Acle Bridge, Upton with Fishley, Norfolk. Window Sample Borehole Investigation

Three window sample boreholes were put down along a single N-S transect perpendicular to the present course of the River Bure, flowing 34m to the north. Two of the window samples were located within the area of the proposed new western marina basin, while the third was located to its south but within the wider proposed development boundary. Cores were recovered using a tracked (Terrier) percussion sampling rig with samples retained within sleeved 1m sections. Boreholes were discontinued on encountering sample recovery failure, which occurred between 4.6m and 6m below ground level. The core samples were removed from site unopened allowing extrusion and detailed recording under laboratory conditions, including sub-sampling for palaeoenvironmental analysis and radiocarbon dating where appropriate. Sample sleeves were first split down their centreline, providing a section through each of the recovered cores. One half was then cleaned back with a spatula and sedimentary boundaries identified and measured. The revealed lithostratigraphy was described using standard procedures for the recording of unconsolidated and organic sediments, noting physical properties, composition, consistency, sedimentary boundaries and inclusions. A digital photographic record was made of each section. The revealed sequence of Upper Clay, extending down to -6.37m OD (and continuing) is typical of the upper Breydon Formation marshland sequence, where Upper Clay deposits can reach over 6 metres in thickness. The uppermost 1.4 m of the deposit shows signs of weathering as a result of the artificially lowering of the water table and subsequent compaction. The sequence at the Site was found to contain no organic rich deposits or organic materials worthy of further palaeoenvironmental assessment. No material suitable for radiocarbon dating was encountered during the evaluation. The location of the Site is sufficiently distant from the marshland edge to the east to contain the discontinuous Upper Peat that outcrops along the marshland fringe. The Middle Peat of the Braydon sequence was not encountered during the evaluation and either sits beyond the depth of the present evaluation, or local erosion by transformational channels has effectively removed this part of the succession. Either way, the proposed creation of an extended mooring basin and associated infrastructure would not impact these deposits, if present.