Malfunction of the Southeast Infiltration Basin (former Biofilter) and Northeast Infiltration Basin at the Flambeau Mine Site


Photo 1.  Flambeau Mine Southeast Infiltration Basin (former Biofilter) looking north – staff gauge in foreground. The gauge shows a water depth of about 40 inches. The Wisconsin Department of Natural Resources (WDNR) technical standard for an infiltration basin (Tech. Std. 1003) specifies a maximum water depth of 24 inches  (photo by Terry Koehn, WDNR, April 12, 2013).

Between October 2011 and April 2012 Flambeau Mining Company (FMC) constructed three infiltration basins  at the Flambeau Mine site to handle contaminated runoff from the partially reclaimed mine operation. To read about the events leading up to the construction of the basins, click here.

At least two of the three basins (which were designed by Foth Infrastructure & Environment of Green Bay, WI) did not function as planned.  As described in a December 2012 memo from the Wisconsin Department of Natural Resources (WDNR) to Flambeau Mining Company:

“… we understand that the project remains under construction. However, the infiltration basins did not function as planned in 2012. The basins maintained a more or less permanent pool of water unless mechanically pumped out. You should be aware that ponds within 500 feet of public waters such as Stream C or the Flambeau River require a permit under Chapter 30 WI State Stats. If the basins cannot be constructed to meet infiltration basin standards and continue to maintain a pool of water you will need to obtain a Chapter 30 permit to maintain those basins within 500 feet of public waters.”

A critical situation involving the malfunction of the southeast (former Biofilter) and northeast infiltration basins occurred in April 2013 with the spring melt. A string of emails between WDNR and Foth/FMC obtained through an open records request reveals that: (1) the two basins came within 6 to 12 inches of overflowing their berms in April 2013; and (2) a similar situation had taken place in the spring of 2012. You can read the panicked account of what transpired between WDNR and Foth/FMC officials by clicking here.

The email string cited above is significant in that Foth’s James Hutchison had testified during a May 2012 federal court trial in which violations of the Clean Water Act were alleged and proven against FMC, that the infiltration basins were designed to withstand a 100-year flood event. Yet, the basins had nearly overtopped either shortly before or shortly after Hutchison rendered his testimony in 2012 (the exact date of the incident is unclear) … and due to circumstances not nearly so taxing. In addition, the repeat episode of a near overflow of the basins in 2013 confirmed the flawed design of the basins.

As an aside, Huthchison is the same Foth official who, under oath at the Clean Water Act trial, testified that the “blue line” clearly shown on several Foth diagrams depicting the flow of water from the biofilter to Stream C,  did not correctly portray the hydrology at the mine site. Rather, Hutchison claimed that the “blue line,” which he took responsibility for drawing on those diagrams, was just something “in [his] head.” This was part of FMC’s overall  strategy, at trial, to assert that contaminated water from the biofilter had never made its way to Stream C and that the company, therefore, was not in violation of the Clean Water Act. Luckily the judge didn’t buy it.

Back to the infiltration basins … WDNR hydrogeologist Terry Koehn visited the Flambeau Mine site in November 2012 to observe work done by Foth/FMC in efforts to improve the performance of the infiltration basins. You can read Koehn’s memo and see a number of photos he took by clicking here. Unfortunately, the work done by FMC did not fix the problem, as evidenced by the near overflow of the basins in April 2013.

On April 12, 2013 Koehn returned to the Flambeau Mine site to observe the condition/water levels in the infiltration basins after FMC had initiated pumping to avoid an overflow situation. Koehn drafted a memo in which he documented the near-overflow status of the southeast (former Biofilter) and northeast basins and submitted five photos with descriptive captions, including two of the southeast basin shown above and below:


Photo 2. Flambeau Mine Southeast Infiltration Basin (former Biofilter) looking east – view indicates limited freeboard. FMC constructed the basin about 4 feet shallower than what had been approved by WDNR in 2011. Still, part of the basin has come within 3 feet of the water table, based on the July 2011 groundwater level. WDNR standards call for a minimum separation of 5 feet (photo by Terry Koehn, WDNR, April 12, 2013).

So how could this near overflow of the infiltration basins have happened? Internal correspondence between WDNR officials reveals that Foth/FMC altered the construction plans for the southeast (former Biofilter) and northeast infiltration basins after the original work plan had been reviewed and approved by WDNR. As a result of the changes implemented by Foth/FMC, the basins, as constructed: (1) do not meet WDNR technical standards for infiltration basins; and (2) are too shallow and too close to the groundwater table to effectively handle contaminated runoff from the mine site. You can read the details for yourself and examine comparative diagrams of the “As Approved” vs. “As Built” southeast (former Biofilter) infiltration basin by clicking here.

