Compost and PFAS
By Gregory T. Federspiel
Recent news of PFAS contamination to drinking wells and gardens from a Westminster composting facility has raised concerns about the plans for an expanded composting facility here in Manchester at the site of our old landfill. The news from the Westminster facility is certainly a cautionary tale and underscores the importance of moving ahead with our plans carefully and with safeguards in place.
PFAS (per- and polyfluoroalkyl substances) are a group of chemicals that persist in the environment and can be harmful to humans if consumed in sufficient quantities. The chemicals are used in a wide array of products, including many that are found in most households. Cosmetics, non-stick cookware, raincoats, and food packaging can all contain PFAS. These “forever” chemicals are widely dispersed throughout the environment due to human activities and unfortunately most people already have PFAS in their body. Drinking water thresholds for PFAS have only recently been set – to date this is the only arena where regulations exist.
The EPA currently has a health advisory of a concentration no more than 70 parts per trillion (ppt) for PFAS in drinking water. Massachusetts has set a threshold of 20 ppt over which treatment to remove PFAS must commence. 1 part per trillion is roughly the equivalent of 1 grain of salt in the water from 20 Olympic size pools. Testing at such small quantities is not easy.
Manchester’s water remains below the threshold for treatment. Gravely Pond has consistently tested below 10 ppt and thus does not require monthly testing at this time. Water samples from the Lincoln Street well, which provides about 40% of our drinking water, has fluctuated between the mid - to the high teens (14-19 ppt) and requires monthly testing. The most recent monthly tests have been at the lower end of this range. With this information in hand the Town hired an engineering firm to develop plans for removing PFAS from the Lincoln Street well should our numbers consistently go over 20 ppt. A new activated carbon filtration system for the Lincoln Street well is estimated to cost about $8 million. (Residents can also install household filter systems – if you do make sure the system is design to remove PFAS if that is your objective.
Black Earth Compost, the local company that currently operates the open compost site off Upper School Street, regularly tests for the presence of PFAS in their compost. Not surprisingly, PFAS are present but at low levels, below the state’s 20 ppt threshold. Black Earth composts food scraps, yard waste (but not grass clippings to avoid lawn chemicals) and chipped wood. This contrasts with the Westminster facility that takes in large quantities of sewer plant sludge and by-products from paper manufacturing which are both likely sources of PFAS.
The current School Street composting operations are not contained within a structure thus there is the potential for runoff from the site. The new facility to be constructed this fall at the site of our current transfer station will be self-contained. Any leachate from the composting process will be collected and either put back to keep the compost at the proper moisture level for maximum decomposition or be hauled away and disposed of elsewhere. Finished compost will be stored in the open on top of the old landfill. A heavy rainstorm could cause some leachate to migrate through the grasses and into the old landfill pile. Total quantities of compost are less than 2% of what is being processes at the Westminster facility.
We currently also monitor PFAS coming from the old landfill. Some of the monitoring wells report concentrations as high as 228 ppt. The good news is that there does not appear to be a hydrological connection between the old landfill and Gravely Pond given the very low concentrations seen in the Pond. Further testing is planned to confirm this. With the help of the Water Resources Task Force further analysis of our drinking supply watersheds will be undertaken.
PFAS regulations are evolving and will require us to stay abreast of new developments. The EPA is promulgating new health advisories (not enforceable) for a sub-set of 4 PFAS, 2 at non-detect levels. And our DPW will continue to monitor PFAS levels in our drinking water and within our watersheds, including the new compost facility. The new facility should pose less of a threat then the current operations with the new enclosed processing building. If we need to, we can prohibit outdoor storage of finished compost. Updates on PFAS as well as the compost facility will be posted on the Town’s web stie.