all roots from sun and wind during
the planting operation.
Prior to installing the stakes place the tree into the pit to check the correct
planting depth, that the pit can accommodate the fully spread root system and
place the stake / stakes in positions that will not damage the roots. Remove the
tree and cover the roots with protective material.
Install the stake support system in accordance with the specification below.
Plant trees upright and, unless otherwise instructed, in centre of pit, spreading
the roots carefully and evenly over the base of the pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be at the finished top surface of the planting medium. A straight edge
placed across the pit at finished surface level and adjacent to the tree will assist
in gauging the correct level. If necessary the depth of the pit must be adjusted to
ensure the correct planting level.
Backfill around the root, gently shaking the tree will aid settlement and ensure
that no air spaces exist, with specified material in 150 mm layers, treading lightly
to compact each layer.
Immediately after planting the tree shall be watered over the soil surface with
approximately 25 ltrs. of water to ensure that the contact of soil between the
roots and backfill material is uniformly moist.
47
3. STAKE SUPPORT –
Single staking kit comprising 1No. stake 2.7m long x 70 mm approximate
diameter and 1No. tie.
Double staking kit comprising 2No. stakes 2 m long x 70 mm approximate
diameter and 2No. ties.
Stakes shall be peeled, free of stubs or large knots and untreated with
preservative.
Ties shall be proprietary rubber or plastic ties with a spacing block located
between the tree and the stake. The tie must be securely fixed to the stake with
a galvanised clout nail.
Stakes shall be set at a point that does not interfere with the roots of the tree.
Use a ‘pinch’ bar or similar to produce a vertical guide hole then drive the stake
until firm and at least 300 mm below the base of the tree pit. The final height of
the stake shall be approximately one third the clear stem height of the tree or
just below the lowest branches, which ever is appropriate to the site.
After driving the stake, if the top has split or burred this should be cut back to
sound wood prior to fixing the tie.
48
3.11 SPECIFICATION – ROOTBALL TREES IN PAVING, UNDERGROUND SUPPORT AND RESIN-BOUND AGGREGATE SURFACE FINISH BS 4043 & BS 4428 apply
Refer to Diagram No. 1B (where tree pit surface will be flush with surrounding
paving), or No. 5 (where a raised surround to the tree pit is required)
For planting in a continuous soil trench also refer to Specification 3.12
1. PIT SIZE AND CONSTRUCTION -
Pits: the minimum size of the tree pit will be 1200 x 1200 x 900mm deep.
Excavate a planting hole 600 mm wider than the diameter of the rootball. The
depth of the excavated pit will be sufficient to accommodate the rootball and to
obtain the correct planting depth. Break up bottom of pit to 150 mm deep and
scarify the sides of the pit with a fork.
2. PLANTING –
Any moisture-retentive material used to prevent the rootball drying out during
transport from the nursery must be completely removed prior to planting but
protect the rootball from sun and wind during the planting operation.
The wire mesh surrounding the rootball must not be cut or loosened except
around the stem of the tree where it should be pulled clear to ensure no damage
to the tree.
Plant trees upright and, unless otherwise instructed, in centre of pit.
Planting depth – the natural thickening between the trunk and the root collar
shall be 75mm below the finished levels of the surrounding paving. A straight
edge placed across the pit at finished surface level and adjacent to the tree will
assist in gauging the correct level. If necessary, the depth of the pit must be
adjusted to ensure the correct planting level.
Install the drainage aeration unit (see 3.11.5 below) and backfill around the
rootball with specified material in 150 mm layers, treading lightly to compact
each layer to a level approximately halfway up the side of the rootball.
The underground support should be installed prior to completing the backfilling
of the pit.
49
Complete backfilling the pit, the finished soil level shall be 125mm below the
finished levels of the surrounding paving.
Immediately after planting the tree shall be watered with approximately 25 ltrs. of
water to ensure that the contact of soil between the rootball and backfill material
is uniformly moist.
