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DR9001-CS 870415GINN, INC. CONSULTING ENGINEERS April 15, 1987 Ms. Shohre Daneshmand P.O. Box 478 Coppell, TX 75019 Re: Connell Skaggs Addition Lots 1, 2, & 3 NW Corner Denton Tap/Sandy Lake Dear Ms. Daneshmand: Pursuant to our recent telephone conversations, latest submittals from the engineers, and your stated concerns regarding the above referenced subject, we offer the following comments for you consideration. 1. Since we were not involved in discussions, decisions, agreements, etc., between the "preliminary" submittal and the present "final" submittals, we are at a disadvantaga. Any written documentation between the city and owners, the City Engineer (at that time, Mr. Ed Powell), and the engineers for the project (Powell and Powell), would provide helpful insight as to decisions made and/or accepted. 2. Because the property upstream of the Connell tract is presently being submitted for approval and parts of Lot 3 are being developed with drives and parkihg, we would sugge~ advisimg the developers to provide the design and construction o2 the proper drainage facilities to. adequately convey"-~aIi ~nof~ from the site and that which the present ditch handles plus upstream develOpment. 3. Since Lot 3 is included in this "final" plat submittal, t~ agreement between Connell and City stipulates that "... a letter of credit be provided or monies escrowed for construction pf t~ box culvert from Sandy Lake Road to Willow Lane, at some la time, such time to be determined at the sole discretion of the. City Council, based upon recommendation of the City Enqineer." It is our raqommendation that the box culvert be constructed at · his point in time. - 4. If, due to previous agreements or commitments, ~onnell does no__t have to construct the box culvert at this time, ~s~t that the exlsElnq ditch on the west end of the Conne~l tract~qDe ~Droved. a~ rc~'l~ed, to adequately handle the anticipat~ ~ Allowing the open channel is in direct cohflict with the subdivision ordinance, which states no open channels allowed; and, will have to have a variance approved. 17103I'rcsto,lRoad ~' Suite 100 · lB liS · Dallas, Texas75245; · Phone 214/248-4900 5. The plat should designate an adequate drainage easement for construction o~ the DOX culvert and Should be located entirely on the Connell tract, un the zu' ~ralnage and utility easement on the Shadydale Acres tract, it would be difficult to construct a box culvert due to encumbrances, 48" oaks throughout, and the mere fact that just because a plat indicates a drainage easement does not mean that adjoining lands have no obligation to provide drainage upon their own site, where a natural existing drainage flow occurs. 6. The screening wall should be constructed at this point in time and not at a later date. This again is part of Coppell ordinances and any deviation will have to have a variance requested. The entire tract should be considered as one, regarding screening. Whether the buildings are constructed on Lots 1, 2, or 3 should not have any affect on the visual screening of the residents of Shadydale Acres tract. 7. Regarding "sheet" flow of drainage across the site from east to west, with no provisions for detention or collection, it is our opinion that during a 100-year storm event (Q = 72 c.f.s., d = .68', V = 4.4 f.p.s.) or even the 10-year storm event (Q = 49 c.f.s., d = .59', V = 4 f.p.s.), the runoff could conceivably present a problem to motorists and pedestrians using the parking area on this site regarding safety. 8. We acknowledge that the design storm event should pass quickly; and, allowing the runoff to be conveyed in a wide path vs. concentrated discharge points would cause less erosion. But, if the box culvert were constructed and a storm sewer collection system provided, it would alleviate some of the potential fears and problems that may occur. 9. If the engineers are determined to sheet flow across the site, then the City should stand firm in its desire to have the box culverts constructed at this time. Also, the maximum allowable "sheet flow" we should accept should be 20 c.f.s. When the flow exceeds this 20 c.f.s., it will have to be collected and transported by other means, i.e. underground piping. If you have any additional concerns, please contact us. Sincerely, Gabe Favre /ss cc: Alan Ratliff Wayne Ginn II I¢ The City With A Beautiful Future P. O. Box 478 Coppell, Texas 75019 214 - 462 - 0022 December 19, 2986 Ms. Cynthia J. Crass Real Estate Counsel American Stores Properties, Inc. 5201 ~nelia Earhart Salt Lake City, Utah 84116 RE: Drainage Condition to Preliminary Plat, Connell Skaggs Addition, Coppell , Texas Dear Ms. Crass: Connell Development Company has agreed to construct a box culvert drainage system in conformance with the City of Coppell ' s requirements relative to the platting of the referenced property. Futhermore, an agreement has been reached between Connell and the City to escrow an appropriate amount of money to provide for funding of the entire system to a designated point downstream. It is the opinion of the City of Coppell that this agreement fully satisfies the condition to the plat; therefore, American Stores Properties, Inc. may apply for final plat and a Building Permit without the drainage condition attaching to your plat on parcel 1. Using generally accepted engineering procedures, you will still be required to provide for adequate site drainage using the existing channel located at the west side of the Conn el 1/Ska ggs a ddi t i on. Very truly yours, Frank Trando Iterim City Manager