Site Event/Activity record ECH6898 - Northgate Redevelopment, Phase 1, ‘Grassy Knoll’ and Bus Station, Chester: Archaeological Evaluation and Watching Brief Report

In 2019, an archaeological evaluation and watching brief were undertaken on the ‘Grassy Knoll’ (also known as the ‘pocket park’), the former bus station, and Hunter’s Walk, on the south side of Hunter Street, as part of the Phase 1 redevelopment of Chester Northgate. The area lies within Chester’s legally protected Area of Archaeological Importance (AAI), at the heart of the Roman legionary fortress and within the medieval walls. In total, eight evaluation trenches (Trenches E-H and J-L) were excavated, to determine the depth of the uppermost significant archaeological deposits and to identify any areas where significant archaeology may have been damaged or destroyed. The purpose of this was to determine the potential impact, on significant archaeological remains, of proposed structural features in this area, such as pile caps and lift pits. Eight small test-pits (Trenches i-viii), excavated to assess the condition of wall foundations at the rear of existing buildings fronting Northgate Street, were also monitored. The 'archaeological plane' (top of significant deposits) was identified in four of the evaluation trenches on the ‘Grassy Knoll’ (Trenches D, E, F and H). This comprised the upper surface of a dark soil containing varying quantities of stone rubble which, in places, overlay deposits of sandstone rubble probably resulting from the demolition/decay of buildings in the Roman legionary fortress. Stratigraphically, the overlying dark soil appears to date to the late Roman and/or the earlier post-Roman period, though the few finds recovered were largely Roman. In Trench H, both the dark soil and the rubble were recorded in section only, having been removed over the area investigated by extensive disturbance associated with the construction, during the nineteenth century, of buildings on the north side of Princess Street. There, the stratigraphically earliest deposit recorded was a buried soil, lying directly above the natural bedrock, which is thought to represent the ground surface in the early Roman period. This deposit was also recorded further to the east, in Trench G, where late post-medieval disturbance adjacent to Princess Street had also removed all later archaeological remains. Further east, in the former bus station, where most of the latest archaeological remains had been excavated and removed in the late 1970s/early 1980s, only the modern surfacing material was removed in Trenches J and K, and nothing of archaeological significance was exposed at this shallow depth. In Trench L, a fragment of sandstone walling, possibly representing two construction phases, was recorded. Evidence obtained from the earlier archaeological work in this area, and from more recent investigations at the Story House, north of Hunter Street, suggests that it may form part of a large courtyard building of uncertain function, situated in the central range of the legionary fortress. Overlying this was a dark soil deposit, reminiscent of that overlying the late Roman demolition rubble on the ‘Grassy Knoll’. Test-pits excavated to the rear of the buildings fronting Northgate Street did not reach a depth sufficient to expose archaeologically significant remains, if present. Over most of the areas investigated, the archaeological plane (where recorded) was overlain by a thick build-up of dark soils that, from the associated finds, appear to have accumulated during the medieval and post medieval periods. These were in turn overlain by modern topsoils and other recent deposits. On the ‘Grassy Knoll’, a considerable depth of modern material was deposited as a result of landscaping during the establishment of the ‘pocket park’. In the former bus station, the archaeological plane was sealed by a soil containing a few sherds of medieval pottery. This was itself overlain by a layer of crushed limestone forming the sub-base for the modern reinforced concrete surface. (1) Post excavation analysis for the full scheme of mitigation undertaken as part of the Phase 1 re-development. (2)