Loading...
HomeMy WebLinkAboutRes-2022-075BOARD OF COUNTY COMMISSIONERS COUNTY OF KITTITAS STATE OF WASHINGTON RESOLUTTON No. 2022 - -az' AUTHORIZING THE CHAIR'S SIGNATURE ON WATERSHED SCIENCES AND ENGINEERING TASK ORDER NO. 4 _ EASTON REACH YAKIMA RIVER HAZARD ANALYSIS AND MAPPING INVESTIGATION WHEREAS: Kittitas County Public Works (PW) recently received a Flood Control Account Assistance grant from the Washington State Department of Ecology to flood study the Easton reach of the Yakima River; and WHEREAS: Kittitas County Public Works procured on-call professional hydraulic and hydrologic engineering services from Watershed Sciences and Engineering (WSE) consistent with state law and local purchasing policies in April 2020; and WHEREAS: WSE previously conducted technical analysis, developed a 2-dimensional hydraulic model, and conducted a channel migration and avulsion risk assessment for the Kittitas Reach Yakima River: and WHEREAS: The Easton Reach River Hazard Analysis is required to complete the scope of work for Washington State Department of Ecology Flood ControlAccount Assistance Program Funding, accepted by Kittitas County by Resolution202l-179 and WHEREAS: This project is identified on the Flood Control Zone District Annual and six-year work plans; and WHEREAS: The value of Task Order No.4 exceeds the contract authorization amount currently provided to the Public Works Director. 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. 4 in the amount of $245,261. DATED this 15th day of March,2022,at Ellensburg, Washington. BOARD OF COUNTY COMMISSIONERS .,r1\tllll I I llllll7r,, ,..}u :9.YY!|li;;ro ---'t"{ .l{'-, *- C) .' : : ,-rx--l A fr : =?= i. ll [Atfdstr--, , = -= =- t.\. r*oS %"5#*ust* B oard- Jur ie Kj orsv ik """rgrgb\iuty Clerk of the Board- Mandy Buchholz Wright, V , WASHINGTON Brett W Commissioner KITTITAS COUNTY DEPARTMENT OF PUBLIC WORKS Formal Task Order Document WATERSHED Science & Engineering Task Order Number 4 Maximum Amount Payable $245,26L Completion Date 12t3U2023 The general provisions and clauses the 2020 -2022 Task Order Master Contract for Hydraulic and Hydrology Professional Consulting Seruices shall be in full force and effect for this Task Order. Location of Project: Kittitas Corurty, Easton Reach Yakima River Project Title: Easton Reach Yakinra River Hazard Analysis arrd Mapping Investigation Description of Work: See attached Scope of Wolk Cost Breakdown: See attached Scope of Work Project Schedule: See attached of Work Agency Signature: Consultant Signature:( Date: \MWMJ67CIAA Date: H l?r.H $, ?,oal Easton Reach Yakima River Hazard Analysis and Mapping lnvestigation Consultant Scope of Work Kittitas County (County) is concerned that there are undefined flood and channel stability hazards in the 1 1-mile Yakima River Easton Reach (RM 1 91 to 2Q2) which extends downstream from Easton Dam. The reach contains four communities with large-scale developments with urban densities that are routinely flooded by the Yakima River and are repetitive loss areas. Despite their reputation as locations with flooding issues, flood hazards have not been adequately assessed and specific strategies to address flood hazards are lacking. These risks need to be defined to support County land use planning. The County has requested that Watershed Science & Engineering (Consultant) develop a scope of work to conduct a flood, avulsion, and channel migration hazard assessment to identify areas that are most at risk along this reach of the Yakima River. The study will include new HEC-RAS two dimensional (2D) hydraulic modeling of the reach developed in accordance with FEMA guidelines for Flood Risk Analysis and Mapping (FEMA 2016). Results will be used to support flood and geomorphic hazard assessment and to develop new inundation mapping to update FEMA flood insurance rate maps. The scope is described in the tasks below TASKS 1 DATA COLLECTION AND FIELD RECONNAISSANCE 1.1 Background Data Collection and Review The consultant shall collect and review existing data needed to complete the flood, avulsion, and channel migration investigation. lnformation will include but not be limited to: o L|DAR data (2005 ,2011, 2014, and more recent if available)o Etfective FEMA Flood lnsurance Study . FEMA HEC-RAS 1D Hydraulic Model of the Yakima River (covers the lower 5.5 miles of the Easton Reach). o Existing Yakima River Channel Migration Zone Analysis o Current and historical aerial photographs and maps r Recent and historical highwater