Chris, Please review and send any comments you have. Thanks, Clay Barnett, P.E. Town Engineer Town of Addison 16801 Westgrove Drive Addison, TX 75001-2818 Office: (972) 450-2857 From: Lynn Kadleck [mailto:lkadleck@verizon.net] Sent: Saturday, January 29, 2011 2:48 PM To: Clay Barnett Cc: Chris Robinson; Bill Leggett; Ron Frederick Subject: Million Air Phase 2 Clay, Attached is a copy of the revised Drainage Area Map with new calculations and a spreadsheet for the Detention and Orifice calculations. I used the one furnished from Chris Robinson and revised it to reflect the added area between the edge of the taxiway and the lease line, which is now being paved. Basically, the existing discharge from the unimproved area of 3.01 acres is 6.8 cfs. The undetained part is 3.1 cfs thereby reducing the allowed release to 3.7 cfs. The allowed pass through the detention is 4.3 cfs resulting in a total allowed release of 8.1 cfs (after round off). I also lowered the starting hydraulic grade at the connection to the existing inlet. It is now the inside top of the new 24" pipe. This produced a detention volume of 24,046 cubic feet and an orifice opening size of 13.7 inches. Please have Chris review this information to see if he agrees and contact me with any questions or comments. Regards, L. Lynn Kadleck, PE, RPLS Kadleck & Associates 555 Republic Drive, Suite 115 Plano, Texas 75074 972-881-0771 lkadleck@verizon.net