PORTLAND, Maine — The city, along with an organization administering 11 city-owned gardens, has closed the Libbytown community garden due to soil contamination.
Both arsenic and benzo(a)pyrene, a type of polycyclic aromatic hydrocarbon commonly known as BaP, were found at the site in levels exceeding state safety standards, according to Portland spokesperson Jessica Grondin.
BaP is a widespread compound resulting from incomplete burning of organic matter. It can be toxic and is the prime carcinogen in cigarette smoke. Arsenic is also toxic and can cause cancer. Both substances are common in former industrial sites where coal or coal ash have been present.
The Libbytown community garden sits at the corner of Douglass and St. James streets, adjacent to land once owned by the Portland Gaslight Company, which made gas from coal in the 19th and 20th centuries. The garden is also near railroad tracks.
“We’re not trying to panic anyone,” Grondin said. “More like we’re trying to get a pulse on this and get ahead of it.”
To remedy the situation, the city plans to reconstruct the Libbytown garden, building raised beds on top of a barrier fabric, which will keep consumable plants above the contaminated soil. Reconstruction work at the Libbytown garden, which first opened in 2016, is expected to start on Monday and be completed by the end of May.
The city also intends to test the soil at all of its other community gardens in the coming weeks, starting with the North Street, Boyd Street, Payson Park and Casco Bay locations.
Cultivating Community, the nonprofit which administers those sites, is asking gardeners at the four locations to hold off on spring planting until test results are complete. Executive Director Silvan Shawe said that should be done by the first of June.
“Gardeners have been disappointed but understanding,” Shawe said. “We’re prioritizing safety for the long term.”
Though previous soil testing has been done at all 11 community gardens in Portland, Grondin said the new testing would be more comprehensive than before.
The Libbytown contamination was discovered when a private contractor, hired by the city, recently performed comprehensive soil tests in preparation for replacing the Kiwanis Pool, which is located directly adjacent to the garden. When both arsenic and BaP were found, it was decided to also check the garden.
Soil samples were then collected at nine different locations inside the garden and tested for the presence of more than 90 different chemicals.
In one of the nine samples, BaP was measured at 5.5 milligrams per kilogram. The Maine Department of Environmental Protection recommends remediation actions be taken if BaP is detected at anything more than 1.6 milligrams per kilogram in a residential setting, or over 4.5 milligrams per kilogram in a park setting.
In three of the nine samples, arsenic was measured at between 9.96 and 13.8 milligrams per kilogram. Maine recommends remediation if arsenic is detected at anything more than 9.3 milligrams per kilogram in a residential setting or over 26 milligrams per kilogram in a park setting.
Though the levels found are high enough to trigger remediation, Grondin said, they were not astronomical, and it was fortunate that other types of chemicals were not found.
“We will continue to communicate with gardeners as we get the rest of the tests back and are hoping to get people back to their planting season as quickly as possible,” she said.
