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FS8901-CS 890124 NATHAN D. MAIER CONSULTING ENGINEERS, INC. Janua~ 24,1989 City of Coppell Attention: Engineering Department P.O. Box 478 Coppell, Texas 75019 Re: 4.50-Acre Tract, Coppell, Texas NDM No.: 88-2-017 Gentlemen: Enclosed are two (2) copies of a report prepared for Terra Properties regarding the reclamation of a portion of the referenced tract. The tract is located on the right descending bank of the Elm Fork Trinity River and immediately upstream of the St. Louis and Southwestern Railroad. Because of the existing railroad embankment and the existing filled area downstream of the tract, a portion of the tract is ineffective in transmitting flood flows. This was taken into account in the HEC-2 model used for the Final Reqional Environmental Impact Statement (ELS) for the Trinity River and its major tributaries. In that model, a portion of the area upstream of the embankment was blocked out to account for the non-effective flow area. No additional encroachment is proposed by this request. This report documents and depicts the conditions as modeled for this reach of the Elm Fork. It is proposed to fill the reclaimable portion of the tract to the elevation required by the City of Coppell. However, the current Flood Insurance Study (FIS) shows the tract to be in the floodway. Therefore, upon your review and approval, we would appreciate your forwarding the report to the Federal Emergency Management Agency (FEMA) in Washington, D.C., for their review. Please advise if you have any questions. Sincerely, NATHAN D. MAIER CONSULTING ENGINEERS, INC. Err A. Meyer, P.E. EAM/rdp Enclosures (2) Three NorthPark/8800 N. Central Expwy./Suite 300/Dallas, Texas 75231/(214) 739-4741 FLOODPLAIN RECLAMATION STUDY HRWS TRACT ELM FORK TRINITY RIVER COPPELL, TEXAS FOR TERRA PROPERTIES MARCH, 1988 NDM NATHAN D. MAIER CONSULTING ENGINEERS, INC. FLOODPLAIN RECLAHATION STUDY HRWS TRACT COPPELL, TEXAS I N'£KODUGTI ON This report s--,,arizes the hydraulic evaluation conducted for a 4.50 acre tract of land known as the HRWS tract on the Elm ~ork Trinity River in the City of Coppell, Texas. A specific site development plan for the tract is not currently available. Therefore, the purpose of the report is to show that the subject tract is in the floodplain and not the floodway of the Elm Fork and that a portion of the site could be filled without increasing water surface elevations. SITE.LOCATION The HRWS tract is located west of the Elm Fork, north of the St. Louis and Southwestern Railroad (ST.L~,SWRR) and Belt Line Road; and immediately south of the golf course associated with the Riverchase development in Coppell, Texas. Plate 1 provides a location map for the tract. BACKGROUND The Flood insurance Study (FIS) Floodway Map, revised February 1984, for the City of Coppell, showed the tract to he in the floodway of the Elm Fork. In late 1986, the U.S. Army Corps of Engineers (COE) developed a comprehensive HEC-2 hydraulic model of the Elm Fork which incorporated the modifications to the Elm Fork and its floodplain since the initial FIS. In that model, the filled area downstream of Belt Line Road, which is adjacent to the HRWS tract was incorporated. In addition, the first section (Section 89050) upstream of the ST.L&SWRR was blocked out to reflect a contraction to the opening in the ST.L&SWRR and Belt Line Road. Plate 2 depicts this in plan view, and Plate 4 shows cross section 89050 as used in the model. The property limits of the HRWS tract are also shown on Plates 3 and 4 as they relate to the blocked out areas. In 1987, the COE published the Final Regional Environmental Impact Statement (EIS) for the Trinity River and its major tributaries. The final EIS also incorporated the comprehensive HEC -2 model developed by the COE. In addition, the final EIS utilized discharges from an Existing Conditions and Future Con- ditions 100 -Year and Standard Project Flood � (SPF) based on the watershed hydrology for these conditions. HYDRAULIC EVALUATION For purposes of this evaluation, a portion of the final EIS HEC -2 hydraulic models (GELMF -86 and GEL -2040) for the Elm Fork were used. The portion used commences with Section 87530, downstream of Belt Line Road, and ends with Sec- tion 93670, the Carrollton weir at Sandy Lake Road. The starting water sur- face elevations were taken from the calculated final EIS models. Both the existing and future conditions models were run for the 100 -year and SPF. The HEC -2 input and output data for existing conditions are included in Appendix A, and Appendix B contains the same information for future conditions. Since no additional encroachments are proposed, no increase in water surface elevations occurs as a result of removing the ineffective area from the flood - way. Plate 2 is a copy of the City of Coppell Floodplain