RECOVERY--C--PROJECT NUMBER , OWS Upgrade Hydraulic Modeling of Warm Springs Dam for With and Without Failure of the Dam and Inundation Mapping

The contract award amount is $2,999.79

RECOVERY - PER FAR 5.7 THIS NOTICE IS PROVIDED FOR INFORMATION PURPOSES ONLY; THEREFORE FAR 5.203 DOES NOT APPLY. THIS OPPORTUNITY WAS AVAILABLE ONLY TO CONTRACTOR(S) UNDER THE CURRENT CONTRACT NUMBER(S): MCMILLEN, LLC W91238-10-D-0001-CPO2

This contract action was accomplished using other than competitive procedures because this is a task/delivery order where an exception to fair opportunity requirements was approved as this is a follow-on order to a competitive initial order (FAR 8.405-6(b)(2) or 16.505(b)(2)(iii).

BACKGROUND: Warm Springs Dam, Lake Sonoma is located on Dry Creek, in Sonoma County, California 14 miles above the confluence with the Russian River and the City of Heasldsburg. The San Francisco District (District) owns and operates two reservoirs on tributaries to the Russian River, Warm Springs Dam, Lake Sonoma in Sonoma County and Coyote Valley Dam, Lake Mendocino, on the EF Russian River in Mendocino County. Both dam are multi-purpose projects, consisting of flood control, water conservation and recreation facilities operated by the US Army Corps of Engineers, San Francisco District to reduce flood damages.
Warm Spring Dam was completed in the early 1980s and consists of a rolled earth embankment, with a dam crest of 319 ft above the streambed. At gross pool, Lake Sonoma captures 381,000 acre-feet of runoff from the upper Dry Creek watershed, 130 square miles, above the Dam. Outlet flows are regulated via the projects two service gates and multi-level low flow outlet and an unregulated ogee spillway for emergency releases. The design flood peak inflow and outflow are 77,000 and 37,700 cubic feet per second, respectively, with 6 feet of freeboard.
This study shall examine the adequacy of the Warm Spring Dam Spillway and its effects downstream of the dam, along Dry Creek and the Russian River.

3) OBLIGATION OF CONTRACTOR: The Contractor shall gather information, collect data, and perform analyses as necessary to successfully complete the tasks given in section 5 of this scope of work. All technical work performed as part of this scope of work shall be conducted by personnel trained in hydrology and hydraulics with a minimum of 3 years of experience. The work shall be supervised by a person trained in hydrology and hydraulics with a minimum of 10 years of experience who is also registered in the state of California as a civil engineer.


4) OBLIGATION OF THE GOVERNMENT: Government personnel will be available for advice, guidance, and comments on all work under this contract. Any comment, advice and/or guidance given by the Government personnel will be to assist the Contractor in performing the work and will not change the scope of work or release the Contractor from performing all work required herein unless written notification of such, signed by the Contracting Officer (CO) is received by the Contractor. Should the Contractor require assistance from the Government in regards to this scope, they shall contact one of the Government's points of contacts given in section 1 of this scope of work. The Government's point of contact will then either assist the Contractor directly, or provide an appropriate point of contact to answer the Contractor's questions.

5) DESCRIPTION OF WORK: The purpose of the study is to evaluate the adequacy of the Warm Spring Dam Spillway and to determine the most likely downstream inundation area and flood depths in case of failure of the dam. The analysis shall determine the downstream inundation caused by both with and without failure analysis of the dam for the Probably Maximum Flood (PMF), as well as the 50-, 100-, 200-, and 500-year frequency based storms and a sunny day failure scenario. The study also includes mapping of the various failure analyses.

The flood wave shall be routed from Warm Springs Dam, along Dry Creek to the Russian River to the Pacific Ocean. The District just completed a similar study for Coyote Valley Dam in July 2009. Coyote Valley Dam is also located in the Russian River watershed, upstream of Warm Springs Dam and Dry Creek. The Coyote Valley Dam study routed the flood wave from Coyote Valley Dam thru the Russian River to the Pacific Ocean. The hydraulic model used for the Russian River portion of the study has already been developed as part of the Coyote Valley Dam study and shall be used for this study for the Russian River reach between Dry Creek and the Pacific Ocean.

The same methodology for the Coyote Valley Dam study shall be used in this study. This report shall be made available to the contractor for review prior to the Fee Proposal due date. The study will include the use of existing GIS data, terrain model, flow data, high water marks, hydraulic and hydrologic models developed for the entirety of the Russian River watershed for the Coyote Valley Dam study.

Additional data shall be provided to the contractor specific to Warm Springs Dam and Dry Creek. Additional cross section data is available for Dry Creek from the District office and shall be provided to the contractor. However, it will be necessary to develop additional channel data along Dry Creek based on FEMA profiles, site visit and older HEC-2/HEC-RAS geometries. The hydraulic models will be calibrated and validated to available historic data. Calibrated models will be used to model all of the events. Data specific to calibration of the models, such as high water marks, is limited and additional research will be necessary to determine the availability and quality of such data.

The purpose of the study is to evaluate the adequacy of the

Warm Spring Dam Spillway. The analysis shall determine the downstream inundation caused

by both with and without failure analysis of the dam for the Probably Maximum Flood (PMF),

as well as the 50-, 100-, 200-, and 500-year frequency based storms and a sunny day failure

scenario.

The District just completed a similar study for Coyote Valley Dam in July 2009; the same

mythology shall be used in this study. This report shall be made available to the contractor prior

to the Fee Proposal due date. The Coyote Valley Dam study routed the flood hydrographs from

Coyote Valley Dam, thru the Russian River watershed (1400 square miles) to it's terminus at

the Pacific Ocean. The Russian River hydrology model developed for the Coyote Valley Dam

study shall be used for this study, with modifications to the Dry Creek watershed (270 square

miles).

The Russian River hydrology model, as well as the flow data, precipitation data, GIS data, land

use data, hydrologic models, and other data generated as part of the Coyote Valley Dam study

shall be provided to the contractor for use in this study. Again, only the Dry Creek watershed

shall require a detailed analysis, the existing Russian River hydrology model shall be used for

the Russian River portion of the modeling effort.

The hydrology model (HEC-HMS) will be calibrated and validated to the same historic data as

the Coyote Valley Dam Study. Calibrated models will be used to model all of the events. The

models will be run for with and without failure analysis of the dam for the 50-yr, 100-yr, 200-yr,

500-yr, and PMF events and a Sunny day failure scenario.