Design skills steel sites to stormwater problems

Our weather is showing signs of excess. In the UK alone, torrential rain and frequent examples of flooding repeatedly follow periods of heat and drought.

Government guidelines now combine with existing planning restrictions to place the maximum pressure yet on UK developers and contractors of new construction sites – and to make arriving at the most cost effective solution in stormwater attenuation a truly key issue.

Of the three main options – corrugated steel holding pipes and tanks, polypropylene versions of the same, and pipe-fed cell systems – the corrugated steel option has proved the most attractive, particularly when the UK’s leading manufacturer, us, back our offer with a full design solution for the project in question.

So rapid has been the rise in importance of stormwater attenuation systems that a sizeable minority of project engineers have had no experience of incorporating them. Tubosider provides a free-to-client service which calculates the most cost effective solution based on all nine potential parameters (see below).

This assumes engineers can establish the first – the volume of storage required. But in the 10% or so cases where they have not, we can also assist in establishing the volume of storage using the storage module of its microdrainage software, providing all the other required parameters are available.

Whatever the volume, developers will want to make maximum use of the land available. Our systems not only qualify for installation under landscape areas to full carriageway loadings, but their discharge methods – pumps or flow regulators – can be incorporated in the tanks themselves, saving space and cost.

The stormwater storage requirement depends on the rate of discharge allowed by local environmental agencies, who must ensure that sewage and water treatment works are not jeopardised. Car parks and roof areas are two critical factors in stormwater build-up, but car parks themselves are ideal for locating a stormwater attenuation system beneath.

Arriving at the most cost effective solution means taking account of nine parameters: 

  • volume of storage required – say 550 cubic meters
  • gravity or pumped system? – say gravity
  • if gravity, the depths available – say 4 meters
  • if pumped, the maximum desired depth – not applicable here
  • site constraints (the plan area available) – say 42 x 15 meters
  • loading criteria – HA (Highways Agency) only
  • design life required – say 100 years
  • allowable discharge – say 11 liters/second
  • environmental classification – say non-aggressive

With the widest range of pipe sizes (0.3m to 3.6m diameter) and stormwater attenuation tank sizes (from 0.6m diameter) in the industry, manufactured in thicknesses from 1.5mm to 3.5mm, We have the capacity to design solutions to match any project. Using the above details as an example, it first determines the steel thickness required to accommodate the height of cover, loading criteria, design life and environmental classification – in this case 1.5mm.

With a volume of storage of 550 cubic meters and an available area of 42 x 15 meters, the best available solution using a 1.8m diameter tank (giving an end area of 2.54 sq m) would be 550/2.545 = 216.110 linear meters, designed as a manifold of five parallel tanks.

Backed by on-site support, our tanks and pipe systems such as Twinstore are specifically designed to provide the most cost-effective and practical solution to any project, whatever the parameters.