Loading...
04/24/2012 02 Gap-to-Gap Floodplain Restoration Project Presentation , r .,, BUSINESS OF THE CITY COUNCIL YAKIMA, WASHINGTON AGENDA STATEMENT Item No. For Meeting of: April 24, 2012 ITEM TITLE: Gap -to -Gap Floodplain Restoration Project presention by Wastewater Manager Scott Schafer SUBMITTED BY: CONTACT PERSON /TELEPHONE: SUMMARY EXPLANATION: Resolution Ordinance Other (specify) Contract: Mail to: Contract Term: Amount: Expiration Date: Insurance Required? No Funding Phone: Source: APPROVED FOR SUBMITTAL: C Manager STAFF RECOMMENDATION: BOARD /COMMISSION RECOMMENDATION: ATTACHMENTS: Click to download El Gap to Gap presentation City of Yakima Floodplain Restoration Outfall Alternative *OS j. • IOW 4 al la - \ - Incorporating Wastewater Treatment Infrastructure and the "Gap to Gap" levee removals in the Yakima River Yakima Regional Wastewater Treatment Facility: Currently allowed to discharge treated wastewater to Yakima River under the conditions of a mixing zone described in its National Pollutant Discharge Elimination System (NPDES) Permit: B. Mixing Zone Descriptions The maximum boundaries of the mixing zones are defined as follows: The length of the chronic and acute mixing zones shall extend downstream no greater than 310 feet and 31 feet, respectively. The width of the chronic and acute mixing zones shall be no more than 50 feet wide. The aquatic life -based dilution factors for the chronic and acute mixing zones were determined to be 10.12 and 1.86, respectively. Mixing zone available because the river is held in place by the Sportsman's State Park Levee and the City of Yakima WWTP levee .. • for now. - v • ( ,� y 9. r i r Gap to Gap • Gap to Gap: multi- agency effort to set back levees in the Gap to Gap reach since the late 1990s • 10's of millions of dollars have been spent — US Bureau of Reclamation- "Reaches r` Study" and land purchases " — WSDOT- Longer bridge span on HWY 24 — Yakima County- Flood Control Zone District and Boise Pond work — Army Corps of Engineers- decision to not repair Sportsman's State Park Levee, but to build set -back at old KOA campground City of Yakima Levee and Greenway- Spring 2011 • 'F� 1 " �11 • � r § g 8• / I (.. # r ..• r \ghee' c \ Milli • �r■y i I' Qty 4 _ - 1 i l / Jr ` c ._ 4 i . t , iti r \..............., fir ' _ °'" N • •� :lir! � • J. lt. - Lt .r , - 19 1 •r'1, • • • • c R a • y • r • . I / ' / ti r �, • - p union G ap 1 , c ' ' Goo� A • -� ' E �:1 �Jneiaip • Gap to Gap and the Regional Wastewater Treatment Facility • City of Yakima has requested for Gap to Gap activities to undergo sufficient environmental review in order to identify mitigation measures for loss of outfall /mixing zone. • An EIS /EA that evaluates impact of Gap to Gap on outfall has not been done. • Most recent activity was a major levee setback that was conducted without review because it was declared an emergency. Now, the river will eventually flow through the old levee r ... „:„,,,...... tt.. ._ r r te - :� \ ._ y... It _ - ! -- October 2011 March 2012 s k, j April 2012 City of Yakima Regional WWTP outfall Alternative • Move outfall to a series of restored fish bearing habitat features compatible with goals of gap to gap. — Phase 1: Restore Billy's Pond- Funded with State Salmon Recovery Funding Board — Phase 2: Re -route Greenway trail past restored pond site and out of floodway — Get Ecology approval for extended mixing zone — Phase 3: Discharge effluent diagonally into restored flood channels Funding and Timeline • Phase 1- Funded with SRFB money • Phase 2- Started application for SRFB money • Working with Ecology- putting together engineering report • Phase 3- Presently un- funded City Property Restoration Costs •Apply and receive Salmon $275,400 SRFB Recovery Funding Board Grant for Phase 1 $ 15,000 ytahp •YTAHP Project Funding /Match .Hire Ridolfi Engineers for $802,000 SRFB 2012* restoration design and engineering report $250,000 ECY 2012' . Sub Total $1,682,000 Complete conceptual design for project. •Complete Engineering Report for Department of Ecology Review *Start permitting Moving Outfall Distribution $1,500,000 •Begin design of Phase 1 Engineering Costs $ 500,000 •DRAFT facility plan for WWTP •Apply for Phase 2 Funding from SRFB and Ecology •Complete design work Complete permitting •Go to bid in late Estimated project cost $ 4 Million to $5 Million winter /spring 2013 Summary • Gap to Gap — Lowers flood damage risk — Improves fish habitat — Improves water quality — Affects City Wastewater Infrastructure • Wastewater supports Gap to Gap so long as impact on ratepayers is minimal J:/01/ ed 11 4) - ' _ d-b/ i EXECUTIVE SUMMARY The Comprehensive Flood Hazard Management Plan (CFHMP) for the Ahtanum and Wide Hollow basins covers two urbanizing flood -prone basins in the cities of Yakima and Union Gap, and Yakima County to the north of the Yakama Nation boundary. The Ahtanum -Wide Hollow Comprehensive Flood Hazard Management Plan is the third flood hazard plan to be developed in Yakima County by the County -wide Flood Control Zone District (FCZD). The FCZD develops flood hazard management plans to prioritize flood hazard mitigation actions, support County and City staff in the floodplain communities, and develop partnerships across the various agencies and jurisdictions on projects within floodplains. The purpose of a CFHMP is to propose a suite of actions that will reduce identified flood hazards over both the short and the long term. A CFHMP is a policy document which contains recommended policy changes and flood actions, including projects that reduce flood hazard. Answers to the questions "What types of actions will be effective ?" and "Why will these actions be effective ?" are the critical components of an implementation strategy contained in the plan. The Plan provides a basis for flood hazard risk management by the jurisdictions in the Ahtanum and Wide Hollow basins. Flooding is a natural phenomenon, frequently exacerbated by human practices, that cannot be entirely prevented. There are many approaches to protect lives and property while protecting the environment and natural resources of the community. The recommendations of this Plan sought to find the greatest public benefit at the least cost over the short and long term. A citizen and agency Advisory Committee was formed and 48 meetings held to assess hazards, develop the CFHMP goals and objectives, and to develop the CFHMP alternatives and recommendations. In addition, there were four public workshops, providing extensive local contribution to the flood knowledge, potential solutions and plan development by citizens, the two cities, Yakama Nation and all affected public agencies. Approval by the Washington State Department of Ecology and endorsement by FEMA will allow local jurisdictions who adopt the plan to become eligible for state and federal funds for flood emergency response and non - emergency activities to reduce property loss and threats to human life. Infrastructure modification or replacement projects identified within a CFHMP are eligible for funding through disaster grants. Without a plan, infrastructure is normally replaced or repaired to pre -flood conditions and may fail again. With the plan, infrastructure can be modified or replaced in a manner that produces overall reduction in flood hazards to the structure and surrounding area. The plan contains twelve chapters and supporting appendices. The chapters are divided into four sections; Chapters 1 and 2 delineate plan process and community involvement, Chapters 3 through 6 provide the physical and regulatory setting, Chapters 7 and 8 concentrate on flooding characteristics and Chapters 9 through 12 provide the plan alternatives, recommendations, funding and strategy. I II Ahtanum -Wide Hollow Draft CFHMP Basin Flood Impacts In 1974 the Ahtanum and Wide Hollow basins experienced a 200 -year flood, as estimated from Ahtanum Creek stream records. In 1996, the Ahtanum basin experienced an 80 -year flood while the flooding on Wide Hollow Creek was less severe. These two major flood events, only twenty -two years apart, may turn out to be more frequent than the above probability estimates would indicate. The flood damages in 1996 were more severe than in 1974 since the basin and floodplains had undergone more urban development. Total County -wide damages in 1996 were $18 million with severe public and private damages in these basins. In response the County engineer designated these basins as flood prone and requires higher drainage standards that the cities have also adopted. The continued conversion of land use from rural to urban during the intervening period has increased flood risk exposure. This has been demonstrated in recent economic analyses for federal flood hazard grants that are noted in the plan. Floodplain Land Use and Channel Conversion Impacts The communities of Yakima, Union Gap, Ahtanum, Wiley City, and Gromore were located near these creeks due to productive soils available for agricultural and easy access to groundwater. These areas were settled before extensive flood experience had been accumulated. The City of Union Gap is located at the Yakima River confluence of these two creeks and encountered historic flooding and related development constraints. The City of Yakima, protected by levees from the Naches and Yakima rivers built after World War II, has more recently expanded into flood prone areas as a result of westward annexations. Prior to the expansion, much of Yakima was located west of 16th Avenue on high ground. A high proportion of the remaining developable land within the Urban Growth Areas of Yakima and Union Gap is low lying former agricultural land with high groundwater, in or near the floodplains. Agriculture is very productive in the flat valley bottoms of these basins. With the advent of large scale irrigation systems many channels were moved to the higher valley side slopes. In this location, channels and ditches could be used to irrigate the adjacent lower farmland. In other cases creeks were covered over or directly converted to ditches. The designers of early irrigation systems took advantage of the geologic tilting of these flat valleys to create irrigation systems extending across broad expanses of the valley in both basins. These systems designed for irrigation also route flood waters. This increased the number of flow paths and extent of shallow flooding over natural conditions. These flood paths are only rarely active, and therefore the flood risks associated with these areas are not easily recognized by the public, private institutions, and public agencies, until after a flood occurs. Where flood paths remain in agricultural use, only minimal damage occurs. When land is converted to higher density urban use significant damage can, and has, occurred. The use of the creeks to convey irrigation flows