3. UNDERGROUND SUPPORT -
Driven stake system (Diagram No. 1B)
1 No. underground support per tree for trees up to 8m high. For trees 8m and
above two support systems should be used.
Stake and wire system comprising of 3No. timber stakes, 1.75m long x 75-
100mm diam., peeled but untreated with preservative and free of knots likely to
cause weak points. Galvanised wire, 5mm diam. multi-strand attached to each
stake with staples and to form a triangular cage over the rootball.
Stakes shall be at equi-distance spacing around the rootball and driven at an
angle under the rootball leaving at least 500 mm above the level of the pit for
final tensioning. Attach the wire as described, bringing it as tight as possible by
means of fencing pliers or similar. Final tightening of the wire over the top
surface of the rootball mesh is achieved by continuing to drive the stakes until
the wire is as tight as possible.
After final tightening the top of the stakes shall be cut off below finished surface
level.
For trees in excess of 8m high the above specification applies but with the use of
two independent kits per tree i.e. 6No. stakes.
Where ground conditions below the pit prevent the use of driven timber stakes then
one of the following may be employed -
Ground anchorage system such as:
‘Platipus Systems Rootball Fixing Kit’
Supplied by Platipus Anchors Limited, Perrywood Business Park, Honeycrock Lane,
Salfords, Nr Redhill, Surrey RH1 5DZ Tel: 01737 762300
All work to be manufacturers instructions.
or,
Deadman System (Diagram No. 1C) 1 No. underground support system comprising:
50
2No. deadmen located at opposite sides of the rootball. Deadmen shall be timber or
concrete, rectangular in section and of sufficient mass to prevent movement when
buried below the soil. (For example, for a tree 5m tall a timber deadman should
have a section approximately 250mm wide x 100mm thick x 1500 long.)
The deadmen and wire must be fixed prior to backfilling the pit or placing the tree.
5mm diam. multi-strand wire stapled around each deadman shall be tensioned by
turnbuckle or ratchet devices after the tree is in its final position.
4. DRAINAGE / AERATION UNIT –
The drainage / aeration pipe such as Greenleaf ‘Root Rain Urban’ should be
installed after the underground support to prevent damage to the pipe.
The drainage / aeration pipe, 60 mm diameter, shall fully encircle the rootball at
approximately 2/3 rds its depth with a vertical tail reaching to the surface of the
pit. A removable perforated end cap should be used at ground level to prevent
debris blocking the pipe.
For semi – mature trees with a rootball in excess of 1200 mm diameter the pipe
should form a spiral with at least two complete turns encircling the rootball.
5. RAISED EDGE (Diagram No. 5) Where there is the possibility of regular vehicle overrun a raised edge to the tree pit
will be constructed. In a pavement situation there must be a minimum total width of
3m and there shall be a minimum clear path of 1.5m.
construct the raised edge using Marshalls ‘Keykerb’ units (code KL Bullnosed)
or similar to approval, to provide an upstand of 125mm.
colour to be ‘Brindle’ unless otherwise specified.
kerb blocks to be set on a concrete bed 100mm thick and haunched to rear.
The haunching shall be sufficient to hold the blocks firm but shall not extend any
further than 100mm into the pit and shall allow for a full covering of the surface
aggregate.
kerb blocks will be butt jointed with no pointing
6. RESIN-BOUND AGGREGATE PIT SURFACE
Resin-bound surfacing shall be the Greenleaf ‘Arboresin’ system or similar to
approval and laid in accordance with the manufacturers instructions.
51
Aggregate shall be 6-12mm, double washed and dried and a colour to approval
of the Authority.
Lay a sheet of porous geotextile material over the area to be covered with the
aggregate.
Spread loose aggregate over the geotextile mat to a depth of 50mm. (This must
not be resin-bound)
Lay resin-bound aggregate to a depth of 75mm over the entire area to be
surfaced with the exception of a 50mm gap around the tree trunk. This void
shall be filled with loose un-bound aggregate.
The top of the irrigation pipe will finish flush with aggregate surface.
