York Historic Environment Record

Excavation and recording of four lightweight windowless dynamic rig drilled boreholes, designated as water monitoring points, using data gathering as part of a six month monitoring programme for analysis of water quality and hydrology. The windowless sample boreholes were notionally excavated to a depth of 10m BGL, however this was curtailed in WS01 when the top of undisturbed natural deposits were reached at 8m BGL, and in WS02 when an obstruction at 8m BGL halted excavations. Based on the results from the geochemical sampling exercise and groundwater monitoring program, the sub-surface deposits below 2.4 m BGL remain waterlogged, anoxic and highly reducing. The primary influences on the water levels are from natural groundwater flow through the site as well as rainwater, with levels closest to the river Foss almost static (due to the canalization of the Foss impeding water movement) whilst greater fluctuations are observed in the deposits furthest away from the river Foss.