Floods...

[Jon Maine]

So do you still do that?

 

[biffvernon]

Yes Jon, some wise thoughts there.

I'm rather skeptical about the oft mentioned horrors of the unhealthiness of floodwaters. A little back of envelope calculation of water volumes suggests that the dilution rate of the 'dead rats etc' renders the waters of the Greater Derwent not far off drinkable, once the mud has settled out.

 

[FamilyWiggs]

That's all very well Biff, unless you're the poor sod who gets the glass with a rat in it!

 

[Penners]

:lol: :lol: :lol:

 

[Ushy M]

I'm rather skeptical about the oft mentioned horrors of the unhealthiness of floodwaters. A little back of envelope calculation of water volumes suggests that the dilution rate of the 'dead rats etc' renders the waters of the Greater Derwent not far off drinkable, once the mud has settled out.

The problem lies less with the number of dead rats than the volume of human excrement which finds its way into flood water as a result of the antiquated sewerage system. In heavy rain this overflows, flooding into the rivers. I'm afraid flood water can be extremenly foul and toxic.

 

[JoceAndChris]

It interests me that what is foul and toxic to one is quite acceptable to another. Take my unfiltered well water and rainwater systems, for instance. I drink gallons of the stuff and I'm fine, never better in fact. And yet others come here and start boiling kettles and asking for bottled water because they say it makes them ill.

So I suppose one person might drink flood water and be fine and another drink it and die.

 

[biffvernon]

Yes, Ushy, but have you actually got a back of envelope calculation? Something like 100 000 000 000 000 (a hundred billion) litres of rain fell on the catchment of the Derwent and Cocker upstream of Cockermouth. I reckon that would safely wash away several rats.

 

[Feltwell]

So do you still do that?

No Jon, I couldn't get a job doing that at the time. A shame because I found the subject fascinating. So instead I ended up working in Supply Chain, purchasing for or supplying to the big retailers. I've forgotten most of the theory of hydraulic modelling now, and to be honest I'm too old and have too many commitments to go back to a new-graduate level salary.

 

[Feltwell]

The problem lies less with the number of dead rats than the volume of human excrement which finds its way into flood water as a result of the antiquated sewerage system. In heavy rain this overflows, flooding into the rivers. I'm afraid flood water can be extremenly foul and toxic.

Indeed it can. In a lot of areas the sewerage systems are "combined", i.e. rainwater and foul water goes down the same system. The systems have to be designed with some kind of release valve for the pressure in the event of very heavy rainfall. You know when you're looking at a retaining wall next to a river or often under a bridge, and there is a large round cast-iron "door" set in it? Well that is where, in the event of very heavy rainfall, the excess water that the system cannot cope with comes out. And believe me, having worked on them as part of my degree, a hell of a lot of water can come out of those, containing a lot of not especially pleasant substances as the sewers clean themselves out.

Sewers, unlike fresh water mains of course, rely on gravity. As the path from your house to the treatment works is rarely downhill all the way, pumping stations are required at intervals to raise the level of the sewage before sending it on it's way again.

In a true "flood" situation these pumping stations (which are electric) can fail, so the sewer contents back up and leach out into the floodwaters. Manhole covers can easily come off in these situations, representing a nasty hazard for anyone wading through the floodwaters.

 

[biffvernon]

I'm sure you're right. On the other hand, thinking of the rat-infested floodwaters washing through Cockermouth, I guess worst case scenario is that the sewage farm downstream from Keswick became wrecked and scoured out (it wasn't). All the Keswick poo would then head Cockermouthwards. But most of it would not get there as it has first to go through Basenthwaite. That would add a few orders of magnitude to the dilution.

Putting things in the larger georaphical and temporal perspective, here's today's climate science statement from the Met Office:
http://www.metoffice.gov.uk/corporate/pressoffice/2009/pr20091124a.html

 

[Jon Maine]

I still think that if you have hard floors even if it was shi**y water a hose out with disinfectent would do. I have worked on to many drains and at Glastonbury festival to long to worry about a bit of poo. Dare I say people can be a bit to anal about it. :lol:

 

[Feltwell]

I still think that if you have hard floors even if it was shi**y water a hose out with disinfectent would do. I have worked on to many drains and at Glastonbury festival to long to worry about a bit of poo. Dare I say people can be a bit to anal about it. :lol:

