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<br /> <br /> <br />G <br />Worksheet 3: Time of concentration (Tc) or travel time ('I't) <br />Project: CASTLE ROCK QUARRIES <br />Location: Douglas County, Colorado <br />Condition: Post mining <br />Calculations for: Tc <br />NOTES: <br /> <br />1 <br /> <br /> <br /> <br /> <br />LI <br />Sheet Flow (Applicable to Tc onlvl Segment <br />1. Surtace description (table 3-1) ......................................... <br />2. Manning's roughness ceeH., n (table 3-1) ........................ <br />3. Flow length, L (total L <= 300 R.) ..................................... <br />4. Two-yr 24-hr rainfall, P2 ................................................... <br />5. Land slope, s ................................................................... <br />6. Tt=[0.007 (nL)"(0.6)]/[P2"(0.6) s"(0.4)] Compute Tl........ <br />Shallow concentrated flow <br />7. Surtace description (paved or unpaved) .......................... <br />8 Flow length. L .................................................................. <br />9. Watercourse slope, s ....................................................... <br />10. Average velocity, V (figure 3-1) ........................................ <br />11. Tt = U(3600 V) Compute Tt......... <br />Shallow concentrated Flow (continued) <br />7. Surtace description (paved or unpaved) .......................... <br />8. Flow length, L .................................................................. <br />9. Watercourse slope, s ....................................................... <br />10. Average velocity, V (figure 3-1) ........................................ <br />11. Tt = U(3600 V) Compute Tt......... <br />Segment ID <br />fl <br />ft/fl <br />ft/s <br />hr <br />0.46 <br />T2 T3 <br />unpaved unpaved <br />210 276 <br />0.0333 0.1067 <br />2.94 5.32 <br />0.020 0.014 0.03 <br />Segment ID <br />ft <br />Wft <br />fl/s <br />hr <br /> Channel Flow Segment <br /> 12. <br />13. Cross sectional Row area, a ............................................. <br />Wetted perimeter. Pw ....................................................... <br /> 14. Hytlraulic radius, r =a/pw Compute r........... <br /> 15. Channel slope, s .............................................................. <br /> 16. Manning's roughness coeR., n ......................................... <br />' 17. V = (1.49 r"(2/3) s"(1h))/n Compute V............ <br /> 16. Flow length, L ................... <br /> 19. Tt = U(3600 V) Compute Tt........... <br />I J <br /> <br />1 <br /> <br />0.05 <br />20. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19) ........................ ........................................... hr 0.54 <br />(210-V I-TR-55, Second Ed., June 1986) <br />BASIN L <br />By: TPY Date: 7/24/95 <br />Checked: JGJ Date: 7/24/95 <br /> <br />