# Meteorological and Hydrogen Cyanide (HCN) Fence Line Monitoring Report

H OMESTAKE 

# M INING 

# C OMPANY OF 

# C ALIFORNIA 

# , B

ARRICK 

# R UBY 

# H ILL 

# M INE

P ROJECT 

### 59-57-4 J ANUARY 

### 2010Rubyhill-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 ANALYSI S ............................................................................................................. ........................................ 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 Hi ghest 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 PlansRubyhill-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, Barr ick Ruby Hill Mine (Ruby Hill) HCN monitor through January 11, 2010. The HCN monitor station be came operational on December 7, 2009, at 1:00 p.m. and the first 24-hour HCN sample was take n on December 9, 2009. The HCN monitoring equipment and sampling proced ures 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 regenerati on, 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 source s 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) tank s, pregnant and barren po nds, 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 barre n tanks at the refinery. A closer view of the refinery area is shown in Figure 3.Rubyhill-Hcn Monitoring Report_R1.Docx 5 

# 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 sa mpling schedule follows a 1-in-3 day calendar and will continue for a total sampling period of three months.

During a run day, all meteorolog ical parameters are collected at two-second intervals and timeaveraged into 15-minute values. Wind speed, wi nd 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, we re 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 fo r 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 paramete rs 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 pr essure parameter was due to a data logger error, which was corrected on December 18, 2009. The data recovery rates at the meteorological station areRubyhill-Hcn Monitoring Report_R1.Docx 6 

### above the recommended rate of 90 percent for ea ch meteorological parameter, except for the barometric pressure.

The data recovery rate for the flow rate through th e sorbent tubes was 91 percent. The data recovery
rate for the HCN concentration from the sorbent tu bes 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, te mperature, relative humidity, and barometric pressure data collected at the station during th e monitored period were processed into hourly averages. Wind speed and wind direction are repo rted for all days during the sample period. Temperature, relative humidity, and barometric pr essure 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 op erated 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 duri ng 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 averag ed 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 seco ndary peak from the west-northwest to the northnortheast. The winds ranged from moderate to br isk this period. A breakdown of the wind speed profile for this period yields the following: Ther e 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 av eraged winds by directio n 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, whic h 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 no rth-northeast with a secondary peak from theRubyhill-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 wind s 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 Averag ed 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 = 739Rubyhill-Hcn Monitoring Report_R1.Docx 11 

# 2.2 Temperature, Relative Humi dity, 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 hour ly 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 sa mpling 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 fo r the period was 606 mmHg and occurred for nine hours in the morning of January 11, 2010. The mini mum 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 592Rubyhill-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 pr essure 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 thr ee 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 samp ling period are summarized in Table 6. For all of the run days, except January 8, 2010, the HCN co ncentration was below the detection level of 0.21 μg/sample. On January 8, 2010, the HCN concentration was 0.16 μg/m 3 

### . 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-de tect 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/m 3



### .Rubyhill-Hcn Monitoring Report_R1.Docx 13 Table 6: HCN Concentration December 9, 2009 - January 11, 2010 (μg/m 3 )



### HCN Concentration

Run Day* Actual Conditions Standard
Conditions 1 

### 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 week s of monitoring, an analys is 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 HC N 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) bl owing 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/m 3 

### ) 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 <0.11Rubyhill-Hcn Monitoring Report_R1.Docx 15 Figure 5: Measured HCN Concentration Analysis



### Figures 6 and 7 summarize the 24-hour wind dire ction (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 concentr ation 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 0.20PercentofWinds(%)HCNConcentration(μg/m3)



