Madison/Truax Field Thumbnail
The history of contamination at Truax is discussed by Maria Powell here. As with many sites contaminated with PFAS by use of fire fighting foam, there is a previous investigation of contamination by chlorinated volatile organic compounds (CVOC or VOC). Madison municipal well 15 was equipped with an air stripper to remove them. The big picture is displayed in her map. It does not include the affected municipal wells, which are discussed below under heading Receptors.

What we know as of 4/2022
Mistakes we've seen (well, besides at least a decade of foot-dragging)
Things we strongly suspect but which have not yet been confirmed

Source Zones
02-13-581254 WANG-115TH FIGHTER WING
WIANG source zone results
20211223_35_SIWP2.pdf PDF p. 80 fig 10-8
Soil and groundwater results for the Air National Guard base only - does not include old burn pits on Darwin Rd & Pearson St (see below)

original documents
20170831_35_SIWP.pdf site investigation workplan
samples taken 11/08/17
20190711_37_SIR.pdf    Final Phase I site investigation report (Amec Foster Wheeler 2019) and are summarized in
results displayed in a map on PDF p. 80 - 85, Figs 4-9
20200306_35_SIWP.pdf site investigation workplan for Darwin and Pearson burn pits.
20201215_120_PFAS_Sampling_Completed.pdf Former Firefighting Training Areas Soil and Groundwater Sampling Summary, Mead & Hunt, Inc./LimnoTech dated 11/2020
PDF file pp 7-10, Figures 1 through 4 show reported PFOA and PFOS results for soil and groundwater samples
Documented Routes Off Base
Via groundwater to well 15
This situation is reminiscent of Oakfield, MN municipal well 5, the well most heavily contaminated by the 3M disposal site, discussed in detail in this chapter.
Through the airport storm sewer network to Starkweather Creek
The current theory is that a shallow groundwater table allows highly contaminated groundwater to infiltrate into the storm sewers which carry it to outfalls in the branches of Starkweather Creek that drain the airport
In the stormwater chapter I have summarized the testing in Starkweather Creek and Lake Monona, at the storm sewer outfalls and at a few major junctions in the storm sewer network. In May 2021 there was an extensive video inspection of the storm sewers in the area around the WI Air National Guard (WIANG) base. I also did an engineering critique of local efforts to operate a filter intended to remove PFAS from the stormwater.
Through the food chain via fish
In June 2021 the fish advisory for Starkweather Creek, Lake Monona and the Yahara River was extended to the Rock River.
Madison Municipal Wells (and a few private wells)
After a lot of pushing from local environmental activists the Madison Water Utility tested all of its wells in 2019 and has done so annually since. In this chapter I (mostly) used the 2020 numbers to examine the composition of PFAS across the wells, concluding that it is consistent with AFFF. Three of the wells appear to be impacted by Truax. The others may well have been contaminated by the Madison Fire Department which for decades has used foam to extinguish vehicle fires. I reference separate chapters suggesting that surface water transport is important in spreading PFAS more widely within the city, and explaining why the usual groundwater models are inadequate to estimate the extent of PFAS groundwater plumes and inversely to locate their source.

In 2020/2021 the utility contracted for a PFAS treatment feasibility study. They initially proposed to wait on the well 15 decision until DNR promulgated standards. After community feedback they modified their stance, stating that they would use the stricter WI DHS hazard index which takes into account PFAS other then PFOS & PFOS and which well 15 exceeds. In the Town of Campbell near the La Crosse airport anyone with a DHS hazard index > 1 gets bottled water.

There are systemic issues that should be addressed. The water utility technical advisory committee lacks  PFAS expertise. Public input consisting of a utility-wide 'info' email address which elicits no response is insufficient.

Public messaging by the city should make less use of trite phrases like 'speak with one voice' and more discussion of the published toxicology research that underlies attempts to set health levels.
Site Investigation Workplan Summary
On 1/11/2022 the National Guard Bureau gave an 'open house' presentation of the workplan, which is available on the DNR BRRTS page titled 02-13-581254 WANG-115TH FIGHTER WING. The workplan is split into three documents, including 20211223_35_SIWP2.pdf (information specific to Truax) and 20211223_35_SIWP.pdf (information common to all three sites covered by the contract).

The goals as stated in 20211223_35_SIWP2.pdf include:
2280 • Determine the extent of PFAS at or above RI [remedial investigation] SLs [screening levels] (Worksheet #15) at sources and in all
2281 pathways at Truax Field.

2285 • Determine the concentration of PFOA, PFOS, and PFBS at or above SLs
2286 (Worksheet #15) in soil, groundwater, surface water, vadose zone porewater, and
2287 sediment, both in source areas and all pathways, to establish concentration gradients.
The most important takeaways consist of the list of specific contaminants considered and the screening levels at which they are considered significant.
1972 The quantitative human health risk assessment will be limited to three of the PFAS—PFOS,
1973 PFOA, and PFBS—for water samples (groundwater and surface water) per U.S. Air Force
1974 guidance. Additional PFAS may be included in the assessment if toxicity values become
1975 available during the project.

