HomeMy WebLinkAboutRes-2020-152 Task Order 2BOARD OF COLINTY COMMISSIONERS
COUNTY OF KITTITAS
STATE OF WASHINGTON
RESOLUTIONNO. 2O2O- I5 A,
AUTHORIZING THE CHAIR'S SIGNATURE ON WATERSHED SCIENCES ANI)
ENGINEERING TASK ORDER NO. 2 _ HANSON PITS CIIANNEL MIGRATION AND
AVULSION RISK ASSESSMENT
WHEREAS: Kittitas County Public Works procured on-call professional hydraulic and
hydrology engineering services from Watershed Sciences and Engineering (WSE)
consistent with state law and local purchasing policies in April 2020; and
WHEREAS: WSE has previously conducted technical analyses and developed 2-dimensional
hydraulic model for the Yakima River, and
WHEREAS: The value of Task Order No. 2 exceeds the contract authoriza{ron amount
currently provided the Public Works Director; and
WHEREAS: The Hanson Pits risk assessment is required to inform land management
decisions;
NOW, THEREFORE BE IT RESOLVED that the Board of County Commissioners, in the
best interest of the public, does hereby authorize the Chair's signature on WSE Task Order No. 2
in the amount of $73,355.
DATED this 15th day of September 2020, at Ellensburg, Washington
BOARD OF COUNTY COMMISSIONERS
KITTITAS COLINTY, WASHINGTON
Brett W th,rman
Board- Julie Kjorsvik
Vice-Chairman
I Deputy Clerk of the Board- Mandy Buchholz
'fh41')./TWLE-U Cory Wright, Commissioner
I<ITTITA.S C(OIIIYTY
DEPARTMENT OF PUBLIC WORKS
Formal Task Order Document
WATERSHED Science & Engineering
Task Order Number 2
Maximum Amount Payable $ Z3,3SS Completion Date 2l26l2O2L
The general provisions and clauses of the 2020 -2O22Task Order Master Contract for Hydraulic
and Hydrology Professional Consulting Services shall be in full force and effect for this Task
Order.
Location of Project: Kittitas County
Project Title: Hanson Pits Channel Migration and Avulsion Risk Assessment
Description of Work: See attached Scope of Work
Cost Breakdown: See attached Scope of Work
Completion Date:
Agency Signature Date:ql6wp
Consultant Signature:Date: 91212020
Scope or Services
Hanson Pits Channel Migration and Avulsion Risk Assessment
Kittitas County Flood Control District (County) is advancing a strategy to identify and pursue
funding for projects where the County can decommission obsolete flood control structures and
improve geomorphic processes that create and sustain high quality salmon habitat. The
Hanson Pits levee and downstream private berm have been identified as structures that may no
longer be needed and recent propefty acquisitions landward of these facilities presents an
opportunity to remove or modify the structures and restore floodplain function, The County
owns the Hanson Pits (as series of old gravel barrow pits) and several large agricultural parcels
immediately downstream. The Hanson Pits levee and the private berm are both in poor
condition and likely will fail sometime in the future; however, they currently provide limited
protection for the properties by preventing the river from avulsing or migrating into them. The
County desires to develop and implement a plan that will allow part or all of the Hanson Pits
levee and private berm to be decommissioned, the borrow pits and portions of the floodplain to
be reconnected to the river and restored for habitat, and continued agricultural activities on the
downstream parcels. The County is concerned that removing all or portions of the levee and
berm may allow the river to avulse or migrate into the pits and the downstream properties. This
risk needs to be understood and incorporated into land use planning. Channel migration may be
okay, so long as ecologic function associated with wetland, riparian, and instream habitat is not
degraded and agricultural activities can continue on portions of the downstream properties.
The County has requested Watershed Science & Engineering (Consultant) to conduct an
avulsion / channel migration risk investigation to predict how the river may respond to various
levee/berm decommissioning alternatives for the purpose of helping the County make an
informed decision as to how best to proceed with the decommissioning / restoration project.
The scope of the WSE investigation is described in the tasks below.
TASKS
1. Data Gollection and Review
The consultant shall collect and review existing data needed to complete the avulsion / channel
migration investigation. lnformation will include but not be limited to:
. L|DAR data (2008/2011 and if available 2019)
. Technical documents including recent hydraulic and habitat reports developed as part of
the 2015 Yakima River Corridor Plan
. SRH2D hydraulic model developed for the 2015 Yakima River Corridor Plan
. Current and historical aerial photographs and maps
. Surficial soil data
o Yakima River discharge data
o River sediment grain size, supply, transport, and deposition data
. Design data for levees and revetments
Assumptions:
r The Consultant possesses many of these materials due to their role in the 2015 corridor
study.
o The County will assist the Consultant in obtaining materials as needed.
r The USGS and the DNR collected L|DAR in 2019 for eastern Washington, but it may not
yet be available.
2. Project Goals, Objectives, Constraints and Evaluation Criteria
A meeting will be held with County staff to define project goals, objectives, constraints, and
alternative evaluation criteria.
. Goals are high level statements that describe what the project will accomplish.
