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HomeMy WebLinkAbout4 - Recommendation on the Stormwater and Flood Management Utility Master Plan Update CITY OF BOULDER WATER RESOURCE ADVISORY BOARD AGENDA ITEM MEETING DATE: July 15, 2002 July 11, 2002 SUBJECT: Stormwater and Flood Management Utility Master Plan Update REQUESTING DEPARTMENT: Ned Williams, Director of Public Works for Utilities Bob Harberg, Utilities Project Coordinator Alan Taylor, Floodplain and Wetland Coordinator Douglas Sullivan, Utilities Project Manager Donna Scott, Stormwater Specialist BOARD ACTION REQUESTED: Recommendations to staff regarding the adequacy of the policy objectives and action items to be completed as part of the update to the Storm Water and Flood Management Utility Master Plan. FISCAL IMPACT: None PURPOSE To determine the adequacy of the policy objectives and action items to be completed as part of the update to the Storm Water and Flood Management Utility Master Plan. BACKGROUND The city's first and only Comprehensive Drainage Utility Master Plan (CDUMP) was adopted in 1989. The 1989 CDUMP addressed flood utility problems and needs in the area of capital improvements, hazard mitigation and stormwater quality. Recommendations were developed to deal with the following major problems: • Inadequate revenues for capital improvements identified in adopted master plans for the major drainageways and storm sewer collection systems; • Lack of a complete, fully integrated flood hazard mitigation program; and • Lack of a stormwater quality program that assesses and mitigates stormwater impacts to Boulder Creek and its tributaries. The master plan has not been updated in over 10 years, and staff has identified three major issue categories as follows: • Stormwater Quality • Stormwater Drainage • Floodplain Management ANALYSIS Stormwater Ouality During 1999 - 2002, Boulder's Public Works staff has participated in a regional approach to stormwater quality planning through the WASH program (Watershed Approach to Stream Health). Boulder County Health Department has provided coordination for the program, with active participation by Boulder County, the cities of Boulder and Longmont, and the towns of Superior and Erie. The cities of Louisville and Lafayette have also expressed interest in the program. A major factor in development of the WASH project is future compliance with the new federal stormwater regulations that take effect in March 2003. These regulations require implementation of six programs to manage and improve stormwater runoff quality discharge from a city's stormwater system to surface waters. Boulder has an obligation to address stormwater quality issues under these regulations and is working in a collaborative fashion with other communities in the region to reduce pollutants to surface waters. The WASH project seeks to protect water quality through regulatory compliance and cooperative, regional management of stormwater issues. The project has successfully proceeded and has produced a number of work products, including the following: • Drafted a proposal for WASH Stormwater Quality Programs that included the six management programs required under the Phase U Stormwater Regulations. • Completed a Memorandum of Understanding (approved by all WASH participants) • Participated in state of Colorado stormwater regulation and guidance development It is anticipated that the city will enter into a permitting arrangement with the other WASH participants. This arrangement will outline implementation of a stormwater management program and joint agreement covered under a Colorado General Stormwater Discharge Permit. The primary stormwater quality issues to be addressed in the master plan would include the following: 1. "Comply with Water Quality Regulations" 2. " Reduce the Amount of Runoff' 3. "Improve Quality of Runoff' 4. "Save our Streams" i Stormwater Drainage The last stormwater collection system master plan was completed in 1984 and is out of date. The city will address updating the collection system master plan as part of the Stormwater and Flood Management Utility Master Plan. Many of the study's recommendations have not been implemented and will need to be reviewed to assess their current priority. In recent years, Utility's focus has been on stormwater quality measures rather than replacing existing infrastructure. There are several stormwater drainage issues that should be addressed as part of the master plan update. 1. "Maintain and preserve existing and natural drainage systems" 2. "Reduce and manage developed runoff' 3. "Eliminate drainage problems and nuisances" Floodnlain Management A study session on floodplain policies was presented to City Council on January 29, 2002. The study session provided Council with background information on local floodplain policies, an analysis of floodplain policy trends and philosophies, and staff- recommended floodplain policy objectives to update and adjust the Storm Water and Flood Management Utility Master Plan. Council members generally supported the recommended guiding principals outlined by staff that included: 1. "Preserve Floodplains" 2. "Be Prepared for Floods" 3. "Help People Protect Themselves from Flood Hazards" 4. "Prevent Adverse Impacts and Unwise Uses in the Floodplain" 5. "Seek to Accommodate Floods, Not Control Them" Council approved the study session summary at its agenda meeting on March 5, 2002. In addition, Council members agreed that greater emphasis be placed on nonstructural measures (that offer direct and immediate services to residents citywide) to better balance the city's floodplain management program. Updated floodplain regulations to address redevelopment, critical facilities and storms exceeding 100-year