T(o)sustain development of our first new town,Tsuen Wan,drainage improvement works were carried out in Tsuen Wan and its adjacent district Kwai Chung in order to alleviate flooding impact to them.One of the major works of the drainage improvement was to lay a large diameter stormwater pipe across heavily trafficked Texaco Road which is a strategic road and houses numerous underground utilities such as gas pipes,storm and foul drains,power cables and pressurized water mains including a freshwater trunk main and an asbestos cement saltwater main.To carry out the drainage improvement works under the above site constraints while to ensure a safe and healthy working environment as well as to minimize disturbance to the residents in the neighborhood,we devised an innovative grouted jacket as a major protection measure to existing water mains for laying of stormwater pipe by trenchless construction.The grouted jacket could overcome the inadequacy of soil arching strength due to shallow soil cover,eliminate the risk of flooding the workers inside the pipe bore in case of bursting of water main,and confine the pipe jacking activities within the grouted jacket.To construct the grouted jacket,ODEX drilling method was adopted with a revised Tube-A-Manchette(TAM)grouting method.Successful completion of the grouted jacket and pipe jacking for the drainage improvement works were achieved.