An archaeologist was generally present on site during the course of significant groundwork which had the potential to reveal archaeological remains, although on occasion, work took place without the archaeologist's knowledge. This was despite repeated attempts of contact to ascertain the work schedule on site. Initial excavations began with a series of trial pits excavated around each of the 12 Gas Holder 2 stanchions. These were excavated down to the stone footplates at the base of the iron stanchions in order to determine the condition and stability of the fixtures. Following the trial pits, a ground reduction of the surrounding area of Gas Holder 2 occurred to allow for the reinforcement piling ring to be constructed. This ground reduction took place in two stages. The first stage was a general reduction which exposed a series of made-ground deposits, structural foundations and pipe systems. This covered an area measuring roughly 62m by 68m. Before the second stage took place for the piling ring, the area surrounding Gas Holder 2 was levelled completely between 5.07m and 5.77m AOD. All remains were removed at that level. The second stage was a focused reduction on the area needed for the piling ring which exposed further made-ground deposits and earlier structural foundations and walls. The area of the second stage was circular and had a diameter of roughly 55m. In between the first and second stages of the ground reduction, a detailed recording of the Gas Holder 2 retort wall took place through the use of photogrammetry modelling. This took place in June 2020 and fully recorded the external surface of the wall. Throughout the course of the groundworks, the retort wall was not damaged by any machining taking place. Following the ground reductions and the construction of the piling, a further area to the west of Gas Holder 2 and on the exterior of the piling ring excavations, was excavated for the Phase 1 basement works. These Phase 1 basement works also occurred in two main stages. The first stage covered an area measuring roughly 25m by 15m. Part of the area to the immediate west and south-west had already been excavated away, and a new access ramp constructed. The first stage of the Phase 1 basement area comprised of initial ground reductions before the necessary depth was eventually reached. The second stage covered an area measuring roughly 11m by 20m and was excavated down to the required level of construction, which was roughly 1.10m AOD. The full excavation works for the second stage of the Phase 1 basement works were reduced without being monitored, and so only partial records could be accurately positioned and located alongside the piling ring excavations, due to the client failing to inform JMHS when these works were commencing. Where archaeological horizons were encountered they were cleaned by hand (where possible) and excavated appropriately. Due to the highly contaminated nature of the site (Blue Billy, asbestos and benzene), these practices were not always appropriate or safe to undertake. These issues precluded anything above basic recording of the contexts revealed before the area needed to be made safe (generally through backfill). Standard John Moore Heritage Services techniques were employed throughout, involving the completion of a written record for each deposit encountered, with scale plans and section drawings compiled where appropriate. A photographic record was also produced. The resultant spoil from the works was visually scanned, especially for finds relating to the use of Gas Holder 2. The archaeological watching brief aimed to identify significant archaeological remains pertaining to the previous use of the site area, as well as to further establish significant evidence related to Gas Holder 2.
Christopher Whitehead (Sat,) studied this question.