levels were also supported and subject to the consideration of the results of additional analysis. The following questions needed to be addressed: • What would be defined as critical facilities? • What is the impact of the 500-year floodplain compared with the 100-year floodplain? • How would the regulations be revised to address redevelopment concerns? • What impacts would the revised floodplain regulations create? Council further recommended that a public hearing on floodplain policies be held to obtain citizen input. Given the outcome of a public process, Council acknowledged that II recommended policy revisions could change to reflect citizens concerns and community values. Council also requested that budget impacts associated with increased activities in nonstructural measures be identified and evaluated in context with the current capital improvement program (CIP) schedule and components. Council also offered recommendations to enhance public outreach and education with the posting of flood warning signage where appropriate in public rights of way. RECOMMENDATIONS The attached documents summarize the policy objectives and action items to be completed as part of the update to the Storm Water and Flood Management Utility Master Plan. It is requested that the WRAB review this information and determine the adequacy of these policy objectives and action items. ATTACHMENTS: Attachment A: Stormwater Quality Policy Objectives and Action Items Attachment B: Stormwater Drainage Policy Objectives and Action Items Attachment C: Floodplain Management Policy Objectives and Action Items Attachment D: Boulder Floodplain Properties Mapping L APPENDIX A STORMWATER AND FLOOD MANAGEMENT UTILITY MASTER PLAN UPDATE STORMWATER QUALITY POLICY OBJECTIVES AND ACTION ITEMS July 11, 2002 The following is a list of policy objectives and action items to be evaluated as part of the update to the Stormwater and Flood Management Utility Master Plan Update. 1. "Comply with Water Quality Regulations" (Regulatory Compliance) • Implement a stormwater management program that meets the requirement of Phase II Stormwater Regulations. These requirements can be met in part through participation in the Watershed Approach to Stream Health (WASH) regional stormwater management program as outlined in the WASH Plan. Action Item: Determine resource needs for WASH program implementation. Ensure adequate funding and staffing of each of the six minimum control measure. • To implement a number of the minimum control measures (MCM) required under Phase II Stormwater Regulations, the city must have adequate legal authority. This authority is primarily focused on the city's codes and ordinances. In addition, specific MCMs require ordinance language to implement programs and provide basis for enforcement. Action Item: Evaluate adequacy of legal authority to implement Phase II MCMs and identify appropriate code and ordinance changes required. 2. " Reduce the Amount of Runoff' (Sub-basin Management) • Implement an integrated sub-basin master planning process to provide overall direction for basin and corridor developments and CIP program. Process should integrate flood, drainage, and water quality benefits and the costs associated with capital construction, land acquisition, and ongoing maintenance/operation. Action Item: Develop criteria to prioritize various objectives within each sub- basin. Criteria may include flood management priority (e.g. high hazard areas), water quality pollutant loading, cost-effectiveness, environmental impacts and ability to coordinate with other city projects. Develop a sub- A.doc 07/11/02 Page I of3 basin classification system for water quality, flood management and drainage using GIS. Evaluate cost and resource needs to develop GIS capabilities to support this level of sub-basin master planning efforts. • Provide adequate groundwater recharge and reduce runoff in basins by addressing impervious cover. Strategies to reduce impervious surfaces include undeveloped lands through land acquisition, and Non-Structural BMPs, porous paving, landscape standards, preservation of rural zoning designations Action Item: Develop information needed to assess cost of implementing the various elements of an impervious surface reduction program. This may include the development of a public lands inventory and GIS and assessing the impact of requiring BMP to reduce impervious areas. 3. "Improve Quality of Runoff" (Stormwater Treatment and Pollution Prevention) • (Regulatory) Implement design and development standards, construction erosion and sediment control, which require BMPs to minimize the impact of runoff on water quality. In addition, incorporate water quality protection in flood control design, construction, and maintenance projects. Action Item: Evaluate the use of design standards such as "Better Site Design" and other protection strategies to address construction and post construction development impacts. Evaluate the impact to the development community of various BMP and runoff reduction strategies. This may include the requirement that post and/or redevelopment peak discharge rate cannot exceed the predevelopment discharge rate for a single design storm event (two-year). In addition, define what type of standards to protect water quality and type of construction activities must comply with the standards. Define thresholds and standards for different types of construction activities (e.g. single-family residential, large residential or commercial/industrial sites, redevelopment sites, mitigate for downstream impacts). Evaluate resource needed to provide for design review, inspection, and enforcement • Develop runoff conveyance performance criteria and storm sewer treatment standards. These