52
3.12 SPECIFICATION – TREES IN PAVING – PLANTED IN A CONTINUOUS SOIL TRENCH AND / OR REINFORCED POROUS CONCRETE SURROUND BS 4043 & BS 4428 apply
Refer to Diagram No. 6 For full details relating to the resin – bound aggregate surface refer to detail
Specification 3.11
1. TRENCH SIZE AND CONSTRUCTION -
Trenches: the minimum size for a continuous soil strip will be 2.5m wide x 1.2m
deep. The length will be as long as possible to maximise the volume. In
situations where there are adjacent services or foundations the sides of the
trench a root barrier will be installed to form an unbroken barrier to one or both
sides of the trench (see para 1.6.1).
In the base of the trench place clean aggregate, 50mm nominal size, to a depth
of 200mm. Cover the stone with a geotextile mat.
If approval is given by City of Newcastle upon Tyne – Engineering Services
dept., lay a 50mm diam. perforated plastic land drain pipe at the base of the
stone layer throughout the complete length of the trench. The pipe is to be
connected, at its lowest point, to an adjacent drainage system in accordance
with details supplied and approved by the City of Newcastle upon Tyne.
Backfill the trench using good quality topsoil with a light texture and conforming
with BS 3882 ‘General Purpose Category’ (see para 1.5.1). Topsoil to be placed
in layers 300mm and settled by light treading between each layer.
In areas where vehicle overrun is likely on a regular basis then a ‘load-bearing
soil’ should be used and installed as paragraph 2.02.
2. PLANTING & UNDERGROUND SUPPORT – refer to Specification 3.11
3 REINFORCED PAVING SURROUND –
An area of porous surface paving shall be laid over the topsoil and shall cover
an area of at least 8 sq. m. and be adjacent to the resin bound aggregate
surface of the planting pit.
The porous paving shall comprise – a Geotextile sheet laid over the topsoil;
150mm ‘no-fines’ concrete reinforced with Tensar Geogrid (Netlon); Geotextile
sheet overlaying the concrete; the specified paving material laid on a sand bed
53
and sand jointing only, no mortar. This surface shall be constructed prior to tree
planting commencing.
4. DRAINAGE / AERATION UNIT – refer to Specification 3.11
54
3.13 SPECIFICATION – TREES IN PAVING – ROOT DIRECTOR / ROOT BARRIER BS 4043 & BS 4428 apply
Refer to Diagram No. 4 For full details relating to the resin – bound aggregate surface refer to detail
Specification 3.11 For full details relating to planting rootballed trees with underground support refer to
Specification 3.6. For full details relating to bare root trees 3.9 or 3.10
1. PIT SIZE AND CONSTRUCTION -
Pits: the minimum size of the tree pit will be 1200 x 1200 x 1100mm deep.
Excavate a planting hole 600 mm wider than the diameter of the rootball. The
depth of the excavated pit will be sufficient to accommodate the rootball and to
obtain the correct planting depth.
Install a layer of clean stone or granular material such as reclaimed broken
bricks to a settled depth of 200mm. Cover with a geotextile sheet to filter fine
particles.
2. INSTALLATION OF ROOT DIRECTOR / ROOT BARRIER
Supply and install a Root Director (product code RD1050) as supplied by
Greenleaf, Haywood Way, Hastings, East Sussex. TN35 4PLInstallation
Installation to be in accordance with the suppliers instructions but the following
points should be noted –
- backfill the pit with topsoil to cover the drainage layer by 320mm depth after
light compaction.
- the lower flange of the Root Director must be level thus ensuring that the top
lip is level and positioned correctly in relation to the finished surface levels.
- backfill the planting pit simultaneously with backfilling the outside with
compacted GSB. The compacted GSB must not be deeper than the depth of
the Root Director.
- topsoil within the Root Director must not overflow the top flange.
55
PART 4
4.00 TREES SUITABLE FOR STREET PLANTING IN NEWCASTLE UPON TYNE
This list is for guidance only and is not intended to be exhaustive.
