Friday, 29 April 2016

Water Engineering Expert: Expert Witness Enquiries: An Applied Guide to Water and Effluent Treatment Plant Design

I have put a couple of new bids in recently for expert witness engagements, one of them local, and one in the German-speaking world. Expert witness engagements are always interesting, with their combination of technical, legal and financial matters which could not be resolved without calling in lawyers and independent experts, but the enquiries I have had recently have had some especially interesting aspects.

I also signed a contract this week to produce a third book provisionally titled "An Applied Guide to Water and Effluent Treatment Plant Design". I'll start writing it as soon as the second book (Plant Layout) is submitted. The first one is still selling well, and I am appearing at Chester University next week to share some of it with the students there, as well as my ideas about how chemical engineering education can be improved.

Friday, 22 April 2016

Expert Witness: Sewage Sludge Thickenng and Dewatering. "When you Say your Treatment Plant "Works", What do you Mean by "Works"?"

I was up on Scotland yesterday looking at a sewage sludge thickening and dewatering plant with a view to providing an expert advisory report to a contractor in dispute over whether the plant works. As is so often the case, many of the answers depend on what you mean by the word "works".

Anyone tasked with writing the specification of a performance trial needs to be very clear about the answer to the question "what do I mean by works?".

If we want something to be "25% X", do we mean "no less than 25%X", "25%(+/- 1%) X ", or "on average 25%X". If we mean average, which kind of average do we mean?

Do we want a statistically significant result? How significant does it have to be? What statistical test must we apply?

When we say 25%, we are implying that there are two significant figures. If there were three, it would be "25.0%". 24.5% is 25% to the implied two significant figures, so anything over 24.5 is arguably a pass.

Under what conditions is the trial to be conducted? Who is to operate it? What will be done in the reasonably common situation where the client cannot provide the plant with feedstock to the promised specification?

From a practical point of view, if the answers to these questions are not decided in advance, they are hostages to fortune. From a strictly scientific point of view, the lack of declarations on these issues prior to test commencement invalidates the test, for technical reasons to do with the theory of design of experiments.

I see a related situation commonly in other troubleshooting and expert witness situation where no performance trial was ever carried out. Plant may have never been capable of reliably meeting consent and therefore run in a non-compliant fashion for years.

I can have great difficulty in such situations to get clients to understand that discharge consents are absolute, and non-negotiable, and every failure is a breach of the law, as I have discussed previously. Sometimes it takes more than one prosecution by the EA to make them understand.

Friday, 15 April 2016

Expert Witness : Water Engineering: Scottish Law and the Status of the Expert Witness

I picked up a new expert witness instruction for a commercial dispute to do with sewage sludge handling in Scotland this week.

The Scottish courts seem less bothered about written reports with signed statements of truth than the English courts, (preferring oral evidence) but the main difference seems to be the uncertainty about the status of the expert.

I used to live in Scotland, so I knew that their law was different, but I was surprised to find that the status of the expert witness in Scottish courts is in continuing dispute. There has been a lot of commentary recently about the examination of the role of the expert witness in Scottish courts in the case of Kennedy vs Cordia.

In essence, the court had originally ruled on the basis of accepting expert evidence from a consulting engineer, a Mr. Lenford Greasly (many internet sources mis-spell his name Greasley).

On appeal, it was held that the expert's evidence in this case was not admissible, as it did not meet the specific criteria for evidence to be considered as ‘expert’ and was rather "nothing more than what a reasonably inquisitive and intelligent person might have discovered by, for example, looking material up on the internet.” In other words, the court considered there to be no such thing as an expert in Health and Safety at work.

The court wrote that “if the opinion of a witness is not based on the principles of some recognised branch of knowledge in which he has particular experience and expertise, it is useless ‘expert’ evidence and should be held inadmissible.” As the court’s initial decision was based on the expert's evidence, their conclusions were not considered to have been substantiated.

Recently this case went on appeal to the United Kingdom's Supreme Court, who reversed the decision of the Scottish appeal court, and found that the expert did in fact have relevant qualifications and experience, and was therefore properly treated as a "skilled witness" offering expert evidence.

The important factors in determining whether skilled (expert) witness evidence may be offered in Scottish courts are:  (1) whether the proposed skilled evidence will assist the court in its task; (2) whether the witness has the necessary knowledge and expertise; (3) whether the witness is impartial in their presentation and assessment of the evidence and (4) whether there is a reliable body of knowledge or experience to underpin their evidence.

Blogs and other public discussions amongst lawyers since this ruling mostly express the view that the status of expert witnesses in Scotland is now rather clearer than it was previously. Scottish courts still do not however have any equivalent of the English CPR Rules whose Part 35 sets out clearly the way an expert witness should serve the court.

Friday, 8 April 2016

Industrial Effluent Treatment Plant Problems: Why Employ a Process Engineer?

We put another troubleshooting report out this week on an underperforming industrial effluent treatment plant with a range of options for getting it to work properly.

We have looked at a number of plants recently where part of the problem is that some of the equipment is oversized, and some of it undersized. The essence of good process engineering is that the equipment is designed to work together across a range of flows and contaminant loadings.

I had a mismatched equipment situation like this last year caused by a decision by a large international civil engineering firm to do without a process designer. This unwise experiment had two severe effects of the effectiveness of the plant. As well as the mismatch in equipment sizes, a number of unproven technologies were selected, and the implications of their not working as advertised were not considered.

There was a secondary effect of the lack of a process engineer's input to the design: the layout was only just large enough  to accommodate the specified equipment, which created great difficulties in modifying the poor design.  

Why employ a process engineer? To get the right sized equipment, laid out properly to work reliably, cost effectively and safely. Doing without one in the past has proved a false economy for many of my clients.

Friday, 1 April 2016

Troubleshooting Submerged Aerated Filters : Deja Vu

I carried out a troubleshooting visit earlier this week at a food production facility. This is the second submerged aerated filter (SAF) effluent treatment plant I have looked at this year, and (like the first) it didn't seem a good match to its duty.

As I said last week, the first stage of troubleshooting is understanding any data available, and getting a feel for the margins of error attached to it. The data has to be supplemented with on-site testing, noting the appearance, odours, and residual evidence of past problems of the plant, and structured questioning of staff.

Once all of the data has been gathered and analysed, it is usually the case that there are a number of overlapping problems. It if frequently the case that the problems are worse than the client thought they were.

However, everything is possible in engineering. Problems can always be fixed, though this is not always as cheap or quick as clients might hope.

However, it is often the case that at the point where I troubleshoot a plant, several attempts have been made to apply cosmetic or superficial fixes. Though these may be individually cheap, they often add up over time into more than it would have cost to get to the bottom of the problem as soon as it manifested.