marks o USGS National Land Cover Dataset Surficial soil data o River discharge data . River sediment grain size, supply, transport, and deposition data (if they exist). Design data for levees and revetments (if they exist) Assumptions: o The County will provide the Consultant with data they possess. T WATERSHED1+SCIENCE & ENGINEERING 1.2 L|DAR Topographic Data Collection The consultant shall collect LiDAR and photographic imagery as needed to produce highly accurate topographic data for the study area. lmagery collected during the L|DAR flight will facilitate the delineation of feature data (structures, roads, fence lines, etc.) throughout the study area. Acquisition of the L|DAR and imagery will occur under leaf-off conditions between approximately March 1Sth and April 1Sth, at a time when there is no appreciable snow cover. LiDAR collection will meet the assessments of statistical relative and absolute accuracy and meeting the guidelines of the National Standard for Spatial Data Accuracy (FGDC 1998 and SAPRS 2014) and meet the requirements for a QL1 USGS vertical accuracy specification. Deliverables: o Feature and Contour Data Layers in AutoCAD DWG Format or ArcGlS format. Digital Terrain Model (DTM) in AutoCAD DWG Format or ArcGlS Format. L|DAR Classified Point Cloud in LAS format - ground surface and first returnr L|DAR Raster DEM in ArcGlS Format at 3'-pixel resolution o 3-band 24-bit RGB Natural Color Orthophoto Tiles in Uncompressed TIF/TFW Formato 3-band 24-bil RGB Color Orthophoto Tiles & Mosaic in20 l Compressed SID/SDW Format . Flight lndex in AutoCAD DWG Format r Project Metadata (technical details) in standard PDF Formato Media Type: Standard Media (CD-ROM, DVD) Assumptions: r Ground control survey will be completed by the County 1.3 Project Kick-off Meeting and General Field Reconnaissance Consultant and County staff shall conduct a field reconnaissance of the project reach to discuss the project and examine key areas of concern (e.9., repetitive loss areas, potential avulsion and channel migration sites, the McElroy Road bridge, etc.) Deliverables: . Observations and photographs to be included in the project report Assumptions: o The inspection will last three hours. 2 WATERSHED++SCIFNCE & ENGINEFR'NC 1.4 Field lnvestigation The consultant shall conduct a field investigation to determine avulsion and channel migration characteristics of the project reach that may not be well captured by remote sensing (i.e. L|DAR) data. This will include observing: o Channel geometry (width, depth, slope) and planform. . Channel bed, bank, and floodplain substrate, including shallow (< 4 ft) hand soil probing as needed to determine the erodibility of floodplain substrate, following methods for channel migration and fluvial hazard assessment (Blazewicz et a|.,2020; Olson et al., 2014). . Deposited wood characteristics, such as porosity, blockage of channels, potential stability, and evidence of wood effects on channel evolution that could affect avulsion or channel migration potential, following published guidance on such characterization (Brummer et al., 2006; Livers et al., 2020; Scott et al.,2019; Wohl et al., 2010). The consultant shall utilize an unpersonned aerial vehicle (UAV), as needed, to collect low- altitude, high-resolution imagery of portions of the floodplain to supplement ground-based assessment. Assumptions: . County will obtain right of entry to private parcels as needed 1.5 Channel Survey Consultant will perform an in-water bathymetric survey within the upper 6 miles of the project reach to provide bathymetric data to support hydraulic model development. Cross sections will be collected at spacings of approximately 500 feet to provide a sufficient density to create a ground surface model and 1-foot interval contours. Survey will include key specific cross sections at controlling points along the river such as bridge structures. Consultant will combine the topographic surface derived from the LiDAR data and the bathymetric surface into one seamless digital terrain model (DTM) of the study reach, which will be used in Task 2.2. ln channel data for the lower 5 miles of the study reach will be based on channel data from the effective FEMA Flood lnsurance Study hydraulic model. Assumptions: o Surv€y will be completed between July and September, at a time when flows are low enough to support river wading. . The channel will be accessible by boat/wading. lf bathymetric data are required in areas not accessible by boat a change of