Removal of trench support system
Removal of trench support system
Removal of trench support system
Installation of dewatering tubes
Installation of dewatering tube
Dewatering and preparing for excavation
Arrival of tanks from Carlow Concrete
Placement of tanks by Hiab crane
Tanks in situ
Concrete backfill placement
Inlet manhole, balance tank and reactor tank
Installing utility services

Shaftesbury Estates, Dorset

Installation of sewage treatment plant and associated works

Contracting direct with Shaftesbury Estates, MJ Abbott Limited was employed to design and install a new sewage treatment plant for St Giles House, the historic home of the Earls of Shaftesbury. The house, which has been unoccupied for fifty years, had fallen into a general state of dilapidation and is now the subject of a major restoration project.

The existing old style septic tank was no longer in working condition and was beyond economic repair. A new modern and fully automatic sewage treatment plant was designed in conjunction with Advanced Aeration (Bio Bubble Technologies) which uses intelligent SBR technology to treat the sewage effluent to an exceptionally high standard.

New gravity pipework had to be installed to replace old misaligned clay drains and also to pick up effluent discharged from nearby estate dwellings. Telecommunications and electrical ducting were also installed in common trenches to avoid further excavation in future years for utilities installation.

The project scope of works comprised:

  • Excavation through fine turf areas, turf carefully removed and rolled to one side
  • Machines and excavated materials operating on boards to avoid damage to sensitive areas
  • 160mm Ø sewer pipe laid on a minimum fall with granular backfill
  • Manhole chambers installed where required
  • Installation and subsequent removal of dewatering system and trench support equipment to allow safe excavation
  • Installation of 2 no Carlow Concrete 4.0m deep x 2.1m Ø concrete pump chambers
  • Installation of GRP control kiosk to house controls and GSM text alert units
  • Backfill and reinstatement of all working areas.

Due to the hugely challenging ground conditions, where the ground water table was struck at 1.0m and in combination with the inherently unstable ground, this project would not have been feasible without the expertise of Jim Usherwood of Dewatering Services Ltd.

Philip Rymer, Resident Agent for Shaftesbury Estates, commented: “We were all very impressed with the professionalism of MJ Abbott Limited. Although the conditions were very difficult their staff did everything possible to minimise any damage to the historic landscape.”

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