FLOOD00281

• County: Larimer
• Community: Greeley
• Title: Design Criteria and Construction Specifications volume 2 of 5 Storm Drainage Criteria
• Date: 10/1/1997
• Prepared For: Greeley
• Prepared By: Department of Public Works
• Floodplain - Doc Type: Educational/Technical/Reference Information

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<p = 0.00492

This value remains constant for this design since
the n-value does not change.

STEP 2:

Velocity Head (Column 10):

Hv = V2 =
2g

(6.1)2
(2) (32.2)

Hv = 0.58

STEP 3:

Energy Grade Point, E.G. (Column 11):

E.G. = W.S. + Hv = 100 + 0.58

E.G. = 100.58

For the initial calculation, the Energy Crade Line is
computed as described above. For subsequent
calculations, the equation is reversed, and the water
surface is calculated as follows (see step 12):

W.S = E.G. - Hv

This equation is used since the losses computed in Step
8 are energy losses which are added to the downstream
energy grade elevation as the new starting point from
which the velocity head is subtracted as shown above.

STEP 4:

Sf =

<pH =
R413

(.004921 !0.58)
(1. 375) /

Sf = .0019

Note: R = the hydraulic radius of the pipe

STEP 5: Avg Sf (Column 13):

Average skin friction: This is the average value
between Sf of the station being calculated and the
previous station. For the first station, Avg Sf =
Sf' Beginning with Column 13, the entrees are
placed in the next row since they represent the
calculated losses between two stations.

STEP 6:

Enter sewer length, L, in Column 14.

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