scope and budget may be needed.o County will obtain right of entry to private parcels as needed Deliverables o Full topographic surface created by merging the bathymetric surface with the LiDAR data. . Surface will be provided in GIS format 3 1+ w,#lFn"?I'sR TASK 2 - HYDROLOGY, HYDRAULICS, AND GEOMORPHOLOGY 2.1 Hydrology The consultant shall develop discharge hydrographs for five flows including four that will be required to update FEMA maps. These are the 10-, 2-, 1- and O.2-percent annual-chance events (commonly referred to as the 10-, 50- and 100- and 500-year floods). The peak discharge for each hydrograph will match the peak value from the effective FEMA study unless the consultant determines that the peaks should be revised. The hydrographs will be applied to run the hydraulic model in unsteady mode which will improve the accuracy of results. The consultant shall also prepare a hydrograph and peak discharge for a 5O-percent annual chance event (2-year flood) which has a significant influence on channel shape and size. The 2-year flood will be run in the hydraulic model to help inform the Geomorphic (channel stability) Assessment. Deliverables for this task will be included in the project report: o Updated annual instantaneous peak flood frequency discharges if they ditfer from those used in the recent FEMA study. o Flood hydrographs for use as input to the hydraulic modeling & analysis. o ldentification and description in the project report of flood events that have caused significant geomorphic change. Assumptions: o The consultant will be able to obtain flow records from the Bureau of Reclamation. 2.2 Hydraulic Modeling The consultant shall use the topographic/bathymetric surface to develop an unsteady HEC-RAS 2D model covering the project reach. Model development will be completed in accordance with FEMA Guidance for Flood Risk Analysis and Mapping to support reach hazard assessment and FEMA map updates. This reach is extremely complex from a hydraulic perspective, and a2D hydraulic model will reflect that complexity to support identification and evaluation of hydraulic impacts, risks, and to prepare new FEMA maps. Key model inputs will include channel and floodplain topography (developed under Task 1 .2 and Task 1 .5) and existing land cover data from the USGS National Land Cover Dataset, The modelwill be calibrated to available high- water mark data (if it exists), then run to simulate the five flood hydrographs developed in Task 2.1. Results will be used to provide data required to evaluate hydraulic patterns and forces in order to predict future geomorphic change including channel avulsion and migration potential. Deliverables: o Model results in the form of GIS figures and tables will be included in the project report. Assumptions: . none 4 WATERSHED€+SCIfI{CE 8 ENGINEEPINC 2.3 Analysis and Review of Model Results The consultant will use model results from Task 2.2to prepare GIS based maps that illustrate simulated velocity, depth, and water surface elevations for each flood. These figures will be used to identify flood hazard areas and to support the geomorphic assessment. The consultant shall use the model results to develop public safety depth-velocity hazard maps for two of the five floods using criteria developed by the US Bureau of Reclamation described in 1988 Technical No. 1 1 Downstream Hazard Classification Guidelines. The floods to be mapped will be determined after the results of the five events are reviewed. Water surface elevation and inundation extents for the 1.0 and 0.2 percent annual chance events will be compared to the effective FEMA maps to determine if the results are significantly different. The effective FEMA maps are a composite of two different FEMA studies. ln 2021 FEMA completed HEC-RAS 1D hydraulic modeling of the lower 5.5 miles of the Easton Reach to support Countywide floodplain map updates, while mapping for the upper 6 miles of the reach is based on a study published in 1981 . The consultant and County staff will meet to review the model results to identify and discuss flood hazard areas and to determine whether the FEMA maps should be updated through a Letter of Map Revision (LOMR). Compilation and submittal of a LOMR request is covered by optional Task 4 below. Deliverables: . Model results - velocity, depth and water surface elevations presented as GIS layerso Graphics showing differences in water surface elevations and flood inundation extents between this study and the etfective FEMA maps. o Depth-velocity hazard maps for two events. Assumptions: o Deliverables will be presented in a meeting with County staff and in the project report. The meeting is included in Task 10 below.o Final floodplain inundation and depth-velocity hazard maps will be provided to the County in a format that can be uploaded to the County's existing GIS database. 