has led to "artificial hydrographs" and the proliferation of vegetation in the channels that obstruct flow, trap sediment and reduce channel capacity. Management of the irrigation systems themselves is also EXECUTIVE SUMMARY I III increasingly difficult as large parcels are broken up through the urbanization process. This change reduces the frequency of maintenance and types of maintenance approaches for irrigation channels. Both the increases in vegetation and changes in the level of maintenance tend to reduce the capacity of irrigation channels, which include both artificial channels and highly modified "natural" channels such as Wide Hollow, Bachelor and Hatton Creeks. This increases the frequency and severity of "nuisance flooding" in these drainages. Urban road infrastructure also tends to exacerbate flooding, especially when located across relocated channels that promote flood overflow paths. Flood waters may be dammed or routed by roads or along roads. As the density of the road system has increased to meet urban needs, more bridges have been required. There are the over 80 public bridges plus a larger number of private bridges in the basins that have the capacity to deflect flow. Most of the road infrastructure was constructed and sized prior to the 1974 flood. Because of the above conditions, minor changes to the topography (road, fence, large buildings, fill, and beaver dams) can, and often do, change how flood waters are routed across the floodplains. The 100 -yr flood maps and history of flooding show the redirection of flood flows across extensive tracts of land, that present a large flood hazard. These channel flow redirection concerns were addressed in the development of alternatives and recommendations. Economic implications of this progressive land use change are also considered in the plan. A compilation of flood location data is presented in Chapter 2. Plan Scope and Process The plan is comprehensive as it incorporates the entire watershed, as much community input as possible and practical, and because it aims at short and long term solutions that have been prioritized.. The structural flood hazard solutions frequently chosen in the past to protect current development have constrained the river at great community expense and exacerbate the extent of flooding over the long term, or have impacted development downstream. Through a comprehensive plan these effects are well understood before flood control actions are taken that could worsen the situation through redirection of flows. The CFHMP is guided by a Department of Ecology process that identifies flood vulnerabilities and risk, and provides recommendations to mitigate community flood impacts. The CFHMP process seeks to involve a broad spectrum of local people and interests in the development of a plan and allows the community to carefully consider and prioritize alternatives for flood hazard management. Recommendations include both traditional structural solutions, such as channel realignment, and non - structural solutions, such as regulations or elevation of homes, to reduce flood exposure. CFHMPs address flood hazard only and review the current community GMA and related mechanisms effecting flood management and regulation within the plan geographic extent (see Chapter 8). The non - structural CFHMP recommendations can be IV I Ahtanum -Wide Hollow Draft CFHMP incorporated in the Growth Management Act (GMA) Comprehensive Plans, including capital facilities plans, through inclusion of Hazard goals (see Table 1.1 in Chapter 1) and through modification of planning requirements and ordinances for development within floodplains. CFHMP Goals and Objectives Defining goals and objectives provides the framework for carrying out the CFHMP. The goals and objectives were generated by the Advisory Committee following the inventory of physical conditions, are provided in Table ES -1 below. Goals reflect the broadest expression of the community's desires in preparing the plan; objectives target specific results that fulfill the intent of the goals. Table ES -1. GOALS AND OBJECTIVES FOR AHTANUM -WIDE HOLLOW CFHMP Goals (to be achieved Objectives through objectives) • Identify the location of critical conveyance channel locations • Identify stream reaches which have lost flood conveyance capacity due to changes in streamside vegetation or by human activities • Assess existing roads, bridges and culverts for barriers to flow- through and 1. Identify flood areas potential abatement of flood damage and flood processes • Identify past erosion and stream migration processes and monitor after storm events • Understand and protect the natural function of the system to reduce flood hazard • Determine risks and potential mitigations for hollows • Identify structural and non - structural actions for reducing flood hazards that recognize the corridor as a resource and are consistent with long -term river corridor functioning • Develop flood hazard management alternatives and strategies to reduce long -term damages • Develop short-term flood hazard reduction alternatives consistent with long- term strategies 2. Reduce flood • Prefer mitigation recommendations that provide benefit for multiple problems damages to citizens, and /or locations or enhance the value of the stream corridor as an asset to property and the community infrastructure while • Improve predictability of channel response to flood events maintaining natural functions of stream • Evaluate impacts of present management of flood control and irrigation and floodplain diversion structures during flood events, such as the flood gate on Spring systems Creek in Union Gap • Create inundation maps for flood evacuation preparedness • Conduct training at first responder and jurisdiction level using Flood Response Plan • Facilitate coordination with Emergency Management and Public Works Agencies before, during and after floods (Flood Response Plan) • Complete flood forecasting and warning projects in the basin and integrate with Emergency Response EXECUTIVE SUMMARY I V Table ES -1. GOALS AND OBJECTIVES FOR AHTANUM -WIDE HOLLOW CFHMP Goals (to be achieved Objectives through objectives) • Protect existing, or enhance where possible, fish and wildlife habitat • Protect the natural function of the system to reduce flood hazard 3 Work within the • Evaluate the use of setback dikes to allow for a more naturally functioning physical and floodplain biological processes • Restore creeks to more natural channel (i.e. instream projects to address 90 in the floodplain degree angle corners and channels "perched" high on landscape) • Consider mitigation at watershed level or at a minimum reach level across jurisdictional boundaries • Use best available flood hazard data for regulation of land development and permitting • Show critical areas and floodplain areas on plat maps corresponding to short/long plat developments (see City of Yakima regulations) • Conduct restudies of FEMA floodplain maps • Ensure that land use plans and regulations protect floodplain functions • Evaluate and ensure County /City enforcement of land use regulations 4 Achieve land use • Coordinate with Yakama Nation on enforcement of land use regulations practices that • Evaluate other development requirements that may impact flood hazard respect floodplain management, such as septic systems and water well siting functions • Ensure consistency of floodplain regulations within jurisdictions and investigate increasing the consistency between jurisdictions. • Identify and implement incentive program for bioengineered structural solutions to flood hazard mitigation • Work with existing permitting agencies (such as, Fish and Wildlife, USAGE, Yakima County Shoreline, Ecology, and the Yakama Nation Water Code Administration) on identifying ways to streamline project permitting process • Encourage coordination and cooperation among all regulatory agencies • Work in creative ways to streamline the regulatory process • Encourage innovative development techniques where natural systems and floodplain function exists 5 Emphasize the value of stream corridors • Educate the public and development community on the value of allowing as an asset to the floodplain and stream function to properties- investigate Smart Growth community concepts • Encourage open space planning and acquisition, through incentives such as leases, easements, acquisition, etc. • Identify erosion and stream migration hazards and evaluate mitigation options as necessary • Create and submit FEMA floodplain map for Shaw Creek • Sustain the mapping program • Compile varied available mapping data into a comprehensive database /library resource that can be used to address future assessments 6. Quantify hazards in • Identify changing flood condition areas to support new floodplain mapping our floodplain work • Identify draws that are prone to flash flooding • Avoid contaminating land uses in the floodplain • When designing a flood overflow area, make sure it is not a contaminated area • Minimize impacts of septic systems and other critical facilities on water quality VI Ahtanum -Wide Hollow Draft CFHMP Table ES -1. GOALS AND OBJECTIVES FOR AHTANUM -WIDE HOLLOW CFHMP Goals (to be achieved Objectives through objectives) • Communicate and coordinate with local governments and community groups on flood issues /hazards • Provide documented examples of positive steps being taken • Highlight projects that will educate the public on sustainable flood hazard 7 Ensure a sustainable mitigation flood plan through • Ensure an ongoing educational program that keeps up with current public and agency understanding, science, and changes in the watershed awareness, acceptance, • Participate in the CRS (Community Rating System) program involvement, and • Flood safety preparedness education education • Determine where large numbers of animals may be kept during a flood event and distribute information to the public • Develop a stream corridor improvement program consistent with this plan • Increase public awareness and understanding of flooding issues and floodplain functions • Seek grant funding • Investigate possible cost savings through coordination with other multiple objective projects • Determine possible areas for flood control sub -zones 8 Ensure the • Address the causes of problems as opposed to the symptoms implementation of the flood plan in a • Identify and utilize complementary Plans timely manner for • Consider flood related recommendations from large scale plans such as the both the short and Ahtanum Watershed Assessment long term • Integrate flood hazard reduction into ongoing planning, management programs, and capital facilities plans • Understanding how the landscape is managed • Create and implement educational efforts to inform other organizations about flood risks, plans, and possible mitigation approaches