Technical Feature
Yorkshire Water and Hull County Council, while also providing a robust and efficient system ideally suited to the development’s challenging conditions.
These large diameter pipes not only conformed to Sewers for Adoption guidelines, they also managed the traffic loading from the road infrastructure. The conveyance and attenuation needs of the large site were met to the satisfaction of Yorkshire Water as well as other parties, and the engineered system design gained full Section 104 Approval for the adoption of surface water run-off into their watercourse, and Section 38 Approval for the installation of the system on the development site.
Plastic ideal for loading at Hull’s renewable energy site
Over 2 kms of large diameter PE pipe (from 400mm to 750mm) along with 50 custom-built manhole chambers, benching, ladders, stubs and lifting eyes, were specified at the world-leading Green Port Hull site, which is home to a wind turbine manufacturing facility and other world class renewable industries.
were constructed off-site and delivered ready for installation. It proved an easier and safer solution for the installation team, as piling was no longer required.
A total of 70 bespoke manholes ranging from 1200mm to 1300mm in diameter were provided across the stormwater, foul and culvert network – a truly large-scale development – along with 840 metres of plastic pipes fabricated off-site and delivered in sizes ranging from 400mm up to 900mm diameter.
Satisfying traffic loading requirements
In Hull, a new development providing 142 homes as part of the city’s ongoing regeneration saw large diameter plastic piping and modular manholes (constructed off-site) used to provide a number of benefits over a traditional concrete system.
The design included 12 pre-fabricated manholes featuring ready-to-install access points that could be integrated at any part of the network system. The manholes were benched and channelled in accordance with Sewers for Adoption guidelines.
Pipes and manholes were used to form four tanks to attenuate and convey surface water run-off from the development. Each tank was linked to a flow control chamber, featuring a flow control unit and penstock, to manage the release of surface water run-off into the approved watercourse. A pre-installed weir wall in each of the chambers provided a stable end connection to Yorkshire Water’s existing drainage system.
This was a value engineered solution, with pipes manufactured to the perfect stiffness classification to meet the site’s needs, together with convenient pre- fabricated pipework and manholes. The solution met the requirements of
A key issue for the site, along with the requirement for excellent drainage to withstand storm events and high levels of water running off factory buildings during rainfall, was a solution to withstand the abnormally high loading conditions caused by the giant wind turbines that were being installed adjacent to the pipelines. PE pipes were chosen due to the unusual and unsound environment requiring a product flexible enough to allow for land movement, but strong enough to not buckle or crack. The manholes were pre- assembled off-site, saving valuable time on the ground.
Beating the 1 in 100-year storm event
Other stormwater solutions using plastic manholes and pipes have been installed at sites including Houghton Regis in Bedfordshire, where the solution was designed to cater for ‘1 in 30-year’ as well as ‘1 in 100-year plus 30 per cent climate change’ storm events.
The bespoke stormwater solution incorporated staggered legs to take site conditions into account, and it also met site requirements and adopted elements laid out under Section 104 for approving water company, Anglian Water.
The attenuation tank supplied for the project featured a 3m diameter offset vortex flow control chamber to control discharge water from the tank at an agreed rate of 10l/s, so the local watercourse was not overwhelmed. To control additional flow
follow us on twitter @draintrader | April 2018 | drain TRADER 45
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