[TowerTalk] Question altering concrete base dimensions Hygain HG-52SS

[AB2E Darrell]

Greetings All,
I have a question for the gurus, could not find any specific info on this.
The specs in the manual for the Hygain HG-52SS crankup self-supporting tower are 3.5x.3.5x5.5 ft for the concrete in the base.
This is approx 67 cu ft, or roughly 2.5 yards of cement. My water table is high, somewhere around 4ft in places I have done a sample dig.
So long as I keep the same or greater volume of cement, is it OK to modify the dimensions of the base some?
I'm thinking 4X4X4.5ft, this would be 72 cu ft, or almost 2.7 cu yd. I could also easily make it 5x5x4 ft which would be 3.7 cu yd.
So I would be expanding length and width by 6 inches each, and taking 1ft off of the depth of the first scenario, and expanding 1.5ft length and width, and shortening 1.5ft depth on the 2nd scenario.

Any thoughts on this?

73 Darrell AB2E