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<br /> <br />Worksheet 3: Time of concentration (Tc) or travel time (Tt) <br /> Project: CASTLE ROCK QUARRIES <br /> Location: Douglas County, Coloratlo <br /> Condition: Post mining <br />1 Calculations for: Tc <br /> NOTES: <br /> <br /> Sheet Flow (Applicable to Tc onlvJ Segment ID <br /> 1. Surtace description (table 3-1 ) ..................................... <br />2. Mapping's roughness coefl., n (tab~e 3-1) ..................... ... <br />... <br /> 3. Flow length, L (total L <= 300 fl.) .................................. ... R <br /> 4. Two-yr 24-hr rainfall, P2 ............................................... .... in <br /> S. Land slope, s ................................................................ ... Wfl <br />' 6. Tt=(0.007 (nL)"(0.8)]/[P2"(0.6) s"(0.4)] Compute Tt..... ... hr <br />' Sh allow concentrated flow Segment ID <br /> 7. Surtace description (paved or unpaved) ....................... ... <br /> 8. Flow length, L .............................................................. .... ft <br /> 9. Waterwurse slope, s ................................................... .... fl/ft <br /> 10. Average velocity, V (figure 3-1) .................................... .... ft/s <br /> 11. Tt = U(3600 V) Compute Tl..... .... hr <br />By: TPY Dale: <br />Checked: JGJ Date: <br />rl <br />0.035 <br />300 <br />1.9 <br />0.2 <br />BASIN 1 <br />7/2 i/95 <br />7/21 /95 <br />0.06 <br />T2 <br />unpaved <br />608 <br />0.1234 <br />5.67 <br />0.030 0.03 <br /> <br />1 Sha llow concentrated flowlcontinuedl Segment ID <br /> 7. Surtace description (paved or unpaved) ....................... ... <br /> 6. Flow length. L .............................................................. .... ft <br /> 9. Watercourse slope, s ................................................... .... ft/ft <br /> 10. Average velocity, V (figure 3-1) .................................... .... ft/s <br /> 11. Tt = U(3600 V) Compute Tt..... .... hr <br /> <br /> Channel Flow Segmen <br /> 12. <br />13. Cross sectional flow area, a ............................................. <br />Wetted perimeter. Pw ....................................................... <br /> 14. Hytlraulic radius, r =a/pw Compute r........... <br /> 15. Channel slope. s .............................................................. <br /> 16. Mapping's roughness coeH., n ......................................... <br />' 17. V = (1.49 r"(2/3) s"(1/2))/n Compute V. <br /> 18. Flow length, L ................... <br /> 19. Tt = U(3600 V) Compute Tt........... <br />1 <br /> <br /> <br /> <br />20 Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19) ....................................................................... <br />(210-V 1-TR-55, Second Ed., June 1986) <br />hr 0.09 <br /> <br />