Context

The greenway follows a discontinued rail corridor along an industrial edge of north Denver. Aesthetic elements such as custom-built shade structures, benches and design details all echo this historic use in a way that celebrates the connectivity that rail brought. Because the corridor covers a lot of distance, native plantings and a natural seed mix were utilized as the most effective and maintainable palate. Over 500 trees were planted and another 2-3 times that in shrubs to revegetate and restore the rail scar. Public art was selected in key areas, with central art elements along the path, and an art piece that acts as a gateway at Steele Street. The landscape architect also developed 11 interpretive signs that highlight the area’s history and natural systems.

Special Factors

Interdepartmental + Interdisciplinary Approach:

As a design-build project, the landscape architect was heavily integrated into all steps of the process and worked closely with engineers, contractors, and many different departments within the City and County of Denver. The project involved staff from Public Works, Capital Projects, Parks and Recreation, Forestry, Green Infrastructure, Storm Water and Water Quality. The storm water management features tie in with neighboring infrastructure to provide 100-year flood protection to the Cole and Clayton neighborhoods. Multiple open houses and stakeholder meetings were held throughout the project, with continuous online updates made to the City’s website. A Design Working Group, made up of representatives from the community, was continuously engaged as advocates and local champions for the project. The project team developed an early animation that was updated throughout the project to communicate with the public and between each department: https://www.youtube.com/watch?time_continue=24&v=tgqrIl89PqI

Multimodal Design: Denver’s First Shared Street

To create a flexible space for pedestrians, cars and other programming, the project activated the space, calmed traffic and allowed for flexible use throughout the year. Denver’s first shared street between Franklin Street and Williams Street was developed to implicitly slow traffic, and also allow for easy loading and unloading of delivery vehicles. Designed on a single plane, with no curbs or gutters, it is defined by zones that include multi-modal, amenity, and pedestrian all acting as part of a continuous street/plaza. Areas of use are designated by textures and colors, with buffers provided by benches, bollards, planters and furnishings. The vehicle right-of-way meanders, instead of taking a straight line, which helps calm traffic. By removing the formal distinctions that divide users into pedestrians, cyclists, and vehicles, the street is truly shared, with each user increasingly aware and respectful of the others. The flexible space means mobility is less impacted during events that would have otherwise necessitated street closures.

Social Equity and Inclusive Public Outreach

As one of Denver’s historically blue-collar neighborhoods, this community supported the growing industry of the city, including railroads, meat packing and smelting. As those industries declined or moved out, these neighborhoods felt the loss. Today, it is home to a growing urban business district called River North, and is experiencing an upswing in development and revitalization. This vitality has brought to light the infrastructure problems that have long plagued the neighborhood’s homes and businesses.

Nine community meetings were held so residents could provide ideas on what they would like to see for amenities, as well as solutions to managing storm water runoff. The outreach process also included Denver schools, staff, and students whose facilities back up to the greenway providing a great opportunity for outdoor learning spaces. Input from local businesses was important to ensure that they had access, parking, and the opportunity to take advantage of the new greenway and its recreational amenities.

Environmental Sensitivity and Sustainability

One of the most important elements of this project are the stormwater management facilities. The project connects with neighboring infrastructure to provide 100-year flood protection. The landscape architect worked with the civil engineer to provide water diversion, detention and water quality features such as permeable landscaping, street-side planters for capturing runoff, forebays for sediment and trash collection and a natural, open channel for collection and diversion of stormwater flows.

Hazardous Substances

A Subsurface Investigation Report was completed that identified low-level arsenic concentrations that exceed CDPHE guidance levels. The operation of three smelting plants, presence of two historical urban infills, and the presence of a historical railroad and other light industrial activities within the project limits were also of concern. With this information, the contractor was required to identify potential Hazardous Substances through observation as Approved in the Materials Management Plan developed for the project. The City was responsible for testing and remediation as necessary, including the removal of known contamination and underground storage tanks.

Stormwater Treatment/Water Quality

The drainage and water quality work generally consisted of stormwater conveyance and water quality improvements within the open channel with pipe connections to regional basins and within the surrounding neighborhoods. It is a closed system that connects and outfalls into the Globeville Landing Outfall infrastructure. An open channel was also graded along 39th Avenue and the abandoned Burlington Northern Santa Fe railway from Franklin Street to Steele Street to capture the 100-year stormwater runoff event. The Greenway incorporated landscaping, amenities, recreation, and aesthetic elements that were presented to the public for feedback and inclusion in what was to be included in the greenway. Through storm drains and associated structures, water flow was captured and conveyed into the open channel. Additional connecting systems helped to maintain depths of flow in the roadways per City standards and intercepts all surface and piped flows prior to entering the nearby lightrail station. All roadway improvements incorporate drainage and water quality facilities that meet the requirements of the MS4 permit and incorporate green infrastructure solutions for capturing and treatment of storm water that include urban streetside stormwater planters, pervious landscape elements, pervious pavers, trash vaults and vegetated swales.

Significance

Like many large cities across the west, Denver’s historic neighborhoods face significant aging and infrastructure gaps. The 39th Avenue project demonstrates how landscape architecture supports urban design to meet multiple goals at once: recreation, stormwater conveyance, green infrastructure, multi-modal transportation enhancements and ultimately the economic development of an underserved neighborhood. The team worked together within sensitive constraints to design long-term solutions that are already a catalyst for change, bringing vitality and a greater sense of pride from its residents. New and resurfaced streets provide better business access and the owners are reinvesting in their businesses to take advantage of the new amenity that runs right past their door. Most importantly are the much-needed improvements for mobility and connectivity. With new connections, critical public transportation amenities, and trail connectivity, the project provides safe regional access and completes a missing connection to the South Platte Trail. With improved lighting and accessibility, residents have safer routes to work, home and school, and an easier way to get around the community.

The 39th Avenue Greenway project began with the idea of creating a local amenity that provides storm water conveyance combined with a recreational feature that would enhance the neighborhood. Through collaboration with the client, stakeholders, contractors, and the community, it became a case study in how important it is to approach these projects from an interdisciplinary lens and involve the people who will gain and be impacted the most.