Plan Commission Minutes
Town of Washburn
Section 29 Closed Landfill, South Maple Hill Rd.
Sunday, October 16, 2022
Members present: Kim Bro (chair), Cyndi Belanger (secretary), Tim Schwenzfeier (vice chair).
Members absent: Jim Park (town board representative), Hallie Sandberg.
Others present: Bob Adams, Scott Kluver (Washburn City Administrator) , Bob Short, Wendy
1. Chairman Bro called the meeting of the commission to order at 3:30 P.M. and verified its
legal notification (posted at town hall and Tetzner Dairy) on October 11, 2022 and on town
2. The commission led a field visit of the closed landfill to explain – and learn – the historical
operation and closure process, groundwater monitoring, and post-closure maintenance. Some
of those present disposed their garbage at the landfill when it was open and shared
recollections of its operation. The group observed areas of subsidence subsequent to closure.
Kim shared a drawing the proposed operation of the landfill from 1974 and a conceptual
cross-sectional view of the closed landfill’s current condition. The landfill operated as a series
of north-south trenches in the sandy soil approximately 500 feet long, 20 feet wide and 10 feet
deep. Trenches were excavated sequentially from west to east. As one trench was excavated
and filled with solid waste, it was compacted and covered with two feet of sand, and the next
trench was excavated to the east and filled. Municipal solid waste was disposed in the
trenches for 15 years from 1975 through 1989. There is no impervious barrier at the bottoms
of the trenches. Any leachate leaking from the waste seeps into the sandy soil below. The
bottoms of the trenches are approximately 250 feet above the groundwater table.
Kim shared two figures comparing the topography of the landfill cap in 1990 vs 2020. What
were smooth contours with a drainage swale in the east third of the cap is now much more
“lumpy,” likely from the decay and compaction of municipal solid waste below the cap. The
most severe such depressions are on the east side of the landfill. They subsided at least two
feet. The cattails growing in them is an indication that they form ponds of standing water for a
substantial part of the year. Surface water flows to the north, and groundwater flows to the
east toward Lake Superior. The elevation of the water table in Monitoring Well #1 (on the
west) is approximately 3 feet higher than that in Monitoring Well #3 (on the east) and
approximately 1 foot higher than Monitoring Well #2 (to the south).
Kim explained how a clay cap functions. Clay is not impervious but rather is very weakly
permeable. Surface water flows through the clay and into the buried waste, but the clay is
expected to minimize the rate of leachate flowing into the groundwater so that concentrations
of landfill contaminants in groundwater will
remain low as the groundwater flows east away
from the landfill site. The six-inch cover of
topsoil over the clay cap provides a medium
for grassy groundcover that prevents erosion of
the clay cap and it is contoured to direct
surface water flow off of the cap without
flowing so fast that gullies are formed. The
topsoil cover is intended to hold enough
moisture to reduce the likelihood of the clay
drying and cracking. Any cracks in the clay
are potential conduits that carry larger amounts
of surface water into the waste and increase the
rate of leachate flow to groundwater.
Regular mowing of vegetation on the cap is intended to minimize the potential for deeprooted vegetation from penetrating the cap and creating additional conduits for water to seep
into the waste too rapidly. As solid waste under the cap decays and becomes more compacted,
the clay cap will subside. These areas of subsidence may reduce the rate of surface water
runoff and may even allow water to pool over the clay. These lumps and pools on the surface
of the cap increase the rate of leachate seeping into the groundwater. Cracks in the clay may
also occur around areas of subsidence. The groups saw several cracks in the soil around these
depressions, but it was not clear that the cracks extended through the clay cap.
Other potential sources of damage to a cap are 1) vehicle traffic that may cause ruts in the
surface, 2) deposition of rocks, boulders, or other debris, and holes created by burrowing
animals. The group could only guess where the boundaries of the clay cap are and
recommended that testing with small soil cores be done to prevent encroachment and
disturbance of the cap and to assure that the entire cap area is mowed.
Cattail depression in clay cap.