4.01 Small Trees –height unlikely to exceed 10m within 25 years
Acer campestre ‘Streetwise’ an upright form of Field Maple, good autumn
colour
Malus species – Crab Apple:
Malus hupehensis red fruit
Malus trilobata large flowers, occaisional fruit
Malus tschonoskii excellent upright street tree, good flowers but
rarely fruits
Prunus species – Flowering Cherry:
Prunus ‘Ichiyo’ upright tree, pink flowers, an excellent street tree.
Prunus padus ‘Albertii’
Prunus padus
Prunus ‘Pandoro’
very free flowering, strong upright growth
the native ‘Bird Cherry
upright tree with excellent juvenile and autumn
leaf colour
Prunus sargentii ‘Rancho’
Prunus x schmittii
upright form of the above
pright growth, polished brown bark
Prunus ‘Sunset Boulevard’ upright Cherry, pink flowers and excellent autumn
colour
56
Pyrus – Ornamental Pear :
Pyrus ‘Beech Hill’ upright, narrow, growth, flowers in profusion, very few
fruits
Pyrus ‘Chanticleer’ another excellent tree similar to the above
Sorbus species – Rowan & Whitebeam :
Sorbus aria ‘Majestica’
Sorbus aucuparia ‘Cardinal
Royal’
round-headed tree, large leaves very silver in the
spring, bright red fruit upright form bearing large
quantity of red berries
Sorbus commixta ‘Embley’
Sorbus intermedia
compact growth, excellent autumn colour and yellow
berries
Swedish Whitebeam, tough tree that tolerates
exposed sites, silver foliage in the spring and good
crops of autumn berries
Sorbus x thuringiaca
‘Fastigiata’
formal ‘lollipop’ shape, does not spread wide, good
autumn fruit.
4.02 Medium Trees – height unlikely to exceed 15m within 25 years
B
e
t
u
Betula pendula ‘Tristis’ – reliable form of Silver Birch
Corylus collurna – ‘Turkish Hazel’, upright growth, good autumn colour,
(may eventually get large in good growing
conditions)
Fraxinus angustifolia
‘Raywood’
variety of Ash with fine, light foliage that turns
purple in the autumn
Acer platanoides ‘Columnare’ an upright form of Norway Maple excellent autumn
colour
Alnus cordata – Italian Alder tolerates dryer soils and retains leaves
until mid- winter
57
4.03 Large – height likely to exceed 15m within 25 years, with a spread of 6 m +
Acer platanoides ‘Emerald Queen’ good form of Norway Maple, tolerates some
exposure
Acer platanoides ‘Deborah’ form of Norway Maple, young leaves tinged
purple
Fagus sylvatica Common Beech - ultimately a very large tree
Fagus sylvatica ‘Dawyck’ a very narrow upright form of Beech
Fagus sylvatica ‘Riversii’ a purple-leaved form of Beech makes a bold
landscape statement but should not be over-used
Fraxinus excelsior ‘Westhof’s
Glory’
a good form of Ash, very tough and will survive
most situations
Liquidambar styraciflua Sweet Gum - foliage turns crimson and gold in
the autumn
Liriodendron tulipifera ‘Tulip Tree’ young leaves bright yellow turning
light green very striking appearance
Platanus x hispanica London Plane ultimately a huge tree, but where
space permits the ideal city tree. Very tolerant of
pollution interesting fruit in abundance. Large
leaves are slow to break down and may block
gullies etc.
Quercus palustris Pin Oak bold foliage and scarlet autumn colour
Tilia x euchlora Lime - virtually free of aphids and associated
problems
Tilia tomentosa ‘Brabant’ Lime a dense conical tree excellent for avenues
Ginkgo biloba
Prunus avium ‘Plena’
‘Maidenhair Tree’, narrow when young, broadening
later, good autumn colour
the native Cherry
Quercus robur ‘Fastigiata’
Tilia cordata ‘Green spire’
upright form of the ‘English Oak’
Lime, more free of aphid problems than other
Limes
58
4.04 The following trees are not suitable for planting in a highway situation for the
reasons indicated. However this list is advisory, a tree which is not suitable in a
vehicular area e.g. Horse Chestnuts where ‘Conkers’ attract children, may be
considered for a grass verge set well back from the highway and adjacent property.
