Duncan Ross Ltd under Volker Stevin Ltd secured the contract to construct a new flood defence system to reduce the flood risk from 20% to 1% chance in any one year. Three new floodwater storage areas have been created to contain enough floodwater to fill 20 Olympic swimming pools. The West Lakes Academy sports field is the largest water storage area, the original Redgra playing surface was deemed unfit for use during any wet weather and consequently removed off-site.
The field required a comprehensive gravitational drainage system that was required to work in conjunction with the newly built flood control and defence systems surrounding the area. The Redgra area was to be replaced with natural grass sports pitches. The project included the following works:
- Removal of all vegetation from the existing grassed areas (7,330m2)
- Excavate material off Redgra area and cart material to tip (20,100m2)
- Importation and spreading of approved topsoil across the Redgra area (4,900 tonnes)
- Surface grading and trimming of imported topsoil (27,430m2)
- Stone clearance/removal/burying to 20mm diameter (27,430m2)
- Installation of inspection chambers and headwalls (7 Nr)
- Installation of collector, cut off drains and lateral drains at 7m centres (4,560m)
- Importation and amelioration of approved sand at a depth of 50mm (2,700 tonnes)
- Final trimming, finishing, fertilising and seeding works (27,430m2)
- Initial annual maintenance (inc. Mowing, herbicide treatment, fertilising and overseeding).
- Installation of gravel and sand slit drains at 1m centres (27,430m2)
- Sand topdressing and vertidrain aeration applications (660 tonnes)
- Ongoing establishment and maintenance
Once there was sufficient grass cover accompanied by good root depth, the initial phase of the maintenance programme began. In late September, Phase 2 of the drainage scheme was set to commence ensuring good ground and weather conditions.