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<br />i <br />Worksheet 3: Time of concentration (Tc) or travel time (Tt) <br /> Project: CASTLE ROCK QUARRIES <br /> Location: Douglas County, Colorado <br /> Condition: Post mining <br />' Calculations tor: Tc <br /> NOTES: <br /> <br /> Sheel Flow (Applicable to Tc only) Segment ID <br /> 1. Surface description (table 3-1) ......................................... <br /> 2. Manning's roughness coeff., n (tab~e 3-1) ........................ <br /> 3. Flow length, L (total L <= 300 R.) ..................................... I <br /> 4. Two-yr 24-hr rainfall. P2 ................................................... i. <br />t 5. Land slope, s ................................................................... tU1 <br /> 6. Tt=[0.007 (nL)"(0.8)y[P2"(0.5) s"(0 4)] Compute Tl......,. h <br />Shallow concentrated flow Segment ID <br />7. Surface description (paved or unpaved) .......................... <br />B. Flow length, L .................................................................. fl <br />9. Watercourse slope. s ....................................................... ft/ft <br />10. Average velocity, V (figure 3-1) ........................................ tl/s <br />11. Tt = U(3600 V) Compute Tt......... hr <br />TI <br />J.13 <br />300 <br />1.9 <br />By: TPV Date: <br />Checked: JGJ Date: <br />BASIN N <br />7/24/95 <br />7/24/95 <br />0.37 <br />T2 <br />unpaved <br />246 <br />0.0488 <br />3.56 <br />0.019 0.02 <br />Shallow concentrated flow (continued) Segment ID <br />7. Surface description (paved or unpaved) .......................... <br />8. Flow length. L .................................................................. ft <br />9. Watercourse slope, s ....................................................... fl/ft <br />10. Average velociy, V (fgure 3-1) ........................................ fl/s <br />11. Tt = U(3600 V) Compute Tt......... hr <br /> <br /> <br /> <br /> <br /> <br /> <br />L <br />Channel Clow Segment <br />t2. Cross sectional Bow area, a ............................................. '~ <br />13. Wetted pedmeter, Pw ....................................................... <br />14. Hydraulic radius, r =a/pw Compute r........... <br />15. Channel slope. s .............................................................. <br />16. Manning's roughness weff., n ......................................... <br />17. V = (1.49 r"(2l3) s"(1/2))/n Compute V............ <br />18. Flow length, L .................................................................. <br />19. Tt = U(3600 V) Compute Tt........... <br />20. Watershed or subarea Tc or Tt iadd Tt in steps 6, 11, and 19) ............................ <br />(210-V1-TR-55, Second Ed., June 1986) <br />0.06 <br />.................................. Itr 0.45 <br />1 <br />