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200127 Commission Retreat Jacobs FINAL ocrndBlue-Green Infrastructure, Road Elevation Strategy and Neighborhood Project Prioritization January 27, 2020 Commission Resilience Workshop BI0909191410MIA Agenda •Task 1: Blue-Green Stormwater Infrastructure (BGSI)Concept Plan •Task 2: Road Elevation Strategy •Task 3: Neighborhood Project Prioritization •Public Meeting: Community Comments / Feedback •Questions & Discussion 2 BI0909191410MIA Project Leadership 3 Matt Alvarez Project Manager years 25 Juan F. Aceituno Deputy Project Manager/ Implementation Task Lead years 23 Laurens van der Tak Climate Adaptation Advisory Panel years 30 Jason Bird Planning Task Lead years 20 Joe Rozza Blue-Green & Sustainability years 25 Monica Diaz Public Outreach years 15 Task 1 Blue-Green Concept Plan BI0909191410MIA WHAT IS BGSI? •Green stormwater infrastructure typically uses vegetation and/or soils to treat and reduce stormwater flows •Blue stormwater infrastructure temporarily stores and treats stormwater •BGSI is typically designed and sized to capture more frequent storm events •Different from coastal strategies, such as living shorelines, dunes, mangrove plantings, and oyster or artificial reefs Rain Garden 5 BI0909191410MIA WHY SHOULD WE USE BGSI? •Stormwater benefits –Water quality (WQ) –Groundwater recharge –Some detention/flood mitigation •Community benefits –Urban heat island mitigation –Air quality –Climate resiliency –Ecosystem health/biodiversity Frost Museum of Science 6 BI0909191410MIA BY RECHARGING THE FRESHWATER LENS, BGSI CAN HELP KEEP SALT WATER AT BAY TO PROTECT OUR TREES Source: ULI Advisory Services Panel Report on Miami Beach, 2018 (adapted) Freshwater Lens 7 BI0909191410MIA HOW WILL BGSI FIT INTO THE CITY’S FLOOD MITIGATION STRATEGIES? •Complements “grey” infrastructure •Provides some detention/flood mitigation, but alone will provide little or no benefit for: –“sunny day” flooding –flooding from major rainfall –storm surge •Designed for storms 2 inches or less, which is about 25% of the much larger storms typically used for flood control Flooding on May 16, 2019 8 BI0909191410MIA COMMUNITY (CO-BENEFITS) OF BGSI Source: Potential Environmental, Social, Economic, and Public Health Benefits of Green Infrastructure by U.S. Environmental Protection Agency (2017) 9 BI0909191410MIA WHAT BGSI PRACTICES ARE MOST APPLICABLE TO MIAMI BEACH? •Permeable Pavement •Rainwater Harvesting (Cisterns, Rain Barrels) •Stormwater Planters •Subsurface Infiltration/Storage •Tree Canopy •Wet Ponds •Bioretention/Bioswales/Rain Gardens •Blue and Green Roofs •Constructed Wetlands/Floating Wetland Islands •Detention Basins/Surface Storage •Enhanced Tree Pits/Trenches •Low Volume Injection Wells (Pumped) Note: The City is developing an Urban Forestry Master Plan. 10 BI0909191410MIA WHAT DOES BGSI LOOK LIKE? •Takes many different forms, from landscaping elements to permeable pavements to ponds to green roofs •Can vary greatly in appearance, from high-profile features to those that blend in •Vegetation requires time to get established Bioretention 11 BI0909191410MIA Examples of BGSI Applications •Pervious concrete parking lot •Green roofs •Blue-Green Roof Plaza •Permeable Paver Driveway 12 BI0909191410MIA WHERE CAN BGSI BE USED? •In a variety of locations: –Roads –Parks and other open spaces –Schools/public facilities –On rooftops –Residential and commercial properties •Miami Beach is approximately 40% impervious area •Goal is to preserve and increase pervious (“green”) area Roads 13 BI0909191410MIA Parks 14 RENDERING OF NEIGHBORHOOD BI0909191410MIA Note: all concepts are preliminary and subject to change during budgeting, design, permitting, etc. RENDERING OF PAR 3 COMMUNITY PARK POND 15 BI0909191410MIA COLLINS CANAL 16 BI0909191410MIA COMMERCIAL STREET 17 BI0909191410MIA RESIDENTIAL STREET 18 BI0909191410MIA NEIGHBORHOOD PARK 19 BI0909191410MIA Concept Plan & Fact Sheets Task 2 Road Elevation Strategy ATLANTIC OCEAN INDIAN CREEK BISCAYNE BAY »Tidal flooding can occur on sunny days: ─Through storm drains ─Through groundwater ─Exacerbated with SLR Flooding in Miami Beach, like all coastal cities, can come from 3 different sources, separately or together. ATLANTIC OCEAN INDIAN CREEK BISCAYNE BAY »Tidal flooding: ─Through storm drains ─Through groundwater ─Exacerbated with SLR »Rainfall flooding Flooding in Miami Beach, like all coastal cities, can come from 3 different sources, separately or together. 