Bat Group response to revised proposals for Westdown Quarry – 1Aug22

The Bat Group were asked by Colin Arnold, Service Manager, Planning and Development SCC to comment on these revised planning applications regarding Hanson’s Westdown Quarry:

These comments are published on our website:

They should be read alongside our previous comments, which also form part of this 1/8/22 response:


Our comments cover six areas. Full details are below:

  1. Greater horseshoe bats (GHB) – Further work needs to be undertaken to understand the use of the site by GHB, the impacts on their nearby roosts, and the wider Mells GHB colony.
  2. Mitigation bat houses – We welcome the details of the bat house proposed for lesser horseshoe bats, however, due to sub-optimal siting, we recommend a second LHS house is required. In addition, a third bat house designed for GHB should be created on Hanson land to the north, to compensate for the disturbance to the Asham conveyor tunnel roost.
  3. Mitigation “cave” roosts – Again we welcome their inclusion, however, we suggest several structures and entrances be included at several heights within the Asham void infill.
  4. Quarry face bat roost loss – We welcome acceptance that this is a process requiring licensing. And suggest it is started as soon as possible.
  5. Corrections to Woods reports. – There are statements in reports which need amendment.
  6. SBG response clarifications – Statements made regarding the bat group, and conflict of interests

1. Greater Horseshoe Bats (GHB)

Radio Tracking

We repeat our comments that we believe insufficient work has been done regarding GHB.

The radio tracking of one pregnant greater horseshoe (GHB) bat is not considered adequate to establish the foraging/commuting/social functions of a site, particularly in relation to the impacts on the Mells Valley SAC and noting Bat Conservation Trust Good Practice Guidelines (Collins 2016). The radio tagging of a second GHB, should not be discussed, or mentioned further, as it was immediately lost, and its radio signal was never tracked.

We note the suggestion from Woods that lesser horseshoe (LHB) can be used as an “umbrella species”, however bearing in mind the importance of the Mells Valley GHB colony, and the changes it is currently undergoing, we refute this.

As background, the original GHB roost at Wadbury Ironworks is currently undergoing large restoration. Surveys by Somerset Bat Group in spring 2022 revealed a slight decrease in the number of GHB in the nearby Wadbury House Tunnels, but a large significant increase in the number of GHB in the Wadbury bat house on the opposite side of the valley. No direct conclusions can be made regarding the Ironwork renovations and the unusual change in GHB numbers. However, we can say that significant changes to the movement of the Mells Valley GHB colony are currently ongoing.

Therefore establishing the GHB’s current use of Hanson’s land, including the GHB roost that is a satellite roost for the Wadbury colony is critical, before any decisions are made.

  • Recommendation 1– Further successful radio tracking of at least 10 GBH be undertaken. With focus on capture on the Fordbury Water corridor and at the Asham conveyor tunnel roost.
  • Recommendation 2 – A HEP based on GHB be submitted

Asham conveyor tunnel roost

This is a historic GHB roost, on Hanson’s land, within 70m of the site, it is correctly identified as a roost of “medium importance”. We note that three external surveys were carried out on three occasions: dawn 16/7/20, dusks 4/8/20 & 26/8/20. However, we know of no recent data collected by Hanson’s on its use outside these times, or the use as a hibernation roost.

As background, the conveyor tunnel was extensively changed in 2019, with the removal of the bund from the entrance, grilling, and installation of internal baffles. Therefore due to the extensive changes, all the historic data pre-June 2019, used in the reports is now invalid.

The only valid hibernation data we now know of is from a Somerset bat group internal roost survey in early Jan 2020, where hibernating horseshoe bats were found.

At a meeting with Hanson’s in Jan 2020 processes and remedial works to allow ongoing safe access by consultants to monitor the tunnel roost were agreed upon and documented to Hanson’s by SBG.

To the best of our knowledge, this work has not been carried out by Hanson’s

  • Recommendation 3 – Required remedial works to the conveyor tunnel are carried out by Hanson’s
  • Recommendation 4 – Hanson’s appoint licenced bat consultants to monitor both hibernation and summer bat use of the conveyor tunnel. And to comply with the requirements of the 2019 Natural England Licence application (reference: 2019-40428-SCI-SCI)
  • Recommendation 5 – As part of this planning approval, obligations are placed on Hanson to continue to have the conveyor tunnel professionally monitored for the working life of the quarry, and experiments are undertaken to optimise the potential roost (use of the baffles and other potential additional internal structures)

2. Mitigation bat house(s)

Lesser horsehoe bats (LHB)

We welcome the details of the construction of the proposed LHB mitigation bat house. We note the proposed siting of the LHB bat house is to the northeast of the site in the offsite mitigation area. While potentially a useful “quieter” location, it is not on the main flight path from the large maternity roost in Westdown Barn. The Bat Baseline Figures 3.14 shows approx three-quarters of the LHB left Westdown Farm in an almost due west direction (70 of 94)

  • Recommendation 6 – A second LHB mitigation house is built due west of Westdown Farm before any works are commenced. Granted this may be a nosier location over the years, but will allow a gradually transitioning to the quieter northeast LHB mitigation house if so.

