PROJ00297

• Contract/PO #: C153507
• Contractor Name: Greeley, City of
• Contract Type: Loan
• Water District: 3
• County: Larimer
• Bill Number: SB 87-15
• Loan Projects - Doc Type: Feasibility Study

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Gl 11. Equations(s) and spilhiay discharge table.

Gl 12. Reservoir elevation storage table to the crest of the da~.

B. The hydrologic da~ break analysis for spill~/ay design less than PIIF
should include the following:

n/a 1. Fl ood pl ai n map of inundated critical area showi ng pre and
post failure high water lines.

n/a 2. Cross sections to scale with elevation and channel I~idths.
Sholiing pre and post failure water lines including
discharges and average velocities.

a. Just below da~.
b. Intermediate channel sections.
c. Critical sections within the inudated critical area.

n/a 3. Hydraulic parameters assumed.

n/a 4. Sensitivity analysis of assumptions; i.e., time to complete
failure, depth of overtopping, channel roughness (Mannings
IInll).

n/a 5. Estimated probabil i ty of the fail ure of the dar.1 by
overtopping based on reoccurrence interval of flood.

n/a 6. Discussion of why the damage resulting from an overtopping
dam failure is insignificant.

n/a 7. COr.1puter printout of the dar.1 break flood.

n/a 8. The dar.1 break flood study shoul d cOr.1ply with the concepts
outlined in Design Revieli tler.1orandur.1 No.4.

III. HAZARD RATING DM1 BREAK CLASS I (HIGH HAZARD)

A. As a separate report or a report section of the hydrology report, the
engineer shall evaluate the hazard of the daD.

Criteria shall be as follol/s:

n/a 1. The nonhydrologic failure shall consider the reservoir full
at the norr.1al high water line.

n/a 2. Several reasonable failure rates shall be evaluated to
determine the sensitivity of the assur.1ed parar.1eter.

n/a 3. Analysis of flood inundation shall continue dO\/nstrear.1
until the flood stage is equal to or less than the lOO-year
flood plain.

21 34H/3