Meteorological and 

Hydrogen Cyanide 

(HCN) Fence Line 

Monitoring Report 

HOMESTAKE MINING 

COMPANY OF CALIFORNIA,

BARRICK RUBY HILL MINE

PROJECT 59-57-4 

JANUARY 2010 
Rubyhill-Hcn Monitoring Report_R1.Docx ii 

CONTENTS Page

1.0 INTRODUCTION ......................................................................................................................................................... 1

1.1 HCN Monitor Location ............................................................................................................................................ 1

1.2 HCN Monitoring System Description ...................................................................................................................... 5

1.3 Data Recovery ....................................................................................................................................................... 5

1.4 Quality Control ........................................................................................................................................................ 6

2.0 METEOROLOGY ....................................................................................................................................................... 7

2.1 Winds ..................................................................................................................................................................... 7

2.2 Temperature, Relative Humidity, and Barometric Pressure ............................................................................... 11

2.3 HCN Concentration .............................................................................................................................................. 12

3.0 DATA ANALYSIS ..................................................................................................................................................... 14

Tables 

Table 1: Sensor Locations ............................................................................................................................................... 5 

Table 2: Data Recovery ................................................................................................................................................... 6 

Table 3: Frequency of Hourly Averaged Winds by Direction and Speed ......................................................................... 8 

Table 4: Frequency of Hourly Averaged Winds by Direction and Stability ....................................................................... 9 

Table 5: Temperature, Relative Humidity, and Barometric Pressure ............................................................................. 11 

Table 6: HCN Concentration .......................................................................................................................................... 13 

Table 7: Measured HCN Concentration Analysis ........................................................................................................... 14 

Figures 

Figure 1: HCN Monitoring Site ......................................................................................................................................... 2 

Figure 2: Large Scale Area Map ...................................................................................................................................... 3 

Figure 3: Refinery ............................................................................................................................................................. 4 

Figure 4: Wind Frequency Distribution ........................................................................................................................... 10 

Figure 5: Measured HCN Concentration Analysis ......................................................................................................... 15 

Figure 6: Wind Frequency for January 8, 2010 (Highest Concentration Day) ............................................................... 16 

Figure 7: Wind Frequency for December 30, 2009 (Day with Highest Percent of Winds Blowing Towards Monitor) .... 16 

Appendices 

Appendix A: Hourly Meteorological Data

Appendix B: HCN Data

Appendix C: Site Check Forms, Audits, and Calibration

Appendix D: Hydrogen Cyanide (HCN) Fence Line Monitoring Plans 

 
Rubyhill-Hcn Monitoring Report_R1.Docx 1 

SECTION 1 

INTRODUCTION 

This report summarizes the meteorological and hydrogen cyanide (HCN) data collected at the 

Homestake Mining Company of California, Barrick Ruby Hill Mine (Ruby Hill) HCN monitor 

through January 11, 2010. The HCN monitor station became operational on December 7, 2009, at 1:00 

p.m. and the first 24-hour HCN sample was taken on December 9, 2009. The HCN monitoring 

equipment and sampling procedures followed Ruby Hill’s Site-Specific Hydrogen Cyanide (HCN) Fence 

Line Monitoring Plan, approved by EPA on November 25, 2009, and the general Hydrogen Cyanide 

(HCN) Fence Line Monitoring Plan, approved by EPA on October 9, 2009. The meteorological 

sampling procedures were performed in accordance with the U. S. EPA Quality Assurance Handbook of 

Air Pollution Measurement Systems Volume IV - Meteorological Measurements (EPA-600/R94-038D), 

March 1995. 

Ruby Hill operates a gold mining facility located 0.7 mile northwest of Eureka, Nevada on Highway 

50. The facility operates an open-pit mine. Gold recovery operations include: ore crushing, heap 

leaching, carbon adsorption, stripping and regeneration, electrowinning, retorting, and refining. The 

leach solutions used in the gold recovery processes contain cyanide. These solutions have the 

potential for low levels of hydrogen cyanide (HCN) formation and emission to the atmosphere. To 

assess the ambient concentrations of HCN, Ruby Hill installed and continues to operate an HCN 

monitor downwind of the potential HCN sources near the Ruby Hill operations area. 

1.1 HCN Monitor Location 

Aerial photos and shaded relief maps are provided in Figures 1 through 3. Figure 1 provides an 

aerial photo of the mine site, the operations boundary, the potential HCN sources, and the HCN 

monitor location. Figure 2 provides a shaded relief map of the area surrounding the Ruby Hill mine 

and shows the location of the HCN monitor. The HCN monitor is located at 588,792 meters east, 

4,375,085 meters north, UTM Zone 11N, NAD83, elevation 6,544 feet. 

Figures 1 and 3 highlight the potential sources of HCN emissions at Ruby Hill. These sources include 

an active leach pad, Carbon-in-Column (CIC) tanks, pregnant and barren ponds, a pregnant tank 

adjacent to the pregnant and barren ponds, a barren tank adjacent to the leach pad, and a single stack 

for the electrowinning cells and pregnant and barren tanks at the refinery. A closer view of the 

refinery area is shown in Figure 3. 
Rubyhill-Hcn Monitoring Report_R1.Docx 2
Rubyhill-Hcn Monitoring Report_R1.Docx 3
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1.2 HCN Monitoring System Description 

The HCN monitoring system consists of a data logger connected to a low-flow pump which is 

connected through sorbent tubes to an ambient air inlet. The sorbent tubes capture any HCN in the 

ambient air and are sent to the ALS Laboratory Group in Salt Lake City, Utah for analysis. The lab 

analysis is based on NIOSH Method 6010. The sampling schedule follows a 1-in-3 day calendar and 

will continue for a total sampling period of three months. 

During a run day, all meteorological parameters are collected at two-second intervals and timeaveraged into 15-minute values. Wind speed, wind direction, ambient temperature, relative 

humidity, and barometric pressure as well as flow rate through the sorbent tubes are collected at the 

HCN monitor. The parameters collected are shown in Table 1. 

The measurement height of the inlet is two meters. The height of the wind instruments is 10 meters. 

All other parameters are measured at two meters. 

Table 1: Sensor Locations 

(meters above the ground) 

Parameter Height 

Wind speed* 10.0 

Wind direction* 10.0 

Ambient temperature 2.0 

Relative humidity 2.0 

Barometric pressure 2.0 

Sampler Flow 2.0 

*Wind data from December 9, 2009, through January 6, 2010, were obtained from the Ruby Hill meteorological station (see 

Section 2.1). 

The meteorological data from the HCN monitor are recorded by the onsite digital Data Acquisition 

System (DAS) equipped with cellular internet for data transfer. The parameters are digitally 

processed by the DAS into 15-minute averages. The 15-minute averages are transmitted to Air 

Sciences for quality assurance checks, population into the database, and calculation of one-hour 

averages. 

1.3 Data Recovery 

Data recovery rates for all parameters are presented in Table 2. 

The meteorological data recovery rate was 91 percent or above for all parameters for this period, 

except for barometric pressure, which was 73 percent. The data recovery rate for the meteorological 

parameters was due to the site being shut down for maintenance and data logger program updates. 

The lower data recovery rate for the barometric pressure parameter was due to a data logger error, 

which was corrected on December 18, 2009. The data recovery rates at the meteorological station are 
Rubyhill-Hcn Monitoring Report_R1.Docx 6 

above the recommended rate of 90 percent for each meteorological parameter, except for the 

barometric pressure. 

The data recovery rate for the flow rate through the sorbent tubes was 91 percent. The data recovery 

rate for the HCN concentration from the sorbent tubes was 100 percent. Both parameters are above 

the recommended recovery rate of 75 percent. 

Table 2: Data Recovery 

December 9, 2009 - January 11, 2010 

(percent) 

 Recorded Recommended 

Parameter Observations Recovery Rate Recovery Rate 

HCN Station 

 Wind speed* 815 99.9 90 

 Wind direction* 815 99.9 90 

 Ambient temperature 262 91.0 90 

 Relative humidity 262 91.0 90 

 Barometric pressure 209 72.6 90 

 Flow 262 91.0 75 

 HCN concentration 12 100.0 75 

*The data recovery rate is for the combined data set from the HCN monitor and the Ruby Hill meteorological station. 

1.4 Quality Control 

The primary meteorological quality objectives are based on U.S. EPA guideline documents (EPA454/4-87-007, Section 6.1.1, Ambient Monitoring Guidelines for Prevention of Significant 

Deterioration [PSD] and EPA-454/R-99-005, February 2000, Table 5-1., Meteorological Monitoring 

Guidance for Regulatory Modeling Applications). The quality control objectives for the HCN 

monitor can be found in Appendix D. 

 
Rubyhill-Hcn Monitoring Report_R1.Docx 7 

SECTION 2 

METEOROLOGY 

The instantaneous wind speed, wind direction, temperature, relative humidity, and barometric 

pressure data collected at the station during the monitored period were processed into hourly 

averages. Wind speed and wind direction are reported for all days during the sample period. 

Temperature, relative humidity, and barometric pressure are reported for the run days during the 

period. Appendix A presents the hourly averages for each parameter in SAROAD (Storage and 

Retrieval of Aerometric Data) format. A summary of this data for each parameter is shown in the 

following sections. 

2.1 Winds 

The HCN monitor began collecting wind speed and wind direction data on January 6, 2010, at 11:00 

p.m. Hourly-averaged wind speed and wind direction data from December 9, 2009, through January 

6, 2010, was obtained from the monitoring station operated by Ruby Hill, which is collocated with the 

HCN monitor. These hourly averaged wind data were sent electronically to Air Sciences, where they 

were transferred into the database along with the data from the HCN monitor. The combined wind 

data set had a 99.9 percent data recovery rate. 

Hourly averaged winds measured at the site during the sampling period are summarized in Table 3 

as frequency distributions of winds by direction and speed. The data period contains approximately 

34 days (815 hours) of complete wind information. 

Figure 4 shows the distribution of hourly averaged winds by direction and speed for the sampling 

period. The mean wind speed for the period was 2.9 m/s (6.5 mph). The winds were predominately 

from the south-southeast to the south with a secondary peak from the west-northwest to the northnortheast. The winds ranged from moderate to brisk this period. A breakdown of the wind speed 

profile for this period yields the following: There were 8.2 percent calm wind speeds (<0.447 m/s), 

31.3 percent of the winds were between 0.5 m/s (1.1 mph) and 1.5 m/s (3.4 mph), 45.2 percent of the 

winds were between 1.5 m/s and 5 m/s (11.2 mph), and 15.2 percent of the wind speeds were greater 

than 5 m/s. 

Table 4 shows a frequency distribution of hourly averaged winds by direction and stability class. 

Stability classes A, B, and C indicate low-speed daytime winds, which are categorized as unstable or 

high-dispersion-potential winds with class A being the least stable. Stability classes E and F indicate 

the frequency of low-speed nighttime winds, which are categorized as stable or low-dispersionpotential winds with class E being the least stable. The D stability class is a mixture of daytime and 

nighttime winds, generally at higher speeds. This class is also referred to as neutral stability. 

The lower-speed daytime winds (classes A, B, and C) made up 29.2 percent of the total winds and 

were predominately from the northwest to the north-northeast with a secondary peak from the 
Rubyhill-Hcn Monitoring Report_R1.Docx 8 

south-southeast. The lower-speed nighttime winds (classes E and F) constituted 41.7 percent of the 

total winds and were predominately from the south-southeast to the south. The higher-speed winds 

(class D) comprised 27.2 percent of the total winds and were predominately from the south-southeast 

to the south. 

Table 3: Frequency of Hourly Averaged Winds by Direction and Speed 

December 9, 2009 - January 11, 2010 

(percent of occurrence) 

 Calm (< 0.447 m/s) = 8.2% 

 Mean wind speed = 2.9 m/s 

 Data presented as direction from which wind is blowing. 

Mean

Direction 0.5 <1.5 1.5 <3 3 <5 5 <7 7 <10 >=10 All Speed

N 3.7 1.2 0.9 0.7 0.0 0.0 6.5 2.1

NNE 3.9 0.9 0.3 0.0 0.0 0.0 5.1 1.3

NE 1.7 0.5 0.0 0.0 0.0 0.0 2.2 1.1

ENE 0.4 0.3 0.0 0.0 0.0 0.0 0.7 1.2

E 0.1 0.2 0.1 0.0 0.0 0.0 0.4 2.0

ESE 0.3 0.1 0.1 0.0 0.0 0.0 0.5 1.9

SE 0.9 0.4 0.2 0.5 0.6 0.0 2.6 3.9

SSE 3.1 9.5 11.6 4.2 6.1 0.6 35.1 4.4

S 2.5 3.7 2.2 1.3 0.8 0.0 10.6 3.2

SSW 1.0 1.1 0.2 0.1 0.0 0.0 2.4 2.0

SW 0.9 0.7 0.3 0.0 0.0 0.0 1.9 1.8

WSW 1.0 0.8 0.2 0.0 0.0 0.0 2.0 1.6

W 1.3 0.6 0.5 0.0 0.0 0.0 2.4 1.9

WNW 2.7 1.7 0.5 0.0 0.0 0.0 4.9 1.5

NW 4.5 3.3 0.1 0.0 0.0 0.0 7.9 1.5

NNW 3.1 1.9 1.0 0.3 0.0 0.0 6.3 2.0

All 31.3 27.0 18.2 7.1 7.5 0.6 91.8 2.9

Speed Class Intervals (m/s)
Rubyhill-Hcn Monitoring Report_R1.Docx 9 

Direction A B C D E F All

N 1.4 1.8 0.9 1.4 0.8 0.8 7.1

NNE 1.4 0.8 1.8 0.9 0.5 0.4 5.8

NE 0.4 0.8 0.3 0.3 0.1 0.6 2.5

ENE 0.2 0.3 0.2 0.0 0.0 0.2 0.9

E 0.3 0.2 0.0 0.1 0.0 0.4 1.0

ESE 0.1 0.3 0.0 0.0 0.0 0.3 0.7

SE 0.2 0.4 0.3 0.8 0.2 1.0 2.9

SSE 0.3 1.5 2.2 15.6 13.2 2.8 35.6

S 0.4 0.6 1.0 3.6 2.8 2.8 11.3

SSW 0.4 0.3 0.1 0.5 0.5 1.1 2.9

SW 0.0 0.0 0.1 0.3 0.7 0.6 1.7

WSW 0.4 0.1 0.0 0.4 0.5 0.9 2.3

W 0.1 0.1 0.6 0.2 0.6 0.9 2.5

WNW 0.4 0.7 0.4 0.9 1.3 1.8 5.5

NW 0.8 1.5 1.3 1.0 1.6 1.8 8.0

NNW 0.8 1.0 1.8 1.1 1.1 1.3 7.1

All 7.6 10.5 11.1 27.2 23.9 17.8 98.1

Stability Class

Table 4: Frequency of Hourly Averaged Winds by Direction and Stability 

December 9, 2009 - January 11, 2010 

(percent of occurrence) 
Rubyhill-Hcn Monitoring Report_R1.Docx 10 

Figure 4: Wind Frequency Distribution 

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

0.5 1 5 8 10 m/s

Hourly Met Data

Wind Frequency Distribution: 12/09/09 - 01/11/10

Calm = 78 Missing = 0

Number of non-calm/missing = 739
Rubyhill-Hcn Monitoring Report_R1.Docx 11 

2.2 Temperature, Relative Humidity, and Barometric Pressure 

The temperature mean and extremes for the sampling period are presented in Table 5. The average 

2-meter temperature for the period was -3.42°C (25.84°F). The maximum hourly averaged 2-meter 

temperature was 5.61°C (42.10°F) and occurred on the afternoon of January 5, 2010. The minimum 

hourly averaged 2-meter temperature was -12.07°C (10.27°F) and occurred on the morning of 

December 24, 2009. 

