Ron, Attached is the design on a detention pond that works with minimal changes to the plans. I have also attached the detention pond calcs and a detail for the restrictor plate. Additionally, I have attached an inlet that will work in this application. I of course could not capture all of the area without a significant modification of the plans, but this will capture a majority of the excess. I used a planimeter to arrive at the areas and runoff coefficients. They may be slightly off, but should be pretty accurate. Also, I believe that a time of concentration of 10 minutes for both pre and post development is more reasonable considering the size of area. It is up to Nancy if she wants to use it, but this should be all that you require. If there is anything that I left out, please let me know. Thanks, Clay Barnett, P.E. Town Engineer Town of Addison 16801 Westgrove Drive Addison, TX 75001-2818 Office: (972) 450-2857 From: Ron King [mailto:RGK@freese.com] Sent: Monday, January 10, 2011 4:11 PM To: Nancy Cline; Clay Barnett Cc: Ron King Subject: EST site runoff Nancy, Clay: As you requested at our latest meeting, I have taken a second look at the pre- and proposed runoff from the tank site. For the existing conditions, I used a C-value of 0.30. For proposed conditions, I determined a weighted C-value based upon grassed, pavement, and tank areas, and determined a C-value of 0.60. For Area A-1 that eventually goes down to Beltline Road, this resulted in an existing conditions flow of 2.32 cfs and proposed flow of 4.64 cfs, representing an increase in flow of 2.32 cfs. As a preliminary thought based upon the above, it is likely the increase in flow won’t create an significant impact on the storm drain system downstream. Please let me know if you have any additional feedback or questions on this. Thanks, Ron Please consider the environment before printing this message. ________________________________ This electronic mail message is intended exclusively for the individual or entity to which it is addressed. This message, together with any attachment, may contain the sender's organization's confidential and privileged information. The recipient is hereby notified to treat the information as confidential and privileged and to not disclose or use the information except as authorized by sender's organization. Any unauthorized review, printing, retention, copying, disclosure, distribution, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this message in error, please immediately contact the sender by reply email and delete all copies of the material from any computer. Thank you for your cooperation.