northmet comments by daniel pauly

NorthMet SDEIS Comment Daniel Pauly Page 1

Comments Overview:

On the following pages I have outlined issues identified with regard to the NorthMet Project proposed

by PolyMet Mining, Inc. These comments address following general topics:

1) The SDEIS assessment of Tailings Basin mercury contamination conditions is fraught with

systematic data integrity problems that include mathematical errors in key formulas, improper

selection of data sets, and suspected sample collection errors.

2) The errors and omissions in the Tailings Basin dataset have permeated the SDEIS and its

supporting reports, resulting in incorrect fundamental conclusions as to current and future

mercury discharges at the Tailings Basin and Waste Water Treatment Plant. In particular, the

Tailings Basin and Waste Water Treatment Plant as proposed are likely to significantly increase

total mercury, and especially methylmercury, loading in the Embarrass River watershed.

3) In view of the data integrity issues and improper mercury discharge conclusions, the NorthMet

SDEIS should review previously discarded Tailings Basin alternatives.

A summary of these comments is provided on the following pages, with detailed individual comments

following thereafter.

Comments Summary:

SECTION 1: Errors & Omissions in Tailings Basin Mercury Data and Analysis

The NorthMet SDEIS assessment of current and future Tailings Basin mercury seepage is fraught with

problems. These problems include mathematical errors in key calculations, improper selection of data

sets, exclusion of probative conflicting information, and suspected sample collection/analysis errors.

These flaws have resulted in SDEIS drafters reaching the erroneous conclusion that Tailings Basin

mercury seepage will meet Great Lakes Initiative standards of 1.3 ng/L.

Of particular note are errors in the calculation for average water quality at the Tailings Basin. As

described in detail in my comments, the preparers of the SDEIS failed to appreciate that some of their

data was in the units ng/L, and some of it was in the units ug/L (a ug/L is 1000 times greater than a

ng/L). This failure resulted in large errors in a key SDEIS summary of mercury contamination, which

incorrectly states that the majority of water seepage sites were below the Great Lakes initiative mercury

level, when in fact most of these sites were actually above the Great Lakes Initiative level.

These errors and others are discussed on the following pages, and have been magnified by overreliance

on improper subsets of data. Specifically, the SDEIS repeatedly considered only data that would show

favorable mercury levels, while ignoring data to the contrary. Specific instances included the following:


1. The Tailings Basin has four active NPDES monitoring locations that are positioned to

intercept Tailings Basin seepage. NorthMet documents state that these monitoring

locations provide the best data for determining Tailings Basin discharges. Inexplicably,

the SDEIS relies almost exclusively only on data from one of these discharge locations

the one that appears to show seepage below 1.3 ng/L. All three of the other discharge

locations, including one that is better positioned relative to the likely flow of NorthMet

discharges, were essentially ignored. The result is an improperly skewed assessment

that mercury levels will be lower than 1.3 ng/L. Correction of this error shows mercury

discharges above 1.3 ng/L.

2. Looking beyond NPDES monitoring sites, a comprehensive review of mercury seepage

data collected over time at the Tailings Basin also shows that Tailings Basin seepage will

exceed Great Lakes Initiative mercury levels of 1.3 ng/L. Despite the availability of this

information, it is essentially ignored in the SDEIS.

3. The SDEIS also relies upon a faulty mercury sequestration test that predicts remarkably

low mercury levels in Tailings Basin seepage, while ignoring a superior test that does not

predict significant sequestration. Specifically, the SDEIS gives great weight to a very

flawed 8 hour experiment with NorthMet tailings in a flask, while never even

mentioning in the SDEIS a much more comprehensive test prepared for the NorthMet

site that showed mercury levels are likely to be significantly above Great Lakes Initiative

standards.

4. The SDEIS includes an Assessment of Existing Pond Water and Groundwater Quality at

the Tailings Basin that shows mercury seepage at nearly six times the Great Lakes

standard for mercury discharges. This result is inexplicably not discussed further in the

SDEIS.

SECTION 2: Mercury assessment errors lead to faulty WWTP design and pilot testing, as well as a

defective containment system, both of which will likely lead to significant

methylmercury discharges into the Embarrass River watershed

A combination of errors and faulty analysis cause the SDEIS to erroneously conclude that Tailings Basin

mercury discharges will be below 1.3 ng/L. These errors result in numerous misstatements and faulty

conclusions in the SDEIS. Two of these deficiencies lead to notable flaws: 1) failure to design and test a

Waste Water Treatment Plant (WWTP) that will adequately determine viability of mercury removal; and

2) design of a discharge capture system that incorporates a wetland that will receive the majority of the

mercury and sulfate from the Tailings Basin, and which will meaningful increase mercury contamination

in the Embarrass River watershed.

One of the most critical long-term components of the entire NorthMet project is the performance of the

Tailings Basin, and the most critical component of Tailings Basin performance is the ability of the WWTP

to remove toxins and contaminants. The operation of this plant represents the biggest long term post-

closure expense at the NorthMet site, and will likely run for at least hundreds of years. It is essential


that decision makers have a reasonable basis for concluding that mercury can be removed by the

proposed WWTP, as well as the long term costs for such removal.

The WWTP will use reverse osmosis to remove contamination from Tailings Basin seepage. The SDEIS

discusses a pilot test for the WWTP that was conducted in 2012. Unfortunately, the WWTP pilot test

never evaluated mercury removal using reverse osmosis. In fact, as the Pilot Test report itself states,

the WWTP designers dont know how much mercury can be removed by the WWTP. The report states

that maybe as little as 20 percent, or maybe as much as 99 percent, of mercury might be removed. One

guestimate is given by a salesperson for PolyMets membrane manufacturer of about 70 percent for

mercury removal. Even then, according to the SDEIS documents, removal of methylmercury does not

appear possible using the planned WWTP design. In other words, removal of the most hazardous

species of mercury, the one that bio accumulates in fish and humans, has not even been considered in

the WWTP design.

The challenge now is that the NorthMet site has an inadequate mercury assessment that lead to an

improperly designed pilot test, which results in tremendous uncertainty about whether PolyMet will be

able to adequately remove mercury from Tailings Basin seepage and WWTP inflows. Even more

uncertain is what that cost of implementing an adequate removal system is likely to be.

The SDEIS seeks to address these concerns with a proposed adaptive engineering approach for the

WWTP design and operation. An adaptive engineering approach is inconsistent with best practices in

the literature for removal of contaminants using reverse osmosis, because each location and system has

unique problems and challenges. Due to the relatively complex design of the NorthMet project water

flows, including significant seasonal variations of likely methylmercury flows, the WWTP will need to

remove disparate contaminants from quite variable influent streams. By approaching critical issues and

long term challenges with an adaptive engineering approach, the NorthMet project risks decades of

uncertainty, contaminant release violations, and unforeseen costs because the analysis will be

undertaken long after the mine is in operation, and some of analysis wont be undertaken until after the

mine is closed. This approach fails to provide decision makers with adequate information to assess what

the treatment costs will be. For example, it is possible that mercury removal alone could add significant

costs to WWTP as currently envisioned, because the various species of mercury are removed by

different types of technology. Inexplicably, the WWTP and Pilot Test never even consider mercury

removal as an issue, and so no site-specific costs for mercury removal can be calculated.

The second problem that has been overlooked relates to changes in the NorthMet proposed Tailings

Basin since the DEIS was prepared. Specifically, the currently proposed NorthMet Tailings Basin has

been modified since the DEIS to create a containment system outside of the Tailings Basin. The

containment system will include an up to 160 acre wetland that will be receiving the mercury and

sulfate laden waters from the combined LTV/NorthMet tailings. These seepage flows will increase

relative to the current LTV tailings basin, and create a much larger wetland than currently exists. The

NorthMet projects own model data shows in great detail that most mercury and sulfate will be

delivered directly to this wetland, and not to the containment system drains.


Contemporary research, including important research recently conducted in Minnesota, shows that this

wetland, with its mixture of mercury, sulfate, and organic matter, is a prime environment for

methylation of mercury. In fact, recent research by government investigators in Minnesota in the last

few years has shown shockingly high levels of methylmercury in wetlands, including methylmercury

spikes at the toe of taconite tailing basins. The SDEIS never asks what will happen to that

methylmercury. It is likely that some of it is going to be carried to the WWTP, but as the WWTP pilot

test itself reports, there is no plan for removing it. What happens to the rest of the methylmercury,

which might be the majority? Current research shows it will be absorbed by everything from mosquitos

to earthworms, and will then travel up the food chain throughout the Embarrass River watershed.