. Objectives are more focused statements that describe specific outcomes that the project
should deliver.
. Constrarnfs are limitations that may restrict certain actions.
o Evaluation Criteria are metrics used to evaluate the degree to which alternatives meet
the project objectives.
Deliverables:
. List of draft project goals, objectives, constraints, and evaluation criteria provided to the
County for review.
. List of final project goals, objectives, constraints, and evaluation criteria will be presented
in the project report.
Assumptions:
o This will be a video conference call meeting that will last t hour and will be led by the
Consultant.
3. Bathymetric and Topographic Survey
The consultant will complete a bathymetric survey of the Hanson Pits gravel extraction ponds
and will create a topographic map for the floor of each cell.
Deliverables:
r Bathymetric survey data in an AutoCAD file
. Topography for the floor of each cell.
Assumptions:
. Consultant will provide all equipment required to complete the survey
4. Field Reconnaissance
Consultant and County staff shall conduct a field reconnaissance of the project site. The team
shallexamine:
. Condition and characteristics of the existing Hanson Pits Levee and downstream private
berm.
. Condition and characteristics of the borrow pits,
. Geomorphic characteristics of the active channel in the vicinity of the project site,
including bed and bank morphology and large wood characteristics.
. Geomorphic characteristics of the floodplain, including floodplain surface topography,
forest stand characteristics, and the location of man-made facilities.
During the reconnaissance Consultant and County staff shall discuss the project and possible
alternatives in relation to the stated goals, objectives, and constraints.
Deliverables:
. Observations and photographs to be included in the project report.
Assumptions
r The inspection will last three to four hours.
. A member of the County survey crew will participate for one hour to discuss the
bathymetric survey.
. Physical feature condition assessments will be qualitative. No quantitative testing will
occur (e.9. soil borings, etc.).
5. Hydrology Review
The Consultant shall review and update hydrologic information generated for the 2015 corridor
investigation. They shall update annual instantaneous peak flow flood frequency values as well
as review the characteristics of the irrigation-driven "flip-flop" that occurs in the river each year
between May and September, whereby high and low flows do not correspond to their natural
timing. The key outcomes of this task will be to generate flood hydrographs to use in the
hydraulic model and to associate observed historical geomorphic changes to recorded peak
flood and sustained irrigation summer flip-flop high flows,
Deliverables:
o Updated annual instantaneous peak flood frequency discharges.
. Updated understanding of the timing, magnitude, and duration of the irrigation-driven
"flip-flop".
o ldentification and description in the project report of events that have caused significant
geomorphic.
r change.
Assumptions:
o Deliverables will be included in the project report
6. Hydraulic Modeling
The Consultant shall review and update the existing SRH2D hydraulic model of the project
reach which was created for the 2015 corridor plan. The consultant will:
Update the model topographic mesh using the 2019 L|DAR and surveys from Task 3
and updated publicly-available topography data, if available.
Recalibrate the model if recent flood highwater marks and peak flow data are available.
lf the data are not available, WSE will use engineering judgement to set model
parameters.
Run the model to estimate hydraulic conditions for up to four flow events. Two events
will represent floods that are known to initiate geomorphic change, one will represent a
typical summer prolonged flip-flop flow, and one a habitat flow.
Model geometry will be modified to test up to four different Hanson levee, private berm,
and floodplain reconnection alternatives for the four aforementioned flow events. Model
results will be:
o Compared to the existing condition hydraulic model runs to identify hydraulic
changes attributable to the proposed alternatives.
o Used to evaluate hydraulic patterns and forces in order to predict future
geomorphic change including channel avulsion and migration potential.
Deliverables:
. Model results in the form of GIS figures and tables.
Assumptions:
t lf 2019 L|DAR can be obtained, the Consultant shall use it to update the SRH2D model
geometry in the vicinity of the project.
o Deliverables will be included in the project report.
7. Geomorphic Assessment
The consultant shall conduct a geomorphic assessment to:
. ldentify and characterize the geomorphic processes that currently shape the project
reach and how they are affected by the existing Hanson Pits levee and private berm.
. ldentify past hydrologic events have been responsible for generating significant
geomorphic change to discuss the relationship between flow and the historical
geomorphic evolution of the reach
o Determine whether a river avulsion into the Hanson Pits and/or downstream floodplain is
likely if no actions are taken. lf an avulsion is likely, determine the likely river path,
impact to public and private parcels, and road, rail, flood protection infrastructure.
. Determine whether the channel is likely to migrate into the Hanson Pits or downstream
floodplain if no actions are taken. lf significant channel migration is likely, determine the
likely migration path and rate, impact to the public and private parcels, and road, rail and
flood protection infrastructu re.
a
a
a
a
a Estimate how the river is likely to respond to each for the four project alternatives (see
next task). Predictions will made for two future time periods - 5 years and 25 years in
the future. Because predictions are uncertain, the Consultant will provide an estimate of
the range of possible geomorphic change that may occur as opposed to a single
predicted outcome.
Deliverables:
r Text and figures that present the results of the geomorphic investigation to be included
in the project report.