The relative humidity mean and extremes for the sampling period are presented in Table 5. The 

average relative humidity for the period was 66 percent. The minimum hourly average was 27 

percent and the maximum was 97 percent. 

Barometric pressure data collected during the sampling period (beginning December 18, 2009) are 

summarized in Table 5. The average barometric pressure for the period was 602 mmHg. The 

maximum hourly averaged barometric pressure for the period was 606 mmHg and occurred for nine 

hours in the morning of January 11, 2010. The minimum hourly averaged barometric pressure for the 

period was 592 mmHg and occurred for one hour in the evening of December 21, 2009. 

Table 5: Temperature, Relative Humidity, and Barometric Pressure 

December 9, 2009 - January 11, 2010 

Parameter 

Temperature 

(°C)

Relative 

Humidity 

(%) 

Barometric 

Pressure 

(mmHg) 

Avg. -3.42 66 602 

Max. 5.61 97 606 

Min. -12.07 27 592 
Rubyhill-Hcn Monitoring Report_R1.Docx 12 

2.3 HCN Concentration 

As mentioned in Section 1.3 above, the barometric pressure began recording on December 18, 2009. 

For the first three run days (December 9, 12, and 15, 2009) the standard barometric pressure at the site 

elevation (597 mmHg) was used to calculate the HCN concentration from the mass of HCN collected. 

As shown in Table 5, the average barometric pressure from the data collected (602 mmHg) was 

within 5 mmHg of the standard pressure. 

The HCN monitor was designed with three sorbent tubes so that a site visit to change the tubes is 

only required every nine days. After the first three run days, the sorbent tubes were not replaced and 

each tube was sampled for an additional 24-hour period. Therefore, December 9 and 18, were 

sampled on the same sorbent tube; December 12 and 21, were sampled on the same sorbent tube; and 

December 15 and 24, 2009, were sampled on the same sorbent tube. Although attributing the HCN 

contribution from one tube to a single run day is not possible, all of the tubes were below the 

detection level of 0.21 μg/sample and, therefore, the HCN concentration for each day is below the 

detection level. 

The HCN concentration data collected during the sampling period are summarized in Table 6. For all 

of the run days, except January 8, 2010, the HCN concentration was below the detection level of 0.21 

μg/sample. On January 8, 2010, the HCN concentration was 0.16 μg/m3. Using the detection level 

mass of HCN and the sample flow rate, the HCN concentration for all of the non-detect days was 

estimated. Based on the sample flow rates and the detection level, it is possible for non-detect days 

show to a higher HCN concentration than the only day that had a detectable amount of HCN; 

however, the actual HCN concentration for the non-detect days is below the calculated amount. The 

HCN concentration in the field blank was below the detection level of 0.21 μg/sample. All HCN 

concentrations were below the EPA reference concentration of 3 μg/m3. 
Rubyhill-Hcn Monitoring Report_R1.Docx 13 

Table 6: HCN Concentration 

December 9, 2009 - January 11, 2010 

(μg/m3

) 

 HCN Concentration 

Run Day* 

Actual 

Conditions 

Standard 

 Conditions1

12/09/2009 <0.07 <0.08 

12/12/2009 <0.06 <0.07 

12/15/2009 <0.07 <0.07 

12/18/2009 <0.07 <0.08 

12/21/2009 <0.06 <0.07 

12/24/2009 <0.07 <0.07 

12/27/2009 <0.11 <0.12 

12/30/2009 <0.11 <0.13 

01/02/2010 <0.12 <0.14 

01/05/2010 <0.15 <0.17 

01/08/2010 0.14 0.16 

01/11/2010 <0.11 <0.12 

Average <0.10 <0.11 

*Start time = 0:00:02; stop time = 0:00:00. 

 

1 Standard conditions are 1 atmosphere and 25°C. 
Rubyhill-Hcn Monitoring Report_R1.Docx 14 

SECTION 3 

DATA ANALYSIS 

Based on the data collected from the first four weeks of monitoring, an analysis of wind direction and 

measured HCN concentration was conducted. As shown in Figures 1 and 2, winds from 302°

through 311° (approximately west-northwest through northwest) blew from the potential HCN 

sources at the Ruby Hill mine towards to the HCN monitor. The percent of winds blowing within 

this range of directions on each sample day is shown in Table 7 and Figure 5. 

As shown by Table 7 and Figure 5, there does not appear to be a correlation between wind direction 

and measured HCN concentration. On the only day with HCN above the detection level, the winds 

blew from the potential HCN sources towards the monitor only four percent of the time. On the day 

with the highest percent of winds (13 percent) blowing from the potential HCN sources towards the 

monitor, the HCN concentration was below detection level. 

Table 7 also shows that there does not appear to be a correlation between wind speed and measured 

HCN concentration. The days with the highest and lowest average wind speed both showed HCN 

concentrations below the detection level. 

Table 7: Measured HCN Concentration Analysis 

December 9, 2009 - January 11, 2010 

HCN 

Concentration 

Winds Blowing from HCN 

Sources Towards Monitor 

Average Wind 

Speed 

Run Day (μg/m3) No. of Hours Percent (m/s) 

12/09/2009 <0.08 0 0 2.1 

12/12/2009 <0.07 0 0 8.3 

12/15/2009 <0.07 0 0 7.2 

12/18/2009 <0.08 2 8 2.4 

12/21/2009 <0.07 2 8 5.1 

12/24/2009 <0.07 0 0 1.3 

12/27/2009 <0.12 0 0 1.6 

12/30/2009 <0.13 3 13 1.9 

01/02/2010 <0.14 0 0 2.6 

01/05/2010 <0.17 0 0 2.1 

01/08/2010 0.16 1 4 1.2 

01/11/2010 <0.12 1 4 4.0 

Average <0.11 
Rubyhill-Hcn Monitoring Report_R1.Docx 15 

Figure 5: Measured HCN Concentration Analysis 

Figures 6 and 7 summarize the 24-hour wind direction (the direction from which the wind is 

blowing) and wind speed for the only day with the HCN concentration above the detection level, and 

the day with the highest percent of winds blowing from the potential HCN sources towards the 

monitor. The above-detection level HCN concentration was measured on January 8, 2010, when the 

winds were predominantly from the south-southeast and north. The day with the highest percent of 

winds blowing towards the monitor was on December 30, 2009, when 13 percent of winds blew from 

the potential HCN sources towards the HCN monitor.

0

2

4

6

8

10

12

14

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

Percent of Winds (%)

HCN Concentration (μg/m3)

Run Day

HCN Concentration Percentof Winds Towards Monitor
Rubyhill-Hcn Monitoring Report_R1.Docx 16 

3%

6%

9%

12%

15%

18%

21%

24%

27%

30%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

0.5 1 5 8 10 m/s

Hourly Met Data

Wind Frequency Distribution: 12/30/2009

Calm = 1 Missing = 0

Number of non-calm/missing = 23

4%

8%

12%

16%

20%

24%

28%

32%

36%

40%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

0.5 1 5 8 10 m/s

Hourly Met Data

Wind Frequency Distribution: 1/8/2010

Calm = 3 Missing = 0

Number of non-calm/missing = 21

Figure 6: Wind Frequency for January 8, 2010 (Highest Concentration Day) 

Figure 7: Wind Frequency for December 30, 2009 (Day with Highest Percent of Winds Blowing 

Towards Monitor) 
 

APPENDIX A 

Hourly Meteorological Data 
Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

12/9/2009 1.1 1.4 1.8 1.4 1.0 0.7 0.9 0.7 0.2 1.2 1.8 1.3 1.4 0.9 0.5 0.4 2.2 4.7 4.8 5.7 5.5 5.3 

12/10/2009 2.2 2.5 0.9 1.5 3.0 3.7 1.7 0.7 0.1 0.3 0.6 0.8 0.6 0.1 0.3 0.9 3.3 5.8 5.7 4.9 5.1 2.4 12/11/2009 1.1 0.9 1.1 0.4 0.5 0.2 0.3 0.7 4.1 5.9 7.4 8.8 9.2 8.5 8.1 8.1 6.4 7.1 6.7 5.0 4.8 5.6 12/12/2009 9.5 9.7 10.5 9.4 10.0 10.2 10.2 9.2 9.0 8.3 8.8 9.6 8.8 7.8 9.5 8.2 7.9 5.0 6.7 4.6 5.6 7.9 12/13/2009 1.5 0.5 0.5 1.3 0.9 1.8 1.9 2.1 0.8 3.8 2.9 4.6 4.9 4.6 4.2 2.3 0.7 0.7 1.0 0.2 1.6 0.9 12/14/2009 2.2 1.8 2.3 0.6 2.4 2.3 2.5 2.8 1.2 0.8 2.1 1.3 0.6 1.2 1.1 1.5 4.7 5.8 6.7 6.7 6.5 4.3 12/15/2009 8.3 10.7 8.1 7.1 8.1 8.7 7.8 8.2 7.5 7.1 8.3 7.4 6.0 6.1 7.0 7.3 6.4 7.0 5.0 0.6 3.8 9.0 12/16/2009 4.1 1.2 2.4 2.4 1.0 4.3 6.3 2.2 1.7 1.1 0.7 0.9 1.2 0.6 1.1 0.7 2.9 3.2 4.1 4.8 4.9 3.7 12/17/2009 3.5 4.0 3.0 3.2 4.4 2.7 2.8 1.9 0.0 0.4 1.1 0.7 0.8 1.8 0.4 0.6 1.5 1.4 2.0 3.0 3.8 3.9 12/18/2009 2.3 4.3 4.9 2.4 2.8 2.0 3.0 1.5 0.6 1.0 0.6 1.1 1.3 0.7 1.5 1.0 0.9 2.8 4.1 3.9 4.4 3.8 12/19/2009 4.1 5.2 5.1 3.8 2.2 4.3 4.9 4.1 0.9 0.6 1.0 0.5 1.0 0.7 0.9 0.4 1.7 1.3 0.0 0.3 1.6 2.8 12/20/2009 0.3 0.6 0.8 1.0 1.1 0.5 0.3 1.2 1.1 1.3 2.5 1.7 2.2 1.5 6.2 5.3 4.1 5.2 5.5 5.4 6.5 1.8 12/21/2009 2.7 2.1 2.3 1.0 2.8 5.9 8.2 4.5 2.2 5.1 2.2 1.7 1.9 4.3 6.8 5.5 6.0 7.7 7.5 9.7 10.4 9.4 12/22/2009 4.4 1.1 0.7 0.6 1.9 1.7 1.4 1.5 2.9 5.9 5.3 6.7 6.4 5.6 5.5 4.5 3.3 3.8 2.7 2.7 2.4 2.7 12/23/2009 1.9 1.8 1.9 2.1 2.5 2.4 1.6 1.6 1.2 2.1 1.6 1.8 2.1 2.1 1.9 2.0 2.1 1.7 1.7 2.0 1.7 1.6 12/24/2009 1.4 1.8 0.8 0.2 0.5 0.1 0.4 2.0 0.5 0.7 0.5 0.9 1.9 0.8 0.9 0.3 2.0 2.6 3.1 3.1 3.0 2.0 12/25/2009 2.2 2.6 0.8 0.0 0.8 1.2 1.0 2.2 0.7 0.6 1.1 1.0 1.0 1.3 1.8 2.0 1.1 0.3 1.8 3.8 4.3 4.7 12/26/2009 5.0 4.2 2.9 0.9 1.5 0.6 0.8 2.3 1.2 2.3 3.6 4.4 1.9 6.9 7.8 6.1 3.5 2.3 5.4 3.3 4.9 3.1 12/27/2009 0.9 0.1 2.2 3.2 2.8 2.6 1.9 0.3 1.4 0.7 1.3 1.1 1.1 1.3 0.5 0.2 1.1 2.6 3.6 2.8 0.4 2.9 12/28/2009 0.4 0.8 0.5 0.8 0.7 0.5 0.8 2.0 0.4 1.1 1.5 1.4 1.4 1.5 1.6 3.1 4.6 2.9 0.9 2.3 4.1 3.6 12/29/2009 1.8 1.7 2.8 0.8 0.2 0.1 0.0 0.0 0.0 0.6 1.0 1.0 1.9 1.3 1.6 1.4 0.5 2.8 3.0 3.9 3.4 1.4 12/30/2009 3.0 2.4 1.6 1.0 0.1 2.2 1.1 0.5 3.1 1.7 2.5 4.0 3.6 2.9 0.9 0.9 2.0 0.7 0.7 0.7 1.1 0.7 12/31/2009 5.0 4.7 4.4 4.4 5.9 5.8 5.5 2.8 1.8 1.9 1.9 1.2 0.5 1.2 5.1 8.3 3.9 7.8 3.6 4.2 0.7 3.2 

