1 

ATTACHMENT 2: A REVIEW OF THE AVAILABLE DATA ON THE 

EFFECTIVENESS OF AMALGAM SEPARATORS 

I. INTRODUCTION

The ADA has collected data on whether amalgam separators reduce effluent 

mercury from a number of publicly available sources (including information from the National 

Association of Clean Water Agencies (“NACWA”) study). These results are summarized below. 

A more systematic review of this data is necessary before definitive conclusions can be drawn, 

II. EXECUTIVE SUMMARY

Although the database cannot be viewed as definite, several general observations 

can be made. 

First, clearly, installation of amalgam separators shifts the primary point at which 

amalgam is removed from the sewerage treatment plant, where professional environmental 

engineers handle the material, to the dental office (where technical experience with mercury is 

more limited). 

Second, in general, the levels of mercury in biosolids (see Table 1: Comparison 

of average biosolids concentrations and EPA biosolid limits in the main ADA comments) and the 

effluent (see Figures 1 through 13, below) are relatively low. The mercury concentrations in 

treatment plant effluent, in particular, are often barely above the detection limit. The low 

concentrations and the inherent variation in mercury concentrations in effluent make 

determination of trends difficult. Given the extremely low levels of total mercury in the 

treatment plant effluent, the fluctuations may simply be analytical variation or variation in 

background levels of mercury. 
2 

Third, the data does support the effectiveness of the treatment plant in removing 

mercury from influent. 

Fourth, the data indicates that total mercury levels in biosolids and treatment plant 

influent can decrease as a result of the installation of amalgam separators. The issue (discussed 

in the body of these comments) is whether further reductions of mercury levels in biosolids that 

are already well below EPA biosolid limits significantly reduces the release of mercury into the 

environment, specifically the release into surface water. 

Fifth, a visual review of the effluent data indicates that there is no clear pattern of 

decreases in treatment plant effluent following the installation of amalgam separators, and some 

data may suggest an increase in the effluent. Neither the individual presentations that interpreted 

this municipal data nor the NACWA study correlated the change in mercury concentration over 

time with separator installations. 

Sixth, the mercury concentrations in treatment plant effluent, in particular, is often 

near to the detection limit. The low concentrations and the inherent variation in mercury 

concentrations in effluent make determination of trends difficult. Given the extremely low levels 

of total mercury in the POTW effluent, the fluctuations may simply be analytical variation or 

variation in background levels of mercury. 

In summary, there are no downward trend in the mercury concentration of 

effluent easily observable after installation of amalgam separators. However, a more detailed 

statistical analysis of the existing data (with an attempt to correlate the timing of the institution of 

the pre-2007 Best Management Practices (“BMPs”) for amalgam waste, amalgam separators, 

another mercury reduction activities at the sewerage treatment facilities) would probably be 

useful. 
3 

III. THE MEASURE OF EFFECTIVENESS

The issue of whether amalgam separators are effective depends on what measure 

one uses to define “effectiveness.” There is no debate that amalgam separators installed in dental 

offices would prevent more than 6 tons of amalgam from entering sewerage treatment plants 

annually. As a result, the concentration of mercury in sewerage treatment plant influent and 

biosolids (where the vast majority of mercury from amalgam is collected) will decrease after 

separators are installed, so long as other sources are much higher than the dental office 

contribution, thereby masking any decrease. 

However (as discussed in Attachment 1 to the ADA Comments), the net benefit to 

the environment is far less than this 6 tons because sewerage treatment plants remove more than 

95% of amalgamated mercury. Also, typically, the protecting the environment does not include 

the interior workings of industrial plants or municipal wastewater treatment plants (see 

discussion in the ADA Comments). 