Assumptions:
. Future geomorphic response predictions are inherently uncertain;therefore, the
Consultant's predictions are approximate and are to serve as general information for the
purpose of comparing the alternatives and defining uncertainty.
. Geomorphic assessment will require up to one day of additional field data collection to
assess geomorphic conditions related to avulsion and migration.
8. Alternative Concepts and Evaluation
The consultant, in consultation with County staff, shall identify up to four project alternatives
The alternatives shall include but not be limited to:
1. Remove the Hanson Pits Levee and private berm completely.
2. Remove portions of the Hanson Pits Levee and private berm. Up to three partial levee /
private berm removal options will be tested.
3. ln combination with 1 and 2 above, the Consultant will include simple floodplain
reconnection actions in the alternatives.
As part of Tasks 6 and 7 above, the Consultant shall run the hydraulic model for each
alternative and use the results help inform the future geomorphic response predictions.
An alternative evaluation matrix will be created to compare the four alternatives using the
evaluation criteria developed in Task 2.
Deliverables:
. Simple concept sketches representing each project alternative.
. Descriptions of the alternatives.
. Descriptions of anticipated geomorphic change and avulsion / channel migration risk.
r Evaluation matrix.
Assumptions:
o This task will allow the County to identify a range of options that will meet the stated
goals and objectives. Phase 2 of this effort will be to engage stakeholders as
appropriate to help selecVrefine a preferred alternative. Phase 2 is not included in this
task assignment.
. Deliverables will be included in the project report.
. Cost Estimates will not be prepared for the alternatives.
. Consultant and Gounty staff will participate in a 2-hour video conference call to identify
the four alternatives to test.
9. Meeting with County Staff to Review Investigation Results
Following Task 8, the Consultant and County staff shall participate in a 2-hour video conference
callto review and discuss the results of the investigation. Meeting outcomes shall include:
. Determining whether alternatives should be refined, or if additional alternatives should
be considered and evaluated.
. Selection of the alternative that appears to meet project goals and objectives.
Deliverables:
. Power Point presentation of the investigation results.
Assumptions:
r Alternative refinements or creating / testing additional alternatives may require a contract
modification.
. Consultant and County staff shall participate in a 2-hour video conference call to review
the results.
10. Technical Report
The results of the investigation shall be summarized in a technical report which will be provided
to the County for review. The technical report will present:
. Project goals, objectives, and constraints,
. Descriptions of existing hydrologic, hydraulic and geomorphic conditions.
. Four alternatives including a concept-level overview sketch of each.
r Anticipated alternative performance including discussion of avulsion and channel
migration potential.
. Evaluation matrix and the rationale for the selection of a preferred alternative.
Deliverables:
. Draft and final report.
Assumptions:
r County staff will review the draft report and provide a single set comments to the
Consultant.
o The Consultant will address the County comments in the final report.
11. Administration
The consultant will perform typical administrative duties including communicating regularly with
the County's project manager, monitoring schedule and budget, and submitting monthly
invoices.
Schedule
TBD
++WA.TEFISH ED
SCIENCE & ENGINEERING
'110 Prefontaine Place South, Suite 508
Seattle, WA 98104
Tel. (206)521-3000
Direct Detail
Cost
Estimate of Professional Services
Prepared for: Kittitas County
Project: Yakima River Hanson Pits
Channel Migration/Avulsion Assessment
Date:
Prepared By:
91212020
Jeff Johnson / Dan Scott
DESCRIPTION
Labor Cosl P€r Firm
LABOR COST
280
3,857
$
$
Total
r'VSE Total
rGS Total
54,978
'18,377
€+WATERSH ED
SCIENCE & ENGINEERING
110 Prefontaine Place South, Suite 508
Seattle, WA 98104
Tel. (206)521.3000
Direct Detail
Cost
Estimate of Professional Services
Prepared for: Kittitas County
Project: Yakima River Hanson Pits
Channel Migration/Avulsion AssessmentOate: September 2,2020
Prepared By: Jeff Johnson / Dan Scott
DESCRIPTION lot.l!
2 6I 6
z. rrojecl 9oars, volec(ves, uonsrarn6 ano Evatualton untefla 2t
J, OaUlyrreurc arro ropograpnE-uruey 0.5 1t 1
1. Tteru neconilatssance I
c. nyororogy Kevrew 4
c. nyorauilu rvroueililg 4 I 80
/. 9EOrIlotpiltu nssesstrlent 60t 24
I
t, Atretilauve uoltceprs anq Evalualon 20
I I,. rvreelilg wtro uour[y DIatr Io xevtew tnves[ganon Kesu6 I 6
I
tu. tectnlrcat Keporl I 16 4 24t 24
I
z 2 1.435
Iotal Hours and Direct Labor Co6t (DL)
Labor Rato ($/hr)
IOTAL LABOR COST $14,A77 $1,435 $j5,264 $22,053 $o $1
$0.560
Total
280
2BO
500 $
$
$
$
54,698
280
54,978Tolal $
Total Labor
Total Dhect Expenses
Pacltlc Geomatlc Seryices, lnc.Estimate of Professional Seryices
CLIENT:
D!t€: U2U20m
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