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Showing posts from 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.

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 p…

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 …

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 ac…

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…