Galedffrwd Hydro

Biodiversity enhancement

plan

Dr. Rod Gritten PhD PGCE Cbiol MRSB

(Gritten Ecology)

With contributions from Egni Mynydd:

Jenny Wong, Bryan Dickinson & Bryn Rhys Harris

28th June 2019

1. Introduction The proposal (Application Number: C18/0657/16/CC) to construct a run of the river HEP scheme on the Afon Galedffrwd, Mynydd Llandegai, received consent from Gwynedd Council Planning Department on 7/11/2018 with a number of Planning Conditions. Condition 8 states “Prior to any works commencing on the development hereby permitted a biodiversity enhancement plan shall first be submitted to and approved by the Local Planning Authority”. This document lays out a biodiversity enhancement plan prepared by Egni Mynydd based on all ecological reports prepared for the hydro by Gritten Ecology, Cambrian Ecology, Sam Dyer Ecology, G.L. Jones and Mynydd Timber Services. Given that the developer, Egni Mynydd, owns no land, any proposed enhancements requires consent to be provided. Landowners and neighbours of the scheme were approached to determine whether they would welcome biodiversity enhancement of their property and the form that this might take. This plan is based on agreements made by Egni Mynydd with Coetir Mynydd, Bradite Paint Works, Penrhyn Estate and their tenants, and managers of the property at Yr Ocar. Documents consulted: Dyer, Sam (2017) Bat assessment for proposed Galedffrwd hydropower scheme. Mynydd Llandegai Gritten R. (2016) Coetir Mynydd HEP – Ecological surveys. Gritten Ecology report accompanying

Planning consent. Gritten R. (2019) Galedffrwd HEP - Biodiversity enhancement plan. Gritten Ecology report to Egni

Mynydd. Hall, Chris (2019) Otter survey for proposed Galedffrwd hydropower scheme, Mynydd Llandegai Jones, G.L., Allen, C.J. & Sharpe, N.R. (2017) Nant Galedffrwd Valley Breeding bird survey report. Mynydd Timber Services Ltd (2017) Pre-development arboricultural report (version2) for Coetir

Mynydd (Galedffrwd hydro-electric generation proposal)

1.1. Egni Mynydd

Egni Mynydd is a Community Benefit Society which is developing the Galedffrwd hydro for the benefit of the community of Mynydd Llandegai. The Objects of the Society are: “.. to carry on any business for the benefit of the community by developing and operating a renewable energy project, or projects, plus other community benefit projects.” Along with a provision for profits to be made available for social or community purposes, Egni Mynydd’s long-standing intention is to make payments to Coetir Mynydd for use in accordance with its charitable objectives. Coetir Mynydd’s charitable objects include:

- Conserving for public benefit woodland and other conservation and amenity land in the

vicinity of Mynydd Llandegai - Promoting the enhancement, management and safety of woodland and common land in the

community of Mynydd Llandegai - Advancing public education in woodland, wildlife, the environment, the countryside, local

history and heritage.

It should therefore be appreciated from the outset that the entire hydro project is effectively

concerned with biodiversity enhancement as a significant proportion of the profits are intended to

be spent on long-term biodiversity improvement projects in the local area.

The Galedffrwd scheme

The Galedffrwd hydro scheme follows the route of a pre-existing Victorian pipeline that originally fed

water via numerous small reservoirs (now mostly destroyed) to waterwheels at Penrhyn quarry’s

Felin Fawr slate works at Coed y Parc. In the proposed scheme, a proportion of water from a small

intake near Pont Galedffrwd / Amana will be carried via a pipeline to a turbine house close to Felin

Fawr before being discharged back into the river. The pipeline has been designed to minimise its

impact by following the line of the original scheme which was dismantled in the 1970’s. The pipeline

will be laid over ground in the western section of the valley, then buried or semi-submerged further

down depending on the site conditions and habitat it passes through. The route passes over several

land ownerships, shown in Maps 1 & 2.

Map 1: Most of the western half of the penstock and intake runs through land owned by the

Penrhyn Estate and has tenants at Amana

Map 2: The eastern half of the penstock, turbine house and outfall runs through several

ownerships. Land owned by Coetir Mynydd is marked in brown.

