Eric, Could you help us out with this? Thanks, Clay Barnett, P.E. Town Engineer Town of Addison 16801 Westgrove Drive Addison, TX 75001-2818 Office: (972) 450-2857 -----Original Message----- From: Christiansen, Eric [mailto:echristiansen@halff.com] Sent: Monday, March 22, 2010 12:15 PM To: Clay Barnett Cc: Nancy Cline Subject: Vitruvian Park - Geotechnical Issue Importance: High Clay, There is one issue that came to light late Friday that will require the assistance of the geotechnical engineer. One of our engineers contacted Geotel to discuss lateral soil pressures for the abutment walls. We are trying to reduce the load on our abutment walls by using select or granular fill in lieu of on-site clays. Instead of responding to our question, we were informed that the walls would need to be analyzed for global slope stability. To be fair, the Geotel soil report (at the end of section 6.3) mentions this analysis should be accomplished for slopes greater than 10' or retaining walls bearing on slopes. While our project doesn't meet the description perfectly, it's apparent that we won't be able to get our question answered until Geotel completes some additional analysis. Since the report was written to UDR, it is likely that UDR paid for the report. If that is true, please ask UDR to see that the following items are accomplished: · Global stability analysis of abutments at Ponte, Bella, and the Southern Pedestrian Bridge (as required) · Clarification of the 110 pcf lateral load for retaining walls o Is this an at-rest load for on-site clays (as is assumed)? o Can this be reduced by using select fill or a granular fill? We regret this is being addressed at this stage of the design process, but we didn't anticipate this would become an issue for walls on drilled shafts. Since we don't believe the outcome will significantly affect our design, we will continue to work on the project while we await an answer from Geotel. Should you have any questions or concerns regarding this matter, please feel free to contact me directly. Sincerely, Eric Christiansen Eric S. Christiansen, P.E., SECB, LEED AP Senior Structural Engineer HALFF ASSOCIATES, INC. 1201 North Bowser Road Richardson, Texas 75081 Phone 214-346-6284 Fax 214-739-0095 Cell 972-955-2996 www.halff.com