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Wandle Trail, Merton Summary of Ecological Lighting Constraints February 2016

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Wandle Trail, Merton

Summary of Ecological Lighting Constraints

February 2016

Wandle Trail, Merton Summary of Ecological Lighting Constraints February 2016

About Sustrans

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Report prepared by;

Hannah Lewis MCIEEM (Ecologist)

The Walker Building, 58 Oxford Street, Digbeth, Birmingham B5 5NR

Telephone: 0121 633 5501

Report Checked by;

David Watson MCIEEM (Sustrans Greener Greenways Ecologist)

The Walker Building, 58 Oxford Street, Digbeth, Birmingham B5 5NR

Telephone: 0121 633 5501

Wandle Trail, Merton Summary of Ecological Lighting Constraints Report Number: FINAL

Revision Number: 0

Copies of this document may not be current and you should check before further

use.

Purpose of issue: Draft for discussion

Issue date: 26/02/16

Date printed: 26/02/16

Author: Hannah Lewis

Checked by: David Watson

Wandle Trail, Merton Summary of Ecological Lighting Constraints February 2016

Table of contents

1 Introduction .................................................................................................................................. 1

2 Ecological Constraints for Lighting Design ................................................................................... 2

3 Ecological Constraints for Lighting Installation............................................................................. 9

References and Bibliography ............................................................................................................ 13

Appendix 1: ....................................................................................................................................... 14

Appendix 2: ....................................................................................................................................... 15

1 Wandle Trail, Merton Summary of Ecological Lighting Constraints February 2016

1 Introduction

Sustrans are providing advice to London Borough of Merton regarding changes to a lighting scheme

on the Wandle Trail in Merton, London. This route is situated between Trewint Street in

Summerstown and Garfield Road in South Wimbledon (National Grid References TQ2594 7261 and

TQ 2624 7093 respectively). The project involves replacing existing lighting between NGR TQ 2160

7151 and TQ 2649 7108 and introducing new lighting for the remainder of the path.

The entire route is situated within an ecologically valuable corridor of semi-natural habitats. As such

any lighting scheme must be sensitively designed. The long-term impacts of increasing light levels

and the impacts of any construction must both be taken into consideration.

Preliminary Ecological Appraisals, a pre-development lighting assessment and a bat survey have

been conducted at the site by Sustrans (2013) and Richard Graves Associates (2015). Overall, the

detailed lighting design must aim to minimise the impact of the lighting scheme through adherence

to the recommendations in the following documents, extracts of which are provided in the

Appendices of this document;

Richard Graves Associates (August 2015) Updated Ecological Surveys for the Wandle Trail;

and,

Bat Conservation Trust (2014) Artificial Lighting and Wildlife. Interim Guidance:

Recommendations to help minimise the impact artificial lighting.

From these ecological surveys, and an additional walkover survey conducted in February 2016 by

Hannah Lewis MCIEEM (Sustrans), constraint maps have been prepared to inform detailed lighting

design and highlight the location of the most ecological sensitive features along the route.

Information has also been provided in relation to other ecological constraints that may affect the

installation of lighting (e.g. should any work be required in the soft landscaping around the path)

including maps of known locations of legally controlled invasive weeds.

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2 Ecological Constraints for Lighting Design

The entire route is situated within an ecologically valuable corridor of semi-natural habitats. As such

any changes to the lighting scheme must be sensitively designed and must follow the

recommendations of Richard Graves Associates (2015) and best practice guidelines (BCT 2014).

Drawings 2.1 – 2.5 show the features and zones that would be most affected by being lit. These

have been classified as High Risk or Moderate Risk. This is not to say that the remainder of the

habitats are of low value, simply that the risk of significant negative impacts occurring from lighting

in those areas is lower.

It should be noted that any reduction in current use of the river corridor by bats or other wildlife

caused by the existing lighting has not been taken into consideration in these maps. This is because

the existing lighting is to be removed and the new lighting scheme should be designed to allow

maximum future use of the river corridor by wildlife.

High Risk Features and Zones include:

Trees or structures with features that could be used by roosting bats; and,

Areas of the river and bankside habitats that are clearly visible from the path.

Moderate Risk Features and Zones include:

Mature trees that have low/negligible value bat roosting features but that may be valuable in

the future; and,

The river and bankside habitats that are partially screened from the path by vegetation.

The lighting levels of high risk features and zones should not be increased from current light levels.

Should increased lighting levels be required at features with potential to be used by roosting bats,

further surveys will be needed to determine whether a bat roost is present. If so, a Natural England

Development licence may be required.

The moderate risk zones and features should not be directly lit, and lighting kept to the minimum

level needed.

