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T H A M E S V A L L E Y S E R V I C E S Trajan House, Mill Street, Osney, Oxford Archaeological Watching Brief by Andy Mundin Site Code: MSO04/35 (SP 5040 0595) Trajan House, Mill Street, Osney, Oxford An Archaeological Watching Brief For WE Black Ltd by Andrew Mundin Thames Valley Archaeological Services Ltd March 2010 Summary Site name: Trajan House, Mill Street, Osney, Oxford Grid reference: SP 5040 0595 Site activity: Watching Brief Date and duration of project: 16th December 2009 to 19th January 2010 Project manager: Joanna Pine Site supervisor: Tim Dawson, Andy Taylor and Andrew Mundin Site code: MSO04/35 Area of site: 0.24ha Summary of results: Two lift pits were observed during excavation. No other groundworks were observed due to foundation designs not requiring deep truncation. New ground beams mostly disturbed modern made ground and demolition deposits. A layer in each lift pit, at a depth of c.0.6m, contained 15th/16th century pottery, but also more modern finds. The lowest levels could not be clearly identified as being of Medieval date, as no finds were recovered. Location and reference of archive: The archive is presently held at Thames Valley Archaeological Services, Reading and will be deposited at Oxfordshire Museums Service in due course, with accession code OXCMS 2004.50. This report may be copied for bona fide research or planning purposes without the explicit permission of the copyright holder Report edited/checked by: Steve Ford 31.03.2010 Steve Preston 31.03.2010 i Thames Valley Archaeological Services Ltd, 47–49 De Beauvoir Road, Reading RG1 5NR Tel. (0118) 926 0552; Fax (0118) 926 0553; email [email protected]; website : www.tvas.co.uk Trajan House, Mill Street, Osney, Oxford An Archaeological Watching Brief by Andrew Mundin Report 04/35b Introduction This report documents the results of an archaeological watching brief carried out at Trajan House, Mill Street, Osney, Oxford (SP 5040 0595) (Fig. 1). The site was an irregular shaped plot of land of 0.24ha on the west side of Mill Street, directly north of the disused Osney Mill. The work was commissioned by Mr Tony Nolan of Ardent Ltd, Suite 2, Temple Court, 107 Oxford Road, Oxford, OX4 2ER, on behalf of WE Black Ltd, Hawridge Place, Hawridge, Bucks, HP5 2UG. Planning permission (70/20387/A) has been gained from Oxford City Council to alter the existing building, leaving initially only the core steelwork and concrete bases, modifying the exterior facades and building a new extension and associated lift access. As a consequence of the possibility of archaeological deposits being damaged or destroyed by groundworks, a programme of archaeological work had been requested. Initially, a field evaluation (Pine 2004) established the survival of archaeologically relevant levels on the site. After establishing a foundation plan to mitigate the disturbance of lower archaeology, a watching brief was required on the areas which might potentially disturb archaeological levels, namely; examination of lift pits and any other areas that may require deep excavation such as trenches for ground beams or crane bases. This is in accordance with the Department of the Environment’s Planning Policy Guidance, Archaeology and Planning (PPG16 1990), and the City Council’s policies on archaeology. This stage of the field investigation was carried out to a specification approved by Mr David Radford, Archaeological Officer for the City Council. The fieldwork was undertaken by Tim Dawson, Andy Taylor and Andrew Mundin, between 16th December 2009 and 19th January 2010. The site code is MSO 04/35, and is the second report to be produced for this site. The archive is presently held at Thames Valley Archaeological Services, Reading and will deposited with Oxfordshire County Museum Service in due course, with the accession code OXCMS.2004.50. Location, topography and geology The site is located to the west of Oxford city centre in Osney, on an irregularly-shaped parcel of land, bounded by a Mill race leading off the River Thames, and the course of the Thames itself, to the west. To the east is the southern end of Mill Street, and Osney Cemetery. The main Oxford- Birmingham railway runs to the east of the 1 cemetery. To the south is the abandoned Osney Mill. Osney in effect forms an island between branches of the Thames. At the time of the groundworks, the frame of the existing structure was all that remained and previous extensions had been demolished (Figs 2 and 3). Only a small amount of Tarmac carparking remained in the north half of the site. The highest point on the site is at 57.4m at its eastern entrance. The underlying geology, according to British Geological Survey, is alluvium, which is directly east and on the