For a city that receives an average of over 40 inches of rainfall every year, why is it that Boston, Massachusetts needs to pump in water from 65-miles away? Why is it that public health officials recommend avoiding contact with local water bodies for at least 48-hours after a rainstorm? Why is it that water rates on utility bills continue to rise?
In years like 2016, when drought has resulted in water restrictions and major crop losses in Massachusetts, local water capture and reuse seems more appealing than ever, (see U.S. Drought Monitor for more drought details). “Green infrastructure” – engineering and design that mimics natural processes to protect and restore environmental and public health – offers some alternative solutions for current and future water woes. From water retention basins, to water filtration plazas, green infrastructure holds promise for a more efficient, resilient, and cleaner water future.
For Boston, “local water” at about 44 inches per year could mean the ability to capture about 27,000 gallons of water for every 1,000 square foot roof, (for reference, the Old State House has a roof about quadruple the size of that. For history buffs out there, this historic building in Boston is where the Declaration of Independence was read to the masses back in 1776). From drinking, cleaning, and bathing, to fire control, irrigation, and industrial processes, water is a key fixture in everyday life. Yet, the water system as it exists today is made up of a distribution network that may be neither healthy or efficient, (see the Massachusetts Water Resources Authority for more on where Boston’s water comes from). As one of the oldest cities in the United States, aging infrastructure is an omnipresent concern.
One major health concern for Bostonians is that many households are connected to the water supply via lead pipes, which were banned in 1989 due to the toxic metal’s ability to leach into water and harm public health, (namely brain and kidney damage), particularly children. In addition, the water system has a hard time handling large rain events, and experiences combined sewer overflows where rainwater and sanitary wastewater (aka poop water to be blunt), mix and discharge into the Charles River, Alewife Brook, or other local waterways to prevent back-up into businesses and homes, or up onto streets. These water quality health concerns seem to be enough evidence to act, and green infrastructure seems to be a critical tool for updating the water system.
Small-scale water capture, storage, treatment, and reuse technologies are available today. Infrastructure improvement costs and lack of water value, knowledge, and awareness on the level of the citizen and even politician, however, deter its rapid deployment and advancement. Two examples of water-wise green infrastructure in the Boston Harbor Watershed demonstrate a variety of benefits offered from projects that are "designed with nature" (a la Ian McHarg).
First, in Cambridge--just across the river north of Boston, the Cambridge Department of Public Works commissioned a private firm to help alleviate the public health threat related to combined sewer overflows and provide a new public amenity while they were at it. The Alewife Reservation Stormwater Wetland was the result. Developing Cambridge's first hydraulic stormwater model to simulate and design for 10-year storms and reduce discharges of stormwater to the Alewife Brook, the team planted 120,000 native plant species, constructed a pedestrian/cyclist trail around the reserve, and engineered a stormwater wetland that has helped reduce sewer overflows by 84%. Read more on the MWH Global and City of Cambridge project here.
Complementary to constructed stormwater wetlands and retention basins, green roofs provide another effective green infrastructure tool for improving water quality. Green roofs – vegetated coverings on buildings as opposed to traditional tile, asphalt, metal roof coverings – combat the impervious quality of urban landscapes. Green roof benefits include natural filtration of rainfall and improvement to runoff quality, a reduction in the amount of run-off coming off buildings, improved roof membrane life span, increased biodiversity and wildlife, reduction in the urban heat island effect, and noise abatement for interior spaces.
Also located in Cambridge, this example green roof is a 10,000-square foot extensive roof at a Harvard Graduate Student Housing building. While the building was constructed in the 1920s, the retrofitted green roof came in 2004, transforming the once barren roof of the parking garage into an outdoor amenity for residents. The project team states the ‘Garden Roof’ will significantly increase the life expectancy of the roof and will help control stormwater runoff with its 4-inch-deep vegetated ecosystem comprised of succulents, sedums, and other drought tolerant plant varieties. The plants were chosen specifically for their capability to withstand Boston’s day-night and seasonal temperature fluctuations.
Are these water-wise green infrastructure projects worth the investment? Are today’s water quality and supply concerns enough to begin transforming the existing system? Share your thoughts and your city's stories in the comments area below.
Credits: Images by Alyssa Curran. Data linked to sources.