2.4 Bridge Hydraulic Evaluation Three private bridges cross the river within the project reach - the McElroy Road Bridge, the Sun lsland Road Bridge, and the Ellensburg Cement Products facility bridge. Each bridge will be included in the hydraulic model developed under Task2.2. For Task 2.4the modelwill be updated to remove the bridges and associated road fills and then run to simulate the peak flow hydrographs developed under Task2.1. Model results (without bridge) will be compared to results from Task 2.2 (with bridges) to understand the impact each bridge has on flooding. GIS figures will be created to show differences in velocities, depth, water surface elevations, and flood inundation extents for up to three of the five flood events. The consultant shall use this information to evaluate whether each bridge provides adequate conveyance capacity or constricts flow in a manner that impacts access and evacuation capabilities, which would create additional risks to the public, residents, emergency responders, structures and infrastructure. 5 WATERSHED+SCIENCE 8 ENGINEERING The consultant shall use the hydraulic model to identify hydraulic conveyance improvements that are required for the McElroy Road crossing. On December 13,2021, the McElroy Road Bridge collapsed during a flood. Local and state authorizations were granted to re-installed the bridge for temporary use with the stipulation that permanent solution will need to be found. Sufficient flood conveyance is required to ensure that the crossing provides reliable access to emergency responders and evacuation of residents during floods. The consultant shall use the hydraulic model to identify, at a conceptual level, the size of waterway that will be required to provide reliable access and meet local and state hydraulic requirements. Deliverables: . Figures showing the impact each bridge has on velocity, depth, water surface elevations and inundation limits. Figures will be produced for up to three of the five floods.r Figure showing the approximate size of the hydraulic opening required for the McElroy Road bridge. Assumptions: . The results of the bridge evaluation will be presented at the same meeting as the model results in Task 2.3. The meeting is included in Task 3.1 below.o The McElroy Road bridge watenruay will be presented as a conceptual sketch intended to provide the community and County with a general understanding of the length and height of the new crossing that will be required to provide reliable access and meet local and state regulatory requirements. No civil, structural or geotechnical design activities will be performed. 2.5 Geomorphic Assessment The consultant shall conduct a geomorphic assessment to:o ldentify and describe the geomorphic processes that currently shape the project reach and how human modifications (flow regulation, levees and revetments, bridges, etc.) alter those processes. o ldentify past hydrologic events have been responsible for generating significant geomorphic change to describe the relationship between flow and the historical geomorphic evolution of the reach. o lf needed, depending on migration since the last channel migration zone assessment and the extent of that assessment, measure the rate of historical channel migration within and surrounding the project reach to determine typical channel migration rates, patterns, and controls, if possible, to inform an assessment of channel migration hazardo Assess historical aerial imagery, L|DAR, geologic map data, and field observations to determine the prevalence and typical character of avulsions within the project reach, including the influence of large wood. o lnterpret hydraulic model outputs to inform channel migration and avulsion hazard assessments. . Map potential avulsion pathways through the floodplain to identify specific potential avulsion risks. 