These flood hazard goals and objectives are achieved by the plan development process and subsequent implementation of the plan recommendations. FEMA 100 -Yr Floodplain Remapping During the development of the CFHMP the FEMA Flood Insurance Study (FIS) revised the flood insurance rate maps (FIRMs). The accuracy of the old FIRMs for Ahtanum and Wide Hollow Creeks had been under question following the 1996 flood. The previous FIRMs were generated in the late 1970's and published in 1985. Remapping of these two creeks was initiated under the nation -wide FEMA Map Modernization program starting in 2004. As part of the CFHMP the combined Steering and Citizens Advisory Committee, along with the FCZD, municipalities and citizens, came forward to contribute to the accuracy of the new FIRMs flood maps through direct input on historic flooding. A major focus was the identification of overland flow paths. This process also assisted in the development of the CFHMP. The flooding impact of various factors such as vegetation, bridge sizing, sediment buildup at bridges and agricultural infrastructure could be evaluated using the FEMA hydraulic models. The EXECUTIVE SUMMARY I VII draft CFHMP was initially delayed to allow the Advisory Committee to view the preliminary FIRMs in order to refine CFHMP alternatives and recommendations. The FIS Preliminary Maps for the new Wide Hollow Creek FIRMs were released to the cities of Yakima and Union Gap in October 2010, followed by Ahtanum Creek FIRMS in October 2011. The maps will be finalized in 2011 or 2012, respectively, depending on the appeals process. The hydraulic models for both basins are available from the FCZD and can be used for future studies and proposed or revised infrastructure. Use of the FEMA models to evaluate sediment management at bridges revealed that modifying the existing bridges would not resolve the overflow path problems for 100 -yr floods, as originally hoped. A stronger non - structural approach than originally envisioned during goals and objectives formulation, and one that addresses more frequent floods at, or less than, the 25 -year flood, would be required in order to protect future development. Flood Hazard Management Recommendations The plan recommendations focus on damage prevention to future and existing development in order to reduce costs, including flood insurance fees. Many of the recommendations will provide relief for both future and existing development. The plan recommendations contained in Tables ES -2 and ES -3 were designed to incorporate parallel objectives of multiple parties to facilitate implementation and maximize benefits. Partners have been added to the recommendations as a separate column in recognition of the need to coordinate ongoing activities across agencies, to leverage funding, and conduct long term planning of new and replacement infrastructure. Priorities provided in the tables were based on issues of flood benefits, threat and expediency. The jurisdictions and agencies will determine their final priorities in this regard. As priority does not fully convey the capability to implement, an onset timeline for implementation was designated and added to the recommendations. The use of this designation also provides an initial strategy for community implementation of the plan. Actions completed by the FZCD are denoted "C" for "completed" and contained in Chapter 10 and the Appendices. Actions already underway, usually by the FCZD (see Chapter 10), are denoted IP for "in progress ". Actions recommended to be initiated shortly after Plan adoption are denoted S for "short term ", while L is for "long term ", again referring to start date. Actions recommended within the next cycle of regulatory update, such as Comprehensive Plan or Ordinance updates are denoted as AU for "awaiting update ". Actions recommended to be initiated as part of upcoming projects or opportunities are denoted 0 for "opportunity ". To guide implementation, recommendations were grouped into categories. Recommendation categories indicate the work nature and main partners required for VIII I Ahtanum -Wide Hollow Draft CFHMP implementation. The categories are: Inventory and Study, Planning and Regulatory, Maintenance and Management, Structural, Public Outreach, and Flood Response. For example, the FCZD cannot take the lead for Planning and Regulatory, a role that belongs to the jurisdictions. The FCZD can facilitate Maintenance and Management for facilities and lands that belong to landowners and jurisdictions. The FCZD has already taken a major role in Public Outreach and Flood Response. Implementation of Public Outreach recommendations will require an ongoing, coordinated approach to planning, regulatory, structural, and maintenance actions and programs over the long term. The flood hazard definition and mitigation recommendations are summarized in tables ES -2 and ES -3, respectively. Inventory and Study recommendations within Table ES -2 will fill information gaps and may refine flood hazard mitigation recommendations within Table ES -3. Many of these Inventory and Study recommendations are currently in progress, and those complete are noted and included in the appendices. Additional details on these recommendations and estimated costs are provided in Chapters 9 and 10, respectively. The largest proportion of costs is for structural recommendations; the high priority structural recommendations are estimated at approximately $5 million dollars. ES -2 Recommendations for Further Flood Hazard Definition INVENTORY AND STUDY Description Onset Priority Partners IS - Establish technical work groups and pilot programs on IP H FCZD/WDFW Irrigation a reach by reach basis for channel, vegetation and sediment Districts, Landowners, maintenance (including Wide Hollow coarse sediment Jurisdictions budget), to develop criteria and enable appropriate larger scale maintenance programs which meets flood and habitat needs. (See Appendix J) IS - Establish cleanout guidelines and a pilot program C H FCZD/ Roads, Plan bridge sediment removal & maintenance. (See Appendices Depts G &H) IS - Inventory problematic bridges, roads and infrastructure IP H FCZD/ Roads Depts impacts and sediment buildup to generate action plan for removals, etc. This includes areas of ponding. IS - Inventory flooding impacts for existing and abandoned IP H FCZD/ irrigation structures. Irrigation IS - Modify bridge crossing design to reduce flooding and IP H Roads/ Plan Depts maintenance on case to case basis — wider spans, wider easements upstream and downstream for channel design and cleanout, deeper footings, to enable for scour, etc. (See Appendix G) IS - Wapato dam impact assessment for Union Gap IP H FCZD IS - Provide 10 and 25 year flood extent maps to show C H FCZD chronic flooding areas where actions such as infrastructure sizing and siting, proposed development and redevelopment can be designed to guide flood hazard reduction. (See Appendix J) IS - Provide 10 and 25 year flood damage estimates using IP H FCZD established federal methods to guide economic and environmental decisions. EXECUTIVE SUMMARY I IX INVENTORY AND STUDY (cont) Description Onset Priority Partners IS - Study to identify Ahtanum avulsion scenarios and S H FCZD existing flood issues at Mission. IS -10 Establish historical flooding areas —e.g. Wiley City & S H FCZD /Plan Depts Ahtanum -as special study areas to include all infrastructure. IS -11 Establish historical map and identity flood risks in S H FCZD Hollows. IS - 12 Identify & prioritize emergency response access S H City & County routes during 10, 25 and 100 year floods to incorporate into Roads/YVOEM emergency transportation and planning. IS - 13 Resolve run -off issues presented by DIDs. S M Jurisdictions IS - 14 Document floods including aerial photos, high water S M FCZD marks, etc. IS - 15 Identify high flood risk stream reaches where man- S M FCZD/ WDFW made changes or proposed projects effect channel processes or flooding including roads, perched channels and other alterations IS - 16 Design bridges and irrigation infrastructure to reduce L M Roads/FCZD Plan potential for accumulation of debris and sediment and Depts, WDFW creation of un- natural overflow channels /paths. IS - 17 Study use of ring dikes to protect St. Joseph's Mission IP L Landowners property IS - 18 Consider major levee construction on Mission IP L FCZD property to alleviate headcuts, this may not be needed if Recommendations A & B in Hatton section are successfully implemented. IS - 19 Perform an Emma Lane flood study, and develop IP L FCZD design guidance on acceptable flood protection levels. (3 -2). Address Ahtanum Creek flood conveyance downstream of 42" and Ahtanum Rd. IS - 20 Develop a Coordinated Resource Management Group L L NYCD/WDFW to develop joint priorities for resource management (e.g. Wenas working group). IS - 21 Investigate and recommend increased maintenance L L Roads and debris cleanout of culverts and ditches on public roads (coordinate with road maintenance crews to optimize ditch cleaning for flood purposes) IS - 22 Monitor effects of urbanization and land use L L FCZD intensifications to the characteristics (runoff, time of concentration, water quality) of the watershed over time. Take action to mitigate for negative watershed scale effects. IS - 23 Map non — mapped Channel Migration Zones (and 0 L FCZD/ plan Depts other hazards) (15G -4, 15D -3). Identify areas that are at risk for channel migration in addition to identified CMZ, i.e. N.F. Ahtanum, below the Narrows, at the Mission, Shaw Creek, etc. IS - 24 Alter drainage systems and easements, based on 0 L FCZD Emma Lane floodplain remap study. IS - 25 Inventory of private roads acting as levees. 0 L FCZD IS - 26 Private road culvert inventory. 