1/1/2010 2.4 2.3 2.3 3.4 0.8 0.5 0.9 1.2 5.2 2.1 1.2 1.0 1.0 0.1 0.3 1.6 2.5 4.3 3.4 2.9 1.8 1.6 1/2/2010 4.7 4.8 2.3 1.1 1.0 1.6 3.4 3.9 2.0 1.4 0.4 1.2 0.9 1.5 0.2 0.1 1.5 4.0 4.7 4.4 4.0 5.4 1/3/2010 4.2 4.8 2.8 3.8 4.4 2.5 2.4 1.8 0.6 0.1 1.0 0.8 0.7 0.8 0.3 0.2 0.0 0.1 0.5 1.0 0.7 0.2 1/4/2010 0.2 0.1 0.9 0.2 0.1 0.0 0.0 0.4 0.2 0.8 0.6 0.6 0.9 0.7 0.4 0.4 2.9 2.3 5.1 5.8 4.9 2.8 1/5/2010 2.2 5.7 5.2 1.1 4.0 5.4 3.1 1.6 0.6 1.8 1.1 0.6 1.0 0.2 0.0 0.2 2.0 2.7 1.6 0.1 1.8 1.2 1/6/2010 2.7 2.0 2.5 3.0 3.8 4.2 3.8 3.0 0.8 0.4 0.9 1.1 1.3 1.5 1.1 0.2 0.8 1.8 2.7 1.1 0.4 0.4 1/7/2010 0.5 0.4 0.4 0.6 0.5 0.6 0.7 0.8 0.7 1.1 1.0 1.0 0.9 0.9 0.5 1.1 1.9 1.5 1.8 2.1 2.1 2.4 1/8/2010 3.3 3.7 3.2 1.0 0.4 0.3 0.7 0.8 0.8 0.8 0.7 0.9 0.7 0.9 0.6 0.4 1.0 0.5 1.3 2.0 1.2 0.9 1/9/2010 0.6 0.6 2.1 2.1 1.8 1.5 3.4 1.7 0.5 0.5 0.7 0.7 0.4 0.5 0.5 0.8 2.0 1.2 0.6 0.5 1.1 0.7 

1/10/2010 0.6 1.2 2.2 1.6 1.0 1.7 1.1 0.5 0.4 0.8 1.0 0.8 0.5 0.4 0.5 0.6 1.7 1.3 1.6 2.2 2.0 1.5 1/11/2010 2.3 3.0 3.7 3.0 2.2 1.2 0.8 0.7 2.0 1.0 1.3 0.7 3.5 5.4 4.2 4.9 6.0 7.2 8.2 7.8 8.0 9.4 

Avg 2.7 2.8 2.6 2.1 2.3 2.5 2.5 2.1 1.7 1.9 2.1 2.2 2.2 2.3 2.5 2.4 2.8 3.3 3.5 3.3 3.5 3.3 

Max 9.5 10.7 10.5 9.4 10.0 10.2 10.2 9.2 9.0 8.3 8.8 9.6 9.2 8.5 9.5 8.3 7.9 7.8 8.2 9.7 10.4 9.4 

Min 0.2 0.1 0.4 0.0 0.1 0.0 0.0 0.0 0.0 0.1 0.4 0.5 0.4 0.1 0.0 0.1 0.0 0.1 0.0 0.1 0.4 0.2 

‐‐ Indicate invalid dataWind data from December 9, 2009, through January 6, 2010, were obtained from the Ruby Hill meteorological station.

SAROAD for Barrick, RubyHill

Channel: WS_ms_10m

Month: 12/09/09 ‐ 01/11/10

Hour of da

y
Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 

12/9/2009 242 209 241 232 177 202 175 157 173 37 47 31 3 17 322 27 166 166 165 164 166 

12/10/2009 169 155 185 157 158 163 170 167 174 45 354 17 28 26 30 155 162 166 165 163 164 12/11/2009 149 293 313 283 312 294 357 300 164 158 153 150 142 148 151 158 156 164 161 152 152 12/12/2009 160 159 156 156 156 160 158 159 156 155 157 152 151 147 157 148 143 138 175 156 169 12/13/2009 309 53 327 360 245 258 228 238 27 274 302 273 261 275 283 286 301 277 0 90 155 12/14/2009 192 200 259 68 163 170 165 170 299 27 37 46 354 66 79 123 168 169 167 165 171 12/15/2009 158 159 172 168 156 157 157 156 156 160 163 165 156 160 166 164 159 167 184 43 143 12/16/2009 219 275 235 177 197 158 172 222 288 324 7 24 333 324 295 357 165 158 163 165 165 12/17/2009 165 165 162 160 169 178 160 165 250 342 340 7 17 329 343 314 157 170 153 165 168 12/18/2009 171 165 164 166 161 155 163 163 132 337 22 4 348 330 307 306 163 165 168 166 165 12/19/2009 165 165 166 171 156 163 168 165 308 30 311 15 324 27 0 307 187 145 235 123 163 12/20/2009 167 300 229 27 304 140 135 297 359 353 319 309 314 226 158 175 171 182 176 177 173 12/21/2009 191 135 193 187 151 162 162 159 315 138 303 312 311 141 158 162 155 156 156 152 152 12/22/2009 156 349 322 157 310 12 281 303 303 352 360 2 355 329 336 330 327 347 328 323 313 12/23/2009 325 327 330 329 306 308 314 318 314 313 331 7 359 334 337 304 310 304 293 286 290 12/24/2009 273 273 311 342 283 333 197 171 221 346 24 24 38 24 348 354 161 163 164 167 164 12/25/2009 165 163 155 152 157 155 166 162 172 23 27 335 351 340 20 0 277 194 164 165 167 12/26/2009 167 165 166 169 160 265 293 152 133 121 204 166 326 150 159 168 178 199 178 189 183 12/27/2009 296 290 166 161 171 141 175 203 141 5 346 11 329 1 41 134 157 167 178 213 224 12/28/2009 169 275 271 301 249 282 170 193 328 346 320 340 4 2 1 176 164 177 335 166 147 12/29/2009 233 152 185 335 321 309 0 0 0 8 35 326 313 308 320 318 287 166 167 169 179 

12/30/2009 191 284 257 282 197 169 187 243 299 326 321 309 340 333 310 340 347 351 208 175 307 12/31/2009 166 162 166 165 164 164 184 196 271 5 349 330 309 1 130 160 116 169 97 202 24 

1/1/2010 190 177 133 185 268 293 73 148 165 204 345 102 248 43 183 154 173 165 188 168 165 1/2/2010 167 167 164 169 176 162 166 166 173 312 39 19 60 67 72 207 163 165 165 166 167 1/3/2010 167 177 170 168 164 154 169 152 174 326 17 40 42 29 27 331 210 295 302 337 319 1/4/2010 1 148 311 76 25 285 80 111 17 27 3 15 17 360 35 4 164 152 164 163 159 1/5/2010 184 162 167 159 162 164 174 216 172 150 348 335 29 81 145 57 204 160 167 244 158 1/6/2010 167 173 170 161 164 166 167 163 151 353 13 25 19 311 322 188 44 175 167 164 295 1/7/2010 358 300 261 321 335 48 49 310 338 309 356 3 8 17 359 174 150 161 168 163 153 1/8/2010 154 156 154 156 41 116 143 325 353 3 8 7 5 240 244 95 309 161 131 179 216 

1/9/2010 313 244 173 179 161 137 154 92 2 21 16 14 83 296 16 279 165 158 193 188 167 

1/10/2010 125 181 157 181 169 171 304 161 82 3 348 17 45 31 3 51 172 170 155 161 156 1/11/2010 157 160 153 165 167 248 116 141 309 327 312 340 215 141 148 161 150 145 142 134 147 

Max 358 349 330 360 335 333 357 325 359 353 360 340 359 360 359 357 347 351 335 337 319 

Min 1 53 133 27 25 12 0 0 0 3 3 2 3 1 0 0 44 138 0 43 24 

‐‐ Indicate invalid dataWind data from December 9, 2009, through January 6, 2010, were obtained from the Ruby Hill meteorological station.

SAROAD for Barrick, RubyHill

Channel: WD_10m

Month: 12/09/09 ‐ 01/11/10

Hour of da

y
Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

12/9/2009 ‐15.83 ‐16.10 ‐15.69 ‐16.72 ‐16.91 ‐16.49 ‐16.11 ‐15.97 ‐12.78 ‐8.58 ‐7.34 ‐6.07 ‐6.00 ‐5.30 ‐5.22 ‐6.35 ‐10.03 ‐13.36 ‐14.26 ‐14.00 ‐13.93 ‐13.7

12/10/200912/11/200912/12/2009 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐3.08 ‐2.84 ‐2.4

12/13/200912/14/200912/15/2009 ‐2.93 ‐2.81 ‐2.83 ‐2.91 ‐2.49 ‐2.56 ‐2.48 ‐2.22 ‐1.81 ‐1.34 ‐0.75 ‐0.57 ‐0.27 ‐0.30 ‐0.59 ‐0.20 ‐0.08 ‐0.08 ‐0.35 ‐2.23 ‐1.39 0.32 

12/16/200912/17/200912/18/2009 ‐‐ ‐‐ ‐3.07 ‐3.27 ‐4.60 ‐4.65 ‐3.66 ‐3.06 0.01 2.33 2.87 4.16 4.68 4.98 4.47 3.26 1.20 ‐2.17 ‐2.95 ‐3.31 ‐3.96 ‐4.2

12/19/200912/20/200912/21/2009 ‐2.13 ‐2.46 ‐3.30 ‐3.36 ‐4.74 ‐2.30 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐0.63 ‐0.62 1.34 0.93 0.28 ‐0.19 ‐0.42 ‐0.71 ‐0.91 ‐1.28 ‐1.8

12/22/200912/23/200912/24/2009 ‐11.17 ‐10.65 ‐10.87 ‐11.50 ‐11.45 ‐11.71 ‐12.07 ‐11.69 ‐8.55 ‐5.03 ‐3.87 ‐2.73 ‐2.89 ‐2.22 ‐2.26 ‐3.75 ‐7.20 ‐10.25 ‐10.59 ‐10.46 ‐10.39 ‐9.9

12/25/200912/26/200912/27/2009 ‐8.83 ‐9.24 ‐9.24 ‐7.54 ‐8.08 ‐8.59 ‐8.93 ‐9.96 ‐8.06 ‐3.12 ‐3.14 ‐1.35 ‐2.04 ‐1.43 ‐0.42 ‐2.93 ‐4.60 ‐5.41 ‐6.10 ‐7.42 ‐8.47 ‐8.6

12/28/200912/29/200912/30/2009 ‐5.11 ‐5.23 ‐5.52 ‐5.84 ‐5.78 ‐5.94 ‐5.97 ‐5.40 ‐4.53 ‐4.40 ‐4.08 ‐4.84 ‐4.75 ‐5.13 ‐5.16 ‐4.98 ‐5.65 ‐6.28 ‐7.28 ‐7.59 ‐8.01 ‐8.1

12/31/2009

1/1/20101/2/2010 ‐3.77 ‐3.71 ‐3.34 ‐2.85 ‐3.90 ‐3.97 ‐4.46 ‐5.24 ‐3.02 1.22 3.96 4.06 4.93 4.18 3.69 2.19 ‐0.33 ‐2.84 ‐4.24 ‐4.70 ‐5.81 ‐4.8

1/3/20101/4/20101/5/2010 ‐4.89 ‐5.21 ‐3.48 ‐4.27 ‐5.61 ‐4.09 ‐3.36 ‐4.10 ‐3.96 0.24 2.30 1.97 3.29 5.61 5.12 4.24 2.19 0.72 0.52 0.45 0.33 0.11 

1/6/20101/7/20101/8/2010 ‐9.44 ‐9.50 ‐8.69 ‐8.87 ‐7.96 ‐9.46 ‐11.51 ‐11.81 ‐10.37 ‐8.71 ‐6.45 ‐4.82 ‐4.28 ‐3.31 ‐2.81 ‐2.59 ‐2.84 ‐3.16 ‐3.41 ‐1.39 ‐1.43 ‐2.4

1/9/2010

1/10/20101/11/2010 ‐2.95 ‐3.53 ‐3.02 ‐2.97 ‐2.40 ‐2.75 ‐3.47 ‐4.05 ‐0.44 1.56 2.66 2.46 2.76 3.29 3.93 3.44 2.26 1.73 2.37 2.99 3.04 2.32 

Avg ‐6.04 ‐6.19 ‐5.61 ‐5.61 ‐6.06 ‐5.94 ‐6.68 ‐6.91 ‐4.86 ‐1.99 ‐0.72 ‐0.19 0.12 0.81 0.83 ‐0.09 ‐1.69 ‐3.12 ‐3.60 ‐3.59 ‐4.00 ‐4.1

Max ‐2.13 ‐2.46 ‐3.02 ‐2.85 ‐2.40 ‐2.30 ‐3.36 ‐3.06 0.01 2.33 3.96 4.16 4.93 5.61 5.12 4.24 2.26 1.73 2.37 2.99 3.04 2.32 

Min ‐11.17 ‐10.65 ‐10.87 ‐11.50 ‐11.45 ‐11.71 ‐12.07 ‐11.81 ‐10.37 ‐8.71 ‐6.45 ‐4.84 ‐4.75 ‐5.13 ‐5.16 ‐4.98 ‐7.20 ‐10.25 ‐10.59 ‐10.46 ‐10.39 ‐9.9

‐‐ Indicate invalid data

SAROAD for Barrick, RubyHill

Channel: T_AMB_C

Month: 12/09/09 ‐ 01/11/10

Hour of da

y

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day

Non‐Run‐Day
Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

12/9/2009 64 63 61 68 68 71 71 72 61 47 43 37 40 37 32 36 50 61 63 61 60 58 

12/10/200912/11/200912/12/2009 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ 93 93 88 

12/13/200912/14/200912/15/2009 66 68 69 68 68 72 73 72 68 66 62 63 60 61 63 59 56 57 55 69 64 50 12/16/200912/17/200912/18/2009 ‐‐ ‐‐ 77 77 78 80 80 79 65 57 57 53 51 49 50 55 62 74 77 78 78 79 12/19/200912/20/200912/21/2009 60 63 64 63 68 62 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ 59 58 52 54 57 59 60 62 63 65 68 

12/22/200912/23/200912/24/2009 81 78 77 80 79 78 78 75 63 55 52 41 44 45 43 48 57 66 66 65 64 61 12/25/200912/26/200912/27/2009 71 71 69 61 63 64 65 72 63 45 49 45 48 46 42 51 59 59 58 63 72 64 12/28/200912/29/200912/30/2009 87 89 93 97 97 96 97 97 95 96 95 96 95 95 95 95 96 95 95 93 93 92 12/31/2009

1/1/20101/2/2010 73 73 71 65 71 72 71 73 66 55 49 50 45 43 42 47 54 61 60 57 58 52 1/3/20101/4/20101/5/2010 54 55 46 46 51 46 45 49 52 40 38 37 37 30 27 31 37 46 49 50 50 53 1/6/20101/7/20101/8/2010 90 90 92 93 89 92 95 94 93 94 88 79 78 74 68 67 68 73 78 61 64 70 1/9/2010

1/10/20101/11/2010 79 80 78 78 75 76 84 85 68 63 61 62 62 55 48 51 57 61 56 48 46 51 

