Perrin, N.D. 1971 Wellington urban motorway : amended geology of north portals, Terrace 1972 tunnels. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 123 30 p.
Abstract: Colluvium, clays and silts are present to a depth of approx. 15 feet on the floor of the gully. Old stream channels or slip scars filled by solifluxion deposits are present along the proposed western retaining wall. The Terrace Fault is roughly parallel to the eastern retaining wall, possibly intersecting it near Everton Terrace. Poor quality rock is likely to be encountered in the fault zone. Adversely dipping shear planes occur in the hard bedrock of the western side of the gully, but bedding dips mainly favorably at 45 degrees to the west. The slope below Kelburn Park has remained relatively unchanged for a considerable period, and no very recent slips have occurred. Design to the pre-construction factor of safety should therefore be adequate. Rock condition in the proposed anchor drives is uncertain, and further exploratory work is necessary, particularly for the eastern anchor drive. (auth)