The ADA considers that the appropriate measure of “effectiveness” for the 

pretreatment rule is the reduction of the mercury concentration in the effluent from sewerage 

treatment plants discharged into surface water and the deposition of mercury into surface water 

(from mercury that originated in the discharge of amalgam wastewater into sewerage treatment 

systems).. The available data on separator effectiveness reviewed in this Attachment indicates 

that (1) the amount of mercury in the influent and biosolids decrease after separators are installed 

(consistent with the principles of mass balance) and such a decrease should and usually is 

measurable1

, and (2) there is no observable decreases in the concentration of mercury in effluent 

following the installation of amalgam separators. 
4 

The purpose of the Clean Water Act and sewerage plants is to prevent releases to 

surface water. Regulatory action was not required until the Environmental Protection Agency 

(“EPA”) set the mercury water quality standard of 0.3 milligrams of mercury per kilogram of 

fish (“mg/kg” or “ppm”) and analytical techniques allowed measurements of nanogram per liter 

(“ng/L” or “ppt”) levels of mercury in effluent and it was found that fish in many areas contained 

mercury concentrations in excess of 0.3 ppm. Thus, the proper measure of amalgam separator 

“effectiveness” is the change, if any, in mercury concentrations in sewerage plant effluent (i.e., 

the discharge to the surface water in which the fish reside). As discussed below, the raw data on 

the impact of amalgam separators on the mercury concentration in sewerage treatment plant 

effluent is unclear and likely to small. 

IV. MILWAUKEE, WI

After working cooperatively with the Greater Milwaukee and Wisconsin Dental 

Associations and individual dentists to refine the elements of this program, the District adopted 

rules in January 2004 requiring the installation of amalgam separators.2 This was the first 

municipality in the Great Lakes region to require separators for amalgam.3

 

The municipality acknowledged that the sources being controlled (including 

dental offices) were “not the only cause for pollutant reductions. Other causes include: the 

movement of heavy manufacturing to areas with lower costs; the implementation of new, more 

efficient manufacturing processes; and the increasing amount of self-policing that is occurring as 

facilities implement environmental management systems.”4

 
5 

The Appendix to this Attachment contains the Milwaukee Metropolitan Sewerage 

District’s August 2007 analysis of its influent, biosolid, and effluent concentrations. Below are 

the relevant plots of the concentration of mercury in effluent versus time from this Appendix.5
6 

Figure 1: Milwaukee Metropolitan Sewerage District Mercury 

Concentration in Effluent 

Effluent Mercury

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)

Figure 2: Milwaukee Metropolitan Sewerage District Quarterly Average Mercury 

Concentration in Effluent 

Effluent Quarterly Averages

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Dec-03

Feb-04

Apr-04Jun-04

Aug-04

Oct-04

Dec-04

Feb-05

Apr-05Jun-05

Aug-05

Oct-05

Dec-05

Feb-06

Apr-06Jun-06

Aug-06

Oct-06

Dec-06

Feb-07

Apr-07Jun-07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)
7 

Figure 3: Milwaukee Metropolitan Sewerage District Mercury 

Concentration in Effluent with Alleged Outliers Removed 

Effluent Concentration with Outliers Removed

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)
8 

Figure 4: Milwaukee Metropolitan Sewerage District Mercury 

Mass in Effluent 

Jones Island Effluent Mass

0

1

2

3

4

5

6

7

8

9

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

grams/day

Figure 5: Milwaukee Metropolitan Sewerage District Mercury 

Mass in Effluent 

South Shore Effluent Mass

0

1

2

3

4

5

6

7

8

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

grams/day
9 

Both a visual observation of the data and the admittedly limited statistical tests 

performed on the data indicate that “[e]ffluent concentrations do not correlate with influent 

concentrations” and for both Jones Island and South Shore, “the trend line shows a slight 

increase in effluent concentration with decreasing influent concentration.”6 

V. WICHITA, KANSAS

The City of Wichita, Kansas initiated a phased program that resulted initially in 

60% of dental community voluntarily complying with the program.7 The program was 

implemented in October 2001. Presently, 99% of dentists have complied.8 

Figure 6: Wichita Loading and Date of Separator Implementation9

 
10 

Figure 7: Wichita Mercury Concentration in Effluent10

 

The data actually shows an increase in average mercury concentration from 2002 

(2.17 ng/L) to 2003 (2.77 ng/L) and that the largest decrease actually occurred from 2001 (3.57 

ng/L) to 2002 (2.17 ng/L) after requiring BMPs. 

Despite this cooperation from the local dental community, no clear pattern of a 

decrease in the mercury concentration in influent to or effluent from the treatment plant is 

discernible.11
11 

VI. DULUTH SEWERAGE TREATMENT PLANT

Separators in Duluth, Minnesota were installed from roughly June 1999 through 

December 2004. Although a pattern of a slight mercury decrease in sludge is discernible, no 

such pattern is clear in the treatment plant effluent. 

