North Yorkshire County Council had a problem where an abandoned shaft which had been used as a landfill site had opened up and the old rubbish mound was progressively collapsing into the hole presenting grave danger to walkers and animals (some of which had been lost own the shaft).
The Council appointed Jacobs Engineers to find a solution for filling or closing up the collapsed vertical air shaft 20 metres deep x 8 metres diameter at this old landfill site at Great Ayton.
Access was the main problem facing a filling solution. The shaft was 3 km from the nearest road and at the top of a large hill over soft compressible soil topped landfill material mostly surrounded by fully cultivated fields with no access road capable of taking tipper trucks. On one side access was closer but there was a vertical grade of 1 in 1 from the foot of the hill running up to the top of the shaft. Vehicle access was out of the question.
DWG Resins were approached to fill the shaft using medium density Bacel hardfoam. Bacel foaming and pumping equipment is able to be demounted from the truck and still be used at remote locations without need for external power or water. The pumping equipment and materials were transported to the remote location by rough terrain multifunction forklift / telehandler. All materials were mixed off site and transported by “moffett mounty” truck to the access point in IBC’s and these were then transported up to the top of the shaft by the tracked telehandler and a small track mounted transporter.
BACEL pumping equipment only requires compressed air as the only means of power and so the compressor was taken up the hill also and located a short hose length from the shaft. The BACEL pumping equipment was designed for working in petrochemical situations and so the foaming is a “cold” electricity free process which reduces health & safety issues in wet, dangerous, or gaseous discharge situations.
The BACEL foam is produced in-situ from 2 base liquids stored and transported to site in 1000 liter IBCs from which large volumes of foam can be created (approx. 16 m³ from each IBC dependant on density required). This makes BACEL an ideal solution where access and logistics are a problem compared to foam cement “ready mix” trucks which carry only 6-8 m³ per delivery.
The work was carried out in 3 phases using expert mountaineering personnel provided by Dave Griffith’s Zenith Leisure to assist DWG Resins foamers with access. The shaft edges were continuously collapsing and no one was allowed next to the opening unless fully roped and tethered with safety harness.