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Home My WebLink AboutSDP200800051 Calculations 2008-06-26David T. Anhold, CLA ANHOLD ASSOCIATES, PLC Landscape Architecture + Planning 8311 Rockfish Gap Tpke. Greenwood, VA 22943 June 26, 2008 Re: Innovation Drive Dear Mr. Anhold, Thank you for your considering TCS for your engineering services. I have reviewed the stormwater situation on the CAD files you provided and summarize my findings as follows. In general, my task was to examine the channel leading to the DI -7 inlet as well as examine the hydraulic situation at that inlet. I routed the full drainage area through that channel as a 10 year event and find a channel depth of roughly six inches and a 10 year velocity of some 2.79 fps. I then placed that flow into the top of the DI -7 and examined the spread situation. I find that the 10 yr. spread nears seven feet which appears acceptable, given the DI -7 inlet specifications. Finally I examined the hydraulics of the stormsewer considering the line to which this proposed inlet connects. As discussed, I do not have access to the design data of that sewer such as the HGL therefore I can only estimate a tailwater effect. With that in mind, I have considered the receiving pipe as full. Considering the difference in elevations of the rims of the structures in question and the change in HGL across the new line, it is highly unlikely that the 10 yr. event could top the proposed new DI -7. Without a full design/analysis of the existing storm sewer, this can not be fully vetted but I am confident in the new layout. In summary, I find the design as shown on the accompaying review calcs. To be adequate and sufficient. Please let me know if I can help further. Sincerely, Jim Taggart, P.E. For TCS Engineering Co., LLC P.O. Box 306 Nellysford, Virginia 22958 Ph.434/361-1215 Fax 434/361-1216 Email: JTagg2@AOL.com --------- •\ — ' °�°„ \�' � � _ — �. ~�•-°� _ — ,1,111, 1 \ i ,, 11 , It � Ira^` ea*•'r� 40M.� ,- ----y^^'-' .�'+'t say `v II If Starr — „pp�.� „ • iem+e // � � ji'' \ \ 1 111 11 { i 1 A � 1 1 1 1 1 I // , / I \ -- — 1 � • \11111 ♦ — \\`\ it 1111111; IJI I I j 1 ' I I ` ,• \ r � \`�� • ��r• 11111111111 �♦♦ � • tII �',, \ fl \ � �a �_—____" 11111111 1 \ 1 V 1 , 111 / �' 111{1! 1 1 { 111, t 4 ,� � Iijllill 1 r j i ♦� 1 77v i_ • °d'M • I �' ''// VISA- — — ^ 1 1 \ ♦ ° =-.0. yys / . / °ol° • i mow. 1 I 1 O �'� ! 1\ \`\ ( \ /1 /rl V \\♦\ `\` ---dab ��_/--}-( /�/' /.- / .__— i � I' 11 _ .�� l♦ � / 1\ 1 'L1 ♦\ .\!v °�! � � j � / \ \\� — — ' • I A�/v �i'�' '' Ay � � 1 1 1 1 7 1 Z n ♦\ / y \ 1 \\ / / m\ ♦♦I I , / o ems°' r 1, ; Z , i l 5• \ , 1, ♦. -�� '__ - - ' Mme'" ! i;' / 1, AFI �_-___-- � ' ,�/p, ',,' i '' '� ✓J ICI � y%°ri.` /' �� \ I \\ ♦i \ I � / 1 / r 100 'h►J/ ' ♦` ! � '/ ♦\ � it .