BS5837 Survey

BS5837:2012 Tree Survey at xxx.

Including Arboricultural Impact Assessment, Tree Constraints Plan & Tree Protection Plan.

Prepared for xxx 10th December, 2014

Revision 1: 22nd December 2014

Dr. R. J. M. Wilson BSc. (Hons), PhD, Prof. Dip. Arb. (RFS) Professional member of the Arboricultural Association

Associate member of the Institute of Chartered Foresters

Director. 07789 696072 / 01438 232334 C Trees Ltd., [email protected] 10 Angotts Mead, Stevenage, Herts., SG1 2NJ.

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Contents: 1.0 Summary

2.0 Background 2.1 Instruction 2.2 Techniques 2.3 Limitations 2.4 Weather conditions 2.5 Access conditions 2.6 Validity 2.7 Background information

3.0 Results 3.1 Situation 3.2 Site plan 3.3 Tree assessment

4.0 Arboricultural Impact Assessment 4.1 Trees to be removed 4.2 Trees to be retained 4.3 Impact of retained trees – Tree Constraints Plan 4.4 Design constraints 4.5 Post-construction mitigation 4.6 Impact on Conservation Area

5.0 Tree Protection 5.1 Tree Protection Plan 5.2 Access Facilitation Pruning

5.3 Tree Protection Barriers 5.4 Ground Protection 5.5 Root Protection 5.6 Hard landscaping in Root Protection Areas

6.0 References

7.0 Appendices

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1.0 Summary • Following an instruction from xxx I have conducted an arboricultural survey according to BS5837:2012 on

the trees in the garden of xxx for the purposes of construction planning. • The site is relatively unexposed in a residential suburban setting on a clay loam soil containing gravels &

sands. The soil is of moderate to high fertility. • The site stands in xxx of the xxx Conservation Area. • Lime tree T1 is a lapsed pollard, several decades past the appropriate time for repeat cutting with an

unbalanced crown, a major included bark union and indications of weakened physiology. Long term retention of T1 is no longer viable; it should be removed and replaced.

• A number of trees are of low quality, contribute little to the overall appearance of the property, have defects that make their long term retention impractical and are to be removed: T3, 7, 9, 11 & 15.

• A number of trees are incompatible with the building design and site layout. Generally, these are of low value, contribute little to the character of the Conservation Area and are to be removed: H1, T17 & T18. Magnolia T19 is also to be removed.

• Foundation design should take into account the potential for heave. • The following trees are to be retained: T2, 4 – 6, 8, 10, 12 – 14, 16 & 20-22. • Tree work should be carried out by competent, trained and insured arboriculturists in accordance with

BS3998:2010. • Retained trees are to be protected by Facilitation Pruning, Tree Protection Barriers and additional Root /

Ground Protection measures as described in BS5837:2012. • Key design constraints:

Foundations: Concrete strip footings of sufficient depth to ensure building stability under varying soil moisture conditions would not present any particular difficulties. Construction with sleeved micro-piles would further protect roots and ensure building stability. If used, piling rig to stand outside RPAs.

Services laid in a single common trench where possible, positioned radially with respect to trees to minimise root damage; drains and soakaways to be positioned outside RPAs.

Driveway encroaches onto RPA of lime tree T20 by 25% and is in excess of the recommended maximum of 20%. The new surface should be of a ‘no-dig’ construction as described in BS5837:2012 Section 7.4 and additional mitigation measures will be needed.

• Post-construction mitigation: Replace lime tree T1 with a single semi-mature standard conforming to BS3936-1:1992. Planting should

take place between April and September and should conform to the general requirements of BS4043:1989.

Monitor lime tree T20 for one full growing cycle. Mitigation measures to be employed as required.

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2.0 Background 2.1 Instruction: • I have been instructed by xxx to conduct an arboricultural survey according to BS5837:2012 on the trees in

the garden of xxx for the purposes of construction planning. • The initial enquiry was received by phone on November 6th, 2014 with supplementary information received

by e-mail on November 7th. An instruction to proceed was received by e-mail on November 13th. Inspection took place on December 1st between 10:00 and 13:00hrs.

• The client requires a Tree Survey, Arboricultural Implications Assessment, Tree Constraints Plan and a Tree Protection Plan, to include CAD drawings.

2.2 Techniques used: • Visual Tree Assessment (VTA; Lonsdale, 1999). • Desk-based enquiries: TPO / CA status, geological survey, mapping.

