by Max Rome, Nick Bernat, and Lauren Valle
In precolonial times the Blackstone River was a large and ecologically-rich tidal river. As it meandered 49 miles from present day Worcester, MA to Providence, RI the Blackstone drained an area of 479 square miles and fell 450 feet. Known as Kittacuck, “great tidal river,” to the native peoples who lived along these waters, the bountiful river provided wetland habitat for native mollusks, anadromous fishes, and other important species.
William Blackstone, from whom the Blackstone Valley gets its name, established the first English settlement in Rhode Island in 1635. The valley quickly attracted other settlers, and when Samuel Slater opened the first U.S. mill in 1793 (mechanical spinning machines for the processing of cotton), he opened the door to other water-powered sites along the river. By the 1830s, there was one dam for every mile of river along the main river and its tributaries, and the Blackstone’s tidal flow was irrevocably altered.
A Legacy of Contamination
This diverse and intensive industrial use of the Blackstone River’s hydropower earned it such titles as “The Birthplace of the Industrial Revolution” and “America’s Hardest Working River.” At the peak of its power, the output of mills along the Blackstone River rivaled that of the Hoover Dam. In addition to supplying power, the Blackstone River was the dumping ground for sewage and the wastes of both agriculture and industry. Textile manufacturers discharged dyes, leather and metalworking plants discharged heavy metals, and woodworking companies discharged varnish, solvents, and paints. Many of these pollutants can still be found in the river’s sediments today, over one hundred years after they were released. This all too typical exploitation of the river left a radically-altered hydrology and a legacy of polluted water, contaminated sediments, and degraded habitat.
Between 1920 and 1980 pressure from southern mills resulted in the closure of most of the Blackstone Valley’s woolen and worsted mills, the population declined, and by 1971 the Blackstone River was labeled “one of America’s most polluted rivers,” according to Audubon Magazine. (Kerr, 1990) During the early 1970s, citizens interested in restoring the Blackstone River’s water and the land along it formed the Blackstone River Watershed Association. This association and other groups in the Blackstone Valley lobbied successfully for parkland development along the river. In 1986, Congress established the Blackstone River Valley National Heritage Corridor to preserve the significant historic and cultural lands, waterways, and structures within the valley. Today the river has obtained a “Class C” rating: hazardous for all activities except canoeing and kayaking. While little industry remains, the Blackstone still receives water from a number of wastewater treatment plants, and at times the water in the upper Blackstone smells distinctly of sewage.
Ecological Design, Creating a River within the River
The Fisherville Mill is an acute though typical example of contamination and ecological challenge on the Blackstone. In its final iterations, the mill produced foam rubber and vinyl for automobile seating. The mill ceased operation in 1986 and burned to the ground in the last year of the millennium. The massive fire decimated the area and left the site and soils heavily contaminated with volatile organic compounds (VOCs), asbestos, heavy metals, and the long-chain petroleum hydrocarbons derived from #6 and #4 crude oil.
John Todd Ecological Design (JTED) became involved with the cleanup of the Fisherville Mill site in 2006 after significant clean up and remediation of the site had already occurred. While many of the worst concentrations of oils and solvents had been removed, more remained locked in sediment and the banks of the canal and entered the water with every rain. We set out to find an intervention that could give the canal the added capacity it needed to deal with this influx of contaminants, to metabolize the pollutants without compromising the already fragile ecology. We started our investigation with a pilot study looking at a multi-vector approach for the degradation of petroleum hydrocarbons and volatile organic compounds. We experimented with a range of ecological communities including mycelia of the white rot fungal families and, after a year of data collection, had enough information to begin our full-scale design.
The result of our experimentation is the Fisherville Canal restorer, a unique hybrid of in-stream and side-stream treatments. Taken together, the two treatments create a powerful circulating loop of regenerated ecology: a stream within a stream. Water drawn from the canal is purified and returned, and re-seeding the canal with healthy ecology. The system functions as a complex whole but can be understood in terms of four separated stages of treatment.
Stage one: Sediment digestion. In a body of water living with contaminants for as long as the Blackstone River, the sediments are already home to a range of bacteria at work digesting these contaminants. The natural degradation process is slow and its rate is often powerfully limited by a range of factors including flow rate, dissolved oxygen content, water chemistry, and availability of surface area for attached growth. We began our treatment by designing large bottom filters capable of supplying the micro-organisms with the ingredients they lack. Within these filters, micro-organisms colonize the extensive surface area of the enclosed media, and then river water and sediment are pulsed through the filters allowing attached growth organisms to graze on the easily available suspended material. As material builds up in pockets of the system it is broken back down by the filters’ residents.
Stage two: Myco-Reactors. The water that passes through the sediment digestion filters is next trickled though bins of inoculated mycelium, including Irpex lacteus, Stropharia anulata rugoso (garden giant), Trametes versicolor (Turkey tail), and Pleurotus ostreatus (oyster mushroom).
In these cells the complex, lignin-dissolving, exo-cellular enzymes secreted by the mycelium are collected in the flowing water. Some contaminants and compounds are adsorbed by the wood chip media, and degradation occurs through a host of organisms including black slime molds and other fungal partners.
Stage three: Aquatic Cells. A series of six vertical tanks situated in a greenhouse contain a diversity of algae, bacteria, protozoa, zooplankton, snails, and fishes. Here in a complex sun- and oxygen-rich environment, the water is purified and seeded with the living organisms found along the Blackstone River. These cells serve as prolonged contact chambers in which material remains in contact with fungal enzymes. As compounds are broken apart they are then metabolized by a range of creatures living within the cells.