may include the use of open swales, pocket wetlands, biofiltrations, outfall buffers, in-line stormwater treatment, and detention. Action Item: Evaluate cost of pollution reduction strategies in various basins using pollutant-loading estimates from the Boulder Creek Watershed Study. • (Regulatory) Implement a comprehensive stormwater pollution prevention/inspection and enforcement program. Program should address illicit connections, illegal dumping, A.doc 07111/02 Paae 2 of 3 L municipal operations, household hazardous waste, and commercial/industrial pollution prevention. Action Item: Evaluate effectiveness of existing program including implementation of programs elements implemented by other departments and agencies (Boulder County, Boulder Partners for a Clean Environment (PACE) program, Boulder Fire Department). • (Regulatory) Implement a maintenance program to prevent and reduce pollutant runoff from the municipal storm sewer system. This may include storm sewer inlet and catch basin cleaning, street sweeping, winter road maintenance, flood control structure maintenance, and structural BMPs maintenance. Phase II regulations require operation and maintenance program for all stormwater facilities discharging to a regulated storm sewer system. To comply, the city must provide adequate maintenance of both public system and private system, which are connected to the public system. Action Item: Evaluate effectiveness of current maintenance practices including development of record keeping system for major maintenance activities. 4. "Save our Streams" (Stream Protection) • Implement design standards and guidelines to provide protection and enhancement of riparian and aquatic habitat and water quality. Action Item: Determine effectiveness of existing design standards and guidelines in addressing stream bank erosion, functioning channel conditions, terrestrial habitat, groundwater/surface water interface, and aquatic species movement. Greenways Design Guidelines may be appropriate document to assess. • Provide monitoring and evaluation to assess the impact of stormwater runoff on receiving waters and evaluate pollutant loading from various land uses and pollutant sources. Identification of High Quality Water Resources: Currently, there is no method for identifying these resources. Action Item: Evaluation the effectiveness of existing chemical and biological water quality monitoring of Boulder Creek and major outfalls and tributaries in Boulder Creek. Developed criteria to identify surface waters of high quality to prioritize application of protective and enhancement measures. A.doc 07/11/02 Pac 3 of 3 i APPENDIX B STORMWATER AND FLOOD MANAGEMENT UTILITY MASTER PLAN UPDATE STORMWATER DRAINAGE POLICY OBJECTIVES AND ACTION ITEMS July 11, 2002 The following is a list of stormwater drainage policy objectives and action items to be evaluated as part of the update to the Stormwater and Flood Management Utility Master Plan Update. 1. "Maintain and preserve existing and natural drainage systems" (Preservation and Maintenance) • Implement a maintenance program that clearly defines efforts to maintain gutters and pans, storm inlets and catch basins, storm sewers, open drainage swales, culverts and bridges, irrigation ditch interfaces, sediment and debris traps and detention facilities. Action Item: Assess existing maintenance program in light of this policy objective. • The long-term management and maintenance of detention facilities should be considered to assure the long-term effectiveness of detention facilities. Detention facilities are required for all new development consistent with regional urban drainage criteria. However, the city does not typically own, manage, or maintain these facilities Action Item: Determine locations and easements for all existing detention facilities. Use this information to assess the cost of long-term management and maintenance of these facilities. Specifically consider city maintenance of detention facilities in existing residential areas that have detention ponds that serve multiple properties or receive runoff from public rights-of-way. • Acquire public rights-of-way and easements for all natural and existing drainage systems such as creeks, swales, detention facilities, and storm water improvements. Action Item: The city has recently comprehensively assessed the status of all easements. A GIS layer was developed to capture this information and can be used to assess the cost of acquiring additional easements to meet this policy objective. • Protect the natural features and functions of the existing drainage systems and care for their health to improve the effectiveness of these systems. Action Item: The Greenways Master Plan was recently completed for Boulder Creek and six major tributaries. This plan considered the natural features and function of these tributaries as well as other objectives related to drainage, transportation, recreation, and culture. This approach can be used to assure this policy objective is met for other major drainageways. 