Yep, I agree. You know the vacuum tankers they use at Glastonbury? Last year one of the teams had decorated their's with "Not-So-Solid Crew" :lol:

 

[Jon Maine]

The best one was a year that the dance area was just one big top with a 10000+ capacity and the tent crew didnt put the caps on the king posts, it chucked it down and they had a small lake in the tent. A tanker was diverted from sh*t sucking to suck up this puddle, he got it wrong and put it on blow covering many bystanders with the contents. They all had to be disinfected, injected for hep whichever one it is and their clothes replaced !! :lol: :lol:

 

[Flyfisher]

FF junior regularly uses the National Whitewater Sports Centre at Holme Pierrepont just outside Nottingham. The course is fed from the Trent and when there is heavy rainfall in the vicinity one or more upstream treatment plants 'overflow' into the river as described by Feltwell. In some cases the whitewater course is closed for a while. Despite the dilution factor, 'Trent Belly' is a well-known condition among users of the course and many drink copious quantities of coca-cola as a precaution.

Fortunately, FF junior has never suffered from Trent Belly, something I attribute to a nasty bout of Campylobacter infection he contracted at about nine months old. I reckon this gave his immune system a boost because he's never really been ill since then and doesn't seem to be allergic to anything like so many kids these days.

 

[DaveBrigg]

I thought the health problems at Holme Pierrepont had been traced back to a dead cow trapped below water in one of the sluices, although that was a few years ago.
I wonder if there are different types of flooding which produce different degrees of pollution. In Hull, which is fairly flat, densely populated and close to sea level, the flooding caused sewers to back-up, popping inspection chamber covers in many gardens; bad news if the water then exits through the house. The water stayed for days in some areas. The flood in Cockermouth seems to have been passing through, which caused more structural damage but possibly less contamination.

 

[philpjuk100]

I drank a fair portion of the trent which runs at the end of my garden after jumping in when the river was in flood to retrive an experimental "jet" powered dinghy which had broken its launching rope,I never suffered any gut problems but the earache I got from the wife after returning from a couple of miles downstream is still with me!phil.

 

[MdB]

... retrive an experimental "jet" powered dinghy ...

Cool! Tell us more. Pictures?

 

[wobs]

I wonder if there are different types of flooding which produce different degrees of pollution. In Hull, which is fairly flat, densely populated and close to sea level, the flooding caused sewers to back-up, popping inspection chamber covers in many gardens; bad news if the water then exits through the house. The water stayed for days in some areas. The flood in Cockermouth seems to have been passing through, which caused more structural damage but possibly less contamination.

It was of course a different type of flooding that hit Hull. The water was not particularly smelly in a sewage kind of way, although there were cases of chav kids getting ill from playing in flood water. Naturally, the mothers were on Look North complaining that their little darlings had actually faced the consequences of doing something stupid, but such is life.

Its not just human sewage that contaminates flood water, but in some areas, agricultural and industrial properties can cause all sorts issues. Its really a matter of you don't know whats in the water, rather than "it will be contaminated with s***".

Infact, when I used to sample water from industry, water companies, farms, rivers, beaches etc, the worst water qualities could be expected when large amounts of rainfall washed out muck from all the places above. The idea that flooding dilutes contaminants has rarely been realised, even when an area is totally flooded.

Even if the dilution is significent overall, you don't know :
a. How much dilution has actually occured overall
b. How much harmful material has been washed up into your area
c. How diluted the bit that has reached you is, as the dilution is unlikely to be homogenous

Best to assume the worst I'd say until you know more.

 

[biffvernon]

The idea that flooding dilutes contaminants has rarely been realised, even when an area is totally flooded.

Indeed. And as we know, last weekend's pehenomenon was the rare event. Did you ever see a hundred billion litre flood?

 

[wobs]

The idea that flooding dilutes contaminants has rarely been realised, even when an area is totally flooded.

Indeed. And as we know, last weekend's pehenomenon was the rare event. Did you ever see a hundred billion litre flood?

About 400 million tonnes of water fell across East Yorkshire, South Yorkshire and West Yorkshire in the 2007 floods.

The point is biff is that I have never seen any reliable corolation between flood volume, and contaminants, as there are so many other factors. As such, you cannot say that said flood water would be sufficiently free of contaminants.

I've seen enough floods, and taken samples of the water to know that you cannot predict such things just by observing the volume of water that has fallen.