Debris Basin Removal Feasibility Study
Client: Santa Clara Valley Water District, California
PWR, as a subconsultant
to Kennedy/Jenks Consultants, provided professional services
for the feasibility study to remove an existing debris basin
and headwalls on Calabazas Creek located in California with steep
terrain that results in a high slope gradient.
project involved evaluating the impact of removing the existing
sediment basin on Calabazas Creek from the perspective of sediment
transport and river morphology. Channel stability evaluations
were conducted using an incipient motion and armoring analysis
and an analysis of equilibrium slope was conducted in order to
develop an estimate of sediment continuity for the proposed condition.
HEC-RAS hydraulic modeling was performed for determining the
characteristics of the stable channel geometry. Project work
also included reviews of historic information and aerial photographs,
evaluations of several alternatives from do-nothing, partial
removal to full removal, and sediment transport analyses to evaluate
the short and long-term impacts of each alternative.
and Scour Analysis Table Rock Road Bridge
Client: Department of Roads and Parks; Jackson County,
staff conducted hydraulic/scour analysis for the replacement
of the Oregon Department of Transportation's Table Rock Road
Bridge over the Rogue River in southern Oregon. The work included
a no-rise hydraulic analysis for FEMA, two-dimensional hydraulic
modeling, and scour analyses for the bridge piers and abutments.
A two-dimensional hydraulic model was used to reproduce the significant
features of the observed water surface elevations and the velocity
fields throughout the project site.
detail was paid to the bridge piers and the City of Medford's
drinking water intake, located just downstream from the existing
bridge. The objective was to assure that the replacement bridge
would have no adverse impact on the flow characteristics of the
Medford water intake or at the new bridge's piers and abutments.
A one- dimensional HEC-2 hydraulic model was also developed for
the no-rise analysis. An evaluation was also conducted on the
present river channel alignment to maintain favorable flow conditions
approaching and passing the water intake. This evaluation included
preparation of design alternatives for protecting the intake.
FHWA Hydrologic/Hydraulic Services
Client: Federal Highway Administration
Pacific Water Resources,
Inc. is entering the third year of its second 5-year IDIQ contract
with the Federal Highway Administration (FHWA). These contracts
cover a wide range of services on a variety of assignments including:
field reconnaissance, assessment of flood patterns, fluvial geomorphology,
hydrologic and hydraulic analysis of rivers and river structures,
fish passage studies and remedial designs, bridge scour analysis
and countermeasures designs, evaluation of stream bed material
and stream classifications, and sediment transport studies.
These services have mainly been performed in support of roadway
upgrades along rivers and streams in Alaska, Idaho, Washington,
Oregon, Montana and Wyoming. Projects performed over the last
seven years have included bridges in Glacier National Park (Montana),
Yellowstone National Park (Wyoming), North Cascades National
Park (Washington), Denali National Park (Alaska) and Crater Lake
National Park (Oregon). Assignments normally involve hydrologic
and hydraulic analysis using regional regression equations, HEC-HMS
or HEC-RAS, fish passage mitigation, long-term streambed aggradation
and degradation studies using HEC-18 and development of bridge
scour counter measures. Unusual assignments have included the
effects of glacier melt on river morphology and flooding in various
locations in Oregon, Washington, and Alaska.
The Malheur National Wildlife Refuge is a typical example
of a recent assignment for FHWA. PWR analyzed over 10 bridge
and culvert structures in this refuge renowned for its wetlands
and varied bird species. The project involved assessing the existing
crossings for compliance with fish passage criteria and reconnecting
flood plain areas. Special consideration was given to the basin's
complex hydrology, channel structure, water rights issues and
an adjacent Native American historic site. The
assignment included hydraulic
modeling (HEC-RAS) to evaluate flow velocities at structures
as well as geomorphic studies to assess scour and sediment transport
potential. Based on PWR's recommendations five structures were
replaced using design criteria developed by this task.
Lake Estuary Mitigation
Client: Federal Highway Administration; Tillamook
PWR performed a site reconnaissance
to review the potential impacts of breaching an existing dike
to promote restoration of this historical saltwater marsh system.
The work involved estimating the culvert opening area required
to meet hydraulic, sediment transport and scour concerns. Identified
impacts and issues included saltwater intrusion into the groundwater
table and possible flooding of an existing residence.
The final report identified additional hydraulic, sediment
and scour studies to be performed, a groundwater monitoring plan
to document baseline and changed conditions as well as estimated
costs of professional services required for future phases of