2. "Reduce and manage developed runoff" (Regulation) • Update drainage regulations and design standards to improve detention pond facilities and features to better attenuate runoff. For example: requiring lengthened flow paths, pervious separations between impervious surfaces, increased numbers of storage elements (widened swales, incidental ponding on roofs, landscaping and paved areas, and underground storage devices), multiple stage detention ponds, regional detention ponds, and reduction in impervious ground cover (reduced building footprints, alternative surface paving, increased tree cover, and pervious landscaping). Action Item: Assess existing regulations and design standards in light of this policy objective. For example, the city uses the two-year storm for residential areas and the five-year storm for commercial areas consistent with regional urban drainage criteria. The city should consider the selected design storm, balancing the benefits of drainage improvement with the impacts and costs of constructing the associated storm sewer system. Resolution of this issue will be required prior to beginning work on the general drainage (storm sewer) plan. • Require development activities addressing drainage to propose multi-objective drainage systems and corridors to provide for storm water quality, open space, recreational area, water conservation, and other possible functions. Action Item: Assess existing regulations and design standards in light of this policy objective. For example, site drainage designs could be required to convey runoff to landscaped areas prior to discharging to a collection system to reduce runoff volumes and landscape irrigation demands. Natural drainage paths could be reserved on developing lands to recognize natural conveyance corridors having natural erosion features and environmental benefits. • Require developed runoff system evaluation and design based on multiple storm frequencies to ensure that any newly planned system is optimized to be effective, adequate, and functional for multiple storm events. Action Item: Assess existing regulations and design standards in light of this policy objective. For example, the city currently requires detention based on maintaining the 10-year historic release, but requires storm sewers be designed based on the two-year and rive-year events. Three-stage outlet structures (2/10/100) or detaining the volume required to release the 10-Year storm at the 2/5-year rate should be considered. Resolution of this issue will be required prior to beginning work on the general drainage (storm sewer) plan. 3. "Eliminate drainage problems and nuisances" (Mitigation) • Reduce or eliminate nuisance drainage to public rights-of-way from the discharge of groundwater and sump systems and constant flow conditions that may create an icing or slipping hazard or street and sidewalk puddling. Action Item: Consider standards and plans to address how to best eliminate these nuisance waters and prioritize this work with other stormwater and flood management utility work. For example, the city currently requires a minimum 18-inch diameter for storm sewers, but in areas where a pipe is only needed for groundwater, a smaller size pipe might be more appropriate. Another problem is that the development engineer may indicate that groundwater discharge is not a problem. Under our current code, it isn't a problem until it is a problem, so we don't have an efficient way to require improvements at the time of initial construction. Once a structure is built and occupied, it is a much bigger headache both technically and politically to get the situation resolved. Should we go as far as to require all structures with subsurface improvements to be adjacent to storm sewers? Is there a more reasonable way to address this? Resolution of this issue will be required prior to beginning work on the general drainage (storm sewer) plan. • Develop basin area plans to retrofit drainage systems where no systems have been provided and inadequate drainage is present. This should include runoff flows from public rights of way crossing private lands, runoff obstructions resulting from public improvements, improving public convenience, managing frequent flow conditions, and avoiding the transfer of drainage problems from one area to another. Action Item: These issues would be considered as part of an update to the general drainage plan. The city is currently collecting information concerning the existing storm sewer including invert elevations of all pipes. This work should be completed in 2003. It is anticipated that this and other currently available information will serve as the basis for the update the he general drainage plan. As part of this work, the opportunity for regional detention facilities should be evaluated to identify potential locations for creating regional detention ponds and developing options for implementing improvements. Also, should this plan depict improvements for problem areas so that improvements by various property owners could be intelligently coordinated? _ i • Provide a clear point of contact for drainage questions and complaints, education for individual responsibilities with respect to drainage and runoff, and a proactive and responsive organizational framework for addressing community drainage problems and nuisances. Action Item: Assess existing procedures in light of this policy objective. Attachment C STORM WATER AND FLOOD MANAGEMENT UTILITY MASTER PLAN UPDATE FLOODPLAIN MANAGEMENT POLICY OBJECTIVES AND ACTION ITEMS July 11, 2002 The following is a list of floodplain management policy objectives and action items to be evaluated as part of the update to the Storm Water and Flood Management Utility Master Plan Update 1. "Preserve Floodplains" (Preservation) • Implement a policy that recognizes a prescriptive floodplain easement that offers "beneficial functions" for flood hazard reduction, water quality enhancement, wetland protection, wildlife habitat, riparian corridors, recreation, alternate modes travel, environmental relief, aesthetics, and urban open lands. Recommended implementation tools include public land acquisition, private land dedication, and integration with multiple program activities. a) Public Land Acquisition: Continue with the high hazard property acquisition and building removal program we currently implement and enhance this activity to pursue undeveloped floodplain lands or creek corridors