26 Water / Wastewater
AN MCERTS INSPECTOR’S VIEW OF THE CURRENT MCERTS PROGRAMME (SELF-MONITORING OF FLOW)
Having worked as an MCERTS Site Inspector, since the early days of the scheme and having carried out, at my last estimation, around 5000 MCERTS Site inspections across virtually all the Water companies and industry, I am often asked for my views on the MCERTS programme. For those unfamiliar with the MCERTS programme, MCERTS is the Environment Agency’s Monitoring Certifi cation Scheme. The scheme applies to businesses that are environmental permit holders who produce potentially harmful emissions to air or discharges to water.
T
he aim of the scheme, with regards to discharges to water, is to provide an independent assessment of self-monitoring
of effl uent fl ow by qualifi ed MCERTS Inspectors from approved companies, such as Environmental Flow Ltd. There are four other approved MCERTS companies in the UK and together we carry out all of the UK’S MCERTS Site Inspections.
Our clients are the Process Operators who the Environment Agency require to have their fl ow-monitoring arrangements independently assessed and certifi ed as conforming to the requirements set by CSA Group Testing UK Ltd (under the MCERTS Certifi cation Body). These Operators are from all over industry and include water companies, the food industry, the waste industry, manufacturing and much more. Compliance is achieved following the satisfactory completion of both a site inspection and a management system audit. The CSA group then issue the MCERTS Inspection Certifi cate, which is valid for 5 years. MCERTS Inspectors carry out the site inspections and issue the MCERTS Site Inspection reports.
When on site the most frequent question asked is: “Has it passed?” The next most frequent question, is “Why do sites fail their MCERTS? Before exploring the reasons sites fail their MCERTS inspections, it is important to point out that more sites now pass their MCERTS inspections fi rst time compared with the early days of the scheme. This is despite standards becoming more rigorous in recent years. This points to the success of the scheme, which is now in its 20th year. Compared to the early years of the scheme, most Process Operators are much more aware of the MCERTS standards and requirements and have a greater respect for the scheme. This means that the scheme is working. More Sites are passing their MCERTS and therefore
IET JANUARY / FEBRUARY 2023
I feel some personal satisfaction in being part of something that is helping to improve water quality in our rivers and coastal waters. Afterall, if Process Operators do not know the quantities of effl uent they are treating - and releasing into the water course - how are they supposed to effectively treat the effl uent?
The main causes of sites failing
their MCERTS Failures are still relatively common, and they are usually a result of fl ow measurement systems that are poorly maintained, poorly installed or badly designed.
A poorly maintained fl ow-measurement system can result in a site failing its MCERTS inspection. A common point of failure, with mag meters, on closed channel systems, is a build-up of detritus on the inside of pipes. This will affect the accuracy of the readings from the fl owmeter and will generally cause the fl ow-meter to over-read, fail It’s MCERTS and ultimately increase the costs to the Process Operator. Build-up in pipes often causes the MCERTS Inspector a problem in verifying the fl owmeter as it will also affect clamp-on meter’s - often used in secondary verifi cation - ability to function.
Unfortunately, even the most well-maintained sites are doomed to failure if the fl ow-measurement system has been badly designed in the fi rst place. Examples of poorly designed fl ow measurement systems include systems where hydraulics downstream of open channel structures cause the fl ume to drown out. A drowned-out fl ume means that the fl owmeter is unable to read all the fl ows that are passing. Unfortunately, a relatively common design issue is where a fl ow measurement system has been designed to the minimum standards for their predicted fl ow rates, allowing no room for expansion, and then a short period later, the system fails because fl ow rates have increased and the system can no longer cope with the increased fl ows. A common example of this is where fl ow rates increase at Sewage Treatment Works, perhaps due to a new housing development, and then the current system cannot cope and has to be replaced at a huge cost. Furthermore, I often have to fail sites that were initially designed well, but alterations have taken place that interfere with accurate fl ow measurement. The biggest cause of this is where samplers and wash water pumps have been fi tted into weir chambers resulting in an adverse effect on the hydraulics of the fl ow measurement system.
Photo above illustrates detritus build-up inside a magmeter. Clearly, this magmeter was in need of a better cleaning regime.
Similarly, for open channel inspections, detritus in the channel or weir chamber is the biggest cause of failure. Again, the detritus causes fl ow meters to over-read and it can create turbulence in the channel which again affects the accuracy of fl owmeters. Other maintenance issues causing open channel systems to fail their MCERTS include fl umes starting to detach from the channel, weirs leaking and in fi nal effl uent weir chambers, algal growth and moss. More unusual maintenance issues which I have come across have included chambers which are heavily contaminated with rat faeces and rat poison and visible rats’ nest within pipe lagging. The presence of rats alone, would not cause a site to fail its MCERTS, but there have been rare occasions where a secondary verifi cation cannot be carried out due to contamination risks.
This photo shows a completely over-whelmed and drowned out V notch weir as a result of the factory expansion and subsequent increased fl ow rates, with no consideration for the fl ow measurement system. It also illustrates an over-cluttered chamber full of sample probes and pumps. As a result, it failed its MCERTS audit and had to be replaced.
Poor installation is another cause for site failures. Over the years I have seen fl umes and weirs installed back-to front, mag meters not installed on straight sections of pipe and not running full and poor electrical connections where the wrong cables have
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