Acer
pseudoplatanus –
Sycamore
a large tree that can attract aphids in summer causing a
sticky ‘honey dew’ to drop onto paths, vehicles, seat etc.
However it is also recognised that the same aphid population
is valuable to some species of urban birds as a food source
during the nesting season.
Acer saccharinum an attractive tree but with a weak branch structure that can
be damaged and drop in exposed locations
Aesculus species All the Aesculus (Horse Chestnut), species with the exception
of the variety ‘Baumannii’, produce ‘Conkers’ which attract
children in season with the associated danger from traffic. All
varieties tend to be large and wide-spreading with a very
dense canopy. For these reasons they cannot be
recommended adjacent to highways. However, they make
superb trees where space permits.
Betula pubescens a form of Silver Birch propagated from seed and therefore of
inconsistent form. They also tend to be very shallow rooting
which will cause problems in paved areas, and may suffer
heavy aphid infestation with the resulting problems of
‘honeydew’.
Eucalyptus species liable to become very top heavy and fall in high winds unless
correctly managed at an early age
Malus varieties although suitable Malus are listed in the ‘small trees’ category
above the following varieties include some of those likely to
produce a large amounts of fruit which can cause problems
on pavements or roadways, particularly in wet weather -
Malus floribunda; M. ‘Golden Hornet’; M. ‘John Downie’;
M. ‘Rudolf’
59
Also be aware of the following
Populus and Salix
species
Poplars and Willows have extensive and vigorous roots that
actively seek water and damp ground. They should never be
planted in paved areas adjacent to buildings or where services
(particularly water or drainage) are present.
Robinia species fast growing trees that are not tolerant of exposed conditions
and may drop heavy branches.
Tilia europaea &
T. platyphyllos –
Limes that suffer from heavy infestations of aphids resulting in
‘showers’ of sticky honey dew.
Prunus species and
varieties
the Cherries make superb flowering street trees but often
suffer from a canker disease that is currently prevalent in
parts of the British Isles. If this disease takes hold in
Newcastle Prunus could no longer be recommended for large
scale planting. Additionally, Prunus have a vigorous, far-
searching and shallow root system that will cause damage to
pavings. For this reason it is recommended that a form of root
director be used at the time of planting in locations where
damage to surface paving may cause a problem.
60
Appendix 1
List of Suppliers:
1 Root Barriers and Root Control Systems –
English Woodlands (Burrow Nursery)
Herrings Lane, Cross-in-Hand, Heathfield, East Sussex, TN21 0UG Tel 01435 862992
Green-Tech Ltd Sweethills Park, Nun Monkton, York YO26 8ET Tel. 01423 332100
Greenleaf Horticulture Haywood Way, Hastings, East Sussex. TN35 4PL Hy –Tex (UK) Ltd PO Box 97, Aldington, Ashford, Kent TN25 7EA
Tel. 01233 720097 Peter Scott Tree Care Hamil House, Hamil Road, Burslem,Stoke-on –Trent
ST6 1AQ Tel. 01782 825101 Terram Ltd Mamhilad, Pontypool, Gwent, NE4 0YR
Tel. 01495 767444
2 Tree Guards and Tree Grilles
Broxap Ltd Rowhurst Industrial Estate, Chesterton, Newcastle-under-Lyme, Staffordshire ST5 6BD Tel. 01782 564411
The Great British Bollard Company
PO Box 6, High Flatworth, Tyne Tunnel Trading Estate, North Shields, Tyne & Wear, NE29 7SJ
Ollerton Samlesbury Bottoms, Preston, Lancs PR5 0RN Tel. 01254 852127
3 Porous Surfacing for tree pits
Addagrip Surface Treatments UK Ltd Addagrip House, Bell Lane Industrial Estate, Uckfield, East Sussex TN22 1QL Tel. 01825 761333
SureSet UK Unit 32, Deveril Rd. Trading Estate, Sutton Verney, Warminster, Wiltshire, BA12 7BZ Tel. 01985 841260
4 Below-ground Anchoring Systems
Platipus Anchors Ltd. Kingsfield Business Centre, Philanthropic Road, Redhill, Surrey, RH1 4DP Tel. 01737 762300