that offer "beneficial functions" and other community goals. Action Item: Review the current floodplain acquisition program and funding allocation and assess opportunities to be more effective and proactive in preserving floodplain areas. b) Private Land Dedication: Development applicants are already required to dedicate lands impacted by major drainageways to provide a corridor for storm water conveyance under Chapter 10-5, B.R.C. 1981. This requirement could be expanded to include dedication and preservation of floodplain areas for both conveyance and flood storage, and where "beneficial functions" currently exist. Action Item: Evaluate options with the Planning and Development Services to encourage private floodplain dedications as part of development activities without restricting land use potential, and revising land use regulations to require dedication of floodplain areas serving beneficial functions in addition to the currently required dedication of conveyance zone areas. c) Integrate Multiple Program Activities: Current programs, such as wetland protection, water quality and greenways, should be integrated with floodplain preservation to best achieve multiple goals through centralized coordination and oversight to ensure effectiveness. Attachment C 1 Action Item: Assess opportunities to integrate multiple program activities for wetland protection, water quality, greenways and floodplain management to more effectively preserve stream corridors and floodplain areas. 2. "Be Prepared for Floods" (Preparedness) • Implement a program to update hydrology and hydraulic floodplain studies, perform multiple- frequency storm analysis and detailed risk assessments, enhance early warning systems and multiple emergency notification measures, develop understandable response plans and workable recovery plans, and expand ongoing storm monitoring. Recommended implementation tools include developing state of the art hydrology and hydraulic models, designing detailed risk assessment processes, increasing coordination with the Emergency Management Office, enhancing the early warning system, installing multiple emergency notification measures, and enhancing the flood response and flood recovery plans. a) Develop "State of the Art" Hydrology and Hydraulic Models: Use modem and advanced models to study updated hydrology and hydraulic flood conditions. Develop a citywide floodplain model combining the 13 separate floodplain models for each creek to permit analysis of multiple-frequency and multiple-storm event scenarios that may occur over more than one drainage basin at a time (we cannot do this with existing models). This would allow staff to study the reaction of local floodplains based on varying storm conditions and how the storm drainage system responds to the impacts. Action Item: Evaluate the costs and resources required for updating the floodplain studies for all major drainageways using modern and advanced study models, and identify program options for funding ongoing study activities and updates on an annual or periodic basis. b) Perform a Detailed Risk Assessment: Using existing and/or updated flood information, prepare a detailed analysis of risk to structures and people. Estimates of financial losses and risk to life may be quantified and the greatest risks may be identified for flood preparedness and mitigation measures. Action Item: Evaluate the costs and resources needed to prepare and assemble detailed risk assessments for all floodplain areas to be used in determining the greatest hazard reducing and cost-effective flood preparedness and mitigation measures. c) Improve Coordination with Emergency Management Office: A focused effort to coordinate flood emergency preparedness activities with the city/county Emergency Management Office (Larry Stem, Emergency Management Director) should be initiated to compliment and integrate floodplain management activities and implement updated plans and actions. Action Item: Consult with the Emergency Management Office to outline options and alternatives that may improve coordination between the two programs. Attachment C 2 d) Enhance the Early Warning System: The early warning system is currently most effective for mountain canyon generated flooding on Boulder Creek, Four Mile Canyon Creek and South Boulder Creek. The system should be expanded to provide additional rainfall gauges, stream gauges, and weather stations throughout the Boulder area to provide flood monitoring in all 13 basins. Also, new developments in radar forecasting and satellite imagery may be incorporated to provide more effective and immediate monitoring and forecasting. Early warning monitoring stations could also be provided at additional locations to allow system redundancy and greater personnel access to current information. Action Item: Consult with the Emergency Management Office and evaluate the costs and alternatives for expanding flood monitoring gages and devices. e) Install Multiple Emergency Notification Measures: There are many systems available for disseminating emergency warnings. Currently we rely heavily on sirens and have access to a "reverse 911" calling system. Other types of warning systems include telephone auto-dialers, cable override, radio, tone-activated alert radios, and the Internet. The system needs to be effective in reaching people inside homes, businesses, and automobiles, in addition to people who are outdoors. A survey is currently being conducted by the University of Colorado at Colorado Springs in connection with the Emergency Management Office and UDFCD to study how people perceive the flood threat and how they would respond to warnings. The outcome of this research may provide additional alternatives and options in