SECTION 3 Tailing Basin Alternatives were Prematurely and Improperly Eliminated

As detailed in the attached comments, the present plan for the NorthMet Tailings Basin is to reuse LTVs

60 year old unlined tailings basin that contains decades of heavy mercury loadings. The existing LTV

tailings basin has been drying out since 2001, and seepage volumes have declined. As noted in the

SDEIS with reference to the No Action Alternative, the LTV tailings basin should continue to dry out in

coming years, with a concurrent drop in contaminated discharges.

The NorthMet recommended action is to essentially build another unlined Tailings Basin on top of the

current unlined and inactive tailing basin, but this time with tailings that are likely to be higher in

sulfates than the existing mercury-rich tailings. Water from the new Tailings Basin will seep through the

old taconite tailings, and then be discharged out the bottom into a large wetland area. In the wetland

mercury methylation is likely to occur, and the methylmercury will bio-accumulate in the wetland life

forms, before being carried out into the Embarrass River watershed by everything from bugs to birds.

Some of the mercury, whether methylated or not, will travel to the NorthMet proposal Waste Water

Treatment Plant. However, the SDEIS has no plan to remove that mercury, and the SDEIS documents

indicate removal may not even be possible with the reverse osmosis technology planned for the waste

water treatment plant.

In view of the information available, two alternatives, at a minimum, should have been considered more

thoroughly to see if they could have avoided the problems of perching a new unlined basin on top of an

old unlined basin: either (a) putting a liner between the basins; or (b) locating the new basin

somewhere other than on top of an old unlined basin. Both of these alternatives offer significant

improvements in regards to preventing release of mercury from the existing LTV tailings basin, avoid the

interaction of seepage water between two different types of tailings, and allow for what will likely be a

significantly less complex and less expensive waste water treatment facility. These two proposals would

require a much more significant up-front capital cost, but would reduce long term costs and

accompanying uncertainty. To the extent long term costs are an issue to project approval, consideration

of these options should be undertaken to remove that uncertainty. Overall, it seems quite possible that

either of these two options could offer the mutual benefit of lower costs and improved environmental

protection.


These two alternatives were dismissed very early in the EIS process. From my review of the DEIS and

SDEIS, I believe these alternatives were prematurely dismissed because DEIS and SDEIS preparers

overlooked the fact that that mercury contamination would be an issue. The thorough review of these

(and other) alternatives is obviously beyond the scope of these comments. However, at the end of

these comments I provide a simplified matrix showing how these two alternatives compare in

effectiveness and cost relative to the proposals in the SDEIS.

Further note that viable implementation of either of these options is really only available now, before

the NorthMet project proceeds, because neither can be retrofitted onto the project once it has gone

forward. In other words, it will be too late in 10 or 20 years, once the Tailings Basin has been filled, to

find out that there might have been a better and cheaper way. Should the adaptive engineering

approach to the WWTP prove unworkable for long term water treatment, it will be too late, or at least

unfathomably expensive, to segregate the NorthMet tailings and LTV tailings.

Conclusion

In conclusion, the errors and omissions in mercury analysis has led to subsequent failures to address the

capture and removal of mercury before it can escape into local and regional waters. The long term

economically-viable removal of mercury has not been assessed, but should be. In addition, prematurely

dismissed alternatives should be evaluated before proceeding further with the NorthMet project.

Failure to adequately assess the likely level of mercury contamination, and the expense to prevent it,

will potentially result in long term damage to the St. Louis River watershed and enormous unforeseen

future costs.


PAULY COMMENT SECTION 1

The NorthMet SDEIS assessment of Tailings Basin mercury contamination is fraught with systematic problems that include mathematical errors in key calculations, improper selection of data sets, exclusion of probative conflicting information, and suspected sample collection or analysis errors. These shortcomings have resulted in reaching the erroneous conclusion that Tailings Basin seepage will meet Great Lakes Initiative standards of 1.3 ng/L.

1. The SDEIS contains major computational errors in mercury seepage from the Tailings Basin.

Mercury is one of the most significant potential water contaminants from the NorthMet Project.

Contamination of local surface and groundwater from the Tailings Basin is of particular concern.

As noted in the SDEIS, the proposed NorthMet Tailings Basin will have significant levels of water

seepage indefinitely, and the volume of discharge water will be increasing significantly

compared to current conditions. The level of mercury in that seepage water is critical to

evaluating the environmental impacts of the NorthMet project, as well as the financial viability

of seeking to remove the mercury.

Table 4.2.2-4 of the SDEIS, reproduced in relevant portion below, provides a summary of total

mercury in the Embarrass River watershed near the Tailings Basin. In particular, Table 4.2.2-4

provides mean mercury levels for water seepage at 11 locations at the Tailings Basin. The

accuracy of these numbers is paramount to understanding the potential for mercury

contamination from the Tailings Basin.

According to Table 4.2.2-4, many of the most heavily sampled locations in the Tailings Basin

have mercury levels are significantly below the Great Lakes Initiative. In fact, Table 4.2.2-4

shows five locations, highlighted in yellow for this comment, which have mercury levels below

1.0 ng/L.

Table 4.2.2-4 was prepared using information in SDEIS appendix Barr 2006f, which I received

from Ms. Lisa Fay of the Minnesota Department of Natural Resources. Barr 2006f allows for

reconstruction of the mercury contamination calculations for each of these sample locations.

In reviewing the data in Barr 2006f, I identified a fundamental mistake in the summary results:

The calculations had a major error because the sample data was presented in two units:

nanograms per liter (ng/L) and micrograms per liter (ug/l), yet the calculations ignored these

different units. Reproduced below is a portion of page 113 of Barr 2006f, showing the table

heading for columns of mercury discharge data for Cell 1E:


Data in the left hand column is presented in ng/L, while data in the right hand column is

presented as ug/L. For reference, the data on the right can be expressed as


Pauly Comment Figure 1 Excerpt from Barr 2006F

Consistent with Table 4.2.2-4, this excerpt for Cell 1E shows 25 different sample results. In the

left column three of the samples had mercury levels between 0.9 and 1 ng/L. In the right hand

column the other 22 samples are shown. These right-hand samples are all assigned the value of


was 200 ng/L.1 The individual who calculated the data for SDEIS Table 4.2.2-4, and all the

subsequent proofers and reviewers, never noticed that the units on Barr 2006f are not

consistent from one column to the next. They incorrectly concluded that all of these data points

are in the same units.

Specifically, with regard to Cell 1E, Table 4.2.2-4 reports total mercury at the Cell 1E location is

0.2 ng/L. This number appears to have been reached by considering all of the numbers in the

Barr 2006F report to be in ng/L, including those that are in ug/L. The preparer of the SDEIS

table used half of each minimum detection limit (see footnote 4 to Table 4.2.2-4 of the SDEIS),

but erroneously assumed the units should be nanograms. The preparer then averaged the

readings with the three readings from the left column. In other words, it appears the preparer

assumed that all the readings of


The Emergency Basin mercury concentration calculations also have errors similar to Cell 1E. The

correct level, based upon the available data, is probably closer to 1.8 ng/L, which again is nearly

40 percent over the Great Lakes Initiative level.

The West Seep mercury concentration calculations also has errors similar to Cell 1E, and

understates mercury concentration by a similarly large magnitude.

1.1 Another error in Table 4.2.2-4 is that most samples were improperly reported as non-detects for mercury.

Not only is the mean total mercury concentration incorrect in Table 4.2.2-4, but it is important

to note that SDEIS Table 4.2.2-4 also dramatically overestimates the number of non-detect

samples for mercury. The error is that the minimum detection levels were far above the actual

Great Lakes Initiative levels, so a non-detect in many cases means only that the mercury levels

were below the very high 200 ng/L, rather than a modern detection level of 0.5 ng/L. Non-

detects for such high minimum detection levels should not be considered to be non-detects

when the regulated target level for mercury is 1.3 ng/L.

The problem is that someone reviewing Table 4.2.2-4 would mistakenly conclude that the

number of samples with detectable levels of mercury was very, very low. This presentation of

the data is profoundly misleading, because in fact almost all of those non-detects came from

analysis that had very high minimum detection levels. A person reviewing Table 4.2.2-4 is likely

to be misinformed about the data, and reach the erroneous conclusion that almost all of the

samples at the ten sample locations were below a modern detection level of 0.5 ng/L.

