Onshore installation works proper commenced in early June and progressed well; they comprised of 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 was completed at the end of October 15.
Ductile iron pipes were 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.
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.