PROJ00484

• Contract/PO #: C153788
• Contractor Name: Greeley and Loveland Irrigation Company
• Contract Type: Loan
• Water District: 3
• County: Weld
• Bill Number: FSL
• Loan Projects - Doc Type: Feasibility Study

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Study Plan - Greeley and Loveland Irrigation System Rehabilitation Feasibility Study

Page 3

Task 2 - Hydrologic Analysis
Objective:
State approval for repair and rehabilitaion will require that the Company's dams meet current state dam safety
standards, The State Engineer's Office (SEa) presently uses 1988 HMR-55A for their hydrologic analyses, The
State is presently sponsoring a Colorado regional probable maximum precipitation (pMP) study, The study will
impact reservoirs above elevation 7500 feet so it will not have any future impacts on this study, The PMF's will
be used in the following tasks to evaluate the existing dams and appurtenant structures and develop alternatives,

Methodology:
1. The local and general PMP storms will be computed based on the HMR-55A.
2, 1 DO-year flood hydrographs will be developed based on the NOAA Atlas II,
3, Existing reservoir elevation-area-capacity curves will be verified with existing topographic maps,
4, Spillway and outlet rating curves will be verified
5, Preliminary reservoir flood routing will be performed to check the spillway capacity adequacy,

Products:
1. A memorandum will be prepared describing the analytical methods and results of the hydrologic
evaluation,
2, Flood hydrographs for the local and general PMP storm events and 1 DO-year flood hydrographs,

Task 3 - Existing Facilities Evaluation
Objective:
The Company's system has never been hydraulically modeled to identify possible operation issues, Reservoir
and canal operations need to be analyzed to identify restricted flow reaches due to structural and nonstructural
issues,

Methodology:
1. A decision support system (DSS) hydraulic simulation model of the Company's system will be
developed using CanalMan, CanalMan was ordinally developed by the USBR and has been modified
for the windows environment by Utah State University,
2, Calibrate the model with existing weir rating curves and historical flow depths,
3, Perform hydraulic simulations using varying canal discharges and system operation rules,
4, IdentifY problem reaches and structures within the system to be addressed in Task 4 Alternative
Development.

Products:
1, A memorandlHll will be prepared describing the analytical methods and results of the existing facilities
evaluation,
2, A working DSS hydraulic model which will be given to the Company for future use,
3, ECI will give a one-day modeling training program for selected Company personal on the use of the DS S
hydraulic model.
4, A system matrix which will identifY problem reaches, The system matrix will be used in Task 4
Alternative Development.

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