Stage four: Floating Restorer. The floating restorer is a thickly-planted, floating raft. Water from the greenhouse is discharged here through a series of sprinkler nozzles. This water then flows through fruiting mushrooms and suspended root growth before it re-enters the river. The floating restorer creates a pocket of clean oxygen and life-rich water that supports a diversity of life.
During the Fisherville system’s first year of operation we observed a gradually accelerating reduction of petroleum hydrocarbons. By the time the system reached a steady state of operation, a reduction in excess of 95% of total petroleum hydrocarbons was observed between the influent river water and the purified water passing through our system. Today we are working to monitor the river in order to understand the effects of the system on the entire water body. Our interest is in finding the point at which we tip the balance and create a critical mass of buffer against contamination, healthy ecology, and purified water so that the system can begin to heal itself.
Extending the Project
With the working system in place, our work now is focused on education and on expanding the system down the length of the Blackstone canals. These aims are being pursued through the Living Systems Laboratory (LSL) and an ongoing series of workshops. The LSL functions as a public and transparent bio-remediation and ecological design site where students, educators, scientists, landscape architects, and the public at large work together to address the complex issues of such a historically-significant site.
The land that Living Systems Laboratory occupies was donated to the town of Grafton as a public park that is now used regularly by joggers, dog walkers and those who want to enjoy the natural beauty of the area. Anyone can visit and use the LSL for education and research. The National Park Service is using the LSL as a pilot location for developing its science-education program. Several graduate students from nearby universities are using the LSL to research their theses. The LSL has established research collaborations with the Brown University Superfund Research Labs, Clark University, Worcester Polytechnic Institute, and the Conway School of Landscape Design.
The vision of the Living Systems Laboratory is to facilitate the clean-up of the entire length of Blackstone River. Many current proposals call for a fishable, swimmable Blackstone. Proposals are focused and effectively target limiting industrial, wastewater, and stormwater discharges into the river. A full length Blackstone River Restorer would work in tandem with these efforts to limit pollution and would move toward active ecological rehabilitation of the river. The Blackstone River Restorer will accomplish rehabilitation in three discrete but synergetic ways:
Cleaning of Sediment: At Grafton we have found that a 95% reduction of residual hydrocarbons can be achieved by using airlifted bottom filters. When bacterial communities already established in the layers of sediment are given access to surface area for attached growth and optimized flows, they are able to rapidly degrade many persistent contaminants. The upwelling of degraded material into an oxygenated zone of root growth creates a dynamic ecological niche in which newly available nutrients and organic compounds fuel growth.
Provision of Refugia: Upwelling, aeration, and a zone of intensive plant growth create an oasis of cleaner water within the degraded river. The river restorer contributes new habitat for emergent plant species and water quality sensitive invertebrates, amphibians, and fishes. It also serves as a refuge for turtles and carp already living in the river.
Ecological Seeding: In addition to providing a bubble of cleaner water, the restorer constitutes an ecological chemostat, constantly releasing and recirculating plants and animals back into the river. As water quality improves, these organisms find their place and the ecology of the river comes to resemble the ecology of the restorer.
A Unique Corridor
The Blackstone River Restorer will contribute to the health of the river indirectly by improving access and creating a sense of stewardship. A walkway along the length of the river would establish a wonderful and unique pedestrian route from Worcester to Providence and offer walkers a unique view of both the current and future Blackstone -canalized shores and degraded water, but a corridor constituting a healthy and bio-diverse alternate shoreline. Tying into and enhancing existing hiking and walking paths, a Restorer Walkway would string together otherwise isolated sections of parkland and might even temporarily house sections of the Blackstone Valley Bikeway.
A Learning Landscape
In addition to producing native wetland plants, the restorer can be a laboratory for the production of nursery plants, fruit trees, and species to be used for further restoration work. A grant submitted to the Massachusetts Department of Agriculture seeks to begin this work. We propose planting crops in specially designed floating beds that will need neither watering nor fertilizer and might be harvested by boat. Research will need to be done to investigate crops that will thrive in this environment and produce fruit or seed safe for human consumption.
We would like to acknowledge and thank the many people and institutions as well as the town of Grafton for their help with this project. We believe that just as the Blackstone led the industrial revolution it is poised to lead a second revolution, to be an exemplar of the capacity of humans working with nature to heal our land and waters and of a new generation of ecological infrastructure by parlaying a legacy of contamination into a future of sustained health and engagement.
About the Authors
Max Rome is a project manager for John Todd Ecological Design (JTED). He holds a degree in Civil and Environmental Engineering from UMass Amherst where he studied mechanisms of sludge reduction in wastewater treatment. Max has been with the JTED since 2010, working on a range of projects including ecological wastewater treatment and the rehabilitation of rivers contaminated by informal settlement run-off. He may be reached at email@example.com
Nick Bernat is the site manager at the Living Systems Laboratory for ecological research, and he maintains and operates the Fisherville Eco-Machine™ in Grafton, MA. Nick graduated from the Farmschool’s sustainable agriculture apprenticeship in 2008 and has studied at Boston Architectural College’s Landscape Institute, focusing on native plant ecologies, sustainable design and remediation. Nick owns Natura Landscape Design Inc., dedicated to artistic design compatible with native ecologies. He may be reached at firstname.lastname@example.org.
Lauren Valle is a project coordinator with John Todd Ecological Design (JTED). She graduated from Columbia University in New York. She has a background in permaculture, in sustainable land management, and as an entrepreneur. Lauren brings her passion for environmental issues and a proactive participation in solutions-based activism to JTED. She may be reached at email@example.com.