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Cambridge Water Department Proactively Battling the Forever Chemical PFAS

Monday, November 21, 2022

Based on nothing more than their name, per- and polyfluoroalkyl substances (PFAS) certainly are not an ingredient you want to find in your sandwich wrap. But recent studies show, they’re everywhere — in your pizza box, cosmetic bag, and maybe even in your clothing.

PFAS are widely used, long lasting chemicals, components of which break down very slowly over time. You may have even heard them being referred to as “forever chemicals.” Because of their widespread use and persistence in the environment, PFAS are now being found in water, air, fish, and soil across the nation and the globe.

The many thousands of PFAS chemicals found in different products make it a challenge to study and assess its potential human health and environmental risks. Due to the long-term use of PFAS compounds, it’s no surprise to find these forever chemicals in public drinking water systems across the country. Luckily for Cambridge residents, Massachusetts has some of the strictest regulations for drinking water in the country. In 2020, The Massachusetts Department of Environmental Protection (MassDEP) promulgated a regulation for PFAS which went into effect on January 1, 2021. The regulation is a quarterly average of six specific PFAS compounds not to exceed 20 parts per trillion (ppt).

What is Cambridge Doing?

The Cambridge Water Department (CWD) began voluntarily sampling for PFAS in August 2019 and also initiated the development of a “PFAS reduction plan.” There is a seasonal variation in Cambridge’s PFAS concentrations, with the highest concentrations occurring in the late summer months and the lowest in the colder winter months. With support from MassDEP, a bench scale pilot study was developed to test the effectiveness of different filtering media to reduce PFAS concentrations. That study was completed by the end of 2021. Results determined that granular activated carbon (GAC) was the best method for CWD to significantly reduce Cambridge’s PFAS concentrations.

GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed via pretreatment methods. The filters have always been part of Cambridge’s operating design. With PFAS center stage, and emerging health risks and stricter regulations on the horizon, CWD will make GAC replacement a preventative maintenance practice moving forward. Filter media changeouts are a recommended standard, especially now with PFAS in ground and surface waters across the country. Changing out the GAC filter media is not much different than changing out a Brita or home filter. After a certain amount of time or a certain volume, you change the filter. The differences are that CWD’s filters are fixed in place and the filter media changeout is simply the exchange of the old carbon inside the filter with new carbon.

In spring 2022, CWD bid out and awarded the contract for the replacement of the filter media in its 6 filters. The project was scheduled to start this summer, but due to the COVID-19 pandemic and supply chain issues, the manufacturing, delivery, and installation processes were affected and severely delayed. When CWD’s initial August 2022 PFAS result came in over 20 ppt, which was subsequently rejected, the decision to switch to Massachusetts Water Resource Authority (MWRA) was made and carried out on August 30, 2022. CWD has remained in compliance with state and federal guidelines and subsequent regulation since PFAS was identified in Cambridge’s water in 2019.

Cambridge’s DEP approved finished water PFAS6 result for August, before the successful installation of the new media, was 17.1ppt. With the new GAC filter media installed in just two filters, PFAS6 results in all 6 filters working together in parallel is around 3ppt. The two filters with new GAC media are now testing individually under 2.0ppt also called “non-detect” (ND) levels. The City expects continued reductions in PFAS levels in the treated water as GAC media is installed in the remaining 4 filters over the next two months.

Testing confirmed that PFAS levels of 3 ppt were well below 10 ppt (which is half the allowable safe limit not to exceed a quarterly average of 20ppt). CWD met with MassDEP to determine the next steps and to get approval to go back online. With approval from MassDEP and City officials, CWD went back online November 19, 2022, supplying the City with water from its own supply. Changeouts on the next two filters started the week of November 28. After successful completion, CWD will have 4 of 6 filters with new GAC filter media. Plans to complete the last two filters for a total of 6, are being scheduled for the new year.

The Water Department continuously tests its water to ensure compliance with US Environmental Protection Agency and Massachusetts Department of Environmental Protection regulations and typically surpasses all regulations. Additionally, the Cambridge Water Department has an on-site certified laboratory that tests many water quality parameters to optimize its treatment performance and water quality. Annually, all water users in the city receive a detailed water quality report by mail in June.

Learn more at Cambridgema.gov/water.

View Cambridge Water Department Update Video (November 2022)


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