[RE-wrenches] helical screw piers

[John Raynes]

What kind of post-post horizontal tolerancing can you hold with those 
things, and how is it adjusted or compensated for while driving 
in?  Usually at least one of the two horizontal surface coordinates 
has a reasonably tight alignment tolerance in my experience.

They look like a great idea, although one advantage of concrete is 
you have lots of time to tweak the post alignments if necessary while 
the concrete sets.  I would think a helical screw would be prone to 
walking just a little, unless the drive apparatus is extremely well-anchored.

John Raynes
RE Solar
Torrey, UT


At 08:45 AM 1/26/2009, you wrote:

>We have also used the local franchisee of TechnoMetal Posts for many 
>jobs that are ground mounts.
>Around $250 per post is what we paid also.
>They were in and out on our last job in 2 days, but their machine 
>did break down for a while. They placed 32 posts in 2 arrays for a 
>12.6 kWp array (60 modules).
>We marked the 4 corners of each array & told them how far apart to 
>place the posts & off they went. Marked, drove, cut off those too 
>high & welded on extensions to those too short, then ground the 
>welds & painted.
>
>We also topped them with Unirac U-LA racking and it lined up well.
>
>-Glenn
>
>From: re-wrenches-bounces at lists.re-wrenches.org 
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Larry Brown
>Sent: Monday, January 26, 2009 7:24 AM
>To: info at asappower.com; RE-wrenches
>Subject: Re: [RE-wrenches] helical screw piers
>
>Wrenches,
>We used a company called techno Metal Post  ( 
><http://www.technometalpost.com>www.technometalpost.com ) I believe 
>it is a franchise arrangement with the main company in Canada. Here 
>is a business opportunity if a franchise does not exist in your community.
>They are screwed into the ground while hydraulic pressure is 
>applied. We received a stamped engineering report after completion 
>that identified how many posts were set,  to what depth and how much 
>hydraulic pressure had been applied for load bearing capacity
>It requires a special unit designed for this purpose
>We set 8 posts in 2 rows of 4 and then attached a UniRac U-LA Ground 
>Mount racking system for 28 Sanyo 200's
>The posts in this case were 2" schedule 40 galvanized steel pipe 
>ready for the UniRac mounting system
>They also shot the elevation and cut each pipe to the proper height 
>so that the relationship between the front row of pipes and the back 
>row of pipes was set to receive the racking system and then the 
>mounting rails would be at latitude for this site.  We supplied the 
>heights that were required.
>Many other uses for these screw piers.  Pictures on their website
>
>Larry
>
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