archaeological evaluation for angidy hydro scheme

7/27/2019 Archaeological Evaluation for Angidy Hydro Scheme

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Report No. EVTP/TAP/08Jan 2009

A.P.A.C. Ltd.

Archaeological Perspectives Analysis Consultancy

ARCHAEOLOGICAL

EVALUATION


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A.P.A.C. Ltd Tintern, Angidy, Hydro-Electric Project EVTP/TAP/08

Summary

In May, 2007, Dr N Phillips of A.P.A.C. Ltd, was contacted by Mr. P. Powel, of

TAP Ltd, in relation to proposed work to be undertaken in the Angidy Valley,

Tintern. The proposed work involved the instillation of approximately onekilometer of water pipe, along the former leat system belonging to the Angidy Iron

Works. The proposed water pipe will be used to harness the renewable power of

the Angidy stream in a Community Owned Hydro Electric Project.

Since the initial contact, Dr Phillips has had a continuing role in the project;

undertaking in the first instance the production of a program of desk top and field

evaluation prior to commencement of ground works.

This present evaluation report was prepared in consultation with the earlierevaluation work, a desk base assessment and with advice from GGAT and Cadw at

the site meeting on 15th

July 2000.

The purpose this evaluation is to describe a course of action which seeks to best

elucidate the nature of the archaeological resources present in such a way as to

inform and guide the work to be undertaken.

The five test pits excavated for this evaluation have produced important

information as to the archaeological resources that remain along the evaluationh ll b d h d k


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C O N T E N T S

Page

1. INTRODUCTION ........................................................................................................ 42. LOCATION AND DESCRIPTION OF THE EVALUATION AREAS ........................... 43. BRIEF ARCHAEOLOGICAL AND HISTORICAL BACKGROUND ........................... 54. RATIONALE OF THE PROJECT............................................................................... 55. AIMS AND OBJECTIVES .......................................................................................... 6


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List of Figures

Figure 01 Location MapFigure 02 Trench location plan and proposed pipeline routeFigure 03 Harris MatrixFigure 04 Schematic plan view, Evaluation Trench CFigure 05 Schematic section, Trench E

List of Plates

Plate 01 Trench A, View south east, topsoil removal

Plate 02 Trench A View east context [101] stone inclusions


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1. INTRODUCTION

This evaluation report has been produced from site work which was outlined in ArchaeologicalEvaluation Design, EV/TAP/07, revised EV/TAP/08, July 08, submitted by Dr Neil Phillips, A.P.A.C.Ltd, in response to a proposed programme of works at the Angidy Valley Tintern, (NGR SO 513003), fig 01. The proposed programme of works will involve the excavation of a trench, in which awater pipe for a hydro-electric community project will be laid.

The client; Tintern Angidy Project Ltd, (TAP), is seeking planning permission from MonmouthshireCounty Council (MCC) for the building of the hydro electric turbine and associated structures, whichare to be situated on the south bank of the Angidy River. The proposed pipeline can be seen in fig02. The works will connect from the Beaufort Dam in the west, passing through the Angidy FurnaceSite, Scheduled Ancient Monument MM197, to the point where the forestry track meets the road tothe east of Furnace Farm. A water supply for the turbine will be tapped and piped from the Beaufortpond. It is proposed that the pipe will be laid in such a way as to minimise any disturbance toarchaeological resources present. To do this it will be necessary to sink the pipe within the run of theoriginal leat system associated with the wire works.

In order to determine the type of archaeological resources present; Dr Phillips; during a site visit withTAP members and representatives of GGAT (Glamorgan Gwent Archaeological Trust) and Cadw,reaffirmed that a series of evaluation trenches along the course of the proposed pipe line would beextremely enlightening at the pre-excavation stage of the development. Such a procedure ofevaluation would provide information upon which to inform and guide any further development.