61
Bibliography & Literary Citations
1 UK Strategy for Sustainable Development. DoE Consultation Paper, July 2003.
2 Trees Newcastle, A Tree Strategy for Newcastle upon Tyne. April 2002
3 Ryan, HDP (1985) Vegetation’s Impact on Urban Infrastructure. Journal of
Arboriculture 11 (4): 112 – 115
4 Bernatzky, A, (1982) The Contribution of Trees and Green Spaces to a Town
Climate. Energy & Buildings 5 (1): 1-10
5 Edwards, T & Gale, T, (1993) Specification Guide; Trees in Paving. Plant User
13: 2
6 As (5) : Table 1
7 Lindsey, PA & Bassuk, N (1991) Specifying Soil Volumes to Meet the Needs of
Urban Street Trees and Trees in Containers. Journal of Arboriculture 17.6 :141 -
148.
8 Landscape Architecture, January 1991. From the Ground Down pp 66 - 68
Extract from Street Trees Guidance 2006
4.00 TREES SUITABLE FOR STREET PLANTING IN NEWCASTLE UPON
TYNE
This list is for guidance only and is not intended to be exhaustive.
4.01 Small Trees –height unlikely to exceed 10m within 25 years
Acer campestre ‘Streetwise’ Upright form of Field Maple, good autumn colour
Malus species – Crab Apple:
Malus hupehensis Red fruit
Malus trilobata Large flowers, occaisional fruit
Malus tschonoskii Excellent upright street tree, good flowers but rarely fruits
Prunus species – Flowering Cherry:
Prunus ‘Ichiyo’ Upright tree, pink flowers, an excellent street tree. Prunus padus ‘Albertii’ Prunus padus Prunus ‘Pandoro’
Very free flowering, strong upright growth Native ‘Bird Cherry Upright tree with excellent juvenile and autumn leaf colour
Prunus sargentii ‘Rancho’ Prunus x schmittii
Upright form of the above Upright growth, polished brown bark
Prunus ‘Sunset Boulevard’ Upright Cherry, pink flowers and excellent autumn colour
Pyrus – Ornamental Pear :
Pyrus ‘Beech Hill’ Upright, narrow, growth, flowers in profusion, very few fruits
Pyrus ‘Chanticleer’ Another excellent tree similar to the above
Sorbus species – Rowan & Whitebeam :
Sorbus aria ‘Majestica’ Sorbus aucuparia ‘Cardinal Royal’
Round-headed tree, large leaves very silver in the spring, bright red fruit upright form bearing large quantity of red berries
Sorbus commixta ‘Embley’ Sorbus intermedia
Compact growth, excellent autumn colour and yellow berries Swedish Whitebeam, tough tree that tolerates exposed sites, silver foliage in the spring and good crops of autumn berries
Sorbus x thuringiaca ‘Fastigiata’ Formal ‘lollipop’ shape, does not spread wide, good autumn fruit.
