Archaeological Investigations at Northfleet
Water Treatment Works

Mick Diack, August 2007

Canterbury Archaeological Trust has recently completed a programme of archaeological work on behalf of 4 Delivery Limited, at Southern Water’s treatment works located off Thames Way, Northfleet, Kent.

The area is rich in archaeological remains spanning almost the whole period of human occupation of the British Isles; with numerous flint tools and an early hominid skull from nearby Swanscombe and Northfleet Roman Villa being of particular note. There have also been numerous archaeological discoveries close by during the Channel Tunnel Rail Link and the South Thames-side development projects. A Scheduled Ancient Monument, consisting of a Neolithic settlement incompletely excavated in 1938–9 and in 1960 is located within the south-western corner of the plant.

The underlying geology of the Ebbsfleet valley is Upper Chalk, overlain by a complex sequence of deposits laid down during the last Ice Age (Pleistocene). The Ebbsfleet is a small stream that emerges at Springhead and flows northwards to the Thames. The water treatment works lies close to the existing Ebbsfleet which flows north–south immediately to the west of the site. To the north of the site is the now dried up Brook Vale tributary.

The archaeological works included a watching brief on exploratory boreholes and on the construction of the primary settlement tank (PST). Evaluation trenches were cut to investigate the inlet works, the aeration lane and the pumping station. Of these the PST area was significant and revealed a thick layer of peat containing worked flint of Neolithic date and rich in preserved plant remains as well as seeds, hazelnuts etc.

The principal area of archaeological work has been in the final settlement tank (FST) area (Plate 1) where a number of archaeological features were excavated and where a series of deep trenches were cut to record the sequence of deposits dating from the last Ice Age onwards (Plate 2). Layers of sediments from the river valley were noted containing worked and burnt flint indicating considerable human activity in the vicinity from at least the Late Neolithic and Early Bronze Age (Plate 3 & 4). These waterborne deposits were cut by a ditch of probable agricultural function. The ditch was in turn cut by a roughly 12m wide square feature of uncertain function filled with a sequence of peat layers. These contained burnt and worked flint, animal bone, including a horse (Plate 5) and were very rich in environmental remains (Plate 6). Sealing these deposits were layers of colluvium (material that has washed downhill) containing large quantities of worked flint, an indication that a substantial prehistoric site had existed up the slope to the south. Much of the principal area of this site had therefore been eroded away and the site as excavated here was only part of a much larger settlement. The quantity of worked flint recovered from the site was extremely large however and will significantly contribute to our knowledge of the prehistory of the area.

Much of the information about the site will come from the examination of soil samples which will provide evidence about the ancient environment. This examination will look for preserved plant remains, seeds, pollen, snails and small animal and fish bones which will tell us whether the area was wet or dry, if the water was salt or fresh and, if dry land, if it was open or woodland. These remains will also tell us if the land was being used for growing crops. Further information will come from scientific dating, both radiocarbon from organic remains like charcoal, seeds and animal bone and luminescence (OSL) that dates particles of quartz from the sequence of post Ice Age deposits.

Canterbury Archaeological Trust would like to thank 4 Delivery Limited, who funded the excavation and who have agreed to fund the post excavation programme.