Water Main Upgrade for Wiltshire College Lackham
The college conducted an open tender to find and appoint a contractor to replace the mains water supply pipe feeding Lackham Agricutural College in Wiltshire. As well as supplying the campus the project included extending the new distribution system to two working farms.
- To map and identify the run of the existing water supply pipe along with all points of use, sub-meters and isolation valves.
- Propose alternative best routes, avoiding hard surfaces where possible, for the new water pipe
- Recommend additional isolation and configuration to meet current best practice, regulation and College needs
- Replace the existing water pipe and all connections, installing manholes and isolation valves as recommended/identified
- All works to be executed without disruption to College and Farm activity
Pipefix were the successful bidder and proposed a new 180mm High Density Polyethelene (HDPE) water main using electro fusion welded joints with estimated time on site of 24 working days.
This method involves laying the pipes above ground within the working areas along the proposed pipe line; electro-fusing the pipe work to assemble the pipe line; pressure testing the pipe ‘strings’ to verify the jointing and then placing the pipe in a trench.
The lead excavator, in this case a 13 ton slew, digs the line of trench, stripping topsoils and placing them in one wind row. Then excavates sub-soils and places them in a second wind row. The main-laying gang then place the welded pipe strings within the trench.
A second excavator, in this case an 8 ton slew, backfills the line of trench with selected as-dug materials once the main has been laid, reinstating topsoils to the line of pipe. This minimises the length of time that the trench is open and speeds the reinstatement of the grassland post-works. Some sections of the pipe line are left open in places pending the final testing and disinfection of the pipes.
Once the pipe line has been laid it is swabbed (debris removed from within pipe), pressure-tested and disinfected. Once all tests have passed the main is connected up and then the various services transferred on to the new main before the the old pipeline is capped off.
Upon completion of the works a drawing was produced showing the new pipeline and all the services, recording location, depth and material. Additionally all the existing services to the troughs around the site were traced and their location recorded on the new schematic to provide the customer with a complete drawing of the system.
Client: Wiltshire College Lackham
Works: Upgrade 9km of supply to 180mm HDPE