The monitoring well to be installed near Well 8 has been postponed. Next year, Madison Water Utility will re-evaluate when to move forward with the $110,000 project. The monitoring well installation was originally scheduled to move forward in 2018 but has been delayed due to budget constraints.
A new monitoring well is not required by the Wisconsin Department of Natural Resources, but it could serve as an early warning should tetrachloroethylene (PCE) travel from the Madison Kipp groundwater contamination area toward Well 8.
Madison Water Utility currently plans to operate Well 8 on a limited basis this summer from the end of July through most of August, depending on weather conditions.
Concerns about Madison Kipp
Well 8 became the focus of neighborhood concern after a chemical called PCE (tetrachloroethylene) was found in groundwater at nearby Madison Kipp Corporation property. In 2013, a shallow monitoring well found very low levels of PCE in the upper aquifer about 600 feet from Well 8. It's important to note that no PCE has ever been found in the water at Well 8. Madison Water Utility routinely tests water pumped from Well 8 when the facility is in service, and no PCE has been detected.
PCE Plume Evaluation Report & Planned "Sentinel" Well
Madison Water Utility plans to drill a small “sentinel well” in hopes of detecting PCE if it moves toward Well 8. The utility hired an independent consultant, hydrogeologist Eric Oelkers with SCS Engineers, to analyze groundwater movement in the Well 8 area and locate an appropriate site for the monitoring well.
The objectives of Oelkers' study were:
- Evaluate the stability of the PCE plume utilizing groundwater data collected since the first consultant completed her report. Determine if the plume is advancing, retreating, or has stabilized.
- Identify gaps (three-dimensional) in the current monitoring. Recommend an additional groundwater monitoring location and screen intervals.
- Refine the existing subsurface conceptual model for the area. Re-evaluate the hydrogeological units and calibration points used by Arcadis in their fracture flow model. Re-run fracture flow model if necessary.
- Work with Wisconsin Geological and Natural History Survey (WGNHS) staff to identify potential effects of various pumping scenarios at Well 8on the local groundwater flow system using the new regional aquifer groundwater model.
- Identify a possible location and vertical coverage for a groundwater “Sentinel Well” system. This system would identify migrating contaminants before they reach Well #8.
Oelkers completed his PCE Plume Evaluation Report in October of 2017 and recommended that a sentinel well be drilled in an area northwest of Well 8 near Lowell Elementary. Madison Water Utility will now work to determine an exact location for the monitoring well, which will be about six inches in diameter. Once the well is drilled, samples will likely be drawn and analyzed quarterly for the first two years to collect background data, then twice a year after that.
Located in Olbrich Park on Madison's east side, Well 8 is 774 feet deep and draws water primarily from the lower aquifer below a natural barrier known as the Eau Claire Shale. The well also has an attached underground reservoir, which forms the basis of the sledding hill at Olbrich Park.
Well 8 was drilled in 1945, and although it was initially operated year-round, it is now used only during the high-demand summer months because it contains naturally occurring iron and manganese, which can cause discoloration. Still, supply provided by Well 8 can be crucial. The well played a critical role in refilling East Side reservoirs during and after the Apollo Way fire in August of 2014. Crews used an estimated 2 million gallons of water to fight the fire.
Looking to the future
Instead of drilling a new well to meet supply needs on the East Side, Madison Water Utility may eventually reinvest in the Well 8 facility in order to use it year-round once again. That would mean rebuilding the aging facility and installing iron and manganese filters, similar to the ones recently installed at Well 7 on the North Side. But it also means further study of the contamination plume near Madison Kipp and its potential to impact the well. PCE can be successfully removed from water, and any rebuild of Well 8 would include provisions to add a future treatment system to remove PCE and other volatile organic compounds if necessary.