As described in the WDNR correspondence cited above, Foth apparently used outdated (2009) data when doing its hydraulic computer modeling for the infiltration basins. The groundwater table encountered during construction (2011-2012) was higher than anticipated, “with an increasing slope toward Stream C.” Foth proceeded to alter the infiltration basin work plan and constructed the basins about four feet shallower than what had been approved by WDNR. This puts part of the southeast basin within 3 feet of the water table, based on the July 2011 groundwater level, while WDNR standards call for a minimum separation of 5 feet.  It appears the company did not seek or obtain official approval from WDNR before altering the infiltration basin construction plan, even though the plan had been the subject of a public hearing and stringent department review in August 2011.

The following is what WDNR Water Resources Engineer Bruce Moore wrote in an internal WDNR memo dated April 2, 2013. His remarks are included here in their entirety because of how they were “right on the money,” as proven one week later when the southeast and northeast infiltration basins at the Flambeau Mine site almost overflowed:

“DNR recently received the As-built drawings for the Flambeau Mining Company infiltration basins.  Per previous discussions, the basin bottoms were set at a higher elevation than initially planned, in response to higher groundwater table levels measured in 2011 (The 2009 gw measurements were taken during a multi-year drought.).   Top of berm was not also revised to reflect the shallower bottom, however, thereby reducing the basins’ stormwater retention capacity.

I have not received a copy of the As-built drawings for my review, and would request a copy for the stormwater program files.  Jon needs his copy to support the Chap. 30 program.   In the interim, I can make the following general remarks:

1.Previously, the landowner had the intention of retaining site runoff up to the 100-yr storm event.   I believe this was driven primarily by the recognition that the water quality standard for copper in groundwater is more forgiving than that for surface water flows to water bodies.  In addition, the process of water moving through soils can provide a beneficial filtering or in-situ treatment aspect.   As a result, the more site runoff that could be infiltrated, and surface discharges minimized, the better for local water quality.

Whether the basins can still retain the 100-year event is now in question.  The hydraulic model should be run again to ascertain the basins’ actual holding capacity (in terms of storm event frequency), based on the as-built berm elevations and 2011 groundwater table level.

2. DNR’s technical standard for an infiltration basin (Tech. Std. 1003) specifies a maximum water depth of 24 inches.  It is likely that the water depth in the infiltration basins serving the Flambeau mining site will exceed this maximum depth.  Here as well, emphasis was placed on maintaining a minimum 5 feet vertical separation between the basin bottom and groundwater table level.  The second (i.e., Downgradient ) basin is constrained on three sides by existing buildings, the entry drive to those buildings, and wetlands.

3.  On the presumption that some increase in basin berm height will be necessary on the heels of obtaining the As-built modeling results, consideration should be given to providing the downgradient basin with a bona fide emergency overflow structure that can accommodate a 100 -year storm event.  Barring intermittent pumping, this is the most direct way of minimizing the possibility of catastrophic failure of one or more berm walls in the event of a very large and intense rainfall event.

4.  A landowner is not required to design BMPs to satisfy its associated DNR technical standard.  However, if he chooses to deviate from the elements of a technical standard, it is incumbent on the landowner to provide compelling evidence to DNR that the design will adequately protect water quality.

5.  Given the negative implications of surface discharges on the aquatic community, any future design should continue to emphasize infiltrating as much surface runoff from the site as possible.”


Bruce A. Moore, P.E., Water resources engineer / Hydrologist

Wisconsin Department of Natural Resources – Northern Region, 2501 Golf Course Rd., Ashland, WI 54806; phone: (715) 685-2926;  fax: (715) 685-2909;  e-mail:

Moore’s memo was written in response to an email from WDNR’s Jon Kleist that provides additional information about the flawed design of the infiltration basins at the Flambeau Mine site, including comparative diagrams of the “As Approved” vs. “As Built” southeast (former Biofilter) infiltration basin.

2014 Update:  Infiltration Basins Continued to Malfunction

As of late 2014, the problems with FMC’s infiltration basins still were not fixed. As noted in an October  31, 2014 email from WDNR’s Phil Fauble to Laura Gauger:

“In brief, we have been monitoring the situation with the basins and have noted that the basins were nearly filled to capacity during the Spring 2013/14 melts and exceptionally large rainfall events. When that happens, FMC is required to activate pumps to lower the water level in the basins. We have shared our concerns with FMC that periodic pumping is not a long-term solution to the problem. It is our understanding that FMC is working on a solution and will be submitting something for our review in the near future.”

