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Netherby, Castletown Isle of Man
Written Scheme of Investigation for a programme of Archaeological Monitoring and Excavation
Date: 26/06/2023 Applicant: Julie Walker/ IAC Archaeology
This Written Scheme of Investigation (WSI) relates to archaeological monitoring and subsequent excavation of archaeological features identified during testing at Netherby, Castletown in advance of the construction of an approved residential development. The site is located approximately 1km northeast of Castletown, accessed off the A5 and opposite the Ronaldsway Airport at NGR SC 27390, 68500. Excavation follows on from previous trial trenching (OA 2021) and geophysical survey (Chapman and Mytum 2015) and is being carried out to address a condition placed upon the planning consent for the site. The condition (Condition 6) reads:
‘6. No development shall commence on site until a programme of archaeological work, to include excavations where required, has been submitted to and approved in writing by the Department. The programme shall include the degree of supervision by a qualified archaeologist. Development shall be carried out in accordance with the approved programme.
Reason: To ensure that any archaeological remains and features are properly recorded.’
RPS, in consultation with Andrew Johnson of Manx National Heritage (MNH), agreed that an area of 4238m2 will be subject to topsoil stripping and detailed archaeological excavation. All archaeological features identified within this area shall be subject to investigation and recording. In addition, the line of a sewer outflow pipe shall be subject to a watching brief with any subsequent archaeological remains including possible human remains being fully investigated and recorded.
FIGURE 1: Site Location showing agreed excavation area
The proposed development comprises a residential housing project and associated infrastructure within a 1 ha site. The construction methodology will require excavation for foundations/ stripping topsoil; which will have a direct negative impact on archaeological remains identified within its boundary.
FIGURE 2: Plan of development
The excavation area is located in the southeast of the Isle of Man, a landscape rich in archaeological heritage. The site is situated within the former grounds of a domestic property known as ‘Netherby’. The topography of the site is flat while the underlying geology is recorded as Knockrushen Formation: Limestone interbedded with argillaceous rocks (British Geological Society).
A desk-based assessment produced by Manx National Heritage in 2014 was summarised by OA in their evaluation report (2021). In short, the excavation site is located in a landscape characterised by low hills and shallow valleys which shows evidence for human occupation/ alteration for over the past 10,000 years. Several archaeological investigations have taken place within the immediate vicinity of Netherby including at Billown Lime Quarry and at Ronaldsway Airport. Early medieval burials were also uncovered adjacent to the current site and the potential for uncovering further human remains is high. Archaeological activity dating from Mesolithic hunting/ gathering through to post-medieval settlement has been uncovered within the environs of the current site.
In 2015 a geophysical survey was undertaken by the Centre for Manx Studies (Chapman & Mytum) within the development site. Several anomalies indicating enclosures and associated features were identified. These anomalies were subject to an archaeological evaluation in 2021, carried out by Oxford Archaeology. A total of 13 trenches, amounting to 210.9m2, were mechanically excavated
across the development area. A representative sample of features was excavated to characterise the nature of the archaeological remains.
The archaeological features were easy to identify against the underlying geology and can be summarised as follows:
All uncovered archaeological features corresponded well with the geophysical anomalies.
A number of tree preservation areas have been identified around the excavation site. A suitable topsoil stripping strategy has been discussed and agreed between RPS and Andrew Johnson which will involve excavation of one half of the site with stockpiling of spoil on unexcavated half. Once excavation of archaeological features in the first half has been completed and signed off by MNH, this will be backfilled to allow stripping of the remaining half of the site.
4 EXCAVATION STRATEGY
Excavation will involve preservation-by-record through appropriate rescue excavation of all archaeological features or deposits discovered by earlier investigations, so as to mitigate impacts on the archaeological remains within the footprint of the development.
As noted above, the site will be excavated in halves. Each excavation area will be mechanically stripped of top and subsoil to the level of the archaeological features. The material overlying the archaeological deposits includes turf, a bedding sand for turf, top and subsoil. The top and subsoil ranges in depth from 0.15m to 0.5m. The stripping will be undertaken by a tracked excavator fitted with a toothless grading bucket. Top and subsoil will be removed from the excavation areas in level
spits of 0.1-0.15m in depth and deposited in separate dedicated stockpiles. This stripping will be subject to constant archaeological supervision and direction to ensure that the upper levels of any features are identified as early as possible. The archaeological monitoring will be undertaken in accordance with the guidance provided in the Chartered Institute for Archaeologists (CIfA) document ‘Standard and guidance for an archaeological watching brief’ (2020a).
All relevant and applicable health and safety legislation, regulations and approved codes of practice will be respected, and all health and safety procedures established by the groundworks contractor and/or the developer will be adhered to.