6 1+ y,.fJF*"s#sP a Create hazard maps for the project reach, refining the existing channel migration zone assessment to detail specific zones, potential rates, and controls on channel migration and avulsion hazard. The geomorphic assessment methods will be based on best practices for fluvial risk assessment (Blazewicz et al.,2020; Olson et al., 2014). Deliverables: o Text and figures that present the results of the geomorphic investigation to be included in the project report. o Draft and final channel migration hazard maps. o Draft and final avulsion hazard maps. Assumptions: o Hazard maps will be developed to a level of detail that is appropriate given to the degree to which past channel evolution can be explained in terms of geomorphic and anthropogenic influence. . Deliverables will be presented in a meeting with County staff and in the project reporl. This meeting is included in Task 3.1 below. . Final channel migration and avulsion hazard maps will be provided to the County in a format that can be uploaded to the County's existing GIS data base. 2.6 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: n Project goals, objectives, and constraints. o Descriptions of existing hydrologic, hydraulic and geomorphic conditions. o ldentification of areas of high flood and geomorphichazard. Deliverables: o Draft and final report. Assumptions: . County staff will review the draft report and provide a single set of comments to the Consultant. o The Consultant will address the County comments in the final report. 7 + y,#lFa"s,.T,-EP TASK 3 - MEETINGS AND ADMINISTRATION 3.1 Meeting with Gounty Staff to Review lnvestigation Results Up to four meetings will be held between consultant and County staff to review and discuss the results of the investigation. These include: 1. Meeting to review initial hydraulic model results produced in Tasks 2.3 and 2.4 above. 2. Meeting to review initial results of the geomorphic assessment in Task 2.5 above. 3. Meeting to review any updated results that reflect refinements suggested by the team during meetings 1 and 2 above. 4. Meeting to discuss and prepare for the Community Meeting (Task 3.2 below). Deliverables: o GIS graphics of the model results. o Draft Power Point presentation slides to be included in the Public Meeting presentation. Assumptions: . Consultant and County staff shall participate (virtually) in up to four 2-hour video conference calls to review the results. 3.2 Community Meeting Consultant shall support County staff and participate in a meeting with the Elk Meadows community to share study results including flood, channel migration and avulsion hazard maps. Deliverables: o Power Point slides to be included in the County's presentation. Assumptions: o Meeting will last three hours. o The County will organize and lead the meeting to present the assessment results. 3.3 Administration The consultant shall perform typical administrative duties by communicating regularly with the County's project manager, monitoring schedule and budget, and submitting monthly invoices. 3.4 Administrative Reserve An administrative reserve is included to allow WSE to address additional questions or issues that may arise during project execution, review or coordination. This may include additional analysis, modeling, meetings, presentations, documentation, or discussion. Administrative reserve funds will only be used following expressed written direction from the County. 8 WATERSHED4+SCIENCE & ENGINEERING TASK 4 . LOMR DOCUMENTATION, SUBMITTAL, AND FEMA COORDINATION 4.1 LOMR Documentation The consultant shall provide data, documents, and other information required by FEMA to process a Letter of Map Revision (LOMR) request to update FEMA flood hazard mapping within the Easton Reach. Specific tasks and deliverables will include: . FEMA Flood Modeling: The 2D model (Task 2.2) will be updated to delineate a FEMA compliant floodway based on FEMA guidance for Flood Risk Analysis and Mapping.o Floodplain Mapping: Consultant will map the 1- and 0.2-percent annual-chance floodplain boundary delineations, FEMA floodway boundary delineations, base flood elevations (BFEs), cross-sections referenced to consistent river mile designations, flood insurance risk zone labels, and all applicable base map features for the study area.e Document Methods and Assumptions: Consultant will provide written documentation to describe the methods and assumptions used in the hydraulic analyses, modeling techniques, model calibration, and floodplain and floodway boundary delineation.. Tabular Summary: Consultant will provide discharge, water surface elevation, and other pertinent floodplain data in tabular form listed by cross-section, This will include a discussion how proposed 1-percent annual-chance floodplain and floodway