In short, yes, there are some spacing requirements when it comes to installing a helical pile.
Helical piles must observe the same horizontal spacing requirements that most other end-bearing deep foundation elements must stick to. Currently, the industry standard for this is 3 x diameter and this is measured going from center to center.
For instance, if a lead section has an 8”/10”/12” helix configuration, the minimum spacing it needs will be 3 x 12” = 36” from center to center.
Typically, we try to use the largest helical plate possible.
It is important to note that the minimum spacing requirements for your helical pile really only matters when we are talking about bearing depth where the helical piles are actually contained.
What this means is that if you have multiple piles all under a pile cap but you want to minimize that pile cap area, you can usually just install the helical piles at an angle in order to give you the right amount of separation that you need to have at bearing depth and then the piles can simply be terminated into a smaller footing.