Laura Gauger responded to the above information as follows in a November 3, 2014 email sent to Mr. Fauble:

Thank you for the information you provided. [Considering that the infiltration basins malfunctioned in 2012 as well, they have now] … malfunctioned for the past 3 years. How much longer is WDNR willing to wait before taking some sort of enforcement action against FMC (e.g., requiring a Chapter 30 permit, as suggested by Jon Kleist in his Dec 2012 memo to FMC)?

It seems that whenever a citizen like me is subject to a WDNR timeline (e.g., submitting comments on various proposals), the timeline is strictly enforced by the department. Yet, here we have an acknowledged problem with how FMC is handling polluted runoff at the Flambeau Mine site, and there appears to be no timeline/deadline for fixing it.

Another frustrating aspect to all this is that FMC trotted out their infiltration basin plan during our recent Clean Water Act case against them in federal court, implying they had fixed any and all problems we had raised in our complaint. The court “bought it,” and , as you know, ultimately required us to reimburse the company $61,500 in court costs (my share $20,500) – quite a heavy burden for me. Now, the company’s “fix” has proven inadequate and there appears to be no recourse.

Could you please get back to me on this? Again, what I would like to know is this: How much longer is WDNR willing to wait before taking some sort of enforcement action against FMC (e.g., requiring a Chapter 30 permit, as suggested by Jon Kleist in his Dec 2012 memo to FMC)?

As of December 31, 2014, WDNR had not responded to Gauger’s question.

Water Quality Monitoring for the Flambeau Mine Infiltration Basins

The installation of the infiltration basins at the Flambeau Mine site took place between October 2011 and April 2012, and a monitoring plan to assess the performance of the basins supposedly is in effect. Still, as of May 2013, FMC had not provided WDNR with any surface water quality data from the infiltration basins or any new data for the Stream C sampling sites identified in the infiltration basin monitoring plan.

As of a May 28, 2013 open records request, the only recent data on record at WDNR for Stream C was for just two water samples collected from the stream in June 2012 (see map for site locations). Copper values in those samples significantly exceeded water quality standards set to protect fish and other aquatic species:

    1. SW-C1: Copper = 63        (Chronic Water Quality Standard for Copper =  4 to 5, based on water hardness measured at sampling location)
    2. SW-C3: Copper = 9.1       (Chronic Water Quality Standard for Copper = 2 to 3, based on water hardness measured at sampling location)

Why such limited data? Per the terms of FMC’s Chapter 30 permit (required for construction of the infiltration basins), the company was supposed to devise and implement a monitoring plan for the infiltration basins by March 2012. But, as mentioned in a December 17, 2012 memo  from WDNR to FMC, it is clear that the company fell far short of meeting the deadline. Indeed, FMC did not submit a final draft of its infiltration basin monitoring plan to WDNR until February 2013 (almost a year late).  The draft included a diagram showing the monitoring sites for Stream C and the infiltration basins and specified that samples were to be collected 4 times a year for 3 years. In March 2013 WDNR approved the plan, with the following correction:

“We agree with the sampling locations, parameters, frequency and reporting as presented in the plan. We have only one minor correction, which is to state that, “A qualifying storm water runoff event will be determined by having visible surface water flow from the culvert under Highway 27 at SW-C9 and in the channel of Intermittent Stream C at SW-C1 which will trigger the sampling.” . The purpose of this requirement is to make sure FMC is not sampling stagnant surface water which could lead to water quality results that are not representative of the true water quality in Stream C.”

In May of 2013, attorneys for the Wisconsin Resources Protection Council and Laura Gauger did an open records request of the Wisconsin Department of Natural Resources to obtain, among other things, any monitoring data submitted by FMC to the department subsequent to implementation of the infiltration basin monitoring plan. A response was received on May 28, 2013, and, as of that date, FMC had not submitted any surface water data to the department.

On July 24, 2013 FMC finally reported its first round of surface water data for the infiltration basin monitoring plan, and the second round was reported in January 2014. Instead of going down, copper levels in Stream C have actually gone up and are indeed higher than ever reported before (81 mcg/l at sampling site SW-C1 in October 2013). Indeed, the company’s “fix” for trying to decrease the toxic levels of copper in Stream C has proven ineffective. Indeed, it appears that FMC has made the problem worse. You can read for yourself:

To see graphs of historic and current copper levels measured in Stream C, immediately downstream of the Flambeau Mine site (sampling site SW-C1), please click on the below links:

For more information regarding the infiltration basins at the Flambeau Mine site, click HERE.

For historic Stream C water quality data (1999-2014) click HERE.

For new developments (2015 and beyond) regarding the infiltration basins at the Flambeau Mine site, please go to my supplemental website, Flambeau Mine Exposed-II.