24 ATLANTIC OCEANINDIAN CREEKBISCAYNE BAY »Tidal flooding: ─Through storm drains ─Through groundwater ─Exacerbated with SLR »Rainfall flooding »Storm surge from tropical storms (driven by wind/ barometric pressure) Flooding in Miami Beach, like all coastal cities, can come from 3 different sources, separately or together. BI0909191410MIA ATLANTIC OCEANINDIAN CREEK BISCAYNE BAY Raising roads is an important strategy to address sunny day tidal flooding in public right-of-way •Through storm drains •Through groundwater •Through overtopping of coastal barriers (e.g., seawalls) •Exacerbated by Sea Level Rise (SLR) BI0909191410MIA Backflow Seepage Tidal flooding is problematic in low-lying areas BI0909191410MIA Drainage Tidal Flooding increased with Rainfall BI0909191410MIA Long Term Strategy includes Elevated Roads, Sea Walls and Pumps BI0909191410MIA Road Raising Strategy Addresses Tidal Flooding Only 29 Complete Property Flooding (12+ inches) Partial Property Flooding (6−12 inches) Street Flooding (0−6 inches) High tide with 3 ft of sea level rise City Policy: Road storm drainage systems are designed for storm capacity of up to 10-year 24-hour storm: 8.25” storm. Storms with higher volume and intensity may cause flooding of both roads and adjacent property, regardless of whether road is raised. 30 31 BI0909191410MIA Guiding Principles of New Road Raising Strategy •Support keeping road surfaces above the king tide elevation to avoid sunny day tidal flooding •Establish new minimum elevations for City roads based on updated tidal records and SLR projections •Address increasing groundwater elevations and concern for poor pavement performance, including premature pavement failure related to saturated road base •Address concern for private property harmonization •Standardize application so policy is unbiased, objective, and transparent •Consider cost implications 32 BI0909191410MIA Summary of Key Factors that Determine Minimum Road Elevation Criteria •Evaluates elevations at edge of road (EOR), not crown, and at bottom of road base (BORB), and picks the most protective standard •Assumes 30-year road service life •Updated Sea Level Rise projections •Target frequency of flooding (applies at end of road service life): •Local Roads: 50% chance per year (includes roads classified by City as “Local”, mostly residential roads) •Major Roads: 20% chance per year (includes roads such as Washington Ave. classified as “Minor Arterial” and “Minor Collector”) •Emergency Roads: 10% chance per year (includes roads such as Alton Rd. classified as “Evacuation Route and access to First Responders) 33 BI0909191410MIA Updated decision process calculates minimum road elevations at two points on road section 34 BI0909191410MIA Calculation Method 1 – Step 1: Select Level of Service (% chance of flooding by road type) 35 Measured Tides (1994-2019) at Virginia Key (ft NAVD) Ti d e a n d S e a L e v e l ( f t NA V D ) Long-Term Water Surface Elevation Data at Virginia Key (25 years of hourly data) is used to estimate probability of water elevations being exceeded. BI0909191410MIA Calculation Method 1 – Step 2: Determine Water Elevations for Selected Level of Service 36 Water Surface Elevation at Virginia Key (ft NAVD) Wa t e r S u r f a c e E l e v a t i o n ( f t NA V D ) Annual Exceedance Probability 2.34 ft water elevation has 20% chance of being exceeded in any year (on average, once every 5 years). BI0909191410MIA Calculation Method 1 – Step 3: Determine Sea Level Rise for Each Type of Road 37 Relative Sea Level Rise for Miami Beach (NOAA*, 2017) RS L R (f t NA V D ) 30-yr service life of road SLR of 1.3 ft or 1.8 ft 30 years out from 2020, for NOAA Int-High or High Curves *NOAA = National Oceanic and Atmospheric Administration BI0909191410MIA 38 