Saint Paul: Ford Site

Aerial view of Ford site.The Ford Site is the former Ford Motor Company assembly plant in the Highland Park neighborhood of Saint Paul, Minn. The plant operated from 1925 to 2011. After it closed, the company began cleaning up the site, with plans to sell the main parcel for redevelopment.

Property associated with the Ford Site

The Ford Site includes two pieces of property:

  • The 122-acre main parcel, where the Twin Cities Assembly Plant was located.
  • The 22-acre river parcel, located west of Mississippi River Boulevard.

The railroad parcel located south of the site once served the Ford Plant. It is owned by the Canadian Pacific Railway and is not part of the Ford Site.

The main parcel has been cleaned up for redevelopment. Ford Motor Company is considering other options for the piece of property along the river. The property contains a steam plant and wastewater treatment plant that served the main assembly plant, and a former dump referred to as “Area C.”

Main parcel

Soil contamination

Some areas of contaminated soil were discovered as building slabs, utilities, and pits were removed. Other areas of soil contamination were identified during the drilling and sampling of soil borings.

The most widespread contaminants of concern found in soil were lead, arsenic, petroleum, and solvents which were used in Ford’s painting operations. Other soil contaminants were present too, in smaller, discrete areas. For example, chlorinated solvents — probably from a metal-cleaning product — were present in soil in the immediate vicinity of a worker pit inside the former main assembly building. Soil along railroad lines was contaminated with wood preservation chemicals from railroad ties.

Soil cleanup

Ford began cleaning up soil contamination on the main parcel in 2015. The largest soil excavations, listed below, went all the way to bedrock, which is at an average depth of about 10 feet at the site:

  • Fill Areas A and B, located southeast of the main assembly building. These areas were used for waste disposal and burning prior to 1960.
  • Arsenic-impacted area, which coincided with the on-site railroad tracks located between the main assembly building and the paint building.
  • Petroleum-impacted area, located beneath the northwest parking lot.

Soil cleanup on the main parcel was completed in June 2018. The figure below shows the areas where contaminated soil was discovered and excavated for landfill disposal. The different colors on the figure just indicate which MPCA-approved cleanup plan guided the excavation.

Map showing contaminated soil at the Ford Plant

Ford chose to clean up soil on the main parcel to the MPCA’s residential standards. By doing so, future redevelopment options for the main parcel will be the most flexible. The role of the MPCA in this process is to make sure that the level of cleanup supports the intended land use.

Although not part of the Ford site, Ford also dug out contaminated soil on a portion of the adjacent rail spur parcel, which is owned by Canadian Pacific Railway. Ford’s former fill areas A and B extended across the property line onto the railway parcel.

Investigation reports, cleanup plans, and cleanup reports, prepared by Ford and reviewed and approved by the MPCA, are available on the city of St. Paul's Ford Site Cleanup webpage and in the MPCA’s project file for the Ford site. The MPCA issued a Certificate of Completion for the main parcel on May 15, 2019, bringing to a close a 12-year effort to prepare the site for redevelopment.

Groundwater contamination

The main contaminants of concern in shallow groundwater on the main parcel are petroleum and solvents which were used in Ford’s painting operations. Areas of shallow contaminated groundwater have been addressed by removing the contaminated soil which caused the problem.

The geology at the Ford site has largely protected the deep, regional aquifer from groundwater contamination. One area of deep groundwater contamination has been identified along the west property boundary, between the former plant and Mississippi River Boulevard. This contamination may be associated with historical nickel plating operations which took place in the western portion of the building before the mid-1970s. Trichloroethene — a metal-cleaning solvent — and metals commonly associated with nickel plating activities (nickel, cobalt, copper, zinc, aluminum) have been detected in two deep monitoring wells in this area. Low concentrations of thallium also appear in these same two wells.

While a contamination source cannot be ruled out, the dissolved metals in deep groundwater may also result in whole or part from a geochemical reaction that is causing naturally-occurring metals in bedrock minerals to be released into the groundwater. Regardless of source, a surface water risk evaluation has demonstrated that the trichloroethene and dissolved metals detected in the deep groundwater do not pose a risk to the Mississippi River. The groundwater contamination does not pose a risk to people. All St. Paul residents get their drinking water from the city's supply system.

Soil vapor

A total of 70 soil vapor samples have been collected at various locations and depths across the main parcel, in a phased approach as soil response actions were completed in different areas. Twelve soil vapor samples contained one or more volatile organic compounds at concentrations that exceeded the MPCA’s action level for residential land use. Based on the site-wide soil vapor investigation, there is not an off-site vapor intrusion risk related to vapor migration from the Ford site.

Additional soil vapor data will be collected as the main parcel is redeveloped, to help inform future building-specific vapor mitigation decisions. The additional soil vapor data will be collected by the developer, prior to construction of site buildings, and under the oversight of the MPCA.

