Any geologists in the house?

[gooseflight]

Need a location. Is it by any chance reclaimed ground?

[njtimber]

Pore pressure in the lower greensand layer ,save yourself a fortune on failed projects and talk to a hydrogeologist, they will need a grid reference . Pm me if you want Helens number she is one of the best you will find by a mile. Nick

[difflock]

Is Greensand green cos of the unoxidised Fe therin, cos I saw traces of "spa" in one of the shots, i.e. oxodized iron="rust"

m

[aspenarb]

Cheers NJ I think thats a good place to start and I will give Helen a call. As others have suggested we need to get the grid reference, identify and locate the source . Without some expert help here we could end up digging around all over the place. I was there today looking at some of the spoils the lads have been levelling out from other excavations on site , there seems to be a mixture of claggy grey clay/sandy gear in the mix. For sure its an underground source but whether its an underground stream, running sand or springs is beyond me.

 

Bob

[aspenarb]

Is Greensand green cos of the unoxidised Fe therin, cos I saw traces of "spa" in one of the shots, i.e. oxodized iron="rust"

m

 

I will dig out one of the soft spots Marcus and see what`s lurking below

 

Bob

[njtimber]

I'm not a geologist, but I believe that greensand is green due to unoxodised iron ,when it reaches the surface it oxidises and turns brown. If water passes through it under ground this will also oxidise it. You get upper greensand and lower greensand , the lower greensand tends to be more silty and more grey in colour.

[drinksloe]

Is there no proper old school agricultural drainers near u?

 

Most old drainer folk esp from that area would probably have a good idea wot it is and best way to fix it without any need for fancy hydrologists etc.

 

Got a couple of old guys in my area that seem to have xray vison there that good at spotting/guessing where the draind run before they dig down to them.

[difflock]

Wot "e" said above

[openspaceman]

I'm not a geologist, but I believe that greensand is green due to unoxodised iron ,when it reaches the surface it oxidises and turns brown. If water passes through it under ground this will also oxidise it. You get upper greensand and lower greensand , the lower greensand tends to be more silty and more grey in colour.

 

Yes it's the change in state from ferrous to ferric salts. In this area of Bagshot sands (lower greensand series I think) the streams run orange from a bacteria that lives off the ferrous salts and takes on the rusty colour as the ferric salts are excreted.

 

Wet patches like Bob describes aren't unusual after the hydrology has changed which can be caused by something simple like circus trucks arriving in wet weather. I made the mistake of driving the County across such a field where I had previously made hay and bellied out in a few yards.

[njtimber]

Is there no proper old school agricultural drainers near u?

 

Most old drainer folk esp from that area would probably have a good idea wot it is and best way to fix it without any need for fancy hydrologists etc.

 

Got a couple of old guys in my area that seem to have xray vison there that good at spotting/guessing where the draind run before they dig down to them.

 

Firstly a hydrologist is completely different from a hydrogeologist ,and if the problem occurs in several places and is due to pore pressure digging a drain will probably achieve nothing except denting your bank balance and upsetting your client. And as for spotting and guessing ,would you hire in expensive equipment on a guess ? Because you could soon make yourself look a right pratt. As for those old guys are you sure they are spotting and guessing you might find they have done their homework before coming on site,after all no point getting older if you don't get wiser,and a wise man never gives away the secret of his wisdom.