Avg 72 73 72 72 73 73 76 77 69 62 59 56 56 54 51 54 60 65 65 67 67 66 

Max 90 90 93 97 97 96 97 97 95 96 95 96 95 95 95 95 96 95 95 93 93 92 

Min 54 55 46 46 51 46 45 49 52 40 38 37 37 30 27 31 37 46 49 48 46 50 

‐‐ Indicate invalid data

SAROAD for Barrick, RubyHill

Channel: RH_percent

Month: 12/09/09 ‐ 01/11/10

Hour of da

y

Non‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐Day

Non‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐Day

Non‐Run‐Day
Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

12/9/2009 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ 

12/10/200912/11/200912/12/2009 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ 12/13/200912/14/200912/15/2009 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ 12/16/200912/17/200912/18/2009 ‐‐ ‐‐ 604 604 604 604 605 605 605 605 605 604 604 604 604 604 604 604 604 604 604 605 

12/19/200912/20/200912/21/2009 600 600 600 600 600 599 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ 597 597 596 596 595 595 595 594 594 593 593 

12/22/200912/23/200912/24/2009 604 604 604 604 604 604 604 604 604 605 604 604 604 604 604 604 603 604 604 603 603 603 12/25/200912/26/200912/27/2009 600 600 600 600 600 600 600 601 601 601 601 601 601 601 601 602 602 602 602 602 602 602 12/28/200912/29/200912/30/2009 597 597 597 597 597 597 598 598 598 599 599 599 599 599 600 600 601 601 602 602 603 603 12/31/2009

1/1/20101/2/2010 603 603 603 603 603 604 604 604 604 604 604 604 604 603 603 603 604 604 604 604 604 604 1/3/20101/4/20101/5/2010 604 603 603 603 603 603 603 603 604 604 604 603 603 603 602 602 602 603 603 603 603 603 1/6/20101/7/20101/8/2010 604 604 604 604 604 604 604 604 604 604 604 604 604 603 603 603 604 604 604 604 604 604 1/9/2010

1/10/20101/11/2010 606 606 606 606 606 605 605 606 606 606 606 605 604 604 604 603 603 603 603 603 603 603 

Avg 602 602 602 602 602 602 603 603 603 603 603 602 602 602 602 602 602 602 602 602 602 602 

Max 606 606 606 606 606 605 605 606 606 606 606 605 604 604 604 604 604 604 604 604 604 605 

Min 597 597 597 597 597 597 598 598 598 599 599 597 597 596 596 595 595 595 594 594 593 593 

‐‐ Indicates invalid data

Non‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐DayNon‐Run‐Day

SAROAD for Barrick, RubyHill

Channel: BP_mmHg

Month: 12/09/09 ‐ 01/11/10

Hour of da

y
APPENDIX B 

HCN Data 
Page 1 of 2

Wed, 01/06/10 5:25 PM

ANALYTICAL REPORT

Tom Brauch

Air Sciences, Inc.

1301 Washington Ave, Suite 200

Golden, CO 80401

Phone:

E-mail:

(303) 988-2960 x 207

tbrauch@airsci.com

Report Date January 06, 2010

Project Manager Rand Potter

Workorder: 9365024

Purchase Order:

Client Project ID: Air Sciences 123109

59-57-5

Analytical Results

12/26/2009

9365024001 12/31/2009

Sample ID:

Lab ID:

Media: Collected:

Received:

595712262009-1 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/6/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

12/26/2009

9365024002 12/31/2009

Sample ID:

Lab ID:

Media: Collected:

Received:

595712262009-2 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/6/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

12/26/2009

9365024003 12/31/2009

Sample ID:

Lab ID:

Media: Collected:

Received:

595712262009-3 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/6/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

Report Authorization

Method: NIOSH 6010

Sarah E. Adamson Rosemary Hanks

Analyst Peer Review

Phone: (801) 266-7700

Email: lab@datachem.com

Web: www.datachem.com

Laboratory Contact Information

ALS Laboratory Group (formerly DataChem Laboratories, Inc.)

960 W Levoy Drive

Salt Lake City, Utah 84123

IHREP-V9.8
Page 2 of 2

Wed, 01/06/10 5:26 PM

ANALYTICAL REPORT

Project Manager Rand Potter

Workorder: 9365024

Purchase Order:

Client Project ID: Air Sciences 123109

59-57-5

The results provided in this report relate only to the items tested.

Samples were received in acceptable condition unless otherwise noted.

Samples have not been blank corrected unless otherwise noted.

This test report shall not be reproduced, except in full, without written approval of ALS Laboratory Group.

ALS Laboratory Group is accredited by AIHA for specific fields of testing as documented in its current scope of accreditation

(ID#101574) which is available on request by contacting your project manager or view on the internet at http://www.aiha.org. The

quality systems implemented in the laboratory apply to all methods performed by ALS Laboratory Group regardless of this current

scope of accreditation which does not include performance based methods, modified methods, and methods applied to matrices

not listed in the methods.

ALS DataChem provides professional analytical services for all samples submitted. ALS Laboratory Group is not in a position to

interpret the data and assumes no responsibility for the quality of the samples submitted.

All quality control samples processed with the samples in this report yielded acceptable results unless otherwise noted.

General Lab Comments

LOD = Limit of Detection = MDL = Method Detection Limit, A statistical estimate of method/media/instrument sensitivity.

LOQ = Limit of Quantitation = RL = Reporting Limit, A verified value of method/media/instrument sensitivity.

ND = Not Detected, Testing result not detected above the LOD or LOQ.

** No result could be reported, see sample comments for details.

< This testing result is less than the numerical value.

( ) This testing result is between the LOD and LOQ and has higher analytical uncertainty than values at or above the LOQ.

Definitions

IHREP-V9.8

Page 1 of 2

Wed, 01/13/10 2:14 PM

ANALYTICAL REPORT

Tom Brauch

Air Sciences, Inc.

1301 Washington Ave, Suite 200

Golden, CO 80401

Phone:

E-mail:

(303) 988-2960 x 207

tbrauch@airsci.com

Report Date January 13, 2010

Project Manager Rand Potter

Workorder: 1000617

Purchase Order:

Client Project ID: Ruby Hill 59-57-5 010610

59-57-5

Analytical Results

1/3/2010

1000617001 1/6/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

595701032010-1 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/12/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

1/3/2010

1000617002 1/6/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

595701032010-2 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/12/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

1/3/2010

1000617003 1/6/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

595701032010-3 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/12/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

Report Authorization

Method: NIOSH 6010

Sarah E. Adamson Rosemary Hanks

Analyst Peer Review

Phone: (801) 266-7700

Email: lab@datachem.com

Web: www.datachem.com

Laboratory Contact Information

ALS Laboratory Group (formerly DataChem Laboratories, Inc.)

960 W Levoy Drive

Salt Lake City, Utah 84123

IHREP-V9.8
Page 2 of 2

Wed, 01/13/10 2:14 PM

ANALYTICAL REPORT

Project Manager Rand Potter

Workorder: 1000617

Purchase Order:

Client Project ID: Ruby Hill 59-57-5 010610

59-57-5

The results provided in this report relate only to the items tested.

Samples were received in acceptable condition unless otherwise noted.

Samples have not been blank corrected unless otherwise noted.

This test report shall not be reproduced, except in full, without written approval of ALS Laboratory Group.

ALS Laboratory Group is accredited by AIHA for specific fields of testing as documented in its current scope of accreditation

(ID#101574) which is available on request by contacting your project manager or view on the internet at http://www.aiha.org. The

quality systems implemented in the laboratory apply to all methods performed by ALS Laboratory Group regardless of this current

scope of accreditation which does not include performance based methods, modified methods, and methods applied to matrices

not listed in the methods.

ALS DataChem provides professional analytical services for all samples submitted. ALS Laboratory Group is not in a position to

interpret the data and assumes no responsibility for the quality of the samples submitted.

All quality control samples processed with the samples in this report yielded acceptable results unless otherwise noted.

General Lab Comments

LOD = Limit of Detection = MDL = Method Detection Limit, A statistical estimate of method/media/instrument sensitivity.

LOQ = Limit of Quantitation = RL = Reporting Limit, A verified value of method/media/instrument sensitivity.

ND = Not Detected, Testing result not detected above the LOD or LOQ.

** No result could be reported, see sample comments for details.

< This testing result is less than the numerical value.

( ) This testing result is between the LOD and LOQ and has higher analytical uncertainty than values at or above the LOQ.

Definitions

IHREP-V9.8

Page 1 of 2

Wed, 01/20/10 1:23 PM

ANALYTICAL REPORT

Tom Brauch

Air Sciences, Inc.

1301 Washington Ave, Suite 200

Golden, CO 80401

Phone:

E-mail:

(303) 988-2960 x 207

tbrauch@airsci.com

Report Date January 20, 2010

Project Manager Rand Potter

Workorder: 1001934

Purchase Order:

Client Project ID: Air Sciences Inc 011910

59-57-5

Analytical Results

1/5/2010

1001934001 1/19/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

5957152010-1 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

1/5/2010

1001934002 1/19/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

5957182010-2 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

Hydrogen Cyanide 0.32 NA NA 0.21

1/5/2010

1001934003 1/19/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

59571112010-3 SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

1/5/2010

1001934004 1/19/2010

Sample ID:

Lab ID:

Media: Collected:

Received:

Field Blank SKC 226-28, Soda Lime-200/600

Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm

NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

Hydrogen Cyanide <0.21 NA NA 0.21

IHREP-V9.8
Page 2 of 2

Wed, 01/20/10 1:23 PM

ANALYTICAL REPORT

Project Manager Rand Potter

Workorder: 1001934

Purchase Order:

Client Project ID: Air Sciences Inc 011910

59-57-5

Report Authorization

Method: NIOSH 6010

Sarah E. Adamson Rosemary Hanks

Analyst Peer Review

Phone: (801) 266-7700

Email: lab@datachem.com

Web: www.datachem.com

Laboratory Contact Information

ALS Laboratory Group (formerly DataChem Laboratories, Inc.)

960 W Levoy Drive

Salt Lake City, Utah 84123

The results provided in this report relate only to the items tested.

Samples were received in acceptable condition unless otherwise noted.

Samples have not been blank corrected unless otherwise noted.

This test report shall not be reproduced, except in full, without written approval of ALS Laboratory Group.

ALS Laboratory Group is accredited by AIHA for specific fields of testing as documented in its current scope of accreditation

(ID#101574) which is available on request by contacting your project manager or view on the internet at http://www.aiha.org. The

quality systems implemented in the laboratory apply to all methods performed by ALS Laboratory Group regardless of this current

scope of accreditation which does not include performance based methods, modified methods, and methods applied to matrices

not listed in the methods.

ALS DataChem provides professional analytical services for all samples submitted. ALS Laboratory Group is not in a position to

interpret the data and assumes no responsibility for the quality of the samples submitted.

All quality control samples processed with the samples in this report yielded acceptable results unless otherwise noted.

General Lab Comments

LOD = Limit of Detection = MDL = Method Detection Limit, A statistical estimate of method/media/instrument sensitivity.

LOQ = Limit of Quantitation = RL = Reporting Limit, A verified value of method/media/instrument sensitivity.

ND = Not Detected, Testing result not detected above the LOD or LOQ.

** No result could be reported, see sample comments for details.

< This testing result is less than the numerical value.

( ) This testing result is between the LOD and LOQ and has higher analytical uncertainty than values at or above the LOQ.

Definitions

IHREP-V9.8

APPENDIX C 

Site Check Forms, Audits, and Calibration 
Calibration Form

Ruby Hill Air Quality and Meteorological Monitoring

Site: Ruby Hill Technician: Tom Brauch

Date: Site Conditions: Cold, Windy

Invalid Data Range: Before 12/07/2009 Logger Serial Number: 3012

Initial Prior to Departure Initials

Data download (record date and time). TWB

Time and date verified on datalogger. TWB

Communications verified. TWB

All public real‐time values are confirmed and as expected. TWB

WS/WD verification performed (complete audit form). N/A

Temperature and RH verification performed (complete audit form). TWB

Precipitation verification performed (complete audit form). N/A

Barometric pressure verification performed (complete audit form). TWB

Solar panel cleaned. TWB

Comments:

Site was installed and became operational on 12/07/2009

All sensors were calibrated

Signature Date:

12/7/2009

12/7/2009

59‐57‐12072009CALAQ‐MET 1
Calibration Form

Ruby Hill Air Quality and Meteorological Monitoring

Time: 17:00 to 18:00 PST Time: 17:00 to 18:00 PST

Diff Diff

1. ‐4.1 1. ‐3.9 ‐0.2 1. 63 1. 60 3

2. ‐4.1 2. ‐3.9 ‐0.2 2. 63 2. 60 3

3. ‐4.2 3. ‐4.1 ‐0.1 3. 62 3. 60 2

4. ‐4.2 4. ‐4.1 ‐0.1 4. 62 4. 61 1

5. ‐4.2 5. ‐4.2 0.0 5. 63 5. 61 2

6. ‐4.3 6. ‐4.2 ‐0.1 6. 62 6. 61 1

7. ‐4.3 7. ‐4.3 0.0 7. 62 7. 62 0

8. ‐4.3 8. ‐4.3 0.0 8. 62 8. 62 0

9. ‐4.3 9. ‐4.3 0.0 9. 60 9. 62 ‐2

10. ‐4.4 10. ‐4.3 ‐0.1 10. 60 10. 61 ‐1

Average Difference ‐0.1 0.9

Difference = Site ‐ Measured

Time: 17:00 PST

Diff *

1. 611.0 1. 610 1

2. 611.0 2. 610 1

3. 612.0 3. 610 2

4. 611.0 4. 610 1

Average Difference 1.25

*Difference = Site ‐ Measured

Measured

Brunton Altimeter

VWR Thermo Hygro

SN: D3250101 SN: 80357103

VWR Thermo Hygro HMP45C Logger

Temperature

HMP45C Logger

Measured

mmHg

Barometric Pressure ‐ Co‐Located Calibration

SN: NA

Barometric Pressure

SN: D3250101

mmHg

SN: 80357103

Temperature and Relative Humidity ‐ Co‐Located Calibration

Relative Humidity Measured

Logger Reading

SN: D3140098

59‐57‐12072009CALAQ‐MET 2
Calibration Form

Ruby Hill Air Quality and Meteorological Monitoring

Time : 17:00 to 18:00 MST

Diff * Diff *

1. 0.0 1. 0.0 0.0 1. 0 1. 2 ‐2

2. 1.0 2. 1.0 0.0 2. 45 2. 44 1

3. 2.0 3. 2.0 0.0 3. 90 3. 89 1

4. 3.1 4. 3.1 0.0 4. 135 4. 132 3

5. 4.1 5. 4.1 0.0 5. 180 5. 179 1

6. 5.1 6. 5.1 0.0 6. 225 6. 223 2

7. 10.2 7. 10.2 0.0 7. 270 7. 270 0

8. 15.4 8. 15.4 0.0 8. 315 8. 312 3

9. 20.5 9. 20.5 0.0

10. 25.6 10. 25.6 0.0

Average Difference 0 1.125

*Difference = Site ‐ Measured

Comments:

Signature Date:

Wind Speed Wind Speed Wind Direction Wind Direction

Standard Site Standard Site

Motor R. M. Young (m/s) Sensor Base R. M. Young (deg)

SN: Set C SN: 79696

Wind Speed and Wind Direction Gill 2‐D Sonic ‐ Co‐Located Sensor Comparison ‐ Real‐Time Comparison

SN: 79696

12/7/2009

59‐57‐12072009CALAQ‐MET 3
Calibration Form

Ruby Hill Air Quality and Meteorological Monitoring

Time: 17:00 ‐ 18:00 PST

1. 33.9 1. 49.97 1. 49.6 1. 1.060 1. 0.847 1. 0.06461

2. 31.1 2. 45 2. 45.1 2. 1.000 2. 0.862 2. 0.06095

3. 28.37 3. 40.5 3. 40.7 3. 0.927 3. 0.876 3. 0.0565

4. 23.58 4. 34.1 4. 34.3 4. 0.808 4. 0.896 4. 0.04925

5. 20.16 5. 30.1 5. 30.2 5. 0.731 5. 0.908 5. 0.04456

6. 16.75 6. 25.1 6. 25.1 6. 0.634 6. 0.923 6. 0.03864

7. 7. 7. 7. 7. 7.

