[TowerTalk] Drain Pipe Passing Thru Tower Foundation

Wed Jan 15 18:00:24 EST 2014

On 1/15/2014 8:24 AM, Brian Amos wrote:
> Not wrong :). I have a bit of experience in the matter.  I have seen
> structures fail from a leaky unpressurized sewer pipe that was fine when
> they built it. The top 1.5 feet will provide so little lateral support that
> it really not matter. If you do leave it in place keep in mind that you are
> taking on greater risk. My experience as a foundation engineer says move
> it.
I would think that with a 1.5' arm that there would be much more 
leverage/strain on the area of the pipe than the lower portion of the 
base.  Also as it presents a discontinuity in the concrete, you'd 
subtract the area used by the pipe from the base area/footprint.

Either way, I agree with moving the pipe

73

Roger (K8RI)

> I come across this situation all the time. Anytime someone wants to build
> an addition or where there used to be a structure I tell them specifically
> to move or remove any utility that is within the footprint of the
> foundation. The only caveat is anything larger than 6 inches they can
> abandon and fill completely with 500 psi grout. Its nearly impossible to
> fill anything smaller with a sufficiently strong grout.
>
> I can think of at least 100 different cases where a structure has sustained
> significant damage from a utility that broke because of an imposed
> foundation load which I have personally been involved with. If you do leave
> it in place the foam could compress and break any plastic pipe. I have seen
> that one too. Just ask the guy in carefree arizona who spent 500k on a
> brand new house and the water line broke where they put it "through" the
> foundation for his kitchen island sink. They wrapped it in foam insulation
> which compressed as the foundation settled and then the pipe broke. 34k
> gallons of water into the subgrade. Water is expensive in az. So was fixing
> the foundation that settled 3 inches and the slab that lifted up 2 inches.
> Over 100k all said and done. That is an extreme case.
>
> I have tons of horror stories. I only hear about the failures so there may
> be many successful installations with pipes through the foundation I am not
> aware of. Do what you want. Just know that I would not put my stamp on any
> document allowing someone to pour a foundation with an active wet utility
> running through it. Abandoned and grouted maybe. But not active. And I have
> never met a soils or foundation engineer who would. There is too much risk.
>
> If it were my tower I would move it.
> Brian
> KF7OVD
> On Jan 14, 2014 12:23 PM, "David Gilbert" <xdavid at cis-broadband.com> wrote:
>
>> Wrong.  No way water that isn't under pressure (it's a passive drain pipe)
>> is going to make the soil around his foundation any wetter than it would
>> normally get being only 1.5 feet below the surface.
>>
>> KA5M should do what G4ZTR says ... wrap the drain pipe with something
>> forgiving (the thin foil-backed foam you can get at Lowes or Home Depot for
>> insulating duct work is cheap and would work fine) and just pour the
>> concrete around it.  That would be MUCH better than tearing up the soil
>> around the foundation.
>>
>> Dave   AB7E
>>
>>
>> On 1/14/2014 11:48 AM, Brian Amos wrote:
>>
>>> Move the pipe. If it were to ever leak you would have a leaning tower.
>>>
>>> Brian
>>> KF7OVD
>>> On Jan 14, 2014 11:42 AM, "John Lemay" <john at carltonhouse.eclipse.co.uk>
>>> wrote:
>>>
>>>   Marsh
>>>> The answer to your question is neither !
>>>>
>>>> No need to relocate the drain, but don't pour concrete directly around it
>>>> either. What you should do is surround the exposed pipe with a firm but
>>>> compressible material, and then pour the concrete. The material could be
>>>> a
>>>> dense foam for instance. Alternatively get a piece of larger plastic
>>>> pipe,
>>>> split it lengthways and place it around your drain with some spacers.
>>>>
>>>> The intention is to isolate the drain from small movements in your
>>>> concrete
>>>> base. Also, if you need to replace the drain at a later date, it will be
>>>> much easier.
>>>>
>>>> This is what I would do in a domestic situation. I'm assuming your
>>>> building
>>>> codes in the US don't have a specific requirement.
>>>>
>>>> John G4ZTR
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
>>>> Marsh
>>>> Stewart
>>>> Sent: 14 January 2014 16:52
>>>> To: towertalk at contesting.com
>>>> Subject: [TowerTalk] Drain Pipe Passing Thru Tower Foundation
>>>>
>>>> I'm installing a base foundation for a US Towers HDX-555. The base will
>>>> be
>>>> 5' X 5' X 7.25' per specs. The rebar will be per specs. Concrete will be
>>>> 4000psi in 28 days. The soil is moist, very firm, and no water is seeping
>>>> into the hole. After excavation began, I found a 6" white PVC drain pipe
>>>> (rainwater run-off drainage, not sewer) that runs across one corner. The
>>>> drain pipe is about 1.5' below grade and runs at about a 30-degree angle
>>>> across one corner. Total length of pipe exposed (in the base foundation)
>>>> is
>>>> about 4'. The rebar "cage" can be built per specs around the pipe. The
>>>> pipe
>>>> can be relocated, but it will require considerable extra digging and the
>>>> soil around the affected corner will no longer be undisturbed.
>>>>
>>>> Should I relocate the drain pipe or pour concrete around it?
>>>>
>>>> Marsh, KA5M
>>>>
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