The revised evaluation proposal, EV/TAP/08, set out a methodology for a test pitting strategy; basedon information as to the proposed development, provided by (TAP), the results of a program of sitevisits a Desk Based Assessment DBA/TAP/08 February 2008 and guidance from GGAT and


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B, was sited approx 108m down stream, east of the Beaufort Pond. B was 3m x 1m

northeast/southwest. Its position was sited between a dry-stone revetment wall to the southand a line of stone to the north. The trench at this point sought to provide a complete sectionthrough the leat. Proberts excavation report suggests that the leats were stone edged andlined in clay (Probert 1982, 13).

C, 3m x 1m northeast/southwest, was sited approx 10m west of the scheduled area. Itsposition was sited to the west of a depression in the ground, along the footpath, which may beassociated with the east end of the leat terminal basin (Pickin 1982).This is the area at whichit is proposed for the water pipe to deviate from the leat path in order to pass around thescheduled area.

D, 3m x 1m north/south, was sited approx 47m down stream, east of the Furnace Farm Pond.The position for D was between an earthen cut to the south and a stone edging north. Thetrench here sought to provide another complete section through the leat.

E, 3m x 1m north/south, was sited approx 125m down stream, east of the Furnace FarmPond. Trench E was sited between an earthen cut to the south and a dry-stone wall to the

north. Again, the intention was to gain a complete section through the leat.

Evaluation trenches were not excavated beyond the required pipe depth, which is the maximumdepth required by the pipe trench and varies throughout the site, (EV/TAP/08, fig 02).

Within the depth parameter, it was possible to understand the character, distribution, extent andimportance of at least the minimum number of archaeological features. In each trench, sufficientexcavation was undertaken to reach either a significant archaeological horizon or the required depthmark. No evaluation trenches were excavated beyond the point at which safety would have been atrisk


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5. AIMS AND OBJECTIVES

In accordance with revised Project Design (EV/TAP/08), this test trench evaluation programme:

Has elucidated the character, distribution, extent and importance of the known and potentialarchaeological remains, which exist in the development area.

Resulted in the production of this report which provides sufficiently detailed information toallow informed decisions to safeguard the archaeological resource, to be taken on the basis of

its contents.

Has specifically established the presence and extent of significant archaeological deposits,features and structures.

Recovered enough information to enable assessment of the archaeological implications of thestudy area.

6. METHODOLOGY

The evaluation trenching consisted of the excavation of five trenches 3m x 1m, fig 02, (parts of whichwere excavated to the base of the archaeological resource).

All trenching was undertaken manually with resultant archaeological resources being cleaned, wherepossible, for recording.

All contexts were recorded [###] on pro forma context sheets.


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A gradual, feathered change of stratigraphy was noted at about 700mm with a change to redsandstone/silt with angular small slabs of sandstone [102]. Context [102] was only reached at thesouthern end of the trench and is associated with the eroded layer of sandstone clay/silt [103] abovethe underlying, natural red sandstone (BGS 1981).

It was noted that context [102] tended to slope down towards the north of the trench but it was notpossible to verify its extent due to flooding, plate 03. A depth of 1.1m was reached in the north endof the trench but the fill remained entirely context [101].

No evidence of any structure was found within Trench A.

Finds:

Only two finds were present in trench A, both plastic and both came from the feathered interfacebetween [101] & [102], at approx 700mm.

The first, a 200mm length of white plastic tape 20mm wide can be seen in situ in plate 03; above andto the right of the mud puddle at the back of the trench.

The second find, a piece of pale blue and white, Smith and Co Salt and Vinegar crisps wrappercarrying the Keep Britain Tidy logo and a best before JULY 80 instruction, was found in closeproximity.

Interpretation:

The ground level at trench A is noticeably higher than the rest of the path where the leat was


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Between the two retaining walls, the deposit of red sandstone/silt [102] was carefully removed;

reaching a depth of 250mm in the north of the trench but rising to 120mm in the south. The northernedge of context [102] also contained a few angular red sandstone slabs, plate 06.

Beneath [102] was context [103] a compacted natural sandstone/clay. A small test-pit 400mm x400mm was excavated into [103] to a depth of 200mm, plate 07. The test-pit was excavated toinvestigate the structure of wall [104] and the consistency of context [103].

The small test-pit revealed [103] as a consistent fill of compacted red clay/silt with no finds or

inclusions. The test-pit also revealed that wall [104] bas built directly on top of [103] and that asealing layer of yellow clay [106] had been used on the joint.