2.3 Limitations: • The contents are intended for the sole use of the clients and their appointed professional structural engineer

and / or architect. It is also understood that the document will be shared with the Local Planning Authority in order to support a Planning Application. No liability is accepted for its use by any other party to advance an argument or claim (including legal or financial) without prior consent.

• No liability is accepted for defects hidden from view by vegetation or other obstacles to access. • Formal assessment of topography, drainage, service conduits, & soil conditions have not been made and

are beyond the scope of this report. • Specific laboratory investigations of soil properties (plasticity index, moisture content, suction pressure) have

not been made and are beyond the scope of this report • This report considers only the potential for the trees to be affected by the proposed development. No liability

for damage arising from any other source or mechanism is accepted. • This report will be deemed to be invalid if a history of such vegetation related subsidence damage in

surrounding properties is known but has not been made known to the surveyor. • The survey area has been limited to that specified in the instruction. Generally, trees less than 5m tall have

been excluded unless of particular relevance. Other trees may be affected should works or vehicle movements extend outside the area described in which case a further inspection and report will be required.

• Plans have been drawn manually based on architect’s drawings. Whilst every effort has been made to represent site conditions and layout accurately, these plans should not be relied upon for detailed planning, design or setting out. Plans reproduced within this report are for illustrative purposes only. No liability is accepted for inaccuracies arising from the use of these plans.

• It is understood that any risks associated with these limitations are accepted by the clients.

2.4 Weather conditions: Overcast, cold, wind force 3.

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2.5 Access conditions: Access was unhindered.

2.6 Validity: Plants are biological organisms and change with time. Assessment health and condition remains valid for six months from the date of inspection, or until a major storm is experienced, after which time a new inspection is required. All other aspects of this report remain valid for two years from date.

2.7 Background information: The property lies within the xxx Conservation Area: xxx. There are no Tree Preservation Orders in force at the site (xxx District Council, website accessed at 13:20 on 10/12/2014).

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3.0 Results:

3.1 Situation:

• The property occupies a level site in a residential suburban area at an elevation of approximately 110-115m near the centre of xxx (Ordnance Survey Get-a-Map, 2014).

• Locally, ground undulates to create a series of low rises on which the various housing developments of xxx stand. Ground slopes gently into the valley of the River xxx to the reaching approximately 80m elevation 1.5km away to the southwest. This is a relatively unexposed location.

• Surface deposits are sands and gravels of the Kesgrave Catchment Subgroup. The underlying bedrocks are chalks of the Seaford and Lewes Nodular Chalk Formations (BGS, 2014). Borehole xxx drilled approx. 500m away to the south in xxx Road reveals the presence of a shallow (0.25m) topsoil over a 2m deep layer of silty clay containing gravel and sand with gravel beneath.

• Soil type is described as a slightly acid clay loam with impeded drainage of moderate to high fertility (LandIS, 2014).

• It is proposed to build a detached house with separate garage of brick and tile construction with access from xxx to the south of the existing building.

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3.2 Site plan:

Tree survey plan at xxx. Green: Category A trees; Blue – Category B trees; Red – Category C trees; Grey – Category U trees. Labels show tree number, retention category, species and height in metres.

3.3 Tree Assessment:

T H D Clr Age P Cond S Cond Rec ERC CatN 5E 5S 10eW 7N 4E 3S 5eW 4N 0E 3S 6W 3N 3E 4S 4W 4NE 5eS 4W 5eN 3E 5SW 5N 3E 2SW 3N 3E 3S 2W 3N 3E 2S 0W 2N 1E 2S 1W 25 110

