STORMWATER QUALITY MARION STREET GREEN INFRASTRUCTURE PROJECT COMMON SOURCES OF URBAN POLLUTANTS URBAN STORMWATER

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1 STORMWATER QUALITY COMMON SOURCES OF URBAN POLLUTANTS Fertilizers Litter Pet-waste COMMON POLLUTANTS FOUND IN URBAN STORMWATER BACTERIA TRASH METALS Dumpsters Vehicle exhaust, automotive fluids, etc. IMPACTS OF POLLUTED STORMWATER NUTRIENTS PUBLIC HEALTH: E.coli levels in Denver s streams and river often exceed swimmable beach standards set by the EPA. ENVIRONMENT: Water quality in most of the streams in Denver is not sufficient to support a healthy and diverse population of aquatic wildlife. OTHER WHY ADDRESS WATER QUALITY WITH GREEN INFRASTRUCTURE? ECONOMIC Cost effective approach to stormwater management that meets multiple goals Increased property values Increased building efficiency and reduced energy costs ENVIRONMENT QUALITY OF LIFE Healthier South Platte River, streams, gulches and lakes Improved aquatic and terrestrial habitat Better air quality Reduced urban heat island effect Increased resiliency Denver s neighborhoods Enhanced recreational corridors Healthier, greener neighborhood connections Educational opportunities

2 GREEN INFRASTRUCTURE Green infrastructure plays an important role in providing treatment to stormwater runoff before it is conveyed to our streams and rivers. By directing stormwater runoff through a vegetated green infrastructure facility, pollutants are removed as stormwater filters through plant material and soil. Without green infrastructure, most stormwater runoff is conveyed directly from the surface of our roads to the pipes in our storm drainage system which release directly into our streams and rivers, carrying with it pollutants and debris. Green Infrastructure (GI) is currently included in planning efforts across the City. Benefits of GI include: improved water quality peak flow reduction place-making high-quality environments for pedestrian and cyclists additional green space lower local temperatures improved air quality POTENTIAL GREEN INFRASTRUCTURE ALONG EXAMPLE OF POTENTIAL FACILITIES ON WITH GREEN INFRASTRUCTURE EXISTING Facilities located in spaces that minimize impact to existing mature trees and can add trees where trees do not currently exist EXAMPLES FROM OTHER CITIES Planters in tree lawn/existing rightof-way End-of-block curb extensions: minimize impact to parking create safer crossings for pedestrians

3 GREEN INFRASTRUCTURE & TRAFFIC CALMING MARION/25TH SYSTEM The Marion Street system is a key component for upgrading the level of drainage service within the Wittier neighborhood (Projects A & B in the Master Plan map, left). The new pipe in Marion Street will intercept storm drain laterals to the east (21st through 31st Avenues), and will convey runoff from nearly all of the City Park West and Cheesman Park neighborhoods. A STORM DRAIN CAPACITY - EXISTING VS. PROPOSED With the construction of the new storm drain in Marion Street, the capacity of the drainage system will increase threefold, as illustrated above. B SURFACE DRAINAGE IMPROVEMENTS In order to prevent standing water at the base of curb ramps, drainage inlets are typically placed upstream of the ramps. A number of the curb ramps along Marion Street have existing inlets downstream of the ramps, similar to the conditions shown in photo A above. Photo B above shows the same intersection with new inlets placed upstream of the ramps. 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 fall 2019; Phase II in summer 2020 More information regarding construction schedule and impacts to occur after the selection of a contractor (Summer 2019)

4 GREEN INFRASTRUCTURE MARION/30TH & MARION/29TH VIEW A VIEW B Conceptual Green Infrastructure - Marion Street & 30th Avenue (Plan View) Existing Conditions Aerial Image (Source: Google Earth) Conceptual Green Infrastructure - Marion Street & 29th Avenue (Plan View) GREEN INFRASTRUCTURE ON Based on feedback from the previous public engagement meetings with neighborhood residents, two intersections along Marion Street - at 30th and 29th Avenues - have been selected to receive the proposed green infrastructure. View A - Marion Street & 30th Avenue Green Infrastructure Concept View B - Marion Street & 30th Avenue Green Infrastructure Concept

5 GREEN INFRASTRUCTURE & TRAFFIC CALMING MARION/25TH Conceptual Traffi c Calming Marion Street & 25th Avenue (Bulb Out Option) Conceptual Traffi c Calming Marion Street & 25th Avenue (Median Option) & 25TH AVENUE TRAFFIC CALMING In addition to the green infrastructure planned at the intersections of Marion Street and 30th & 29th Avenues, a hybrid strategy of traffic calming and green infrastructure is presently being explored at the intersection of Marion Street and 25th avenue (north side of Whittier K-8 school). Feedback from both the residents and school representatives is sought for the two concepts depicted hereon.