Recommended SLR projections are consistent with SE FL Climate Compact (3rd Regionally Unified Sea Level Rise Projection 2019): •NOAA Intermediate High for Major and Local Roads •NOAA High for Emergency Roads Calculation Method 1 – Step 3: Determine Sea Level Rise for Each Type of Road BI0909191410MIA Calculation Method 1: Goal of Limited Flooding at Edge of Road (EOR) results in EOR Minimum Elevation of 3.0 ft to 4.8 ft NAVD 39 BI0909191410MIA Calculation Method 2: Limited Groundwater Wetting at Road Base during High Tide (MHHW) Results in Bottom of Road Base (BORB) Minimum Elevation of 2.9 ft NAVD 40 NOAA Published MHHW of 0.2 ft NAVD for 1983-2001 epoch was updated to 0.6 ft NAVD based on recent tidal data. BI0909191410MIA Higher of two calculation methods is selected for EOR or BORB 41 BI0909191410MIA All Roads ̶Minimum Elevation of Bottom of Road Base (Method 2): 2.9 ft, so Edge of Road is 3.9 ft assuming 1-ft road thickness 42 Method 2 is used to set Minimum Elevation of Bottom of Road Base: 2.9 ft NAVD for projects built in 2020. BI0909191410MIA Major and Local Roads ̶Method 1 is lower (3.6 ft and 3.0 ft NAVD), so Method 2 is Preferred: Bottom of Road Base, > 2.9 ft and EOR > 3.9 ft NAVD 43 For Local Roads, Method 2 results in higher Minimum Elevation at Edge of Road, assuming projects with 1-ft road thickness and built in 2020. Method 1: Limited Flooding at EOR Method 2: Limited Groundwater/Tidal Wetting at BORB BI0909191410MIA Emergency Roads ̶Minimum Elevation at Edge of Road (Method 1): 4.8 ft NAVD 44 For Emergency Roads, Method 1 results in higher Minimum Elevation at Edge of Road for projects built in 2020. BI0909191410MIA Project Start Date 2020 2025 2030 2035 2040 Emergency Roads (Method 1)4.8 5.2 5.7 6.2 6.7 Arterial and Local Roads (Method 2) *3.9 4.2 4.5 4.9 5.3 * Method 2 assumes 1 ft road thickness above bottom of road base. 45 Relative Sea Level Rise for Miami Beach (NOAA, 2017) RS L R (f t ( NA V D ) SLR of 2.7 ft or 1.9 ft 30 years out from 2030 30-yr from 2030 30-yr from 2040 30-yr from 2020 SLR of 3.7 ft or 2.7 ft 30 years out from 2040 SLR of 1.8 ft or 1.3 ft 30 years out from 2020 Road raising strategy for future projects increases in recognition of accelerating Sea Level Rise projections BI0909191410MIA Road raising projects can be prioritized based on current risk of tidal flooding Road Miles by Type and Current Probability of Tidal Flooding Road Lengths by Classification and Elevation 50% chance of flooding today 20% chance of flooding today 10% chance of flooding today > 10% chanceCurrent Chance of Tidal Flooding Today → Principal Arterial ("Emergency")0.5 1.4 4.1 19.5 Minor Arterial ("Major Road")1 4 4.1 4.5 Major Collector ("Emergency")0.5 2.5 6.3 12.8 Minor Collector ("Major Road")0.2 2.2 3.3 2.7 Local ("Local Road")6 22 31 55 Total 8.2 32.1 48.8 94.5 46 BI0909191410MIA After receiving public input this road raising policy was applied which shows areas with various road raising needs Applying this policy can be used to define new road raising projects and sequencing for neighborhoods to increase resiliency 47 These results will be used to establish project groupings and priorities Example BI0909191410MIA Harmonization with Adjacent Property •If constraints are identified by the City Engineer, as a result of the minimum road elevation, then harmonization exception criteria supersede, at the discretion of the City Engineer. •Example exception criteria may include: •Inadequate horizontal space to construct road improvements and tie back to existing grade •Driveway grades and grade break cannot meet City standards at new elevation, posing access concerns •Adverse stormwater management conditions created 48 BI0909191410MIA Harmonization with Adjacent Commercial Property •Existing issue (saturated base causing road system failures) •Proposed road elevation creates conflicts with buildings •Harmonization solution includes use of edge treatment to mitigate 49 BI0909191410MIA Harmonization with Adjacent Residential Property •Proposed road elevation may create driveway access issues. •Shift sidewalks to decrease angle of slope. •Raising sidewalk and roadway less to decrease angle of slope. 