Management Map for this area. The ineffective flow area is shown in plan view and the portion of the HRWS tract to be removed from the floodway is highlighted. Of the total 4.50 acres, 3.81 acres are requested to be removed from the floodway. Plates 3 and 4 also show the relationship of the property limits to the ineffective flow area. The tract has been reviewed by the COE in accordance with Section 404 of the Clean Water Act and has determined that a permit from the Department of the Army will not be required to fill the reclaimable portion of the tract. A copy of the letter to that effect is enclosed. DEPARTMENT OF THE ARM FOkl~ WORTH .DISTRICT. CORPS OF ENGINEERS P. O. BOX 17300 FORT WORTH. TEXAS 7elO2-O3OO February 5, 1988 Operations Division Office Operations Branch SUBJECT: Project Number 8800132 RECEIVED NA?HAN O. MAlE CONSULTING EiVGIN:-ERERS Mr. Ervin A. Meyer Nathan D. Maier Consulting Engineers Three NorthPgrk 8800 N. Central Expressway, Suite 300 Dallas, Texas 75231 Dear Mr. Meyer: Thank you for your letter of February 3, 1988 requesting a jurisdictional determination for a fill project located north of Beltline Road and west of the Elm Fora of the Trinity River within Carrollton, Dallas County, Texas. Your project has been assigned Project Number 8800132; all further correspondence concerning the project should include this number. Your project has been reviewed in accordance with Section 404 of the Clean Water Act under which the U.S. Army Corps of Engineers regulates the discharge of dredged and fill materiel into waters of the United States Including adjacent wetlands. Based on your description of the proposed work and all information available to us, we have determined that your project will not involve such discharges and, therefore, will not require Department of the Army authorization. Thane you for your Interest in our nation's water resources. Please continue to check with us prior to Initiating construction in or affecting waters of the United States. If you have addi- tional questions concerning our regulatory program~ please contact Mr. Victor Cole at the address above, telephone (817) 334-4623. Sincerely, Ht~wklns, Jr Office 0pe~ations Branch ~r. David Curtis U. S. Fish and Wi/~-l~fe'$ervice Zoological Services 9A33 Fritz ~ 819 Taylor Fort Worth, T~xas 76102 Texas Parks ar~ W~!~llfe De.ua~.nt 4200 ~mlth Sc.%~ol Boa~ Austin, Texas 78744 \ w r-, f' i '' i ° ;' t rr6ile [: .. , t l I Jl , ,I1 )1 I +I{ y . v i 1 x ,/,'../,::;*. / - . , / too 43 = 1 ND 1",r _ er r 11 !ark 11 • • rra∎ -1 1 f j : _ _ ` „ / ; ` ��� , C- • to 439 I SPi- - .. Ct"ulb a51r _ 11 II --/' ...,.."• j �` %�. � S ot T P, J u > s. 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II o —" I I \ `\ ,F- s t��i I r �� I ' I w71 ` _ � I �� V <J9ll „ \ �i , IIIIIIII. - u ��-^' `� • r :II 1 ) J _ / f ®� \ (�''� " �_m _:� a v, K / 1 ,V ^ \ l . /.%, f ::' dr, ' r a ls i� "� / .• '� � U . - _ r i J ) \ 1��, \" t \ - - ` \.�_ ! x fir M \ \_ ,,, a n• J - LOCATION MAP Purr • r - • / �� \ � � " _ _ _ AZER .Ti: �, \ ( °<' CONSULTING [NOI NATHAN O. M INC. - ` HRWS TRACT 1 ga = = vro �- , ,; _ N 3 1 �� X _, RECLAMATION PLAN • ` ' - / ( ��\ OEq • - -- , J. = _ e ' 1' /�q / • d•rl•• Ir•.• •e•1• d•r• Ile.... lo. •e I s /i N■ LC.. �N I I I (r / 0 • 1 Intl /81.11/411 I' = _000 1.88 I AA - ? - V I * Q i FUTURE Q 100 EXIST. y .00 70.00 80.00 90.00 100.00 119.00 120.00 130.00 140.00 150.00 SECTION 88030 *10 R HRWS TRACT I 1 HRWS TRACT 1 STREAM CROSS - SECTIONS HRWS TRACT COPPELL, TEXAS design drawn scale , date job no. UPSTREAM FACE ST.L. & SW. R.R. "' =100 �i�R 1988 88 -2 -017 D , / PLATE M NATHAN D. AM U e�MwnM ww�w, P.C. 00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 110.00 3 SEC TION 88150 * 10 2 "'"`"""∎/ 10,1.4.4 M.•. Tamar WIN treM� • :aNNw oo'of~ oo'o~ oo'o~ oo'o~ oo'o APPENDIX A EIS EXISTING CONDITIONS 100 -YEAR AND SPF is NDM NATHAN D. MAIER CONSULTING ENGINEERS, INC. March 31, 1988 Mr. Paul Spain Terra Properties 5944 Luther Lane Suite 502 Dallas, Texas 75225 Re: 4.50 Acre Tract, Coppell, Texas NDM No.: 88-02-017 Dear Mr. Spain: We are pleased to submit the attached report which summarizes the hydraulic evaluation conducted for the HRWS tract, a 4.50 acre tract in Coppell. A portion of the tract lles within the shadow of the St. Louis and Southwestern Railroad embankment. It is this portion, 3.81 acres, for which removal from the floodway designation is requested. Upon your review, please advise if you wish the report submitted to the City of Coppell for their review and/or forwarding to the Federal Emergency Management Agency (FEMA). It has been a pleasure to provide these services, and if you have any questions, do not hesitate to call. EAM/rdp Enclosure Very truly yours, NATHAN D. MAIER CONSULTING E. NGINEERS, INC. Three NorthPerk/8800 N. Central Expwy./Sulte 300/Dallas, Texas 75231/(214) 739-4741