opposite side of the river from the Osney Island first (flood plain) terrace deposits (BGS 1982). Archaeological background An evaluation was undertaken on this site in 2004. Part of this report contained a desk-based component, of which its findings are summarized below. It was thought that the site had high potential for the presence of archaeological deposits. Prehistoric and Roman findspots had been noted from locations close to the River to the west and north, but of much greater significance was that the site was located close to or even within the grounds of the Augustinian priory of ‘Oseney’ Abbey. This was founded in AD1129 and raised to Abbey status in 1154 (VCH 1979). The Abbey may not have been affected early on by the Dissolution, in fact becoming the Cathedral of the new diocese of Oxford in 1542. However, the episcopate was transferred from the Abbey to Christchurch in 1546 (Spires, 1928). The construction of this new Cathedral may have reused stone from the Abbey: it has been noted that the bells were transferred there (Spires 1928, 96). Throughout the Civil War in the 17th century, more stone was taken from the Abbey to strengthen Royalist defences. Part of the Grade II Listed outbuildings at Osney Mill contain elements that may have reused Abbey timbers and structural elements. A likely layout has been hypothesized, by using mapping and documentary sources, and parts of the Abbey have been investigated archaeologically (Sharpe 1985). The present site would seem to be located on the site of the Great Court, which lead to the refectory and kitchens to the south, and almshouses to the north, the latter thought to lie to the rear of the properties on Barrett Lane. The excavation, to the south of the current site, found at least two phases of waterfront development and associated buildings, fishponds and the final abbey precinct wall. Evaluation of the proposal site (Pine 2004) showed that 13th-century features had survived in Trench 3 (Fig. 3). Most seemed to be overlaid by 16th-century demolition and made ground. Building stone (limestone) was identified within demolition deposits. It is thought from the mix of pottery recovered from various layers in the evaluation that the earliest construction of the Mill had disturbed Abbey deposits, with further disturbance in 2 the 19th century. There must also have been some disturbance from Trajan House’s original construction, as concrete bases and service cuts were noted within upper deposits. Objectives and methodology The purpose of the watching brief was to record any archaeological deposits affected by intrusive ground works. The foundation design for the new build component of the project took account of the findings of the evaluation. The foundations, which consisted of piles and groundbeams, were designed to be minimally invasive at depth to allow for preservation in-situ of the vast majority of archaeological deposits on the site. Components of the foundation design possibly of greater depth such as ground beams trenches and lift pits were to be observed as part of the archaeological mitigation reported here. If any archaeological significant deposits were encountered, these were to be archaeologically excavated down to just below the formation level of the foundations. Excavation of the lift pit trenches took place under archaeological supervision using a small 360º mechanical excavator, fitted with a bladed bucket. Results Before the programme of archaeological works commenced, all but the frame of Trajan House was demolished and piles for the new extension had been placed. Lift pits Two lift pits were observed during the watching brief. Both were excavated off the eastern side of the existing frame (Fig. 3). Lift pit 1 was excavated c.5m to the west of evaluation Trench 3, close to a 13th-century feature found in this Trench (Pine 2004). Lift pit 2 was excavated c.5m south west of evaluation Trench 1, close to an areas of medieval or later yard surface (Pine 2004) Lift Pit 1 took place in an area of carpark. Tarmac was removed over an area 2.7m square , and uncovered crushed concrete and orange gravel to a depth of 0.15m (Fig. 4). A layer of made ground was identified beneath this to a depth of 0.28m. This layer contained modern brick and tile and composed of a dark brown sandy silt (350). Beneath this another modern made ground, a dark grey/brown clayey silt, which contained sub-angular limestone pieces (351). This extended to a depth of 0.49m. To a depth of 0.62m, a brown sandy silt was noted, with small gravel and limestone pieces clustered at the top of the layer (352). This layer contained two 3 reasonably large sherds of Brill/Boarstall ware dated to between the middle of the 15th to the 16th-century and a small piece of glazed floor tile.