0 L FCZD I5 Investigate funding sources or incentives for private 0 L FCZD drainage infrastructure. X I Ahtanum -Wide Hollow Draft CFHMP ES -3 Recommendations for Flood Hazard Mitigation PLANNING & REGULATORY Policy Development To be implemented in the policy processes associated with the broad scale Growth Management Act processes such as County -Wide Planning Policies, Comprehensive Plans, Capital Facilities Plan Elements, and UGA expansion. Description Onset Priority Partners PR - Ensure drainage infrastructure is properly sited, sized IP H RSPG /Stormwater and designed to minimize flood effects from stormwater Utilities run -off. This includes establishing the relationship between flooding and stormwater and determining detention /retention and other stormwater standards. PR - Petition State Noxious Weed Control Board to list IP H FCZD hybrid willows as invasive species as designated in other states. PR - Incorporate floodplain and economic impacts into S H Plan Depts /FCZD SEPA for subdivision layouts floodplain development (losses, damages, safety, insurance, response and recovery) from the planning to the project level, especially in urban and urbanizing areas. PR - Establish policies, such as a flood hazard audit and AU H Plan Depts/FCZD hazard element using the flood problem inventory in this plan, within County -wide planning policies and comprehensive plans in flood hazard areas to direct preferred locations for new infrastructure such as arterials, water and wastewater distribution mainlines, regional stormwater facilities, parks and greenbelts. o New major arterials should be located outside of floodplains where possible. If in floodplain, design to minimize flood impacts. PR - Retain and provide Open Space land use in all AU H Plan Depts/ FCZD jurisdictions using zoning easements, acquisitions and incentives within floodplains to provide multiple public benefits such as preserving space for flooding, greenbelts and trails. PR - Provide open space incentives that target general AU H Jurisdictions /Plan floodplain function, riparian and storage recommendations. Depts., Interest Groups, FCZD PR - Decide upon, designate (in flood response, S H Roads/YVOEM transportation and capital facilities plans) and maintain critical access routes at 10, 25 and 100 year events. PR - 19 Develop flood abatement policies for high risk flood 0 M Plan Depts/ FCZD prone areas of existing dense development in the floodplain. o Design drainage to meet multiple objectives FCZD/Plan including flood alleviation, in flood -prone areas, esp. Depts in Wiley City and Ahtanum. L PR - 20 Identify areas that are "islands" surrounded by L M FCZD /Plan floodplain and develop standards to limit density, provide Depts emergency access and consider transportation networks within the context of surrounding area. PR - 21 Seek land use examples for flood -prone areas from L M FCZD /Plan other similar communities. Depts EXECUTIVE SUMMARY I XI PLANNING & REGULATORY (cont) Description Onset Priority Partners PR - 24 Preserve natural drainage including draws and S M Plan Depts mitigate identified hollows that provide natural flood flow paths but are not identified as FEMA floodplains. Implementation is through drainage requirements within stormwater, County /City drainage, grading, and long and short subdivision ordinances. PR - 25 Consider development moratoriums or high 0 M Plan Depts standards of proof in place where development is outpacing flood knowledge or tools available to keep the public safe (i.e. the area has not been mapped, or conditions have changed since the last mapping). PR - 26 Maintain open areas near the mouth of Ahtanum 0 M Plan Depts Creek for flooding such as Fulbright Park. PR - 30 Take larger scale effects to the watershed into account AU L Roads / Plan Depts when designing new transportation systems: Minimize number of roads — maximize efficiency and design roads in a manner to minimize flooding. PR - 31 Assess the cumulative effect of road policies and AU L Roads /Plan Depts standards for new roads within the transportation element of the comprehensive plan that act as dams or conveyances. PR - 32 Limit future development in the Emma Lane AU L Plan Depts floodplain area if structural alternatives not implemented. PR - 33 Place controls on building in the flood -prone areas in AU L County Plan Dept and around Emma Lane (e.g. using zoning, utility hook -ups, etc.) PR - 34 Investigate geologic hazard area standards for L L FCZD/ Plan Depts, Bldg applicability to high flood risk hazard categories such as Officials channel migration zones and alluvial fans to address potential regulatory gaps. Standards and Ordinance Development - To be implemented in association with the development and approval processes for ordinances that implement the Comprehensive Plan, and in some cases modifications to the building codes. Some of these recommendations (work group) would need to begin well before modifications to existing ordinances are proposed. PR - Ensure all new development and redevelopment AU H Plans Depts/ within identified FEMA floodplains are adequately FCZD reviewed for NFIP compliance and overall environmental (SEPA) impacts through the use of additional review procedures which may include; at minimum a public notice (type 2 for the County), a signed checklist for all floodplain items; a floodplain development permit independent of other required permits; or establishing a floodplain overlay zone covering the above concerns. PR - Establish work groups to formalize regulatory S H Plans Depts/ applicability of man -made and natural courses. FCZD PR - 10 Ordinance increase for residential to at least one foot AU H Bldg Officials/ Plan Depts above BFE for future development to reduce community costs and damage. PR - 27 Work for consistency in zoning and development AU M Plan Depts standards across jurisdictions for developments and buildings within floodplains. Determine gaps in the regulatory scheme. XII Ahtanum -Wide Hollow Draft CFHMP PLANNING & REGULATORY (cont) Standards and Ordinance Development - To be implemented in association with the development and approval processes for ordinances that implement the Comprehensive Plan, and in some cases modifications to the building codes. Some of these recommendations (work group) would need to begin well before modifications to existing ordinances are proposed. Description Onset Priority Partners PR - 28 Reduce risks through subdivision development M standards to minimize new structures in harm's way o Integrate protection of floodplain functions improvement /flood hazard reduction into 0 Plan Depts subdivision platting process. o At a minimum, require a buildable area outside of the floodplain including standards for lot size and 0 Plan Depts housing location. PR - 29 This includes special land use standards for industrial SU M Plan Depts/ uses relating to hazardous materials, storage, use, disposal Bldg Officials and flood - proofing for non - residential structures, including elevating to make existing structures less flood damage prone. Jurisdictions should adopt Appendix G of IBC. PR - 35 Adopt and implement stricter building standards in AU L County Plan & Emma Lane area - flood - proofed homes, buildings. Bldg Officials PR - 36 New traffic generating developments should be 0 L Jurisdictions, Plan & located outside of floodplains (see also Bridges & Roads). FCZD Project and Permit Level — These recommendations should be incorporated as standards of review for development in floodplains, mostly in relation to new subdivisions, commercial /industrial and public and private infrastructure projects. PR - 11 Improve compliance with NFIP on all new and IP H Bldg Officials replacement bridges and culverts. PR - 12 Based on the 10 and 25 -year flood mapping, consider S H Plan Depts/WDFW them, for design requirement of land use designation decisions in future floodplain development to minimize frequent damages and economic impact. PR - 13 Use SEPA and Comprehensive Plan Policies and S H Plan Depts Goals to address flood issues /impacts associated with larger scale proposed developments where current zoning, subdivision or building standards are not sufficient to mitigate flood risk. PR - 14 Implement NPDES Regional stormwater to limit run- IP H Local Jurisdictions off up to 100 -yr flood. PR - 15 Fully utilize new FEMA models and maps, and S H Plan Depts/ locally developed 10 and 25 -yr map products, including loss Roads data, for alternative analysis and infrastructure and land use decision making, by providing models and mapping free of charge. PR - 16 Consolidate access for floodplain crossing to AU H Plan Depts/ minimize flood impacts. Roads EXECUTIVE SUMMARY I XIII PLANNING & REGULATORY (cont) Standards and Ordinance Development - To be implemented in association with the development and approval processes for ordinances that implement the Comprehensive Plan, and in some cases modifications to the building codes. Some of these recommendations (work group) would need to begin well before modifications to existing ordinances are proposed. Description Onset Priority Partners PR - 17 Ensure floodplains and floodways are identified on AU H Plan Depts final plat maps — included would be text identifying effective map date and disclosure regarding fact that the maps will change over time. Also consider including identification of riverine Critical Areas buffer on plats. PR - 18 Increase flood code enforcement through adequate S H Code funding mechanisms 6.3.A. Enforcement PR - 37 Improve drainage throughout the entire Emma Lane IP L Roads area — culverts, roads, etc. MAINTENANCE & MANAGEMENT Continuous and stable Channel and Riparian Management MM - Program for sediment and debris removal, invasive IP H WDFW/FCZD Plan species control, replacement species in plantings, sediment Depts, & bank stabilization. NYCD MM - Beaver management. IP H WDFW/Landowners MM - Riverine Infrastructure Management — debris and IP H Jurisdictions/ sediment maintenance. Irrigators MM - Riparian restoration, mitigation and protection to S H FCZD/WDFW reduce flood impacts. Jurisdictions MM - Land acquisition in problem areas prior to IP H FCZD/ Jurisdictions development (Emma Lane /Cottonwood /Shaw Creek/Union Landowners/ Interest Gap, etc.). groups, MM - Apply appropriate range management standards to S H WDFW elk in confined feeding operations near riverine environment. MM - Obtain landowner access permission for problem IP H FCZD/ Jurisdictions bridge channel maintenance. MM - Coordinate opening irrigation diversion gates for IP H FCZD/Irrigators YVOEM flood relief, based on forecasts, channel maintenance needs, and impact to diversion facility. MM - Separate irrigation conveyances from streams as L H Irrigators/ Jurisdictions practical and based on priority MM -10 Consolidate irrigation diversions and remove as L H BOR/BPA/ become obsolete. Irrigators, Jurisdictions MM -11 Community adoption of Community Rating System L H Jurisdictions to reduce insurance rates through CRS activities. MM - 12 Investigate irrigation infrastructure changes such as L M Irrigators flood gates or siphons to reduce flood routing through irrigation systems. MM - 13 Modify drainage standards for existing roads in AU M Roads/FCZD overflow areas to minimize flood impacts (i.e. Emma Lane area). MM - 14 Ensure replacement of damaged infrastructure 0 M Roads reduces future flood damage risks. MM - 15 Explore additional funding methods for mitigation 0 M Roads or reduce environmental effects (including flooding) from existing roads or other infrastructure. XIV I Ahtanum -Wide Hollow Draft CFHMP MAINTENANCE & MANAGEMENT (cont) Continuous and stable Channel and Riparian Management Description Onset Priority Partners MM - 16 The Spring Creek floodgate should generally be IP L Union Gap/FCZD closed except for habitat or flow enhancement for a limited time period (see alternative F below also). MM - 17 