Note To Planning Officer Re Mill Stream

8/10/2019 Note To Planning Officer Re Mill Stream

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Beckery Island Regeneration Trust (No 5518679) 01458 831769www.hollinrake.org.uk

Somerset BA6 9EL [email protected]

BECKERY ISLAND REGENERATION TRUST

Mr. Daniel FosterSenior Planning Officer

Mendip District Concil 17thDecember 2014

Land adjacent to Baily's Tannery Beckery Old Road Glastonbury BA6 9NY

The construction of 12 no. houses with associated parking, access and landscaping. |

2014/2420/FUL

MeetingDate:Saturday 13thDecember

Time:9:30am

Present:

Henk Strick Mendip District Council Conservation Advisory Panel

John Brunsdon Mendip District Councillor for Glastonbury; BIRT

Ian Tucker Glastonbury Town councillor for Glastonbury; BIRT

Charlie and Nancy Hollinrake BIRT; archaeological consultants

Ian Fear Glastonbury Conservation Society chair

Purpose: to discuss management of the Glastonbury mill stream

1.0 Background

The Glastonbury millstream passes through the property subject to the above planning

application, at which point it bifurcates into two channels which rejoin before leaving the

site. The proposed development is shown in Figure 1. The proposal includes the infilling

of one of the mill leats. The meeting was held to further discuss the reasons behind the

infilling of the leat and to explore alternative scenarios for managing the mill stream.

The mill stream is discussed in the following documents submitted with the planning

application:

the Design and Access statement prepared by the architects Architecton;

the Archaeological Assessment prepared by C & N Hollinrake, consultant

archaeologists.It became obvious, however, that most of the issues surrounding the mill stream had been

covered in the planning application, but that it was difficult to extract the discussion of the

mill stream from the application documents. The following note on the mill stream has

been prepared to facilitate discussion of the mill stream and to address the issues

surrounding its future management. It is intended to act as a supplement to the two

documents already submitted


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Figure 1. Plan of the proposed development. (courtesy of Architecton)


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2.0 The course of the mill stream

Figure 2. Map of the Glastonbury mill stream taken from the Glastonbury and SharphamDrainage Board website.

The mill stream, constructed by Glastonbury Abbey in the late 12 thcentury to run its mills

at Beckery and Northover1, runs from Clyce Hole on the River Brue, follows the 10m

contour around Wirral park and then travels west past the Great Withy Rhyne to rejoin the

River Brue at Cold Harbour.

1Seethe Archaeological Assessment prepared by C & N Hollinrake, consultant archaeologists


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2.1 Clyce Hole

1886

1930

Figure 3. A montage of O.S. maps

of Clyce Hole shows the changes tothe clyce in recent years. The mill

stream was traditionally managed

using a system of weirs and sluices,

regulating the quantity of water

entering the millstream in times of

flood and drought. In recent years

the main consideration has been to

manage the mill stream to prevent

flooding. To ensure against this, an

earth dam has been installed

incorporating a throttle pipe.

Magic Maps The new dam is 24.8m wide. The red line marks the GlastonburyStreet

parish boundary.


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The effect of the throttle pipe is to reduce the amount of water flowing through the mill

stream. By November 2013, the throttle pipe had been substantially blocked by silt which

greatly impeding the water flow. The following photographs show the effect this had on

the structure of the millstream.

The dam on the Glastonbury Millstream,

looking west.

Stagnant water collecting just down-

stream of the dam was saturating thebank and causing it to collapse.

Figure 4. Photographs of the dam containing throttle pipe before the silts were cleared.

However, as a consequence of a meeting held near the Glastonbury Lake Village between

the Upper Brue Drainage Board, the Glastonbury Antiquarian Society and the local

farmers on the 21stNovember 2013, the silts upstream from the throttle pipe were cleared

away, allowing the water to flow more freely. This flow is likely to be maintained in the

future for the benefit of farmers in East and West Waste, where the Glastonbury Lake

Village, which requires a high water table for its continued preservation, is situated.

