DWG Resins were approached by Sanctus Ltd to fill 1 x 2.5 metre Diameter - 60 metre long and 1 x 2.5 metre - 50 metre long subterranean redundant outfall pipes below a demolition / construction site in Kent.
The redevelopment of the former Richborough Power Station site at Pegwell Bay near Sandwich into the new Richborough Energy Park was controlled by a major electrical installation conglomerate and main client for the NEMO Link who along with Aecom and Sanctus were the main onsite contractors and engineers for the demolition and redevelopment of the site.
Due to the location and depth around 4 metres below 2 concrete slabs of a former building it was decided that they would take the less intrusive action and have DWG Resins fill the concrete lined water pipes below the former structure.
Due to the location and length of the pipes it was necessary for this to be deemed a confined space as it would only have one entrance with the same exit so the entire project had to be completed under the stringent rules and regulations regarding Confined Space entry and Traversing. This included have a emergency rescue team on site at all time whilst the Resins Industry team were within the pipes.
A safe and secure entry ramp was completed by Sanctus Ltd to allow entry down to the pipes 4 metres below the upper concrete slab to inspect and confirm structural integrity of both pipes. This had to been completed under the Confined space rules, all entry and gas monitoring logs were retained and copies supplied to Sanctus Ltd.
An exclusion zone was erected with barriers and signs displayed, confirming no unauthorised entry and confined space entry in progress, this was maintained until the project was completed to the clients satisfaction, the area was then handed back to Sanctus Ltd to
complete the redevelopment of the area.
The Resins Industry truck was parked on an elevated concrete slab around 75 metres away from the redundant pipes location and the material delivery hoses were run down to the foaming gun placed adjacent to the redundant pipes to be filled.
The Resins Industry specialist trained confined space team entered both pipes to erect the circular lightweight timber and plywood stop end walls, this was to retain the Bacel super lightweight foam, they also fitted the half circular intermediate bulkhead timber walls to half the height of the pipe to allow the material to build up within the confines of the stop end wall and the bulkhead walls sealing the pipe section by section. This was monitored visually and by camera throughout the filling process of each pipe and retained.
The confined space entry was completed with around 400mm of standing groundwater within the pipes, this was pushed by the advancing foam to the outer end (fill end) of the pipe and collected into a sump area before being pumped out to a holding area for purification by Sanctus Ltd.