SOJ-T-DFI-Fort Regent Cavern Washdown - Civil Works

Tender description

The Fort Regent Cavern (‘the Cavern’) acts as a detention/balancing tank, receiving unscreened overflows of sewage/stormwater (possibly contaminated with seawater) at times of high (storm) flows in Jersey’s main sewerage system. The Cavern facility is constructed within the rock of the hillside under Fort Regent. Due to a lack of any automated mixing or cleaning facilities, the Cavern tank suffers from significant deposition of sewage solids and grit on the Main Tank floor. These deposits have to be periodically removed manually and treated off site prior to disposal. Currently this operation is carried out annually. The operation is hazardous due to: • nature of the deposits; • restricted access; • steep slopes present in the tank; and, • the tank being a confined space with associated risks from gases, low oxygen, poor access etc. To remedy this situation, Growth, Housing and Environment have decided to provide mixing and carry out other modifications as necessary in order to keep the solids in the Main Tank and sump in suspension and to ensure that they are removed as far as practicable by the sewage return pumps during normal tank emptying, thus minimising the deposition of solids and manual cleaning requirements. The modifications also include changes to the benching in the main Cavern pump sump and modifications to the existing inlet pipe discharge arrangements. Additional refurbishment works are also required to be completed. The scheme will be delivered in a number of separate contracts including this contract for the Main Civil Works; The Works to be carried out under this Contract include design and construction of the following: • Modifications to the existing pump sump to improve solids removal including: • Civil modifications to the Main Tank floor to install new electrical cable ducts (for new mixer cables installed by others). • Provide temporary lighting, access, lifting and other facilities necessary for completion of the Works. • Provide site accommodation and facilities including facilities for the Mixing System supplier. • A structural survey of the condition of the existing access stairs, ladder and walkways to be carried out by a suitably qualified Structural Engineer, including the provision of any temporary access, lighting and cleaning necessary to complete the survey. • This Contract is for the design, supply and construction/installation of the above works. Keywords: civils, refurbishment, facilities