2.2 The Environment Agency has informed the riparian owners of the new units on theMoorlands site that they will be responsible for the maintenance of the channel in the

future. The management company has now been set up. There will be eight or nine joint

riparian owners responsible for the maintenance work.2 BIRT owns two properties along

the Glastonbury mill stream Northover Mill and the Bailys Buildings, and the

Glastonbury Antiquarian Society owns the field containing the Lake Village; since there is

overlap between membership of both societies we will be taking a close interest in future

management of this waterway and may consider chairing the management committee when

it is operational.

2Minutes of the Brue Catchment Meeting, Glastonbury Town Hall Tuesday 12 November 2013 at 10.30

am


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3.0 The mill stream at Bailys

When BIRT acquired the Bailys Buildings in July 2011, the buildings came with the

responsibility of cleaning and re-modelling the millstream under the supervision of the

Environment Agency, which is now completed. The works spread beyond the Bailys

Buildings as far as Northover Mill. The remodelling was designed to ensure sufficient

flow in the mill stream to avoid the build-up of silts, ensuring minimal future management

requirement. The banks of the mill stream were consolidated with special matting

incorporating seeds, roots and corms of native wild species to enhance the ecological

potential of the waterway.

3.1 The mill stream as it passes through the site of the potential development

The mill stream changes its character where it passes through the site of the proposed

housing: this is the only place on its course where it splits into two channels. The

archaeological assessment submitted with this planning application details how these two

channels appear in all the historic maps since 1610 and appears to be part of its original

design. The layout is most clearly depicted in the 1886 O.S. map, enhanced with colour.

Figure 5. O.S. map 1886. Identifiable

buildings have been marked in orange.

By 1886 Beckery Mill had been extended

across the main branch of the millstream

to the bank of the relief channel. The mill

stream has been coloured blue. Its

location in relation to the flour mill,

which incorporated the medieval mill

building, demonstrates that the easternchannel of the stream acted as a relief leat

for use when it was necessary to stop the

turning of the mill wheel. Normally, the

water would have flowed through the

western channel. A pond can be seen in

the western channel below the mill wheel.


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4.0 Management of the mill stream within the development site: the issues

4.1 Water Volume

The management of the mill stream relies on a flow sufficient to flush out silts which

might otherwise block the stream. Yet the new structures installed at the source of thestream at Clyce Hole limits the amount of water entering the mill stream; there is now less

water flowing in the stream than when it was originally designed.

Issue: There is insufficient water entering the mill stream to be able to send enough

water through both channels of the mill stream to avoid silting in one or both

channels.

4.2 Original Design

The two channels of the mill stream were never intended to both carry water at the same

time. The eastern channel is a relief channel for use when it was necessary to stop the millwheel.

Issue: It was never intended for both channels of the mill stream to be flowing at the

same time.

4.3 Ecological Potential

On the day of the survey the water depth [in the relief leat]was between 0.15m and 0.5m.

The water had very low turbidity. The stream bed varied in composition but was mostly

covered in a shallow layer of silt. Some areas however were stonier. The result of the

proposals would be that the river would run through the pond and over the sluice wall.This would mean that the connectivity of the stream would be retained. It would also mean

that instead of there being two separate pond and stream to form one water body.

The ecological conditions (such as flow rate and substrate character) of the combined

water body, will vary at different points along its course. Whilst the modified structure of

the water course will be different to its pre-development structure, it will continue to have

high potential to support a diverse assemblage of plants and invertebrates, providing that

the structural design, hard landscaping and soft landscaping is carefully planned,

implemented and managed.4

Issue: Management should preserve and enhance the environmental potential of the

site.

