Event/Activity EPM218 - Archaeological Watching Brief at the Mary Rose New Museum Portsmouth Historic Dockyard

A watching brief was carried out by Pre-Construct Archaeology Ltd in 2010 on the initial phase of groundworks for the construction of a new Mary Rose Museum in Portsmouth Historic Dockyard. The main watching brief took place between the 4th January and the 9th April 2010, with a further watching brief on a drainage trench undertaken on the 21st and 22nd of July 2010. The development work took place in and around the Scheduled Ancient Monument Dry Dock No 3 (completed in 1803), and a programme of archaeological supervision and detailed recording before and during the groundworks was required as a condition of Scheduled Monument Consent. The main aim of the watching brief was to record any archaeological remains exposed during the groundworks and further knowledge of the methods used in the construction of the dry dock. The watching brief involved monitoring the excavation of observation pits, the grubbing out of 20th century building foundations, the removal of dockside furniture, and the excavation of a service trench. Archaeological trenches were also excavated within the footprint of the new building. All of the principle archaeological features were located and levelled using GPS and Total Station, and a comprehensive photographic record was made using 35mm colour slide and black and white film, together with high resolution digital photography. Four observation pits were excavated in/around Dry Dock 3 in order to clear the ground where the main pile caps for the new museum were to be placed. The pits were located on the North West side of the outer dock wall (8.16m east-west x 5.42m north-south x 3.40m deep), and in the North East (3.79m east-west x 3.79m north-south x maximum 4.50m deep), South West (5.80m east-west x 5m north-south x 2.50m deep) and South East (8.5m east-west x 6.6m north-south x 3.5m deep) corners of the dock. The excavation of two of the pits (those in the North East and South East corners), involved the removal of stone built chutes that had been used as timber slides. Each stone was numbered, three dimensionally surveyed by Total Station, catalogued and photographed. With the agreement of English Heritage the stones which presented a 'seen face' were then stored so that they could be reassembled in the future. Monitoring took place on the grubbing out of foundations belonging to a number of 20th century buildings on the north and south side of Dry Dock No 3 which had been demolished prior to the commencement of the work. A stone built dockside feature partially revealed during the removal of foundations at the North West end of the dock was recorded and backfilled with sand. The removal of 18 items of dock-side furniture, mainly consisting of bollards, on the North and South side of Dry Dock No. 3 and South side of Dry Dock No. 4 was monitored and recorded. Scale drawings were made of a selection of bollards, and a photographic record taken after removal. The items were then stored for future use within the landscaping surrounding the new museum. Four archaeological trenches were excavated in a rectangular grid on the north side of Dry Dock No 3, within the footprint of the ground beams to support the new building. The trenches measured 29.42m east-west x 0.60m north-south x 0.70m deep, 29.70m east-west x 0.60m north-south x 0.60m deep, 8.10m north-south x 0.60m east-west x 0.50m deep, and 6.24m north-south x 0.60m east-west x 0.60m deep. The excavation of a service trench to the south of Dry Dock No 3 was monitored in July 2010. This measured 24.50m long x 0.50m wide x 0.60m deep at the southern end and 0.80m deep at the northern end. The concrete bases of extensive basements revealed beneath the Trafalgar Building during the grubbing out of the buildings foundations were broken up but not removed. The voids were backfilled to ground level with crush material. No further investigation within the footprint of this building was undertaken as the depth and extent of the cellars would have severely impacted on the survival of any archaeological deposits. Accession No: 2022/97 (previously numbered 2008/323)