2023, HWM Group undertook a monumental civil engineering project, constructing the extensive In STIHL Head Office and cutting-edge warehousing facility in Camberley. The project, commissioned by our client Glencar Construction, stands out not only for its scale but also for its commitment to environmental sustainability, securing BREEAM Certification, the foremost sustainability assessment method for building projects worldwide, during the planning phase in 2022.
The comprehensive scope of work assigned to HWM Group encompassed a range of tasks, from initial site clearance and the removal of Japanese Knotweed to the intricate details of landscaping. The site, located adjacent to the A331, required a meticulous remediation strategy, produced in house, to implement the processing and treatment of 50,000m3 of contaminated arising. HWM Group deployed their mobile treatment permit to the site to facilitate this. Part of our remediation strategy involved the construction of a Load Distribution Mat (LDM) to the office and warehouse, an area extending to 11,500m2.
The project encountered some challenges from the outset due to the need for a significant clean-up of a derelict site, involving the removal of logs, lumber,and green waste. HWM Group, however, demonstrated environmental responsibility by repurposing 100 per cent of the green waste materials for biofuel, composting, and mulch products. Additionally, we initiated biodiversity offset planting schemes in the local area to compensate for the greenerydisplaced during construction.
The initial Section 278 works included the construction of site access roads with HWM taking charge of internal site roads, service yard slabs, Dock leveller construction, sprinkler base, retaining walls and car park construction. Notably, the ground stabilisation efforts under the car park and yards were substantial, requiring the use of recycled aggregates before the main contractor applied tarmac.
HWM Group diligently adhered to the project timeline, commencing foundation work for the 11,500m2 facility as scheduled. This involved cropping piles to correct levels, cut and bent reinforcement, installing holding down bolts and concreting for the foundations, enabling Glencar's steel frame contractor to take over seamlessly. The subsequent focus shifted to significant drainage work across the site, a task complicated by the challenging ground conditions of the floodplain.
Navigating adverse weather conditions posed a particular challenge, especially during one of the wettest summers on record. HWM Group addressed water drainage and diversion issues, overseeing the installation of new drainage works, trenching for incoming water mains, and excavated and lined two large swales (volume 15,000m3) as part of a flood risk mitigation zone. The complexities of working in a floodplain were further evident in handling ground and surface water issues throughout the project.
The drainage infrastructure installed by HWM Group included two petrol interceptors, one storm pumping station, and one foul pumping station, with approximately 700 metres of rising main. The team also had to interface with existing Thames Water culverts and overflow systems, presenting additional challenges that were successfully managed.
In summary, HWM Group's involvement in the development of the STIHL Head Office and warehousing facility, working meticulously with our client Glencar Construction, stands as testament to our team’s civil engineering expertise and commitment to overcoming diverse engineering build challenges.
The schedule of work HWM Group were contracted to undertake included:
• Site clearance, tree removal, JKN removal (Japanese Knotweed)
• Screening and processing on site, historic stockpiles c.50,000 m3
• Crushing site won concrete c.6,000 m3
• Reduce dig
• LDM stabilisation and stoning
• Foundations
• Drainage
• Service Yard Slabs
• Retaining Walls
• Sprinkler Base
• Dock Leveller
• Services / Ducting
• Kerbing
• Landscaping
Contract value £7m.