2. Minimising biodiversity impacts

2.1. Mitigation

Trees: Gwynedd CC response to the planning application states: “..To compensate for impact to

trees, a tree planting scheme and woodland expansion plan must be provided” It is unavoidable that

some trees will need to be either removed or pruned to enable construction but Coetir Mynydd has

worked closely on the design to minimise the impact on trees throughout the project area. An

arboricultural method statement has been produced and the planning authority has instructed that

its recommendations be followed prior and during construction. Recommendation include

supervision of works by a qualified arboriculturalist and ecologist, protection of trees, tree roots and

ground conditions. Tree protection barriers, retention of arisings on site and the timing and order of

operations.

Native provenance trees (possibly grown from seed collected on site) will be planted where

connectivity is likely to be lost. Parc yr Ocar woodland currently has a very healthy understorey of

trees and a notably high level of natural regeneration, so additional planting on this site may not be

appropriate throughout, however, several areas including close to the turbine house, in the western

section of the pipeline route and also adjacent land have been identified where additional trees will

be established.

Otters: it has been recommended that: “…Where the potential loss of, damage to or disturbance of

resting sites…is unavoidable, … a safe haven for otters be established prior to works commencing to

provide a safe alternative refuge for otters, that also has the potential to provide the same function

as the sites lost, and as a positive conservation gain, to be a potential breeding location”. Egni

Mynydd has decided that an otter holt will be installed (supervised by a qualified ecologist) in a

suitable area even if disturbance is not established beforehand.

Bats: a bat survey by a qualified bat ecologist was carried out and all the recommendations for

mitigation will be followed. These include all reasonable avoidance measures, timing and order of

works, erection of appropriate bat boxes, reporting and monitoring. During the bat survey a single

Natterer’s bat was observed roosting within a shallow rot hole. It has been recommended that

mitigation in the form of bat boxes will be required to off set the impact of the loss of the roost. The

Natterer’s bat will be accommodated within five Schwegler bat boxes hung within the woodland on

existing mature trees. Prior to commencement of felling mitigation from the bat boxes will be

erected as dictated by licensed bat worker.

Additionally: “The known roost of Lesser Horseshoe bats is located 100m from the outfall is not

expected to be impacted..but the roost access.. must be safeguarded.” “With careful selective felling

and pollarding wherever possible instead of felling, the construction of the turbine house should not

impact on the culvert exit.. This will safeguard connectivity with the surrounding habitats…Should

additional felling be required that may impede the connectivity with the CSZ and woodland, then

additional planting may be required in the area.

Birds: A bird survey has been carried out and recommendations (including the timing and order of

ground clearance and constructions works, retention of mature trees) to avoid negative impacts on

nesting birds will be followed. If it is necessary to remove trees with potential for hole nesting birds,

then nest boxes should be provided.” Several nest boxes are already in place on site and the

requirement for more will be assessed by a qualified ecologist as tree works are finalised.

Fish: Following recommendations, at the intake, a pool pass is to be formed with mortared stone

forming a natural functioning fish passage. This will consist of a series of pools, each 300mm above

the next. To protect fish traveling downstream, a plunge pool below the intake will be created using

appropriately sized and positioned boulders.

Ground vegetation: No specific mitigations have been suggested but Coetir Mynydd is keen for long-

term impacts to be minimised. For much of the route the pipe will be laid over ground. At Yr Ocar it

will be buried, then semi-submerged along an existing track before crossing the river. From the river

crossing it will be laid into an existing trench (a remnant of the previous pipe route utilised up to the

1970’s). Here, as much ground vegetation as possible will be rescued and replaced once work in that

area is complete. The pipeline through the pastures in the lower section will be completely buried.

Impacts on the sward will be reduced by removing turfs and topsoil separately, excavating subsoil

which is then stored separately and the whole returned in the appropriate sequence. Vegetation

restoration will occur in one growing season. Any bare ground in this area can be re-seeded with

appropriate species following discussions with the landowner and a qualified ecological advisor.

3. Biodiversity enhancement The biodiversity recommendations provided by Gwynedd County Council (2nd October 208) in their

response to the planning application, states:

“For the mitigation and enhancement of biodiversity: A biodiversity mitigation and enhancement

plan must be provided that includes tree planting, woodland creation, otter holt creation, bird

nesting sites. It should also include the control of invasive plant species”

3.1. Turbine house

Two Schwegler Woodcrete bat boxes will be incorporated into the fabric of the Turbine House

building. Bat surveys have shown that several species that use this sort of roost box are present in

the woodland.