1.2 Correcting these errors in the SDEIS mercury discharge calculations leads to a radically different view of likely NorthMet Tailings Basin mercury discharges

Once Table 4.2.2-4 is updated to correct these calculation errors, a radically different

assessment of likely mercury discharges from the NorthMet project becomes evident. Rather

than being below the Great Lakes Initiative standard of 1.3 ng/L, at 6 out of 11 seepage sites,

probably 10 out of 11 seepage sites are above the Great Lakes Initiative standard. In the

following pages I provide additional analysis that confirms this conclusion and make

recommendations as to how to address these higher than assumed mercury discharge levels.


2. The NorthMet Tailings Basin assessment improperly underestimates mercury discharges by disregarding data from three out of four of the NPDES monitored surface discharge locations at the Tailings Basin.

In addition to the erroneous calculation with regard to water quality at numerous Tailings Basin

locations, the SDEIS has improperly selected a subset of NPDES water sampling locations that

has also resulted in a meaningfully inaccurate assessment of current conditions at the Tailings

Basin.

The Tailings Basin has four active seeps that have been monitored since the closing of the LTV

plant site. In the PolyMet water quality analysis, which is an appendix to the SDEIS, PolyMets

water quality scientists state that NPDES surface discharges from the Tailings Basin serve as the

best proxy for concentrations of mercury seepage from the existing Tailings Basin. PolyMet

2013j at page 271. SD006 is in the southeast corner of the Tailings Basin, SD001, SD004, and

SD005 are in the northwest corner of the Tailings Basin; and SD002 is in the north central

portion of the Tailings Basin. There was apparently never an SD003, so there is no data. Also,

SD005 has essentially been dry and not sampled for most of the last 13 years.

That leaves four NPDES sample locations to review: SD001, SD002, SD004, and SD006 consistent

with the opinion of PolyMets water model that these discharges are the best proxy for

concentrations of mercury seepage from the existing Tailings Basin. Despite the fact that this

seepage data is so critical to assessing mercury contamination, only Tailing Basin data from

SD004 is used to support the determination that mercury levels will be below Great Lakes levels.

SD0026, which is at the plant site and not the Tailings Basin, is also used, but it gives no

indication of likely Tailings Basin discharges. In fact, it is not located in the Embarrass River

watershed like the Tailings Basin.

In order to evaluate whether this single sampling point should be the primary empirical

assessment of groundwater conditions, I obtained NPDES sampling data from the Minnesota

Pollution Control Agency for all four of the Tailings Basin NPDES surface discharges. I then

evaluated total mercury in the Tailings Basin for each of these sample locations, but with more

up to date information through 2006 to be consistent with most SDEIS data sets. Based upon

this MPCA data, I calculated total mercury levels for each of the four NPDES locations, plus

average of all samples regardless of which location was sampled (basically a weighted average),

and further an average of the four sites (basically a weighted average). My spreadsheets with

calculations are available upon request, but should be easily reproducible without them because

the data is readily available from the MPCA.

My results are provided graphically below, and are also summarized in the accompanying table.

The graph indicates that rather than SD004 being a representative sample of conditions at the

NorthMet Tailings basin, SD004 is an outlier the one location that isnt above the Great Lakes

standard of 1.3 ng/L. All three of the other locations were above Great Lakes standards, as were

averages weighted by sample number and location.


The following table1 shows a summary of the data used for the calculations:

Location Data Used

Mean Mercury

Level Ng/L2

Included in primary SDEIS data sets for

Mercury contamination?

SD001 2001-2006 1.8 No

SD002 2001-2006 1.4 No

SD0043 2001-2006 1.2 Yes

SD006 2001-2006 1.6 No

In view of the importance of this NPDES data on assessing mercury contamination, it is critical to

look at this data as thoroughly as possible. The selection of only one of four sample locations is

not appropriate, especially when the selected sample location is the only one that shows

mercury levels below the target level, while the other three sample locations are above the

target level.

Recommendation: The mercury modelling for the Tailings Basin mercury data should be

recalculated to include data from all four surface discharge locations at the Tailings Basin site.


1 All data is available from the MPCA website, or can be received from comment author upon request.

2 Mercury levels were calculated consistent with SDEIS protocols. Namely, any test for which minimum detection

levels were above the Great Lakes standard of 1.3 ng/L were removed. Any test for which a non-detect was identified were calculated as 50 percent of the minimum detection level if the minimum detection level was less than 1.3 ng/L. This approach concurs with the methodologies used in the SDEIS tables. 3 SD003 does not appear to exist according to available records.


3. A comprehensive review of Tailings Basin surface discharges confirms that mercury discharges are likely to be above Great Lakes standards, and also confirms that SD004 is not a representative of Tailings Basin seepage.

Comment 2 explained how review of data from all four NPDES monitoring locations at the

Tailings Basin indicates that seepage from the Tailings Basin is above Great Lakes Initiative

standards.

Other data is also available in the SDEIS to allow for an analysis of mercury at the Tailings Basin.

This comment looks at whether a review of additional available surface water data will provide a

different result.

In particular, PolyMets own reports prepared for the original DEIS provide additional

characterization of mercury at the Tailings Basin site. These locations, detailed below, were

sampled for water quality, including mercury. Locations with discharges below Great Lakes

Initiative mercury levels are shown in green. Locations with discharges above Great Lakes

Initiative mercury levels are shown in red.

As can be seen in in this graph and the table below, seven out of eight of the sites/averages for

NorthMet Tailings Basin seepage exceeded the Great Lakes mercury standard of 1.3 ng/L.


Comprehensive Tailings Basin Water Sampling Date

Sample Source

Sample Date

Mean Mercury

Level (ng/L)

Tailings Basin Operation Conditions

Included in the SDEIS assessment

of mercury levels?

LTV-DNR4 1997 2.445 Operation No

PM-86 2004, 20067 2.4 Closure No

PM-9 2004, 20068 3.1 Closure No

PM-10 2004, 20069 2.4 Closure No

PM-11 2004, 200610 3.4 Closure. Note, this location is actually quite far from the site. See Figure 4.2.2-15 of the SDEIS

No

SD00411 2005-08 1.2 Closure Yes

Composite 1997- 2008 2.5

No matter how the samples are interpreted, it is clear that the SDEIS has a profound

shortcoming in relying almost exclusively on data from SD004 as a supposedly representative

sampling location. SD004 is not representative of water discharges at the Tailings Basin, but

rather is an anomaly. The unfortunate decision by SDEIS preparers to select SD004 as

foundation of the Tailings Basin mercury analysis results in flawed arguments, erroneous

conclusions, and unexamined Project alternatives.

4 In researching the literature, the only known measurement of actual seep water mercury levels from the LTV

Tailings Basin is from Berndt et. al 2003, which reported a 1997 test showing 2.44 ng/L of at least one sample. This measure is a potentially significant, because most pre-2001 total mercury tests appear to have been made with higher minimum detection levels, and are thus of no value to characterizing the Tailings Basin during operation. 5 Note that at the time of the LTV measurements in 1997, the Basin mercury levels were 3.48 ng/L, and the seep

was 2.44 ng/L. These relative differences indicate that the tailings may lower the mercury level, but perhaps to an equilibrium level about twice the Great Lakes Initiative. 6 Note that PM-7, PM-8, PM-9 and PM-10 are all identified in PolyMets 2007 Summary and Interpretation of

Surface Water Quality Monitoring Data, PolyMet Mining Company NPDES monitoring locations. Barr (2007i), at page 7. Based upon Figure 1 of that report, which provided a map of all monitoring stations, it appears that PM8, PM9, and PM10 correspond to NPDES sites SD0001, SD002, and SD006. To avoid potential double-counting of the same site in this single table, I am not including SD001, SD002, or SD006 in this table. 7Barr 2006i, table B3

8Barr 2006i, Table B3



11 For cross-reference purposes, SD004 appears to correspond to Seep 22 of various NorthMet reports, including

Figure 4.2.2-11 of the SDEIS.


4. Different conclusions on mercury concentrations at SD004 in the DEIS and SDEIS reveal the problem of over reliance on a narrow subset of discharge data:

The over-reliance on just a small set of data points, especially from just one or two locations at

the Tailings Basin, is problematic because a change in just a couple of samples can completely

change the results, and lead to completely different actions.

A good example of this statistical phenomena can be demonstrated by looking at how NPDES

surface discharge SD004 lead to completely different conclusions between the DEIS and the

SDEIS. Reproduced below are Table 4.1.31 from the original DEIS, and Table 4.2.2-4 from the

SDEIS. These two tables show the same datasets for 11 sample locations at the Tailings Basin.

