Managing sewerage assets

Jim Grandison from IETG looks at how improvements in data acquisition can enhance performance in sewerage management

Last year’s Environment Agency (EA) Spotlight report brought into sharp focus some water industry performance and accountability issues. According to the EA, the water industry was responsible for more than one in six of the 1,468 serious pollution incidents reported in 2002. An estimated 7,000 properties in the UK are flooded by sewage every year, leading Ofwat to allocate £1B to tackle the problem in the final determinations for PR04.

According to John Reynolds of Portsmouth University, Britain’s sewerage system has endured years of neglect and is approaching the end of its useful life. A former water company engineer, Reynolds analysed the amount of renovation and maintenance work carried out on the network since water privatisation and, according to his research, at the current rate of investment it would take 1,500 years to renovate Britain’s underground pipes. His research was undertaken prior to the announcement of £3.5B for sewerage service quality programmes in AMP4.

While time and cost constraints make it impractical to replace all of Britain’s ageing sewerage system, new technology means monitoring systems can forewarn water service providers (WSPs) of potential problems, such as blockages and discharges. WSPs need to manage their assets carefully to maintain service delivery targets at least cost – an effective way to achieve this is through comprehensive data collection.

The last five years have not only seen an increase in the amount of regulation but also the scope of implementation and severity of penalties for failure. A barrage of regulatory drivers such as AMP/Q&S, combined sewer overflows (CSOs), Urban Wastewater Treatment Directive (UWWTD), Shellfish Directive, Consent to Discharge and the Water Framework Directive (WFD) now oversee the performance and operation of sewerage assets.

Additionally, there are the financial penalties for breach of consents and pollution. Typically the fines themselves are not punitive. The scale of punitive damages is increasing yearly as they show a decreasing tolerance to pollution. Fines incurred by the offending companies represent only a small proportion – the total sum includes the public relations implications, clean-up costs, management time and legal fees within a culture of increasing social responsibility. Solutions that provide not only continuous monitoring capabilities but also significant cost and operational benefits are therefore essential.

Minimising business risk and improving the certainty of decision-making requires a more detailed analysis of network systems than previously undertaken. As the efficient operation of assets depends on their condition and performance, it is critical to base inspection and intervention strategies on optimising the benefits to both the service and environment by using whole life asset data. While data is commonly used to improve asset performance through emergency repair or replacement, it is rarely used to monitor the degradation or performance curves in operation and modify asset use accordingly.

Detailed data can enhance performance using a risk-based approach that includes all possible outcomes and events, rather than just those that are more likely to happen. By collecting comprehensive data sets, all outcomes can be reviewed and performance maximised based on real applications. The impact of intangibles on risk strategies can also be tested, for example the long-term effects of climate change. Perhaps the biggest driver for comprehensive asset data is the reduction in programme timescales by driving intervention programmes directly from investment plans.

At the same time, the data can be used to demonstrate to Ofwat/WICS that normal business is continuing and improving service delivery. A continuous obstacle in the way of data collection has been the availability and use of cost-effective technology – while water companies may be demanding in their approach, the volume of sales is rarely sufficient to drive prices down to an economical level. WSPs currently purchase a wide variety of equipment including weirs, flumes, telemetry systems and sensors that have to be competitively tendered and funded as capital assets – but historically this system has been fraught with redundant technology, poor implementation and errors in installation.

Advances in data measurement have encouraged the production of low-cost, simple and effective measurements for level standards in the catchment. Equipment such as HawkEye is Atex certified but is battery-powered, thus avoiding the need for expensive road cuts, roadside cabinets or aerial/solar panel poles. It uses non-contact measurement sensors to provide reliable and repeatable data with the lowest cost of ownership. Data is communicated via mobile phone technology so alarms can be raised and trend data can be collected on a routine basis.

Knowledge is power

The benefits of long-term flow data are demonstrated by an improved understanding of the hydraulic performance of sewerage networks and more precise models for planning and investment decisions. Instrumentation, however, is more complex and since the sensors are in the flow, they need more operational care and attention. Data and alarm connectivity is achieved via telemetry and the data can be made available through standard options including corporate database links, web-enabled browsers and data bureau services.

There is also the opportunity to interface long-term/permanent data networks to the existing hydraulic model assets and drive additional value from these data sets, which could become a live tool to assist with catchment management and planning. Cost-effective data solutions, together with sophisticated data handling tools, can yield improvements against two key business drivers for CSO performance monitoring – improved levels of service and a reduction in the number of fines and pollution incidents. Currently, the main data requirement at CSOs is to demonstrate consent compliance, however there is a growing understanding of performance issues.

What is more important is the incidence and likelihood of dry weather spills or spilling more frequently that consented. Not only is this of environmental significance (due to the higher concentration of spills in dry weather), it also indicates a more serious problem since this is what CSOs are designed to prevent. Monitoring systems can also provide information on CSO operating levels that can be used to estimate hydraulic loadings on screens against their design limits. Silt or a downstream blockage can reduce a CSOs capacity, triggering an early onset of overflow activation or premature screen use.

Simple level measurement can provide a cost-effective tool to plan routine maintenance and silt removal programmes. Alarm triggers will notify of overflow activation and remove the need for routine cleaning visits. Flow to treatment is a vital indicator of cost and performance of collection systems behaviour, but not all WSPs are benefiting from the accuracy and reliability of the data. Not only does flow quantity determine treatment chemical costs and pumping costs, it can also affect consent compliance, risk of watercourse pollution and even fish kills.

Monitoring levels offers long-term strategic data for infiltration reduction programmes, seasonal trends and population growth for accurate and timely expansion or replacement planning. Treatment works data can also be used for billing, defining best treatment strategy and examining the relationship between dry weather flow and full flow to treatment. The balance of storage and capacity can be optimised, leading to lower capital costs and maximised storage.

There is clear evidence from other industrial sectors that investment in data collection can drive operational expenditure and influence whole life costing – existing off-the-shelf systems can provide a strong enhanced data and alarm management functionality. These systems, used extensively in the offshore oil and gas sector, are now being installed in a number of other sectors including retail, refrigeration and mobile telecommunications asset management. For this to translate to the water sector, investment must move forwards in harmony with ongoing research into the accuracy and reliability of data gathering assets and, just as importantly, data system intelligence. The good news is that these sort of systems already exist.

Developing a strategic approach to managing sewerage assets should deliver the cost/benefit trade-off that is the holy grail of WSPs. The balance of CAPEX and OPEX can be optimised at the lowest possible costs without diminishing asset performance or service life. It is now clearly possible (and affordable) to provide a system that integrates all the data gathering opportunities and allows WSPs to optimise the performance of sewerage assets through improved wide scale data acquisition. Many of the systems discussed can be applied to other areas to produce significant benefits – areas currently under research include monitoring sewerage flow levels in flat/risky sewers, sewer flooding and short-term emergency deployment.

Those who latch on early to this technological acceleration will be able to make the most of the advantages and be in the driving seat of change. After deciding on what technology to invest in, and when, there will be the task of managing the increased data flows, both from a technological and organisational viewpoint. The final challenge will be to make sense of all the additional information available.

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie