By now, those readers following the entire series have a handle on the framework of CRWA’s restorative approach to urban water infrastructure. Based on “understand and replicate nature” assessments that ultimately link all urban water, our approach holds immense promise.
|Stream daylight visualization in an urban setting|
Until now, I have avoided making long lists of the environmental benefits, but at this juncture, before the series becomes more site specific and financial and economic evaluations dominate the dialog, an annotated list of benefits might prove useful. I have learned over the past 25 years that, of themselves, environmentally sound outcomes are rarely motivation for fundamental change. Our tendency instead is to “solve” each environmental regulatory “problem” with distinct, separate, one-off engineering “solutions.” I hope, however, society will at last begin to evaluate entire landscapes and work with nature. Nature’s Principles so applied will, over time, make a real difference in the quality of our lives, and in our resilience.
Here, then, is the list of benefits:
- Fossil Fuel Use Reductions: It is difficult to give concrete figures because in a distributed system each plant will be different, but those using the system’s thermal energy to heat and cool their homes and businesses would not be burning natural gas or fuel oil. Their power will come from a renewable, currently underutilized source.
- Greenhouse Gas Emission Reductions: Distributed plants provide multiple opportunities for disposal of local food waste (also known as “source separated organics”) from nearby food waste generators. This leads to an overall reduction in trucking of food waste loads with reductions in carbon dioxide emissions. Additionally, the use of wastewater organics and food waste to generate electricity captures their carbon emissions, reducing emissions versus landfill disposal.
- Flood Control: Restored tributaries in Boston would increase flood storage and conveyance over existing conditions. Our design for Site 1, fully implemented – at some impact to development - would increase flood control over existing conditions by 400 times for the surrounding district/subwatershed.
- Evaporative City Cooling: Restored streams and the plant life they encourage would help reduce the “heat island effect” of pavement and buildings through evaporation and transpiration, providing relief as temperatures increase, and reducing energy demand.
- Drought Resilience: Using reclaimed water after treatment, and then re-introducing that water back to the environment provides deep resilience to extended periods of drought both by reducing demand on potable supplies and recharging local fresh water resources.
- Restored River and Stream Flow: If the Massachusetts Water Resource Authority (MWRA) system were transformed, over time, to distributed treatment plants, treated water discharged from each plant to surrounding restored streams, together with increased groundwater flow from rain gardens and swales, would increase flow in tributaries and rivers. Increased groundwater and tributary flow would lower river temperatures and help to regulate their oxygen concentrations. Use of reclaimed water also would reduce demands on our water reservoirs, with the potential to enhance flows to the Swift and Nashua Rivers, the source Boston’s central Massachusetts reservoirs.
- Reduction of Phosphorous Pollution in Our Rivers and Tributaries: Infiltration of water collected in rain gardens and swales incorporated throughout new greening districts would allow selected plants to remove phosphorous from the water. Additionally, as phosphorous moves through the ground, it is adsorbed and removed from the water, significantly enhancing water quality.
- Aesthetics and Open Space: The cleaning of Boston Harbor and the Charles River over the past 20 years is testament to the value of clean rivers and harbors to urban life and development. Restored urban streams, their meanders and life, would do the same for neighborhoods across the City.
- Distributed Reclaimed Water: In the event of catastrophic storms, having distributed sources of reliable water will be critical. While drinking water can be brought in on 18 wheelers, water to flush toilets and run households will be needed; distributed reclaimed wastewater can provide this.
- Distributed Energy: In the event of catastrophic storms, having distributed sources of reliable energy will also be critical.
- Community Development: Distributed plants would provide renewable sources of electricity, thermal energy, and reclaimed water. Restored urban streams would provide flood control. Both will prove valuable to community revitalization and development.
- Restored Wildlife: Restored flow, clean water, lower temperatures, enhanced fisheries, plant life, birds, water, and life.
And, Of Course, a Nearly Fully Restored Charles River: CRWA’s work understanding the Charles over the past 20 years has been motivated by our mission to restore and care for the Charles and its watershed. That mission has led our queries and our science and engineering, and has brought us to a place where the achievement of nearly full restoration is within our grasp.
It’s a pretty long list.