8. 8. 8. 8. 8. 8.

9. 9. 9. 9. 9. 9.

10. 10. 10. 10. 10. 10.

25.643333 37.4617 37.5 0.86

a

Difference = Site ‐ Measured b

Difference = ((Site – Measured)/Measured)*100

Notes for next trip:

Signature Date:

Temp (

o

C) BP (mm Hg)

‐4 611

P1/Pa Qa (Flow Meter)

Tube 1 Flow Tube 2 Flow Tube 3 Flow

‐2.8628 1.0356 ‐0.9972

SN: 35543F3

Slope Intercept Correlation

SN: 35542F3 SN: SN: 35545F3 35583F3

Inches Digital

Raw Inches Sampler Manometer

HCN Sampler System

Flow (L/min) Low

Flow BIOS

12/7/2009

mV Pressure Transducer

59‐57‐12072009CALAQ‐MET 4
APPENDIX D 

Hydrogen Cyanide (HCN) Fence Line Monitoring Plans 

Site-Specific Hydrogen 

Cyanide (HCN) Fence 

Line Monitoring Plan 

HOMESTAKE MINING 

COMPANY OF CALIFORNIA,

BARRICK RUBY HILL MINE

PROJECT 59-51-3 

OCTOBER 2009 

UPDATED NOVEMBER 24, 2009 
 ii 

CONTENTS Page

1 INTRODUCTION ............................................................................................................................................................ 1

1.1 Mine Description and Proposed Monitoring ............................................................................................................ 1

2 METEOROLOGY ........................................................................................................................................................... 2

2.1 Prevailing Wind Direction ........................................................................................................................................ 2

3 PROPOSED HCN MONITORING SITE ......................................................................................................................... 4

3.1 Operations Boundary and Nearest Population Areas ............................................................................................. 4

3.2 Potential Sources of HCN ....................................................................................................................................... 4

3.3 Proposed HCN Monitor Location ............................................................................................................................ 4

4 PROPOSED MODIFICATIONS TO THE GENERAL HCN MONITORING PLAN ......................................................... 8

Figures 

Figure 2.1: Calendar Year 2008 Wind Rose .................................................................................................................... 2

Figure 2.2: Calendar Quarter Wind Roses for 2008 ......................................................................................................... 3

Figure 3.1: Proposed HCN Monitoring Site ...................................................................................................................... 5

Figure 3.2: Large Scale Area Map ................................................................................................................................... 6

Figure 3.3: Refinery .......................................................................................................................................................... 7

Appendices 

Appendix A: Hydrogen Cyanide (HCN) Fence Line Monitoring Plan 

 
 1 

SECTION 1 

INTRODUCTION 

1.1 Mine Description and Proposed Monitoring 

Homestake Mining Company of California, Barrick Ruby Hill Mine (Ruby Hill) operates a gold 

mining facility located 0.7 mile northwest of Eureka, Nevada on Highway 50. The facility 

operates an open-pit mine. Gold recovery operations include: ore crushing, heap leaching, 

carbon adsorption, stripping and regeneration, electrowinning, retorting, and refining. The leach 

solutions used in the gold recovery processes contain cyanide. These solutions have the potential 

for low levels of hydrogen cyanide (HCN) formation and emission to the atmosphere. To assess 

the ambient concentrations of HCN, Ruby Hill plans to install and operate an HCN monitor 

downwind of the potential HCN sources near the Ruby Hill operations area. 

The HCN monitoring equipment and sampling procedures will follow the Hydrogen Cyanide 

(HCN) Fence Line Monitoring Plan, approved by EPA on October 9, 2009 (General HCN 

Monitoring Plan). This plan is provided in Appendix A. The purposes of the site-specific plan 

described herein are to identify the location where the monitor will be sited and to identify any 

modifications to the monitoring equipment and sampling procedures described in the General 

HCN Monitoring Plan that are specific to Ruby Hill. Per EPA’s instructions, the site location 

takes into consideration the proximity of the HCN sources to public access areas and the 

prevailing wind direction. The site location also takes into consideration accessibility for the 

Ruby Hill maintenance and project technicians. 

The following sections describe the predominant wind direction, the Ruby Hill operations 

boundary, the nearest population areas to this boundary, the potential sources of HCN emissions 

and their locations, and the proposed HCN monitor site. 

The HCN monitoring system proposed herein is a new system. Typically, a full field test and 

system verification of such a prototype monitor would be scheduled in advance of deploying the 

monitor for data collection. This is done in order to identify system design problems, and refine 

the system configuration and operating and maintenance procedures as appropriate. Due to the 

schedule that EPA has requested, only limited field testing and system verification will be 

possible prior to data collection. Because of this, it is possible that problems may arise with the 

monitoring system which will affect data collection; however, Ruby Hill will take all reasonable 

measures to avoid such problems in an effort to minimize any disruptions to the monitoring 

program. 
 2 

SECTION 2 

METEOROLOGY 

2.1 Prevailing Wind Direction 

Ruby Hill currently operates a meteorological station. This station is located in the nearby town 

of Eureka, Nevada, approximately 0.7 mile southeast of the mine. Figure 2.1 summarizes the 

hourly wind directions (the direction from which the wind is blowing) and wind speeds for the 

2008 calendar year. Figure 2.2 provides wind roses for each calendar quarter of 2008. As shown 

by the annual and quarterly wind roses, the prevailing wind direction is from the southsoutheast.1 However, there is also a significant amount of winds (26 percent combined) from the 

west-northwest to the north-northwest. These winds blow directly towards the town of Eureka 

from the potential HCN sources at Ruby Hill. 

Figure 2.1: Calendar Year 2008 Wind Rose 

 

 

1 The Ruby Hill meteorological station is missing data for nearly the entire month of October 2008. Therefore, data from 

the Eureka airport National Weather Service meteorological station was substituted for this period. This airport station is 

approximately 4.5 miles north of the mine. 

4%

8%

12%

16%

20%

24%

28%

32%

36%

40%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

2 4 8 12 18 mph

Wind Frequency Distribution - Hourly Met. Data

01/01/08 - 12/31/08

Calm hours = 380 Missing hours =62

Number of non-calm/missing hours = 8342
 3 

Figure 2.2: Calendar Quarter Wind Roses for 2008 

 First Quarter Second Quarter 

 01/01/08 - 03/31/08 04/01/08 - 06/30/08 

 Third Quarter Fourth Quarter 

 07/01/08 - 09/30/08 10/01/08 - 12/31/08 

4%

8%

12%

16%

20%

24%

28%

32%

36%

40%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

2 4 8 12 18 mph

Wind Frequency Distribution - Hourly Met. Data

01/01/08 - 03/31/08

Calm hours = 109 Missing hours = 0

Number of non-calm/missing hours = 2,075

4%

8%

12%

16%

20%

24%

28%

32%

36%

40%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

2 4 8 12 18 mph

Wind Frequency Distribution - Hourly Met. Data

04/01/08 - 06/30/08

Calm hours = 47 Missing hours = 0

Number of non-calm/missing hours = 2,137

4%

8%

12%

16%

20%

24%

28%

32%

36%

40%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

2 4 8 12 18 mph

Wind Frequency Distribution - Hourly Met. Data

07/01/08 - 09/30/08

Calm hours = 61 Missing hours = 0

Number of non-calm/missing hours = 2,147

4%

8%

12%

16%

20%

24%

28%

32%

36%

40%

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

2 4 8 12 18 mph

Wind Frequency Distribution - Hourly Met. Data

10/01/08 - 12/31/08

Calm hours = 163 Missing hours = 62

Number of non-calm/missing hours = 1,983
 4 

SECTION 3 

PROPOSED HCN MONITORING SITE 

3.1 Operations Boundary and Nearest Population Areas 

Aerial photos and shaded relief maps are proved as Figures 3.1 through 3.3. Figure 3.1 provides 

an aerial photo of the mine site, the operations boundary, and the potential HCN sources. The 

operations boundary represents a fence line on the east side and the boundary of the land 

privately owned and controlled by Ruby Hill on the west side. 

Figure 3.2 provides a shaded relief map of the area surrounding the Ruby Hill mine. The nearest 

town is Eureka, located approximately 0.7 mile southeast of the Ruby Hill mine. Eureka is a 

town of approximately 1,600 residents. There is also a small community approximately 1.5 miles 

northwest of the mine. Based on a visual survey from Google Earth©, there are approximately 

two dozen structures in the community. 

3.2 Potential Sources of HCN 

Figures 3.1 and 3.3 highlight the potential sources of HCN emissions at Ruby Hill. These sources 

include an active leach pad, Carbon-in-Column (CIC) tanks, pregnant and barren ponds, a 

pregnant tank adjacent to the pregnant and barren ponds, a barren tank adjacent to the leach pad, 

and a single stack for the electrowinning cells and pregnant and barren tanks at the refinery. A 

closer view of the refinery area is shown in Figure 3.3. 

3.3 Proposed HCN Monitor Location 

Ruby Hill proposes to place the HCN monitor at a property owned by Ruby Hill on the north 

end of the town of Eureka. As shown in Figure 3.1, the proposed location is approximately 0.5 

mile southeast of the mine. As discussed in Section 2.1, 29 percent of the winds are from the 

south-southeast and 26 percent of the winds are from the west-northwest to the north-northwest. 

The west-northwest to the north-northwest winds blow directly towards the town of Eureka from 

the potential HCN sources. Eureka is the largest population center near the mine site and the 

monitoring data collected here will inform the EPA of the HCN exposure to the Eureka residents. 

The proposed monitor location has line power and is accessible via a road maintained by Ruby 

Hill. The proposed site coordinates are 588,792 meters east, 4,375,085 meters north, UTM Zone 

11N, NAD83, elevation 6,544 feet. 

 
5
6
7
 8 

SECTION 4 

PROPOSED MODIFICATIONS TO THE GENERAL HCN 

MONITORING PLAN 

Ruby Hill does not propose any modifications to the General HCN Monitoring Plan with regards 

to the HCN and meteorological sampling equipment. Ruby Hill does propose to modify the 

sampling duration in the General HCN Monitoring Plan to monitor HCN concentrations at the 

proposed location for an extra month, totaling three months of monitoring. 

As discussed in Section 3.3, line power is available at the proposed HCN monitor location. 

Therefore, the solar power system described in the General HCN Monitoring Plan will not be 

needed. 
APPENDIX A 

Hydrogen Cyanide (HCN) Fence Line Monitoring Plan 

Hydrogen Cyanide 

(HCN) Fence Line 

Monitoring Plan 

NEVADA MINING ASSOCIATION

PROJECT 59-43-70 

OCTOBER 2009 
Hcn Sampling Plan_V7.Docx ii 

CONTENTS Page

1 PROJECT MANAGEMENT ELEMENTS ....................................................................................................................... 1 

1.1 Sampling Purpose .................................................................................................................................................. 1

1.2 System Description ................................................................................................................................................. 1

2 QUALITY OBJECTIVES AND CRITERIA FOR DATA MEASUREMENT ...................................................................... 3

2.1 Data Quality Objectives and Criteria ....................................................................................................................... 3

3 SPECIAL TRAINING REQUIREMENTS/CERTIFICATION ........................................................................................... 4

4 DOCUMENTATION OF RECORDS .............................................................................................................................. 5

4.1 Data Reporting Package Format and Documentation Control ............................................................................... 5

5 DATA GENERATION AND ACQUISITION .................................................................................................................... 6

5.1 Sampling Process Design and Methods Requirements ......................................................................................... 6

5.1.1 Purpose ........................................................................................................................................................... 6

5.1.2 Sampling Network Design ............................................................................................................................... 6

5.1.3 Equipment Description .................................................................................................................................... 7

5.1.4 Data Logger ..................................................................................................................................................... 7

5.1.5 Wind Speed ..................................................................................................................................................... 7

5.1.6 Wind Direction ................................................................................................................................................. 8

5.1.7 Temperature Sensor and Radiation Shield ..................................................................................................... 8

5.1.8 Relative Humidity ............................................................................................................................................ 8

5.1.9 Barometric Pressure ........................................................................................................................................ 8

5.1.10 HCN Sampling System .................................................................................................................................. 8

5.1.11 Power and Data Transfer ............................................................................................................................ 12

5.1.12 Meteorological Towers ................................................................................................................................ 12

5.2 Rationale for Design ............................................................................................................................................. 12

5.3 Scheduled Measurement Activities ....................................................................................................................... 12

5.4 Measurement System Failure Response .............................................................................................................. 13

6 SAMPLING METHOD REQUIREMENTS .................................................................................................................... 14

6.1 Sample Handling and Custody Requirements ...................................................................................................... 14

6.2 Analytical Methods Requirements and Breakthrough Check ............................................................................... 14

6.3 Quality Control Requirements ............................................................................................................................... 14

7 INSTRUMENT/EQUIPMENT TESTING, INSPECTION, AND MAINTENANCE REQUIREMENTS ............................ 16

7.1 General Procedures .............................................................................................................................................. 16

