Chelmsford Borough Council awarded Owls Hall Environmental Limited contract for the design and installation of a pumped sewerage system to connect Hylands House and its associated buildings and facilities to the public and foul sewer. The system design and installation included all materials and workmanship shall be in accordance with the Sewers for Adoption 6th Edition published by the WRC.
At the start of the project survey work, was conducted to establish relative levels between the existing public sewer connection point and the existing inlets to the treatment plants or cesspools. For the purposes of establishing peak flows to enable the design of pump rates etc, usage figures for the House and the Visitor Centre were taken into consideration. For the design of the new pumping unit to serve this facility, a figure of approximately 200 users per day was assumed.
The main works included installation of pumping stations and necessary internal pipework, valves, guiderails, lifting chains with access covers at ground level to enable removal of pumps for maintenance. Rising mains were constructed from MDPE pipework with air release valves at any high points to avoid siphoning of the main and at the same washout chamber was installed with a suitable tee piece with valve and bauer connection at the low points in the valley to allow draw-off of sewage from the main for periodic cleansing. An air release valve was also installed close to the pumping station to avoid the risk of ‘siphoning’ of the pumping main. Each site included two identical pumps that operated on a duty standby arrangement with auto switchover. All plant shall be designed to minimise operational input. Further, the project also included de-commissioning the existing redundant plants for making safe.
The project was successfully completed with zero accidents by adopting lean management technique and adopting stringent health and safety standards on site.
