Articles | Volume 10, issue 2
https://doi.org/10.5194/dwes-10-45-2017
https://doi.org/10.5194/dwes-10-45-2017
Research article
 | 
06 Jul 2017
Research article |  | 06 Jul 2017

Quantity and quality benefits of in-service invasive cleaning of trunk mains

Iftekhar Sunny, Stewart Husband, Nick Drake, Kevan Mckenzie, and Joby Boxall

Abstract. Trunk mains are high risk critical infrastructure where poor performance can impact on large numbers of customers. Both quantity (e.g. hydraulic capacity) and quality (e.g. discolouration) of trunk main performance are affected by asset deterioration in the form of particle accumulation at the pipe wall. Trunk main cleaning techniques are therefore desirable to remove such material. However, little is quantified regarding the efficacy of different maintenance interventions or longer-term changes following such cleaning. This paper presents an assessment of quantity and quality performance of a trunk main system pre, post and for 12 months following cleaning using pigging with ice slurry. Hydraulic calibration showed a 7 times roughness height reduction after ice slurry pigging, evidencing substantially improved hydraulic capacity and reduced headloss. Turbidity response due to carefully imposed shear stress increase remained significant after the cleaning intervention, showing that relatively loose material had not been fully removed from the pipe wall. Overall the results demonstrate that cleaning by pigging with ice slurry can be beneficial for quantity performance, but care and further assessment may be necessary to realise the full quality benefits.

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Short summary
This paper presents an assessment of quantity and quality performance of a trunk main cleaning using ice slurry pigging intervention. Hydraulic calibration showed a 7x roughness height reduction after ice slurry pigging, although turbidity response due to carefully imposed shear stress increase remained significant, indicating loose materials had not been fully removed from the pipe wall. Due to ongoing material accumulation, one-off intervention may not be sufficient to manage the quality risk.