Figure 8: Duluth Mercury Concentration in Sludge and 

Date of Separator Installation12
12 

Figure 9: Duluth Mercury Concentration in Effluent13

VII. MADISON, WISCONSIN

As of 2005, 23 of the 103 dentists in Madison had installed separators.14 The 

regulatory goal was to have all general practice dentists install separators by December 31, 

2008.15 Table 1 (below) provides, among other things, the mercury concentration in the effluent 

from 2004 to 2006. 
13 

Table 1: Madison, Wisconsin Mercury Concentration in Effluent16

The 2004, 2005, and 2006 data show no trend yet, although it may be premature.17
14 

VIII. MINNEAPOLIS AREA

The Minneapolis Metropolitan Council on Environmental Services (“MCES”) 

launched its voluntary separator program in January 2003. 99% of general practice dental clinics 

in the Minneapolis area installed separators (724).18 The average concentration of mercury in the 

MCES Metro Plant effluent over time (through 9/5/07) is:19

1994: 11 ng/l 

2003: 8.4 

2004: 5.2 

2005: 5.0 

2006: 6.2 

2007: 3.1 

The ADA has not found information on the rate at which amalgam separators 

were installed in the MCES system. Additionally, there were strong efforts to implement best 

management amalgam waste handling practices and other mercury reduction/pollution 

prevention efforts prior to and after January 2003. This complicates interpretation of the data on 

average total mercury concentrations (particularly the decreases between 1994 and 2003 and 

between 2003 and 2004 and the further decrease from 2006 to the first part of 2007). 

Specifically, the decrease in 2007 through August strongly suggests that other mercury reduction 

efforts are at play given the likelihood that most of the separators have been installed for some 

time. Therefore, it is difficult to determine whether the changes in concentration are related 

primarily to the use of separators. 
15 

IX. PALO ALTO/BAY AREA

The Regional Water Quality Control Plant (“RWQCP”) covers dischargers 

located in Palo Alto, the East Palo Alto Sanitary District service area, Los Altos, and the town of 

Los Altos Hills. The due date for amalgam separator installation in this area was March 31, 

2005.20 By April 30, 2005, 96 percent of the 132 dental offices had certified that their amalgam 

separators were installed.21 Figure 10 below plots the mercury concentrations in the plant’s 

influent and effluent.

Figure 10: Palo Alto (i.e., Regional Water Quality Control Plant (RWQCP)) 

Mercury Concentration in Effluent22
16 

Figure 11: Palo Alto Mercury Concentration in Effluent 

Different Scale

Two things are immediately apparent from the Palo Alto data. First, the largest 

decrease in mercury effluent occurred from 1995 to 2000, prior to the installation of separators 

(see Figures 10 and 11). Second, given the scales of Figures 10 and Figure 11, little change is 

observable. Nevertheless, the raw data should be examined more carefully with appropriate 

statistical tools to better understand separator effectiveness in Palo Alto. 

X. EAST BAY MUNICIPAL UTILITY DISTRICT

In the East Bay Municipal Utility District (“EBMUD”), separators were installed 

between January 2004 and September 2005.23 More than 96% of permitted dental facilities have 

installed amalgam separators.24 Figure 12 shows the mercury concentrations in the influent and 

effluent from the plant. 

. 
17 
18 

Figure 12: EBMUD Comparison of Mercury Concentration in Influent and 

Effluent25

Given the scale, no increase or decrease can be observed, although there is no 

noticeable decrease. 

XI. OTHER SEWERAGE TREATMENT PLANTS

This brief review of the mercury concentration in effluent data available on line 

did not uncover other effluent data. In some cases (such as Narragansett Bay26), there are tables 

showing mercury concentration data for effluent for limited periods of time.27 In the case of 

Narragansett Bay, voluntary separators were installed from 2004 through the end of 2005, but the 

weekly mercury concentration in effluent data for 2005 suggests no downward trend. However, 

more information and a statistical analysis would be needed to reach a scientifically sound 

conclusion concerning the trends.. 
19 

XII. NACWA SEPARATOR EFFECTIVENESS STUDY

Samples of influent wastewater, treated effluent, and biosolids were collected and 

analyzed for total mercury concentrations, and some influent and effluent samples were analyzed 

for dissolved mercury concentrations. In addition, flow rates, total suspended solids, and 

turbidity were measured. 