\` 'q� \ \ { 1 �F. / !Lod' ONO _ Mom aw. IV * —. _ 3.418' 1 Grp • / \ � \ � �Ii' T STATE ROUTE 649 - AIRPORT ROAD M - - '�--- -- ' VARIABLE (MOTH ROW - ' ` , - ��^^^ D.B. 2635 p 454 c' p•� s+�` --_ - \ HIGHWAY PLAT BOOK XIV pp. 186-187 --Ay yA ��7 -` --'' ellffl � ,P�c(-v;1/YG 'J5i7�L— �y ten• J� '��''� �, 2`Nq`h �M1 R`S 4kh_f5 Sle,�, Cf7rygTR1KIgY�T 4l I f3(�Y,: •- ACCP A TO kglNTgryT,TEW.IryE Nr. k5(f V!rL rel It rPAOrry XWAA 07-6 iIWTRO(IG h! 6fP� 8 'I� /1i� �SrIrG IA.v Pw.9Atl Pp h"hrrr.�Yp,Y O�aS wall Ery it i � Ealsrl+,� A: CESS DWV' f fWNf,Y f � r<vs9J so - E ._.. UafPglR�StatKTr� TfR Rgry7 L- TED�",Cgrr 4CCfwl r' eW'S9L P.`-""... MTRgCrgp S4 r5A119 BEcgg f��ap�SA3AE QbuF,y�R �t'T/vu 1.6 ClRg ExISTrrvF ACCP A TO kglNTgryT,TEW.IryE Nr. k5(f V!rL rel It rPAOrry XWAA 07-6 iIWTRO(IG h! 6fP� 8 'I� /1i� �SrIrG IA.v COh TRq�TCW y1i wo� sngeyT ��R ,otrgk�E "iM3 i h"hrrr.�Yp,Y O�aS wall Ery i � Ealsrl+,� A: CESS DWV' f fWNf,Y f � r<vs9J so - E S '-t UafPglR�StatKTr� TfR % .. MTRgCrgp S4 r5A119 BEcgg f��ap�SA3AE QbuF,y�R �t'T/vu ,ir ; i ClRg ExISTrrvF r � ly FI INS "v=JPS p )wy �•SPJ rs A /�`AV``�wPRCP t7gl TI i d✓I.T ✓ Gq-F 8 «t,YI�TFBt R'iOgB[5� Hydrology Report Hydraflow Express by Intelisolve Tuesday, Jun 24 2008 Anhold Innovation Dr. - DI -7 Drainage Area Hydrograph type = Rational Storm frequency (yrs) = 10 Drainage area (ac) = 0.420 Rainfall Inten (in/hr) = 6.825 OF Curve = Greene.IDF Q (cfs) 3.00 2.00 1.00 WIN Peak discharge (cfs) = 2.007 Time interval (min) = 1 Runoff coeff. (C) = 0.7 Tc by FAA (min) = 4 Rec limb factor = 1.60 Hydrograph Volume = 626 (cult); 0.014 (acft) Runoff Hydrograph 10 -yr frequency M Runoff Hyd - Qp = 2.01 (cfs) 5 Q (cfs) 3.00 2.00 1.00 ,T I O 10 Time (min) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Rational Anhold Innovation Dr. - DI -7 Drainage Area Description Flow length (ft) = 200.00 Watercourse slope (%) = 12.00 Runoff coefficient (C) = 0.70 Time of Conc. (min) _ 4 Hydraflow Express by Intelisolve Channel Report HydraFlow Express by Intelisolve Depth (ft) Tuesday, Jun 24 2008 Anhold Innovation Dr.- DI -7 Approach Channel - _ Triangular Highlighted 100 Side Slopes (z:1) = 3.00, 3.00 Depth (ft) = 0.49 Total Depth (ft) = 1.00 Q (cfs) = 2.010 Area (sqft) = 0.72 Invert Elev (ft) = 598.00 Velocity (ft/s) = 2.79 Slope (%) = 3.17 Wetted Perim (ft) = 3.10 N -Value = 0.035 Crit Depth, Yc (ft) = 0.49 Top Width (ft) = 2.94 Calculations EGL (ft) = 0.61 Compute by: Known Q Known Q (cfs) = 2.01 Elev (ft) i I i j -- -- -- -- -- -- i i rT i I I Section 599.50 59900 598-50 050 598.00 000 597.50 -0 50 0 1 2 3 4 5 6 7 8 Reach (ft) Depth (ft) - - T --- I 200 - _ 1 50 100 050 598.00 000 597.50 -0 50 0 1 2 3 4 5 6 7 8 Reach (ft) Inlet Report Hydraflow Express by Intelisolve Anhold Innovation Dr. DI -7 Drop Grate Inlet 2.01 Location = Sag Curb Length (ft) = -0- Throat Height (in) = -0- Grate Area (sgft) = 10.50 Grate Width (ft) = 3.50 Grate Length (ft) = 3.00 Gutter 2.01 Slope, Sw (ft/ft) = 0.083 Slope, Sx (ft/ft) = 0.083 Local Depr (in) = -0- Gutter Width (ft) = 4.00 Gutter Slope (%) = -0- Gutter n -value = -0- All dimensions n feet Tuesday. Jun 24 2008 Calculations Compute by: Known Q Q (cfs) = 2.01 Highlighted Q Total (cfs) = 2.01 Q Capt (cfs) = 