improving warning notification and emergency planning. Action Item: Consult with the Emergency Management Office to review alternative notification measures and evaluate the costs associated with multiple systems. f) Update and Enhance the Flood Response Plan: The current flood response plan may be updated and enhanced to better educate citizens in how to respond to a flood emergency. An enhanced plan that provides clear and concise direction to public officials as well as citizens will be more effective in protecting lives and making appropriate decisions during a flood event. Action Item: Assess the existing flood response plans and evaluate enhancements and costs for updating and developing improved plans. g) Update and Enhance the Flood Recovery Plan: The flood recovery plan should be updated to incorporate current procedures and practices to meet community needs following a flood. The plan must address necessary recovery elements such as identifying early actions and decisions that must be made, meeting victim's immediate needs, performing building and infrastructure damage assessments, re-establishing critical community services, acquiring or preserving post-flood properties to avoid future losses, issuing building permits for allowed reconstruction, and restoring normal city operations. Action Item: Evaluate the costs for updating and enhancing the flood recovery plan. Attachment C 3 3. "Help People Protect Themselves from Flood Hazards" (Education) • Improve and enhance public interaction and involvement, available floodplain information, community outreach and education, self-help measures, flood proofing options, affordable flood insurance, and emergency preparedness. Recommended implementation tools included making a commitment to the Community Rating System (CRS), creating a Floodplain Management Office with dedicated staffing, developing a comprehensive Web site, and considering a flood-proofing program. a) Make a Commitment to the Community Rating System to reduce premiums for flood insurance and encourage policy purchases, expand community outreach and education activities and implement technical support services to citizens. The city is currently involved in the CRS but has not pursued the best possible rating. The CRS provides numerous benefits to the community beyond reductions in flood insurance premiums, such as: (a) enhanced local floodplain management, (b) benchmark assessments, (c) federal technical assistance, (d) incentive based program maintenance, and (e) qualification for federal assistance programs. Primary credit categories include public information activities, mapping and regulations, flood damage reduction activities, and flood preparedness activities. Greater commitment to improving the local CRS rating is resource dependent and may require additional human resources support (such as added staffing and/or outside contractual/consulting services). While Boulder provides numerous activities that would earn CRS credit, we have not taken full advantage of this program because of resources needed to request or maintain a higher rating. Action Item: Evaluate resource allocation needs to provide further focus on the CRS program, assess CRS activities that may be most beneficial and cost-effective to implement and assign a floodplain manager to coordinate this effort. b) Create a Floodplain Management Office to establish a source location identifiable to the public, provide adequate resources to implement and maintain required CRS elements, maintain required records for floodplain development, manage and utilize flood models for risk assessment, and offer direct community services and assistance for providing floodplain information, education and self-help flood protection consultations. A floodplain management office could directly coordinate with and compliment the activities of the Emergency Management Office (EMO) by providing educational and planning services for floodplain preparedness in advance of flooding. Such an office could also be coordinated with Boulder County floodplain management efforts to recognize the interface between the two local governments. Action Item: Evaluate resource allocation needs to implement activities that better support community information and customer service programs without creating a new and separate program office group. Identified activities may be distributed to appropriate departments and work groups. c) Implement a Comprehensive Internet Web Site for floodplain information and e-business. With the high level of Internet access and usage in Boulder, this tool could provide direct public access to important floodplain information, such as floodplain maps, letters of map revision, flood insurance information and a record of elevation certificates for buildings. Staff Attachment C 4 released an interactive floodplain map that allows a citizen to search for a specific address to be shown on the GIS-based floodplain map over the Internet. The Web site may also provide valuable links to other floodplain agencies such as FEMA. Action Item: Evaluate existing information sources that may be cost-effectively converted to an Internet format and identify resource needs to create additional and enhanced Web site information. d) Create a Flood Proofing Program to help citizens protect their property through onsite staff consultation, the provision of self-help information and possible low-interest loan programs to construct flood proofing. Action Item: Evaluate opportunities and possible costs and funding mechanisms to create a flood-proofing program that may assist property owners in protecting flood prone structures. 