The only publicly available summary of the study is a Power Point presentation 

that generally plots effluent mercury against the different sewerage treatment plants or the 

number of dental offices per million gallons of flow (i.e., this presentation did not plot the 

mercury concentrations in effluent before, during, and after installation of separators).28 

Although the ADA reviewed a written copy of the report, the ADA has not seen or reviewed the 

raw data. The ADA conclusions are as follows: 

First, the NACWA study adds significantly to the body of knowledge on the 

effectiveness of separators and collects the data in one location. 

Second, some of the treatment plants were implementing mercury reduction well 

before the NACWA study was initiated. As a result, we suspect that some of the data gathering 

may have limitations that might not exist in a prospective study. 

Third, the ADA is unable to determine when the separators were installed in the 

case of each treatment plant, making it difficult ascertain the true “effect” of the installations. In 

other words, an “effect” (i.e., a change in a treatment plant’s effluent mercury ), by definition, 

must be causally linked to the timing of the separator installations. 

Fourth, the draft report reviewed by the ADA did not take into account that some 

chemicals like sodium hypochlorite, which can have very high concentrations of mercury (e.g., 

Clorox® and Comet® can have microgram per kilogram levels of mercury), could be 

contributing significant amounts of mercury to treatment plant effluents. 
20 

Fifth, the trends in mercury concentration in effluent must be understood in the 

context of the overall mercury reduction programs implemented by the municipality. For 

example, most treatment plants that have historic data show a more dramatic decrease in the 

mercury concentration in influent, biosolids, and in effluent prior to the installation of separators. 

Both prior to and during the installation of separators, other significant mercury reduction 

program have been instituted nationwide. For example, the majority of dental offices that 

initially implemented the pre-2007 ADA Best Management Practices are contributing to 

significant reductions that are now intermingled with any reductions from the separators. Thus, 

any analysis of the impact of separators must take into account these other confounding factors. 

Sixth, the NACWA analysis includes attempts to correlate the number of dentists 

per million gallons of treatment plant flow. The information available on the plants is very 

limited. The data suggests that two of the twelve plants (treatment plants A and L) had higher 

concentrations of mercury in the effluent compared to the other plants. It is not discernible from 

the Power Point, whether any or all of this data was taken before, during or after separators were 

installed. Some figures suggest a higher mercury concentration with a increase in the number of 

dentists per million gallons of flow. However, the higher concentrations on these figures seem to 

be associated with treatment plant L and A, which were anomalous. 

Finally, this analysis is not based on accepted statistical methods (as far as can be 

determined from the publicly available information). More importantly, the mere existence of a 

high number of dentists per million gallons of flow does not fairly indicate a given dental 

community’s contribution to mercury in treatment plant effluent. Indeed, a number of dental 

offices in a community are highly correlated with high population and an urban setting. Thus, 

the mercury in the influent and effluent may be more a function of the larger number people, the 
21 

greater use of mercury-containing products, and a greater likelihood of industrial and other 

nondental commercial contribution. 

Finally, some of the samples were composites and others were grab samples, 

which may make comparisons more difficult. 

XIII. CONCLUSION

Although amalgam separators do increase the amount of amalgam that is 

recycled, the data does not demonstrate the effectiveness of amalgam separators in reducing the 

amount of mercury that is released to the environment. Aside from the lack of clear data on 

effluent effects, most of the data is from nonpeer reviewed reports and presentations, which is 

insufficiently robust to demonstrate whether mercury concentrations in sewerage treatment 

plants significantly decrease, increase or remain the same after the installation of amalgam 

separators in dental offices. The ADA urges EPA and/or NACWA to perform a more systematic 

statistical analysis of this data (and any other data that is available). 
#9134446 v2 

APPENDIX TO ATTACHMENT 2: 

MILWAUKEE METROPOLITAN SEWERAGE DISTRICT MERCURY 

DATA SUMMARY 
1 

Milwaukee Metropolitan Sewerage District 

Mercury Data Summary 

August 31, 2007 

Sample results show mixed outcomes, as shown in the following graphs. Influent and 

Milorganite show desirable results. At both Jones Island and South Shore, influent mercury 

concentrations and masses are decreasing. For both Jones Island and South Shore, a Kendall 

Trend Test identifies decreasing trends at a 95% confidence level. Milorganite concentrations 

are decreasing, but a Kendall Trend Test identifies a decreasing trend at only a 90% confidence 

level. In contrast, at both Jones Island and South Shore, effluent mercury concentrations and 

masses are increasing. Even when outliers are eliminated, the trend is increasing or stable. For 

the purpose of this analysis, outliers were defined as results more than two standard deviations 

from the average. Agri-Life concentrations are stable. 

