Showcase of innovation | Stormtech does SuDS differently


Stormtech SuDS Mitigation System Targets UK Market

SAdvanced Drainage Systems’ tormTech arch-shaped SuDS attenuation chambers have been used on over 50,000 projects worldwide. New Eurocode modeling demonstrates that they are also suitable for projects in the UK and Europe.

The StormTech SuDS underground attenuation system, which exploits the structural properties of the arch, is currently being installed on construction projects in the UK. Recent installations include one at Barrhead Retail Park in Scotland and one at Panattoni’s Logistics Park in Derbyshire.

The heart of the system is its corrugated thermoplastic chambers which have an elliptical arc-shaped cross-section.

This shapes the embedding around stone arched rooms and structural columns, transferring loads away from the chamber in the stiffer material surrounding the chambers so that they can be installed with a shallow and deep cover.

Designed for layout flexibility, ease of installation and transportation, the StormTech system can also incorporate an integral means of removing surface runoff pollutants at no additional cost. This is easy to maintain and can eliminate the need for expensive pre-treatment systems.

StormTech chambers are designed to codes and standards published by the American Association of State Highway & Transportation Officials and the standards organization ASTM International. To facilitate their acceptance in the UK and other European countries, ADS commissioned a study to model their performance under the
Design methodology of Eurocodes.

ADS UK manager Stuart Crisp explains: “The American design philosophy is different from Eurocode. This study reflects the American approach and shows with complete certainty that the StormTech system performs to Eurocode design patterns, when installed using our standard details.

Test scenarios

The seven different sizes of the StormTech chamber were evaluated using a Finite Element Analysis (FEA) model, which looked at the limit state failure modes, as outlined in EN 1991- 2 – Eurocode 1 – Actions on structures – Part 2.

Some may be familiar with Ciria C737, which covers the design of thermoplastic boxes for groundwater mitigation, which also suggests Eurocode modeling as a means of demonstrating structural suitability.

In accordance with the ISO/DIS 4982 standard which covers arched chambers, the FEA model was used to test the various chambers under the most demanding loading scenarios. At shallow depths, live surface traffic loads are most likely to cause failure. For maximum coverage, the long-term load of the backfill material must be taken into account.

Load models for four different stress and fatigue cases were applied, according to
EN 1991-2 with cover conforming to the ADS StormTech construction guide.

  • Load case 1: minimum coverage and load model 1 (paragraph 7.2)
  • Load case 2: maximum coverage and load model 1 (paragraph 7.3)
  • Load case 3: minimum coverage and fatigue load model 3 (paragraph 7.4)
  • Load case 4: minimum coverage and load model 1 with braking forces (paragraph 7.5)

The modeling takes into account the shape of the arcs and the properties of the materials. The sections are injection molded from a thermoplastic, which means that the long term performance of the material under load must be considered.

Proven performance

FEA modeling has proven that all StormTech chambers are structurally adequate for each of the load cases detailed above. For minimum coverage situations, there is significant additional structural capacity. For maximum coverage, more of the chambers capacity was used, but they were still comfortably within their capacity.

Crisp hopes these calculations will help engineers and contractors justify using StormTech.

  • Published in association with StormTech

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