29 December 2014

GPRG expertise supports innovative product development

Staff from the GPRG and other research groups in the Dept of Civil and Structural Engineering have successfully undertaken experimental testing of the Gully Guard, an innovative flood mitigation technology manufactured by the Forest Group.

Crops in a field below a brewing thunder storm.

The Gully Guard is installed in roadside gully pots to reduce accumulation of sediment and minimise the impact of storm water run-off during flood events.

This novel re-useable product is designed to capture sediment transported in roadside drainage from construction sites, preventing it from being transported to streams, rivers and other sensitive receptors. At the same time, this function allows the sediment to be removed, preventing it from blocking the gully pot and ensuring flood water is removed from the roadside by the drainage system.

The Sheffield team were commissioned by Forest Group to determine the effect of the Gully guard on (i) water flow through gully pots, after installation of the product, and (ii) the potential retention of pollutants found in storm water via the sediment trapping capability of the product.

To answer the first question the team used a full-scale test rig, the only one in the UK, to reproduce flow and sediment transport under different simulated storm events. They compared the performance of the Gully Guard when installed and not installed in a gully pot.

The study showed that the Gully Guard does not significantly affect the function of a gully pot in taking drainage water away from the roadside and provides an important function in capturing sediment transported in such drainage. 

To answer the second question, the team undertook laboratory sorption tests using the sediment retained by the Gully Guard in the first part of the study.

They examined the sorption by these sediment fractions of key groups of chemicals often found in urban and agricultural road-side run-off. The chemicals were polyaromatic hydrocarbons (PAHs), heavy metals and nutrients.

The experiments showed that the Gully Guard is very effective in trapping the majority of the sediment and a wide range of organic and inorganic chemicals that may adsorb to this fraction from the storm water. 

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