Review DID management in relation to flood hazard L L DIDs (County) over the long term as land use changes. MM - 18 Investigate funding for enforcement and cleanup of 0 L SW, DOE & illegal dumps on private ground. Health Dist MM - 19 Improve stormwater system on Ahtanum Road to 0 L City of Yakima limit Emma Lane overflows into the airport area, and downstream to 16th (which floods the intersection at Ahtanum Road). MM - 20 Investigate methods for the following: 0 L SW, FCZD, Jurisdictions - Research how other communities deal with dumping in floodplains, particularly concrete, fill, etc. - Research measures to deal with illegal /contaminated dumps (meth labs, etc.) - Examine statewide laws relating to dumping and streams to establish authorities. MM - 21 Utilize fence designs that prevent floodwaters from 0 L NYCD/FCZD Bldg backing up on fences, such as: Officials, Plan Depts o Breakaway fence panels in locations that flood frequently. o Suspension fences, which consist of steel pipe or cable hung high above the creek, and hanging lighter materials down from the cable. This works as a fence, but is not lost during floods. Fence setbacks — hold fences back some distance from the creek (loss of traditional land usage). STRUCTURAL Projects in Urban Growth Areas ST - Property acquisitions and home elevations for IP H FCZD/ repetitive loss properties. Jurisdictions ST - Emma Lane channel improvements. IP H FCZD/ Jurisdictions ST - Bachelor Bridge at Ahtanum Rd. & Ahtanum Creek & 0 H County Roads/ Plan Depts 16th Avenue bridge replacements ST - Wide Hollow flooding between 64th and 101st— channel IP H FCZD/ improvements and acquisitions — recommendations include Jurisdictions those for Shaw Creek, plus regional retention ST - Resolve Shaw Creek relocation /overflow to remove S H FCZD/ Jurisdictions, Plan community damages and insurance Depts. ST - Wide Hollow relocation or overflow channel 0 H DOT/ incorporated in future development and proposed Jurisdictions infrastructure design in Union Gap ST - Improve grade for Spring Creek East to reduce 0 H DOT/ flooding in Union Gap Jurisdictions ST - Mill structure — Develop shelf ready open channel 0 H FCZD/ bypass design for grant application on, lower channel Jurisdictions EXECUTIVE SUMMARY I XV STRUCTURAL (cont) Projects in City of Union Gap Description 'Onset 'Priority Partners Projects in areas which route floodwaters overland ST - Reduce catastrophic flow captures at Mission S H FCD/Irrigators (infrastructure and town impacts — Rutherford Road) and landowners, Plan Depts preventing avulsions into Hatton and capacity issues ST - 10 Flood design for John Cox diversion (new) L H FCZD/Irrigators ST - 11 Make infrastructure improvements in Emma Lane M area: IP FCZD/ o Remove abandoned fill and infrastructure in Emma Landowners Lane area to increase flood capacity and reduce redirection of flood flows o Widen bridge at 42" Ave. IP Roads ST - 12 Evaluate not filling in the existing Ahtanum channel IP M FCZD/ so it can be used for habitat if the creek is relocated near Landowners Emma Lane ST - 13 Perform a cost - benefit analysis for stream relocation IP M FCZD near Emma Lane ST - 14 Improve flood conveyance and predictability by L M FCZD reconfiguring modified or "perched" streams and establishing overflow channels if relocation is not feasible such as Shaw, and Emma Lane ST - 15 Maintain Wide Hollow flood mitigation methods in 0 M City of Union Union Gap by retaining an overflow path along railroad Gap right of way and encouraging development of an 0 & M agreement among appropriate parties for flood and fish structures the Mill ST - 16 Consider the following structural alternatives where L L FCZD/ Plan Depts changes in the channel threaten homes, businesses, agricultural land, or infrastructure. o Levees, armor, buffers, CMZ (channel migration zones) o Structural flood control measures either by individuals or government o Utilize "softer" solutions for bank stabilization, bio- engineering. o Levees constructed along perched channels (i.e. Cottonwood Grove) ST - 17 Expand diking along Shaw Creek to protect new and L L Add Insurance existing development Costs ST - 18 In some locations, add wood to stream to "catch" 0 L FCZD wood debris — this accomplishes multiple objectives — would benefit habitat as well as reduce the volume of woody debris that accumulates on bridges, diversions, and other structures. ST - 19 Armoring: 0 L FCZD - Provide armoring of roads with act as levees (Ahtanum /Cottonwood Canyon Rd., etc.). - Armor road ditches where road fill is going to contribute to excess bedload and to protect road prism. XVI I Ahtanum -Wide Hollow Draft CFHMP STRUCTURAL (cont) Projects in City of Union Gap Description Onset Priority Partners ST - 20 Culverts: 0 L FCZD & Jurisdictions - Recognize the limitations of culverts as flood Roads conveyance structures - Replace old culverts with higher capacity culverts based on flood risk ST - 21 Identify sources of funding for removal of abandoned 0 L FCZD & Agencies irrigation structures ST - 22 Preserve and restore natural floodplain in places that 0 L FCZD retain some of the floodplain function. Prioritization - allow for flexibility while identifying critical locations, based on CFHMP and mapping. - ST - 23 Install a remote control floodgate that could be 0 L City of UG opened some times of year, closed at others (on Spring Creek floodgate) ST - 24 Protect natural floodplain functions in Shaw Creek's 0 L FCZD watershed, especially before it is mapped. • PUBLIC OUTREACH P0 Information to public and local governments on New IP H FCZD/ FEMA Maps Jurisdictions P0 Outreach to public regarding flood hazard related to IP H FCZD/ plan Depts regulatory changes P0 Provide flood risk & regulatory constraints at S H Plan Depts beginning of development process P0 Outreach to Realtors, lenders, etc. about flood risks S H FCZD P0 Provide information to the general public and L H FCZD/Plan property owners to enhance their understanding of: specific Depts flood risks, beneficial functions of floodplain, and aesthetic values of streams and floodplains for development P0 Work with landowner assistance programs to improve S M FCZD appropriate streamside vegetation and provide information about flood resistant fencing P0 Utilize meetings and other methods of notification to IP M FCZD inform developers and current and prospective residents about flood risks for Shaw Creek P0 Encourage residents and property owners who are at IP M Jurisdictions high risk for flooding to purchase flood insurance even if they are not in a mapped floodplain P0 Provide public notice /disclosure /consultation about 0 M Jurisdictions/ planned flood projects FCZD P0 Provide information for the public about culvert S M FCZD/Roads maintenance and sizing P0 Yakima County Flood Control Zone District to IP M FCZD provide technical assistance and comments regarding flood hazards and infrastructure design P0 Encourage volunteer flood - watchers program to S M FCZD provide information P0 Cooperate with other agencies to support or develop IP L FCZD public education programs, such as stream cleanup programs and volunteer monitoring. P0 Encourage citizens to report dumping in streams L L FCZD (public outreach). EXECUTIVE SUMMARY I XVII FLOOD RESPONSE Description Onset Priority Partners FR -1 Designation of evacuation routes and notification of S H YVOEM /Roads the public and first responders FR -2 Implement and participate in activities for the Flood S H YVOEM/ Response Plan Jurisdictions FR -3 EOC environmental coordination L H EOC/WDFW FR -4 Determine where large numbers of animals may be L H Conservation kept during a flood event and distribute information to the Authorities public. Work with Emergency Management and Red Cross to establish animal food and shelter contingencies — discussions may include Central Washington State Fairgrounds, farm feed stores, FR -5 Coordination between Emergency Management and 0 H YVOEM /AID the Irrigation Districts such as AID and Yakima Valley YVCCo Canal, for management during floods. Include Irrigation Districts in communications with the EOC FR -6 Public and agencies coordinate flood fight and post S M YVOEM flood actions with recommendations identified in the Ahtanum -Wide Hollow CFHMP to provide a good basis for decision whether to take emergency action FR -7 Install gages on North Fork Ahtanum and Wide 0 M FCZD Hollow Creeks, including telemetry FR-8 Develop warning systems including mass media L M YVOEM FR -9 Identify known problem locations so information is S M YVOEM/ FCZD available for first responders and include in the Flood Response Plan (if appropriate) FR -10 Provide special flood phone line for public to call in L M YVOEM/ FCZD and provide information about current flooding — EOC & FCZD cooperate /coordinate FR -11 Improve access to Bachelor diversion during floods L M Irrigators/ BOR without diverting flood waters or making flood problems worse FR -12 Improve communication, coordination and IP M YVOEM information dissemination between various agencies and emergency management office during flood emergencies FR -13 Coordinate between jurisdiction procedures in place 0 L OEM, Jurisdictions, for expedited permit issuance during and period after a Agencies, FCZD flood event under State and County regulations. FR -14 Outline emergency response to ice jams in the Flood 0 L FCZD /Agencies Response Plan. - Alert residences at risk. (new) - Blast ice jams — (normally only done on very stable ice jams) Facilitate regulatory approval by Ecology and Fish & Wildlife and local jurisdictions due to short time frame. (new) XVIII I Ahtanum -Wide Hollow Draft CFHMP Mapping Tools The recently released (2011) Preliminary FIS maps for the 100 year flood increase awareness of flood hazard. From the extent and nature of the flooding portrayed on the FEMA maps it is evident that, despite the implementation of this plan, infrequent flood events such as the 100 year event will continue to affect large areas, causing substantial damage and economic disruption. Frequent floods, from a five year interval up to the 25 year flood, produce the majority of property damage and economic disruption to the community over time. As part of this plan, 10 and 25 year flood maps are provided that can serve as guidelines for future infrastructure planning. Preferred Implementation Order for Recommendation Categories The Inventory and Study recommendation category should be implemented first as the topics they cover increase awareness of flooding problems, problem causes and locations, and may amend other recommendations. In particular the high priority recommendations have been pursued by the FCZD to facilitate other recommendations. The inventory results may change the focus of, or add to, some of the Planning and Regulatory, Maintenance, and Structural recommendations, so