Each month the EPA has a public webinar focused on their water research. Its April 23 session featured Cape Cod and the results of a study comparing sewers with alternatives to sewers in energy use, life cycle costs, greenhouse gases and several other qualities. At least 70 people from across the country participated, including Falmouth residents David Dow, Hilde Maingay and me.
The report “Re-Visioning 21st Century Water Infrastructure: Solving for the Pattern of Sustainability” recognizes that old conventional infrastructure (septic tanks and sewers) works fine to protect public health from pathogens, but has inherent unintended consequences in the increasingly critical areas of resource recovery, pharmaceuticals and collateral damage to the environment. Like Falmouth, many communities are approaching a point of investment in waste and water infrastructure, and such investment should consider infrastructure that is sustainable and resilient in the long-term.
The EPA compared five alternative scenarios for replacing household septic systems on Cape Cod as part of a regional effort to address coastal eutrophication problems. The study analyzed sewer systems, composting toilets, urine-diverting toilets, blackwater-to-biogas, household greywater re-use, and rainwater collection and use, in terms of:
• Public health
• Recovery of resources
• Life cycle costs
• Greenhouse gases
• Degree of improvement
• Energy use
• Water use
• Environmental impacts
Some Winners and Losers
Public health: Surprisingly, sewers had the highest public health risk, due to cross contamination of sewer water and drinking water underground between leaking pipes.
Recovery of resources: Eco-toilets recover the most nutrients and save the most water; sewers wasted the most nutrients and water.
Life cycle costs: The eco-toilet infrastructure has the lowest lifecycle costs.
Energy use: Sewers required the most energy. The biogas system requires the least external energy, since it recovers energy from collected organic wastes. But it requires pumps at each house and a buried collection system like a sewer.
There are many other valuable lessons that Falmouth can learn about water service systems, before investing $40 million in sewer technology with multiple deficiencies, highest life-cycle and energy costs, and largest contribution to greenhouse gases. This new information could help us carefully rethink how to instead provide sustainable, affordable water services and recovery of nutrient resources, while cleaning our waters. There is no time to waste.
Earle A. Barnhart