2.01 Q Bypass (cfs) = -0- Depth at Inlet (in) = 1.66 Efficiency (%) = 100 Gutter Spread (ft) = 7.33 Gutter Vel (ft/s) = -0- Bypass Spread (ft) = -0- Bypass Depth (in) = -0- i 1 67 400 1 67 Hydraflow Storm Sewers Plan Di -7 0- 1 0 1 6 Outfall Project File: New stm -- -- ---- - ---- _ Number of Imes 2 Date 06-24-2008 Hytlraflow Storm Sewers 2008 v12 01 Hydrafiow Storm Sewers 2008 Hydraulic Grade Line Computations Line Size Q Downstream Len Upstream InvTerH Depth Area Vel Vel EGL Sf Invert HGL�Depth Area Vel Vel elhead elev elev elev head (in) (cfs) I(ft) (s9h) (fUs) (ft) (ft) N (ft) (ft) (ft) (ft) (soft) (ft/s) (ft) 1 15 209 58390 585 15 1 25 1 23 1 70 004 585 20 n/a 38 58650 587 081 0 58" 055 376 022 2 15 2.09 586.50 587,36 086 0 90 l 2 32 008 158744 n/a 55 59000 590.581 0 58" 055 376 0.22 _ -I_ 1 -1 Project File New stm Notes , " Critical depth , /-Line contains hyd lump , c = cir e = ellip b = box Number of lines 2 Page 1 I I --.- 06-24-2008 .-06-24-2008 Hydr a`l— Storm Sewers 2008 v12 01 Sf Check Ave Enrgy JL coeff Minor loss EGL elev Sf loss (ft) f \%) M (ft) (K) (ft) 587 30i n/a n/a n/a 0 70 n/a 590 801 n/a n/a n/a 1 00 n/a I I --.- 06-24-2008 .-06-24-2008 Hydr a`l— Storm Sewers 2008 v12 01 Inlet Resort Page 1 Line No Inlet ID Q = CIA (cfs) Q carry (cfs) t Q Capt (cfs) Q byp (cfs) rate Inlet -- --- L W So W Sw ) (ft) lnl (ft/ft) (ft) (fVft) Gutter —T Sz (ft/ft) t n — — -- Inlet Byp line No rOO Depth Spread Depth (ft) (Ill (n) Spread (ft) Depr (in)1 1 0 00 0 00 0.00 0 00 000 0 00 Sag 0 00 0 000 0 000 0000 000 0.00 000 000 00 Off 2 DI -7 209 000 2 09 000 Grate j 00 000 10.0 3 00 350 i Sag 900 0 083 4 II I I � I I 0 083 0 ODO -0,16 -1 98 017 I 1 41 40 Off � ii i I I Il ' I Project File New stm '— Number of lines 2 _ Run Date. 06-24-2008 NOTES Inlet N -Values = 0.016 . Intensity = 41 75 / (Inlet time + 7 10) ^ 0 71, Return period = 10 Yrs ' Indicates Known Q added All curb inlets are Honz throat Hydrafiow Storm Sewers 2008 v 12 01 Storm Sewer Summary Re Line Line ID Flow Line No. rate size (cfs) (in) 1 A to 1 209 15 2 1 to 2 209 15 I I Project File New stm NOTES Return period = 10 Yrs , i - Inlet control Page 1 Line Line I Invert Invert Line HGL 1 HGL Minor HGL Dns Junction shape length EL Din EL Up slope down up loss Junct line j Type (ftl (ft) (ft) N (ftl (ft) (ft) (ft) No. I Cir 38 583 90 58650 6 806 585 15 58708 n/a 587.36 1 End Manhole C r 55 58650 59000 6.387 58736 59058 n 590 86 1 Grate Number of Imes 2 Run Date 06-24-2008 Hyoraflow Storm Sewers 2008 v12 01 Structure Report Ntrouct Structure ID 1 2 1 DI -7 Project File New.stm Structure Shape Length (ft) Cir 400 i Cir 400 i Page 1 Line Out Junction Rim Type Elev. Shape (ft) Manhole 59350 Grate 59700 Structure Shape Length (ft) Cir 400 i Cir 400 i Page 1 Line Out Line In Width Size—Shape Invert !Size Shape Invert (ft) (in) (ft) (in) (It) i 400 15 Cir 586 50 i 15 Cu 586.50 400 15 Cir 59000 I I i 1 i 1 Number of Structures 2 I Run Date 06-24-2008 i I H y0ragow Storm Sewers. 2008 02 01 �� .�:, x