Note that almost every location has very similar results between the DEIS and SDEIS (with the

exception of some errors in the SDEIS, mentioned earlier).

The one exception to this consistency is SD004, where the mean has gone from 1.9 ng/L from 15

samples in the DEIS, to a mean of 1.2 from 14 samples in the SDEIS. I highlighted in red the DEIS

data for SD004, which is above the Great Lakes Initiative level; and highlighted in green the

SDEIS data for SD004, which is below the Great Lakes Initiative level.


How can the averages be so radically different? It appears, from the limited data I was able to

independently obtain from the Minnesota Pollution Control Agency, that one or two of the

samples in the DEIS was considered to be erroneous, and corrected in the SDEIS.

Im not in a position to say whether the DEIS data or the SDEIS data for surface discharge SD004

is most accurate, but I do point out how the SDEIS mercury data needs to be broadened out to

minimize reliance on just one or two samples. Otherwise it is impossible to get a representative

sample and make scientifically and statistically sound decisions. Therefore, in this comment I

reiterate my strong recommendation to discontinue over reliance upon data from SD004.


5. The SDEIS includes an Assessment of Existing Pond Water and Groundwater Quality at the Tailings Basin that shows mercury seepage at nearly six times the Great Lakes standard for mercury discharges, yet this result is inexplicably not recognized or discussed further.

As noted elsewhere in these comments, the SDEIS reaches incorrect conclusions about mercury

seepage from the Tailings Basin. Generally those incorrect conclusions can be traced to

improper cherry picking of sample locations, as well as errors in calculations.

There is one place in the SDEIS where a comprehensive summary of current data has been

assembled to show the effect [of] passage through the existing LTVSMC tailings has on seepage

water quality. This information is compiled into Table 4.2.2-23, and is found at page 4-110 of

the SDEIS. I have replicated it with annotations on the following page of these comments.

Notably, unlike some of the datasets used in the SDEIS, Table 4.2.2-23 contains some of the

most current data available with regard to Tailings Basin discharges.

As explained at page 4-111 of the SDEIS, the assessment summarized on Table 4.2.2-23 is useful

to show the effect of passage of water seeping through the Tailings Basin. The first paragraph of

Page 4-111 states as follows:

Comparing existing pond water quality with water quality at the toe of the

Tailings Basin helps define the effect passage through the existing LTVSMC

tailings has on seepage water quality. Based on the parameters that were

monitored in the Cell 2E pond, it appears that passage through the LTVSMC

tailings reduces the average concentrations of arsenic, fluoride, and

molybdenum, although it is difficult to determine to what extent these

reductions are simply attributable to the effects of dilution. The concentrations

of several other parameters, such as calcium, manganese, nickel, and TDS,

increase as they seep from the tailings pond to the toe of the Tailings Basin.

The preparers of the SDEIS commented on how calcium, TDS, and manganese all increased

when passing through the Tailings Basin; and how fluoride, arsenic, and molybdenum go down.

However, there is no mention or analysis whatsoever of the most significant data point:

mercury has gone from 1.4 ng/L in pond water to 6.4 ng/L after passing through the Tailings

Basin.2 I have highlighted these respective contaminants in yellow, green and red.

These results should considered in the SDEIS, because they directly conflict with the conclusions

that mercury is not a contaminant of concern at the NorthMet Tailings Basin.

2 Note that the underlying data shows some unusually high readings for mercury that may reflect sampling or

computational errors. However, even when removing potentially erroneous sample results, the mercury levels are still above Great Lakes Initiative Standards at numerous locations and over numerous periods.

Supplemental Draft Environmental Impact Statement (SDEIS)NorthMet Mining Project and Land Exchange

4.2.2 WATER RESOURCES 4-110 NOVEMBER 2013

Table 4.2.2-23 Existing Pond Water and Groundwater Quality at the Tailings Basin

Constituent Units

Pond Water

Quality (Cell 2E)

Toe of Tailings Basin(GW-001,GW-006, GW-007, GW-008, GW-012

Surficial Aquifer)

General Parameters Mean

Groundwater Evaluation Criteria Detection Mean1 Range

Calcium mg/L 30 -- 62 of 62 83 21 to 211Chloride mg/L 23 250 61 of 61 18 1 to 30Fluoride mg/L 5.2 2 47 of 61 1


6. The SDEIS relies upon a faulty mercury sequestration test that predicts remarkably low mercury levels in Tailings Basin seepage, while ignoring a superior test that does not predict significant sequestration.

At numerous points in the SDEIS and supporting documents, reference is made to a bench study

conducted by NTS in 2006 that purports to show [T]he concentration of dissolved mercury in a

treatment flask containing process water and NorthMet tailings decreased from 3.3 ng/L to 0.9

ng/L over an eight hour period. SDEIS at page 5-206, As discussed below, this test had obvious

flaws and glaring mischaracterization of the collected data.

In contrast, the SDEIS entirely fails to even mention that a second carefully designed mercury

sequestration test was performed. This test concluded that there was no observable

diminishment when mercury-laden water passed through the simulated LTV/NorthMet tailings

combination. If anything, the test showed a slight increase in mercury levels. This thorough

study, despite having tremendous potential to quantify likely mercury discharges from the

combined Tailings Basin, is never so much as mentioned at any point in the SDEIS itself.

This is a situation where a very low-quality test with favorable results was prominently

presented in the SDEIS, while a high-quality test with unfavorable results was not even

mentioned. In view of the fact that mercury is the most serious contaminant in the St. Louis

River watershed to public health, the basis of this important research warrants further

examination. The tests are also important because the level at which the Tailings Basin

discharges mercury affects numerous other conclusions and design choices, in particular a large

number of alternatives that should be considered if mercury will be leaching from the NorthMet

Tailings at levels above 1.3 ng/L.

Details of the tests and their results are provided below.

6.1 The SDEIS relies on an 8 hour mercury sequestration test in a single flask to argue that NorthMet Tailings will retain mercury for hundreds of years, yet this test was so poorly designed, executed, and analyzed that it risks becoming an opportunity to attack the credibility of the entire SDEIS preparation process.

The SDEIS and supporting documents assert that researchers had undertaken experiments that

showed the NorthMet Tailings would capture mercury and prevent it from discharging from the

Tailings Basin. This test is cited as one of the grounds for being able to conclude that mercury

contamination would be below the Great Lakes Initiative standard. See page 5-206 of the SDEIS.

The test report was not available on the SDEIS reference disk, but I was able to receive a copy of

it from Ms. Lisa Fay at the Minnesota Department of Natural resources.

As detailed below, the test was undertaken for just eight hours and apparently with just one

sample. Amazingly, no effort was undertaken to try to replicate conditions in the Tailings Basin,

and even the flawed results were mischaracterized to state conclusions that are clearly refuted

by the test data.


Briefly, here is a summary of the test and results:

Two shake flasks (Jug C and Jug D) were filled with water that was spiked with mercury to obtain

about 3.5 ng/L of mercury in the water. One flask had PolyMet tailings (Jug C) in addition to the

mercury-spiked water, and was meant to test mercury absorption by tailings. The other flask

just had the water (Jug D), and served as the control. The flasks were shaken for 8 hours, and

samples removed and analyzed over time.

The results are reproduced below:

From these results, NTS concluded that The results showed that mercury removal by

adsorption to PolyMet tailings occurs rapidly and remains stable throughout the conditions of

this experiment. NTS 2006 Report, page B-2, emphasis added.

What is most peculiar to me about these test results is the conclusion that mercury

sequestration remains stable. In fact, over the last 4 hours of the test, the mercury levels

nearly doubled, and are on a trajectory to exceed the GLI Standard in approximately 4 more

hours.

Besides this obvious misstatement of the test results, a few other flaws are obvious just in the

way the test was conducted: First, it looks like just one sample was tested for each of the

control and the tailings. Second, there was no effort to replicate in situ conditions, such as

redox conditions, oxygen levels, biological factors, etc. Third is the obvious shortcoming of using

an 8 hour test on a centuries long problem. Another strange aspect of the results is that it


reports testing was done on Jug C and Jug D. What might be shown in Jugs A and B? Were they

analyzed? If so, what does their data show?

6.2 A much better test did exist, but the results are not even mentioned in the SDEIS. Those tests show that the PolyMet Tailings combined with NorthMet tailings provide no net mercury sequestration.

