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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, Colorado <br /> Condition: Post mining <br />' Calculations for: Tc <br /> NOTES: <br /> <br /> Sheet Flow (gpplicable to Tc only Segment ID <br />1 1 Surface description (table 3-7 ) <br />2. Manning's roughness coeff., n (table 3-1 ) ..................... <br />... <br /> 3. Flow length, L (total L <= 300 ft.) .................................. ... ft <br /> 4. Two-yr 24-hr rainfall, P2 ............................................... .... in <br /> S. Land slope, s ................................................................ ... fl/fl <br />' 6. Tt=(0.007 (nL)"(0.6)]/[P2"(0.5) s"(0.4)] Compute Tt..... ... hr <br /> <br /> <br />1 <br /> <br /> <br />By: TPY Date: <br />Checked: JGJ Date: <br />TI <br />BASIN B <br />7/20/95 <br />7/20/95 <br />0.08 <br />Shallow concentrated flow Segment ID <br />7. Surface description (paved or unpaved) .......................... <br />8. Flow length, L .................................................................. ft <br />9. Watercourse slope. s ...................................................... ft/R <br />10. Average velocity, V (figure 3-1) ....................................... ft/s <br />11. Tt = U(3600 V) Compute Tt......... hr <br />Shallow concentrated flow (continued) Segment II <br />7 Suface description (paved or unpaved) .......................... <br />8. Flow length, L .................................................................. <br />9. Watercourse slope, s ....................................................... ft <br />10. Average velocity, V (figure 3-1) ........................................ fl <br />11. Tt = U(3600 V) Compute Tt......... <br />T2 T3 <br />6 6 <br />7,83 7.83 <br />0,77 0.77 <br />0.1023 0.0364 <br />0.035 0.035 <br />11,40 6.80 <br />1545 494 <br />0.04 0.02 <br /> Channel Flow Segment ID <br /> 12. Cross sectional flow area, a ........................................ ..... ft^2 <br /> 13. Wetted Perimeter, Pw .................................................. ..... ft <br /> 14. Hydraulic radius, r =a/pw Compute r...... ...., fl <br /> 75. Channel slope. s .......................................................... .... R/R <br /> 16. Manning's roughness ceeff., n ..................................... .... <br />' 17. V = (1.49 r"(213) s^(1/2))/n Compute V........ .... ft/S <br /> 16. Flow length. L .............................................................. .... fl <br /> 19. Tt = U(3600 V) Compute Tt....... ... hr <br /> <br /> <br />i <br /> <br />20 Watershed or subarea Tc or 7t (add Tt in steps 6, 11, and 19) .................................................................... <br />(210-V 1-TR-55, Second Ed., June 1986) <br />(1.0( <br />hr~ 0.1~ <br />1 <br />