7.2 Instrument Calibration and Frequency .................................................................................................................. 16

7.2.1 Calibration Equipment Maintenance ............................................................................................................. 16

7.2.2 Calibration Records and Traceability ............................................................................................................ 17

8 INSPECTION/ACCEPTANCE REQUIREMENTS FOR SUPPLIES AND CONSUMABLES ....................................... 18

9 DATA MANAGEMENT ................................................................................................................................................. 19

9.1 Data Custody ........................................................................................................................................................ 19

10 DATA VALIDATION AND USABILITY ....................................................................................................................... 20

10.1 Data Review, Validation, and Certification .......................................................................................................... 20

10.1.1 Data Validation ............................................................................................................................................ 20

10.1.2 Data Collection ............................................................................................................................................ 20

10.1.3 Data Reduction ............................................................................................................................................ 20

10.2 Validation Methods ............................................................................................................................................. 21

10.2.1 Data Review and Validation Requirements ................................................................................................. 21 
Hcn Sampling Plan_V7.Docx iii 

CONTENTS - Continued Page

Tables 

Table 1: Sensor Height on Towers ................................................................................................................................... 2

Table 2: System Accuracies and Resolution .................................................................................................................... 3

Table 3: System Performance and Data Custody Forms ................................................................................................. 5

Table 4: System Components .......................................................................................................................................... 6

Table 5: Sampling Frequency ........................................................................................................................................ 12

Table 6: Scheduled Sampling Activities ......................................................................................................................... 13

Table 7: Project Quality Control Checks ........................................................................................................................ 15

Table 8: Preventive Maintenance Schedule ................................................................................................................... 16

Table 9: Calibration Equipment Testing ......................................................................................................................... 17

Table 10: Data Recorded on Site ................................................................................................................................... 20

Figures 

Figure 1: HCN Sampling System Flow Diagram - Static Mode ........................................................................................ 9

Figure 2: HCN Sampling System Flow Diagram - Warm-Up Mode ............................................................................... 10

Figure 3: HCN Sampling System Flow Diagram - Sampling Mode Sorbent Tube 1 ...................................................... 11

Appendices 

Appendix A: NIOSH Method 6010
Hcn Sampling Plan_V7.Docx 1 

SECTION 1 

PROJECT MANAGEMENT ELEMENTS 

1.1 Sampling Purpose 

This sampling plan is being developed to determine the levels of hydrogen cyanide (HCN) in 

ambient air at the fence line of a mine site. This plan describes the general HCN sampling 

equipment, collection methods, and data recording procedures. Separate site-specific plans will 

be submitted for individual mine sites where HCN monitoring will take place. The site-specific 

plans will be in accordance with this general plan unless otherwise noted, in which case the 

specific plan will take precedence. 

There is currently no EPA method for measuring trace levels of HCN in ambient air. The method 

described in this monitoring plan was developed using some elements of both EPA and NIOSH 

sampling and analytical guidelines. Meteorological parameters will be collected. In addition, an 

optional video surveillance system may be deployed to determine the operability of the sampler 

as well as identify any unusual conditions at the sampler. 

The design of the system uses elements of U.S. EPA Quality Assurance Handbook of Air Pollution 

Measurement Systems Volume II as well as the NIOSH Manual of Analytical Methods, Method 6010. 

All meteorological parameters will be collected consistent with U.S. EPA Quality Assurance 

Handbook of Air Pollution Measurement Systems Volume IV - Meteorological Measurements (EPA600/R94-038D), March 1995, and as provided in this plan. 

1.2 System Description 

The system will consist of a data logger connected to a low-flow pump which is connected 

through sorbent tubes to an ambient air inlet. The sorbent tubes will capture any HCN in the 

ambient air and will be sent to a certified lab for analysis. The sampling schedule will follow a 1-

in-3 day calendar for a period of two months. During a run day, all parameters will be collected 

every two seconds and time-averaged into 15-minute values. The parameters collected are 

shown in Table 1. Wind speed, wind direction, ambient temperature, relative humidity, and 

barometric pressure are collected as well as flow rate through the sorbent tubes. 

The measurement height of the inlet is two meters. The height of the wind instruments will be 

3.5 meters. All other parameters are measured at 2 meters. 
Hcn Sampling Plan_V7.Docx 2 

Table 1: Sensor Height on Towers 

(meters above ground) 

Parameter Height 

Wind speed 3.5 

Wind direction 3.5 

Ambient temperature 2 

Relative humidity 2 

Barometric pressure 2 

Sampler Flow 2 
Hcn Sampling Plan_V7.Docx 3 

SECTION 2 

QUALITY OBJECTIVES AND CRITERIA FOR DATA 

MEASUREMENT 

2.1 Data Quality Objectives and Criteria 

The primary quality objectives are taken from EPA guidance where applicable. The following 

tables present the guidelines for each sensor as well as the relevant references for each. 

Table 2: System Accuracies and Resolution 

Parameter Sensor* Range Accuracy Standard 

Measurement 

Resolution Reference 

Wind 

direction 

R.M. Young 

05305-AQ 

Range: 0° to 

360°

+3° Accuracy: 

+5° 1.0° EPA-454/4-87-007 

Section 6.1.1, 

EPA-454/R-99-005, 

February 2000, 

Table 5-1 

Wind speed R.M. Young 

05305-AQ 

0.4 to 45 m/s +0.2 m/s Accuracy: 

+0.25 m/s 

up to 

speeds of 5 

m/s and 

+5% 

thereafter 

0.1 m/s EPA-454/4-87-007 

Section 6.1.1 

EPA-454/R-99-005, 

February 2000, 

Table 5-1 

Ambient 

temp. 

Campbell 

Scientific 

Model 

HMP45C 

-39.2°C to 

+60°C 

+0.3° +0.5°C 0.1°C EPA-454/4-87-007 

Section 6.1.5 

EPA-454/R-99-005, 

February 2000, 

Table 5-1 

Relative 

humidity 

Campbell 

Scientific 

Model 

HMP45C 

0.8 to 100% +2% (0-90% 

RH) and 

+3% (90-

100% RH) 

1.5°C dew 

point 

temperature 

error 

1% EPA-454/4-87-007 

Section 6.1.4 

EPA-454/R-99-005, 

February 2000, 

Table 5-1 

Barometric 

pressure 

Vaisala 

PT101B 

-40°C to 60°C +0.5 mb +3 mb +0.1 mb EPA-454/4-87-007 

Section 6.1.7 

EPA-454/R-99-005, 

February 2000, 

Table 5-1 

Flow rate Pressure 

transducer 

N/A +5% +10% of 

observed 

0.1 l/min N/A 

* Or equivalent sensor. 
Hcn Sampling Plan_V7.Docx 4 

SECTION 3 

SPECIAL TRAINING REQUIREMENTS/CERTIFICATION 

The monitoring equipment should be operated under the guidance of the Project Technician. The 

Project Technician will receive training in the equipment operation. Any non-routine work on 

this system must be conducted by a qualified technician. 
Hcn Sampling Plan_V7.Docx 5 

SECTION 4 

DOCUMENTATION OF RECORDS 

All of the forms which will be used to document the system performance and data custody are 

listed in Table 3. 

Table 3: System Performance and Data Custody Forms 

Component 

Hard Copy or 

Electronic Copy Comments 

Site Check Form Hard Copy Include check of flow and 

meteorological sampling. 

Chain of Custody Form Hard Copy Record handling of sorbent tube 

through analytical process. 

Site-Specific Journal Record Hard Copy and 

Electronic Copy 

Record any anomalous 

occurrences. 

Flow Audit Hard Copy and 

Electronic Copy 

Conduct at end of 2 month 

sampling period. 

4.1 Data Reporting Package Format and Documentation Control 

A report will be prepared and submitted to EPA within 30 days of the conclusion of the data 

collection program. The report will contain: 

• A calculation of the percentage of valid data collected with an explanation of any 

instrument malfunction for each parameter, 

• All valid hourly meteorological data, 

• All valid flow data, 

• All HCN concentrations determined by laboratory analysis, 

• Copies of Site Check Forms, 

• Copies of any calibrations and audits performed, 

• Anecdotally conveyed notes and anomalies, and 

• Corrective actions taken (if any). 

After the first four weeks of sampling, preliminary data will be supplied to EPA after the 

analyses are received from the laboratory. 
Hcn Sampling Plan_V7.Docx 6 

SECTION 5 

DATA GENERATION AND ACQUISITION 

5.1 Sampling Process Design and Methods Requirements 

5.1.1 Purpose 

The monitoring requirements subject to EPA and federal guidelines are strictly defined for 

meteorology but not for HCN. The equipment selection and operation of the station is in 

accordance with available guidelines. In cases where an existing meteorological station at the 

mine meets all applicable guidelines, this station may be used in lieu of the meteorological 

equipment specified herein. The site-specific plan submitted by each mine will address the 

proposed location of the meteorological monitoring station that will be used to provide 

meteorological data for the ambient fence line monitoring program. 

5.1.2 Sampling Network Design 

The monitoring system will consist of the following parts, or equivalent, as specified in the sitespecific plan. Each part will have a serial number and will be calibrated upon installation. 

Table 4: System Components 

Item Manufacturer Model Name 

Enclosure Campbell Scientific ENC 12/14 

3-meter tower Campbell Scientific 25G 

Wind sensor mount Campbell Scientific 019ALU 

Pyranometer mounting arm Campbell Scientific 015ARM 

Data logger CR3000 Campbell Scientific CR23X or CR10X 

Power supply with battery Campbell Scientific PS12LA 

Solar panel Campbell Scientific MSX10R 

Wind sensor R.M. Young Wind Monitor 05305-AQ 

Wind sensor cable R.M. Young 

Solar power system Kyocera Solar Electric System 

Temperature and relative humidity 

sensor 

Campbell Scientific HMP45C 

Barometric pressure sensor Vaisala PT101B 

Flow meter Newark Electronics TE525 

Flow meter Newark Electronics Pressure Transducer 
Hcn Sampling Plan_V7.Docx 7 

5.1.3 Equipment Description 

The following section describes the air quality and meteorological instrumentation that will be 

used for the HCN monitoring program. The instrumentation is selected consistent with the 

requirements of: 

• U.S. EPA Quality Assurance Handbook of Air Pollution Measurement Systems Volume II, 

September 1997. 

• NIOSH Manual of Analytical Methods, Method 6010, August 1994.

• U.S. EPA Quality Assurance Handbook of Air Pollution Measurement Systems Volume IV - 

Meteorological Measurements (EPA-454/B-08-002), March 2008. 

The data collection systems are designed to exceed the recommended quarterly data recovery 

rate of 90 percent for all meteorological parameters and 75 percent for HCN. 

5.1.4 Data Logger 

A Campbell Scientific, Inc. Model CR3000 data logger is used as the digital acquisition system for 

the stations. The data logger records the data every two seconds, computes 15-minute averages 

of each of the meteorological parameters, and stores the averages in its internal memory. The 

CR3000 has 4 mB of Flash Electrically Erasable Programmable Read Only Memory (EEPROM) for 

the operating system and user programs. It also has 512K of Static Random Access Memory 

(SRAM) used for storing approximately three months of data and running the program. It has a 

16-bit micro-controller with 32-bit internal CPU architecture. The resolution and accuracy of the 

analog inputs are 6.67 microvolts and ±0.04%, respectively. The CR3000 is equipped with a solidstate storage module. The 15-minute averages are written to the CR3000's internal memory and 

to the external storage module. The storage module can store nearly six months of data and will 

provide a backup of the data and the CR3000 program in the unlikely event of a power loss. The 

data logger is designed to operate in temperatures from –25°C to 50°C. 

5.1.5 Wind Speed 

Wind speed is continuously measured using an R.M. Young Model 05305 sensor interfaced 

directly to the data logger. The wind speed sensor of the Model 05305 is a helicoid-shaped, fourblade propeller. Rotation of the propeller produces an AC sine wave; the frequency is directly 

proportional to the wind speed. The AC signal is induced in a transducer coil by a six-pole 

magnet mounted on the propeller shaft. The coil is located on the non-rotating central portion of 

the main mounting assembly, eliminating the need for slip rings and brushes. Power for the 

sensor is supplied by the data logger. The Model 05305 has a range of 0.4 - 45 m/s, a starting 

threshold of 0.4 m/s, an accuracy of 0.2 m/s, and a distance constant of 2.1 meters. 
Hcn Sampling Plan_V7.Docx 8 

5.1.6 Wind Direction 

Wind direction is also continuously measured using an R.M. Young Model 05305 sensor 

interfaced directly to the data logger. The Model 05305 sensor provides a 1° to 360° format 

through the use of a precision potentiometer powered by the data logger. The potentiometer 

outputs a varying voltage proportional to the wind direction in degrees. The sensor is 

constructed from lightweight thermoplastic materials to give it a starting threshold of less than 

0.5 m/s. The sensor has an accuracy of ±3°, a damping ratio of 0.45, and a delay distance of less 

than 2 meters. 

5.1.7 Temperature Sensor and Radiation Shield 

The temperature measurements are continuously monitored using a Campbell Scientific 

HMP45C Platinum Resistance Temperature (PRT) detector. Temperature is measured by the 

data logger as a varying resistance across a platinum resistor that is proportional to the ambient 

temperature. The range of the sensor is –40°C to +60°C. The radiation shield for the temperature 

sensor prevents interference from solar radiation. The radiation error is less than 0.1°F. 

5.1.8 Relative Humidity 

Relative humidity is continuously measured using a Campbell Scientific Model HMP45C sensor. 

The HMP45C contains a Vaisala HUMICAPTM 180 capacitive relative humidity sensor. The 

HMP45C sensor is housed inside a non-aspirated shield. Relative humidity is measured by the 

data logger as an output voltage. The range of the sensor is from 0.8 to 100% (non-condensing) 

with an accuracy of ±2% when the humidity is less than 90%, and ±3% when the humidity is 

greater than 90%. The response time for the relative humidity sensor is 15 seconds. 

5.1.9 Barometric Pressure 

Barometric pressure is measured every 15 minutes using a Vaisala PT101B sensor. The sensor is 

mounted inside the data logger enclosure. Barometric pressure is measured by the data logger 

using Vaisala’s Barocap silicon capacitive pressure sensor, which outputs a linear 0 to 2.5 VDC 

signal. The operating range of the sensor is –40°C to 60°C. The CS105 has a warm-up time of one 

second, an uncertainty of 0.15 millibar, and a linearity of 0.45 millibar. 