In July, 2007, some four months after the short NTS flask test mentioned above, PolyMet Mining

Inc. did receive a report on the Tailings Basins ability to sequester mercury. This test,

conducted over many months, sought to investigate potential chemical processes that can be

expected between the tailings basins. SRK 2007c at page 15. The consultants who prepared the

test worked with the Minnesota DNR3 to provide a column design reproduced below:

This design and experiment had many major improvements over the earlier NTS report: it

sought to replicate travel through both the NorthMet tailings and the existing LTV tailings, it

sought to replicate subterranean conditions, such as oxygen levels, and it ran for much longer

(at least a year).

This test concluded that [t]here were no clear increasing or decreasing mercury concentration

trends along the flow path through the LTVSMC tailings. SRK 2007c at page 31.

It is peculiar that this test was not disclosed in the SDEIS, while an 8 hour test under much less

relevant conditions was included, and used as support for the conclusion that mercury

discharges will be below the Great Lakes Initiative level.

6.3 The SRK test that showed no mercury sequestration should have been included in the SDEIS, because it is on its face far more probative than the NTS eight hour test.

3 SRK Consulting Report at Page 16.


The NorthMet SDEIS asserts that one of the fundamental long-term mechanisms for mercury

control at the NorthMet Tailings Basin is removal of mercury by the pre-existing LTV taconite

tailings. This mechanism is relied upon repeatedly in the SDEIS itself, as well as the supporting

documents.

This mechanism was also proposed in the original DEIS, but was objected to as lacking scientific

integrity by the EPA, which requested that further analysis be provided to support this mercury

removal mechanism. See page 11 of the EPA Detailed Comments to the NorthMet Project

DEIS. Despite the EPAs express request for further support of this theory, the SDEIS fails to

provide further support, and merely restates the previously challenged analysis.

To correct this deficiency the SDEIS should address why preparers believe the 8 hour shake test

is a better predictor of long term tailings basin mercury sequestration than the year-long column

testing.


7. The site-specific sampling of mercury at the Tailings Basin is consistent with prior taconite tailings seepage research

At various points in the SDEIS4, reference is made to prior research by Minnesota Department of

Natural Resources scientist Michael Berndt that looked at mercury releases from mining

operations in Minnesota, including from stack emissions and tailings basin seepage. The SDEIS

relies especially on a 2003 paper by Mr. Berndt entitled Mercury and Mining in Minnesota,

submitted as a final report to the Minerals Coordinating Committee in June of 2003, and revised

in October of 2013. SDEIS reference Berndt 2003.

As discussed below, the interpretation that NorthMet Tailings Basin seepage will be above Great

Lakes Initiative standards is consistent with the data and conclusions of the 2003 report.

7.1 Berndt 2003 included data from the existing LTV tailings basin, and the seepage had a total mercury concentration of 2.44 ng/L

Table 4 of Berndt 2003 is reproduced below. The total mercury level from the LTV tailings basin

is highlighted in yellow, and is 2.44 ng/L. This measure of LTV tailings basin seepage was

collected from an earlier MNDNR study5, and represents perhaps the only mercury measure

made with a low detection level during operation of the LTV tailings basin.

4 See, in particular, SDEIS page 5-205

5 See page 48 of Berndt 2003.


This level of mercury contamination in LTV tailings seepage is consistent with some of the other

data that is available. See, e.g., the chart entitled Tailings Basin Surface Discharges with

regard to Comment 3 above.6

7.2 The composite SDEIS data for the Tailings Basin actually aligns closely to the finding of Berndt.

Comment 3, above, looked at a comprehensive set of mercury data for the Tailings Basin

seepage. The results showed a composite average of 2.5 ng/L, which is very close to the LTV

measure reported in Berndt of 2.44 ng/L at the LTV site.

7.3 The observed Tailings Basin mercury seepage is within the range expected by Berndt 2013, even though it is above the Great Lakes Initiative standard.

Table 4 of Berndt 2013 shows seeps and monitoring wells at various Minnesota taconite

facilities ranged from .72 to 2.9 ng/L of total mercury. The composite measure of about 2.5

ng/L, reported above in Comment 3, fits within this observed range from Berndt. The levels are

above Great Lakes Initiative standards, but still within ranges one would foresee from Berndt.

7.4 Even if the NorthMet Tailings Basin reduces the concentration of mercury in the seepage, that seepage can still exceed Great Lakes Initiative standards, and would still be in violation of the Great Lakes Initiative levels.

There is discussion in the SDEIS that the Tailings Basin mercury discharges will not be an issue because the discharge concentrations will still be less than the levels in either precipitation or the tailings basin pond water. This statement seems to apply that reduction in mercury levels in the Tailings Basin is sufficient, as opposed to actually meeting the Great Lakes Initiative requirements.

Berndt 2003 accurately states that:

It is important to note that just because an industry discharges water with a concentration that is less than that of the water it takes in does not mean it will meet water quality standard

Berndt 2003 at page 13.

In the present case that is exactly what seems likely to happen with the NorthMet Tailings Basin:

water may come out of the Tailings Basin at a mercury level lower than it went in, but will still

violate the Great Lakes Initiative.

6 Although this measure used in Berndt 2003 was for only one data point, it should be noted that Berndt

2003 used only a small number of samples for each measured site (see Table 4 from Berndt 2003,

reproduced above).


7.5 Even if the Tailings Basin mercury concentrations are reduced relative to influent, the increased flow of water through the Tailings Basin will significantly increase total mercury discharges.

The NorthMet Tailings Basin is expected to have at least twice as much seepage water

discharged during operations than is currently seeping from the Tailings Basin. Even if one

assumes the concentration of mercury in the Tailings Basin seepage will not change, the total

mass of mercury discharged will be significantly increased, likely by double or more.

7.6 Efforts to reduce atmospheric precipitation, especially from coal burning sources, will likely diminish background mercury loading dramatically in coming years, leaving the NorthMet Tailings Basin as a larger relative source of mercury to the Embarrass River and St. Louis River watersheds.

At the present time significant mercury loading into the Embarrass River and St. Louis River

watersheds occurs as a result of atmospheric deposition, much of it from coal plants. In fact, an

estimated 70 percent of atmospheric mercury deposition in Minnesota comes from

anthropogenic sources, including burning coal and improper disposal of fluorescent lights.

Efforts are underway in Minnesota, the broader United States, and outside the U.S. to reduce

mercury emissions. Reductions in coal burning will likely lead to significant reductions even in

the near term as increasing amounts of electricity generation switches from coal to natural gas.

It is likely that atmospheric mercury deposition reductions will continue for many decades, and

the amount of atmospheric deposition of mercury in the Embarrass River will decline. What

may not decline, due to the tremendous amounts of mercury now held within the existing

tailings basin at the NorthMet site, is the amount of mercury discharged from the Tailings Basin

in coming centuries.

Without adequate efforts to prevent mercury seepage and release at the Tailings Basin, the

likely result will be a circumstance where in coming decades and centuries the NorthMet project

becomes a larger and larger share of mercury contamination in the Embarrass River and St.

Louis River watersheds.


8. The Water Treatment Pilot Test data shows profound sampling irregularities that raise serious concerns about the adequacy of the protocols implemented and the accuracy of the test results obtained.

In view of the relatively short timeframe available to review thousands of pages of documents, I

have not spent extensive time reviewing sulfate levels at the NorthMet site, or sulfate removal

from the WWTP and WWTP Pilot Test.

However, I would be remiss in not pointing out that there appears to have been a very serious,

repeated error in the collection and analysis of sulfate data from the WWTP Pilot Test. The

evidence is quite strong that a serious sampling or analytical breakdown occurred during the

Pilot Test as it relates to sulfate levels in the test influent, and perhaps other contaminants of

concern.

Figures 5 and 6 from the Pilot Test Report are reproduced below, and reveal the reasons for

serious concern:

First, in looking at Figure 5, notice that surface discharge SD004 has relatively constant levels for

the three measured parameters: Sulfate, Total Hardness, and TDS. In contrast, a new well

installed in 2011 for the pilot test showed remarkable variation in sulfate levels, fluctuating

almost exactly by 400 percent either at about 100 mg/l, or 400 mg/l. There is essentially

nothing in between. TDS and Total Hardness fluctuate on the same days, but at different ratios

that are closer to 200 percent. Such readings are inexplicable from a groundwater well.


