Plate 4
Field Archaeology Specialists
The evaluation trench was positioned in order to test the hypothesis that buildings shown on the 1850 auction map (National Gas Archive, Plate 4) reused or retained some element, in plan, of the medieval Cordwainer's Hall. The 1850 auction map was digitised and then superimposed onto modern OS Superplan data. The trench was deliberately positioned in order to contact the southeastern elevation, being the rear wall of the range of buildings.
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Plate 4 |
A single evaluation trench, Intervention 2, was excavated. It was located in the car park of Barnitts' warehouse (Fig.2 JPEG/DWF) and measured 4.00m x 2.00m. Prior to excavation, the location of known services and any additional services identified during a walkover survey using a cable avoidance tool, were marked out on the ground. The location of the trench was then laid out using a total station theodolite and the tarmac surface was cut using a floor saw. The trench was then excavated using a back-acting JCB wheeled excavator fitted with a 1.20m wide, toothless ditching bucket under strict archaeological
supervision. All overburden and modern deposits were excavated until a redundant utility cable and grey-water drain were contacted. Excavation below this point was carried out by hand to a depth of no greater than 1.50m below current ground level. Since excavation contacted below-ground structures belonging to the nineteenth century gasworks, precautions were taken when exposing potentially contaminated strata. Further excavation of the structure defined during excavation was undertaken by mechanical excavator after full recording had taken place.
Written, drawn and photographic records were made of archaeological deposits. All survey was undertaken using the Ordnance Survey grid; all alignments expressed refer to this grid and all heights are expressed in metres above ordnance datum (AOD).
The recording system followed Field Research Procedure (Carver 1990), the standard operating system employed by Field Archaeology Specialists. A single index was created for contexts starting at C1000 and for features starting at F1. A checklist of records created during excavation, which form the content of the archive, is given below (Appendix A).
Due to the potential for contamination at the site, a risk assessment was undertaken prior to excavation and procedures for dealing with contamination were defined. It was agreed before the onset of groundworks that the archaeological team would only work within trenches if they were clear of obvious contamination, and that any work within such trenches would be carried out with the excavators wearing suitable protective personal equipment (PPE). Disposable overalls, steel toe-capped Wellington boots, kevlar and disposable gloves were to be worn to minimise skin contact with the soil as well as face masks or powered respirators to avoid the effect of any accumulative gases. The immediate area of the trench was fenced off with Heras fencing and the area inside was to be considered a dirty area and only to be entered wearing all the relevant PPE (Plate 5). A portable unit was provided for hand washing.
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Plate 5. |
