Trenching Guidelines Minimum depth of cover for SERVICES

Trenching Guidelines Minimum depth of cover for SERVICES Public Road: 450 mm- 750 mm to meet main Public footpath: 450 mm Private: 375 mm- 450 to meet footpath Other plant Working farm/ fields: 1100 mm Minimum depth of cover for MAINS Min 250 mm clearance Public Roads and verges: 750 mm Public footpath: 600 mm Private: 600 mm Working farm: 1100 mm Gas pipe NB: ‘Other plant’ may be electricity cables, water pipes, other gas pipes etc. Min 250 mm clearance Before carrying out many excavations you must comply with safe digging practices and the Health and Safety documents HS (G) 47 entitled AVOIDING DANGER FROM UNDERGROUND SERVICES will provide the necessary information. This publication is available from H. M. S. O outlets Please note that you are responsible for ensuring that the excavation is safely guarded and does offer adequate protection to any person who may have access to your property. The excavation must adhere to the minimum depth requires as indicated in the schematic and be approximately 250 mm – 300 mm wide. For mains and services greater than 63 mm diameter, please refer to WWU staff for information for mains or services above 63 mm diameter. Maximum trench widths should be nominal size of main plus 250 mm when laying mains by open cut. Where trench support is required allowances should be made on the trench width and for excavations deeper than 1. 2 m or determined by site specific risk assessment, the trench width may be increased. The width of the trench must also allow for safe access and egress and for the use of necessary tools and equipment in the trench. Reference must be made to the Excavation Work Procedure for further information. The bottom of the excavation must be level and free from sharp granular materials which may damage the pipe. In poor ground containing sharp stones, it will be necessary to excavate a further 75 mm and this filled with fine material free from any sharp material. The reinstatement of the excavation should allow for a minimum of 75 mm of fine material (free from sharp objects and must be supplied by the customer) to totally surround the pipe. The consolidation of the backfill and final reinstatement including the safe removal of all surplus material is the responsibility of the customer. Other plant Minimum proximity requirements of mains running parallel with building lines. Operating pressure: Low pressure - 1 m Medium Pressure - 3 m Intermediate pressure - 6 m+