50 BI0909191410MIA Proposed Criteria for Harmonization •Driveway slopes within FDOT standards to avoid adverse conditions. •Recommended maximum driveway slopes •Residential:12.5%(1V:8H) •Commercial: 10.0%(1V:10H) •Recommended max. sidewalk cross-slope = 1.5% 51 Adverse Driveway Conditions BI0909191410MIA Proposed Criteria for Harmonization What do driveway slopes mean for road raising? •Recommended maximum driveway slopes •Residential:12.5%(1L:8H) •For example, if you have a 20 ft long driveway, the road can’t be raised more than 2.5 ft without some harmonization. 52 Illustrative example L = Driveway Length If driveway length L = 20 ft, then road raising can’t be more than H = 20/8 = 2.5 ft (12.5% slope) BI0909191410MIA Proposed Criteria for Harmonization If driveway slope changes more than 14.0% at a crest or sag, a vertical transition will be provided. 53 •Rounded vertical transitions •Straight vertical transitions Adverse Driveway Conditions Rounded Vertical Transitions Straight Vertical Transitions BI0909191410MIA Proposed Harmonization Solutions (Examples) •Alternative road treatments (retaining walls, steps, ADA ramps, etc.) •Temporary construction easement to reduce slope of driveways. •Lower sidewalk at driveway to improve driveway grades. •Collect stormwater from behind sidewalk, into storm drainage system. •Don’t raise roadway as high as minimum standard. (solutions vary between residential and commercial property) 54 Task 3 Neighborhood Project Prioritization BI0909191410MIA Neighborhood Project Group Prioritization Objectives •Strategically guide prioritization of City Neighborhood Projects •Maximize benefits, minimize impacts •Objective, transparent, and repeatable methodology NEIGHBORHOOD PROJECT: A project involving multiple City Services; for example: •Road improvements •Water/sewer maintenance •Stormwater upgrades City Planning Processes Individual Capital Projects Group into Prioritized Neighborhood Projects Prioritization Methodology Overall Process for Neighborhood Project Prioritization Today’s Focus BI0909191410MIA Guiding Principles •Public safety is top priority •Water and wastewater service delivery and environmental protection support multiple objectives •Public health, local economy, regulatory compliance •Economic development is supported by City services •Service delivery/capacity, risk management •Routine maintenance supports long-term service supply reliability •Aesthetics not a stand-alone objective (but important) 57 BI0909191410MIA Neighborhood Project Prioritization •Development of Methodology •11 project component categories; each with 5 criteria corresponding to level of importance •Developed weight factors for each category •Notes About Methodology •Project components can have attributes that span multiple categories •Project components with multiple benefits produce higher scores 58 BI0909191410MIA Prioritization: Eleven Categories of Project Components 59 Project Component Categories Objectives and Benefits of City Projects Brief Description Aesthetics Landscaping, historical integrity, green streets Coastal Flood Risk Management Exposure and sensitivity to king tides, sea level rise, storm surge, extreme weather Economic Development Support Tourism, Historic Preservation Emergency (Critical) Facilities and Roads Emergency response effectiveness Environmental Benefits (Ecological)Protect the Bay, Heat Island, Habitat, Adaptation Pedestrian and Bicycle Mobility Infrastructure that enables more and safer pedestrian and bicycle movement Potable Water/Fire Suppression System Public safety, public health, and infrastructure condition Rain Driven Storm Water Management Flood management, environmental protection, and regulatory compliance Road Classification Type and capacity of road Sanitary Sewer Service Delivery Provision of service, capacity and condition of system Transportation –Road Condition/Remaining Service Life Condition and service life of road BI0909191410MIA Neighborhood Prioritization Rating Project Components Across Multiple Categories of Objectives and Benefits 60 BI0909191410MIA