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4 Wandle Trail, Merton Summary of Ecological Lighting Constraints February 2016

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3 Ecological Constraints for Lighting Installation

During the installation of lighting, any work to be undertaken in the soft landscaping along the path

must also be conducted in an ecologically sensitive manner. Should extensive work be required in

semi-natural habitats a detailed ecological survey would be required. For minor work within the

verge of the path, the following ecological constraints have been identified;

Invasive non-native species

Three invasive non-native species listed under Schedule 9 of the Wildlife and Countryside Act have

been identified along the route; giant hogweed Heracleum mantegazzianum, Japanese knotweed

Fallopia japonica and Himalayan balsam Impatiens glandulifera. Any digging or movement of

vehicles that could disturb soil has potential to spread these three species in contravention of

current legislation. Drawings 3.1 and 3.2 show the known locations these three species from

surveys by Sustrans (2013 and 2016) and Richard Graves (2015). It should be noted however, that

these surveys were not all undertaken at appropriate times of year to detect these species and

invasive species control has been undertaken along the route. As such additional plants are likely to

be present that were not recorded during these site visits.

A Method Statement will be required to demonstrate how the spread of these species will be

prevented during the installation of lighting. All personnel working on site must be aware of the

presence and identification of these species and the requirement of the Method Statement.

All staff will also need to be aware of the health and safety implications of working near giant

hogweed and the Method Statement must also include measures to protect staff and users of the

path.

Nesting Birds

Should the clearance of scrub or shrubs be required, this has potential to disturb nesting birds. The

peak breeding season for birds is generally considered to be March to September inclusive but is

weather dependent. Where possible, vegetation clearance in this period should be avoided. If

vegetation clearance in the nesting season is required, it must first be checked for nesting birds by a

suitably experienced ecologist.

Mature Trees

Digging has potential to damage tree roots. It is anticipated that excavations will be limited in extent

and the risk and scale of impacts would be low. Given the maturity and high value of trees along the

route, excavation should follow BS 5837:2012 Trees in relation to design, demolition and

construction – Recommendations

River

Any work near the river must follow best practice guidelines for work around water courses and

pollution prevention to ensure the river is protected throughout the proposed works.

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References and Bibliography

Richard Graves Associates (August 2015) Updated Ecological Surveys for the Wandle Trail

Bat Conservation Trust (2016) Bat Surveys for Professional Ecologists: Best Practice Guidelines

(3rd Edition)

Bat Conservation Trust (2014) Artificial Lighting and Wildlife. Interim Guidance: Recommendations

to help minimise the impact artificial lighting

British Standard 5837:2012 Trees in relation to design, demolition and construction –

Recommendations

Stone, E.L. (2013) Bats and lighting: Overview of Current Evidence and Mitigation. Bats and Lighting

Research Project, University of Bristol

Sustrans (2013) Wandle Trail, Merton: Preliminary Ecological Appraisal

14 Wandle Trail, Merton Summary of Ecological Lighting Constraints February 2016

Appendix 1:

Extract from Richard Graves Associates Update Ecological Survey: Recommendations Relating to Lighting

Lighting during construction and operation is likely to be the most significant potential impact on bat

populations. The compounds locations do not appear to be within the most sensitive areas, however

they should be left unlit at night, or if this is not possible because of security concerns, lighting should

not be directed towards vegetation.

Lighting operating along the path should be avoid as much as possible close to mature trees with

higher bat roost potential. Current evidence on bats and lighting (Stone, 2013) suggests that: narrow

spectrum lights with no ultraviolet content, low pressure sodium and warm white light emitting diodes

(LEDs) and directional down lights illuminating below the horizontal plane are likely to have the

lowest impact. However other measures may be used to minimise impact, including the use of

demarcation lights, such as the Falco Solar Pathfinder http://www.falco.co.uk/products/advanced-

cycle-products/led-mark-solar-lights/ may provide minimum impact ‘uplight’ solutions.

As a general principle lighting should be designed to minimise any illumination of surrounding

vegetation or the watercourse. The impact of lighting may also be reduced by amending the times it is

switched on (particularly during the more active parts of the bat season) and / or operating a sensor

based switching system so that they are only activated when they are needed. The efficacy of this

method would depend on levels of use during the most sensitive times.

The current lighting situation along the route is not ideal and if replaced with a more ‘wildlife friendly’

design could be a significant positive impact along the route. There is probably little that can be done

about incursion of existing lighting from outside of the route but the local planning authority could

ensure that future development proposals consider any lighting impacts.

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Appendix 2:

Extract from Bat Conservation Trust (2014) Artificial Lighting and Wildlife. Interim Guidance: Recommendations to help minimise the impact artificial lighting