3.2. Coetir Mynydd property

3.2.1 Woodland management:

There are a number of Sitka Spruce (Picea sitchensis) trees growing close to the site of the Turbine

House (Photo 1). Since these are not native to the woodland, they will be removed. A number of

Quercus petraea of native provenance will be planted in tubes in the space created at 2 metre

intervals. This area of the woodland is not grazed, so these tree replacements should establish well.

Photo 1: This group of Sitka Spruce will be removed and Sessile Oak of native provenance planted instead.

3.2.2 Open scrub/woodland mosaic habitat.

Coetir Mynydd also own the adjacent strip of woodland (Parc yr Ynys) enclosing a small tributary

that runs into the Afon Galedffrwd from the west which is shown in Map 3 below.

Map 3: The strip of woodland (yellow boundary) owned by Coetir Mynydd encloses a tributary

that runs into the Afon Galedffrwd. The red line is the approximate penstock route.

Parc yr Ynys is managed as a nature reserve by Coetir Mynydd so they have complete control of its

management. There is a management plan which is now just out of date but is currently in the

process of being updated. There are a number of biodiversity enhancements proposed for this

woodland strip which, incidentally, is managed together with the large Afon Galedffrwd site

adjoining it.

Previous advice from Natural Resources Wales (NRW) encouraged Coetir Mynydd to maintain the

open mosaic habitat at the western end of this reserve. This was largely to maintain the interesting

bryophyte cover of the many glacial erratics that are found here (Photo 2). In the past, this was

achieved by grazing the site and by selective sapling and tree thinning. The wood is divided in half by

a stock-proof fence. The western half was always intended to be grazed, the eastern half ungrazed.

Unfortunately, the past grazier no longer wishes to graze his sheep on the site and Coetir Mynydd

are having problems finding a replacement. As a result, there is a danger that the erratics are

becoming swamped with Bramble (Rubus fruticosus).

Photo 2: An open area at the far western end of Parc yr Ynys (see Map 5) being colonised by dense

Bramble which is threatening to stifle bryophyte growth on the glacial erratics.

Coetir Mynydd will open out three areas of the site at the western end (Map 4) by strimming and

henceforth strimming annually. Arisings will be left on site as habitat piles and allowed to compost

down.

The easternmost of the three areas (Photo 3) is not so entangled with Bramble, although this is clearly creeping in. Here, thinly scattered saplings of Sorbus aucuparia, Betula pubescens and Quercus petraea are growing with Ulex europaeus and U. gallii. The ground cover is composed of Calluna vulgaris, Vaccinium myrtillus, Hyacinthoides non-scripta and bryophyte covered boulders. Here, competing ground cover, principally grasses, Juncus effusus and Ulex europaeus will be cut down to 300mm to conserve the interesting elements of the ground cover and to allow a certain level of tree seedling re-establishment.

Map 4: The three areas to be cleared at the western end of Parc yr Ynys are marked in black.

Photo 3: The easternmost area to be regularly strimmed.

A similar area to the northwest which is currently dominated by Ulex europaeus will also be

strimmed annually.

3.2.3 Woodland Management: bird and bat boxes

On the face of it, the erection of additional bird boxes on the site would be excellent biodiversity

enhancement. However, this may not be currently appropriate within the Parc yr Ocar site: Firstly,

several nestboxes have already recently been erected in the woodland, secondly, there is a great

deal of standing dead wood on the site and much of this wood already contains cavities suitable for

nesting birds (see Photo 5, for example). The woodland will continue to be managed to maximise

natural nest-sites by retaining all dead trees and fallen limbs, and at present there appears to be no

shortage of natural cavities. Recent research that has been carried out in Hungary also suggests that

the breeding success of birds using artificial boxes is not as good as those using natural cavities.

However, five additional bird boxes, and five bat boxes will be installed at the nearby Bradite Works

site where natural nesting-sites are extremely limited.

Photo 5: Natural crevices like this are plentiful in trees in the Parc yr Ynys and Galedffrwd

woodlands.