Greater horseshoe bats (GHB)

We agree with the statement in the ES that “11.21.17 Roosting bats can be disturbed by noise and vibration.” The conveyor tunnel roost is only 70 m from the site and will be subject to traffic, and also blasting noise. We do not agree that “any effects would be of a very low magnitude”.

We note Hanson’s own land to the north of the site on the Fordbury water corridor, and believe this would provide a good site for GHB, accessible on their commute from the Wadbury colony.

  • Recommendation 7 – A third bat mitigation house specifically for GHB is built to the north, on the Fordbury water corridor.

All mitigation bat houses

  • Recommendation 8 – As part of this planning approval, obligations are placed on Hanson to continue to have all the mitigation bat houses professionally monitored for bats for the working life of the quarry.

3. Mitigation Cave roosts.

We welcome the acceptance of our idea of buried pipes to be inserted into the infill of the Asham void to provide “cave-like” structures for bat hibernacula, however, we would like to see more details of these proposals.

We suggest a minimum of, 10 “cave entrances” to lead to at least 5 “chambers”, with entrances at various heights and directions.

  • Recommendation 9 – Plans for “cave-like” structures to be supplied by Hanson’s before planning is granted
  • Recommendation 10 – As part of this planning approval, obligations are placed on Hanson to continue to have the “cave-like” structures professionally monitored for the working life of the quarry

4. Quarry face bat roost loss

We welcome the statement in 2.8.27 “It is acknowledged that further bat survey work and additional detail with regards to mitigation, compensation (and monitoring) for potential roost losses arising from works affecting quarry faces, and trees would be required prior to works commencing; this would be delivered in liaison with Natural England via the licensing process.”

This is likely to be a lengthy process, hence to avoid delay, we suggest these discussions with NE are started immediately, to allow agreed surveys to be carried out ASAP. It would seem that thermal imaging, would be the most suitable survey technique bearing in mind the large areas to be covered.

5. Corrections to Woods reports

Quarry face roosts

In Woods response to SES regarding quarry face roosts, they state that “It is a valid and reasonable assumption that any roost of high conservation significance would have been identified through radio-tracking”.

This would only be valid if a significant percentage of the bats using the site had been radio-tracked (10%+). However, as only 8 crevice dwelling bats were successfully radio-tracked, “it is a valid and reasonable assumption that any roosts of high conservation significance would not have been identified through the very limited radio-tracking”

It is worth noting that one of the 8 crevice dwelling bats, a common pipistrelle, was successfully radio-tracked “to an approximate roost location in a cliff face in Asham Quarry”

Greater horseshoe bat roosts

In the “HEP 2.8.6” it states, “There are no greater horseshoe bat roosts within close proximity to the Site, although the closest is within 4 km.”

This is not true, there are GHB roosts with 1km as listed below, and several others within 4km

  • There is a GHB roost in Asham conveyor tunnel within 70m of the site. This is mentioned and recorded several times in this application.
  • Dead Woman’s Bottom Culvert – 1GHB recorded (EN403 – Billington)
  • Chantry Grotto – GHB and LHB recorded (EN403 – Billington)

Recommendation: The HEP be reevaluated with the corrected data

6. SBG response clarifications

Incorrect collaboration claims

At several points in the reports, it mentions designs or proposals will be worked on in the future with the Somerset bat group. This is not true and has not been agreed with the Somerset bat group.

The bat group has a policy of “doing no work that could or should be done by a professional consultancy”. We have informed Hanson’s via email about this.

The bat group request that all such statements regarding future collaboration be removed from the documents.

Conflict of interests

SBG committee member Adel Avery has declared a conflict of interests regarding these proposals and hence has taken no part bat group discussions or responses regarding these applications.

Contacting Somerset Bat Group

If anyone wants to contact the Somerset Bat group regarding these proposals or this site, then the only email address to use is