Marion Street Green Infrastructure Project. Whittier Neighborhood Community Meeting April 18, 2018

Transcription

1 Marion Street Green Infrastructure Project Whittier Neighborhood Community Meeting April 18, 2018

2 Agenda Water quality and green infrastructure Overview: Marion Street stormwater project Green infrastructure opportunity Overview Table exercise: Getting to know Marion St

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4 The Problem Over 1200 Total Outfalls 300+ Outfalls into Cherry Creek 300+ Outfalls into South Platte 13% of Denver s 98,900+ acres receive water quality treatment 2013 Matrix Report Denver s Streams: 0/10 meet recreation standards 7/10 suitable for aquatic life 2016 Water Quality Report, Denver Dept. of Environmental Health

5 Addressing These Challenges Grey Infrastructure Community Strategic Green Engagement Planning Infrastructure

6 Green Infrastructure Natural or built systems that use vegetation and soils to manage stormwater runoff More resilient approach than relying on gray alone Numerous benefits Varying scales

7 Benefits of Green Infrastructure Improve water quality Reduce flood risks Reduce Urban Heat Island effect Improve air quality Absorb local carbon emissions Improve public health outcomes Increase physical activity Improve mental wellbeing Reduce stress Lower traffic speeds and reduce injury crashes Improve property values

8 Sub/Regional Scale Green Infrastructure Site-Scale Green Infrastructure

9 Current Projects 33 rd Street Outfall Brighton Boulevard Hampden Heights Carla Madison Recreation Center 21 st and Broadway

10 Denver s Residential Green Infrastructure Lowell and Evans 16t Street (Upper Montclair Basin)

11 Green Infrastructure and Health 2017 Denver Department of Public Health and Environment produced white paper about green infrastructure and potential health risks. Key findings: Concern Organic Compound Heavy Metals Bacteria and Human Pathogens Nitrogen and Phosphorous Disease Carrying Vectors Finding Low levels, not a concern to public health (compared to EPA health risk guidelines) Low levels, not a concern to public health (compared to EPA health risk guidelines) Public health risk no greater than exposure to other sediments and soils Nitrogen generally not retained in sediments; phosphorous generally in insoluble, mineralized form Facilities are designed to drain quickly in order to eliminate or minimize mosquito habitat For full copy of white paper, please waterquality@denvergov.org

12 Maintenance Soft Trash collection and sediment removal: City Maintenance Contract Vegetation: City Maintenance Contract BID/MID Neighborhood Stewards Hard = Concrete and pipe structures Denver Public Works

13 STORM DRAIN IMPROVEMENTS THE BIG PICTURE The 33 rd Street Outfall and the Marion Street System are key components for upgrading the level of drainage service within the neighborhoods of Five Points, Cole, Whittier, and City Park West. The new storm drain system will improve drainage during a fiveyear storm event and address areas where significant flooding could occur

14 33 RD STREET OUTFALL PROJECT Three of the four segments have already been constructed. Construction for the fourth and final segment, which runs from Curtis Street to Marion Street just south of Martin Luther King Jr Boulevard, is anticipated to begin in the summer of 2018

15 33 RD STREET OUTFALL STRUCTURE The new outfall structure at the South Platte River was designed to connect to the river overbank rather than to the river itself, facilitating stormwater treatment prior to entering the river

16 STORM DRAIN CAPACITY EXISTING VS. PROPOSED The new storm drain in 33rd Street is approximately 28 times larger than the existing 24"-diameter storm drain

17 33 RD STREET OUTFALL NEW STORM DRAIN A photo of the 33rd Street Outfall System under construction - note the shovel and broom inside the pipe, and the workers standing above

18 FLO-2D ANALYSIS (EXISTING CONDITIONS) A model of the estimated maximum flow depths for the 100-year storm (that is, on average, one would expect a storm of this intensity or greater to occur only once in 100 years) prior to the construction of the 33 rd Street Outfall

19 FLO-2D ANALYSIS (PROPOSED CONDITIONS) A model of the estimated maximum flow depths for the 100-year storm (that is, on average, one would expect a storm of this intensity or greater to occur only once in 100 years) after the construction of the 33 rd Street Outfall

20 100-YEAR STORM DEPTH REDUCTIONS The 33rd Street Outfall System will alleviate (relatively) frequent flooding problems in the Five Points/Whittier/Cole neighborhoods; however, benefits can also be expected for larger, less frequent storms, as well. Note the depth reductions in the figure to the right for the 100-year storm (that is, on average, one would expect a storm of this intensity or greater to occur only once in 100 years)

21 33 RD STREET OUTFALL PROJECT ADDITIONAL INFORMATION Visit the City s website to view overall project status, photos, videos, and to sign up for project updates. Simply type Denver 33 rd Street Outfall in your search engine of choice, or search for the project at

22 MARION STREET SYSTEM The Marion Street System is a key component for upgrading the level of drainage service within the Whittier neighborhood (projects "A" and B" in the master plan map, right). The new pipe in Marion Street will intercept storm drain laterals to the east (21st through 31st Avenues), and will form a "dual system" with the existing storm drain in Downing Street that will continue to convey runoff from nearly all of the City Park West and Cheesman Park neighborhoods

23 PHASES, SCHEDULE & IMPACTS The project will be split in two phases - from Martin Luther King Jr Boulevard to 26th Avenue (Phase I) and from 26th Avenue to the 21st Avenue and Downing Street intersection (Phase II) Phase I is anticipated to begin in summer 2019; Phase II in the early part of 2020 General neighborhood impacts include temporary street closures with loss of on-street parking, one block at a time

24 SURFACE DRAINAGE IMPROVEMENTS Drainage conditions at each intersection along the Marion Street corridor will be significantly improved. For instance, new drainage inlets will be placed upstream of pedestrian curb ramps, as shown in this excerpt from the City's Storm Drainage Design & Technical Criteria Manual

25 STORM DRAIN CAPACITY EXISTING VS. PROPOSED By retaining the existing storm drain in Downing Street and constructing a parallel storm drain in Marion Street, the capacity of the drainage system will increase fourfold, as illustrated here

26 Opportunity: Green Infrastructure on Marion Street Implement GI on Marion Street as part of pipe project Cost-efficient

27 Activity: What does Marion look like? Residents interested in green infrastructure Phase 1: Intersection patterns MLK to 26 th Street Parking needs Other issues in the neighborhood