River parcel — Area C


From approximately 1945 through the mid-1960s, Ford disposed of paint sludge and solvents used in automobile painting operations at the base of the bluff. Although the specific disposal practices are not known, it appears that liquid solvents may have been dumped over the edge of the bluff, while barrels of paint sludge were buried. Disposal of industrial waste stopped in about 1966. Ford also disposed of construction rubble, contaminated soil, scrap metal, and other types of debris at Area C. 

During the reconstruction of Lock & Dam No. 1 in the late 1970s and early 1980s,  the U.S. Army Corps of Engineers disposed of a large volume of construction rubble and sand on top of and surrounding the industrial waste. In the mid-1980s, Ford covered the top of the construction rubble pile with a paved parking lot. Additional rubble from a Mississippi River Boulevard road construction project was reportedly placed at Area C in the late 1980s.

Investigation activities at Area C (2015/2016)

Groundwater samples were first collected from Area C in the late 1980s. No significant groundwater contamination was found; however, the investigation was limited, and the MPCA required a more thorough investigation of Area C as part of Ford’s current environmental assessment of its property.

Ford conducted an environmental investigation at Area C in 2015/2016, with results reported in the Area C – Comprehensive Site History and Investigation Report II (Arcadis, May 2017). This report is available on St. Paul’s Ford Site Cleanup webpage.

Key activities and findings included:

  • To determine the size and depth of the industrial waste dump, which is hidden by the overlying construction rubble and fill soil, 10 deep soil borings were drilled through the parking lot which covers Area C. Industrial waste was discovered beneath the eastern half of the parking lot (closest to the bluff). About 40 to 60 feet of fill soil was on top of the industrial waste. The size of the industrial waste dump is shown on Figure 2, below.  The depth of the dump is shown on Figure 3.
  • Five trenches were dug into the south slope of Area C. Two trenches found layers of paint sludge in soil at depths as shallow as 2½ feet. It appeared that the paint sludge had once been in drums, because remnants of crushed drums/scrap metal were found buried close by.
  • The groundwater monitoring network at Area C was expanded to include a total of 11 monitoring wells.
  • Samples of soil, groundwater, and industrial waste were analyzed for a wide variety of potential contaminants.

Map showing layout of Area CThis map of Area C shows the extent of industrial waste. Soil borings through parking lot are gold dots labeled with prefix “ASB.” Groundwater monitoring wells are black-and-white circles labeled with prefix “AMW.”  The green line A-A’ shows the location of the cross-section shown in Figure 3 below.

Graphic showing cross section of Area CFigure 3 shows the layers of material at Area C. If you were to cut Area C in half along the green line A-A’ shown in Figure 2, this is how the different layers would look, when viewed from the side (like a layer cake cut in half).

The blue-dash lines on this figure show the typical elevation of the Mississippi River (lowest line) and river elevations associated with 10-year, 50-year, and 100-year floods.

Soil contamination and waste at Area C

Samples of industrial waste collected from the soil borings and test trenches contained solvents, metals, asphalt-related compounds, and polychlorinated biphenyls (PCBs), all related to Ford’s historical painting operations. The following metals were present at high concentrations in the industrial waste: antimony, arsenic, barium, cadmium, chromium, copper, lead, and zinc. Some samples of industrial waste were found to be hazardous with respect to lead.

The pollutants found in the industrial waste are there for a number of reasons:

  • Solvents found here were added to paint to make it easier to apply.
  • Most of the metals found are associated with different colors of automobile paint from that era, with lead added to increase durability.
  • The earliest automobile paint (black) likely contained liquid asphalt.
  • PCBs may have been added to paint as a plasticizer, to minimize cracking.

Samples collected from the overlying construction fill identified isolated areas impacted by petroleum and asphalt-related contaminants.

Samples of surface soil collected from the slopes of Area C contained low-level petroleum and asphalt-related contaminants, at concentrations typical of urban fill containing road rubble.

Groundwater contamination at Area C

Groundwater near the south slope of Area C shows the highest level of contamination, due to the presence of paint sludge a few feet below ground surface. Rainfall and surface water during floods sinks through the overlying soil in this area and carries pollutants into the groundwater. The main contaminants of concern in this area are painting solvents and petroleum-related compounds.

Other contaminants found in Area C groundwater include low concentrations of cobalt, mercury, cyanide, and asphalt-related compounds. These pollutants occur sporadically in time and/or location and do not indicate a significant plume of contaminated groundwater. For additional information about cyanide and thallium, see Frequently Asked Questions, below.

To determine if the groundwater contamination poses a risk to the Mississippi River, the concentration of pollutants in groundwater is compared to surface water standards that are applicable to the stretch of river near Area C. The evaluation also takes into account site-specific factors such as the volume of contaminated groundwater discharging to the river and the flow rate of the river.