Effluent concentrations show a correlation with flow and total suspended (TSS) concentrations. 

A possible explanation is that mercury performance is related to TSS performance and TSS 

removal tends to decrease as flows increase. In contrast, influent concentration does not 

correlate with flow. 

Effluent concentrations do not correlate with influent concentrations. For both Jones Island and 

South Shore, the trend line shows a slight increase in effluent concentration with decreasing 

influent concentration. 
2 

Influent Mercury

0

100

200

300

400

500

600

700

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

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11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)

Influent Quarterly Averages

0

50

100

150

200

250

300

350

400

450

Dec-03

Feb-04

Apr-04Jun-04

Aug-04

Oct-04

Dec-04

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Apr-05Jun-05

Aug-05

Oct-05

Dec-05

Feb-06

Apr-06Jun-06

Aug-06

Oct-06

Dec-06

Feb-07

Apr-07Jun-07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)
3 

Jones Island Influent Mass

0

20

40

60

80

100

120

140

160

180

9/17/03

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11/17/05

1/17/063/17/065/17/067/17/069/17/06

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1/17/073/17/075/17/07

grams/day

South Shore Influent Mass

0

50

100

150

200

250

300

350

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

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11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

grams/day
4 

Effluent Mercury

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)

Effluent Quarterly Averages

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Dec-03

Feb-04

Apr-04Jun-04

Aug-04

Oct-04

Dec-04

Feb-05

Apr-05Jun-05

Aug-05

Oct-05

Dec-05

Feb-06

Apr-06Jun-06

Aug-06

Oct-06

Dec-06

Feb-07

Apr-07Jun-07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)
5 

Effluent Concentration with Outliers Removed

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

11/17/04

1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

ng/L

Jones Island South Shore Linear (Jones Island) Linear (South Shore)

 
6 

Jones Island Effluent Mass

0

1

2

3

4

5

6

7

8

9

9/17/03

11/17/03

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11/17/05

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1/17/073/17/075/17/07

grams/day

South Shore Effluent Mass

0

1

2

3

4

5

6

7

8

9/17/03

11/17/03

1/17/043/17/045/17/047/17/049/17/04

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1/17/053/17/055/17/057/17/059/17/05

11/17/05

1/17/063/17/065/17/067/17/069/17/06

11/17/06

1/17/073/17/075/17/07

grams/day
7 

Jones Island Flow Versus Influent Concentration

0

50

100

150

200

250

300

0 100 200 300 400 500 600 700

Concentration (ng/L

Flow (MGD)

South Shore Flow Versus Influent Concentration

0

50

100

150

200

250

300

0 100 200 300 400 500 600 700

Concentration (ng/L)

Flow (MGD)
8 

Jones Island Flow Versus Effluent Concentration

0

50

100

150

200

250

300

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Concentration (ng/L)

Flow (MGD)

South Shore Flow Versus Effluent Concentration

0

50

100

150

200

250

300

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Concentration (ng/L)

Flow (MGD)
9 

Jones Island Effluent TSS and Mercury

0

2

4

6

8

10

12

14

16

18

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Mercury (ng/L)

TSS (mg/L)

South Shore Effluent TSS and Mercury

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Mercury (ng/L)

TSS (mg/L)
10 

Jones Island Influent Versus Effluent

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 100 200 300 400 500 600 700

Influent (ng/L)

Effluent (ng/L)

South Shore Influent Versus Effluent

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 100 200 300 400 500 600 700

Influent (ng/L)

