Rising mains and pumping stations are critical assets in any waste water network and are designed to operate with a self-cleansing regime; however, this is sometimes compromised by a build-up of biofilm, debris and grease. Can ice pigging, a new technique currently applied to cleansing drinking water mains, offer a low cost solution for rising mains?
Obstructions in rising mains constrict the flow leading to increased energy use and frequency of pump operation, therefore traditional cleansing methods are often employed. In addition, cleansing to remove biofilms often forms part of an odour management strategy but this involves use of chemicals to mask the odour.
Ice pigging could offer an alternative; a pre-prepared slug of ice particles and water is injected into the main via a tapping point and is pumped down the rising main, removing debris and obstructions it encounters. The debris and residual melting ice can be passed forward without the need to remove the pig, as would be required with traditional techniques. However, it is not clear where or whether this new method is cost-effective when compared to standard swabbing and pigging.
This project will investigate ice pigging for rising mains and determine its costs and limitations through monitored field trials. Savings at the pump stations will be determined by recording the energy usage of the pumps pre and post cleansing.
BUSINESS BENEFITS TO CLIENTS
- Reduced pump and rising main failures, and consequential flooding of customers and pollution incidents, and reduced network odour complaints
- Rising mains and pumping station operational cost savings
Working with Mouchel Group we will undertake:
- Site identification and development of test protocol.
- Pre-cleansing energy and chemical use monitoring; rising main cleansing ; post-cleansing monitoring.
- Cost benefit /effectiveness analysis and reporting.
PROJECT OUTPUT AND IMPLEMENTATION
- Detailed “case-study” based report with cost benefit analysis and recommendations for operators to determine where and when to use ice pigging.
RELATED WRc WORK
- CP425 Pumping Stations management, 2010-2012
- CP371 Rising Main Inspection, ongoing
- CP017A Reducing Odours in Sewerage Rising Mains, 2004
- CP408 Septicity in Rising Mains and H2S Corrosion in Sewers, 2010