Firefighters spray PFAS-containing foam on exploded transformer at the Madison Gas & Electric Blount St. station in Madison, summer 2019 (Photo by Wisconsin State Journal)
On July 19, 2019 an American Transmission Company (ATC) transformer at the Madison Gas & Electric Blount Sreet substation exploded and burned, leading to widespread power outages on a very hot summer day.
Firefighters from the Madison Fire Department and Truax Air National Guard used firefighting foam containing the highly toxic forever chemicals called PFAS. The foam went down stormdrains all around MGE and into Lake Monona, less than 1/2 mile away.
Testing on the day of the fire and several days later showed significant levels of PFAS in groundwater and stormwater at the site and at storm outlets in Lake Monona at Law Park and the Elk’s Club.
Many shoreline anglers, including low income subsistence anglers of color, fish at these locations. PFAS can build up to levels hundreds and thousands of times higher in fish tissue than in water. Nothing was done in 2019 to warn anglers there of the risks–and nothing has been done to inform them since then.
See our 2019 posts here and here, and local news articles here and here.
Below: Law Park stormwater outlet into Lake Monona in 2019, with yellow boom installed to prevent PFAS foam from spreading after the MGE fire (Photo by Maria Powell)
Did remediation at MGE work?
Since summer 2019, various attempts were made–some successful, some not–to suck up and treat PFAS from the groundwater, surface water, and stormwater at the site. Contaminated soils were removed from hotspots. For details about these efforts, see the documents on the DNR’s Bureau for Redevelopment & Remediation Tracking System (BRRTS) site.
Did these remedial strategies work? Is there less PFAS in the groundwater and surface water at MGE now? Less PFAS at storm outlets in Lake Monona?
Sadly, no. The December 10, 2020 consultant (AECOM) report shows that from spring through fall 2020–over a year after the fire–levels of PFAS in groundwater under MGE and at the stormwater outlets to Lake Monona weren’t much different than they were in summer 2019 after the fire, and in some places were higher.
In the 2020 testing, levels of PFOS at Lake Monona stormwater outlets were up to 16 ppt–8 times over the DNR’s proposed surface water standard of 2 ppt for this compound. [1] These levels are about the same as those found in 2019.
At MGE, total PFAS levels in 2020 testing were up to 12,000 ppt in groundwater and 980 ppt in stormwater, both higher than levels measured in 2019 (up to 9300 ppt and 710 ppt respectively). The PFAS compound found at the highest levels was 6:2 FTS (fluorotelomer sulphonate), an unregulated compound that was used to replace PFOS and PFOA in firefighting foams and other applications.
The groundwater samples were from a sump pump called the “Trans Sump” that draws ground water from under the site, which according to the consultant report, is connected to the city storm sewer system. The stormwater samples were from a “Storm Ceptor” that captures stormwater from the site and also drains to city storm sewers.
There is no groundwater standard for total PFAS, but DHS recently proposed a 20 ppt groundwater standard for six PFAS compounds combined. This standard doesn’t include 6:2 FTS. Even without counting 6:2 FTS, the 2020 PFAS levels for the six compounds in the groundwater sump were up to 55 ppt, almost twice the levels measured in 2019 (29 ppt) [2]
Groundwater, storm and surface water on the Isthmus (a filled wetland with groundwater just 3-5 feet below the surface, and higher when it rains a lot) fluctuate up and down with changes in rainfall, groundwater levels, and lake levels. PFAS levels will also vary along with these fluctuations.
Regardless, give or take some variations, PFAS levels in 2020 at key sampling points were about the same and in some cases much higher than levels found there in 2019.
ATC is asking DNR for no further action and site closure
So what is ATC proposing to do next? On their client’s behalf, ATC’s consultants propose that DNR issue a “no further action” letter (a step toward site closure), based on the following arguments:
- The PFAS concentrations in water samples at the MGE site no longer exceed the recently proposed Chapter NR 140 Enforcement Standards for PFAS.
- The PFAS in surface and groundwater at the site is not migrating offsite
- The PFAS found offsite and at the stormwater outlets to Lake Monona reflects “background” levels.
ATC concludes that “Based on these findings, the residual PFAS impacts are not believed to pose an unacceptable risk to receptors via direct contact, vapor, or groundwater.” [3]
Should DNR accept ATC’s arguments? No
Argument #1 is incorrect and disingenuous. Though the very last 2020 onsite groundwater test at the “Trans Sump” found PFAS levels of 19 ppt, 1 ppt below the proposed 6 compound standard of 20 ppt, the previous test found 55 ppt. All but the last surface water sample at the onsite “Storm Ceptor” exceeded the DNR’s proposed surface water standard of 2 ppt (and this data point is meaningless because the detection limit was 5.5 ppt, over the standard).