4. "Prevent Adverse Impacts and Unwise Uses in the Floodplain" (Regulation) • Update and develop appropriate regulation and land zoning, open land preservation and acquisition, multi-objective planning, acquisition and relocation of high hazard structures, and prohibiting unacceptable encroachments. Recommended implementation tools included adopting revised floodplain regulations (to avoid unacceptable floodplain impacts, create standards for critical facilities and improve life safety factors), consider guiding principals, expand property acquisition and urban open land preservation, and enhance storm water management activities. a) Consider Recommended Floodplain Regulation Revisions that include: • Maintaining the current high hazard zone standards prohibiting new structures intended for human occupancy. • 500-year protection for critical facilities (consistent with development of the new Boulder Community Hospital and Foothills Housing development). Critical facilities would include among others publicly owned buildings, hospitals, managed care facilities, and schools. • Prohibiting adverse floodplain encroachments and impacts that would increase flood depths (consistent with the conveyance zone restrictions) or velocities, or reduce flood storage, to maintain the current carrying capacity of the floodplain, prevent creating high hazard conditions or increasing downstream flooding. • Requiring safe emergency access routes to buildings during floods and ensuring that functional emergency exits during flooding are provided from flood proofed buildings. • Requiring multiple storm level protection measures to account for flooding from storms greater than 100-year magnitude ■ Lowering zoning densities in floodplains and offering possible transfer of development rights to avoid new floodplain encroachments • Adopting a floodplain buffer to address mapping uncertainties and avoid future flood impacts. Attachment C 5 Action Item: Prepare a detailed framework and benefits analysis of recommended floodplain regulation revisions to improve local floodplain management and initiate public and board review process. b) Consider Guiding Principles to apply to floodplain mitigation planning that support multiple objectives, community goals and public involvement. Such guiding principles are emerging from the Greenways master plan, and the IRP and CAG efforts on the Fourmile Canyon Creek and South Boulder Creek master plan studies. Action Item: Develop a compilation of guiding principles to consider for floodplain management based on IRP and CAG recommendations, the Greenways program master plan and other community and environmental objectives. c) Expand Property Acquisition and Urban Open Lands Preservation activities for the most hazardous floodplain areas and areas with beneficial floodplain functions. Such acquisition applications would be for non-structural floodplain management and would not involve land purchases for structural mitigation (such as excavating channels). Action Item: Review the current floodplain acquisition program and funding allocation and assess opportunities to be more effective and proactive in preserving floodplain areas. d) Enhance Storm Water Management Activities to ensure ongoing monitoring and maintenance of drainage systems and.flood areas by clarifying specific maintenance practices for designated locations to ensure that Open Space and open lands preserving floodplains are maintained differently from improved drainage facilities. Action Item: In connection with general stormwater drainage maintenance policy recommendations, assess existing maintenance program activities and priorities and adjust as necessary to address this policy objective. 5. "Seek to Accommodate Floods, Not Control Them" (Mitigation) • Assess and implement planned and monitored system maintenance, nonstructural flood proofing, opening non-containment corridors, overbank land shaping to train flood waters, and limited structural (channelization) measures at constrained locations. Recommended implementation tools include updating mitigation master plans, reevaluating priorities for mitigation efforts to focus on high hazard mitigation and citywide efforts, and carefully considering the need for structural improvements. a) Develop Updated Mitigation Master Plans that emphasize nonstructural measures, increase opportunities to realize beneficial functions in floodplains and seek cost-effective solutions that minimize major construction efforts. Action Item: Evaluate the costs and resources required for updating mitigation master plans to increase a focus on cost-effective non-structural efforts. Attachment C 6 b) Reevaluate Priorities for Mitigation Efforts by: • Addressing bottlenecks (bridges, culverts and roads) at critical locations. ■ Acquiring floodplain lands to avoid channel improvements and eliminate hazardous uses. • Performing non-structural overbank grading to increase conveyance and flood storage. The 1992 Boulder Creek Project at Boulder High School involved acquisition and removal of 169 residential units in the high hazard zone and non-structural overbank grading north of Boulder Creek to create the current open recreational fields. The $3 million project also removed the Goss-Grove neighborhood from the high hazard zone by increasing conveyance near the creek and opened up the community-valued Boulder Creek greenway corridor. ■ Targeting limited flood protection improvements for specific locations and working on restricted drainageway reaches to eliminate high hazards zone conditions and satisfy multiple objectives. ■ Researching alternative mitigation approaches and improvements that may be completed for mid-stream reaches that don't require extensive downstream drainageway construction first to avoid adverse impacts from upstream modifications. Action