GoJ - 11814 – Bonne Nuit Foul Sewer Extension and Rising Main

Description

Bonne Nuit Sewage Treatment Works (STW) is located on Jersey’s north coast, adjoining the harbour in Bonne Nuit Bay. Bonne Nuit STW is approaching the end of its design life of 20 years. It is therefore necessary to carry out upgrade works to ensure that management of sewage is maintained at the site. Following review, it has been determined that replacement of the STW with a new pumping station to allow flows to be transferred to Bellozanne STW is the preferred cost-effective solution. It is therefore proposed that a new sewage pumping station (SPS) will be constructed at Bonne Nuit STW, together with a new rising main, which will transfer all sewage flows into the existing sewerage system connected to Bellozanne STW. It is also proposed to construct a new foul gravity sewer along the same route as the new rising main to facilitate the future connection to the SPS of properties currently served by septic tanks. There is a length of unused 90mm OD HDPE rising main from Bonne Nuit STW which terminates to the east of Bonne Nuit Apartments, with a further short section of unused 90mm OD HDPE installed in the road adjoining Bonne Nuit Apartments, which terminates near to ‘Fresh Springs’ in Charrières de Bonne Nuit. It is proposed that the existing main will be extended from the termination point at Fresh Springs by approximately 915m to discharge into a new manhole on the existing gravity sewerage system in La Rue de La Porte, near the village of St John. This will enable the transfer of flows from the new pumping station, once completed. It is uncertain whether a section of length approximately 70m of the unused 90mm OD HDPE rising main has been constructed. The existence of this section of the main shall be confirmed as part of the works. If the section is found not to exist, it shall be constructed under the Contract. It shall be assumed that this section of main does not exist and a new 90mm OD HDPE is required to be installed along this length. The new gravity foul sewer will follow approximately the same route as the new rising main and will extend from a starting point in La Rue de La Porte south of the junction with La Rue d ‘Eglise to connect to an existing manhole near to ‘Fresh Springs’ in Charrières de Bonne Nuit. This contract is for construction of the new rising main and foul sewer, including construction of manholes on the sewer and ‘blind’ connections to the sewer for possible future connections. Keywords: civils