FP McCann Precast Concrete Attenuation Tank Installed at New Guildford Council Depot

Project: Stormwater Attenuation Tank – Guildford Borough Council Depot

Client: Guildford Borough Council

Civils and Structural Engineer: Burrows Graham

Main Contractor: McClaren Construction

Tank Installation Contractor: FP McCann

Product Supplied: Precast Concrete StormTank

FP McCann has designed and installed a 1,500m3 precast concrete StormTank on behalf of Guildford Borough Council and main contractor McLaren Construction at their newly located depot part of the “Weyside Urban Village”, within the Slyfield Area Regeneration Programme which will be a mixed-use development of approximately 1500 homes along with community and business uses.

On completion later this year the £38.4 million operational and administrative hub for the council will focus on sustainability and operational efficiency. Included in the design is a combination of blue and brown roof systems to manage water flow, air source heat pumps and solar photovoltaic panels.

As part of the building’s “Fabric First” approach encompassing SuDs, the FP McCann StormTank and integral pump system has been installed to manage excess surface water to reduce the flooding risk to the site’s low-level entrance.

Measuring 30.4 metres long by 24.2 metres wide, the tank has an internal height of 2.0 metres and with a water class tightness value 1 has been constructed using a total of 223 steel reinforced precast concrete panels consisting of 30 external wall units, 49 internal walls and 144 roof slab panels. In total, some 750 tonnes of StormTank sections were delivered in line with the FP McCann fixing team’s delivery and install sequence.

The precast concrete wall sections were positioned on the tank floor base foundation consisting of 216m3 of C40 insitu concrete and 49m3 of insitu blinding . A further 94m3 of concrete was pumped as final cover to the roof slabs on completion of the tank build. The StormTank panel sections manufactured at McCann’s state-of-the art precast facility in Byley, Cheshire were delivered to site over a period of 14 weeks for installation by the approved FP McCann specialist fixing team.

In conjunction with McLaren Construction and civils and structural engineering consultant Burrows Graham FP McCann value engineered the precast concrete tank system into the designated footprint by demonstrating increased performance and cost efficiencies over other considered tank extension options.

Commenting on the StormTank design and build, Stephen Petersen, Design Manager for McLaren Construction says, “We had to take into consideration a number of factors on the tank design, notably site ground conditions. Robustness and long-life, low maintenance performance were key to our choice of attenuation tank. Having looked at and considered carefully a few options, FP McCann’s StormTank fitted both the design and performance criteria. The McCann approved install team undertook the work in a timely, efficient and safe manner. We will certainly consider StormTank on any future similar projects.”

FP McCann’s 100 year design life StormTanks can be installed up to 6 metres high with no footprint size limitation and are designed for pedestrian loading through to LM1 highway loading. Internal design features can be added such as weir and baffle walls and penstocks or flap-valves can be pre-installed. Typical uses include:

• Clean Water Storage Tank

• Attenuation Tank

• StormBrake Chambers

• Pumping Stations

• Large CSO Chambers

• ASP Structures

• Basements