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Old Townhomes-CS040305T H E: · C I T Y . O F COPPELL March 5, 2004 Grant M. Woodfin, P.E. C&P Engineering 1801 Gateway Blvd., Suite 101 ~ Development Plan Review C~ Dear ~n: ~ The City of Coppell has reviewed the referenced plans and has the following comments to offer: Water & Sanitary Sewer Plan - 1. The crossing of South Coppell Road for the proposed waterline needs to be done by a method other than open cut, such as bore with steel casing. Bore and steel casing should maintain a minimum separation under the existing 8" sanitary sewer line of 12 to 24 inches. Steel casing should extend a minimum of nine feet beyond that existing 8" sanitary sewer. The existing 8" sanitary sewer may need to be pressure tested and encased in accordance with TCEQ requirements. Please review these requirements and ensure that you meet all minimum standards. 2. Allow at least two feet (2') of clearance between the back of the inlet and the proposed water line. 3. Move the proposed fire hydrant from the present location to between lots 15 and 16 where there is more room between driveways. 4. The waterline in the cul-de-sac area shows an 8" 11.5° bend. I believe that is a 45© bend. Please check that. Sanitary Sewer- 1. Each one of these townhomes needs to have its own tap and lateral to the sanitary sewer line. They will not be allowed to share a service among multiple units. 2. The existing 6" sanitary sewer that you are connecting to may not have the capacity for this additional flow. Also, the condition of the line could be substandard. You should televise the existing 6" sanitary sewer line to show the condition and do an analysis of the capacity with existing properties and with your proposed development. The line may need to be upgraded to an 8" from where your 8" terminates down to the 10" just southeast of that connection. Sanitary Sewer Profiles - 1. There arc several areas where the waterline is crossing the sanitary sewer line - make sure all separation requirements are reviewed and met. If additional encasement or pressure pipe is needed on the 8", please reflect that on these plans. 2. Be sure that the cleanout on Line A is a minimum 6" cleanout. Drainage Area Map - 1. Them appears to be an error in the legend - the drainage area designation shows the drainage area and runoff in CFS - the bottom number is actually area in acres. 2. If fences will be constructed along the back of these townhomes, the drainage will not be able to flow across the back of the homes. This drainage will need to be conveyed to the street, or a privately owned and maintained system will need to be constructed to convey this water. 3. The drainage calculations show 15-minute time of concentration. Should that be I0 minutes? Storm Sewer Plan & Profile - 1. Show the hydraulic grade line for the proposed storm sewer profile. 2. Ensure that there is enough rock rip-rap at the end of this outfall to dissipate any excess velocities. 3. At the junction of the 21" and 18" line where it leaves at a 24" RCP, use a manhole or a junction box rather than a wye connection as shown. 4. The inlets in McNear Drive need to be spaced far enough from the end of the curb return to ensure there is proper room for a gutter transition. Paving Plan & Profile - 1. Again, with regard to the inlets, be sure to leave enough room for the gutter transition. 2. Is handicap-accessible parking a requirement for the on-street parking shown in this area? 3. It appears that some of this proposed parking encroaches into the visibility easement. You may need to rework this proposed parking area. 4. Extend Mobley Way all the way to the south property line. Grading Plan - 1. The legend shows a retaining wall and I don't see one shown on the property, please clarify. 2. The comer of lot No. 9 show a proposed grade of 514.2, and within a few feet there is an existing grade of 513.0. How will this transition work? 3. Verify the grades and drainage patterns on the lots north of this development. Any offsite drainage that presently comes onto this site needs to be accommodated. 4. The proposed grades do not appear to match the drainage arrows shown. Please provide additional detail to show that all stormwater is effectively conveyed to the street, or another acceptable outfall. Erosion Control & SWPPP - 1. Some kind of erosion control device will be needed for the area where you will construct the sanitary sewer and storm sewer lines that go offsite. Show this on the plans. 2. I suggest you move the stabilized construction entrance from where it is shown within the work area to an area such as the existing culvert shown south of the proposed drive. Please make the necessary changes and submit these marked-up plans and two sets of revised plans to the City £or review. If you have any questions, please contact this office at your convenience. Sincerely, Keith R. Marvin, P.E. Civil Engineer Office Phone: (972) 304-7044 Fax: (972) 304-3570