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<br /> <br />1 <br /> <br />Worksheet 3: Time of conceotratioo (Tc) or travel time (Tt) <br />Project: CASTLE ROCK QUARRIES <br />Location: Douglas County, Colorado <br />CondBion: Post mining <br />Calculations for: Tc <br />BASIN D <br />By: TPY Date: 7/20/95 <br />Checked: JGJ Date: 7/20/95 <br /> NOTES: <br />i <br /> She et Flow (ppplicahle to Tc only) <br /> 1 Surtace tlescriplion (table 3-t ) <br />1 2. Manning's roughness weff., n (table 3-1 ) ........................ <br /> 3. Flow length, L (total L <= 300 ft.) ..................................... <br />' 4. <br />5. Two-yr 24-hr rainfall. P2 ................................................... <br />Land slope, s ................................................................... <br /> 6. Tt=[0.007 (nL)"(0.8)]/[P2"(0.5) s^(0 4)] Compute Tl........ <br /> Sha llow concentrated flow <br /> 7. Surface description (paved or unpavetl) .......................... <br /> 8. Flow length. L .................................................................. <br /> 9. Watercourse slope, s ....................................................... <br /> 10. Average velocity, V (fgure 3-1) ........................................ <br /> 11. <br />h Tt = U(3600 V) Compute Tt......... <br />ll <br />i <br />d fl <br />d) <br /> S a <br />ow concentrate <br />ow (cont <br />nue <br /> 7. Surtace description (paved or unpaved) .......................... <br /> 8. Flow length. L .................................................................. <br /> 9. Watercourse slope, s ....................................................... <br /> 70. Average velocity, V (fgure 3-1) ........................................ <br /> 11. Tt = V{3600 V) Compute Tt......... <br /> <br />i <br /> <br /> <br />1 <br /> <br /> <br />Segment ID TI <br /> woods <br /> 0.035 <br />ft 300 <br />in 1.9 <br />Nft 0.1233 <br />hr 0.08 <br />Segment ID <br />ft <br />Wft <br />fl/s <br />hr <br />0.08 <br />T2 <br />unpaved <br />1,600 <br />0.0857 <br />4.72 <br />0.094 0.09 <br />Segment ID <br />ft <br />ft/ft <br />ft/s <br />hr <br />Channel flow Segmen <br />12. Cross sectional Bow area, a ............................................. <br />73. Wettetl perimeter, Pw ....................................................... <br />14. Hydraulic radius, r =a/pw Compute r........... <br />15. Channel slope, s .............................................................. <br />16. Manning's roughness coeff., n ......................................... <br />17. V = (1.49 M(2/3) s"(t/2))/n Compute V............ <br />78. Flow length, L .................................................................. <br />79. Tt = U(3600 V) Compute Tt........... <br />20. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 79) ....................................... <br />(210-V 1=fR-55, Second Ed., June 1986) <br />...................... hr 0.1 <br /> <br />