Garage foundation design - borehole plant ducting

[Kelvin]

Hi

 

Was supposed to get my SE stuff back today. Instead I got a delay notification email and won’t get it until 23/9 so 7 weeks since they got the drawings. They also said they need a detailed ducting design for the borehole plant which will be in the garage. It’s literally 4 ducts that’ll extend 1m or so from under the foundation - water in, water out, waste out (might need a water softener), and power in. In addition I’ll need to add a data duct and another couple of power ducts. I’ve marked on the drawing where the plant will go.
 

Am I missing something how much more detail do they need to add it to their foundation design for the warrant drawings? Can someone with a borehole share any drawings they have? 

[Gus Potter]

You could try sending them something like this, have sketched a couple of alternative cross sections, put your own dimensions on. Also mark on the plan drawing where the ducts cross the founds, hopefully not near the corner of the founds. The SE will maybe come back with a change in the bedding etc but they probably want to know where the soft spot will be from the ducts and how much the may need to bridge over. Pity they did not ask for the info sooner.

 

 

[Kelvin]

Thank you. I would expect the SE to do that bit of it as why would it be that different from the ducting entering the house? 

[Gus Potter]

28 minutes ago, Kelvin said:

Thank you. I would expect the SE to do that bit of it as why would it be that different from the ducting entering the house? 

No reason really.

 

A caveat though. When you create duct routes or routes for drains under founds you need to just check the ground water flow and the type of soil. What we want to avoid is creating a route where water can flow in a trench under the founds at a significant rate. A big risk is in say soft fine sand and fine silts as the flow of water can wash away the fines and reduce the bearing capacity of the soil around the trench. Some amount of seepage is normally ok.

 

If you take say a power cable coming into the house it normally has a hockey stick.. a short duct but the rest of the cable is normaly just backfilled with normal soil.

 

That said the cynical may say it does look a bit like the SE is kicking the can down the road and buying time.

 

 

[Kelvin]

I managed to speak to the guy supplying my plant equipment a few minutes ago. He said in 30 years he’s never been asked to design the ducting and he does the Crown estate up here etc. I think you’re right on buying time. All a bit annoying. This SE has cost me a total of 12 weeks delay since March. 

[Nickfromwales]

8 minutes ago, Kelvin said:

I managed to speak to the guy supplying my plant equipment a few minutes ago. He said in 30 years he’s never been asked to design the ducting and he does the Crown estate up here etc. I think you’re right on buying time. All a bit annoying. This SE has cost me a total of 12 weeks delay since March. 

Time to get him to justify, or get rid? Stinks of too used to them going unchallenged.

[Kelvin]

20 minutes ago, Nickfromwales said:

Time to get him to justify, or get rid? Stinks of too used to them going unchallenged.

Borehole guy or SE? 

[Nickfromwales]

8 minutes ago, Kelvin said:

Borehole guy or SE? 

SE, apologies. That’s a black and white scenario so shouldn’t attract such complications or elongation. At the very least they should have identified any “issues” and requested that you mitigate?

I provide bespoke slab penetrations details on each of my clients new builds, and have never seen this level of ‘confusion’ tbh. I sometimes get a nudge when we’re close to steels in ring-beams, but that’s usually resolved in a day.

Too many people being over zealous with “covering their arses” these days, and always at the clients expense.
 

You’re not building in Gravenhill are you? In-house BCO’s there are “interesting characters”………😕