With a requirement to appropriately manage surface water runoff from its new extension, Madani Girls’ School turned to ACO Building Drainage and Aquality to construct a new blue green roof which doubles as a rooftop playground.
Set within a purpose-built Grade II listed Victorian building, Madani Girls’ School is based in the borough of Tower Hamlets and the suburbs of inner-city London.
With a mission to deliver a high-quality teaching and learning experience for its pupils, the school embarked on a project to extend and add a new library, IT suite and sports hall to its facility.
Given the nature of the site the only practical place to cite these new facilities was in the existing playground, and in order not to lose valuable outdoor play space, the decision was made to convert the roof space of the new building into a playground for the pupils. A key challenge facing the project was satisfying Tower Hamlets Council’s planning conditions in relation to surface water management. Namely, this was ensuring that the surface water will discharge at an appropriate rate to prevent downstream flooding.
Poor ground conditions on the site precluded the use of infiltration and other forms of surface SuDS systems to manage the surface water, leaving attenuation as the only viable technique. However, given the confined nature of the site that would have involved excavating a large proportion the existing playground and removing spoil by lorry to install an attenuation tank large enough to store the volume of water required to prevent flooding.
Even though the school is situated just off the A13 in Whitechapel with good access to the arterial road network, this method was deemed inappropriate. This was due to it being too costly and disruptive to the local community to transport the spoil from the site as this may have involved road closures and remedial costs to make good the local road.
Owing to the prohibitive site, the project team had already identified that a blue roof would be an ideal way of managing the surface water whilst also allowing multi-functional use of the roof space for the new building. However only preliminary calculations and an outline feasibility of the blue roof had been presented at planning.
To this end, Plumbsa Plumbing Ltd the subcontractors designated to work on the roofing and plumbing of the project, turned to surface water management specialists ACO Building Drainage and Aquality, stormwater management professionals, to help solve the issue.
Aquality undertook the hydraulic design and calculations and partnered with ACO Building Drainage to provide the ACO RoofBloxx geocellular tank, roof outlets, and blue roof flow control to provide a complete blue roof attenuation system that discharges at a maximum of 0.3 l/s. Comprising of a 255m2, 85mm deep storage tank constructed from ACO RoofBloxx cells, the system is intended to accommodate the one in 100 year rainfall event, whilst also accounting for 40% climate change.
To demonstrate the versatility and strength of the ACO RoofBloxx system, a porous asphalt playground was built over the top of the tank. Rainwater is designed to filter through the porous surface into the storage void. Alongside this, to ensure pupils had an aesthetically pleasing and biodiverse area to enjoy, an extensive green roof was incorporated around the perimeter of the roof.
Neill Robinson-Welsh, Consultant at ACO, said: “The extension at Madani Girls’ School has been a challenging yet highly rewarding project to be involved in. The loss of valuable outdoor place areas in city schools is an ongoing issue, so it was pleasing that the lateral thinking of the project team ensured that the new facility delivered as many benefits to the pupils as possible whilst also meeting the planning conditions. The project has really shown how versatile and cost-effective blue roof attenuation systems can be.”
Ali Adan from Plumbsa Plumbing Ltd said: “After discussions with Neill and the teams at ACO and Aquality, we were very pleased with the end result of the ACO RoofBloxx blue roof. It goes to show that even in some of the most difficult projects, rainwater can be managed with sustainability and amenity in mind, and SuDS principles can be followed. Not only did ACO and Aquality help with the consultation and hydraulic specification, but installation was also quick, simple and cost-effective.”
The Madani Girls’ School’s blue roof now works to prevent flooding whilst also retaining valuable outdoor space for students to enjoy and use for learning.
