| Abstract: |
An archaeological watching brief was undertaken by ISCA Archaeology at the site of a proposed small office building at Sideshore, Exmouth, Devon.
A total of five screw tests were undertaken.These tests were also undertaken to assess the below ground deposits for any obstructions, possibly relating to former structural elements of the 19th century fort. Three screw tests (1-3) were undertaken using a 35mm screw, sunk to a depth of 1m below the present ground level, and a further two screws (4-5), with a 76mm diameter, were sunk to 2.5m depth. A total of five trial screw tests were undertaken to assess the soil conditions and the feasibility of using screw piles for the footing for any potential future structure. These tests were also undertaken to assess the below ground deposits for any obstructions, possibly relating to former structural elements of the 19th century fort. Three screw tests (1-3) were undertaken using a 35mm screw, sunk to a depth of 1m below the present ground level, and a further two screws (4-5), with a 76mm diameter, were sunk to 2.5m depth.
All five of the screw tests indicated the presence of a 50mm thick tarmac surface associated with the former road/car park at a depth of 550-600mm below the present ground level. The tarmac layer was laid on a 100mm thick layer of poured concrete. Sealing the tarmac was a 300mm thick layer of re-deposited silty clay, which in turn was sealed by a 250mm thick layer of grassed loose clay and sand.
To ascertain the nature of the deeper soil deposits, and their structural integrity below the concrete and tarmac layers, a c. 300m by 400m hole was hand-dug through the overlying soils to the top of the tarmac layer. A hand-held Jackhammer/breaker was used to create a small hole through the tarmac and concrete layers, through which the two deeper screws (4-5) could be sunk. The two deeper screws encountered no further obstructions, the deposit below the concrete layer consisting solely of compacted sand.
No evidence of any existing remains (masonry or other structural remains) of the fort were noted below the tarmac and concrete layer, though as this screw testing only targeted a small percentage area, remains associated with the fort may be present elsewhere. If the proposed construction of the new office building proceeds and this type of screw piling is used any below ground obstructions will be removed in their immediate location by using a breaker. |