boundaries will tie into the existing flood studies adjacent to the study reach.o Compile Map Update Application Materials: Consultant will compile flood profiles, floodway data tables, a topographic workmap, annotated FlRMs, and study documentation for County review and submittal to FEMA. 4.2 FEMASubmittalandCoordination o WSE will out and complete required (MT-2) application forms and submit the LOMR to FEMA through the FEMA online letter of map change portal. o WSE will support the LOMR through FEMA's review process by responding to requests for additional information. WSE will provide requested data which may include minor changes to submitted modeling or materials described in Task 4.1.r Community Notification Support: Consultant will support the County in addressing appeals or comments received following community notification of proposed updates. Assumptions: o lt will be free to submit the "LOMR Based Solely on Submission of More Detailed Data".o FEMA's review will follow a typicaltimeline for review and acceptance (6-9 months from submittal to acceptance). 4.3 LOMR Task Administration WSE shall perform typical administrative duties associated with the LOMR task including communicating with the County, monitoring schedule and budget, and submitting invoices. Schedule Task 1-3 will be completed by December 31, 2022 Task 4 will be completed by December 31,2023 9 WATERSHED€+SCI€NC€ & ENGINEERING References Blazewicz, M., Jagt, K., & Sholtes, J. (2020). Colorado Fluvial Hazard Zone Delineation Protocol Version 1.0. Colorado Water Conservation Board. Brummer, C. J., Abbe, T. B., Sampson, J. R., & Montgomery, D. R. (2006). lnfluence of vertical channel change associated with wood accumulations on delineating channel migration zones, Washington, USA. Geomorphology, 80(34), 295-309. https://doi. o rgl 1 0.10 1 6/j. geomorph.2006. 03. 002 FEMA (2016). Guidance for Flood Risk Analysis and Mapping. Federal Emergency Management Agency, Guidance Document 52, November 2016 Livers, B., Lininger, K. B., Kramer, N., & Sendrowski, A. (2020). Porosity problems: Comparing and reviewing methods for estimating porosity and volume of wood jams in the field. Earth Surface Processes and Landforms, esp.4969. https://doi.org/10.1002/esp.4969 Olson, P. L., Legg, N. T., Abbe, T. 8., Reinhart, M. A., & Radloff, J. K. (2014). A Methodology for Delineating Planning-Level Channel Migration Zones (Publication no. 14-06-025). State of Washington Department of Ecology. Scott, D. N., Wohl, E., & Yochum, S. E. (2019). Wood Jam Dynamics Database and Assessment Model (WooDDAM): A framework to measure and understand wood jam characteristics and dynamics: Wood Jam Dynamics Database and Assessment Model (WooDDAM). River Research and Applications. https://doi.orgl10.1oO2lrra.3481 Wohl, E., Cenderelli, D. A., Dwire, K. A., Ryan-Burkett, S. E., Young, M. K., & Fausch, K. D. (2010). Large in-stream wood studies: A callfor common metrics. Eafth Surface Processes and Landform s, nl a-nla. https://doi. org/1 0. 1 002/esp. 1 966 10 €+ y,sJFa.s,#.FR *+WATERSHED SCIENCE & ENGINEERING Estimate of Professional Services Prepared for: Kittitas County Project: Easton Reach Yakima River506 2nd Ave, Suite 2700 Seattle, WA 98104 Tel. (205)521-3000 Hazard Mapping Study March7,2022 Jeff Johnson, Chris Frel, Dan Scott Date: Prepared By: rASK DESCRIPTION Hou6 Totalssr. geom.tsno,Jr, Eno 1.2 LiDAR ToDooraohic Dala collection E 1.3 Prolect Krcl(-On l4eelrnq And General Fielcl Reconnaissance E $5 071 1.4 Fteto tnvesltoaton 2 50 $12.774 1 5 Channel Suruev 80 Silbthlt 0 20 68 148 2 Hyorolooy. Hvdnulrcs. and Geomorpholoqv 2.1 Hydrolooy 4 20 4.47Q2.2 HydraulicModeling 4 4 36 120 60 1 26,699 36 7 670 2.4 tsfldOe HVdraultc tsvalualon 24 5741 2.5 GeomorphicAssessment 4 100 60 I 20.428 2.6 Technicel Reoorl 40 Subtolt 240 3.1 Meeting with County Slalf lo Review lnvestiqation Resulls E '12 12 3.2 Communitv lt/leetino 16 2 6 1 723 4 LOMR ComDilation and Submittal 4.1 LOMR llocumentation 60 40 20 681 4.2 IEMA Submftal and goordrnalDn 4 30 24 12 573 4 3 LOMR TeskAdminiskalidn 120 fotal Hours and Direcl Labor Cost (DL) -abor Rate ($/hr, July 2021 WSDOT OH 150.07%, 30% protit on DL) rOTAL LABOR COST $15,754 $1,454 $38,038 $32,880 $62,300 256.O Direct Detail Cost It ilsage Lodging and Per Diem Field Data Collection Suruey Equipment Renlal L|DAR and Base Map (GeoTerra) 3% Markup on Subconsultant 3,000 2,500 45,000 1,350 1000 $0.s85 Total $52,i|35 $ $Tolal Direcl Expenses Total Labor Total $215,281 192,826 52,435