5.1.10 HCN Sampling System 

This instrument is designed to measure HCN at trace levels in ambient air. There is currently no 

EPA certified method for this determination. The design combines elements of EPA air quality 

measuring guidelines along with NIOSH sampling protocols. The sampler consists of soda lime 

sorbent tubes (SKC part number 226-28) connected to a glass inlet. On the other side of the 

sorbent tubes is a low flow pump controlled by a data logger via a feedback loop with a pressure 

transducer. The flow is regulated by a critical orifice, and ambient meteorological parameters are 

collected to determine the exact volume of gas passed through the sorbent tubes. Data collection 

is in twenty-four hour increments. Upon complete exposure of a sorbent tube, it is sealed and 
Hcn Sampling Plan_V7.Docx 9 

shipped to a certified laboratory for analysis in accordance with NIOSH Method 6010. The 

complete NIOSH Method 6010 is included as Appendix A. 

5.1.10.1 Operating Principle 

As discussed above, the HCN sampling system consists of an open-air inlet, sorbent tubes, and a 

pump which pulls air through the sorbent tubes at a rate of 1 liter per minute. The system is 

designed to hold two or more sorbent tubes, where each tube will collect a 24-hour sample. 

Based on the 1-in-3 day schedule, a site visit to change out the tubes will be required every 5-7 

days (or longer if more than two tubes are designed into the system). The total volume of air 

pulled through each sorbent tube is 1,440 liters. This exceeds the recommended total volume of 

NIOSH Method 6010 but is within the capture volume of the sorbent tube and necessary to reach 

the required limits of detection. 

A data logger turns the pump on and off and controls the solenoid valve according to the 1-in-3 

day schedule. The solenoid valve opens and closes to allow air to pass through a sorbent tube 

only during a run day. The data logger also records ambient barometric pressure and 

temperature to calculate the volume of air passed through the sorbent tube during the run day. 

Flow diagrams of the HCN sampling system, showing the system in static mode, warm-up mode, 

and sampling mode, are provided in Figures 1 through 3. 

Figure 1: HCN Sampling System Flow Diagram - Static Mode 

INLET

SOLENOID VALVE

SORBENT 

TUBE 1

PRESSURE 

TRANSDUCER

PUMP

POWER RELAY

POWER

OUTLET

DATA 

LOGGER

BAROMETRIC

PRESSURE

TEMPERATURE

SORBENT 

TUBE 2

CHECK VALVE

CALIBRATION VALVE
Hcn Sampling Plan_V7.Docx 10 

Figure 2: HCN Sampling System Flow Diagram - Warm-Up Mode 

INLET

SOLENOID VALVE

SORBENT 

TUBE 1

PRESSURE 

TRANSDUCER

PUMP

POWER RELAY

POWER

OUTLET

DATA 

LOGGER

BAROMETRIC

PRESSURE

TEMPERATURE

SORBENT 

TUBE 2

CHECK VALVE

CALIBRATION VALVE
Hcn Sampling Plan_V7.Docx 11 

Figure 3: HCN Sampling System Flow Diagram - Sampling Mode Sorbent Tube 1 

On a run day, at 15 minutes before the sampling commences, the data logger turns the pump on 

and switches the solenoid valve to allow air to flow around the sorbent tubes and through the 

pump. This gives the pump time to warm up and ensures that the air in the inlet is homogenous 

when the sampling begins. To initiate sampling, the data logger switches the solenoid valve to 

allow air to flow through the first sorbent tube and the sampling begins. After 24 hours, the data 

logger closes the solenoid valve, stopping flow to the sorbent tube, and turns the pump off. On 

the next run day, after the warm-up period, to initiate sampling, the data logger switches the 

solenoid valve to allow air flow through the second sorbent tube. After 24 hours, the data logger 

closes the solenoid valve, stopping flow to the second sorbent tube. The tubes are replaced 

before the next run day and the sampling process repeats. 

After the 24-hour sampling is complete, each sorbent tube is sealed and shipped to a certified 

laboratory where the HCN is extracted and analyzed using spectroscopy. One in every five 

sorbent tubes will be a field blank. The blank tubes will follow the same path as the sampled 

tubes, with the exception of being inserted into the sampling system. 

INLET

SOLENOID VALVE

SORBENT 

TUBE 1

PRESSURE 

TRANSDUCER

PUMP

POWER RELAY

POWER

OUTLET

DATA 

LOGGER

BAROMETRIC

PRESSURE

TEMPERATURE

SORBENT 

TUBE 2

CHECK VALVE

CALIBRATION VALVE
Hcn Sampling Plan_V7.Docx 12 

The detection limit for this HCN sampling method is reported to be approximately 0.2 ppb1, 

which is an order of magnitude less than the EPA reference concentration of 2.8 ppb. 

5.1.11 Power and Data Transfer 

Solar power is used to operate the equipment. The data logger is powered separately via a 

smaller solar cell to prevent total data and communications loss during periods of power loss. A 

cellular Internet modem is installed providing real-time satellite communications. 

5.1.12 Meteorological Towers 

A 10-foot Rohn 25G meteorological tower will be installed for the purpose of mounting the 

sensors. The tower will be grounded, and lightning protection will be installed on all signal lines. 

5.2 Rationale for Design 

The equipment has been selected based on its conformity to current EPA standards for 

meteorology and current NIOSH standards for HCN monitoring. 

5.3 Scheduled Measurement Activities 

The sampler pump will be activated on 1-in-3 day schedule. During this period all parameters, 

with the exception of HCN concentration, will be collected every two seconds. This is 

summarized in Table 5 and Table 6. 

Table 5: Sampling Frequency 

Parameters 

Engineering 

Units Sampling Rate Averaging Rate 

Number of 

Samples per 

24-Hour Period 

Wind speed Meters/second Every 2 seconds Every 15 minutes 96 

Wind direction Degrees Every 2 seconds Every 15 minutes 96 

Ambient 

temperature and 

relative humidity 

Degrees 

Celsius and 

percent 

Every 2 seconds Every 15 minutes 96 

Barometric 

pressure 

Millibar Every 2 seconds Every 15 minutes 96 

HCN sampler flow Liters/minute Every 2 Seconds Every 15 minutes 96 

HCN 

concentration* 

Parts per 

billion 

Every 24 hours Every 24 hours 1 

*HCN concentration can only be determined upon completion of laboratory analysis. 

 

1 Kenneth G. Orloff et al., Hydrogen cyanide in ambient air near a gold heap leach field: Measured vs. modeled 

concentrations, Atmospheric Environment, 2006, p. 3023. 
Hcn Sampling Plan_V7.Docx 13 

Table 6: Scheduled Sampling Activities 

Activity Frequency Required Personnel 

Site Check Every 5-7 days Maintenance Technician 

Calibration At installation Project Technician 

Flow Audit At close out Auditor 

5.4 Measurement System Failure Response 

The primary mechanism for ensuring normal system operation will be comprised of on-site 

checks conducted after the tubes have been sampled and before the next run day. The site check 

schedule will be every 5-7 days (or longer if more than two tubes are designed into the system). 

The Maintenance Technician is responsible for on-site checks and completion of Site Check 

Forms. Any issues that are detected during the site checks will be resolved as soon as possible. 

If a run day sampling is missed or incomplete, a substitute 24-hour sampling can be used if it is 

completed before the next scheduled run day. 
Hcn Sampling Plan_V7.Docx 14 

SECTION 6 

SAMPLING METHOD REQUIREMENTS 

6.1 Sample Handling and Custody Requirements 

A new sorbent tube will be inserted into the sampler system prior to midnight of a run day. 

After completion of the run, the sorbent tube will be removed and prepared for shipment to a 

certified lab. All sorbent tubes used for sampling will be tracked in a Chain of Custody Form. 

6.2 Analytical Methods Requirements and Breakthrough Check 

The sample will be digested at the lab and a coloring agent will be added to make the cyanide 

spectroscopically active. UV/Vis spectroscopy will be employed to determine the cyanide 

concentration. The quantity of cyanide present will be combined with the known flow of the 

sample exposure to generate a 24-hour HCN sample concentration. The analysis will be 

conducted in accordance with NIOSH Method 6010 (included as Appendix A). 

As part of the HCN analysis, each tube will be checked for breakthrough. The sorbent tubes 

consist of a front half and back half. Each half will be analyzed separately to determine the mass 

of cyanide. Any sample where the mass of cyanide in the back half is greater than one-tenth of 

the mass of cyanide in the front half will be flagged indicating that breakthrough has occurred. 

6.3 Quality Control Requirements 

Quality control for the program will be affected through the use of site checks, post-installation 

calibration, and close out audits. Information provided by each of these methods is documented 

in the Table 7 below. 
Hcn Sampling Plan_V7.Docx 15 

Table 7: Project Quality Control Checks 

QC Check Information Provided Frequency 

Site Checks All information about the station status, which 

cannot be determined from the raw data. 

Additionally, it provides real-time data for 

comparison with hourly averages to insure 

that station is functioning within prescribed 

guidelines. 

Every 5-7 days 

Calibrations Determines the serviceability, accuracy, and 

precision of the equipment operating on site. 

Sensors are tested over a full range of 

operating conditions to ensure that they are 

performing within prescribed guidelines. 

At installation 

Flow Audit Determines the serviceability, accuracy, and 

precision of the equipment operating on site. 

Sensors are tested over a full range of 

operating conditions to ensure that they are 

performing within prescribed guidelines. 

At close out 
Hcn Sampling Plan_V7.Docx 16 

SECTION 7 

INSTRUMENT/EQUIPMENT TESTING, INSPECTION, AND 

MAINTENANCE REQUIREMENTS 

The sensor/equipment maintenance schedule is based on the manufacturer’s guidelines. All 

routine maintenance tasks will be accomplished by the Project Technician. In addition, 

preventive maintenance tasks are summarized in Table 8. 

Table 8: Preventive Maintenance Schedule 

Parameter Sensor Replacement Frequency 

Wind speed and direction R.M. Young 05305-AQ Every 2 years. 

Temperature/relative humidity Campbell Scientific HMP45C Every 2 years. 

Barometric pressure Vaisala PT101B Every 2 years. 

Sampling pump SKC Low Flow Pump to be refurbished 

annually. 

*Due to the duration of the sampling program, it is anticipated that preventive maintenance will not be needed. 

7.1 General Procedures 

The Project Technician will review the Site Check Forms and compare them to the 15-minute data 

averages to ensure proper system operation and data transfer. 

7.2 Instrument Calibration and Frequency 

The following section outlines the preventive maintenance/recalibration of the equipment used 

to test the performance of the on-site systems. 

7.2.1 Calibration Equipment Maintenance 

The identity, frequency, and governing standard for all calibration equipment can be found in 

Table 9. 
Hcn Sampling Plan_V7.Docx 17 

Table 9: Calibration Equipment Testing 

Parameter 

Calibration 

Equipment 

Calibration 

Frequency Reference 

Wind speed Anemometer Drive 

200 to 15,000 RPM 

Biannually EPA 600/R-94/038D, 

Section 4.2.2 

Wind direction Degree Wheel N/A EPA 600/R-94/038D, 

Section 4.2.2 

Temperature Temperature 

Standard 

Annually EPA 600/R-94/038D, 

Section 4.3.2 

Barometric pressure Altimeter N/A EPA 600/R-94/038D, 

Section 4.6 

Relative humidity Collocated HMP45C Biannually EPA 600/R-94/038D, 

Section 4.6 

Data logger Voltmeter Annually EPA 600/R-94/038D, 

Section 4.1.4.1 

Flow Flow Meter Annually N/A 

The equipment supplier will be required to maintain calibration equipment certifications in hard 

copy. 

7.2.2 Calibration Records and Traceability 

Calibration Forms are completed and maintained by project personnel. All Calibration Forms 

indicate the sensor calibrated, its serial number, the date calibrated, and any other pertinent 

information/anomalies. 
Hcn Sampling Plan_V7.Docx 18 

SECTION 8 

INSPECTION/ACCEPTANCE REQUIREMENTS FOR 

SUPPLIES AND CONSUMABLES 

The only consumable used in this process is the sorbent tubes. All tubes will be inspected upon 

receipt. Any tubes which show signs of physical damage will be discarded. Documentation sent 

with the maintenance items are kept on file as they apply to each sensor and its serial number. 
Hcn Sampling Plan_V7.Docx 19 

SECTION 9 

DATA MANAGEMENT 

The data will be collected and stored in the data logger and backed up in the on-site storage 

module. The data can be automatically or manually transferred to the user’s database. The data 

will then be quality controlled/quality assurance checked (QA/QC’d) and stored on a server. 

9.1 Data Custody 

Data retrieval, quality control, and processing will be documented. Site Check Forms and all 

other program documentation will be archived. Additionally, a journal will be kept to record any 

anomalous occurrences. 
Hcn Sampling Plan_V7.Docx 20 

SECTION 10 

DATA VALIDATION AND USABILITY 

10.1 Data Review, Validation, and Certification 

10.1.1 Data Validation 

The data will be reviewed, quality controlled/quality assurance checked (QA/QC’d), and 

validated in accordance with EPA guidelines. 

10.1.2 Data Collection 

Data received from the site will consist of 15-minute averages for all parameters. A complete list 

of parameters from the site can be found in Table 10. 

Table 10: Data Recorded on Site 

Parameter Units Frequency 

Array ID N/A Every 15 minutes 

Year -- Every 15 minutes 

Day Julian Day Every 15 minutes 

Time Hour/Minute Every 15 minutes 

Wind speed Meters/Second Every 15 minutes 

Wind direction Degrees from Every 15 minutes 

Wind direction standard deviation None Every 15 minutes 

Barometric pressure Millibar Every 15 minutes 

Relative humidity Percent Every 15 minutes 

Ambient temperature Degrees Celsius Every 15 minutes 

Data logger battery voltage DCV Every 15 minutes 

SIN wind direction None Every 15 minutes 

COSINE wind direction None Every 15 minutes 

Flow l/min. Every 15 minutes 

10.1.3 Data Reduction 

On-site data is collected every two seconds and placed into temporary storage. Every 15 minutes 

the data is reduced and stored in the ring memory of the data logger. The wind speed, 

temperature, relative humidity, barometric pressure, and flow data are reduced as scalar 

averages using the equation below. 

= ∑

N

i u

N

u

1

1

The wind direction data is reduced as a unit vector according to the following equations. 
Hcn Sampling Plan_V7.Docx 21 

= ∑

N

S i Sin

N

V

1

1 θ

= ∑

N

C Cos i N

V

1

1 θ

 X

V

V ArcTan

C

S +⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ θ = 

 If Vc < 0 then X = +180 

 If Vs < 0 then X = +360 

 If Vs > 0 then X = +0 

The wind direction deviation is reduced using the Yamartino algorithm found below. 

