DR1201-CS131106 t
i
Scott Miller
Consulting
Engineer 'Ii P.O.Box 94529 North Little Rock,AR 72190
I. s Tel:501.374.3546"Fax:501,374.3547 E-mail:segwalis @gmail.com
November 6,2013
Mr. Rodd Brann
SYB Construction Company,Inc.
421 Compton Avenue
Irving,TX 75061
RE: Leveling Pad
Anchor Block Retaining Wall
Creekview Retaining Wall&Roadway Improvements
City of Coppell,TX
Dear Mr.Brann:
I have reviewed Sketch 15.03 and the wall cross-section prepared by Walter P. Moore &
Associates, Inc. dated April 17, 2013. The sketch shows a 4.0—inch thick unreinforced concrete
leveling pad for the retaining wall. Concrete leveling pads, in general, are not preferred by block
manufacturers and engineers for segmental block retaining walls such as the Anchor retaining wall
on this project. Concrete will crack on approximately 10.0 to 20.0 foot intervals concentrating the
movement in the retaining wall face at those cracks,and consequently the movement will be more
evident in the wall face. A compacted TXDOT Flexible Base crushed stone or recycled concrete
is preferable as it will spread the movement out over the entire retaining wall length and the
movement will not be concentrated at any one particular spot(The leveling pad is a non-structural
member and intended only to provide a level,flat surface for the first block course. )
This year alone, I have provided engineering services on over 50 segmental block retaining wall
projects in the State of Texas,and all the commercial projects have been designed with a TXDOT
Flex Base leveling pad. These projects represent over 150,000 square feet of retaining wall in the
State of Texas this year.
In my opinion, the concrete leveling pad is not only unnecessary, but can actually contribute to
concentrated movements in the wall face and the preferable leveling pad for this retaining wall
would be compacted TXDOT Flex Base crushed stone or recycled concrete.
Mr. Rodd I3rann
November 6,2013
Page Two
I appreciate this opportunity to be of continuing service to you and Carma Construction. Should
you have any questions regarding this letter, please do not hesitate to contact me at your
convenience.
Sincerely, of T %
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Sett A. "Sam" Miller,PE i. OTT A. Mtt_tSR S
Principal Sc
SAM/sync � ;;�SSioni
13271,leveling pad