Geomarine are moving into the final phase of the £1.8M onshore installation of the Belle Greve outfall replacement project.  The headline works where awarded to international dredging and offshore contractors Van Oord UK Ltd in January 2015 with Geomarine as their onshore partner.

An intense 3 month design and procurement period followed prior to Geomarine starting enabling works in early May.

Onshore installation works proper commenced in early June and have progressed well; they comprise the installation of a new 700mm diameter Long Sea Outfall (LSO), a 900mm diameter Short Sea Outfall (SSO) and the construction of two major reinforced concrete valve chambers. The busy programme is due to complete at the end of October.

Ductile iron pipes have been laid in open cut excavations to a new valve chamber located on the compound access road. “The phased work plan went really well, considering how congested the area is with existing services. Having to remove the existing [600mm diameter] SSO and valve chamber whilst maintain constant access to the facility made the task very complicated. Great care was given to the welfare of local residents and stakeholders.” says Tim Kaines, Site Manager.

The 6 meter deep “chamber 4”, located on the foreshore just behind the sea wall, will house two vertical pipe stacks for both the LSO and SSO, pumps and a pressure relief valve. The chamber will also align with the incoming marine works installed by Van Oord which provides a unique set of engineering challenges for the team.

Once again Geomarine have employed numerous civil engineering skills on this project; Group Company Granite le Pelley will also be on site cladding chamber 4 with local granite.

Last but not least Project Director Gary Stevenson and his team have to deal with traffic management on Guernsey’s main coast road as the two pipes are taken through a major road crossing over an intense three week period.

The outfall replacement project is the final one of five phases of work at Belle Greve. Commencing in 2008, they will be completed by the end of 2015. At a total cost of around £35m, client Guernsey Water will deliver an effective and appropriate wastewater disposal solution for the island.