At the south end, the retaining wall [105] was also built directly on [103] but this time with no sealingclay was found.

The distance between the two retaining walls is 2.3m and the maximum depth is on the north edgeat 200mm. The floor of the leat is the natural compacted red sandstone clay/silt.

Finds:

Two small pieces of blue/green furnace slag were found on the upper surface of [104].

Interpretation:

The two retaining walls [104] & [105] clearly form part of the leat system providing a lined channel forthe water to pass along. The southern wall [105] retains the bank above the leat and the naturalsandstone base slopes down gently from the base of the wall [105] to the base of wall [104].


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The northern edge of the wall can be seen butted against red, re-deposited, natural clay [108], plates

08 & 09. Context [108] contains charcoal inclusions making up c 40% of the matrix and visible asextensive black staining.

The south western edge of wall [107], plate 09, shows a semi-circular area of dark brown soil [109]cut into [108]. This area of dark brown soil was excavated to examine its purpose and to betterunderstand the nature of the wall and its depth at this point.

The deposit [109] was found to contain pieces of rubble in the form of small irregular, angular, slabs

of red sandstone in a dark brown soil matrix.

The wall [107] was explored to a depth of 800mm at which point natural was reached. The wall has astepped construction on the north and therefore outer edge; a good design for a containmentstructure, plate 10. The outer face was also not as well dressed as that on the inner side of the wallsuggesting that it was not meant to be exposed.

A schematic plan of the trench can be seen in fig 04

Finds:

A few small pieces of blue/green furnace slag and charcoal were found in [108].

Interpretation:

The wall [107] clearly forms part of the northern leat wall. Its structure is for the most part intactbeneath ground level and still able to retain water as evidenced in plates 08 & 09. Its construction isfaced stone with rubble fill in a sealing clay matrix. The outer edge is stepped, which may be for

strength or co ld denote that the e al ation trench as e ca ated at a con e c r e of the all or


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two pieces of un-burnt charcoal, plate 12. After excavation had been completed, it was noticeable

that context [111] was noticeably horizontal in deposition in comparison to the convex fills above andbelow.

The hardness of [111] dictated its excavation using a pick axe which took a great deal of time. Withthis in mind and worsening daylight, it was necessary to reduce the trench width to 0.5m, plate 13.

In the south end of the trench, at approximately 600mm depth, context [111] was found to be directlyabove [103] the natural compacted sandstone context also seen in trenches A & B. Context [103]

however, sloped down to the north reaching a depth of 1m approximately 1m from the north edge ofthe trench.

At approximately 600mm from the south end of the trench a new context was encountered beneath[111] and above [103]. This new context [112] consisted of a dark red, hard compacted, coursegrained fill, plate 11.

The stone edging structure to the north was not confirmed within the confines of the trench.

Finds:

Two small lengths of un-burnt charcoal were found at the top of [111]. They were some 180mm inlength and 30mm in diameter.

Interpretation:

No evidence of any built structure was found within this trench. What was found was a heavilycompacted fill overlaying an event during which ferrous material was allowed to collect and

lid t t f fl Th i l i f h l d h l fl k i di t th t thi f


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Beneath the topsoil and extending to a depth of 400mm was a heavily compacted context of redsandstone clay/silt containing few stones [110], plate 15. This context was identical to that found intrench D but not quite as deep. Context [110] again had to be removed with a mattock and again itoverlay a hard orange/red granular context identical to [111] in trench D.

Relying on experience gained in trench D, the hardness of [111], led to the sectioning of the trenchalong its length, to allow for the increase in time taken to pick axe through the consolidateddeposition, plate 14. Identical to the findings in trench D, the depth of [111] was approximately200mm and its deposition was as a horizontal band.

At the south end of the trench, at approximately 500mm depth, context [111] was directly above[103] the natural, compacted sandstone context also seen in trenches A & B. Context [103] curveddownwards towards the centre of the trench reaching a maximum depth of 1.32m, 1m from the southedge.

