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Billingsley-CS080321 .....~......i.............. =i= HaIff Associates, Inc. 1201 North Bowser Road Richardson, Texas 75071 (214) 346-6200 Fax (214) 739-0095 ENGINEERS ARCHITECTS SCIENTISTS PLANNERS SURVEYORS LETTER OF TRANSMITTAL C3-21-08 Afip,:15 IN TO: Michael Garza, E.I.T. City of Coppell Engineering Dept 255 Parkway Blvd. Coppell, TX 75019 DATE: 03/21/08 AVO: 23186 FROM: Brandon A. Luedke, E.I.T. Emai/: bluedke@halff.com PROJECT: Billingsley 156+ ac Tract Retail Cell- Phase II Change order [8] Plans D D Under separate cover via _ the following: D Drawings D Specifications WE ARE SENDING YOU D Shop Drawings [8] Copy of letter [8] ATTACHED D Prints D Other: THESE ARE TRANSMITTED as checked below: [8] For approval D Approval as submitted D For your use D Approved as noted [8] As requested D Returned for corrections D For review/comment D Other: D Resubmit _ copies for approval D Submit _ copies for distribution D Return _ corrected prints ITEMS SENT: - 6 Copies of full size sets (24"x36") of Retail Cell Phase II Floodplain Reclamation Plans signed and sealed for City approval dated 3/20/07; - 1 Copy of Memo dated 3/20/08 responding to City comments from 2/22/08. COMMENTS: Michael, We've addressed your comments as requested for approval. Please let us know when the plans have been stamped for approval. Call me 214.217.6648 or David Littleton 214.346.6213 if you have any questions. Thanks! SIGNED: Brandon A. Luedke COPIES: [8] FILE [8] OWNER D CONTRACTOR ./' ....~..t-(,./ L. ?' /1 l...-_- T i\..--C.~C2 ' 6-'E\ III HALFF ... 1201 North Bowser Road Richardson, Texas 75081 (214) 346-6200 Fax (214) 739-0095 MEMORANDUM TO: Mr. Michael Garza, E.I.T City of Coppell Engineering Department DATE: March 20, 2008 CC: Mr. Jim Pritchard, Pritchard Associates CC: Mr. Bill Walker, Billingsley Co. EMAIL: Brandon A. Luedke, E.I.T. AVO: 23186 Billingsley Tract bluedke@halff.com Irving, Dallas, Coppell, Texas Billingsley 158+ Acre Tract - Retail Cell Phase II Construction Plans FROM: SUBJECT: Halff Associates has received the City comments dated February 22, 2008 for the subject project and we offer the following responses: City of CODDell comment: 1 . The easement for the storm drain should be 20'. Hal" Associates res/Jonse: 1. Easement revised to 20' width. Revised easement description and exhibit will be e-mailed to you early next week City of COD Dell comment: 2. Has TXU approved the outfall in their easement? Hal" Associates res/Jonse: 2. Drainage outfall structure and grading has been removed from TXU/Oncor Raw. City of CODDell comment: 3. How does the outfall drain properly with the flow line lower than the existing grade? We are concerned that the possible standing water will be an issue with the business owners and they will blame the city. Hal" Associates res/Jonse: 3. During and after a rainfall event, there is the potential for up to 1', more or less, of standing water at the 48" RCP outfall before spilling into the wetland in TXU/Oncor Raw. The rip rap (non- grouted) at outfall should help with infiltration of water over a short period of time to minimize standing water. If ponding becomes an issue between the time of completed construction of pad site and design of future site development, other solutions could be explored at that time. The owner is aware of this issue. Also, in response to your note on C3.01 which says "outfall is 4' below this elevation?".. ... the spot elevation you're referring to is on top of an existing culvert crossing, so the flow line of the channel is much lower. The contours were generated from an aerial and apparently did not pick up the culvert, but I've seen it in the field.. .its corrugated metal pipe. In response to another comment on C3.01 which says "is 12" adequate?". ...the pipes are designed only to relieve any potential ponding, they were not designed for a particular conveyance flow. To elaborate, the swales from Phase I & 11 are not connected because the U.S. Corps of Engineers has identified the area between them as wetlands. We've obtained a Nationwide 404 Permit from the Corps to construct the pad site and mitigate as outlined in the Permit. Therefore, we had to design the downstream end of the swale with an embankment to match existing and minimize impacts to the wetlands. I :\23000s\23186\admin\memo\Mm 03-20-08 Coppell.doc