Effluent (ng/L)
11 

Agri-Life Mercury Concentrations

0

0.5

1

1.5

2

2.5

3

9/8/03

11/8/03

1/8/043/8/045/8/047/8/049/8/04

11/8/04

1/8/053/8/055/8/057/8/059/8/05

11/8/05

1/8/063/8/065/8/067/8/069/8/06

11/8/06

1/8/073/8/075/8/07

mg/kg

Milorganite Mercury Concentrations

0

0.2

0.4

0.6

0.8

1

1.2

9/7/03

11/7/03

1/7/043/7/045/7/047/7/049/7/04

11/7/04

1/7/053/7/055/7/057/7/059/7/05

11/7/05

1/7/063/7/065/7/067/7/069/7/06

11/7/06

1/7/073/7/075/7/07

mg/kg
12 

ENDNOTES TO ATTACHMENT 2 TO THE ADA COMMENTS 

 

1

 There may be treatment plants where the concentration of mercury from other sources are so elevated that they 

may mask any reduction in mercury concentrations in influent or biosolids. 

2

 Milwaukee Metropolitan Sewer District, Source Reduction Effectiveness Analysis at 6 (May 2005), available at 

http://www.mmsd.com/docs/wastewatertreatment/05-067_Source_Red_Eff_Analysis_Report.pdf. 

3

 Milwaukee Metropolitan Sewer District, Source Reduction Effectiveness Analysis at 6 (May 2005), available at 

http://www.mmsd.com/docs/wastewatertreatment/05-067_Source_Red_Eff_Analysis_Report.pdf. 

. 

4

 Milwaukee Metropolitan Sewer District, Source Reduction Effectiveness Analysis at 6 (May 2005), available at 

http://www.mmsd.com/docs/wastewatertreatment/05-067_Source_Red_Eff_Analysis_Report.pdf.. 

5

 Milwaukee Metropolitan Sewerage District, Mercury Data Summary at 4 to 6 (August 31, 2007) (Appendix 1 to 

this Attachment). 

6

 Milwaukee Metropolitan Sewerage District, Mercury Data Summary at 2 (August 31, 2007) (Appendix 1 to this 

Attachment). 

7

 Wichita Silver and Mercury BMP Program, Jamie G. Belden, Pretreatment Specialist, Power Point Presentation, 

available <www.kansas.gov/uaa/sbcs/presentations/belden%20jamie%20p2%20case%20studies.pdf> at 12 of 34. 

8

 Wichita Silver and Mercury BMP Program, Jamie G. Belden, Pretreatment Specialist, Power Point Presentation, 

available <www.kansas.gov/uaa/sbcs/presentations/belden%20jamie%20p2%20case%20studies.pdf> at 12 of 34. 

9

 Wichita Silver and Mercury BMP Program, Jamie G. Belden, Pretreatment Specialist, Power Point Presentation, 

available <www.kansas.gov/uaa/sbcs/presentations/belden%20jamie%20p2%20case%20studies.pdf> at 18 of 34. 

10 Wichita Silver and Mercury BMP Program, Jamie G. Belden, Pretreatment Specialist, Power Point Presentation, 

available <www.kansas.gov/uaa/sbcs/presentations/belden%20jamie%20p2%20case%20studies.pdf> at 18 of 34. 

11 An Assessment of Mercury in the Form of Amalgam in Dental Wastewater in the United States. Jay A. Vandeven 

and Steve L. McGinnis, Water, Air, and Soil Pollution (2005) 164: 349–366, Springer 2005 (“2005 

Vandeven/McGinnis Article”). 

12 Mercury in Municipal Wastewater. Tim Tuominen, WLSSD, Rebecca Flood, MCES 

(September 19, 2007) available at <http://www.mnei.org/policy/images/HgTMDLmeetinginfo/WastewaterTreatment.pdf> at 16 of 35. 

13 Mercury in Municipal Wastewater. Tim Tuominen, WLSSD, Rebecca Flood, MCES 

(September 19, 2007) available at <http://www.mnei.org/policy/images/HgTMDLmeetinginfo/WastewaterTreatment.pdf> at 17 of 35. 

14 Madison Metropolitan Sewerage District, Mercury Pollutant Minimization Program at 4 (PMP), available at 

<http://www.madsewer.org/ProgramsAndInitiatives/Mercury/MercuryPMP.pdf>. 

15 Madison Metropolitan Sewerage District, Mercury Pollutant Minimization Program at 4 (PMP), available at 

<http://www.madsewer.org/ProgramsAndInitiatives/Mercury/MercuryPMP.pdf>). 

