The PFAS Site Investigation Workplan mentioned activities during 2010 and 1994, so I searched BRRTS
Municipality = La Crosse; Substance = VOC

22 results: looking around 2010...

02-32-000065 LA CROSSE MUNICIPAL WELLS 23 & 24
Note: these are the same wells shut down in 2019 for PFAS

The only individual document available for download is from 2010: 20100505_11_Closure_Final.pdf
Final case closure and grant of NR 140 exemption for the City of La Crosse's Municipal Well 23H & 24H Remediation Project on French Island...
"Recent groundwater monitoring data at this site indicates that for trichloroethylene at MW-11l contaminant levels exceed the NR 140 preventive action limit (PAL) but are below the enforcement standard (ES.
        The department may grant an exemption...if all of the following criteria are met:
            (1) The measured or anticipated increase in the concentration of the trichloroethylene will be minimized to the extent technically and economically feasible
            ...
        Based on the information you provided, the Department believes that these criteria have been or will be met.

Case reopened in 2019 due to PFAS, but that was then transferred to a new case (see above)

I then noticed the 'site file' which is apparently a compilation of all the older stuff into two files
0232000065_SITE_FILE_1978_THRU_1994.PDF (200 mb)

Near the top of the file is correspondence

12/28/1994

12/23/1994 it was agreed upon that the best approach would be to install an interceptor well upgradient of the municipal well 23. The objective would be to intercept the plume and remove the contaminated portion of the aquifer before it would reach well 23.

12/22/1994

11/4/1994;

PDF p. 20 RMT report "Additional Investigation Activities, Treatability Studies, and Remedial Options Analysis (1994)."

I skimmed this report, paying more attention to the portions that described the VOC plume, how they located it and suggestions for remediation.
Below are the parts I found most interesting.

PDF p. 25 map showing burn pit & wells 23/24. Nearer well (24H) is about 3000' SE of the test burn pits.
PDF p. 26

The results of this investigation were that the VOC plume was relatively narrow (approximately 200 feet wide) and extended from the former burn pits to the municipal wells. The extent and degree of the contaminant. plume were not well defined though because most of the wells were installed outside of the zone of groundwater contamination (LGI, 1993).

Groundwater samples were collected at 10-foot intervals using a slotted lead auger as the borings were advanced.
The water samples were analyzed in the field for VOCs using a portable gas chromatograph (GC).
Results of the in-field analysis were used to locate monitoring well nest MW-11 S/MW-111/MW-11 D within the contaminant plume.

The groundwater flow direction across the study area is generally to the southeast, toward the Black River.

These geologic cross sections also contain TCE concentration contours, which are referred to in Subsection 3.3.

One of the new water table wells (MW-8) was installed upgradient of the
former burn pits to establish background groundwater quality. Three water table wells and
three piezometers were installed approximately 0.5 mile downgradient of the former burn pits
to monitor shallow and deep groundwater quality near City wells 23H and 24H.

PDF p. 32    cross-section including TCE plume

On the basis of the results of the in-field analysis of groundwater samples from the
four soil borings, well nest MW-11 S/MW-111/MW-11 D was installed near boring TH-3, which is
believed to be near the center of the VOC plume.

The results of the groundwater portable GC analysis are summarized in Table 3.

PDF p. 39 Table 3

further discussion of placement of RW-1 groundwater extraction well 'upstream' of 24H

mentions of RW-1 ("interceptor" well) in the report:
    p. 50;
==>    PDF p. 73 shows plume map and locations of wells
    PDF p. 297