Venn Quarry Restoration
Client: Aggregate Industries
Value: circa £5,400,000
Form of Contract: ICC Infrastructure
Duration: 61 weeks
Dates: July 2017 – August 2018
- Restoration works to include excavation and remediation of soils
- Drainage installation and water treatment facilities
- Zero disposal off-site
- 500,843m3 excavation and fill
- 135,813m3 processing of material
- 118,583m3 importation of additional locally sourced fill
Project scope MJ Church worked as Principle Contractor to Aggregate Industries to carry out bulk excavation, remediation of soils and restoration work at Venn Quarry in North Devon. Aggregate Industries operated the quarry as a grit stone extraction site from the 1930’s, with stone contributing to several local major construction schemes including the A361 North Devon Link Road.
Following its closure in 2006, the site was sold to the Habitat First Group and planning permission approved to develop the site into an eco-friendly nature-based holiday community called Birchwood Lakes. The 63-hectare development will see the construction of 158 holiday lodges, a nature reserve and a 40-room hotel by 2020.
The contract would fulfil a ROMP restoration for Venn Quarry. The works comprised of partial backfilling of both existing Bailey’s and Spear’s Pits, using approximately 496,000m cu of fill sourced from within the quarry site. The fill comprised of approximately 202,000m cu of rock and 293,000m cu of quarry spoil obtained through excavation, drilling, blasting and crushing operations to produce a suitable fill. The backfilled materials were then capped (76,000m cu) and overlain with 130,000m cu of soil forming material sourced from off site and formed in two distinct layers:
• 0.5m layer of imported clay rich soil (Class 2) with no potential for future acid generation (pH neutral) and low course material content
• 0.5m of soil forming material to suit the requirements of the Landscape Management and Aftercare Scheme and to comprise of 200mm of topsoil and 300mm of underlying subsoil
Extensive drainage works were also carried out. Water within the site had a high PH value and was too acidic for immediate outfall to the natural river which is also a Site of Special Scientific Interest, therefor it was required to be captured, treated and then discharged. Our works involved the relocation of water treatment facilities, construction of three treatment ponds and an attenuation basin with an outfall built to discharge water back into the river following treatment.
Additional works included the construction of buttresses within the larger pit to strengthen and reinforce the quarry walls, installation of temporary haul roads to the quarry summit and removal of a 250m cu area of invasive plant species.