20211223_35_SIWP.pdf PDF p. 41 (ca line 982)
QAPP Worksheet #15-1: Project Screening Levels and Laboratory-Specific Detection/Quantitation Limits

Analyte                                 Acronym    CAS           SL (ng/l)
Perfluorobutane sulfonate    PFBS          375-73-5    600
Perfluorooctane sulfonate    PFOS          1763-23-1  40
Perfluorooctanoic acid         PFOA         335-67-1    40
note: no screening level for PFHxS
These screening levels are well above the WI DHS proposed health levels. The most contaminated municipal well along with the contaminated private well would not merit consideration. This is true even though EPA toxicologists have recently signaled that this level is inadequate.

At the 1/11/2022 Open House, Environmental Restoration Program Manager Bill Myer stated that state regulations would be considered, but only if they have been promulgated. That is very unlikely given the level of control that WMC has over both the DNR board and the state legislative committees.

While the site investigation is unlikely to define the full extent of the contamination, it will generate considerable information regarding the source areas and suggest how it is entering Starkweather Creek.

The consultants made some observations about the conditions at Truax and how they might influence PFAS transport off the base
1883 Truax Field-Specific Fate and Transport Considerations
1885 • The presence of organic-rich marshy deposits has particular significance for retention of
1886 PFAS mass in source areas.
1888 • PRLs 1, 2, and 3 are on the western portion of Truax Field and located closest to potential
1889 surface water migration pathways. Additional potential sources identified in Sections
1890 10.9.2 and 10.9.3 are also located near potentially downgradient surface water migration
1891 pathways.
1915 • The shallow depth to groundwater at the Base, presence of marshy deposits, and low
1916 permeability of underlying glacial deposits are good indicators that vertical migration
1917 pathways for the plume may be limited. However, historic maps indicate that the marshy
1918 deposits are absent in potentially downgradient directions.
In addition, if the groundwater flow is indeed toward the southeast it seems likely that the contamination is being carried away from Starkweather Creek, toward well 15. These factors raise the possibility that the storm sewers are the primary route for contaminants to enter Starkweather Creek, and that the proposed repairs might result in a large reduction. We can only hope.

The gory details of the geology and methods will mostly be pushed into a separate chapter but there are some highlights worth listing here.

It may be best to start by looking at Fig 17-1 thru 17-8, which start on p. 112 of the PDF file 20211223_35_SIWP2.pdf:
Figure                                                       Discussion page no.
17-1 transects                                           88, 103-106
17-2 crash site                                          104, 105
17-3 surface/storm/sediment samples      90, 106
17-4 background samples                        104
17-5 PRLs 4, 5, 6                                    104
17-6 PRLs 8, 9                                            104
17-7 PRLs 1,2, 3, 7***                               104
17-8 PRL 10                                               104

***note that PRLs 1-3 are the fire station and its associated nozzle test areas, the most contaminated part of the base
The sampling approach is discussed on PDF file p. 103 (line 2813). The term 'transect' will be discussed in the geology & methods chapter. The two paragraphs beginning at line 2833 merit an explanation here.
2833 Data generated during the RI will be a combination of definitive analytical results and
2834 quantitative screening analytical results.
"Definitive analytical results" are generated by shipping samples to a traditional laboratory. "Quantitative screening analytical results" are generated by processing samples on-site in a mobile laboratory. The mobile lab is the result of a SERDP/ESTCP project, the results of which were published.

The mobile lab achieves rapid sample throughput  both by eliminating shipping delays and by using a reduced set of PFAS analytes, basically the three compounds for which screening levels are established. This allows for high resolution plotting of the plumes and quick decisions in the field on where to sample next. When a particular sample requires a more accurate determination for comparison with a screening or health limit or if a full set of analytes is desired, part of the sample is shipped to the traditional laboratory. There is further discussion of the mobile lab on PDF file p. 162.

PDF p. 95 (line 2543) is the projected work schedule

It is also worth noting that the consultants propose to use the TOP assay on a subset of samples, mentioning it at lines 2340 [soil], 2438 [unspecified] and 2882 [soil].
This should provide an upper limit for the amount of precursors which do not show up in the analytical results discussed above.

Jennifer Field has
noted that quadrupole time of flight (QTOF) analysis of samples from AFFF sites show "missing mass",  usually only 10-15% of the total but occasionally up to a third.

Jennifer Field QTOF missing mass typical

        Field QTOF missing mass max

In my comments on the workplan I noted that well 15 has several characteristics which suggest the presence of significant precursors and recommended a TOP assay on the groundwater in the plume.

Lines 2340 and 2882 say that the TOP assay will be used for a subset of soil samples. Line 2438 also mentions the TOP assay but is ambiguous as to which media are involved.

Well 15 has multiple characteristics that suggest the presence of precursors:

Significant levels of undetected precursors could result in underestimation of effective PFOS+PFOA levels. For this reason some have recommended use of the TOP assay for drinking water to “quantify presence of perfluoroalkyl compound precursors in the supply”.

Understanding the Uses and Limitations of TOP Assay for PFAS Monitoring in Drinking Water- Rebecca Slabaugh referenced in

PDF p. 33 (line 703) discusses previous investigations, which are listed in worksheet 13 on PDF p. 93 (line 2518).

PDF p. 106 line 2961    storm sewer (references fig 17-3)
            table 17-1 summarizes results of video examination of sewer condition

PDF p. 21-31 lists the organizations and personnel involved in the site investigation
The division of responsibilities is awkward because the DNR has identified three responsible parties: