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<br /> <br /> <br />Worksheet 3: Time of concentration (Tc) or travel time (Tt) <br />Project. CASTLE ROCK QUARRIES <br />Location: Douglas County, Colorado <br /> Condition: RECLAIMED <br /> Calculations for: Tc <br /> NOTES: <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br />I J <br />Sheet Flow (Aoolicable to Tc on(vl Segment II <br />1. Surface description (table 3-1) ......................................... <br />2. Manning's roughness coeH., n (table 3-1 ) ........................ <br />3. Flow length, L (total L <= 300 h.) ..................................... <br />4. Two-yr 24-hr rainfall, P2 ................................................... <br />5. Land slope, s ................................................................... ft <br />6. Tt=[0.007 (nL)"(0.8)]/[P2"(0.5) s"(0.4)] Compute Tt........ <br />By: TPY Date; <br />Checked: JGJ Date; <br />0.035 <br />1.9 <br />0.0333 <br />0.13 <br />BASIN E <br />7/20/95 <br />7/20/95 <br />0.13 <br />Shallow concentrated Flow Segment ID <br />7. Surface description (paved or unpaved) .......................... <br />8. Flow length. L .................................................................. ft <br />9. Waterceurse slope. s ....................................................... Nft <br />10. Average velocity, V (figure 3-1) ........................................ ft/s <br />11. Tt = U(3600 V) Compute Tt......... hr <br />Shallow concentrated Flow (continued) <br />7. Surface description (pavetl or unpaved) .......................... <br />B. 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 />Channel Flow <br />12. Cross sectional flow area, a ............................................. <br />73. Wetted perimeter, pw ....................................................... <br />14. Hydraulic radius, r =a/pw Compute r........... <br />75. Channel slope. s .............................................................. <br />16. Manning'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(360C V) Compute Tt........... <br />fl/s <br />ti <br />hr <br />T2 T3 <br />6 6 <br />7.83 7.83 <br />0.77 .77 <br />0.0450 0.0385 <br />0.035 0.035 <br />7.56 6.99 <br />2113 2470 <br />0.08 0.10 <br />20. Watershed or subarea Tc or Tt (add Tt in steps 6, 1 t, and 79) ......... ............... .................... <br />(210-V I-TR-55, Second Ed., June 1986) <br />Segment ID <br />ft <br />ft/ft <br />ft/s <br />hr <br />Segment ID <br />ft^2 <br />fl <br />fl <br />fl/fl <br />0.18 <br />.............. hr 0.31 <br /> <br />