Fell -9 Cultivated apple 4 239

Prune crown 20+

M

M Fair Good2

-

10+

7 Cultivated pear 8 210 3 Good Poor

2

2 OM Poor Poor

Hollow stem - Fell

FairRemove climber, crown lift to 3mM Good

2 M Fair Fair Thin crown, shorten leaders 20+

10 Prunus sp.

2

M

Thin crown 20+

Good Good None 40+2

6 Cultivated pear 12355, 265

5 European Lime 17 750e

316, 255, 180

341

1 European Lime 27.5 1002 OM Poor

Remedial crown works required severe; tree likely to become moribnd. Fell 10+

2 Mitchell's Whitebeam 8 2 M

4

Good Good None 40+172 B2

U

M

8 Cultivated apple 6 198

3 Lawson's Cypress 'Fletcheri' 8 Fair Poor Fell -

M

0

Good Good4 Cultivated apple 8

Poor

B2

B2

B1

B2

C2

U

B2

U

SpreadSpecies

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T H D Clr Age P Cond S Cond Rec ERC CatN 0E 1S 3W 3N 1E 2S 3W 2N 3E 3S 3WN 4E 4S 4W 3N 1E 1S 1W 1N 0.5E 0.5S 0.5W 0.5N 2E 2S 2W 2N 2E 3SW 3N 4E 3S 3W 4N 6E 6S 5W 6N 1E 2S 3W 4N 3E 3S 1W 4N 3E 3S 3W 2

20 European Lime 16 M Good

22 Holly 8 M

B2

Good Good21 Yew 6

20+ B2

FairH1 Lawson's cypress & yew hedge 8 - 9 M GoodRemove suppressed and leaning stems 20+ B2

17 Holly 6

16 Lawson's Cypress 'Elwoodii' 6 M Good Good

None 20+ B2

18 Mitchells Whitebeam 7 M Good

M

Good

3 None 20+13 Silver Birch 12 M Good Good

20+ B213 M Good

240 B2

15 Western Red Cedar 5 Threatens wall - fellM

Fair Crown lift to balance crown14 European Larch

U

12 Hornbeam 5 Y Good Good None 40+ C295 1.5

Fell -O/M Dead

Species

11 Ornamental Cherry 5 275 Poor

None 40+

None

Good

155

242

620100, 100, 100,

120, 70

Remove climber, crown lift to 3m

Good Good

300e

123, 153, 160

Spread

3

210e

-

252 2

0

0

Good

Good

Good - U

20+ B2

20+ B2

Good

M

FairReduce crown by 30% & away from overhead wire 40+

19 Magnolia 6 None 20+

B2M

B2

0

Fair None

2

2

1.5

4

0

0

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Key: T: Tree reference number H: Height in metres. D: Trunk diameter at 1.5m above ground in mm. (Or diameter derivative where tree multi-stemmed). Spread: Crown spread at four cardinal compass points in metres. Clr: Crown clearance above ground in metres. Age: M – Mature, EM – Early mature. P Cond: Physiological condition. S Cond: Structural condition. ERC: Estimated remaining contribution in years. Cat: BS5837:2012 Retention Category

4.0 Arboricultural Impact Assessment:

Assessment based on Proposed Site Plan (file received from xxx by e-mail 11/12/2014) which has been overlaid on the Tree Survey Plan as follows:

Tree survey plan with proposed buildings at xxx. Green: Category A trees; Blue – Category B trees; Red – Category C trees; Grey – Category U trees. Labels show tree number, retention category, species and height in metres. Proposed buildings are shown in light blue.

4.1: Trees to be removed. • Lime tree T1 is a lapsed pollard, several decades past the appropriate time for repeat cutting. As a result

the crown is significantly unbalanced towards the south, with 20m of post-pollard regrowth supported on weak attachments and affected by a major included bark union. Severe cutting would be required to remedy this situation with the likely result that the tree would become moribund. Pathogenic fungi could be expected to become established further weakening its health and leading to wood decay. Combined with the resident’s report of late leaf-flushing (implying compromised root function) the likelihood of tree death following cutting is high. Therefore long term retention of T1 is no longer viable and it should be removed.

• The following trees are of low quality, contribute little to the overall appearance of the property and have defects that make their long term retention impractical. These trees are shown in red on the plan and should be removed: T3, 7, 9, 11 & 15.

• Retention of the following trees is considered incompatible with the building proposal: H1, T17 & T18. These trees contribute little to the visual amenity of the area.

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• Magnolia T19 is as yet small in size and better described as a shrub. It is proposed to remove this plant and replace with an alternative species.

• Due to the large amount of proposed vegetation removal on a site with a clay soil, foundation design should take into account the possibility of soil movement caused by heave. Formal assessment of the likelihood, magnitude and duration of heave effects is beyond the scope of this report.

• Trees are to be removed by competent, trained and insured arboriculturists according to BS3998:2010. Stumps may be carefully ground out to avoid damage to the roots of nearby retained trees.

4.2: Trees to be retained. • The following trees are to be retained: T2, 4 – 6, 8, 10, 12 – 14, 16 & 20-22.

