14000000019 Contract

• Contract/PO #: 14000000019
• Contractor Name: Steamboat Springs, City of
• Contract Type: Grant
• Water District: 58
• County: Routt
• Loan Projects - Doc Type: Contract Documents

August 5,2013
Project: Inundation Mapping for the City of Steamboat Springs
Vendor: City of Steamboat Springs; 137 10th Street, PO Box 775088;Steamboat Springs, CO 80477-5088
Phone: [phone]
c/o Mr.Jon Snyder
Consultant: RJH Consultants, Inc.; 9800 Mt Pyramid Court, Suite 330; Englewood,CO 80112
Phone: [phone]
c/o Mr. George Slovensky, P.E.
CWCB funding source: Severance Tax Trust Fund Operational Account
SCOPE OF WORK
RJH Consulting, Inc. (Consultant), at the direction of the City of Steamboat Springs(Vendor), will perform
a dam breach modeling study and flood inundation mapping for two dams within the Vendor's system.
The studies shall be in accordance with the latest Breach Guidelines published by the Colorado Dam
Safety Branch.The level of analysis shall be "Simple,"as defined in Table 1 of the Guidelines for both the
breach modeling and flood inundation mapping. Flood routing models and inundation mapping shall be
based on USGS 10-meter Digital Elevation Model (DEM)or best available topographic mapping.
The two dams to be modeled are at Fish Creek Reservoir and Long Lake. Fish Creek Reservoir is located
on the Middle Fork of Fish Creek and Long Lake is located on the mainstem of Fish Creek.The
downstream limit of the inundation mapping for both Reservoirs will extend along Fish Creek from the
respective dams down to the Yampa River confluence,and further downstream of the Yampa to where
breach flood impacts become negligible. Mapping of both reservoirs will terminate at or before the
Colorado-Utah state line.
The inundation limits shall be prepared in UTM coordinates(NAD 83,Zone 13—meters)which shall be
overlaid on base mapping that includes color aerial imagery(2011 or newer).The inundation map shall
be printed in color on a minimum sheet size of 11"x 17".The inundation extents shall be clearly
illustrated and include peak discharge estimates, peak flood wave arrival times and peak flood wave
depths at critical locations. Roads, highways and critical infrastructure(schools, hospitals,fire stations,
etc.)shall be annotated and any roads expected to be overtopped by the flood wave shall be identified.
The map shall include a legend noting the dam, DAMID, north arrow and a graphic scale.
PROPOSED METHODOLOGY
The Consultant shall perform a clear day dam failure analysis of the dam and route the resulting outflow
hydrographs downstream using HEC-HMS. Breach parameters shall be estimated in accordance with
methodologies recommended by the Office of the State Engineer, Darn Safety Branch. Hydraulic
parameters, including width of flow,depth of flow and velocity at critical locations shall be estimated
using the Corps of Engineer's HEC-RAS computer modeling software.A steady-state water surface
profile resulting from peak flow rates at various locations shall be generated.Topographic information
for the floodplains shall be based on USGS 10-meter DEMs from the National Elevation Dataset(NED)
elevation data.