that maximum public benefit can be attained at reduced costs. Several of these inventories, including problem bridges, and the effects of Drainage Improvement District facilities (DIDs) will improve management of floods and allow tracking of changes to the basin into the future. Recommendations to minimize future damages for new development require Planning and Regulatory recommendations due to the widespread flooding nature (generally shallow) of major floods (i.e., in the order of the 100 year), the general inability of structural measures to remove such large affected areas from flooding, the relative effect of minor changes to the landscape (fences, roads, emergency flood berms) on flood routing and potential flood damage, and the impracticality of halting development or re- development on large tracts of land. For existing development floods between the 10 and 25 -year return period frequency will cause the majority of long term property damage and economic disruption to the community. For these floods, which are more frequent than the 100 -year flood, which generally occur in the areas adjacent to stream and river channels, versus the overflow paths, the Maintenance and Management plus the Structural recommendations will provide the highest return. The plan has developed and provided flood maps for 10 and 25 year flood levels in Appendix J and sediment removal guidelines in appendix G to enable the communities to guide these recommendations. Reducing future and current damages across the range of flood events will require a combination of modified design guidelines and standards, land use zoning, related planning methods, flood response and channel maintenance. Cornerstone to these mitigation recommendations is community involvement and a cooperative approach involving agencies and the public. Recommendations for this element are contained in the Public Outreach. EXECUTIVE SUMMARY I XIX Implementation Strategy The purpose of a CFHMP is to propose a suite of actions that will reduce flood hazards over both the short and long term. In order to develop a long term strategy it was necessary to understand the underlying causes and obstacles to overcome. The most relevant new understanding attained during development of this plan, apart from the large extent of flooding, was the pervasive and historic nature of floodplain and channel modifications to suit agricultural practices and the legacy that alteration presents for future urbanization of the floodplains. The greatest return on investment is to increase flood hazard awareness. Public Outreach recommendations, including distribution of this Plan, will extend the awareness of past and future floodplain changes. Development of the Plan increased awareness of information needs to fill data gaps, therefore, the Inventory recommendations received the highest implementation priority. Answering what and why certain actions will be effective are the critical components of an implementation strategy for the plan. The answers to these questions differ for new and existing development. For new development, a higher priority is placed on Planning and Regulatory recommendations. For existing development, a significant specific issue is channel sediment and invasive vegetation, and the need for a maintenance program to manage their effects. Studies to quantify the impacts of sediment at bridges and in the channels have been initiated as a result of this Plan (Appendix G) so that Maintenance recommendations can be more effective. Recommendations for structural alternatives primarily act to route more water into the main channels and transfer flow capacity issues from one location to another, where channel capacity should be higher and impacts less. Many of the recommended structural projects are located in the Urban Growth Areas and should be implemented sooner rather than later — before development precludes the opportunity for these structural alternatives and flood hazard conditions are fixed in place. Some of the structural recommendations in the plan address critical locations in these watersheds where overflow paths for large floods originate. These overflow points are usually activated during frequent floods. Once identified, the projects focus on these locations to reduce the frequent chronic, wide spread flooding. Other structural recommendations are located in already urbanized areas, and will be implemented in conjunction with planned infrastructure or redevelopment activities as the opportunity arises. The most economic action after the provision of selected Inventory recommendations is to translate the new awareness into design and planning guidelines and building restrictions that mitigate flood effects. Jurisdiction planning measures should acknowledge the legacy of agricultural conversion of floodplains to more flood -prone development. Building code revisions that reduce future economic burden to the citizens through flood insurance reduction should be pursued to avoid subsidizing other more flood prone communities. XX I Ahtanum -Wide Hollow Draft CFHMP The next most economical action is to address existing flood issues specific to a cause through wider actions such as channel maintenance. The most expensive category is to address existing flood issues specific to a location. Structural projects are typically very expensive; however, projects should be addressed as soon as practical before the land is overdeveloped or under urbanization development pressures. Structural projects, such as levees, also require maintenance that is a continual commitment of resources, making them the least financially attractive. In most cases the structural measures are more suited to 10 and 25—yr floods as they encompass the majority of the community losses, as determined through economic analysis. A Funding Strategy is presented in Chapter 12. Distribute Meeting iIt )' [a AHTANUM -WIDE HOLLOW i9 � COMPREHENSIVE FLOOD HAZARD MANAGEMENT PLAN Rutherford Road it v. October 2011 .v - i , ....,.'. ', 1 • 1., . , : ..11" . _ , - -".". - . Rutherford Road i 1974 Flood _ • __ .. r-- r y I ti - I -F 1 • k. � y ' ...• 1996 Flood i "air • - Y 4 • /� t,T • SERVICE • B Z. : �, g ;\k , , cI i neon Gap - . ,� ..r. , . 10 1 Ahtanum-_ Draft CFHMP Figure 7-2 1996 Ahtanum Floodin_ • g Emma Lane & 42nd - looking Southeast . ... --.- -,...- --- •,......... - , _.•-- .41misows■-• ,1 -- - IN * MO ., ...4•00040 1111111ffirr-'glie -- _ ": _ - 1 : _ , ■1 .... .. tr" ."' 0 • . .. ' 4111111■ -. • - ._ _ _ ""-, : .. ,....- -AVA _ ilblimn - _ . • _ 4,- .• -__ - - 71 11POIPW - . _ • . -• • . ...• ......, - ....iii - - 1■1,,,, m ,„,„„,_ .0 . • dr , • .. al " a _ t _ __ -..... _ i r .. ., ... ---.; . - • .. .- - "glilk ...-laillailliV Rutherford Road - looking Northeast . .- AllPill ' ilPiliaF _,...,...4111.11111M 4.111111 e‘11184-4- Al ....1111.1.1 ...• -..■• mint ■■ • ■ . S . P IIIIIPII . 1.11111rb '. ---.V. , . ........1000. 110 1111191111411W it & '" • -,, ---".- Z • AlliNc `,. ,. -...a - ......- - 111 • - • * -4... doe ...- „--:•5. . . :,,.. .... - , ■I . ... • - - ...,,- , ---!- - . . ... , .... ' A - *411. y ill 111110"..-- O 4111101 -4 . ., - . - dlii 4. .... . .. e 41 . .. Chapter 7 - Basin Flooding Characteristics 111 Figure 7 -3 1996 Ahtanum Flooding Community of Ahtanum- l_ ooking East 7-1-42:5r--- ''...."1 "-°1111.';--.--.."11111111111 1 '� +f'•. - -e +� ! " � �- _ ..\• If IP ' ,,,.: ..--44:NN Nib. Ike 7:;1 :.0 mo t. ..a i Wiley City - looking North - _.-- - — _lmea. x-,- -' T 7 - — . — . ,. _ • iiiiii all. `fir V ' y ! 9 FEES T ' _ -. :9h AIR _.... 41111111W Results - Sri. ` 11 _ >,,,,:_ . ,+ } •S n + ' r• } �. ` , t • ! 7.1 % j . ``,� ° `. ij 1..� .4 . .rh '111 f '4' •'4 ..+s' - _. ---,', • .. N ., yy 4, - - *140porr . - ' s yam' i1 • . T `- - 4. 4. p . - .‘ i 4 i • 7 7 - '11'‘ , 1, .... trip , I t . N 7 - 4C .: 1$11* ,..t01/1 i iki .., t & il , Ali., , - .,...,c77... di , ' ---1.-..x 7,64sc- - , , -... / l ir . 4Nrit . Illr _...., ,r ,,,,,.. -, . , 4..t.„, op* - . , r e , M i i .. .. ,147.i.., ` _ 1.• _ -. � i y ' r� F r 1 • __ . II yi • r .. * �a 1 '.. i/ — Cill of 'Yakima .. 1 T f � - FMw �I.Ppi., Camprfwn IL 114111 \, 7''F -. Flow Map ' > • Jh < A i'''''!+ : i :: y . .l. T � .r ' - Kbw „f ..e . L P , a Li 7-0 . ,..i ' { 4 "r,. I Y+ x o z r . • M IUN IIUIIUN/NNF.IA ,, r ill' I.: + j K , . f r Y N d k � _ -••' Y[ _ � L! J t1' rl: . 4.'4 1.",=,,,%.,: , a ♦ � ti 6 1 . r * r , , . rt' / h ' ,ti . crit I - e 'y]• F a 1 " 4 - rw�w • y iV ',�'f ' p e� , " , f " , T TM , 1 - 1 • �, I t 5o. ri r +ry &L+. s . y J j . . ,,H,f �� Y 6 , �, �� _ r. 51 ?li '.. �. . }15 d �'f. ', _ r .G ' a10'- ` T'° r1• C ti .; J AHT\1 M.NA(HNIIIN . ~ ... „_ • lt._1 tx � 7 y •.. '�° ' ' 'A `�'' '- r .a- -M. Y'+$ I�t�.lt � %:ice �! it ��. �'R'. r f �IU� r .r H�rro.rII II } x �' y ,w .. - 1 it How V .P • • ✓.r•- a . *. t iv I ' a r f'GR�'.. ,- 1 r -�: i -i .. y - , ' N �� �� ' r • i : �� CI of Yakima I ^ ~ t , p E VIr.e.., l ' ` � _ � 1 ' 1 ip, , ' ' 4 ok 5 , — .- � �;. t 1 `` , i , , _ .. Q'e . 1 1 t 1 ,, 'a ` �:t - 2 ,c - rn.. wr,�rK -, :ice .. r ' T `• ..,. - A. � ! 'g� r ' • r taa• �! ,. y 0 / y 1 F .., l'3 } r . r24� i . ! r rrrrwr� ,,i r —. . N r /- '�', .. ice ;*, �G�� f.� ,� 0-e, .. , . - - _ wr/arr>'sni.,o y 1 7 ' • `" A . ` e ... , K., �9 ./5� a ` '`ryr�f.` - r mo t _ X f ~ 1---#_9,-,.# � + � �. s `�`'� + � w. j ' i ,tra ,� ,.'0•. - 0.•'t.' g 5 � i TTT r Cal;01 - ... r if 7I 1` - , b ?� I •�� �i ! 1 `.ir -r ■ yy ~ f r •r.; .. ..- 4t,, . 1 ywi1L_ as_ y k r `r •. 1 ",i' c),.. ti r lK ` �. ,.r_ "' ` � ':.� ' a '' I11 T r` ::r � 7f 7:1:'''0"/"'" . i L it ?' ,M' ... . 4 11.4k: - r- ` ! ` Dr ; 1 P. . - —9 , ] , ` , ,. , r ir< - . ' ' z / / r .�t ., f` 4. _ k l L '' y> f r ` x -,-,..,2 i ' _. . ' 1.. . ° f -4 ' . - --, /i!' �,, ter(, � , ,,,,1, i `: - y + , : `. . -. :°� , & ' . f xAo 1 � ` �� i ` Bachelor Creek 41 _,r /':;! ��— _ 1' ' r fir.,. ! r i � r _ / i ' • • _,J lat 1. F � ., / 4 .dI 4.. J ' '' •• r. . ��,. v ! • t f V i "AV 4 ± �� f .,. . — Y,r - • .„4A. a� • • /,•, f f " /� . -'� i , - , w ' ' iT. r .,'_ �ir!;: r� �. , ., �' • r a ns Cree +. �,.� I K. s, ' r * 'y . / •� ®:r- I '► "'r �'' A bt ^u `r1r " _ �' .!�_l_ �1y L — II Mirjr , I � �� .' `' n:- � '4" s , v�.; . .. i i . A l > r Zv i . r � a • Study Area i ,_r- R \l,k‘. t r 1 ✓ _ i � i ��r,.♦ co..h :. - w r 1 w 4�� i .., , ,, � ;r 0 ' Ahtanum -wde Hollow CFHMP • I ' , - % �, -� / , � =�1/ � � , ,/ , e ' - ' • / i • - r C ity LimAs �Lw, • . �- �, . / sf . � . a , 1 I J I. Study Area Boundary r ` _ � ` ' _ ` � P/ _ _ _ - _� ` F - _� ` \+ ' \ � \ • - -' i t ' r' y., � ` ' • �` i ` �� , i 1 • / „40 or" +) , ' I '' °p4,1, 1:'41 � - ` ■ V i - - • / ...i 5 ‘ ,. \ r. _ • '\ Rte' - ' - - - , ' =y;;;` Ally • .. , \ "...% Mille Llo�low ate $ Yakima 'll� i % % kt ‘• ' '..'... '' - ... '' ....':'s . . 411 . , . . ... 7. _ ... _.„...