# 1995 Edinburgh
Trenchless contractors throughout the world sometimes feel they have an uphill job trying to gain acceptance for non-disruptive technology. A major obstacle is that trenches, however dangerous and however much traflic chaos they cause, are cheaper. However with the implementation of the new Road and Street Works Act together with the advent of more novel nodig techniques in conjunction with more flexible and more cost effective materials this is beginning to change. This paper details two large diameter water mains rehabilitation projects where no-dig technology and polyethylene pipelines are utilised. Subline is the technique which was used by Essex Water to rehabilitate a twin 1 km cast iron pipeline using 495mm and 595mm SDR 26 HPPE to re-line the failing 20" and 24" cast iron mains in Southend. Thames Water used 567m of lOOOmm HPPE to slipline an existing 42" steel pipe which suffered from corrosion and leakage.