Again, the MGE site is a filled wetland where groundwater is practically at the surface. In fact, the consultant report states: “The City’ storm sewer system is regularly surcharged throughout this area of the isthmus, which through granular backfill and leaky sewer pipes provides direct communication with the area’s surface water bodies.” (emphasis added)
Given the above, during and after the fire the PFAS contamination in groundwater and stormwater at MGE definitely seeped immediately into groundwater traveling radially away from the site and rushed through storm drains leading to Lake Monona. The PFAS in groundwater remaining at the site now continues to do so, though levels are diluted by stormwater, groundwater, and lake water as they rise, fall, and slosh back and forth through the Isthmus.
Are PFAS levels at the lake “background” levels?
AECOM’s arguments that PFAS levels off the MGE site are “background” are based on problematic comparisons and raise more questions than answers.
In part, consultants support their argument that PFAS did not migrate offsite with onsite vs offsite PFAS level comparisons. They did not consider the fact that the thick, heavy smoke from the fire, which included burned-up PFAS (see photo below) dispersed and deposited onto soils and surface water onsite and offsite, muddying comparisons between the site and “background” (offsite).
Also, AECOM also used 6:2 FTS (fluorotelomer sulphonate) as the “indicator compound in water,” arguing that because it is found onsite at high levels, but not at the storm sewer outlets to the lakes, it is not from MGE. Apparently these consultants are unaware that 6:2 FTS, 10:2 FTS, and other longer-chain telomers in firefighting foams (including some not assessed with the type of analytical method used to analyze the firefighting foams used at MGE), break down very quickly in the environment, transforming into many other shorter-chain PFAS compounds that were found onsite and offsite.
Moreover, common sense prompts questions about the background argument. In this context, what does “background” mean? The PFOS and PFOA levels found at lake outlets were higher than levels found in the middle of Lake Monona in the data recently released by DNR–and significantly higher than levels found in Lake Mendota and Wingra. If these are normal background levels for this area, wouldn’t all the lakes have similar levels?
High levels of PFAS remain under MGE and at Lake Monona storm outlets. Shouldn’t we publicly discuss this?
Questions and uncertainties notwithstanding, the ATC consultants’ report shows that significant amounts of PFAS currently remain under MGE. Science and common sense indicate that this PFAS is oozing, draining, and sloshing into Lake Monona. Levels of PFOS at Lake Monona storm outlets are well over the DNR’s proposed surface water standard of 2 ppt.
The argument that the PFAS at the Lake Monona storm water outlets is “background,” even if true, only begs another critical question: If this PFAS is not from MGE, then where did it come from? There may well be other PFAS sources on the Isthmus adding to the PFAS sloshing into the lakes from MGE. If so, shouldn’t we locate and address them?
Given the questions outlined above, and recent PFAS findings in the Yahara lakes, it would be an outrage if DNR quietly issued closure for this site without open and robust discussions with city leaders, scientific experts, and the public about the PFAS remaining at MGE and its environmental and public health implications.
[2] Unfortunately, 6:2 FTS is not regulated and is not included in DHS’s recently proposed standards, even though it is a key ingredient in many currently used firefighting foams and was in the foams used on the MGE fire. ATC’s consultants downplay concerns about the health risks of this compound, saying: “Although 6:2 FTS is currently unregulated, toxicological studies that have been done suggest 6:2 FTS may be less toxic than PFOA or PFOS. For example, an April 2020 ITRC report says, “6:2 FTS toxicity was found to be less than that for either PFOS or PFOA in the same study [of terrestrial invertebrates].” This compound and other telomers were used to replace PFOA, PFOS, and other longer chaing compounds when they were regulated. As more studies are done on it, evidence is building that is likely as toxic as the others.
[3] Here’s an excerpt from the executive summary:
“Based on site investigation results, the primary PFAS constituent of the AFFF product is 6:2 FTS. Following removal actions, only low levels of residual 6:2 FTS and other PFAS analytes remain in soils at the substation. Overall, the average total PFAS concentration of residual surface soils inside the substation is lower than the apparent background PFAS concentrations outside the substation walls. Using 6:2 FTS as the indicator compound in water, PFAS does not appear to be migrating from the substation and observed PFAS concentrations outside the substation are not likely related to the AFFF release.
Furthermore, PFAS concentrations in water samples at the site no longer exceed the recently proposed Chapter NR 140 Enforcement Standards for PFAS.”
Therefore, the site investigation has successfully characterized the residual PFAS-impacts related to the release of AFFF product in response to the transformer fire on July 19, 2019. The primary component of the AFFF is 6:2 FTS, which was used to guide remedial efforts and also to distinguish AFFF impacts from background PFAS-impacts that were characterized by a higher occurrence of PFOA and PFOS not found at the substation. Extensive source removal at the site has removed to the extent practical PFAS-impacted soil and water related to the AFFF release. Based on these findings, the residual PFAS impacts are not believed to pose an unacceptable risk to receptors via direct contact, vapor, or groundwater.”
PFAS spilled into Lake Monona after MGE fire; Did anyone test fish? Or warn anglers?
PFAS traveled from MGE to Lake Monona after July fire; DNR says there may be other sources