( ) ( )[ ] 3 σ θ1 = ArcSin ε 1+ 0.1547ε

 where, [ ] (() () ) 2

1

2 2 1 = − VS + VC ε

and Vs and Vc are as defined above. 

After the 15-minute data has been downloaded, it is processed into one-hour averages using the 

same equations listed above. 

10.2 Validation Methods 

10.2.1 Data Review and Validation Requirements 

The data review and validation requirements follow the protocols outlined in Section 5 of this 

monitoring plan. The validation is accomplished by using quality control standards based on 

federal and manufacturer’s guidelines as well as expected sampler performance. If a quality 

control standard is not met, the data will be flagged initially, and the causes immediately 

investigated. All data, which is found to be invalid, will be removed from the data set. All data, 

which is subsequently proven to be valid, will be processed for inclusion in the reports. 
APPENDIX A 

NIOSH Method 6010 
HYDROGEN CYANIDE 6010

HCN MW: 27.03 CAS: 74-90-8 RTECS: MW6825000

METHOD: 6010, Issue 2 EVALUATION: FULL Issue 1: 15 May 1989

Issue 2: 15 August 1994

OSHA : 10 ppm (skin)

NIOSH: STEL 4.7 ppm

ACGIH: C 10 ppm (skin)

(1 ppm = 1.105 mg/m3 @ NTP)

PROPERTIES: gas; BP 26 °C; vapor density 0.93

(air = 1.00); d(liq) 0.69 g/mL @ 20 °C;

 VP 82.7 kPa (620 mm Hg) @ 20 °C;

 explosive range 5 to 40% v/v in air

SYNONYMS: hydrocyanic acid, prussic acid, formonitrile

SAMPLING

SAMPLER: SOLID SORBENT TUBE

(soda lime, 600 mg/200 mg)

FLOW RATE: 0.05 to 0.2 L/min

VOL-MIN: 2 L @ 5 ppm

 -MAX: 90 L

SHIPMENT: routine

SAMPLE 

STABILITY: at least 2 weeks @ 25 °C [1]

BLANKS: 2 to 10 field blanks per set

MEASUREMENT

TECHNIQUE: SPECTROPHOTOMETRY,

VISIBLE ABSORPTION

ANALYTE: cyanide ion complex

DESORPTION: 10 mL deionized water; stand 60 min

COLOR DEVELOPMENT: N-chlorosuccinimide/

succinimide oxidizing agent

and barbituric acid/pyridine

coupling agent; absorption @ 

580 nm in 1-cm cuvette

CALIBRATION: standard solutions of KCN in 0.1 N

NaOH

RANGE: 10 to 300 μg CN- per sample [1]

ESTIMATED LOD: 1 μg CN- per sample [1]

PRECISION (Sr): 0.041 @ 10 to 50 mg per sample [1]

ACCURACY

RANGE STUDIED: 2 to 15 mg/m3 [1]

(3-L samples)

BIAS: Not significant

OVERALL PRECISION (Sˆ

rT): 0.076 [1]

ACCURACY: ± 15.0%

APPLICABILITY: The working range is 0.3 to 235 ppm (3 to 260 mg/m3) for a 3-L air sample. This method is applicable to STEL

measurements. Particulate cyanides are trapped by the initial glass fiber membrane disk. This method is more sensitive and

subject to fewer interferences than NIOSH Method 7904, which uses ion specific electrode analysis. The method was used t o

determine HCN in firefighting environments [2].

INTERFERENCES: A high concentration of hydrogen sulfide gives a negative interference.

OTHER METHODS: This is based on the method of Lambert, et al. [3]. NIOSH Method 7904 uses an ion specific electrode for

measurement. The method has been adapted for use with a Technicon Autoanalyzer [4].

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
HYDROGEN CYANIDE: METHOD 6010, Issue 2, dated 15 August 1994 - Page 2 of 5

SAMPLING:

REAGENTS:

1. Potassium cyanide*, reagent grade.

2. Succinimide, reagent grade.

3. N-Chlorosuccinimide, reagent grade.

4. Barbituric acid, reagent grade.

5. Pyridine, spectrophotometric quality.

6. Phenolphthalein, 1% (w/v) in ethanol or

methanol, reagent grade.

7. Hydrochloric acid, concentrated, reagent

grade.

8. Sodium hydroxide (NaOH), reagent grade.*

9. Sodium lime (CaO + 5-20% NaOH), reagent

grade (Aldrich #26,643-4 or equivalent).

Crush and sieve to 10/35 mesh. Store in

capped container.*

10. Water deionized-distilled.

11. Sodium hydroxide solution, 0.1 N.*

12. Calibration stock solution. 1 mg /mL CN-.

Dissolve 0.125 g KCN in 0.1 N NaOH in a 50-

mL volumetric flask. Dilute to mark with 0.1 N

NaOH. Standardize by titration with standard

AgNO3 solution (see APPENDIX).

13. Hydrochloric acid solution, 0.15 N.

14. N-Chlorosuccinimide/succinimide oxidizing

reagent. Dissolve 10.0 g succinimide in about

200 mL distilled water. Add 1.00 g Nchlorosuccinimide. Stir to dissolve. Adjust

volume to 1 liter with distilled water. Stable 6

months when refrigerated.

15. Barbituric acid/Pyridine reagent. Add about 30

mL distilled water to 6.0 g barbituric acid in a

100-mL Erlenmeyer flask. Slowly add 30 mL

pyridine with stirring. Adjust the volume to

100 mL with water. Stable 2 months when

refrigerated.

EQUIPMENT:

1. Sampler, glass tube, 9 cm long, 7-mm OD,

5-mm ID, with plastic caps, containing two

sections (front = 600 mg; back = 200 mg)

granular soda lime 10/35 mesh, separated and

contained with silanized glass wool plugs, with

a 5-mm diameter glass fiber filter disk placed

before the plug on inlet side. Tubes are

commerically available. (SKC, Inc. 226-28 or

equivalent.)

 2. Spectrophotometer, visible, 580 nm, with

cuvettes, 1-cm light path.

 3. Personal sampling pump, 0.05 to 0.2 L/min,

with flexible connecting tubing.

 4. Pipets, volumetric 0.1-, 0.5-, 1.0-, 2.0-,

10.0-mL.

 5. Vials, glass or plastic, 15-mL with PTFE-lined

caps.

 6. Flasks, volumetric, 25-, 50-, 100-, 1000-mL,

with stoppers.

 7. Pipets, transfer, disposable.

 8. Syringes, 10-μL, readable to 0.1 μL.

 9. Flask, Erlenmeyer, 100-mL.

10. Syringes, 10-mL, polyethylene with luer tip.

11. Filter cassette, with membrane filter, 13-mm

diameter, 0.45-μm pore size, with luer fitting.

* See SPECIAL PRECAUTIONS

 

SPECIAL PRECAUTIONS: HCN gas and cyanide

particulates are highly toxic and may be fatal if

swallowed, inhaled, or absorbed through the skin

[5]. Soda lime and NaOH are very caustic [5].

Use gloves and a fume hood for handling these

chemicals.

1. Calibrate each personal sampling pump

with a representative sampler in line.

2. Break ends of sampler immediately before

sampling. Attach sampler to personal

sampling pump with flexible tubing.

3. Sample at an accurately known flow rate between 0.05 and 0.2 L/min for a total sample size of

0.6 to 90 L.

4. Cap tube. Pack securely for shipment.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
HYDROGEN CYANIDE: METHOD 6010, Issue 2, dated 15 August 1994 - Page 3 of 5

SAMPLE PREPARATION:

5. Score each sampler with a file. Break sampler at score line.

6. Transfer front and back sorbent sections to separate vials. Discard glass wool plugs separating

and retaining sorbent sections.

NOTE: An estimate of particulate cyanide may be obtained by analyzing the initial glass fiber

filter disk as follows; however, no evaluation data are available for particulate cyanides

determined in this manner.

 (i) Transfer the glass wool plug at the tube inlet and the glass fiber filter disk

immediately behind it to a third vial.

 (ii) Add 10.0 mL 0.1 N NaOH to each vial.

(iii) Proceed with step 8.

7. Add 10.0 mL deionized-distilled water to each vial containing a sorbent section. Cap each vial.

8. Allow to stand 60 minutes, with occasional agitation. Transfer to a 10-mL plastic syringe fitted

with an in-line 0.45-μm filter. Collect the filtrate in a clean vial.

CALIBRATION AND QUALITY CONTROL:

 9. Calibrate daily with at least six working standards over the range 1 to 300 μg CN- per sample.

a. Prepare a working standard solution, 1.00 μg /mL.CN-, by diluting 100 μL of calibration stock

solution to 100 mL with 0.1 N NaOH.

 b. Pipet 0.5-, 1.00-, 1.50-, 2.00- and 2.50-mL of the working standard solution into 25-mL

volumetric flasks to make 0.50-, 1.00-, 1.50-, 2.00- and 2.50- μg CN- standards.

 c. Analyze together with field samples and blanks (steps 12 through 19).

d. Prepare calibration graph (absorbance vs. μg CN-).

10. Determine desorption efficiency (DE) at least once for each lot of soda lime used for sampling. 

Prepare at least three tubes at each of five levels plus three media blanks.

a. Remove and discard back sorbent section of a blank sampler.

b. Inject a known amount of calibration stock solution directly onto the soda lime with a

microliter syringe.

c. Cap, and allow to stand overnight.

d. Desorb (steps 5 through 8) and analyze together with working standards and blanks (steps

12 through 19).

e. Prepare a graph of DE vs. μg CN- recovered.

 11. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration

graph and DE graph are in control.

MEASUREMENT:

12. Set spectrophotometer according to manufacturer's recommendations and to conditions on p.

6010-1.

13. Pipet a sample aliquot estimated to contain 0.5 to 2.5 μg CN- into a 25-mL volumetric flask. 

Alternately, to cover an unknown sample concentration range, pipet 0.5-, 1.00-, and 3.00-mL

aliquots into separate 25-mL vol. flasks for each field sample. Larger or smaller aliquots may be

taken, based on prior knowledge of expected analyte level.

14. Pipet 0.5 mL 0.1 N NaOH into a 25-mL volumetric flask for reagent blank.

15. Add one drop phenolphthalein solution to each standard or sample.

NOTE: Add a little deionized-distilled water to increase volume for easier mixing. All solutions

should be alkaline (pink) at this point.

16. Starting with the reagent blank, add dropwise 0.15 N HCl, with mixing, until pink color just

disappears. CAUTION: HCN may be produced. Work in hood. Immediately add 1.0 mL

N-chlorosuccinimide/succinimide oxidizing reagent. Mix and let stand.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
HYDROGEN CYANIDE: METHOD 6010, Issue 2, dated 15 August 1994 - Page 4 of 5

NOTE 1: To avoid possible loss of HCN, add the oxidizing agent before proceeding to the

next sample.

 NOTE 2: Do not prepare more samples than can be analyzed within the 30-minute maximum

time for color development.

 17. After at least 5 min. standing (but not longer than 15 min), starting with the reagent blank, add

1.0-mL barbituric acid-pyridine coupling reagent. Mix.

 18. Adjust sample volume to 25 mL with deionized-distilled water and allow to stand at least 12 min

(but not longer than 30 min) for color development.

 19. Read absorbance at 580 nm in a 1-cm light path cuvette on a spectrophotometer. If sample

absorbance is outside the range of the calibration standards, take an aliquot, re-analyze (steps

12 through 19), and apply the appropriate aliquot factor in calculations.

CALCULATIONS:

20. Calculate the mass, μg, of CN- in aliquot analyzed. Apply the appropriate aliquot factor to

calculate the mass, μg, of CN- in the original 10-mL solution.

21. Determine the mass, μg CN- (corrected for DE), found in the sample front (Wf) and back (Wb)

sorbent sections and in the average media blank front (Bf) and back (Bb) sorbent sections. If

Wb > Wf/10, report breakthrough and possible sample loss.

 22. Calculate concentration, C, of HCN in the air volume sampled, V(L).

where 1.039 = conversion factor, CN- to HCN

EVALUATION OF METHOD:

The method was evaluated by sampling the test atmospheres of HCN generated from a compressed

mixture of HCN in nitrogen [1]. The range of HCN concentration was equivalent to 2 to 15

mg/m3 for a 3-L air sample. Twenty-two samples collected at 0.2 L/min for 15 minutes

indicated overall precision Sˆ

rT of 0.076 with nearly 100% recovery. Breakthrough occurred

after 40 minutes of sampling at the flow rate of 0.2 L/min at an HCN concentration of

148 mg/m3. Sample tubes spiked with solutions of KCN and analyzed after storage, indicated that the

samples of cyanide ions were stable on the tube for at least 2 weeks. Analysis of 22 tubes which were

spiked with KCN standard solutions in the range 10 to 50 μg indicated a recovery of nearly 100% with a

pooled precision of 0.041. Desorption efficiency may be poor below 10 μg CN- [6].

REFERENCES:

[1] Williamson, George. "Method Development Protocol and Backup Data Report on Hydrogen

Cyanide"

Internal NIOSH/MRSB Report, Unpubl. NIOSH (1988).

[2] Williamson, George. "Analysis of Air Samples on Project 166 (Firesmoke) on HCN; Sequence

NIOSH/MRSB-6366A, Unpubl. NIOSH, (1988).

[3] Lambert, J. L., Ramasamy, J., and J. V. Paukstelis, "Stable Reagents for the Colorimetric

Determination of Cyanide by Modified Konig Reactions," Analyt. Chem., 47, 916-918 (1975).

[4] DataChem Laboratories, NIOSH Sequence #6837-K (unpublished, March 21, 1990).

[5] NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, U.S. Department of Health

and Human Services. Publ. (NIOSH) 81-123 (1981), available as stock #PB 83-154609 form NTIS,

Springfield, VA 22161.

[6] DataChem Laboratories, User Check, NIOSH Sequence #6837-J (unpublished, March 19, 1990).

METHOD WRITTEN BY: George Williamson, NIOSH/DPSE.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
HYDROGEN CYANIDE: METHOD 6010, Issue 2, dated 15 August 1994 - Page 5 of 5

APPENDIX: STANDARDIZATION OF CALIBRATION STOCK SOLUTION

Titrate an aliquot of the cyanide standard stock solution (Reagent 12) with standard silver nitrate

(AgNO3) solution. The end point is the first formation of a white precipitate, Ag[Ag(CN) 2]. Calculate the

cyanide concentration with the following equation:

Mc = 52.04 Va (Ma/Vc)

Where Mc = cyanide concentration (mg/mL)

Va = volume (mL) of standard silver nitrate solution

Ma = concentration (moles/L) of standard silver nitrate solution

Vc = volume (mL) of calibration stock solution titrated

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94