3.3. Penrhyn Estate land

3.3.1 Ground vegetation along the penstock

Much of the penstock will pass through woodland where both Bluebells (Hyacinthoides non-scripta)

and Wood Anemone (Anemone nemorosa) are growing. Although it is proposed that the pipeline will

be laid on the surface through the majority of the woodland, some ground disturbance will be

inevitable. Coetir Mynydd, during the construction process, have agreed to stock-pile any Bluebell

bulbs or Wood Anemone rhizomes and replant them in the same area as part of post-construction

restoration.

3.3.2 Replanting of Willows (Salix cinerea)

Wet woodland is considered of special importance in Cyngor Gwynedd’s Biodiversity Action Plan.

Photo 6 shows a number of mature Salix cinerea which have fallen across the path of the penstock.

These are marked in Map 5. Inevitably, these trees will have to be removed. Coetir Mynydd have

agreed to negotiate with Penrhyn Estate, who own the land here, to replant three replacement

willows in stock-proof park-style enclosures.

Photo 6: Old Salix cinerea trees that have fallen across the line of the penstock. New trees will be

planted in appropriate enclosures to replace these trees.

Map 5: The location of the fallen Salix cinerea is marked with a red X.

3.3.3 Otters (Lutra lutra)

Surveys have already been undertaken for otters for this scheme and signs of usage of the Afon

Galedffrwd by this species have been noted. A report will have previously been submitted with the

Planning Application.

A careful survey of the penstock route and the main Galedffrwd reserve was carried out by Gritten

Ecology on 15.4.19 and a suitable location was found for the construction of a log pile otter holt (see

Map 6). This will be constructed at approximately SH608657 on the north bank of the river well

away from footpaths and other possible sources of disturbance. It will be built to the specifications

provided by the International Otter Survival Fund.

Map 6: The location of the proposed artificial log pile otter holt is marked with a black X.

3.3.4 Tree planting

Photo 7 shows an area to the western end of the Galedffrwd reserve where Ulex europaeus is

growing in some profusion. This area is also shown in Map 7. Within the stands of U. europaeus,

there are areas of bare acid grassland that lend them selves well to tree planting. Coetir Mynydd

have agreed to plant small groups of native provenance Betula pubescens within dedicated

enclosures since the ground is sporadically grazed. The enclosures would only need to be kept stock-

proof until the trees reach sufficient height to be immune from grazing damage. This ground adjoins

land owned by the Directors of Coetir Mynydd to the north where Betula pubescens has been

planted and is growing in some profusion. Planting trees as Biodiversity Enhancement will increase

habitat connectivity in the area.

Photo 7: Spaces of bare acid grassland within the area of dense Gorse to the left of the photo will

make ideal habitat for the planting of Betula pubescens.

Map 7: The area of dense Gorse to the western end of the penstock (red line) will make ideal

habitat for tree planting.

3.3.5 Agricultural fields at the eastern end of the penstock

Map 1 shows that the penstock will be buried through three areas of grassland at the eastern end of

the penstock route. It has been suggested that these would benefit from management to increase

their plant species diversity. They are already quite lightly grazed and both Crataegus monogyna and

Prunus spinosa are colonising the edges.

Currently, all these fields are owned by the Penrhyn Estate (Map 2) and leased to a local farmer who

wishes to keep them in routine agricultural production. However, Coetir Mynydd have agreed to

hold discussions with the tenant to see if they can persuade him to cease the spread of inorganic

NPK fertiliser on these fields. This would go a long way to improve their floristic diversity.

3.4. Bradite paint works

The Bradite Paint factory in Coed y Parc is likely to be one of the beneficiaries of the hydroelectricity

produced by this scheme and the owners (Little Greene Limited) have generously offered a large

area (approx. 0.5 ha) of their site (which is adjacent to the turbine house and outlet) to be included

in the biodiversity enhancement plan.

Map 8. Bradite Works site

Five suggestions for biodiversity enhancement at the Bradite Works have so far been agreed, but

additional activities are likely to be added as the plan develops, and the managers are enthusiastic to

provide improvements.

3.4.1 Wildflower meadow

A more detailed botanical survey of the grassed area to the NE of the factory will be carried out, but

initial indications are that the area has been re-seeded in the past and currently has a low species

diversity. Currently the area is mowed/strimmed frequently, with all the cuttings left on the surface.

This area will be converted to a wildflower meadow, by preparing the site by nutrient stripping,

followed by an appropriate mowing regime to encourage a more diverse, insect-beneficial habitat.