At the north edge of the trench E, was feature [114], a dry-stone retaining wall to a considerablebank of material between the path and the Angidy River, plate 16. The wall, some five courses high,was constructed on top of a bank of dark red clay [115] starting at a depth of 200mm beneath the

present topsoil. There was no evidence of any sealant used between the joints of the wall or as a fillbetween the wall base and the red clay surface.

Context [115], a hard red clay with no inclusions, forms the base for the wall [114], dropping almostvertically for about 225mm before tapering out towards the centre of the trench at a depth of 1.31m.There were no tooling or application marks on the surface of [115].

Context [112], again identical to that found in trench D, occupied the space between [111] and [103]

& [115]


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construction of the road link across the Beaufort Dam in the 19th century and possibly more recent

work has effectively removed all trace of the upper leat system.

The four trenches that did expose parts of the leat system have shown that construction techniquewas to revette a natural sloping bank of red sandstone/clay, with an outer bank and/or wall of clayand stone to form a channel. The channel seems for the most part to have been about 2.5m wideand survives to a depth of about 200mm.

9. PREDICTED IMPACTS OF THE PROPOSAL ON KNOWN ARCHAEOLOGY

The known impact of the proposal on the archaeology is that the excavation for the pipeline willexpose the entire length of the two suspected but previously un-corroborated leat systemsassociated with the Angidy furnace and Furnace Dam sites.

Carefully conducted, there should be little detrimental impact on the known archaeology. Theevaluation has shown that the internal floor of the leat is a natural surface and as the excavationtrench will be considerably less than the width of the leat; a carefully directed cut along the centre of

the leat should leave the archaeology intact.

However, two potential problems should be highlighted:

On the Beaufort Dam leat, stretches of the path are too narrow at present to have accommodatedthe 2.5m leat. Either the south bank has slipped and buried some of the leat or the north edge of theleat has eroded. In either case, some damage may be caused in tracing where the leat is at thesepoints. Conversely, the excavation does provide a chance to record these potential areas wherearchaeological resources may be being lost.


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Close watching brief cover during excavation of the leat between the Beaufort Dam and theAngidy Furnace.

Close watching brief cover during excavation around the edge of the scheduled site.

Close watching brief cover during excavation of the ground along the side of the Furnacepond.

Close watching brief cover during excavation of the ground and leat from the furnace pond to

the proposed turbine house.

Close watching brief cover on excavation work for the turbine house.

A watching brief for the work between the road, to the east of the Furnace Pond, can becovered on an on call basis.

11. ARCHIVE

Monmouth Museum has been notified of the intention to deposit the project archive and this hasbeen accepted.

The project archive will consist of all original records, artefacts, ecofacts/samples and alldocumentation that relates to the evaluation. Copies of the WSI and any relevant correspondencewill be included. The Archaeological Contractor will endeavour to persuade the legal owner of anyartefacts, to transfer them to Monmouth Museum.


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13. BIBLIOGRAPHY

BGS 1981. British Geological Survey 1981. England and Wales Sheet 250 Chepstow. Solid and DriftGeology 1:50 000.

Cadw. Angidy Ironworks MM197(MON).

Doc 53. Paar, H.W., & Tucker D.G., The Old Wireworks and Mills of the Angidy Valley at Tintern and

Monmouth (Typed manuscript, draft with hand written notes).

Pickin, J., 1982. Excavations at Abbey Tintern Furnace, Journal of the Historical Metallurgy Society V16.2.

EV/TAP/07. Project Design of an Archaeological Evaluation Programme For A Proposed PipelineAlongside The Angidy River, Tintern. (Phillips, N., 2007)

DBA/TAP/08. Desk Based Assessment, Proposed Hydro-Electric Project Angidy River Tintern. (Phillips,

N., 2007).

EV/TAP/08. Project Design of an Archaeological Evaluation Programme For A Proposed PipelineAlongside The Angidy River, Tintern. (Phillips, N., 2007)

Probert, G., (1982), Excavations of Abbey Tintern Ironworks. Gwent County Hall. (Unpublished held atMonmouth Museum).


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archaeological evaluation for angidy hydro scheme

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