4Baker, Mark, 2014, ECOLOGICAL SURVEY: LAND OFF BECKERY OLD ROAD, GLASTONBURY,Michael Woods Associates, Ecological Consultants


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4.4 The Wessex Water storm water drain and filter bed

The storm water flowing from the main industrial site is likely to occasionally introduce

some pollutants from the historic industrial activities, hence the reed bed. At present, this

potentially contaminated water is open to the sky and can be accessed by wildlife,

domesticated animals and people. The water in the relief leat is turbid and low in volume,although during periods of high rainfall this tendency is reversed. This issue is lessening

through time as the pollutants, most of which are heavier than water, sink to the base of the

soft alluvium filling the industrial site.5

Issue: Storm water from the industrial site is likely to carry pollution, which is

accessible by wildlife.

4.5 Archaeological and Historic Significance

The mill stream is a major archaeological feature created by Glastonbury Abbey in the late

C12th century, recognized in the Historic Environment Records. This area where itbifurcates is an important part of the original design concept and an example of medieval

industrial engineering in a location where it is easily available to the public.

Issue: Management of the mill stream must preserve and enhance the archaeological

and historic value for public enjoyment and understanding of their significance.

4.6 Occupants of the surrounding houses

The water flowing in the relief leat, indeed, the depth of the leat itself, presents a hazard for

those living in the surrounding houses, especially the children. The stagnant pond in the

main leat breeds multitudes of mosquitoes and midges. Both leats are unfenced and easilyaccessible.

Issue: The present arrangement of the mill stream constitutes a health and safety

hazard for occupants of the surrounding houses.

5Colin Burgess, contamination consultant, pers. comm..


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5.0 Management of the mill stream within the development site: the proposalThe planning application includes proposals for management of the historic mill stream

that addresses the issues outlined above.

5.1 The mill stream is to be re-directed back to its original main channel.

This deals with issues 1, 2, 3 and 6.

5.2 The Wessex Water storm water drain is to be diverted into a buried pipe, with the

filtering reed bed to be relocated to the north of the site just before this water joins the mill

stream. This is immediately up stream from the issue from the sewage farm into the mill

stream where any surviving pollutants can be diluted by the increased volume of water.

Moving the reed bed ensures that the swamp habitat is preserved.

This deals with issues 3, 4 and 6.

5.3 The relief leat will be used to carry the coils from the heat transfer heating system

to be installed in the houses. The stone walls cladding the sides of the relief leat will be

recorded using photographs and inspection notes before being backfilled.

Not only will the relief leat be re-used for a modern purpose, it will be preservedboth below ground and on the record. Nothing will be done to the relief leat that could not

be reversed at a later date.

This deals with issues 1-6.

5.4 Publication of the archaeological and historical significance of all of BIRTs work

at Beckery will be in a variety of forms, from scholarly and technical papers to non-

technical leaflets and pamphlets. A story board next to the site would make the heritage of

the mill stream available to the passer-by. Finally, the profits from the new housing will be

diverted into the renovation of the Bailys Buildings, which are designed to incorporate an

archive centre and exhibitions for public use where all of the information relating to the

heritage of Beckery will be curated and displayed. Please refer to the attached projectsummary for information about BIRT and the larger Bailys project.

This deals with issue 6.

6.0 ConclusionThe management of historic assets is often a question of managing change, as is recognised

in English Heritage guidelines.6 Usually, the best way of ensuring sustainability in the

management of historic sites is to put them to modern use which helps them to pay their

way. As a conservation trust, BIRT have made concerted efforts to design a project that

offers suitable, appropriate management of change to ensure the sustainability of a heritage

property we intend to hold and manage for the foreseeable future. We realise that there is

no one right way to achieve our objectives so we welcome informed input from all

interested parties.

Nancy Hollinrake

Beckery Island Regeneration Trust

Glastonbury Antiquarian Society

6 Conservation Principles, Policies and Guidance for the Sustainable Management of the Historic

Environment, English Heritage, 2008.


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Note To Planning Officer Re Mill Stream

Documents

Transcript of Note To Planning Officer Re Mill Stream