Second, looking at Figure 6, the issue becomes becomes even more concerning, because on the

same exact dates that sulfate, total hardness and TDS were changing, the iron and manganese

concentrations remained all but constant from the same sources.

This combination of consistency in some parameters, but extreme volatility in other parameters,

all from the same source and the same day, indicates likelihood that serious errors have been

introduced into the data. There is no evident reason why such variation would occur naturally.

If these variations were naturally occurring in the well water, they would expected to be more

random in nature. Also, if groundwater dilution were to be a factor, such as from rainfall, then

the dilution would be expected to be somewhat uniform across the different parameters. In

other words, one would expect sulfate, iron, manganese and the other materials to have been

uniformly diluted, other than perhaps small changes for solubility.

It seems very possible that the errors occurred after sample collection, maybe during analysis of

the samples, when possible errors in dilution or peak calculations occurred on different samples

destined for different tests.

The overwhelmingly strong indication of errors in the samples from these sources is of course

very concerning. Due to the presentation of the data in a graph, it is possible to spot the errors.

What concerns me even more is what other data from the Pilot Test, and the SDEIS, contains the

same errors, but have gone undetected? To put it simply, what other data sets are 400 percent

too high, 400 percent too low, or just right?


Unfortunately this rather obvious error was not detected earlier, because it calls into question

fundamental questions as to accuracy of any data sets in the WWTP Pilot Test. In combination

with the improper confusion of ng/L and ug/L of mercury in the Tailings Basin (see Comment 1,

above), there is reason to be concerned about the fundamental integrity of the very data that is

being used to make decisions in the NorthMet project.

As stated elsewhere in these comments, I strongly recommend that an independent third party

be retained by PolyMet Mining, Inc., or the lead agencies, to audit the data. This will be a

significant undertaking, but would allow regulatory bodies the ability to make decisions with

confidence that at least the information used for the decision making was sound.

I would be willing, at the request of the MDNR or other NorthMet project participants, to

undertake a further initial review of other SDEIS datasets to assist a third party audit.


9. The SDEIS improperly locates one of the Tailings Basin sample locations at Unnamed Creek, which raises further concern about data integrity in the SDEIS process.

The most important sample locations for Tailings Basin seepage are arguably the NPDES permit

discharges. Proper sampling of these locations is critical to assessing contamination from the

Tailings Basin, including mercury, sulfates, etc.

Reproduced below is a portion of SDEIS Figure 4.2.2-9. Inexplicably, it has the wrong location

for NPDES discharge MN0054089-SD-001 (SD001). The label is placed at a different sample site

on Unnamed Creek, but actually it should be in the west drainage ditch of the Tailings Basin.

This discrepancy should be investigated to determine when the error was introduced into the

figure, and whether or not the error may have resulted in sampling of water from erroneous

locations. Thus, is there any risk that this error, or a similar error, was present on other maps

used by field technicians when collecting samples? If an individual had incorrect map data, they

would have collected samples from the wrong location and subsequently mislabeled those

samples. This could explain WWTP Pilot Test data issues if samples were collected in the

incorrect location.

I recommend a review of the field instructions and materials to evaluate the potential for

erroneous sampling. Note, if technicians collected GPS coordinates at the time samples were

collected, it should be possible confirm accuracy of the sample locations.


10. In view of the identified serious errors in NorthMet data sets as they relate to the Tailings Basin site, a comprehensive audit of NorthMet data should be undertaken.

I have had a very limited amount of time, and limited resources, to review NorthMet Project

data, and my review has primarily been focused on just a small portion relating to Tailings Basin

impacts. Despite this very narrow focus of my inquiry, I have identified the following serious

flaws and errors in the NorthMet data set:

10.1 The Tailings Basin mercury contamination calculations confused nanograms and micrograms.

As noted above, the Tailings Basin mercury contamination calculations confused nanograms and

micrograms. The result is a profound misstatement of mercury seepage levels at nearly half of

the Tailings Basin sample locations. The error was of serious significance because it calls for a

revision of Tailings Basin discharges from being below Great Lakes Initiative levels to above

Great Lakes Initiative levels.

See Comment 1 for more explanation of this problem.

10.2 The Waste Water Treatment Plant influent water has a serious error in either sample collection or data analysis.

The SDEIS relies upon a WWTP Pilot Test that shows serious errors in testing of the influent

water. At a minimum these errors prevent analysis and operation of the Pilot Test system

because the influent was not properly characterized. In a worst case scenario, other samples

were also erroneously collected or analyzed, but those errors have not (and possibly cannot) be

identified.


10.3 One of the most important sample locations at the NorthMet site is wrongly located on a map.

The SDEIS contains at least one indication of a critical sample location being shown in an

incorrect location. It is not clear whether other similar errors have been made, or whether this

error impacted sample collection and analysis.


10.4 Due to the critical nature of the NorthMet SDEIS, and the centuries-long impacts of the NorthMet Project, an audit is necessary.

A thorough review of the datasets and collection details should be undertaken to confirm

integrity and accuracy. A third party competent to perform such a review should be retained,

because an independent review is more likely to find serious errors than having the existing

team of consultants review their own work.


I would be willing, at the request of the MDNR or other NorthMet project participants, to

undertake a further initial review of other SDEIS datasets to assist a third party audit.


11. In view of the foregoing comments with regard to mercury contamination, statements made in the NorthMet SDEIS that the Tailings Basin is expected to discharge mercury at levels below Great Lakes Standards should be removed from the SDEIS.

The following statements, among others, should be modified as below (or in accordance with alternative language that is accurate):

11.1 At ES-36, in the Executive Summary, edit as follows, or with other language to make the statement accurate and complete:

Mercury is another constituent of concern, primarily because many of the lakes and rivers in the area are currently classified as impaired waters by the MPCA due to elevated mercury content in fish tissue. The NorthMet Project Proposed Action is located within the Lake Superior Basin and would be subject to the Great Lakes Initiative (GLI) mercury discharge standard of 1.3 nanograms per liter (ng/L). . . . The mercury concentration in seepage from the Tailings Basin is anticipated to be above below the GLI standard. . . .

11.2 At Page 5-8 of the EIS, edit as follows or with other language to make the statement

accurate and complete, and follow up with review of Tailings Basin alternatives in view of this correction:

There would also be mercury in the tailings, although about 92 percent of the mercury in the ore is predicted to remain in the ore concentrate. However, and the mercury concentration in seepage from the Tailings Basin is expected to be greater than less than the standard.

11.3 At page 5-206 of the EIS, edit as follows or with other language to make the statement accurate and complete, and follow up with review of Tailings Basin alternatives in view of this correction:

Therefore, the total mercury concentration in seepage from the Tailings Basin is expected to be greater than less than the Great Lakes Initiative standard of 1.3 ng/L.


PAULY COMMENT SECTION 2

The errors and omissions in the Tailings Basin mercury dataset, and the selective consideration of only favorable mercury test results, have (1) resulted in a defectively designed and tested Waste Water Treatment Plant, which should be corrected with a supplemental comprehensive pilot test, and (2) have resulted in design of a Tailings Basin containment system that fails to consider likely significant transport of methylmercury into the Embarrass River watershed.


12. The underestimation of mercury contamination in Tailings Basin seepage water resulted in design and testing of a WWTP that has no demonstrated ability to economically remove mercury from the seepage water.

In 2012 PolyMets consultants undertook a pilot test with the objective of demonstrating that

the WWTP can collect sufficient information to demonstrate that a cluster of technogies,

focused on reverse osmosis (RO), can demonstrate reliable satisfaction of water quality

objectives, support the design of the WWTP, refine capital and operating costs, and support

performance guarantees and system warrantees.

As discussed below, the Pilot Test should have addressed all four of these objectives as it relates

to mercury, but unfortunately the Pilot Test failed to provide even a rudimentary test and

analysis of mercury removal.

Only a very few sentences in the Final Pilot Testing Report (SDEIS Reference 2013g) address

potential mercury removal. Page 40 to 41 provides the entire summary of the conclusions that

could be reached from the pilot test, a review of scientific literature, and an inquiry to the

membrane supplier. The entirety of the mercury removal discussion fits on four lines:

Mercury removal by RO is highly variable and dependent upon speciation and

membrane selection. For these reasons, its removal is difficult to quantify.

However, mercury concentrations in the WWTP influent during operations

were not estimated by the GoldSim model.

PolyMet 2013g at page 40 to 41. Thats it. In other words, as to the question of mercury

removal: We dont know, and we didnt even try to find out.