Neighborhood Prioritization Rating Project Components Across Multiple Categories of Objectives and Benefits 61 Rank Project Category Project Category Weight Factor (%) 1 Coastal Flood Risk Management 100 2 Potable Water Distribution / Fire Suppression System 100 3 Emergency (Critical) Facilities & Roads 90 4 Sanitary Sewer Service Delivery 85 5 Rain Driven Storm Water Management 85 6 Environmental Benefits 70 7 Economic Development 60 8 Pedestrian and Bicycle Mobility 50 9 Road Classification 40 10 Road Condition Maintenance 40 11 Aesthetics 35 BI0909191410MIA Neighborhood Project Group 1 (Example) 62 BI0909191410MIA Neighborhood Project Group 2 (Example) 63 BI0909191410MIA Neighborhood Project Group 3 (Example) 64 BI0909191410MIA Example: Ranking and Prioritizing Neighborhood Projects Groups 65 Highest Priority Project BI0909191410MIA After Receiving Public Input Project Component Criteria Were Applied •Reviewed and scored project components from City planning documents; •Water & Sewer Utility Master Plan •Stormwater Master Plan •Active Capital Improvement Program •GO Bond •Transportation Master Plan •Highly driven by the number, benefit and type of project components currently in the planning pipeline •Road Raising Projects using the new policy will be added to prioritization after development 66 First Draft BI0909191410MIA 67 First Draft Public Meeting: Community Comments / Feedback BI0909191410MIA Tasks 1 : Public Meeting Comments / Questions •Residents Major Themes: •Neighborhood Outreach •Policy for Private Property Implementation (incentives) •Heat Island Effect / Tree Canopy •Who will maintain BGSI? •Resiliency (Saltwater Intrusion, Storm Surge, SLR, Cloudburst Events) 69 BI0909191410MIA Tasks 1 : Public Meeting Comments / Questions •Residents Major Themes: •How will BGSI function with high groundwater, as sea level rises? •Integration with Road Raising and Flood Protection •Educational Opportunities •Implementation Cost •Aesthetics 70 BI0909191410MIA Tasks 2 & 3: Public Meeting Comments / Questions •Residents Major Themes: •Fear of raising roads resulting in property flooding •Evaluate ranking priorities based on neighborhood risks •Prioritize flood protection of properties over streets •Sea level rise projections •Consideration of seawall •Impact of road raising policy to ongoing / on-hold projects •Consider a higher priority to aesthetics •Water quality /environmental impacts •Community outreach by neighborhood •Frequently Asked Questions (FAQ) Handout 71 BI0909191410MIA Comments After the Task 2 & 3 Meeting •Comment period was open through January 24, 2020 •Received 12 emails with comments •Major themes: •Creating flooding where none exists •Keeping streets dry at the detriment of private property •Wet homes with dry streets •Aging underground infrastructure 72 BI0909191410MIA Tasks 2 & 3: Public Meeting Comments / Questions “I fully support their efforts to follow the science and address that significant issues that we as a community will face if actions are not taken…”. –Lakeview Resident “We feel that Jacobs should be applauded for recognizing that certain roads can flood more, some less often, for safety reasons rather than use a one- size-fits-all approach. Candidly though, we do need more focus on filtration of storm water prior to being discharged into Biscayne Bay, and a more robust discussion of necessary upgrades to our water, sewer and storm water infrastructure.” –Lakeview Resident 73 “I have lived in Sunset Harbour for 20 years and thank the City every day for having raised our streets. Since the streets were raised, we have not had flooding, our buildings garages have not flooded and our streets are passable when it rains, when the tides are high and during the several hurricanes that we have had.” – Sunset Harbour Resident “I commend you all for being proactive. And I commend you for putting the time, energy and brainpower in to figuring out how to do this right -and please understand that those of us questioning the existing strategy are not climate change deniers, nor are we resistant to change.” –South Beach Resident Questions & Discussion