Investigating sustainable solutions for roadside gully pot management

Scott, Karen M.

December 2012

Thesis or dissertation

© 2012 Karen M Scott. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Roadside gully pots are an important component of urban drainage, with over 17 million examples in service throughout England and Wales. Their main purpose is to retain sediments from road runoff, leaves and organic litter in order to avoid blockage or hydraulic restriction of the drainage system. Gully pots require regular mechanical cleaning to prevent blockages; indeed, blocked gullies were partially blamed for exacerbating flooding in the city of Kingston upon Hull in 2007. The rate at which mechanical cleaning and emptying of individual gully pots is required depends in part on the decomposition rate of the waste contained within. However, the physical and chemical processes which dominate decomposition processes are poorly understood. Understanding these internal processes, and whether climate and catchment area have the potential to affect them, is an important factor in developing sustainable solutions for managing gully pots, thus reducing the likelihood of future blockages.

In order to establish a basic understanding of internal gully pot processes, waste was collected from a range of catchment areas and across different seasons. This allowed temporal and spatial variability to be assessed. Model gully pots were then set up under laboratory condition to monitor the effects of moisture and temperature in situ over a six month period. Additionally, the effect of substrate addition, including glucose, Tween 80 and itaconic acid, was assessed within these model gully pots. A composting trial was also executed under mesophilic and thermophilic conditions assessing the effect of a substrate addition (starch) on the waste. In order to assess the processes within the waste, the organic matter content, moisture content and pH were all measured throughout the study. The effects of these variables on the microbial community were assessed using Biolog EcoPlatesTM, along with the assessment of enzyme activity using a fluorogenic approach.

Seasonality has little influence upon the waste, whereas geographical location exhibits a stronger influence. This can be attributed to the variable levels of foliage in the areas. Under laboratory conditions the waste was significantly affected by temperature, showing greater degradation at higher temperatures. Varying moisture levels, however, had little to no effect. Furthermore, slight increases in degradation were observed upon the addition of a substrate to the waste; this increase varied not only with the choice of substrate, but was also temperature dependant. The starch addition to the compost trial confirmed the waste’s ability to compost under both thermophilic and mesophilic conditions.

The results demonstrated the gully pot waste was able to decompose at a slow rate under replica field conditions. Using a substrate additive only increased this rate minimally, indicating that it would not be worthwhile for local authorities to use this as a substitute for, or in addition to, manual cleaning. However, the positive confirmation from the composting trial could be valuable when considering sustainable gully pot management in the future.

Department of Geography, The University of Hull
Coulthard, Tom J.; Adams, John D.
Sponsor (Organisation)
Engineering and Physical Sciences Research Council; Hull (England). City Council; Univar Corporation
Qualification level
Qualification name
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