It is inexcusable that a pilot test collecting seepage water from a 60 year old unlined tailings

basin, known to discharge mercury laden water at two times the Great Lakes Standard, did not

even explore mercury removal at a pilot plant that is supposed to clean water for hundreds of

years!

A deeper dig into the Final Pilot Testing Indicates even more significant issues, which I

summarize below:

12.1 The Pilot Test Report Shows mercury removal is likely to be from 22 to 99.9 percent.

Besides the very brief conclusions presented above, the discussion of mercury is given a total of

four sentences on page 39 of the Final Pilot Testing Report. I reproduce them below in their

entirety:

Mercury removal by RO membranes is highly dependent on the type of

membrane used. Mercury rejections ranging from 22 to 99.9% have been

reported. The chemical state of the mercury is also an important factor in

mercury removal. Urgun-Demirtas et al. (Reference (19)) (sic), found that


mercury in the colloidal or particulate form was easily removed but that free

mercury was removed at a lesser rate. Rejection values for organic mercury by

RO membranes could not be found in the peer reviewed literature, but one RO

membrane vendor (DuPont) and the University of Nevada Cooperative

Extension claim that methylmercury cannot be removed across a RO

membrane.

Paul Dilallo of GE indicated in a personal communication (Reference (8)) that the

rejection for mercury is estimated to be approximately 70%.

These four sentences are what we have to go on to figure out how well the WWTP might

remove mercury. Here is what we know:

12.2 Mercury removal could be between 22 and 99.9 percent, but no one knows and no one has asked.

We know that mercury might be removed by the WWTP. Or it might not be removed. There

are two ways to find out, either do Comprehensive Pilot Test based upon more realistic

conditions, or wait to see what comes out of the WWTP in a couple decades when the

maximum discharges start to occur.

12.3 Mercury contamination is highly dependent upon species, and PolyMets own vendor states that methylmercury cannot be removed across an RO membrane.

Methyl mercury is, far and away, the most dangerous form of mercury. It is the form that is

most bio-available, and most likely to accumulate in the tissue of fish and infant humans.

According to the best information assembled by PolyMet, the WWTP as designed will not

remove methylmercury. Instead it will simply be going out with the discharge water, where it

will be part of the makeup water directed into the Embarrass River.

Most disturbing about this issue is the fact that if the WWTP selectively removes colloidal or

particulate mercury (as at least one reference predicts), then what will be left will be the

methylmercury, which wont be removed. The result is the potential for technical satisfaction of

the Great Lakes Initiative standard of 1.3 ng/L of mercury in WWTP discharges, while having this

1.3 ng/L of mercury be disproportionately methylmercury. Under such a scenario the WWTP

will be in compliance with regulatory standards while actually discharging the most toxic form of

mercury in abundance.

12.4 The RO membranes that best remove mercury also have unacceptably low system recovery rates.

A Supplemental Comprehensive WWTP Pilot Test is also necessary because PolyMets own

literature review shows that even if an RO membrane can remove mercury, it may not do it with

adequate system recovery. Specifically, the Final Pilot Testing Report includes Table 29, which

shows a summary of Metals Removal Literature Review Summary.


Note that mercury removal is reported to be greater than 98 percent in Reference 16,

but the system recovery is just 50 percent, which means that only about half the water

is recovered as permeate, with a very high volume of high-mercury retentate. Even this

is measured only using a pilot level test.

These issues, such as rejection rate and system recovery are non-trivial, and can

dramatically impact long term performance and cost of mercury removal. For example,

if system recover rates are low, a two-phase system might be needed, which would

significantly increase capital and operating costs. Alternatively, it may be necessary to

have different systems for mercury removal and sulfate removal if a single treatment

system cannot be found that adequately removes both contaminants.

In summary, we simply do not have enough information to evaluate a multi-century

waste water treatment plant, either from a technical or financial point of view. A

comprehensive pilot test should be performed, and it should be directed both to

technical viability, as well as financial predictions. In view of the known seasonal

variations in contaminant streams (see, e.g., report of Michael Berndt discussed below,

showing large seasonal fluctuations in methyl mercury discharges at the toe of a

taconite tailings basin), I recommend that such test run for at least from the start of one

summer through the end of a following summer.


13. The WWTP Pilot Test report also indicates serious flaws in the sulfate pilot testing.

In an earlier comment I expressed serious concern over the integrity of the data set from the

WWTP Pilot Test. The reported influent levels for sulfate concentrations show that error was

introduced into sample collection and/or analysis process. The error seems to be on the order

of 400 percent, but isnt clear if influent levels have been overstated by 400 percent or

understated by 400 percent. In other words, no one really knows what the influent sulfate

levels were.

In addition, just as alarming, is the potential that the effluent results may have the same errors,

or even other unidentified errors. This is not a trivial question, in particular because the final

step of water treatment, VSEP process, had permeate level reported to be above 10 mg/l, and

about 6 to 60 mg/l. See Figure 12 of the WWTP Pilot Test report. So, should those levels be 24

to 240 mg/L? Or maybe they should be about 1.5 to 15 mg/l. Preparers of the SDEIS should

review sample records, analytical data, and related material to ascertain the accuracy and

integrity of the data set.


14. A Comprehensive WWTP Pilot Test should be conducted in a manner that provides meaningful information as to likely costs.

As noted above, the WWTP Pilot test failed to even look at mercury as a substance to be

removed from the NorthMet site, and also failed to even properly monitor sulfate levels in the

influent. Other contaminants, such as aluminum, were also not properly analyzed during the

Pilot Test.

The need for a supplemental WWTP pilot test is clear from a technical viability standpoint, but is

also necessary from a financial viability standpoint. The RO literature is clear that each site is

different, and the costs of systems really cant be estimated with insufficient information about

feed water and likely membrane performance.

A good example of that information is a 2013 Report from the U.S. Department Of Energy

entitled Reverse Osmosis Optimization (available from comment author upon request), which

states as follows:

The cost of optimizing an RO system is influenced by many parameters that are

specific to the application and operation of the system, such as feed water

quality, membrane type, system configuration, and purity requirements.

Therefore, to determine the costs and financial benefits of optimization options,

the financial analysis must take into account the site-specific nature of the

technology.

Reverse Osmosis Optimization, by Pacific Northwest National Laboratory, page 19

(emphasis added).

These are non-trivial issues for which the SDEIS contains inadequate information, which is quite

problematic for a WWTP that is expected to process 630,000 gallons per day of water for

hundreds of years.


15. The SDEIS incorrectly states that the Pilot-testing has indicated that treated effluent from the Plant Site would meet water quality standards for all regulated constituents.

As discussed above, the WWTP Pilot Test did not determine whether mercury would be

removed by the WWTP. The SDEIS should be updated to reflect this fact. A partial list of

suggestions is provided below:

15.1 Table 5.2.2-28 should be modified to include mercury as a target.

Table 5.2.2-28 provides the WWTF preliminary water quality targets. Mercury is not

included but should have been included.

After mercury is added as a target effluent, design of the WWTF should be evaluated for

mercury removal, and a review should be made of SDEIS analysis and conclusions that

presumed mercury did not need a WWTF water quality target. This review should

include evaluation of alternatives that were prematurely eliminated.

15.2 Page 5-125 should be modified to clarify that mercury removal was not tested in the pilot plant. Suitable language could include:

Table 5.2.2-28 presents the target WWTF effluent concentrations for the different

mine phases. Pilot-testing of a WWTF with RO demonstrated that all of the target

closure effluent concentrations could be achieved with the planned WWTF design, with

the possible exception of mercury, for which no pilot testing has been undertaken and

for which significant disagreements exist on viability of removal by RO processes.

15.3 Page 5-203 of the SDEIS should be amended to include statements from the Pilot Plant Test that removal of mercury using RO technology is uncertain. Potential language to consider is:

It should be noted that the West Pit overflow would be treated by the WWTF using RO

technology prior to discharge, and the RO process is known to remove mercury.

However, as indicated in the Pilot Test Report, there are disagreements in the literature

about how much mercury can be removed, and the most dangerous form of mercury

(methylmercury) has been reported as unremovable using RO methods.

15.4 Table 5.2.2-52 should be modified to provide correct information of estimated mercury concentration of the combined inflows to the Plant Site WWTP

Table 5.2.2-52 describes Mercury Concentration from Tailings Basin seepage water and

Runoff (not interacting with tailings) to be 1.1 ng/L, which is below Great Lakes standard

levels. In fact, mercury levels for these two sources will likely be higher than these

estimated levels.


