The Environment Agency’s MCerts legislation on self-monitoring of effluent flow has been in place throughout the UK since January 2004. All water utility consent holders must now have relevant sites inspected by an MCerts inspector, whose job it is to check that flow structures and instrumentation are accurately recording treated effluent data. Since the rules demand that inspections take place every five years, most sites are now about midway between inspections.
Under the MCerts regulations, the Environment Agency (EA) requires water utility consent holders to install and maintain equipment to measure and record instantaneous and daily cumulative treated flows at discharges above 250 population equivalent, or have dry weather flows (DWF) equal to or greater than 50m3/day.
The reported total daily volume of treated effluent should be measured with an uncertainty of better than ±8% and a confidence level of 95%.
The scheme also requires assessment of a quality management system (QMS) which should be in place to ensure that performance requirements continue to be met at all times. The QMS should include a quality policy, with a manual and procedures, an inventory of equipment and maintenance schedules, a standard approach to data treatment and guidelines for commissioning and changes.
Successful flow monitoring depends on the flow structures and their associated instrumentation being properly calibrated and well maintained, and the regular management and analysis of the data they collect. Used wisely, MCerts is a vehicle through which management has access to highly valuable flow data that allows them to monitor trends closely and so predict future needs and capital investment.
From visits carried out throughout the UK over the past two years, it has become clear that some operators are not maintaining their flow structures to MCerts standards, post certification.
It is as though, having worked hard to achieve initial certification (sometimes not without considerable effort and cost), these operators have breathed a sigh of relief and shut the paperwork away in a drawer to be forgotten about for five years. This short-term approach is an expensive way to achieve compliance because of the remedial work that is likely to be required. More than that, it misses the significant opportunity that reliable and robust flow data offers to the business.
Water companies are a bit like political parties – they operate on a five-year time frame. Partner agreements and management structures are all typically built around this timeframe where suppliers, framework agreements and internal personnel tend to change every few years. The result is often a lack of ownership for the bigger issues.
If operators really want to take advantage of the opportunities offered by MCerts – and the data it provides – then key personnel need to take long-term responsibility for flow systems. Key areas are: maintaining structures, recording and analysing data, conforming to QMS procedures and importantly, advising on flow related recommendations and future planning decisions.
But, since there seems to be a lack of understanding in the industry of these issues, then it is also up to the EA and MCerts inspection teams to better advise and communicate the benefits of good practice, and offer more comprehensive training.
The value of flow data is in the reliability and accuracy with which it is collected. A comprehensive maintenance programme that ensures flow structures and their associated instrumentation remain properly calibrated will protect the, often considerable, investment made in achieving MCerts compliance.
On the simplest level, it is cheaper and easier to maintain MCerts compliance than to start again from scratch every five years prior to inspection. More interesting though is the mine of useful information that reliable flow data provides. This is the key benefit of MCerts compliance that a few far-sighted water companies are now putting to good use.
One water company taking advantage of robust MCerts data is Southern Water Services (SWS). David Bone of the SWS Corporate Strategy Team says: “Reliable and accurate MCerts flow data enables us to improve our business strategies
in a number of ways.” He lists the business benefits as:
- Better Process control – flow measurement assists in flow balancing and ensuring that treatment processes are appropriately loaded
- Consent compliance – flow measurement can be used for proving compliance with consented dry weather flow and storm separation flow rate.
- Reliable data – for use in future works improvement planning – accurate flow data can be used in the design of individual process requirements as well as more extensive works improvements, ensuring that new constructions are optimally sized
- Monitoring catchment growth – changes in flow rates with time not only shows the impact of seasonal changes and variation in precipitation, but also reflects changes in the catchment itself
- Infiltration – Assessment of sewer infiltration using night time flows – flow measurement can be used to assess accurately the degree of infiltration and whether remedial action needs to be taken
There is a strong business case for a long term, balanced approach to planning and compliance based on reliable flow data. Companies that see the benefit of meeting this challenge will have clear efficiency and commercial advantages in years to come.