The managers of the site are keen to encourage butterflies and bees, so choice of any additional

flowering species will take this into account. The site managers, Egni Mynydd will work with the

landscaping contractor to ensure suitable long-term management.

3.4.2 Native woodland tree planting

Additional tree planting at the Bradite Works site will help to provide habitat continuity between the

extensive woodlands at the Galedffrwd Hydro site (Parc yr Ocar) and the nearby Coed Bryn-Meurig.

A small number of trees have recently been planted at the rear of the factory, mainly Alder, Norway

Maple, and Copper Beech. These will be supplemented by native tree and shrub species, including

Oak, Birch, Cherry and Hazel, as well as berry-producing shrubs including Rowan and Elder.

A mature Cherry at the front of the factory has recently died. The bulk of this will be allowed to

remain as standing dead-wood.

3.4.3 Bat boxes

Currently, the factory building, though large, has limited potential for bat roosting sites. Up to five

bat boxes (both wall-mounted and suspended) will be erected under the supervision of a qualified

bat specialist. Long-term monitoring/management of the boxes will also be agreed between a

qualified bat specialist and the owners of the site.

3.4.4 Bird boxes

Few of the existing trees around the site are suitable for hole-nesting birds, and the opportunities on

the buildings are also limited, so up to five artificial nest-boxes will be erected in trees at the

boundaries. Long-term maintenance of these will be agreed between Egni Mynydd and the site

owners.

3.4.5 Control of invasive non-native species

There are a small number of Rhododendron ponticum at the site, but thankfully very few other

invasive non-natives species. The R. ponticum will be removed and replaced with appropriate native

shrub species.

3.5. Control of invasive non-native species (INNS)

There are a number of plants and shrubs of INNS in this woodland, notably Montbretia (Crocosmia x

crocosmiiflora) (Photo 9) and Rhododendron ponticum (Photo 10). Coetir Mynydd have agreed to

remove these plants by appropriate control methodologies.

In addition, there are a number of garden escapes particularly distributed within the woodland east

of the complex of buildings known as Yr Ocar through which the penstock passes. These include

Geranium sp and Buxus sempervirens. These will also be removed.

The owners of Parc Yr Ocar have also agreed for Coetir Mynydd to remove a stand of Yellow

Archangel (Lamiastrum galeobdolon) that is beginning to spread into woodland in Parc yr Ynys (Map

8, photo 8).

Photo 8: Lamiastrum galeobdolon patches will be controlled.

Map 8 Red circle shows areas of invasive Lamiastrum galeobdolon (Variegated Yellow Archangel)

to be cleared

Photo 9: Crocosmia x crocosmiiflora patches will be controlled.

Photo 10: There are several Rhododendron ponticum shrubs that will be controlled.

4. Timetable for biodiversity enhancement activities

Guidance on all aspects of the timing and order of mitigation works and biodiversity enhancement

activities will be taken from a suitably qualified the Ecological Clerk of Works employed on the

project before any works begin.

Enabling ground preparation works will not begin until the end of the bird breeding season (30th

September 2019) and will finish before the following breeding season begins (1st March 2020)

Artificial bat boxes to mitigate lost roost will be erected in suitable nearby trees before any work on

site commences – i.e. July/August before any site preparation in early October 2019.

Artificial bat boxes on the turbine house will be installed at the time of its construction (Autumn

2020)

Artificial bird boxes, if required, will be erected in suitable nearby trees prior to the bird breeding

season (October 2019 – 1st March 2020).

Tree plantings will be carried out in Winter 2019/2020 and winter 2020/2021.

The fish pass and plunge pool will be installed at the time of construction of the intake (Summer

2020)

Ground vegetation – reinstatement will be done in the same growing season as the construction

works (spring - Autumn 2020). Additional enhancement activities will be carried out at the

appropriate seasons for sowing.

5. Aspirations

As mentioned previously, from the outset the entire hydro project is effectively concerned with

biodiversity enhancement and a significant proportion of the profits is intended to be spent on long-

term biodiversity improvement projects in the local area.

Consultations are on-going with other partners and stakeholders for long-term environmental

conservation projects funded by the scheme.

For example, we are currently in negotiations with Craig Shuttleworth at the Red Squirrels Trust

regarding the installation of a Pine Marten box, and if a suitable location can be found on land close

to the pipeline route, then this could be installed when construction work is complete.