Kim had compiled groundwater sampling data from the Wisconsin Department of Natural
Resources online database of landfill groundwater data (GEMS) and showed two graphs to
illustrate how landfill leachate is affecting groundwater. Scott mentioned that sampling
recently occurred in September, and Kim added the data Scott shared to the graphs shown
Chloride concentrations are a general indicator of the “saltiness” of the water. At a few parts
per million (mg/L), it is not a substance of health concern but rather indicates that landfill
leachate is in groundwater. It is not detectable in the “upstream” well (#1) on the east, but
started to be detectable in the “downstream” well (#3) in 2003. Concentrations rose steadily to
a peak of 26 mg/L in 2013 and now are leveling to approximately 20 mg/L recently. Kim said,
to think of a leachate plume, as a trickle of colored water in a slowly flowing stream: the color
spreads and fades as the colored liquid diffuses and slowly flows downstream. It took several
years after waste was placed in the landfill for the salty leachate to be detectable in Well #3.
Six organic solvents have been detected in the “downstream” well (#3), but only one solvent
occurs at levels that can be quantified in laboratory tests: tetrahydrofuran. The Wisconsin
Groundwater Standard for tetrahydrofuran is 50 parts per billion (µg/L), and the Wisconsin
Preventive Action Limit is 10 µg/L. Kim explained that a one part per billion concentration is
approximately one drop mixed in a large tanker truck of water. In other words, a very small
amount in solid waste can contaminate groundwater at levels of health concern. The solvent is
used as an adhesive in PVC pipes since the 1970s and as a solvent in lacquers. The chemical
vaporizes and degrades rapidly in well ventilated areas, but it degrades very little in
groundwater. The state standard is based on the chemical’s potential effect on fetal
Kim said to imagine a citizen who had a mostly used quantity of PVC adhesive in a sealed
steel can that they threw out with their garbage. In a time before can recycling and Clean
Sweep hazardous waste collections, it was a likely choice for disposal. As the organic waste
around the container in the landfill degraded, the garbage became acidic and corroded the
steel until the solvent leaks out with the leachate. No one knows how many cans of solvent
were in garbage placed in the landfill over fifteen years.
When the concentration of a substance in groundwater exceeds a state Preventive Action
Limit at the boundary of a facility, The Department of Natural Resources (DNR) must decide
what, if any, actions are appropriate to prevent such concentrations from exceeding the state
Groundwater Standard. Kim said he asked Nathan Coller, the DNR regional hydrogeologist in
Spooner when a DNR staff member could meet with local officials at the landfill site to
explain what next steps are appropriate. Nate said he would ask Sonny Zentner, a DNR
regional engineer in Eau Claire to set up a visit, but Sonny likely would not be able to visit
until later in the fall or next spring.
Kim explained that, because nobody knows how many or what types of potentially toxic
chemicals may have been mixed with the garbage placed in the landfill, monitoring and
maintaining a closed landfill is a perpetual responsibility. The Washburn Town Board this
year assigned the Town Plan Commission with the task of annually monitoring the landfill
and making recommendations for maintenance of the site. The commission intends to prepare
a checklist of items to monitor and of required maintenance needs to recommend to the Town
Board and partner municipal officials. As officials step down and new ones take over, it will
be important to assure that annual monitoring and maintenance is not forgotten because
increased concentrations of contaminants in groundwater could lead to required repairs
costing several million dollars. The Town of Barksdale currently provides 47 homes with
water piped from the City of Washburn. That clean-up was funded by an industrial polluter,
but the landfill management is a municipal liability.
Wendy pointed out several invasive noxious weeds growing on the landfill site: spotted
knapweed and leafy spurge. She mentioned two steps to reduce the spread of weed seeds from
the property: 1) as much as possible, mowing the site after the plants flower but before they
produce seeds, and 2) minimizing the extent to which vehicles on the property might carry
seeds offsite in tire treads. It may also be appropriate to apply weed control chemicals to
reduce the abundance of weeds.
The group observed several tree stumps
excavated from the realignment of South
Maple Hill Road that were stacked east of
Monitoring Well #3 and a pile of soil from
the project. Several suggested that it would
be appropriate to mark clearly the boundary
between the landfill site (a shared
responsibility of the town, the city, and the
Town of Bayview) and Town of Washburn
property outside of the site. The group asked
to be informed about what follow-up
maintenance is to be done.
3. The meeting adjourned at 4:30 P.M.
Draft submitted by: Kenneth Bro, Chair, Town of Washburn Plan Commission
(November 6, 2022).