Introduction
HBT undertook the design & build of the foul & storm pump stations & manholes to adoptable standards in accordance with Yorkshire Water requirements
The scope involved:
- Foul Pumping Station – 3m dia & 13m deep
- Foul Inlet – 2.4m dia & 11m deep
- Storm Pump Station – 3m dia & 9m deep
- Storm Inlet – 2.4m dia & 6m deep
- 7 x 2.4m – dia manholes up to 11m deep
- 7 x lengths of storm & foul by Augerbore
Caisson Shafts & Augerbore
Objective
Persimmon Homes commenced works in Bessacarr and required the installation of foul & storm pumping stations. This included the deep runs of foul & storm pipe and manholes. The issue that Persimmon faced was that the depth of foul and storm onsite, coupled with the very high water table. The site also had high pressure gas mains running across the works.
Persimmon appointed HB Tunnelling to assist with the works, upon looking at the depth of the foul & storm lines, HBT recommended that these could be installed using the caisson shaft sinking technique and the all connection could then be installed using the guided augerbore technique.
The Challenge
The site presented a very high water table, requiring control by a dewatering specialist through the installation of deep wells to facilitate the safe construction of shafts and connections. As all foul and storm infrastructure on the site was to be adopted by Yorkshire Water, HBT began the design of the pump stations and deep manholes, which were to be constructed using the caisson method. Following design completion and approval—including flotation requirements in line with Yorkshire Water specifications—work commenced with the dewatering system
installation.
Once in place, the dewatering system was activated to pump and reduce the excess groundwater, enabling safe construction of the pump stations followed by all manholes using the caisson shaft sinking technique. All associated connections were installed using the guided augerbore method, with lengths of up to 45 metres. The remaining foul and storm connections required crossing a high-pressure gas main. HBT carried out settlement calculations, successfully demonstrating that installation would result in less than 2mm of settlement beneath the gas main.
“This was our first time using trenchless technique &
HB Tunnelling, we have heard great things about HBT but I can confirm that
they are very professional & organised company & we will be looking at the
next scheme to use this type of works”
- Persimmon
For more information please contact us on 0845 388 3325 or 07879 624900
