Velsicol Chemical is located at 500 Bankson Street in St. Louis and was the site of a chemical manufacturing plant from 1936 to 1978. Chemicals produced here included fire retardant PBB and the pesticide DDT. Since 1982, a slurry wall was put into place to contain chemicals onsite, a clay cap was put on the contaminated soil, and other actions taken to cleanup contaminants. In March 2025, EPA’s contractor sampled 74 monitoring wells, with 37 wells being sampled from the shallow aquifer, and 37 being from the lower aquifer. PFAS was detected in all 37 shallow monitoring wells, and in 32 of the lower aquifer monitoring wells. The highest PFAS results were 150 ppt PFHxS (compared to 51 ppt) and 87 ppt PFOA (compared to 8 ppt).
There are three groundwater units present at the Velsicol Chemical Site: Shallow Unit – The shallow unit aquifer is characterized by groundwater that flows primarily towards the Pine River, with a local groundwater divide present just outside the southeast portion of the site. Lower Unit – The lower unit aquifer is characterized by groundwater that primarily flows from west to east, and the groundwater elevation change from west to east across the site area is approximately 4 feet. Former City Well Intake Zone – The former city well intake aquifer is characterized by groundwater that primarily flows from west to east, which is consistent with regional groundwater flow.
View an aerial image of the site.
This app provides access to multiple datasets from Michigan’s PFAS Action Response Team (MPART), including data on official sites, surface water, public water supplies, and fish sampling.
Historically, residential well sampling was conducted by DHHS at locations directly north of the site across the Pine River and locations west of the site. All nearby residents are now connected to municipal water through the Gratiot Area Water Authority to the City of St. Louis.
Erik Martinson, MartinsonE@Michigan.gov or 517-285-3978