Reasonable access to the development site will be made available to the MNH Inspector who may wish to be satisfied that the archaeological monitoring and excavation is being undertaken in accordance with the methodologies set out in this WSI.
The areas subject to mechanical stripping will be excavated to no more than 1.2m in depth. Deeper excavation, requiring shoring or stepped sides, is not anticipated.
The on-site archaeological recording and recovery techniques will be in line with this WSI and current industry best practise and shall be fully understood by all.
All paper and digital records made during the course of the archaeological excavation, and the treatment of artefacts and environmental remains, will be reviewed continuously. Record checking and collation will be completed at regular intervals, as appropriate, and before an area is considered complete, abandoned, backfilled or the site closed. Errors or omissions in recording discovered during post-excavation cannot be recovered.
All investigation of archaeological levels will usually be by hand, with cleaning, examination and recording both in plan and section.
Within significant archaeological levels, the minimum number and proportion of features required to meet the aims of the investigation will be hand excavated. Pits and postholes will usually be subject to a 50% sample by volume, at sufficient frequency to characterise the archaeological activity across the site. Linear and curvilinear features will be sectioned as appropriate. Hearths, stakeholes, and domestic spreads will be subject to 100% excavation.
More complex features such as those associated with funerary activity will usually be subject to 100% hand excavation. Should the archaeological content or value of a feature warrant further investigation at the evaluation stage, IAC Archaeology will liaise with MNH to ensure that all features are excavated appropriately and to their satisfaction – so as to ensure that they can be fully characterised. This may mean that the excavated percentage of each feature may increase or decrease as required.
Where deposits are investigated, and found to be undated, and where these have the potential to be of archaeological significance (e.g. of earlier prehistoric or early medieval date, or any other deposit types notable for artefactual scarcity) appropriate samples should be
taken for artefact recovery. The soil should be hand excavated and then sieved or screened through ¼” or 6mm wire mesh to recover artefacts. Samples will be retained for immediate sieving off-site.
All excavation shall be undertaken in accordance with best professional practise and guidance provided by CIfA (2020b).
All archaeological features and deposits will be fully excavated by hand and will be photographed, drawn and recorded. The composition, stratigraphic relationships and interpretation of all contexts will be recorded on pro forma context sheets during excavation. The soils and geology will also be recorded.
A detailed and comprehensive recording process will be maintained, to include the use of specific pro forma registering systems such as context records, sample records, drawing records, photograph records, human remains records, wood/timber records (if required), masonry records (if required), finds records, etc.
Comprehensive plans and cross-sectional drawings will be produced at a scale of 1:10, 1:20 or 1:50 as appropriate. Digital camera equipment will be used, and each feature will be recorded threedimensionally using a combination of scaled drawings and surveying equipment. Photographs shall include a north point, photo board and appropriate ranging rod/scale. Digital cameras will have a pixel count of no less than ten million pixels. Photographs that help to contextualise excavated features in their local environment will also be taken.
All site surveying works will be undertaken using GPS surveying equipment and related to Ordnance Datum and NGR. Site plans will record all identified archaeological features, and these will be scanned, digitised and georeferenced to NGR projection. The location of all finds and samples will be precisely georeferenced using a GPS.
Finds will be housed temporarily on-site and thereafter stored at an appropriate location with facilities to ensure their proper storage. Removal of objects from the island will be done under licence to MNH.
The identified human remains (Sk xx-xx) will be exposed carefully by hand, using tools that are sensitive to the condition of the bone so as to avoid causing damage. Each complete or partial skeleton will be designated a Sk number, and any disarticulated remains will be given a Dsk number. All human remains will also be given an individual context number in the main site archive. A separate skeleton register will be maintained on site, noting the context, grave cut, grave fill, age, sex, orientation, preservation, completeness of the recorded individuals; and any other interesting features such as associated artefacts. The human remains will be recorded on IAC’S pro-forma ‘Skeleton Record Sheets’ based on the example produced by the Irish Association of Professional Osteoarchaeologists (IAPO).
Early identification of the body position will aid in the careful excavation of the skeletons. Every effort will be made to determine the cut of the grave, however where fills are indistinct from the surrounding soils this may be difficult. Partial recording of a grave will be avoided where possible.
The excavation methodology will follow a similar pattern for each skeleton, aiming to expose the head, shoulders, long bones of the limbs, hands/feet and torso, in that order. The latter areas are often more susceptible to deterioration and exposure should be limited. Should archaeological objects be found in association with the individual, an assessment will be made as to the best method of recording and lifting, so as to avoid any negative impact on the human remains or the artefact. Record will be made of any pathological or developmental conditions that are evident in the ground, and onsite dimensions may be recorded for fragmentary remains to provide an approximate indication of stature.