Plan showing retained trees and proposed buildings at xxx. Green: Category A trees; Blue – Category B trees; Red – Category C trees; Grey – Category U trees. Labels show tree number, retention category, species and height in metres. Proposed buildings are shown in light blue.

• Access facilitation pruning of trees T19 - 22 will be required.

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4.3: Impact of retained trees - Tree Constraints Plan

Root protection areas (black); Crown spreads (green, blue and red crosses); Shade arcs (magenta) Dashed lines represent estimated dimensions; for clarity G2 has been omitted. Shade arcs and RPAs are shown for the most relevant trees only.

4.4: Design constraints. 1. Foundations: Concrete strip footings of sufficient depth to ensure building stability under varying soil

moisture conditions would not present any particular difficulties. Construction with sleeved micro-piles would further protect roots and ensure building stability. If used, piling rig to stand outside RPAs.

2. Services laid in a single common trench where possible, positioned radially with respect to trees to minimise root damage; soakaways etc. to be positioned outside RPAs.

3. Vehicle transits over unprotected RPAs not permitted. Load-spreading boards suitable for the loads expected are to be used.

4. Driveway encroaches onto RPA of lime tree T20 by 25% and is in excess of the recommended maximum of 20%. The new surface should be of a ‘no-dig’ construction as described in BS5837:2012 Section 7.4 and additional mitigation measures will be needed.

5. Tree protection barriers and ground protection to be used to protect RPAs as per BS5837:2012. 6. Gutters may benefit from leaf guards.

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4.5: Post-construction mitigation. • Trees have been identified for removal based on poor form, safety, health and future prognosis. Most trees

are of low amenity value, of non-native species and of little relevance to preservation of the character of the Conservation Area. Replacement of these trees is not considered appropriate.

• Loss of Lime tree T1 is regrettable but is now unavoidable, irrespective of the current development proposal. Replacement with one 14-16cm girth semi-mature container-grown plant conforming to BS3936-1:1992 should be considered. Planting should take place between April and September and should conform to the general requirements of BS4043:1989. Plant should be sited in a purpose-made planting pit back-filled with a 50:50 mixture of top-soil and compost, supplemented with mycorrhizae spores, fitted with an irrigation hose and covered with a 30mm depth of composted woodchip mulch. Plant should be staked and tied with two 50mm diameter pressure-treated stakes.

• Lime tree T20 will be monitored every three months for one full annual cycle. The appearance of symptoms consistent with root-related physiological stress will trigger the use of site remediation strategies which could include (but are not limited to): compressed gas soil decompaction, installation of an irrigation system, soil fertilisation, application of mulch.

4.6: Impact on Conservation Area. • The Conservation Area Character Appraisal produced by the xxx District Council (Draft) makes reference

to the contribution provided by mature trees. • xxx Road was developed in the xxx and it seems reasonable to suggest that Lime T1 dates from around

this period. T20 appears to be younger. • T1 may therefore be around xxx years old. While many limes in open country or parkland can reach greater

ages, the longevity of an urban tree can be expected to be shortened by pollution, hard surfaces and construction pressures.

• A hard-surfaced driveway leading to the rear of xxx passes by the tree immediately to the south. The driveway appears to be of modern construction and appears to have involved some excavation. The roots of T1 are likely to have been compromised, resulting in the late leaf flushing.

• Given the poor structural condition (see above) and the compromised physiological function, T1 can be considered to be nearing the end of its life. The character of the Conservation Area can therefore best be preserved by replacement with another lime at an alternative location.

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5.0 Tree Protection 5.1 Tree Protection Plan.

Yellow line – course of tree protection barrier. Magenta line – parking area to be of ‘no-dig’ construction. Areas bounded by tree protection barriers to be Construction Exclusion Zones.

5.2: Access Facilitation Pruning

• Access facilitation pruning of trees T19, 21 & 22 will be required to reduce the crown spread by at least 1.5m to the west and north over the proposed new driveway.

• T20 should be crown lifted to provide 5m clearance over the ground.

• Tree work should be carried out by competent, trained and insured arboriculturists in accordance with BS3998:2010.

5.3: Tree Protection Barriers • Protection barriers MUST be erected BEFORE any other work commences on site. • Barriers are to be situated along lines shown on the attached Tree Protection Plan and installed under the

supervision of the project arboriculturist. This allows for a 1.5m working space between the barrier and the outer wall of the building.