Correcting this error is essential because these two sources of inflows are expected to

account for over 80 percent of the water inflows into the WWTP, and will impact

feasibility and design of the WWTP, as well as long term costs to operate the WWTP.

For the assistance of the SDEIS drafters, current table 5.2.2-52 is reproduced below with

the erroneous unsupported information highlighted in yellow. Also provided below is

alternative calculations that are based upon Comprehensive Tailings Basin Water

Sampling data of Pauly Comment 3:

Table 5.2.2-52 Estimated Mercury Concentration of the Combined Inflows to the Plant Site

WWTP

Stream Flow Rate (gpm)

Mercury Concentration (ng/L)

Total Mercury Flow (ng/yr)

Seepage Water 1,498 1.1 3.3E+09

Runoff (interacting with tailings) 294 1.1 6.4E+08

Runoff (not interacting with tailings)

72 3.5 5.0E +08

Tailings Basin pond dewatering 365 2.0 1.5E+09

Combined stream 2,229 1.3 5.9E+09

When corrected, the numbers become approximately as follows:

Recommended Table 5.2.2-52 Estimated Mercury Concentration of the Combined Inflows to

the Plant Site WWTP

Stream Flow Rate (gpm)

Mercury Concentration (ng/L)

Total Mercury Flow (ng/yr)

Seepage Water 1,498 2.5 7.5E+09

Runoff (interacting with tailings) 294 2.5 1.5E+09

Runoff (not interacting with tailings) 72 3.5 5.0E +08

Tailings Basin pond dewatering 365 2.0 1.5E+09

Combined stream 2,229 2.5 1.0E+10

It should be noted that the mercury discharge numbers in recommended Table 5.2.2.52

correspond quite closely with the only known high quality sample of Tailings Basin

discharges when the Tailings Basin was last receiving tailings (Berndt 2003), and also

align quite closely to current Tailings Basin discharges when a comprehensive sample


analysis is undertaken as opposed to the very narrowly focused sample sets proposed in

the SDEIS (and discussed earlier).


16. The SDEIS proposes a perimeter wetland that will receive sulfate and mercury, and has the potential to lead to significant methylmercury production and transport into the Embarrass River watershed.

One of the most significant changes in the Tailings Basin since the DEIS was prepared is a

proposal to construct a perimeter cutoff wall and drainage system around the north and west

sides of the Tailings Basin. The objective of capturing discharges from the Tailings Basin has

merit, but the proposed plan is seriously flawed because the cutoff wall and drain pipe are set

back over 250 feet from the edge of the Tailings Basin, so as to form a large perimeter wetland

of up to 160 acres in size. As discussed below, due to the nature of the soil in this wetland, the

majority of mercury and sulfate laden seepage will be delivered into the wetland, as opposed to

going directly to the drain pipe system.

The potential extent of this perimeter wetland is shown in the figure below, which is from Barr

2013F, but has been highlighted in yellow to show the perimeter area between the Tailings

Basin and drainage pipe.

Wetlands have been known for some time to be prime locations for methylation of mercury

from its inorganic form to its far more hazardous organic methylmercury form. Recent research

in Minnesota has shown that some of the highest methylmercury levels ever recorded have

been observed in restored wetlands. In addition, recent Minnesota DNR research at tailings

basins has shown that seepage water from tailings basins has particularly high methylmercury

concentrations during seasons of heightened biological activity.

As discussed below, the proposed Tailings Basin capture system has the potential to create very

high levels of methylmercury. Once created, the methylmercury will be able to exit the capture


area either by 1) biological transport into the Embarrass River watershed, or 2) passing through

the Waste Water Treatment Plant, which has not been designed or tested to remove it.

These concerns are detailed below.

16.1 The unique nature of the soils at the NorthMet site result in delivery of tailings seepage to the wetlands, rather than to the drainage pipe.

The Containment System called for in the SDEIS is shown in cross section below, which is taken

from Figure 4 of reference PolyMet 2013f. This figure is a useful one for evaluating containment

system flow during mine operations because it is taken on the north end of the Tailings Basin

where the greatest amount of discharge is predicted.

The black lines show the flow path of the seepage according to NorthMet Project Modeling.

Notably, according to the model, 78 percent of the seepage water is delivered to the wetlands,

while only 22 percent of it is delivered to the Containment System Drain Pipe. The reason for

this flow path, according to SDEIS documents, is that the relatively low hydraulic conductivity of

the soils forces the water to the surface, where wetlands will likely expand and proliferate.

Within these large perimeter wetlands, the ideal conditions for mercury methylation are likely

to occur: abundant mercury, sulfate, dissolved organic compounds (DOC), and water.

The SDEIS entirely fails to consider what will happen when the mercury, sulfates, DOC and water

combine in these perimeter wetlands. The SDEIS should be modified to consider the following

possible impacts:


16.2 A recent Minnesota study showed concentrations of methylmercury in restored wetlands had some of the highest in published literature, suggesting creation of wetlands to receive a mercury and sulfate mixture is a serious concern for the Embarrass River ecosystem and downstream inhabitants.

In 2013 the USGS released a study on mercury methylation in northwestern Minnesota, and

found stunningly high levels of methylmercury. Key portions of that report are reproduced

below, with emphasis added:

Compared to concentrations in stream sediment samples collected throughout the United States, Glacial Ridge National Wildlife Refuge wetland sediment samples contained typical total-mercury concentrations, but methylmercury concentrations were nearly twice as high. The maximum concentration measured in Glacial Ridge National Wildlife Refuge wetland water approached the highest published water methylmercury concentration in uncontaminated waters of which we are aware. However, the upper quartile of water methylmercury concentrations is similar to concentrations reported for some impoundments and wetlands in northwestern Minnesota and North Dakota. Methylmercury concentrations in sampled wetlands were much higher than those from typical lakes or flowing streams throughout the United States. The high concentrations of methylmercury measured in sampled wetlands indicate the potential for substantial methylmercury concentrations in aquatic biota and wildlife that consume those biota. These wetlands also are a methylmercury source for downstream lakes and rivers. The high concentrations of methylmercury in water, its bioaccumulation potential, and its known toxicity in aquatic birds and food webs highlight a need to assess methylmercury in the biota within these ecosystems. Better understanding of factors that control methylmercury production concentrations within aquatic food webs in ecosystems of the Glacial Ridge National Wildlife Refuge would enable resource managers to better understand and manage risk to wildlife.

Scientific investigations Report 2013-5068, Mercury in Wetlands at the Glacial Ridge National

Wildlife Refuge, Northwestern Minnesota, 2007-2009. Emphasis added. Copy available from

comment author upon request.

16.3 Recent DNR research also shows that taconite tailings basins can have particularly high methylmercury releases that coincide with times of greatest biological activity in wetlands This research should be considered in evaluating impact of wetlands positioned between the Tailings Basin and containment system drain pipe.

Another very serious issue as it relates to methylmercury releases is that recent MNDR research

shows that discharges from a taconite tailings basin had a seasonal spike in methylmercury

discharges during the summer months when most wetland biological activity occurs.


This research is compiled in Sulfate and Mercury Cycling in Five Wetlands and a Lake Receiving

Sulfate from Taconite Mines in Northeastern Minnesota, Berndt and Bavin, 2011. Reproduced

below is a portion of Figure 9 of Berndt and Bavin, showing the seasonal changes in total

mercury and methylmercury from May to October.

May to October

The excerpt above shows how total mercury was essentially constant from May to October, but

the amount of methylmercury increased significantly during summer months. It is not clear if

more methylmercury is being produced during the summer months, or if it is simply being

released in greater quantities, but this increase should be of great concern to anyone proposing

a Tailings Basin perimeter wetland. Should this effect also hold true at the NorthMet Tailings

Basin, levels of methylmercury must be contemplated, especially during summer months.

A further concern raised in Berndt and Bavin with regard to the examined wetland, at a taconite

tailings basin toe similar to the NorthMet Tailings Basin, is that the mechanism for the increases

in methylmercury are not obvious nor necessarily fully understood. Berndt and Bavin at page 13.

It may be that increases in sulfate reduction in summer months lead to accelerated

methylmercury production. It appeared that the methylmercury increased across a backdrop of

continuous amounts of sulfate reduction and

northmet comments by daniel pauly

Documents

tailings basin mercury

tailings basin seepage

tailings basin discharges

tailings basin dataset

best data

sdeis drafters

total mercury

mathematical errors