FOUR KILOMETRES of sheet piling is being driven as part of a major sewer system project in south west Scotland. Glasgow contractor George Leslie is currently installing the piles for 12 cofferdams forming a new interceptor/tank sewer system in Ayr to link existing sewer outfalls. The firm is using a BSP HH1 5DA hydraulic hammer to drive the sheet piles for the 50 week, £0.7M contract for the West of Scotland Water Authority.
Four of the cofferdams are circular, up to 9.5m in diameter, and the rest are rectangular, 10m by 8m. Each is joined together by pipe jack tunnels formed by Iseki Unclemole boring machines. These are between 2,845mm in diameter and 1,700m long and 1,120mm in diameter and 200m long. The 10m and 14m long sheet piles will support the 1.8m diameter open cut sewer up to 8.5m deep. The piles are being driven through sand, gravel and silts and into glacial till.
BSP says the hammer is capable of driving single sheet piles and concrete and H beams and because of its low weight, 3.9t, combined with high impact energy means it will fit on small capacity cranes.