• Once installed, the barriers MUST NOT be moved. • Since the barriers extend well inside the RPA and there is a risk of root damage from the default standard

of fence construction, the barriers should be constructed according to BS5837:2012, as illustrated in Appendix 2 and as described in Clause 6.2.2.3 as follows:

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‘…2m tall welded mesh panels on rubber or concrete feet…The fence panels should be joined together using a minimum of two anti-tamper couplers, installed so that they can only be removed from inside the fence. The distance between fence couplers should be at least 1m and should be uniform throughout the fence. The panels should be supported on the inner side by stabiliser struts… the stabiliser struts should be mounted on block trays.’

• All-weather notices should be attached to the barrier with words such as ‘CONSTRUCTION EXCLUSION ZONE – NO ACCESS’. • Barriers are to remain in place along this line for the duration of the construction phase.

5.4: Ground Protection • The ground area enclosed by the Tree Protection Barrier is to be regarded as a Construction Exclusion

Zone (CEZ), in other words, it is a NO-GO zone. • Since new planting can be expected adjacent to the drive, in order to protect the ground the CEZ includes

the area currently occupied by T19, even though this tree is not to be retained. • Construction personnel, tools, machinery, materials or other items MUST NOT enter the CEZ for ANY

reason.

5.5: Root Protection • To avoid damage to roots, existing ground levels should be retained within the RPA. • Intrusion into the soil within the RPA, other than for piling, is generally not acceptable. • Trench excavation within the RPA may proceed in a manner arranged radially with respect to retained trees

and by the careful use of hand-held tools. • Exposed roots should be immediately wrapped or covered; wrappings should be removed immediately prior

to backfilling. • Roots less than 25mm diameter may be pruned back, making a clean cut with a suitable sharp tool except

where they occur in clumps. Roots in clumps or over 25mm diameter may only be severed after consultation with the project arboriculturist.

• Prior to backfilling, retained roots should be surrounded with topsoil or uncompacted sharp sand (not builder’s sand because of the high salt content) free from contaminants.

5.6: Hard landscaping in root protection areas • Driveway encroaches onto RPA of T20 by 25% and is in excess of the recommended maximum of 20%. • Tilia sp. roots tolerate construction pressures moderately well (Matheny & Clarke, 1998) but have poor salt

tolerance. The nearby lime T1 may have been affected by the adjacent driveway. • This level of encroachment should be tolerable provided the new surface is designed to adequately

withstand the loads and wear associated with the construction and post-construction phases, and to drain run-off into purpose-made drains (not soakaways).

• The new surface should be of a ‘no-dig’ construction as described in BS5837:2012 Section 7.4. • Footings to be of crushed stone laid into a three-dimensional cellular confinement matrix over a geotextile

membrane, covered with compacted sand above another geotextile layer, and topped with permeable brick paviors or other permeable surface.

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• Turf may be removed using hand-held tools to a depth of no more than 50mm. • Other skimming or regrading is not to be carried out. • Hard surfacing should be set-back from trees and root buttressing by at least 500mm. • Edge supports that do not require excavation should be used e.g. above-ground board-and-pegs. • Soil should be decompacted prior to surface installation in order to offset the large degree of RPA

encroachment.

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6.0 References

British Geological Survey (2014). http://mapapps.bgs.ac.uk/geologyofbritain/home.html. BGS, Keyworth, Nottingham.

British Standards Institute (1989). BS4043:1989 – Transplanting root-balled trees. BSI Publications, London.

British Standards Institute (1992). BS3936-1:1992 – Nursery stock – specifications for trees and shrubs. BSI Publications, London.

British Standards Institute (2005). BS5837:2012 – Trees in Relation to Construction. BSI Publications, London.

British Standards Institute (2010). BS3998:2010 – Standards for Tree Work. BSI Publications, London.

LandIS (Land information system; Soilscape viewer). Cranfield University. http://www.landis.org.uk/soilscapes2/

Lonsdale, D. (1999). Principles of Tree Hazard Assessment and Management. The Stationery Office, London.

Matheny, N. & Clark, J.R. (1998). Trees and Development. International Society of Arboriculture, Champaign, Illinois, USA.

NHBC Chapter 4.2 (2007). National House Building Council, Amersham Bucks.

Ordnance Survey (2014). Get-a-map service at https://www.ordnancesurvey.co.uk/shop/os-getamap.html . Ordnance Survey, Southampton.

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7.0 Appendices

Appendix 1 - Tree Protection Barrier construction