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!l t t t Ll necessary for various related tasks) must be on the job site at the beginning work. A competent and experienced supervisory representing the contractor that is thoroughly familiar with the equipment and type of work to be performed, must be in direct charge and control of the operation at all times. In all cases the supervisor must be continually present at the job site during the actual crossing operation. PART 5 - INSTALLATION 5.01 GENERAL 1 07/03 A. Erection or Installation of Appropriate Safety and Warning Devices - Erection or installation of appropriate safety and warning devices shall be completed prior to beginning work. B. Subsurface Soil and Drainage Investigation - In general, the greatest influences on the success or failure of an underground crossing are the existing subsurface soil and water conditions. To correctly plan individual crossing procedures such as dewatering, use of cutting heads, positioning of auger within the casing and to accurately locate potential problem areas, subsurface investigation must be made by the permittee or his contractor. C. Dewatering - Evacuation of ground and surface water from jacking and receiving pits and from path of proposed crossing. Where the ground water level is above the invert of the proposed crossing, or above the floor level of the jacking pits, dewatering is necessary to reduce the water level to below the jacking pit floors and the invert of the proposed crossing, and must be designed, installed and in operation prior to beginning the crossing as follows: 1) Except where rock is present throughout the length of the bore and no likelihood of sand pockets exists. 2) Where the existing ground water level and particular soil type involved indicates that excessive flowback of spoil material as the jacking progresses is likely. Dewatering shall not be necessary where remote - powered hydraulic equipment is used to make the crossing underwater. 16200 -8 03- 1438.A