Infilling our Tunnel at our Betchworth Quarry
Work has just finished on infilling our tunnel at our Betchworth site.
The Tunnel was used for 9 years and enabled access into the Common Field as an extension to the Betchworth Quarry. The additional field released over 700,000 tonnes of building sand and took over 50,000 lorry loads of inert waste to backfill the void to original levels.
The infilling of the tunnel had to be completed using pumped concrete, and the work was again completed by our “friends” The Gallagher Group from Maidstone in Kent.
The final placing of the soils on the Common Field is currently underway.
History of the Tunnel
In November 2011, The Gallagher Group from Maidstone in Kent, constructed a new accessway to join the two parts of J & J Franks’ Betchworth Quarry. This was fundamental to us, as it allowed us to continue operating our quarry activities and provided continued employment for our skilled work force.
The existing sand quarry with permitted landfill was located on both sides of the Old Reigate Road in Betchworth, Surrey
Gallagher was awarded the contract for the construction of a cut and cover tunnel, and works were undertaken over a two month period. A diversion was set up to allow pedestrians and motorists to access the villages either side of the accessway.
The excavation was carried out in two stages. The first involved excavating around the existing statutory services (BT, UKPN – LV + HV and gas) which added to the challenges of the job. Ladder beams were used to span over the 16.00m excavation, with some services supported in split ducts and ratchet straps and the BT ducts using trunking and threaded rods. The existing water main was cut out and capped by the water company prior to the works starting. The ground was excavated to formation level and concrete base cast. The precast units were lifted into position by ABM Precast under a contract lift (the crane mat was previously prepared by Gallagher Ltd). The reinforcement and insitu concrete slab was prepared and concreted followed by backfilling to the underside of the road. Water proofing and mastic works to inside/outside of units were undertaken as the backfill was carried out. The sub-base stone, kerbing and tarmac to the road were laid along with topsoil works to the quarry banks and the erection of fencing. Finally, a tarmac strip was run through the tunnel.