The skeletal remains and grave will be hand drawn at a scale of 1:20, and the graves will be recorded by photogrammetry. Additional record photos will be taken of the burial, including detailed views of any interesting skeletal features or body positions.
Once fully recorded in situ, the remains will be lifted by region and put in labelled bags, within a sturdy container for removal to the post-excavation facility. Any excess soil will be removed from the bones during lifting and bags will be pierced for breathability, to reduce the potential for deterioration. Bagging recommendation: 1. Skull, 2. Mandible, 3. L clavicle and scapula, 4. R clavicle and scapula, 5. L arm, 6. R arm, 7. L hand, 8. R hand, 9. Sternum, 10. Spine, 11. L ribs, 12. R ribs, 13. Sacrum, 14. L. Pelvis, 15. R. Pelvis, 16. L. Leg, 17. R Leg, 18. L foot, 19. R foot, 20. Disarticulated or associated remains.
Soil samples may be taken around the position of the hands and feet once the bones are lifted if there is a query over the identification of these elements on site. These samples will be dry-sieved in post-excavation to maximise collection of small bones which can be easily perceived as stones in some site conditions. Soil samples may be taken from the abdomen area if there is potential for foetal remains to survive, this will be advised by the osteoarchaeologist on a case-by-case basis (e.g. if the individual has been identified as a probable female). Further sampling may be deemed necessary based on the excavation findings, such as to investigate potential organic deposits within the grave fill, or to ensure collection of fragmented artefactual remains.
The human remains will be removed from site to IACs post-excavation facility at Kilcoole, Co. Wicklow as soon as possible. The bones will be stored in a dry stable environment until an agreement on post-excavation strategy has been approved by all parties. The post-excavation proposal will include a list of potential further analyses to be carried out in addition to osteological assessment and a rationale for same; such as radiocarbon dating, multi-isotope analysis (to determine in-vivo mobility or diet/health), peptide analysis of tooth enamel (to determine sex), or ancient DNA analysis (to investigate kinship). Timeframes for post-excavation analyses will largely depend on the number and condition of burials recorded and as such no attempt will be made at present to indicate such.
The excavation will be carried out with a team consisting of the site director who is also an osteoarchaeologist, 1 no. supervisor, and 5 no. assistant archaeologists. The team will be supported by a GPS surveyor.
It is estimated that works will take seven weeks to complete. It is anticipated that the works will commence in August 2023, subject to MNH approval.
The site archive, and any finds, samples etc. will be kept in safe storage during the post-excavation stage. All necessary conservation will only be undertaken by a professional conservator.
The excavation archive shall be ordered, arranged, boxed and deposited with the statutory authorities in accordance with the standard and guidance as set out by CIfA (2014d).
A post-excavation assessment (PXA) report shall be produced within 8-weeks of the completion of the on-site works. This report shall include, as a minimum:
The PXA report shall be presented to the client and agent for approval prior to submission to MNH. Following approval of the PXA report a complete Fieldwork analysis report shall be produced. This shall include, as a minimum:
A digital copy of the final report shall be made available to MNH.
Should the results warrant it, a publication piece shall be prepared which will detail the excavation, highlighting any atypical finds/ features.
The project archive consists of the records relating to the archaeological work including written, drawn, photographic, digital survey, artefacts, and ecofacts. The archaeological archive shall be fully catalogued, indexed, cross-referenced and checked for errors/ omissions.
All digital data shall be stored on IAC’s internal server which can be accessed on and off-site by staff with permissions.
A retention/disposal strategy will pay due cognisance to the suitability of the data as a tool for future research. The excavation archive shall be ultimately deposited with the local museum service on the Isle of Man.
Brickley, M. and McKinley, J. (eds) 2004. Guidelines to the Standards for Recording Human Remains. IFA Paper No. 7.
Buckley, L., Murphy, E. and O’Donnabháin, B. 2004. The Treatment of Human Remains: Technical Paper for Archaeologists. Technical paper prepared by IAPA for Institute of Archaeologists of Ireland.
English Heritage 2017. Environmental Archaeology: A Guide to the Theory and Practice of Methods, from Sampling and Recovery, to post-Excavation. 2nd Edition. Historic England 2017. Guidance for best practice for treatment of human remains excavated from Christian burial grounds in England, 2nd Edition.
McClatchie, M. and O’Carroll, E. 2015. TII Palaeo-environmental Sampling Guidelines, Retrieval, analysis and reporting of plant macro-remains, wood, charcoal, insects and pollen from archaeological excavations (Revision 5). Dublin. TII Publications.
Monk, M. et al. 2007. Environmental Sampling: Guidelines for Archaeologists. Guidance document
prepared by the Environmental Subcommittee of the Institute of Archaeologists of Ireland. Watkinson, D. and Neal, V. 1998. First Aid for Finds, Revised Edition, RESCUE/UKIC.
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