https://www.cityoflacrosse.org/city-services/private-potable-well-sampling-for-pfas
https://townofcampbell.org/well-water-pfas-information/

Scroll down this page to see a map which shows four major plumes - listed from NE to SW:

1. test burn pits
2. former fire station/nozzle test area
3. terminal apron (multiple incidents - see below)
4. 2001 crash site
   

https://dnr.wisconsin.gov/topic/PFAS/Campbell.html includes links to DNR BRRTS activity page (below)

About this site

DNR BRRTS web pages:
02-32-587347 LA CROSSE AIRPORT PFAS INVESTIGATION

02-32-587311 TOWN OF CAMPBELL PFAS INVESTIGATION

Summary

• As in Madison and Eau Claire  the discovery of PFAS contamination at the airport was foreshadowed by an earlier investigation of VOC contamination. This contamination originated in the burn pits and was carried southeast to two municipal wells along the eastern edge of French Island. The PFAS contamination tended to follow the same path.

• The consultants concluded that the plume leading southeast from the 2001 crash site into a residential neighborhood is the responsibility of the City of La Crosse which owns the airport. However they claim that contamination in the residential area west of Airport comes from an unknown source (which they have made no real attempt to identify) and that the contamination could not come from a known source due to strong groundwater southeasterly flow. For the same reason they said in their 10/20/2021 update that well 26 was not a possible receptor. It tested positive the following spring. They do not attempt to explain the pattern in contamination of private wells in the Del Ray Ave neighborhood, where wells close to Airport Road are highly contaminated and levels fall off toward the west.
  

•  PFAS in the Del Ray Ave area west of Airport Road was presumed to come from an unknown source. By a remarkable coincidence, its composition appears to match a simple mixture of the two nearest confirmed sources: the high-sulfonate 2001 crash site and the high-PFOA terminal apron. The same mixing appears to occur at a different ratio in the 'shadow' plume SW of the main plume from the 2001 crash, whose extrapolation to the NW would lead to the Del Ray Ave area. The area around the 1970 crash also seems to have received some of its PFAS from a high-PFOA source.

• UW Geoscience Professor Michael Cardiff said that he believes the groundwater model used by the consultants does not account for recharge on the island and water movement may be influenced by private wells west of Airport Road and by water table mounding, which would be expected in three areas in the airport:

(1) west of the main runway and clearly visible as a dark green oval on the Google maps satellite image between the Del Ray Avenue area and the junction of the main north/south and NE/SW runways

(2) near the intersection of Fanta Reed Rd and Dawson Ave, also noticeably greener than its surroundings on the satellite image, serving the area east of the main north/south runway.

(3) along the north shore of French Island roughly half way between Lakeshore Drive and the main north/south runway.

• These were mentioned as potential source areas in the interim site investigation report section 9.2.7 Areas of Stormwater Infiltration. It is unclear why they have not been sampled.

• PFAS from the terminal apron was apparently transported along the surface and via culverts to the west infiltration area where groundwater mounding plus the effect of private wells would have pushed some of it west to Del Ray Ave .
  

• While the connection is less obvious, there is a storm sewer which serves a parking lot adjoining the southwest corner of the terminal apron which runs north to the stormwater retention pond near the site of the 1970 crash. High PFOA levels are detected in private wells there. This sewer also passes within feet of contaminated well 26.
  

• PFAS from the 2001 crash site would also tend to be pushed west by episodic mounding in the east infiltration area. This might explain the apparent appearance of multiple parallel plumes SSE of the 2001 crash site, in addition to the sulfonate contamination in the Del Ray Ave area.

Recommendations

• Water level data in both southern infiltration areas as well as in the Del Ray Ave area after heavy rain and flood events would help to clarify movement in the water table. Sampling in the infiltration areas could confirm PFAS surface and storm sewer transport from the terminal apron and possibly from the large apron in front of the fire station.
  

• The USGS/WGNHS groundwater model used by the consultants provides a lot of useful information. However, it is a steady state model not designed to account for highly dynamic situations like the 2023 spring flood or especially heavy rain events. It was calibrated to cover an area of 30 miles by 30 miles and the developers warn against attempting to use it to simulate local behavior. Transient modeling of the airport vicinity which accounts for private wells and groundwater mounding and which uses boundary conditions that reflect spring flooding might explain the observed behavior.
  

Site Investigation

Results of the PFAS interim investigation are found in two files on the DNR BRRTS page:

INTERIM SIR (Site Investigation Report) WITH APPENDICES    20210407_43_Interim_SIR.pdf

Results of soil and groundwater sampling of the known source zones. While the report is fairly complete for interim work, the analysis and conclusions rely heavily on groundwater modeling which has been problematic in general.

20210804_43_PW_Sample_Results.pdf

Results of sampling of private wells to the south and west of the airport.

Context

Private well results from the area south and west of the airport are detailed in 20210804_43_PW_Sample_Results.pdf with a map in Fig 3a (PDF file p 80) .

The consultant for the City of La Crosse has acknowledged responsibility for contamination southeast of the 2001 crash site. This area is depicted in greater detail in Figure 3d of the sample results report.

The city's consultant denies responsibility for contamination west of the 2001 crash site, in the area depicted in Figure 3c, with homes on the east side of Del Ray Ave outlined in light blue. They claim that groundwater modeling indicates that the prevailing groundwater flows southeast under the influence of the dams on either side of the island.

Comparison of PFAS composition in the various areas as well as the pattern in the results suggest otherwise. We will deal with these issues one at a time in a separate page. You may wish to keep this page open in a separate browser window since there are many references to the image above.