Structural Engineering: Re: Push piers foundation systems

Gordon, Harold- Thanks for the advice! AB Chance is 2 hours away and may not travel this far, which could limit my options. But I will check and cross my fingers from there! Good comments about taking a critical look through the warranty. Its pretty vague other than excluding possible damage to utilties, drywall cracking if lifted, etc. Nothing tthat sounds like a trap.

I am suspicious about how many piers they say they need. Certainly more than is necessary but that can be corrected.

Jim

From: Gordon Goodell <GordonGoodell@harmonydesigninc.com>
To: seaint@seaint.org
Sent: Thursday, April 30, 2009 11:34:37 AM
Subject: RE: Push piers foundation systems

Jim,

PDCA, the Pile Driving Contractor's Association, likes to say that driven piles are tested piles. This is true. You stop driving when a proof load, your load times some safety factor, is reached. The geotech is useful if you want to know in advance how far you'll have to drive them.

Another option you might want to check is helical piers, which attain higher bearing much faster (shallower) than piles. They can be driven (by a certified contractor) with the pto for a backhoe or even a Bobcat. The one I've used (with excellent results) is AB Chance. Find a local distributor on their website: www.abchance.com

regards,

Gordon Goodell

From: Jim Wilson [mailto:wilsonengineers@yahoo.com]
Sent: Thursday, April 30, 2009 6:53 AM
To: seaint@seaint.org
Subject: Push piers foundation systems

Is anyone familiar with the Push Pier System provided by Foundation Supportworks, or similar products for that matter? I have settlement under a portion of my garage that needs to be addressed. This is a simple end-bearing pipe pier hydrolically pushed down to bearing.

The system does carry a 25-year warranty and looks to be well designed. I don't know if there are any particular risks or gotchas with installing these systems. They say they usually hit bearing in 20-30 feet but I realize that is a big unknown. There isn't much online to read about these that isn't promotional. I did find one link to a discussion where they warned about the thickness and grade of the steel.

The contractor does not suggest that I hire a geotech to do a study - am I adding a lot of risk by not doing so? It is only a light single-story structure.

They do not suggest the helical pier, either. Soils are sandy gravel. They are not expansive. The upper layer under the foundation may have been fill but I don't know for sure. Settlement is arguably active - notable additional recent movement has been attributed to vibration from paving our driveway last year. Garage is 20 years old and has dropped maybe 2" overall.

Jim Wilson, PE

Stroudsburg, PA