Item: Evaluate the costs and resources required for updating mitigation master plans considering these policy objectives in conjunction with non-structural efforts. c) Carefully Consider the Need for Structural Improvements by adequately assessing the alternatives that may be applied to avoid and minimize structural improvements, such as flood proofing, acquisition and relocation, and obtaining or supplementing flood insurance. These alternatives may involve acquisition and removal of structures, possibly affecting and relocating residents. Relocation of residents is a sensitive matter and concern must always be considered for the emotional distress such activities may create. However, in some cases, acquisition and relocation of high hazard structures may offer greater long-term benefits, immediately eliminates the hazard to people and may be more cost-effective (thereby offering greater opportunities for relocation compensation) than constructing very structural and narrow channel improvements to avoid existing structures. Action Item: Implement planning guidelines to include analyses of non-structural alternatives as part of all floodplain mitigation planning and design activities. d) Focus on High Hazard Mitigation by primarily pursuing improvements in citywide locations that will reduce high hazard areas to the greatest extent possible. Action Item: Identify locations to consider floodplain mitigation where high hazard conditions exist and prioritize by locations subject to the greatest risk levels. e) Implement Mitigation Efforts Citywide to ensure that the most high-risk floodplain occupants are given priority and avoid putting all efforts into one or two drainage systems that consume significant funds for long periods. Action Item: As outlined above, identify locations to consider floodplain mitigation where high hazard conditions exist and prioritize by locations subject to the greatest risk levels. Attachment C 7 it APPENDIX D STORMWATER AND FLOOD MANAGEMENT UTILITY MASTER PLAN UPDATE BOULDER FLOODPLAIN PROPERTIES MAPPING July 11, 2002 The Boulder Floodplain Properties Mapping project was completed to assess the vulnerability of properties to floods that lie in and around the city of Boulder. A list of properties that would be affected by flooding was complied and several analyses were completed. The levels of flooding that were assessed were the FEMA 100-year and FEMA 500-year levels. In addition, the city 100-year flood plain was assessed along with the Shallow Zone, High Hazard Zone, and Conveyance Zone. This was compiled into a master list, which contained the property and information about the property used to evaluate the possible damage in the event of a flood. Several assumptions and notes that pertain to the project are as follows: 1. Shallow Zone, High Hazard Zone, and Conveyance Zone properties are included in City 100 and FEMA 100 Zones 2. Properties that were included in the study, not contained within the city limits are located within the boundary from the northernmost city limits to the southernmost city limits and from the westernmost city limits to 751h Street. These are the "county" properties. 3. ENCLAVE Properties are included in County Properties 4. County properties do not have a city zone associated with them in the MapLink GIS assessors database. In this case, they were considered in the "county" zone. 5. All properties assessed were in the FEMA 500-year flood plain. Therefore, the total amount values for each zone could be found in the FEMA 500 category. 6. The Boulder County assessor's data used to create the list was obtained from MapLink software last modified June 18, 2002. The results of the study were then tabulated and the major trends and points of interest are as follows: 1. In total, there are 6082 properties contained in the study covering 15055 acres. These properties are home to $1,414,277,100 in buildings. 2. Residential zoned properties contain the most property value and in most cases are nearly equal to the sum of the property value of the business and industrial zones. 3. The city of Boulder owns 321 parcels of land in the study area. These properties cover 7545 acres and contain buildings worth $16,754,900. 2 i a~a~a aco~ Off` ^oo~ hoo~~ .A~ o~ ate`°~ ~P Zone Information G Q~ 5r Q40 Number Properties with structures 648 840 2361 2650 143 3840 Residential Acres of flooded area 586 626 1002 1046 167 1383 Assessed Building Value $148,713,600 $165,545,200 $365,532,200 $420,119,300 $47,636,100 $619,441,200 Number Properties with structures 81 108 231 305 15 549 Business Acres of flooded area 212 244 346 478 85 526 Assessed Building Value $78,271,600 $91,618,700 $157,397,700 $210,457,100 $23,884,300 $310,188,500 Number Properties with structures 37 47 128 182 5 234 Industrial Acres of flooded area 225 260 441 900 46 1013 Assessed Building Value $47,347,400 $55,821,300 $164,467,500 $213,996,700 $12,314,900 $310,649,800 Number Properties with structures 1 0 2 2 0 2 Agricultural Acres of flooded area 17 15 40 40 0 40 Assessed Building Value $139,200 $0 $141,600 $141,600 $0 $141,600 Number Properties with structures 81 101 425 425 17 649 County Acres of flooded area 1547 1595 5192 2497 907 10586 Assessed Building Value $15,167,800 $17,318,800 $110,463,600 $106,766,800 $3,011,100 $134,410,100 Number Properties with structures 11 12 18 18 4 21 Public Acres of flooded area 1087 1100 1157 1460 716 1509 Assessed Building Value $19,467,800 $20,271,300 $37,215,300 $37,215,300 $15,287,100 $39,445,900 Number Properties with structures 859 1108 3165 3582 184 5295 Total Acres of flooded area 3674 3840 8179 6420 1922 15055 Assessed Building Value $309,107,400 $350,575,300 $835,217,900 $988,696,800 $102,133,500 $1,414,277,100