FYI… I talked to Brian and he shares Bill’s concerns.

Clay Barnett, P.E.

Town Engineer

Town of Addison

16801 Westgrove Drive

Addison, TX 75001-2818

Office: (972) 450-2857

 <http://www.addisongreen.info/> 

 

From: Bill Campbell [mailto:owcampbell@kleinfelder.com] 
Sent: Thursday, July 15, 2010 3:03 PM
To: Clay Barnett
Cc: Noel Janacek; Wade Geistweidt
Subject: Fwd: RE: FW: Response to Construction Submittals No. 8 for project "Vitruvian Infrastructure Phase 1C Park"

 

Clay-

 

Here are our engineer's response to Olden's response on the soil nail walls.  The big concern is that if they don't put a drain behind the wall, it could lead to a long-term performance
issue.  It is up to the Town of Addison how far you want to push this.

 

 

Bill Campbell, Jr., P.E.
N. Texas/Oklahoma Business Unit Leader
2035 Central Circle #110
McKinney, TX 75069

o| 972.562.4677
c| 214.837.4476
f| 972.542.4366


 <http://www.kleinfelder.com/> 

>>> Noel Janacek 7/12/2010 7:03 PM >>>

My thoughts for responses.  Please QC before passing along.

 

A1.  Does this reduction in capacity change the nail spacing?  Also, now that the load tests have been performed, have these values been verified?

 

A2.  Please provide load test results. (done)

 

A3.  While the walls have apparently been design to account for hydrostatic pressure, most wall designs provide drainage as water tends to be the root cause of poor wall performance
in many cases.  As these walls are at the bottom of a slope adjacent to water that will likely fluctuate, please provide examples of walls that have performed long term without drainage.
 

 

A. Noel W. Janacek, PE
Consulting Engineer - Kleinfelder

We have reviewed the Olden submittal dated May 17, 2010 and have the following recommendations:

1. The submittal states that the design is based on Geotel Engineering, Inc.'s report no. E08-130 dated March 6, 2008. A subsequent report E10-129 dated April 22, 2010 should be reviewed
by Olden to verify their design is still valid.  We have reviewed the subsequent report dated April 22, 2010 and the design as submitted is still valid.  The only exception is that the
allowable pullout resistance will be reduced to 600 psf and the DTL for soil nail verification testing will be 14.1 kips with a bond length of 15 feet.  

2. Test results from the load testing described in the submittal should be observed and reviewed on behalf of the Town of Addison by a qualified Geotechnical Engineer registered in the
State of Texas.  The test results will be forwarded to the Town of Addison upon completion.

3. No wall drainage is shown in the submittal. Olden should confirm that hydrostatic pressures were used in design, or adequate drainage should be provided to prevent hydrostatic pressure
from building up behind the wall.  The hydrostatic pressures were accounted for in the design.  

We assume that the CM team will evaluate the geometry of the walls relative to the project plans.

As long as Olden has checked item 1 above, nail installation can proceed up to but not including shotcrete. The other two items need to be addressed prior to shotcreteing. 


B. Brian J. LaFoy, P.E. 
Nathan D. Maier Consulting Engineers, Inc.

My main concern is that I do not see any recommendations in the geotechnical report regarding soil nails so I am unclear as to how the wall was designed without that information (such
as friction values for the soil against pullout, etc). Did Olden assume values? On what basis? Also, there is only one value for lateral pressures to use in the geotechnical report presumeably
for the orginally intended cantilever walls on piers. I would interpret that value for use under yielding conditions with that type of wall. However, the soil-nailed wall in my opinion
is a rigid wall which usually constitutes higher lateral pressures than that for yielding. Finally, it appears the intent of both walls would penetrate the shale, so I assume that end
bearing in the wall is not an issue, but again, that is not specifically addressed in the geotechnical report.
In short, I do not follow the communication trail between Olden and the Geotech so I have questions as to the basis for the shop drawings. I have no concerns with the general methodology
though.

>>> Wade Geistweidt 7/9/2010 4:20 PM >>>

Bill, Marc, & Noel,

 

Here is Olden's response to our questions on the soil nail walls.

 

 

Thanks

 

Wade Geistweidt
Engineering Technician
2035 Central Circle suite 110
McKinney, TX 75069
o| 972.562.4677 
c| 469.576.9951
f | 972.542.4366

 

 
 
Warning: Information provided via electronic media is not guaranteed against
defects including translation and transmission errors. 
 
If the reader is not the intended recipient, you are hereby notified that any
dissemination, distribution or copying of this communication is strictly
prohibited. If you have received this information in error, please notify the
sender immediately.