Rohn 25G and base question

[WX4SNO]

Hello everyone,

I recently bought a gently-used 40' Rohn 25G tower that was originally installed back in the 1990's by a telephone/internet company. The tower had about 10-12 different antennas on it when the company went under and left it to the guy I bought it from; it had been un-guyed and stood up to some strong wind events and ice/snow storms in the WV mountains. I'm planning on installing only 30' of it without guy wires (don't have the space) and it will only have a small 144/440 vertical, a scanner antenna, and a weather station anemometer attached. I'm also going to buy the 5' base section (R-SB25G5). I don't plan on climbing the tower, either walking it up to install it or using a scissor-lift to put the sections into place.

My question is, what would you all recommend for the size of the concrete base? I found a reference online from Rohn that suggest I use a 6x6x4 concrete slab with the base section submerged inside that. Is this overkill? We have hard soil, made up of bits and pieces of sandstone and quartz. I'm just curious if a 3x3x3 or a 3x3x4 concrete base would suffice?

Thanks in advance!
WX4SNO

 

[shortride]

I've had a 72' tall Rohn guyed 25G up since 1995. I had a custom base plate made for laying the tower down if and when I need to. The base plate is anchored in a 3' x 3' of concrete tapered to 4' at the bottom of the hole and has shown no signs of not be adequate for the installation. I'm sure the tower people know what they are talking about with their recommendations. Some of it has to do with the type of soil you have at your location I would imagine. Although you're only going up 30' with the tower, you need to consider that the wind will be working on trying to move the base installation around. You may be able to get buy with less concrete but I think it would be a good idea to go a little deeper.

Sometimes, what sounds like overkill may not be as much as it seems.

 

[LtDoc]

The typical foundation for a towert by the manufacturer is usually a 'minimum' type thingy with some 'safety factor' built into it. Most of the time it may sound like 'over-kill', but what's wrong with that? It's always better to 'over-do' than 'under-do'. 'Cuz 're-doing' is always twice as expensive...
- 'Doc