[TowerTalk] FW: Digging a 5'x5'x7' hole in sandy soil

[Michael Tope]

I have some property in the high desert north of Los Angeles that is 
nothing but sand. When I was getting prepared to take delivery of a 40ft 
storage container, a concrete contractor who did some work for me 
recommended that I have the sand packed before bringing an 18 wheeler on 
to the property. The guy who did that work for me was a soil engineer 
who mentioned having just done a hole for a customer's crank-up tower. 
Surface packing to accept a heavy vehicle is pretty straightforward. You 
wet down the area to be packed for a day with sprinklers and then come 
in with a heavy tractor and roll back and forth over the wet sand 
repeatedly to pack it. For building or tower foundations, Sal described 
the procedure, but I forget the specific details.

73, Mike W4EF..........

On 8/14/2013 7:16 PM, Matt wrote:
> Just want to reiterate on advice from N6SJ, AB7E, KK9A, & VE4XT...  get with
> a qualified structural engineer if there is any doubt about the compressive
> strength of the soil you are placing the foundation in.   Sand that
> collapses upon excavation is reason enough to have doubt!   Insufficient
> footing support for the foundation can result in the foundation leaning,
> failing, or overturning at less than design load.
>
> Matt
> KM5VI
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Roger
> (K8RI)
> Sent: Wednesday, August 14, 2013 9:08 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Digging a 5'x5'x7' hole in sandy soil
>
> On 8/13/2013 6:57 PM, jeffhook at comcast.net wrote:
>>
>> To all:
>>
>>
>>
>> I have a used US towers HDX 555 I'm installing .
>>
>> US tower sent me new anchor bolts and a print of foundation and it says
> undisturbed soil and forms can't be left in hole.
>> I live in a sandy area and wonder how others have dug a 5x5x7 hole,
> installed reb ar cage, and filled with concrete, without it caving in?
>>     
> Are these showing up. I never see them.
>
>
> There are times when it is not possible to pour into undisturbed soil. I
> would ask them(US Towers)  specifically what they recommend to use in sand.
> They may recommend a larger base. but you might have to resort to
> commercial, metal forms.  After the pour cures "enough" the forms are
> "pulled" which of course takes some power and maybe the services of a
> contractor.
>
> Because of the unstable soil, I'd want a larger base and as someone else
> suggested, a base specifically for loose sand would resort to the metal
> forms even if I had to hire a contractor.
>
> Where I'm putting up the LM470, the soil should be firm enough to pour
> against the side of the hole (undisturbed soil) but the concrete will need
> to be poured right away.  Even a light rain could cause it to collapse. I
> only have to go 15 to 20 feet West or north and it becomes more of a peat.
> When I dug the holes for the 45G guy anchors, I went back the next morning
> and the NW hole had become about 12 feet across and 1 foot deep.
>
>
> 73
>
> Roger (K8RI)
>> Thanks - Jeff
>>
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