Joel: Here is the fleet mix that is considered in their FAARFIELD pavement design. The concrete thickness is greatly reduced by the strength of the limestone subgrade and aggregate base thickness. If they didn’t remove all the clay soil above the limestone, the concrete thickness would be 10-11 inches. Frank McIllwain, PE Garver From: Jenkinson, Joel [mailto:Joel.Jenkinson@wgint.com] Sent: Tuesday, May 25, 2010 5:08 PM To: McIllwain, Frank O.; John Johnston Cc: jimalbertson@cox.net; Clay Barnett; joel.jenkinson@addisonairport.net; joe.mcanally@addisonairport.net; Nancy Cline Subject: RE: ExecHangar Pavement What is the design aircraft / load rating for this proposed pavement section? Joel Jenkinson Director, Addison Airport main: (972) 392-4850 fax: (972) 788-9334 ________________________________ From: McIllwain, Frank O. [mailto:FOMcIllwain@garverusa.com] Sent: Tuesday, May 25, 2010 4:05 PM To: John Johnston Cc: jimalbertson@cox.net; Clay Barnett; joel.jenkinson@addisonairport.net; joe.mcanally@addisonairport.net; Nancy Cline Subject: RE: ExecHangar Pavement John: On behalf of the Town of Addison, we have no objection to the aircraft apron pavement section of 8 inches of reinforced concrete over a variable thickness (approximately 6-18 inches) of base course over existing limestone. This decision is contingent upon the following: 1) All clay material under the proposed pavement section shall be removed and hauled off site. 2) Laboratory test results that confirm all material used as base course has a CBR value of at least 20. 3) The plans are updated to show the new pavement section. Placement of base course material(s) may not proceed until receipt of the updated plans and base course material test results has been confirmed by the Town of Addison. Frank McIllwain, PE Garver From: John Johnston [mailto:jwjohnston-hja@sbcglobal.net] Sent: Friday, May 21, 2010 11:31 AM To: McIllwain, Frank O. Subject: ExecHangar Pavement Frank - Attached are FAARFIELD analyses intended to represent the minimum value anticipated from the available pulverized material at the site utilized as base. That material is represented as having a CBR of 20 and E determined as 1500 x CBR. A CBR test will be performed on the material to determine its actual CBR level. Grain size distribution also will be determined. The analysis sheets for base thicknesses from 6 inches to 18 inches are attached. Assuming the CBR test gives us a value of 20 or above I will define the final design criteria to allow the owner to proceed. Based on the proposed CBR testing the owner intends to pull up the existing aggregate base and stock pile it on the site. They will also remove and separate the existing clay soil and dispose of it off site, thereby eliminating all expansive soil material down to the weathered limestone. They will then place the existing aggregate base in engineered lifts and the concrete paving per final recommendations. The owner would appreciate your approval of the above procedures, so that he can move forward. Could you please let me know your thoughts at your earliest convenience. Thanks, John John W. Johnston, P.E. Henley-Johnston & Associates, Inc. 235 Morgan Avenue Dallas, Texas 75203-1025 Texas Firm Registration No. F-1238 Phone: 214-941-3808 Fax: 214-943-7645 e-mail: jwjohnston-hja@sbcglobal.net