--, & le . - ..... - ../ yam- •I - s ; 1 \--``-* __, - , _ ` ` Q ` `` \1 \ , \ A r46,* `._- J _ ,,'� - Nom"• r �r,<.•+1 J • r --j a , / ` / -- - r , " : _ _ - - . , . .1 iihne /Z -- ).- - - N- z z , .1rop wr - 4, ...„....„.,. iyis r • i... 1 1 Comprehensive Flood Hazard Management Plan (CFHMP) Process Establish Community Participation 1 ■ Establish CFHMP Advisory Committee V Inventory Physical Conditions & Public W orkshops i Set Goals & Objectives V a) Determine the need for .v flood hazard management measures v Identify alternate flood hazard management alternatives - structural & non - structural -a Review concurrent N FEMA restudy flood maps Evaluate alternative measures with respect to goals & objectives, cost, benefits & impacts 1 Develop a flood hazard management strategy 1 ► Complete draft plan Plan reviewed by local jurisdictions 1 Local SEPA review & approval Submit final plan to local jurisdictions for public hearing & adoption 4. Submit plan to Ecology '.ir:- ' . ,,- . ,.. . .1. , URBAN GROWTH • - 1970 City Limits I I 100 Yr Floodplain i I N _ . : ... • _, . -J rir_ .17-411117111111 _ - 2011 City Limits ...... 10' Contours INNIMINIIIIMEM iN 17. .., F ...-tE un qr i -.,„,' •1111 - • . N. r" I , .. s• 2011 Urban Growth Area .•■■•••• s q it z - . JElloriparaw .: 1 "-r). M., ,..-,,. a PI, ,7•,..., :y. ' .14: ' '•-•• ,. ',1 4 11- - -:.:‘,...71.÷."7■ .." ', _..:?, 3so - ,:i.T.1: - - ..j,4 = ... • 4 . '.- A. 1:11Efial ..411111111111111 ''411, .'. - : Y - . ('‘';'..7• --1V1L-,`-'- ;: tt*,..- - --- - -itr l '?"!- I rj. r ' , ' . -'• , ,- -`.., 0 ; • " Ira 11).1 illif I. NE I M , 11 10 .i ll ' I . Irrli• t: ■, ,ai OF '.. ' '2 ' '' ' ‘1 4 . i: --._ .....- 4 14Irl -' •7:. ";:l•s , l' . . ' ..a - - , vim— iirimontaninum tolido.* • ,_,, ...1 .. f-, _..• ;1,, ----.-, - - ,-,:_-__.:,,,, .. . ., _-- ..,-_. ,-- :, pi., : . - ---: ip. -- m 001,4 'ea. ., . Mk ,..., 0.• . .. . ... - '''' .." ' ‘. ''' °. ' - : . -- --7-'- - ''' '' - - V 47 --"-- ' - , - m'i :...7:• , LIININN /LA 00 0 .1110011.1.w.■ ,-..-: ' % ... '"' ''''' • ' • • -- - • . 4 - - - -- ' I.:- ' . :WI ii All i:■•:'_''.':! .',.0:.;N.:, Vita :1,4=.1 All 41,01*Vii IA,. 144 'Ft il ill! :."-. . ' --- - - : , - - ' ‘ - • - - - — _. - _----_-- -, - -410,..e#b : ..-..,i- -- vi EN 31.ar, --. N. Is o - lip -400010- 31.1 -- , . - -, , --:_ , , ,,-- - - - ..,,-;;;:--,:: :- ..,: . _.„.- m s. , ,; , -1 7. „Iiil. la 1111.4:1MMM I .-.11 1,12 .01 iik . , ■., • '.111:•ti..7 •M , '• ',,- - ft., t■.:.,, , ,,, , 1 ,i, • :!!',.: ',....:- ,,,,401%1/a Iii■., ./..7 .;‘,./ -,.t. gr wir tills u ....i 0,110,11111.0%. 067.64:4*,.• Timm , -,-_, . - . ,,. ,,, .-.- -_,...- _ ..--- 4 ,.... ..., ,...•.,-, 4 1.1001 a •••.10101•1. * -_, . ' ' 4, ' -'. '',. :,,, : -..,_-_ -.4 4-„,,; owls o i i bit :.--'''' )1.. 0100 ISI Ir i lfrirk - ,. -- . ': •. :, - i.i '- c, • .1.. " - - -, - - ... 4 . : _.4,. ..,,, _ +, _„.„ - .„%,. _. ,..._, ....-2■ 0- 4,00' L. - r, -- - - .■,„t111,1,1I.11::;,;-,.; ■ 7 1 ,001 ON .4111. 1,1■ or` ' il • " ' ' ' ' n ' ■ - - - - - - - " - -- . - "." - '-- -' -. - \ ...7:, iii,4?--rie..,,, z.--...,.-11:. livae,:,:,,: ... 4 .7„-„•• - i■ 1. ,... i',.. . - • ---' - - •' - ."! - 7 . - -- •: - ''''', .• 7' , ,;;;;-- ' - ua. -L,..ii I, W -,- -- —. .i - .119 - ' ' ''''''•• Aw' .....'" ' 1/4. .4 — - 'I - - IrL '' w' 11111. ' - . . I t ''''' — ' . = ..; ' ;'- ; ' ' ''' . 77- - --- - ... 4;4 ' ° f' . ;.'"n - - ... ' 4'-' s • I 1 PIW44:1 1" ., ' ‘ ON;ZILI:4 • 7 1p1..' '40010 111 Otrin I 'A, , 14 - , -- "1:-:;4 1. "■ - :- - - ' ' -- ' %V. •-• - f . .--- ‘--- - .4i t 'd ,P ri" - ' ' - '-... ..-- - - -:,■•• i• -- . ii,,,,,„,-.......!-,-,- , ,, rf , i , i ir:-?:1.7..........„.......:-..::,:...., .-_--, . ,.• .., - l ot. 0,111k solo* ,,s. ortikinii, i . , __. A ,:,„__ .L;41,0 re, „, ,,-.■ r,rz2b .., ,,, ....wok NIL -.: . • .-:!:... . : 11 . - _ lob ■17,• — ;' s r 0,0 to , =mow ,I ._ ir - -- ---- '-- , i-s-- --------, . -...vAlar• „6 - i.e.: .,' .<- (.1 ft. ! lt..it-t. All sgivi.....10.--101,■,.,., it , ___-_,.., ...I 7 :... ' .(0,1•i•EIL..2.4.1.11111014 ' 'Ric" - . 77, 5_ ..1;.... . - - -7. ..: _-__; . 111 ■ 4 "-% 7 :!, 41- "" - l ' - '": .rarA -4/ 9' alirsrafigal " -PiiMINIP■a l iN/0. ,, ,,,.--- ili_.:. te I ih•o••■■••■•• mi . J.." 11111......■ 4 SiliVIIi: . ....., .. , ,■,,!!-.1 . ,--, 4 w ,.. iL laiN..S7I IP UlkiiillieLZIet 41111, i 51.1113 ay.: !?7,..:',- - ..- 'Inz.,...-It , .....: _ % _Ai "... immilool, WIIIITO .1 A ..-••=40 4 , .-..-,..._ ..-zt.,--,--.4) ` ArghilliBiejlIVNI Ittivolli.4.1 ... , - --•.._ _____ I -1•11.....8. _ur.vollml a - 04 1 j 1.)1 .; , j r 1.2 .' i , , . a P 4Migit* l' - .is . ; ::‘,ItirCk• g Illeno• ' r - ' ici 07' 4 I i A ` carldilriiiiinniPlyANVIINE: ilA i ? F o rk ; : ' -1 I ' Ll ' ' ' laiviullis -461 _-_-,---,. _„..,--- .__,-_-_: _ .,..„-._ . a .. ...!..z ..t.4-..._ - •!n.IN 1 1111r,z1 1 41, -j1"Z -. "44 . •Mt ° ' 111=Iii.UPARIldE211110 grieatad Erg ----4.4.- - —le, Ir - ,----- •-•'""-....- ----- --;:7 - ..:::- - •' - :" ... ; , litliu--"- -- - ...IR a :tUri isilr SHISSEPIASPIPPIe.11/r 1 /11;lej111411k a imp — 1 wuwir2.421... zirr.,...= rapt.: r 1-.-,- ...-- iltilliF M iii A ) it ..U. '- at 1 rit la MIMI, 4 1' elk' ir ..,.„.,,..•.•....... ,„,,,:,,,,„,.,,,,_,.. sal a ft i el Atli - e illl • .. ..._ ciiiit , _,7 IIIINI , t it4111 P . til k - ' - ‘,...,""i0" -- ...-‘: - :::"..,:%‘..'-',"NrS.7.--4 . 0■1. 1..—.- V i t ' I_ , : m ola w il ,..... rr l irs:_ -- . : 71 11, , i , A . . -- -.',1::':7.'1.--7:1- ''''':-.7.,7"..NN''-'7,'7.!•,•.1."17-!----'-',7-7I..-----7-1'...21:1.:::':‘-'" /i l i k ri "lri... - ....• ... $1 '. cif//4 . _ ,, -- 7.-. . •■-:" '• .. . z--.. ..., - - - ' ''' s ' - ' 1/2- ' ,, s , At . ,,ML,N-meilr - ,,r.•"•-" r ' ' - il , I Shallow Groundwater Areas _ aellow ............ . Ahtanum-Wide Hollow Basins - 4 it - „.-.. , : "400--- Elm gni -.., 4 • —74g..„.• ,, , • ,rit,.. , ....._ — . ..- , • . y .1 .....1 .' 4. --, •••••••••• '. • lie , , it ..... ,.. 4011, , h4 - ....- .___ • „ de i - t • 1 .1.--- _ A ii.e . ..... I 7 . .... • - .. .. . l 0 1 / .rde .: • ,...., olatilurm . .. 1 -..... Ii i ... 4.--. ,„e -.pad . i • 1 • Noh. ''' .. - -,., , dr • fir ir dr' .,■:..:. . Oft 1.- , IIQ 646 WilrliWI' --... . _ ..., • AP j j,, --,-, • -, • $ 0. 0. 17 7 •: s.. :'' ••• .0 ....... . - m oon- . • • -, ,.... A. •• . :•.--- $ z•• . •.. - if ,• ,, • : 4 1 ,• .., 4,,,,. .71111k, • ... . .., . - • I . ei ta ' ........:, A. . • _ .A. A. • 414 • .- .1 11 4r otii.1 .* *. iiiiii ,„ „hoh.. '• s _ 1 - 1 - ",4 'ft r - 1 = - 1.,i i....- - 111... • p,‘ " - • • • . • , • ...- II .. -.1111 •••4;a. a a 11 TH , ......... 11 1 0 611t.- 7 . • .- A.' _ ._.,. 1111 111111111111h ukti s 4 ., ....• 4.#4.1°P411.... •-• '4' - --- ,... ••.. • ' . '' . . . ' 1114 . 11111 , 11 f r. - 41111111r ''..- 1 ' .°04111111.161. - p. . . - - c • ' - I„ - " " VAR "I 1- " .• N,..a i .... . ' Mr so j% .,- 4. d.z ■ •• , , . ' 01 - -,;•.• il•- ... -, , - S ,ir- ., or ,.,,,, 4r- .... ..• - air' .--2-A10' .41pik • . * ...-- . . ilimiN -...,.. , illauri. Illihrt.t. .7■Nor ''' ---- _,.. - .,,, .--11114re.r. ,.. heir 014 Nill -- - e . --- . I s: : • ., 0.10 — i ••• i I • .„• . • ' • • • 7 . t i 1 .... • . . ; ' ; t . • • 1 • , .... .... I iii ...•••••• ,46 ' 4. • 41, ' Mir.11111.110111.1.1. . Ahtanum Creek Folding U111 MI 01 Mk Over Flow Ahtanum Creek un 1111 Channels Ahtanum Spring Creek t Bachelor Creek Ahtanum Creek Mu trill Hatton Creek Ahtanum Creek a Canal Hatton Creek Cana la/ - Bachelor Creek Ahtanum Creek lll/ Spring Creek Um IA Bachelor Creek 1711 - 1W ,„.. MI 1101 __ = O mil 1 u L \-- \ (-I 1101 I I lW __ MI IJ! fM MI us IIII ills Of Ha UN i I MI O ale 1/1 WI Iw .. / MI III ION WM 1010 UM / i• In MS w Iw UM a 1111 t0 is MI SS Ia1 MI e^ .Rap Ra tiw , •\ , - "Wild per ' aortp B►dRdR,lrvlsy In ..d• • F Rd , IL I � itEtrdRA :_ yl "' �- " 9brt Rd OEM Rd - _ • � .7ii � r ,, , i r � dot 4n m RihrbilR! • .. E P. %,. • " ••, - , RI /ta[tldfid 8M4vnea tk( TTTTTT��� i 941t . 1 6 - • -. ..L e. .. N a n C 'li It ~ ` 1 I , p ' • Minn I f j \ 11 sUnlawi tYN m ly , f 1 I ! I l I 1 1 1 I 1 1 I ; I ,� I 4( 1 \ 1 \ I 1 , • t Historic Stream & Canal Locations VS Current Stream & Channel Locations LEGEND 1911 stream location N 1911 canal location — — GGG� IN 2011 stream location . .- —= W \ E 2011 canal location '� , Contours S Il 1 c 1 1 4 hik . . • Nilio. , 11 i N fi i I wii f i iii r p - - • • • • \ SUM►�ITVIEW _- � ` „. �; -•• ` , a te; �`�. --., s 1 , l : r \ TIE TON DRIVE lo : ■•• '.° • • to- ` op ri • d i k -.. 1 i 1.0„,_ • . . rill %Ili WIDE HOLLOW RD i • J 1 ` = 1 • . '..... q OP- Plur , .4. -- ..1 Pi ALIT. "Ir Ailt 1 MIS • I 110• jile.71111Irrt&makW- IlL•••■ - . ' PIN imunii I •iR • .�� r• • •• I °a C � 4 f e l ,/ ,47 1 : 1 !: . I • Wide Hollow Creek Vegetation An example of the progression of willows. olt. •••• , ■ . lia ' 't#IPV.T.r..4.17-,...i.-. --apsiariv. .......... _ - - .:. - f-- i ms-rur - 7 7 7 'I ' •.• i • 11947 - . - * • 1947 . 1994 _ 46,- ••• - . . i 4 11 1 010 '11 ilit - int -vs ii . "Iiit • ., ,;... J.: . I, t • 0 - - "P3 , .. -. ''.4 . , , s - J . - M - . I ' - j - .. ',- w 4 ' •"' ) ..., c; ,, . - fr„,,, ., .. . . - - - ' al , _r____'", (../ 1 '1. 4 . 4 . ;••-" . ...... - ,„ ..: ' i • il . -. .. • , • ,,,,_ 4 I . . : _ ._ . ,I... a 4 11 o 7 ' , ider ar.; aGatoarii4•17 • ,_ W. a *1- , 1 r -.; _ ,-.00*.. ■ " * ' . . ■ t , _ ‘..i r l aw-o / r • . ..7-5- . . . .. — --..i. ,.. .10 • ' N .. ' . I ' " ' .." . . ' . . ■ ' • ''' .. ` ... ••• II , 11 " ' i 7:: .,,, . ' .% • " , .. . t . r . - . 'I . -e ' • 'A , —. . Or 1 Illi • 14100 vt ; . — '• ''''' ' 41 '4' . -- ......■... , ...' st„.... ,, IV l . . ... -.. . f': L•-r-s ' NE* 4 .., . . • ',4 . 1p IA g 1 ' , ) 1 4 , • . .) 4 - ,„ c eesi- a • - " .„,...---.. cm c , . t •v 00 0_ _. _ ........_ i • I .••■As•••■• ...:1-,, • • ; . --. I 'rt ,.. --.. . - -.'i,.-‘, .1 ••- . L 1 ... -.., ..., 1 1 , • ......‘,...4.. -,'. .... : i-.. .... , .!...t-- . ... . . It- - - •-.........;- . • . ' .. • -. / . ' A % it : .0 -, - • I -. li I . ' - i. le, ,' ' r.. !;.7-Ah '3;‘[.„ - ,,.., :, - ....- ,1,-.0■•,, . _ • _ „ , • „ ,.. - 1968 " ' es .,.; . • -7.a , ,,,, ' ' 1* 2008 - 1 , ..d. ‘.. A -. • I. i .... , 1 , . , I a I - 'r• . . . . - , . .... Mil I q - -,...., '-,,-;,, - 1 ,. ..... _ - "o• N. R . i .? .-‘• - . vr --IWIef- . t, ._ ._ ,., _ - . . _ . . . ' • ' ''S , . • I in IC. IML - 1 . la 1 to - . 1. • ' /4: - X '4i ' , • 1.' , * . or i . ' . 1 1110I• , , • ir ' .... • - -.- 6, 1 " -(,4 ,- . -, . . ' , • . . .. . . . I .",.- ....-,.. . 11,114 • At . . ' 1 10` v ' T:ee 060 . •'' A.i .1,,- a . e 41r!afilliklit ..-.. -V14. :,..... r . . , .. ... ,.:„.......„, ._ ,..........1/4 , T... I ...-. - .. -VS • _ . A EMI :Till 1 : ,,.. ; ........ i l , ., „ i . — , I: - - ; $ ` ' . 1"... . 1 , ... , . t '' • : _.. ' „ , '341 - — - . c. • — ; , • , .. p• .. . '''' , . \ t. .. ' • • — '' ' • .,__ , . I:- ' • ., ...- % ,, ' •ri. • . ...., i Ni - '''-•. - 2■.. *41.7 . *I 'I - Wide Hollow Creek Vegetation Location: - - . # 1 Washington Ave. between 16th Ave & ;I .'