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Alexander Ct-CS070803 Tha ....ett "~r-II"'" II ~ ..., dob.L TBEC H3 N. ....... 8.... P.O. .. 'WI'7 Wylie, TaM ,.. .....: (972) G9-39t3 Po: (m) Gt-3M3 E.....: .....~.......... Mr. Ken 0riftiD, P.E. City of CoppeII, F..neerinB o-.,.-buent 2SS r.kway Blvd. CoppeII, TX 7~19 LETfER OF TRANSMITIAL: 2 sets of CC8II'UCIion drawinp for Alexander Cowl ~ ~ ~ 4~ ~~....'- ~ lA. ~ .......-L t- rr A L. -..... ,.. - .. 03 ~~ C)( ~ ~007 ~ ~~ ~~ ~~~I 4 c..t..r L (:) "3 AuG. '01 Tim Bennett Engineering & Construction, Inc., d.b.a. TBEC 203 N. Jackson Street P.O. Box 2077 Wylie, Texas 75098 Phone: (972) 429-3993 Fax: (972) 429-3963 timbennett3(a;verizon.net August 3, 2007 Ken Griffin, P .E. City of Coppell Coppell, Texas 75019 RE: Alexander Court Dear Mr. Griffin, I have informed Sempco Surveying to change note 4 on page 2 of the plat. Enclosed is a sketch and hydraulic analysis ofthe portion of Olympia Lane just west of the low point. The 100 year Q of 12.5 cfs is not entirely contained in the paving section. The analysis shows that if the water were to rise to 0.1 feet above the T.C. and encroach 5 feet into the parkway, the street would convey 22.9 cfs. With the addition of the inlets on Knights Way, the 15 foot inlet in the sag has been reduced to a 10 foot inlet. The standard 28 foot paving crossection has been revised on both paving sheets. Will the radius on the property line satisfy the requirement for a 10 foot x 10 foot clip for sidewalks on the street intersections? The hydraulic grades shown in the profile of the storm sewer sheet have been revised to match the hydraulic grade line. The concrete cap for the pavement replacement for the open cut in Bethel Road has been added. The mark-up set from 7-23-07 is attached. If you have any questions or other concerns, please call. Sincerely, ~~ Tim Bennett, P.E. crJ J ... L() ~ - " '"' ... ... lr) ,..- . . W ....J ~l <( u (f) m 0::: 0::::::> wU ...- <(u.... 3:0 ICL ...-0 - ...- 3: w >-> ...-0 um <(<( CL <(~ Uu.... . 0 I '0 ...- -- w . wO 0:::: ...-W U1U <( u.... 0::: :::> U1 . . I-- . ~w... ~ (/) L{) N to ~ en .NOw... ~ ~ 00 "- J C() '. __ II II II II N II '"' Q.. lr) <( ~ 0::: U1 > crJ ,........ w... (J1 (j) ~ . 00 '--'" ,........ (J1 (J1 0.... w... w... U "- (j) <( . . >~ N N II II II a >- I-- U <( 0.... <( U I-- W W 0::: I-- (J1 OLYMPIA LANE STREET CAPACITY Street capacity for 28' b-b concrete street on 0.6% slope with water surface at the top of the curb: . n = .014 A = 5.19 SF W p = 28.5 feet R = 0.18 S = .006 Using Scobey chart: V = 2.3 fps Street capacity Q = V A = (2.3) (5.19) = 11.9 cfs Street capacity with the water surface 0.1' above the top of curb; water encroaches 5 feet into the parkway: n = .015 A = 8.49 SF Wp = 38.5 feet R = 0.22 S = .006 Chart gives V = 2.7 fps Street capacity Q = (2.7)(8.49) = 22.9 cfs