Based on data available to date, the concentrations of pollutants in Area C groundwater are well below levels that pose a risk to the river. Groundwater monitoring is ongoing at Area C, and the surface water evaluation will be updated as needed based on new information.

Groundwater monitoring (2017–2019)

After reviewing the May 2017 Area C report, the MPCA asked Ford to gather additional groundwater data to evaluate how the water table at Area C fluctuates in response to changing river conditions. Continuous water-level recording devices were installed in five monitoring wells. The water level data show that when the river level rises during flood events, the groundwater below Area C rises into the industrial waste (see Figure 3, above).

Ford has continued to collect groundwater samples from Area C monitoring wells on a quarterly basis, with additional sampling events triggered by flood conditions. During and after flood events, until water levels return to normal stage, Ford collects monthly groundwater samples from the Area C monitoring wells. Groundwater quality data collected during the 2017 to 2019 sampling events has been largely consistent with earlier data, as described above.

Health assessment for Area C

The MPCA asked the Minnesota Department of Health (MDH) to do an independent review of potential risk to public health posed by the Area C dump.

The conclusions and recommendations presented in the memo are as follows:

“MDH concludes that there are only very limited ways that people can come into contact with the contamination at Area C. The presence of waste buried at Area C does not mean people have been or will be exposed to a health hazard. Our assessment found that minimal risks are possible if trespassers directly contact contaminants in shallow soils and physical hazards. Other exposure pathways were considered, but none were found to be complete.

MDH recommendations:

  • To discourage trespassing, consider repairing the fence and adding signage between the Hidden Falls Regional Park walking trail and the southern boundary of Area C.
  • Consider removal of potential physical hazards and soil contamination from the southern slope.
  • Continue monitoring the groundwater to demonstrate the ongoing negligible impact of any contamination moving from Area C to the Mississippi River via the groundwater pathway."

The MDH document is an assessment of potential risk to people given the current condition of Area C. Members of the community who have expressed concerns about risk to public health may find the MDH document to be helpful. The absence of significant risk to public health under current conditions does not mean that no cleanup is warranted at Area C.

Next steps for Area C

  • Several additional monitoring wells will be installed around Area C in 2020, including wells in the St. Peter bedrock aquifer, to ensure that any groundwater contamination caused by Area C has been identified.
  • As a precautionary measure, Ford will analyze groundwater samples at Area C for perfluoroalkyl and polyfluoroalkyl substances (PFAS). Because Ford’s historical operations included a metal plating operation, it’s possible that a vapor suppression foam containing PFAS may have been used in the main plant building prior to the mid-1970s. There is no evidence at this time that metal plating wastes were disposed of at Area C. The paint waste and solvents disposed of at Area C do not contain PFAS.
  • A cleanup plan has not been selected for Area C. The MPCA has requested that Ford evaluate a number of cleanup alternatives, to be presented in a pending document called a Feasibility Study. The Feasibility Study will not be submitted until the groundwater investigation at Area C has been completed.

Frequently asked questions

Yes, Ford chose to clean up soil on the main parcel to meet the MPCA’s residential use criteria. However, specific land use decisions by property owners and local units of government also take into account other considerations, such as economics, business risk, and urban planning. The MPCA is not involved in land use decisions.

Thallium is a metal that occurs naturally in the earth’s crust. It enters the environment primarily from air emissions from the combustion of coal and from mineral smelters. Thallium is used in a limited number of manufacturing operations, but it is not a pollutant that is typically associated with the automobile industry. Testing of industrial waste samples collected during the Area C investigation did not identify thallium as a contaminant of concern in the industrial waste.

Low concentrations of thallium were initially thought to be present in Area C groundwater, based largely on sampling done in 2016. Because this seemed at odds with what is known about the sources of thallium and the wider body of information available for the Ford Site, the MPCA asked Ford to analyze future groundwater samples using a different testing method — one that is known for producing more accurate and reliable thallium data.

Thallium has not been detected in the majority of groundwater samples collected from Area C monitoring wells during follow-up sampling. Groundwater samples continue to be analyzed for thallium as part of a standard grouping of metals run by the laboratory, so additional data is being gathered.

Low concentrations of cyanide have been sporadically detected in a few monitoring wells, at levels below drinking water standards and also below levels that pose a risk to the Mississippi River. The cyanide is likely associated with blue paint, which derived its color from an iron-cyanide compound. The iron-cyanide compound is typically stable in the environment and doesn’t release “free” cyanide to the groundwater, which is the harmful form of cyanide. Based on data available to date, cyanide is not a significant contaminant of concern in Area C groundwater.

Ford Site contacts

If you have a question about the environmental investigation or cleanup of the Ford Site, call or email one of the MPCA contacts listed below.

Amy Hadiaris, P.G.

Shanna Schmitt, P.G.