Wednesday, July 24, 2024

A charger for electric vehicles in front of a mural in Cambridge’s Central Square. (Photo: Marc Levy)

The next 10 years will bring major utility developments for Cambridge and New England, revealed in the Cambridge Planning Board’s annual utility update on June 27. For many of the developments, climate change disaster mitigation and green infrastructure lay at the core.

Cambridge released details on Wednesday of a pilot program that would grant owners of electric vehicles a permit to run charging cords across sidewalks. Department of Public Works engineering director Jim Wilcox noted that holders would need to meet several requirements, laid out in a press release by the city, including owners not having access to off-street parking and being able to provide a ramp over cords so they didn’t become impediments to people with disabilities.

The city and the Eversource power utility are looking to build more infrastructure to accommodate the more than 5,000 – and growing – electric vehicles in Cambridge; DPW is looking to install 100 charging stations by 2027, and Eversource includes in its planning projections for electric vehicles, including what electric load growth would look like if every car was converted to electric, the company’s Sophia Zhang said.

Many other aspects of the utility update were familiar from recent months.

Sewer separation

One such long-discussed plan involves a sewer separation process. In Cambridge, most draining sewage is combined with stormwater and treated at the Deer Island water treatment plant, Wilcox said.

During extreme rains, such systems can overflow, causing the combination of stormwater and sewage to be routed to waterways – in Cambridge and Somerville’s case, the Alewife Brook leading to the Mystic and Charles rivers. These overflows are necessary to prevent flooding of sewage in streets and homes, but can cause the quality of waterways to degrade temporarily.

Sewer separation aims to create dedicated systems for sewage and for rainwater, limiting the impact on water systems and decreasing the chance of flooding with sewage.

A DPW map shows many areas have already been converted to separated systems. Those that still require separation are most challenging, Wilcox said, because they require building outflow pipes controlled by the state’s Department of Conservation and Recreation – increasing the red tape.

A variance by the Massachusetts Department of Environmental Protection lowers water quality standards for Cambridge, Somerville and the Massachusetts Water Resources Authority, thus allowing some level of overflow to occur. But the goal of the variance and Cambridge is to eliminate the outflows – eventually, Wilcox said. The planning and design process began in June and is expected to run through December 2026, including a series of community meetings in which Cambridge, Somerville and the MWRA presents information to the public and solicits feedback on plans, he said.

This variance requires that the city take into account climate change and associated flooding when planning combined and separated systems, but while limiting the amount of overflows as much as possible – according to Wilcox, in a way unique in the United States.

Climate disaster mitigation

Cambridge’s plans to mitigate the effects of climate change-induced flooding and urban heat were also discussed.

Cambridge, including bodies such as its Planning Board, require developers to incorporate flooding impacts into building plans – to the degree that on June 8 the board continued an application for a 22-apartment building at 48-50 Bishop Allen Drive, Central Square, because its developers were working with outdated flood maps.

Other solutions are in the works as well, Wilcox said, such as flood relief tanks that would store water during heavy rains. In dealing with potential flooding at the Charles and Mystic River dams from rising sea levels and storm surges, the city is in contact with Arlington to plan how to use a federal grant to raise dams, increase the flow of water from them and build walls to minimize the impact of overflows, Wilcox said.

This update comes in the wake of heavy flash floods from New England to China, India, and Spain.

Water and urban heat

In terms of water conservation, Mark Gallagher, director of engineering and distribution with the Water Department, noted that the city has reduced its water consumption despite a steadily growing population, largely due to reducing the number of leaks and improved monitoring of the pipe system. The city has also reduced its levels of PFAS – toxic synthetic chemicals sometimes called “forever chemicals” due to their long lives.

Regulations in the past two years allow for a combined total of 20 parts per trillion of PFAS in Massachusetts. “We replaced all of the granular activated carbon in all of our filters – the six filters in the plant – which allowed us to reduce PFAS levels from around 20 parts per trillion down to basically a non-detect level starting in fall of last year to present,” Gallagher said.

Cambridge is also implementing some small measures to reduce the worst of urban heat, including the planting of new trees and an “aggressive” watering program, Wilcox said. By increasing the street canopy to provide 60 percent shade, he said, the ground could cool by 10 degrees. Additionally, the city is looking to cover its parking lots and roads with lighter colors to reduce their heat-trapping effects.