Greenhill Farm, Pembrokeshire

Introduction

Project description

The asbestos components of this traditional farm complex were demolished in 2019. The majority of the traditional stone barns with slate roofs were retained, and a bat house, replacement courtyard roof, bat accesses and bat boxes provided as compensation. The licence covered pipistrelles, long-eared bats and lesser horseshoe bats.

Ecologist’s name and contact details

Geoff Moxon (Bioscan UK Ltd)

Client’s name

RWE Generation UK plc

Site postcode

SA71 5TJ

Planning authority

Pembrokeshire County Council

Brief site description

A complex of farm buildings in rural Pembrokeshire, including some traditional stone buildings with slate roofs, as well as some more modern asbestos agricultural sheds (the latter now removed).

Pre-works roost structure

Type of structure

Building

Use

Agricultural Building

Condition

Not In Use

Approx. age

Unknown

Main construction material of walls

Block

Roof design

Flat Roof

Roof material

Other

Internal roof structure

Timber Frame

Lighting present on site and its proximity to the roost

None (nearest lighting at RWE power station 450m to the NE)

Photos or annotated figures of roost structure

Pre-works roost description

Species

Lesser horseshoe bat

Number of bats max count

2

Type of roost

Night Roost

Evidence of bats

Bats Seen in Roost

Roost location

Inside Outbuilding

Aspect of roost

Not Applicable

Height of roost entrance (m)

2.5m

Roost material(s)

• Breezeblock / Concrete

Nearest commuting feature

Treeline

Distance to nearest commuting feature (m)

50m

Nearest artificial light source to roost

Nearest lighting at RWE power station 450m to the NE

Nearest artificial light source to roost commuting route

Nearest lighting at RWE power station 450m to the NE

Photos or annotated figures of roost

Proposed works

Description of works

Removal of small concrete building, as part of wider (deteriorating) asbestos structure, on health and safety grounds.

Type of impact upon the roost

Long-Term Roost Modification and Roost Loss

Proposed mitigations

Type of mitigation

Compensation

Specific technical detail of measure

Bat house, replicating exact opportunities exploited by lesser horseshoe in the roost to be lost.

Relevant annotated figures

Roost location

Bat House

Aspect of roost

Not Applicable

Height of roost entrance (m)

2.5m

Roost material(s)

• Bitumen Felt
• Timber
• Breezeblock / Concrete

Nearest commuting feature

Hedge

Distance to nearest commuting feature (m)

40m

Nearest artificial light source to roost

Nearest lighting at RWE power station 450m to the NE

Nearest artificial light source to roost commuting route

Nearest lighting at RWE power station 450m to the NE

Photos or annotated figures of roost

Type of mitigation

Mitigation

Specific technical detail of measure

A traditional pitched slate roof with exposed ridge beam was installed in the barn to replace the original dilapidated roof. The roof was finished in local slate, beneath which was a traditional bitumen felt underlay. This roof was traditionally constructed using untreated and unfinished timbers, incorporating traditional joints with large gaps to provide roosting opportunities.

Gaps between the wall plate and the roof structure on the eastern and western sides of the barn (in the manner of traditional threshing barns/grain stores) allowed free air flow and ensured stable, but cool, internal temperatures. This gap also enabled continued access to any wall cavities. The improved insulation properties of the new roof were considered likely to create near-optimum summer roosting conditions for long-eared bats.

The BLE roost at the top of the NW internal gable wall was re-created like-for-like by cutting holes in the bitumen felt and inserting spacers for bats to access the slots between the top of the thick stone wall and the roof tiles. A window on the western wall covered by corrugated metal sheeting was re-opened to provide an additional access point.

Roost location

Other

Aspect of roost

W

Height of roost entrance (m)

8m

Roost material(s)

• Bitumen Felt
• Slate Tiles
• Timber Roof Frame
• Stone

Nearest commuting feature

Treeline

Distance to nearest commuting feature (m)

40m

Nearest artificial light source to roost

Nearest lighting at RWE power station 450m to the NE.

Nearest artificial light source to roost commuting route

Nearest lighting at RWE power station 450m to the NE.

Type of mitigation

Compensation

Specific technical detail of measure

Five Schwegler 1FF bat boxes were installed on the walls of nearby farm buildings before the works. These were retained as permanent mitigation measures following completion of the works. All were sited on existing nearby farm buildings at a range of aspects to ensure maximum replication of conditions.

Roost location

Bat Box

Aspect of roost

W

Height of roost entrance (m)

3-4m

Roost material(s)

• Other

Nearest commuting feature

Woodland

Distance to nearest commuting feature (m)

40m

Nearest artificial light source to roost

Nearest lighting at RWE power station 450m to the NE

Nearest artificial light source to roost commuting route

Nearest lighting at RWE power station 450m to the NE

Monitoring data

Length of monitoring proposed

1

Frequency of monitoring

Only 1 visit

Type of monitoring

Roost Inspection

Date and time

1st September 2020 10:00

Evidence recorded

1 lesser horseshoe hanging from ceiling in bat house (and evidence of continued pipistrelle and long-eared bat use of wider complex)

Interventions made

None

Final details

Lessons learned

Replication of existing features used by bats on site was shown to work well in this instance (even though the roost replicated was perhaps not one that would immediately be considered ideal for lesser horseshoe bats).