16 Madison Metropolitan Sewerage District, Mercury Pollutant Minimization Program at Appendix C (PMP). 

17 Madison Metropolitan Sewerage District, Mercury Pollutant Minimization Program at Appendix C (PMP) ), 

available at <http://www.madsewer.org/ProgramsAndInitiatives/Mercury/MercuryPMP.pdf>. 
13 

 

18 Mercury in Municipal Wastewater. Tim Tuominen, WLSSD, Rebecca Flood, MCES (September 19, 2007) 

available at <http://www.mn-ei.org/policy/images/HgTMDLmeetinginfo/WastewaterTreatment.pdf> at 27 of 35. 

19 Mercury in Municipal Wastewater. Tim Tuominen, WLSSD, Rebecca Flood, MCES (September 19, 2007) 

available at <http://www.mn-ei.org/policy/images/HgTMDLmeetinginfo/WastewaterTreatment.pdf> at 31 of 35. 

20 Clean Bay Pollution Prevention Plan 2007: The Pollution Prevention Plan for the City of Palo Alto's Regional 

Water Quality Control Plant at 35 (February 2007), available at <http://www.city.paloalto.ca.us/civica/filebank/blobdload.asp?BlobID=7149 >at 49 of 231. 

21 City of Palo Alto, Advanced Mercury Source Control Study, 2004 Annual Report of Activity at page 3 of 22 

(February 2005), available at <http://www.city.palo-alto.ca.us/civica/filebank/blobdload.asp?BlobID=3741>. 

22 Clean Bay Pollution Prevention Plan 2007: The Pollution Prevention Plan for the City of Palo Alto's Regional 

Water Quality Control Plant at 34 (February 2007), available at <http://www.city.paloalto.ca.us/civica/filebank/blobdload.asp?BlobID=7149 > (48 OF 231 of the pdf). 

23 EBMUD Wastewater Department, 2006 Pretreatment and Pollution Prevention Report at 3-18 (2006), , available 

at 

http://www.ebmud.com/wastewater/industrial_&_commercial_permits_&_fees/pollution_prevention_program/annu

al_report/ww_pollution_prevention_annualreport_2006.pdf (page 37 of 142 in the pdf) and BUD, Mercury Control 

at Dental Facilities – A Cost-Effective Model, NACWA 2006 National Pretreatment and Pollution Prevention 

Workshop at 16 of 18, available at <http://archive.nacwa.org/getfile.cfm?fn=2006pret-b.horenstein.ppt>. 

Unfortunately, the Power Point presentation does not illustrate the effluent data. 

24 EBMUD Wastewater Department, 2006 Pretreatment and Pollution Prevention Report at 6-7 (2006), available at 

<http://www.ebmud.com/wastewater/industrial_&_commercial_permits_&_fees/pollution_prevention_program/ann

ual_report/ww_pollution_prevention_annualreport_2006.pdf>. 

25 East Bay Municipal Utility District (“EBMUD”) Wastewater Department, 2006 Pretreatment and Pollution 

Prevention Report at 3-18 (2006), available at 

<http://www.ebmud.com/wastewater/industrial_&_commercial_permits_&_fees/pollution_prevention_program/ann

ual_report/ww_pollution_prevention_annualreport_2006.pdf>. 

26 Installation of separators resulted, according to the Narragansett Bay Commission resulted in 17% 

and 23% reductions in influent mercury at Field’s Point and Bucklin Point respectively. Narragansett Bay 

Commission, Protecting the Environment with Passion an d Integritty, ANNUAL REPORT | 2005 

 (2006), available at <http://www.narrabay.com/Documents/PDFs/NBC_Annual_Report_FY05.pdf>.

27Narragansett Bay Commission, Environmental Monitoring and Data Analysis, 2005 Monitoring Data at 40-42 and 

47-49 of 111 (October 2006), available at <http://www.narrabay.com/Documents/EMDA/Attachments%20All.pdf> 

at 42-44 and 49-51 of 111. 

28 Some of the preliminary results of the NACWA study were presented at the NACWA 2007 Pretreatment meeting. 

See Managing Mercury, Other Metals, and More, Elizabeth Toot-Levy – Moderator, Northeast Ohio Regional Sewer 

District, available at < http://www.nacwa.org/images/stories/public/07pret/2007pret-e.toot-levy.pdf >..