Hood Bike Park: Pollution Purging Plants

2022 BSLA Professional Honor Award Recipient!

Context: A Catalyst for Adaptive Industrial Reuse

Hood Bike Park was crafted as a catalyst for change with a threefold vision:

1. Spur the redevelopment of 50+ acres of underutilized industrial land with a new open space for both future and existing community members. Charlestown residents have the least amount of open space per capita of any Boston neighborhood, and this new park helps offset that discrepancy. Hood Park is less than two miles from downtown Boston and within walking distance of the Sullivan Square regional transit hub, an ideal place to locate a new mixed-use district that will encourage economic growth.
2. Encourage green commuting for the neighborhood by providing bike facilities connected to a planned cycling network that links to the regional transit station.
3. Improve the quality of soil, groundwater, and stormwater by reducing residual contaminants from the former Hood Milk plant and to mitigate air pollution from interstate 93 which runs along the west boundary of the site. The pollutants impact the health of the Charlestown neighborhood; novel phytoremediation plant communities were selected to mitigate long-term effects.

The Warped Plane: Program, Form & Identity

A bike pavilion is integrated into a tilted landscape creating both a commuter amenity and a new flexible outdoor performance space. In Charlestown, there are few outdoor places for events. The sloped lawn provides seating for a stage and doubles as a new passive green. A roof deck with movable site furnishings creates an amenity for workers and residents of adjacent buildings. The elements are wound together with a ramped, universally accessible path. A monumental stair sits on axis with the remnant Hood industrial smokestack, creating a strong connection between the new community space and this iconic Boston landmark.

The pavilion offers bike storage and rentals, showers, gender-neutral public restrooms, and bike repair services that will encourage commuters to shift away from vehicular transportation and utilize a climate-positive alternative. The bike hub is strategically connected to a proposed regional bicycle trail network linking to the MBTA Sullivan Square station and downtown Boston.

The multifunctional topography helps to block views of the elevated highway to the west, raises the entire site above the anticipated coastal base flood elevation in 2100, and caps industrial soils in situ.

To amplify the sense of place, precast concrete stairs that transform into curbs and benches were inspired by the form of the original Hood Milk bottle. Hood was the first milkman in town to deliver individually packaged milk in bottles, eliminating disease pathogens. The double radius on the original bottle inspired the curved boomerang forms in both the plan and morphing site amenities. The night lighting amplifies these forms, with a streak of light winding up the topography and pin lights delineate transitions and make visible the curved forms at night.

Public Health & Phytoremediation Plant Communities

Utilizing three phytoremediation planting typologies, the project mitigates public health hazards posed by the site’s industrial history and adjacent highway.

• PHYTO Groundwater Buffer: Comprised of deep-rooted Populus spp., native Salix spp. and other water-seeking shrubs, the plants intercept and cleanse shallow groundwater impacted by spills in the nearby vicinity. The groundwater is tapped by phreatophyte plants (meaning ‘living well’) and contaminants are intercepted before the groundwater travels off site. The ‘Woodland’ is designed to thrive in the shaded pedestrian-oriented north-side of the sloped lawn, and the ‘Wet Thicket’ plant community was crafted to visually break up the tall concrete west façade of the pavilion in full sun. Both communities provide the groundwater buffering function perpendicular to the localized subsurface flow.
• PHYTO Air Pollution Buffer: The new bike pavilion also addresses the air pollution caused by the congested highway traffic on the interstate immediately to the west; particulate matter that impacts human health (capable of traveling up to two hundred meters) is captured in an air pollution buffer on the bike pavilion’s roof. Plants with waxy, hairy leaves, shown to reduce particulate matter concentrations in peer reviewed studies, dominate the ‘Coastal Ledge’ Plant community designed, including Populus tremuloides, Morella pensylvanica and Juniperus virginiana. These native plants are also well-adapted to high winds, salt-spray, and well-draining soils.
• PHYTO Bioswale: Inspired by native facultative shoreline vegetation, this salt-tolerant plant community quickly covers the ground and maximizes biomass production targeting nitrogen and phosphorus pollutant removal including Quercus bicolor, Myrica gale, Panicum virginiana, Carex spp. and Iris versicolor.

Plant Communities That Maximize Ecosystem Services

The plant communities are not only designed for phytoremediation, but also to be low-maintenance, mimic native ecosystems, provide habitat, mitigate urban heat-island effect, withstand urban environment stressors, and enhance the experience of the site. For example, the ‘Meadow’ community is designed with natives for pollinators and utilizes a matrix layout, so plants have the ability to move-around, lowering the amount of maintenance required to keep plants in their designated spaces. The key design driver was ‘ecological management not maintenance;’ plant communities evolve and spread native seeds not only within the planting beds, but in the acres of marginalized industrial lands, rail and highway gaps surrounding the site. Corridors that transport people are retooled to transport seeds and replenish the urban seed bank. Any non-natives species included were intentionally selected to be sterile, and straight species of native plants, rather than cultivars, allowing reproduction and maximizing genetic diversity. The contract documents also intentionally specified that plants be procured from several different local nurseries to diversify the gene pool. The design contract includes horticultural monitoring for five years post construction, as plant community establishment is a continuum that should evolve alongside disturbance events and natural systems over time.

A large component of the horticultural experimentation stems from the design of the site’s soils and irrigation systems. The five-foot soil profile on the roof deck was designed to accommodate the novel plant communities; they are low in fertility with a high PH, favoring the stress tolerant plants that can thrive in urban conditions. The soils avoid nutrient-rich conditions that generate both weeds and contaminated stormwater runoff. The irrigation system was also carefully zoned to provide each unique plant community with just enough water to enable establishment. After plant establishment, each zone will be individually turned off; a sustainable strategy for conserving water and targeting specific plant needs.

Sustainability & Climate Resilience

The streetscape doubles as green stormwater infrastructure, capturing and treating all rainfall on site. The tilted lawn area accommodates stormwater storage and infiltration below (through clean soils) sized for future roof runoff that will be generated from surrounding buildings. The topography overall is an innovation for climate resiliency in a wet and warming coastal city vulnerable to sea level rise.

Special consideration was given to material selection to reduce the project’s carbon footprint. For example: Cumaru was chosen over Ipe because it is more sustainably forested. All plants were grown at and sourced from nurseries located within three hundred miles of the site.

The Hood Bike Park project demonstrates the impact that landscape architects can have when research, experimentation, and thoughtful stacking of functions come together to create an intervention for human and natural systems change. Built in 2021, Hood Bike Park is catalyzing the community. The surrounding urban fabric is undergoing the transformation of becoming a place where people and naturalized native plants belong; the post-industrial landscape is transitioning away from vast, vehicular-centric expanses of paving and warehouses toward a vegetated, walkable, bikeable district.