4.02 Medium Trees – height unlikely to exceed 15m within 25 years Betula pendula ‘Tristis’ –
reliable form of Silver Birch
Corylus collurna – ‘Turkish Hazel’, upright growth, good autumn colour, (may eventually get large in good growing conditions)
Fraxinus angustifolia ‘Raywood’ Variety of Ash with fine, light foliage that turns purple in the autumn
4.03 Large – height likely to exceed 15m within 25 years, with a spread of 6 m + Acer platanoides ‘Emerald Queen’ Good form of Norway Maple, tolerates some
exposure Acer platanoides ‘Deborah’ Form of Norway Maple, young leaves tinged
purple Fagus sylvatica Common Beech - ultimately a very large tree Fagus sylvatica ‘Dawyck’ Very narrow upright form of Beech Fagus sylvatica ‘Riversii’ Purple-leaved form of Beech makes a bold
landscape statement but should not be over-used
Acer platanoides ‘Columnare’ Upright form of Norway Maple excellent autumn colour
Alnus cordata – Italian Alder tolerates dryer soils and retains leaves until mid- winter
Ginkgo biloba Prunus avium ‘Plena’
‘Maidenhair Tree’, narrow when young, broadening later, good autumn colour Native Cherry
Quercus robur ‘Fastigiata’ Tilia cordata ‘Green spire’
Upright form of the ‘English Oak’ Lime, more free of aphid problems than other Limes
Fraxinus excelsior ‘Westhof’s Glory’
Good form of Ash, very tough and will survive most situations
Liquidambar styraciflua Sweet Gum - foliage turns crimson and gold in the autumn
Liriodendron tulipifera ‘Tulip Tree’ young leaves bright yellow turning light green very striking appearance
Platanus x hispanica London Plane ultimately a huge tree, but where space permits the ideal city tree. Very tolerant of pollution interesting fruit in abundance. Large leaves are slow to break down and may block gullies etc.
Quercus palustris Pin Oak bold foliage and scarlet autumn colour Tilia x euchlora Lime - virtually free of aphids and associated
problems Tilia tomentosa ‘Brabant’ Lime a dense conical tree excellent for avenues
4.04 The following trees are not suitable for planting in a highway situation for the
reasons indicated. However this list is advisory, a tree which is not suitable in a vehicular area (e.g. Horse Chestnuts where ‘conkers’ attract children,) may be considered for a grass verge set well back from the highway and adjacent property.
Acer pseudoplatanus – Sycamore Large tree that can attract aphids in summer
causing a sticky ‘honey dew’ to drop onto paths, vehicles, seat etc. However it is also recognised that the same aphid population is valuable to some species of urban birds as a food source during the nesting season.
Acer saccharinum Attractive tree but with a weak branch structure that can be damaged and drop in exposed locations
Aesculus species All the Aesculus (Horse Chestnut), species with the exception of the variety ‘Baumannii’, produce ‘conkers’ which attract children from mid to late summer with associated danger from traffic. All varieties tend to be large and wide-spreading with a very dense canopy. For these reasons they cannot be recommended adjacent to highways. However, they make superb trees where space permits.
Betula pubescens A form of Silver Birch propagated from seed and therefore of inconsistent form. They also tend to be very shallow rooting which will cause problems in paved areas, and may suffer heavy aphid infestation with the resulting problems of ‘honeydew’.
Eucalyptus species Liable to become very top heavy and fall in high winds unless correctly managed at an early age
Malus varieties Suitable Malus are listed in the ‘small trees’
category above but the following varieties include some of those likely to produce a large amounts of fruit which can cause problems on pavements or roadways, particularly in wet weather - Malus floribunda; M. ‘Golden Hornet’; M. ‘John Downie’; M. ‘Rudolf’
Also be aware of the following
Populus and Salix species Poplars and Willows have extensive and vigorous roots that actively seek water and damp ground. They should never be planted in paved areas adjacent to buildings or where services (particularly water or drainage) are present.
Robinia species Fast growing trees that are not tolerant of exposed conditions and may drop heavy branches.
Tilia europaea & T. platyphyllos –
Limes that suffer from heavy infestations of aphids resulting in ‘showers’ of sticky honey dew.
Prunus species and varieties the Cherries make superb flowering street trees but often suffer from a canker disease that is currently prevalent in parts of the British Isles. If this disease takes hold in Newcastle Prunus could no longer be recommended for large scale planting. Additionally, Prunus have a vigorous, far-searching and shallow root system that will cause damage to pavings. For this reason it is recommended that a form of root director be used at the time of planting in locations where damage to surface paving may cause a problem.