Andover | Red Oaks neighborhood groundwater contamination

In 2021, the Minnesota Pollution Control Agency (MPCA) began sampling private wells in the Red Oaks neighborhood for 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS) as these contaminants can be associated with former landfills.

The MPCA discovered contamination from the chemical 1,4-dioxane while conducting water sampling near the closed Waste Disposal Engineering (WDE) landfill in Andover (see Figure 1 below). The chemical was found by MPCA above the Minnesota Department of Health’s (MDH) health risk limit (HRL) in private residential wells located near Bunker Lake Boulevard and Crosstown Boulevard in the eastern portion of the Red Oaks neighborhood. The MDH develops HRLs to evaluate potential human health risks from exposures to chemicals in groundwater. The MPCA designated the eastern portion of the Red Oaks neighborhood where 1,4-dioxane was detected above the HRL as the “mitigation area.” The western portion of the Red Oaks neighborhood where 1,4-dioxane was not detected above the HRL was designated as the “monitoring area.” The mitigation area was connected to city water in 2023-2024 using a $6.1 million grant from the MPCA to the city of Andover.

Samples collected from private wells were also analyzed for PFAS compounds. The lowering of the State of Minnesota’s HRLs for two PFAS compounds in 2025 resulted in numerous private wells in the monitoring area exceeding these values (see Figure 2 below). 

The source(s) of the 1,4-dioxane and PFAS in groundwater have not been determined at this time; however, two potential sources in the immediate vicinity of these neighborhoods include the closed WDE landfill and the South Andover Superfund site. Figure 1 below shows the locations of the Red Oaks neighborhood and the WDE closed landfill and South Andover Superfund site. 

The MPCA has completed multiple rounds of private residential well sampling in the Red Oaks neighborhood, beginning in 2021. Forty-six (46) homes in the Red Oaks monitoring area have PFAS levels in their private residential wells at or above MDH health risk limits. MPCA is providing bottled water as an interim mitigation measure to these homes.

Long term solution for clean drinking water

In 2023, the MPCA secured $6.1 million in bond funding from the Legislature to connect the mitigation area of Red Oaks (eastern portion) to the city of Andover’s municipal water supply system and to seal the existing residential water wells. The city of Andover locally contracted the municipal supply connection work and completed connection of 93 homes in the Red Oaks mitigation area to the municipal water supply. 

In 2025, the MPCA secured $8 million in bonding to connect the homes in the monitoring area of Red Oaks (western portion) to municipal water. In 2025, the MPCA entered into a grant agreement with the city of Andover for the bond funding, including scheduling and coordinating the details of the project, with an anticipated construction schedule of 2026-2027.

Ongoing investigations to determine contamination source(s) in Red Oaks

To better understand the area of contamination and make progress toward identifying the source(s) of the groundwater contamination in Red Oaks, the MPCA is conducting additional groundwater investigation and monitoring related to the WDE closed landfill. In addition, the U.S. Environmental Protection Agency (EPA) is overseeing additional environmental investigation related to the South Andover Superfund site.

Both sites are conducting extensive groundwater testing using permanent groundwater monitoring wells to evaluate where the contamination may have originated from and to confirm where groundwater is moving beneath the ground surface.