August 24, 2021

Small Cell Installations & Helical Piles

Small Cell Installations & Helical Piles

Small Cell Installations & Helical Piles

Technician installing foundation of solar panel with helical piles. Engineer setting frame fo photovoltaic panels.

In the world of wireless telecommunications and small cell deployment, you might come across the use of helical pile foundations. These are nothing new and were invented in the 1830s by an Irish Engineer, Alexander Mitchell. He was a civil engineer and developed the design to stabilize structures built in coastal sands. Since then the technology has advanced and the use of helical piles for foundations is common practice.

So why use helical piles for a Small Cell pole installation?

Well depending on your deployment environment, it is a very fast way to install a foundation and it gives you the ability to replace an existing pole and foundation the same day.

So why not install helical piles for all of my Small Cell foundations?

Good question. The answer is that depending on your location helical piles might not be the right choice. Typically a small cell foundation will require at least three helical piles and these would need to be deployed to a depth of approx. 12ft for a generic small cell pole depending on loading and soil conditions. With these depths, you run the risk of hitting underground utilities.

Can’t we use GPR to avoid hitting underground utilities?

Yes, you can scan the ground using GPR but depending on the ground conditions the depth of penetration is affected. In layman’s terms, GPR uses the transmission and reflection of high-frequency electromagnetic waves in the soil. The penetration depth of GPR measurements is affected by the electrical conductivity of the soil. A good penetration depth of up to about 30ft can be achieved in dry sandy soils or massive dry materials such as granite and limestone. As the conductivity increases, penetration depth decreases because the electromagnetic energy is more quickly dissipated into heat, causing a loss in signal strength at depth. In highly conductive soils, such as those with large amounts of clay, water, and/or salt, penetration depth can be reduced to less than 2ft.

So when should I use helical piles?

Helical piles are a good tool and solution in the right environment. If you are in an urban setting where you have extensive underground utilities, subterranean basements, drainage culverts, and subways you should use caution before deploying helical piles. For example, in a recent Small Cell deployment in Boston, MA GPR was not effective to review underground utilities beyond a few feet and therefore we couldn’t locate the utilities and ensure that deployment of a helical pile wouldn’t damage existing underground utilities or structures. Given this situation, our team of professional engineers developed custom shallow concrete matt foundations for each pole as these suited the environmental constraints better and mitigated all risks. In the right setting with the right ground conditions, a helical pile solution might be the right option but helical piles are just another tool in the engineer’s tool belt. Also with rapid setting concrete, the time difference between a custom concrete matt or pier foundation compared to a helical pile solution is negligible.

I would like to know more about helical pile foundations and your custom small cell foundation solutions – can you help me?

Absolutely. KMB has completed the design of over 18,000 Small Cell installations in 48 states across the USA. We can share typical helical pile and concrete matt foundation designs which our professional engineers can custom to meet your needs. We are licensed in all 50 states in the USA and in Europe to enable us to serve your project needs no matter where they are.
For more information please email info@kmbdg.com or head to our website https://www.kmbdg.com/ 

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