. k._ NO lik 24th Ave. City of Yakima. - g Issue:} I EMI i u _ ; it Woody debris and other debris has /is '' I• 1 , 1 building up within the streams floodplain. ti• - '' 1 7, During high water events water flows pre - y I • , r .�i maturely out of the stream channel to the `' - .1�'i }• South. - Remedy: II F ' 1106, ■ f _ lit NM Remove woody debris and other debris to reduce flood risk. AI , ... * IV" 4I 'Vt" , fit 1 *k ' ' "', - f� . .fti - C',, ,r.._ :- I it r ' _ - � • - ` } L Iiiiik y \' ' K j 'p ‘ 4 ,- r r y,. r 2 . �` � I�. • 71 1;-^ i4 .. ,Q yY A 7 k iii - f i �n �./ '. �i�+ May. ; 1 ..�„ - - 1R•l „_.. f, Wide Hollow Creek Vegetation Location: , ` 4' • - . F - t t: ' .r_ '' 1 L r r T .- Washington Ave. between 24th Ave & , r ,� _ A .� l , � _ ; - ' .. '" 1 r. t ,.� ' d 36th Ave. City of Yakima. 10 ,. 1 ! . . ` y +►.t c _ s . ;3 _ ISSUe: ■ ,.c,1 ` 1i - _ ll-' - - Woody debris and other debris has/is .. ( . irk N building up within the streams floodplain. � ' �.' `` ; _! , I During high water events water flows pre- g p � — - maturely out of the stream channel to the _ OF 1 i: South. - ,., e mrs, t ■ _• W. ,- - �' NM Remedy: Remove woody debris and other debris to .5, { �" R 4 , 1 reduce flood risk. A V , ,- ‘ ,... _.: e i :4 4 1. +4— .....,'. - --- • � 1 A - ' � / i ^ X1 T ,, 'L .,r •. { . IMO *4 .. ;� ` • r '`-�— j , . � .�` t��� , _*.A� _cam �_ . -, .de • . t , i: ' _ 1 Y E 5 ■ /. • , 7 l . ' '•gy m . - ` 4 - - n ,' Wide Hollow Creek Vegetation Location: — I • 1 I .. I -. _. x t 1 . 1 �' Washington Ave. between 40th Ave & a " $. y 4 - -. 48th Ave. City of Yakima t< I.., �_ ' • 4 Randall Park Issue: ( - l ' I t d l f • Woody debris and other debris has /is •. .- building up within the streams floodplain. { i ri Beavers have constructed a dam across ar,1 Ll ' the steam. During high water events water :. -'... flows prematurely out of the stream chan- - ,s ' -- nel to the South an area currently under ,` I Y development. ,v, .44 Remedy: Remove woody debris and other debris, pursue relocation of the beaver and re- move the dam to reduce flood risk. 1 .- . t 1 �� -+4444 •• 411-..41111 l I . - « ' Alliiroc / .�,. c . � {4, « ~ ice' . - _ . i .. j `, ' ail ` � ,4 - s , �, it f . :r.. - . - : i : 770 * ,... .... z : 1 / /..7 : :, / ' 4 . .%..4,,,ii ,<"*".' , :.,,,.g: . Y• 11%.44or t � w _ a ` \ -N --1 a. R w r a l 'y mil. • _ i; � .�.�� .� q - • 1 1zC ws is 'b. - ...- @" - •A , ' x . •. 1 F 11 -_ •• y C� sue:' > ?,7 y. -. � { i. + N., 1 „. 4- J c A i' i a ' . . . bl. , , ` it -<. ,Yi?' .../ad •• L.5 i • conveyance at this location will make floodwaters travel downstream faster, and with more quantity, potentially causing higher flood hazards in more densely populated areas downstream. Other alternatives, such as lengthening the bridge (i.e. additional span), only improving the conveyance to allow passage of the 10 year flow, or allowing this road to be impassable during flood events, should be considered at this location. Also, raising of the road at this location, without improvements to the bridge is not recommended as the backwater from a raised road would likely cause water upstream to flow into Hatton Creek, which is even more undersized for flow conveyance than Bachelor Creek. Bachelor Creek - Bridge 97 25 Year Flow Existing 100 yr flood plain water Waal t _ 1410 . .17" -bt' fAITI Md t w 1615 1 - ■ �' 6 - ... _ post -excavatlon water level 1610 FA Q`A ' ' • T `e 1406 — - -- 010 400 600 800 1000 1100 StaIOn 161 10 Year How 100 Year Flow illik .. .�- . water Waal 4 existing water Waal i I p. -e avation water level paatexcaaatlm water level 1610 - 1__ 500 000 400 1000 1100 0 400 600 000 1000 T 1100 810044 00 814o0 (p Figure 9 — Case Study Bridge 97 Profile Bachelor Creek - Bridge 97 10 Year Floodplain r" b' ? ..r-l? Existing ' Post excavation Ar pm x .' •' ," "'F. 25 Year Floodplain • Existing Post excavation r sin 4- . t a� t 't a .r . 100 Year Floodplain 9 0- i z Existing • Post excavation r .R.J I ■ 1 .1 1 s 5 , . ,......... di g . i Figure 10 - Case Study Bridge 97 Floodplain Shaw Creek — , - :-1 — t• i t I.° ,ca 4 • — , -` { I P t l , I . m ' _ • .• j -_ - � � � • F • . - S % Shaw Creek _Shaw Creek AS Fi ure Al . 100 -Year Flood lain aedHollow Creek m 9 p — Shaw - Wide Hollow Overflow _ Wide Hollow 0 _ for Existing Conditions QFee1 g —Shaw Creek Overflow r---1 100 -Year Floodplaln CONIULswwrafwd:. h ,,,, ! ir 1 ! , *. , i .. , — i• t ,_,_ ... ,„:' r _ • {[` ? • _ .... J� II r Li r . . * t ies . ■ i ^_at . _ 1 1iY dEaw �rYlMr I' Ii „al w- - - - 11ay F 4 Id Ndo aadYnr — d r , t -S7 • 7 - • ~ - i I i. • . . i _ • . _ "I w j S ■ Linn of Existing Conditions \ \ 11/0yr Fbodploln on Wade Hollow s 1 v. - . ifitiar, WEST Figure A2. 100 -Year Floodplain for Wde creel( High Flow Bypass Alternative #1 Wde Creek a 1 ' eel 9 YP Cl 100 -Year Floodplain CONSULTANTS. INC When Will It Flood? Flood Chance % Chance Frequency in any year Over 30 yr (years) mortgage 10 10 out of 100 96% 25 4 out of 100 (5% 50 2 out of 100 46% 100 1 out of 100 26% 500 .2 out of 100 6% FL 001) UA I SCHE_llA TIC ✓ BASE FLOOD 1 o FLOODPLAIN FLOOD \ \AI - +FLOOD \ \AVFRINGE = BASE FLOOD / 1% FLOODPLAIN SITRCHARGE NOT TO EX CEED 1.0 FEET . Rating Exampks Type Bldg. Coverage Premium -1' at BFE +1' Pre - FIRM $100,000 $6834 $685* $683' Post- FIRM $100,000 $2546 $816 $451 Mfg. Home $ 60,000 $1.42 $t)65 $410 Ulm A Zotie $100,000 submit submit $1191 r Commercial $150,000 $6396 $1641 1711 X Zones $100,000 $441''' $441 *' 3 $441'" 'Pre -FIRM: EC not required, but can be elevation rated '' In Unnumbered A Zone, $536 it ?'> ground; $276 it 3'> * l`' Can be less with Preferred Risk Policy ;e.g,, $233 tar $100,000 uis, Estimated Flood Insurance Costs IN )IIO;, f _i ii i ( ) \,.•_'r 'l<M :tl r .P.-,•r _ill S I(Nl ( H II 1 ill r<.' _'rY' ∎I \ i,..,ir AIr)!'r:,.I..r, • J ft c1!i J`l Err — a J( ) I ,O ,1 1 7( 1 fr 1!!)(0': ,' III ,.,. � J _j,"i, 7 {i( ) 1 1 fi. abole Err = ':;;"45 S. 3() 0 ft at BFE = S8 < ( $24 -'1 f_ _1 J J 1 = r �r C f^ r _ � r 7 -.) ft _1JJf_. Err - 7_),. - ': 9 --, ( -5 ft - lbo'Je Err - :)O ; I I ,f _O Below -Grade Crawlspaces & Insurance Rating Floor Joist r _ BFE Foundation Wall L = 4 ft Maximum —T / Flood Vent -- - Lowest Adjacent - + :: Exterior Grade (LAG) "44. __ D = 2 ft Maximum -,____ Crawlspace 'T ?rr - Interior Grade ? ' Figure 3 Requirements regarding Mow-grade crawlspace construction. Flood Insurance Requirements for Typical Residential Sites in ..,_,--: L . ...-..,-,,.. ��/ ` < , Example A: ��_ ;�. - � _- % Example E: Property in SFHA „. se MO • Structure located in SFHA sio \\ I although on high bluff. but structure is not 1:- = Insurance apt required. \ ,` , Lender must require insurance 1 ,._ 1 but buyer can request LOMA. 7 :1" -- -- t _ \�. Upon approval of LOMA. buyer 1 ` ` may receive insurance refund. Example B: I. \� Y .� _. Structure in SFHA but substantially elevated ■ • i - : Special on natural knoll. � ,.' .. �; Lu , - Lender must require f / r ,r %"/� insurance. Builder can ! � Flood � g request Letter of Map 11": �' % � Amendment ILOMAI. %i % / . � Hazard _� � A rea _,_ . \y Structure in SFHA but � subsla ntially elevated on fill. .�\ • 111 Insurance initially required but Structure C: buyer can request LOMA. ure partially �' Struct / �� Insurance may be refunded. located in SFHA. % Insurance always f i -'!1 � . required. -` j `/ i / `` 1 f! / -, �!� - a Example G. n a 1 Structure in SFHA but e - - �" �� " elevated through means %/ ■ \ 1 other than fill, e.g. posts. /.��� • • • 1 pilings. piers. etc \\ ` Insurance always required Z� /.. Exam Ip a D: - ,- s Structure located in 1� : : :: SFHA but not elevated. „-----------__.,/,--------- `s Insurance always required. ` ■ _ ` �" /.?� 1 � .. 1 \ ' ft `; it:.;-- .` � \ \� Enhanced Flood Risk Assessment Analyses . ..._ . , , ... ... • Enhancements could include: • Risk Assessments at site- specific � , `4. r locations - ! 1 • Incorporation of locally - provided -, • inventory data (first -floor elevations - and /or parcel data) Total Losses W • Additional sources of flood depth , S1- 4k g rids •S20-53c • SS4- • Supplemental HAZUS analyses or :� p :.g. 8 other types of analyses Z "g -e ail. , I ., Q : . f. co a s 4:It IP„'-, - 0 Total Losses SO S1 -4k . :$5 -19k 0 S20 - 53k 0 554 -88k Percent �hance of Floodin over a 30-yr Period Grid • What is the likelihood that a specific location will flood at least once duringa 30 -yr period? • Usingthe PercentAnnual Chance of FloodingGrid as an input, perform the fol lowing ca lcu lation: 1 — (1-p) ...where "p" = percentannual chance of floodingand "n" = 30 Percent Annual Chance Percent 30yr Chance i jRi 1 � 1404 I 1 ... � t ' `'' ■ . .• IP,41itf # - : � y •20 r IA ® 30 - ♦ 00.2 -2% X 40 - �` �� 00 50 - ' : '' ' 04 -6% 06 -8% MI 70 -80% v i - y •8- 10% •80 -90% • 0,41k _..,1 •,0%+ IM 90°k + Fl oo d Ri R epor t El emen t s Estimated Potential Losses for Flood Event Scenarios Total Inventory 10% (10 2% (N0 -yr) 1% (100 -yr) 0.2% (500-yd Annualized (5 /K) Estimated Sot Total Dollar Losses' Loss Ratio' - Dollar Loses Loss Ibfio" Dollar Losses' Los Wdot Della Loses" Loss Radial Dollar Losses' Loss Ratioi Value Residential Building/Contents 594,495,000 77% 5:3,439,000 11% 513,571,300 14% 519,273,000 20% $32,925,000 35% 5176,030 0% Commercial Building/Contents 515,127,000 12% 52,112,000 14% 53,225,000 21% $4,337,000 29% 54,925,000 33% $109,000 1% Other Building/Contents 5:3 073000 11% 51,663,000 :3% 2 :95 000 17% 4 r,/C 5 53,620,009 28% 55,430,000 ... 579,000 _- Total Building/Contents 5122.695.000 100% 514.211.000 12% 5111.991,000 15% 527.230,000 22% 543.2110,000 35% 5364,000 0% Business Disruption° N/A N/A $760,000 N/A 51.259.000 N/A $2.011.000 N/A 54.074.000 N/A 518,000 N/A TOTAL* 5122.695A0D N/A 514,971,000 _ N/A _ 520.250,000 N/A 529,241,000 _ N/A 547,354.000 N/A 5332,000 N/A 11111:4".1111/1 41 . , , IIIF 1r JO' - I ...-,,,,,,„„ V . . Ito t\ * • . N • 4mi Ni lik. it ..s . . ..., , . -h....1SL ..... k il .- _. . . . 16 , Zr e 1 , . * * 41 . t ill 1 w . ilt0 iv .. , 1,... . . . 41,,...... I li ttoilt .... .k ,.. ... . ii• 4 , > • , 0 L R f Iry i 14 1 . \ ' 4 1116 , ••• 4 11 ''' 1, s, .,, ■ r ...- . 4 • -.,. T -- 4 to .... * ,.A. t _ 1r — • ' , ■ -,, < " ,I. - ,, L N , 12 , 1 0 . . .,- . . .. * • i -1 t. ' , . .' % . - 14 . , ... , • • . ,..• . .. 11111k.11) • _ . ..., • t -• Aa 16 i . rr .4, t , sr , . . Cc . Image D c earth .- ..- V * - . A,, ogICal Surve • • _ 1 • ' N . I 0)c`.01 Googie , GO 1 81 - : earth feet 3000 / - Di / - a• a cff '. St `P r Distributed t th . :; < Meeting .3 CO -.. II. C'c li - i i v o .,,, i i Q • 4 • ‘4 i • 4 . tir ,.,. y .. si, •„x ....1.‘ -, • a C . A . . 4 • .410 - N W 0. ' 41 S t * 414 r` ,, ,....1.4 44 1111 . '' r 1IF 111, ! it w , rt 44 dekk • i . ' ' Ili a R . _ V— , 1 f , -,.,,; "" , -4---) CO CD t ` ;. "; ` .. J . fi - � i • IV' t• r