Loading...
Coppell/121 Off Pk-CS040308COl'FELL March 8, 2004 Mr. Konstantine Bakintas, P.E. BHB Engineering & Surveying 309 W Seventh St, Suite 500 Fort Worth, TX 76102 RE: Coppell / 121 Business Park ~ar Mr: Bak~ntas: The City of Coppell has reviexved the plans submitted for Coppell/121 Business Park and we have the following comments to offer: General Comments - 1. The arrangement of the sheets is confusing. Please consolidate the site-specific sheets in one area, deceleration lane in another area and the offsite water in a separate area. 2. The Cover Sheet states that SH 121 is in Bedford, Texas. Please correct it to say Coppe]l, Texas. Final Plat- 1. You show several easements as being offsite and per separate instrument. The City of Coppell needs to have signed and executed copies of those easements prior to approval of these plans. Drainage Area Map sheet - 1. The photograph used as the basis of the drainage area map is difficult to read, and the offsite contours and drainage patterns are impossible to make out. 2. The storm drain is called out on this sheet as 42", on other sheets it is called 48". 3. Please include calculations for the 4'X4' grate inlet proposed within the TxDOT right-of- way. I assume these computations use the TxDOT methodology for drainage, but they need to be reviewed and approved by TxDOT. Site Development Plan sheet - 1. Show the City of Lewisville's 27" sanitary sewer that is within the TxDOT right-of-way that crosses this work area. Site Paving & Dimensional Plan - 1. No comments. Deceleration Lane Paving & Dimensional Plan - 1. The details of all construction within the state right-of-way, specifically the construction of the deceleration lane, needs to be done in accordance with and approved by TxDOT. 2. In addition, the stamped and stained concrete needs to be at least 8' in width and be located at the property line. It can be extended as far back as desired. Deceleration Lane Striping & Signage Plan - 1. All striping and signage within the TxDOT right-of-way needs to be approved by TxDOT. Traffic Control Plan - 1. Again, traffic control within the TxDOT right-of-way needs to be reviewed and approved by TxDOT. Grading & Drainage Plan - 1. You call out to construct a standard 5' 3torm drain manhole on a 48" pipe. That does not meet our standards for size. It should be pipe size plus two feet minimum for the manhole size. 2. At the outfall of the 48" pipe you show a 48" headwall and Type B riprap. Give an indication of quantity of riprap to be used. Deceleration Grading & Drainage Plan - 1. While this needs to be reviewed and approved by TxDOT as well, you need to consider the curb inlets. While looking at a profile of the drive, it appears that your deceleration lane will be at a 4% slope from the existing edge of pavement or gutter elevation up the decel lane. You will have difficulty with your storm water collection if you put a positive slope where the flow line of the proposed inlets will be higher than the existing inlets. Storm Drain "A" Plan & Profile - 1. I would like to see this plan in one section, with an orientation that makes it continuous rather than being split in two. 2. Where you show to com~ect to the existing 42" storm drain with a 48", you call for a concrete collar. The detail of the concrete collar shows to match the soffet of the pipe. And the profile shows it to match the flo~v line of the pipe. These two need to be coordinated. Can this change occur in the manhole? 3. Again, where you construct the manhole, it needs to be the appropriate size. 4. It appears you have approximately 1" of clearance from the outside of the proposed 8" sanitary sewer pipe to the outside of the stom~ sewer pipe. That is not an acceptable spacing. 5. Show on the profile the future profile of the pipe extension, as well as the future grade in that area to insure it xvill work out. 6. You show that the 4'X4' grate inlet will be taking a lot of the discharge from that 48" pipe. Again, show those calculations on your inlet calculation sheet. Storm Drain "B" and "C" Plan & Profile - I. The slopes on the laterals on this sheet and the sheet for Storm Drain "D" and "E" are very steep. Is that something that TxDOT will accept in their right-of-way? 3 The inlet shown within the driveway of the site itself is in an unusual position. I believe a lot of water will be bypassing that inlet and getting into the service road. TxDOT needs to either approve that, or yon should relocate the inlet or add potentially another to capture all of your site runoff prior to it getting into the TxDOT right-of-way. Storm Drain "D" and "E" Plan & Profile- 1. Same comment as to the slope of the laterals - a 60% slope is not typically accepted by the City of Coppell. These storm drains are located in the TxDOT right-of-way and will need their approval. Erosion Control Plan - 1. TxDOT needs to approve the erosion control devices for use in their right-of-way. 2. Could the stabilized construction entrance possibly be moved to a location outside of the work area? Erosion Control Details - 1. All details need to be City of Coppell details. Any details that are site or job specific should be included in the plan set. Any details restricted to City of Coppell Standard Details should not appear in the plan set. The contractor is required to have a set of bound City of Coppell details on the site at all times during construction. Utility Site Plan - 1. The proposed fire detector check and vault needs to be moved away from the waterline. If it needs to be located within the paving, the vault needs to be designed and constructed with a structural design to support traffic loading. 2. You need a valve on the 8" Iine between the main and the vault so that if there is an issue with the vault, it can be shut offwithout impacting domestic and irrigation service. See the sketch in the plans for additional information on location of that vault. The 1" domestic line should connect to the main line, not the fire line. Install a 2" blowoff and plug on the west end of the 12" waterline. The fire hydrant in fi'ont of the building should come of f the private side of the vault. 4. 5. 6. Offsite '*Vater Plan - 1. The City of Coppell Water Master Plan calls for a 12" waterline extended from Denton Tap Road to your property and beyond. You are showing an 8" line there. 2. We need a copy of the signed and filed easement document for the proposed 20" utility easement prior to approval of plans. 3. You need to show the profile of the entire line rather than just piecemeal sections of it. 4. A combination air and vacuum release valve is required at any location with a high point. 5. Where the line approaches the site, you are proposing to raise the line to an elevation at or above what is currently the existing grade. Will you be doing your site grading and fill work prior to construction of this line or after? 6. Fire hydrant should be spaced at 300' along this line. 4 Sanitary Sewer Plan & Profile - 1. Again, your clearance where you are crossing the proposed storm sewer line is unacceptable. Provide as much clearance as possible. It appears that with some change in the slope to the sewer line you can provide at least one foot of clearance. Change the slope in that section from 2.16% to something approaching 0.5% to allow for adequate clearance. At that point the manhole upstream could become a drop structure in order to raise the 8" extended to adjacent property. 2. Rather than installing one joint of SDR 26 at that crossing, install one joint of ductile iron pipe, and provide a concrete cradle for the storm drain. Site Paving Details - 1. All construction should be done to City of Coppell standards. Any details specific to the site should be included in the plan set, all others should reference City of Coppell Standard Details. Storm Drainage Details - 1. Once again, paving should be done to City of Coppell standards. Any details specific to this site should be included in plan set, all others should reference City of Coppell Standard Details. 2. The concrete collar shows to match the soffet of the pipe, and the profile sheet shows it to match the flow line. Those should be coordinated. Utility Details - 1. All utility construction should be done to City of Coppell standards. Any details specific to this site should be included in the plan set, all others should reference City of Coppell Standard Details. Easement Documents - 1. The City of Coppell has no comments on the easement documents submitted. 2. In addition to the easements submitted, please provide the documents for the 10' permanent drainage easement on the adjacent property. Please make the necessary changes and submit these marked-up plans and two sets of revised plans to the City for review. If you have any questions, please contact this office at your convenience. Sincerely, Keith R. Marvin, P.E. Civil Engineer Office: 972/304-7044 Fax: 972/304-3570