### Run Day HCN Concentration Percent of Winds Towards MonitorRubyhill-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 DataDay 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Avg Max Min12/9/2009 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 5.3 4.1 2.3 5.7 0.212/10/2009 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 0.3 0.2 2.0 5.8 0.112/11/2009 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 7.1 8.0 4.8 9.2 0.212/12/2009 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 4.3 6.1 8.2 10.5 4.312/13/2009 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 0.3 1.4 1.9 4.9 0.212/14/2009 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 6.1 7.5 3.1 7.5 0.612/15/2009 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 9.7 7.9 7.2 10.7 0.612/16/2009 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 2.5 3.9 2.6 6.3 0.612/17/2009 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 1.7 3.4 2.2 4.4 0.012/18/2009 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 3.7 3.7 2.4 4.9 0.612/19/2009 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 1.3 1.9 2.1 5.2 0.012/20/2009 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 2.6 3.9 2.6 6.5 0.312/21/2009 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 8.3 8.2 5.3 10.4 1.012/22/2009 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 2.4 2.4 3.3 6.7 0.612/23/2009 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 0.7 1.5 1.8 2.5 0.712/24/2009 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 1.0 2.2 1.4 3.1 0.112/25/2009 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 4.7 5.2 1.9 5.2 0.012/26/2009 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 1.2 1.3 3.2 7.8 0.612/27/2009 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 3.0 1.2 1.6 3.6 0.112/28/2009 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 4.9 1.4 1.8 4.9 0.412/29/2009 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 0.8 4.6 1.5 4.6 0.012/30/2009 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 3.2 4.1 1.9 4.1 0.112/31/2009 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 1.7 4.6 3.7 8.3 0.51/1/2010 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 4.5 2.7 2.1 5.2 0.11/2/2010 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 5.1 4.4 2.7 5.4 0.11/3/2010 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 0.0 0.7 1.4 4.8 0.01/4/2010 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 1.8 3.7 1.5 5.8 0.01/5/2010 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 2.3 2.9 2.0 5.7 0.01/6/2010 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 0.3 0.5 1.7 4.2 0.21/7/2010 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 3.0 2.6 1.2 3.0 0.41/8/2010 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 1.1 1.1 1.2 3.7 0.31/9/2010 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 1.5 0.8 1.1 3.4 0.41/10/2010 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 2.0 1.1 1.2 2.2 0.41/11/2010 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 7.3‐‐4.1 9.4 0.7Avg 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 3.1 3.3 2.6‐‐ ‐‐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 9.7 8.2‐‐10.7‐‐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 0.0 0.2‐‐ ‐‐0.0‐‐IndicateinvaliddataWinddatafromDecember9,2009,throughJanuary6,2010,wereobtainedfromtheRubyHillmeteorologicalstation.SAROADforBarrick,RubyHillChannel:WS_ms_10mMonth:12/09/09‐01/11/10HourofdayDay 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Max Min12/9/2009 242 209 241 232 177 202 175 157 173 37 47 31 3 17 322 27 166 166 165 164 166 165 165 168 322 312/10/2009 169 155 185 157 158 163 170 167 174 45 354 17 28 26 30 155 162 166 165 163 164 182 151 171 354 1712/11/2009 149 293 313 283 312 294 357 300 164 158 153 150 142 148 151 158 156 164 161 152 152 154 163 161 357 14212/12/2009 160 159 156 156 156 160 158 159 156 155 157 152 151 147 157 148 143 138 175 156 169 172 150 202 202 13812/13/2009 309 53 327 360 245 258 228 238 27 274 302 273 261 275 283 286 301 277 0 90 155 238 184 200 360 012/14/2009 192 200 259 68 163 170 165 170 299 27 37 46 354 66 79 123 168 169 167 165 171 178 167 163 354 2712/15/2009 158 159 172 168 156 157 157 156 156 160 163 165 156 160 166 164 159 167 184 43 143 154 155 158 184 4312/16/2009 219 275 235 177 197 158 172 222 288 324 7 24 333 324 295 357 165 158 163 165 165 170 172 164 357 712/17/2009 165 165 162 160 169 178 160 165 250 342 340 7 17 329 343 314 157 170 153 165 168 164 173 165 343 712/18/2009 171 165 164 166 161 155 163 163 132 337 22 4 348 330 307 306 163 165 168 166 165 166 166 167 348 412/19/2009 165 165 166 171 156 163 168 165 308 30 311 15 324 27 0 307 187 145 235 123 163 159 164 165 324 012/20/2009 167 300 229 27 304 140 135 297 359 353 319 309 314 226 158 175 171 182 176 177 173 253 150 165 359 2712/21/2009 191 135 193 187 151 162 162 159 315 138 303 312 311 141 158 162 155 156 156 152 152 148 149 151 315 13512/22/2009 156 349 322 157 310 12 281 303 303 352 360 2 355 329 336 330 327 347 328 323 313 318 320 344 360 212/23/2009 325 327 330 329 306 308 314 318 314 313 331 7 359 334 337 304 310 304 293 286 290 282 293 301 359 712/24/2009 273 273 311 342 283 333 197 171 221 346 24 24 38 24 348 354 161 163 164 167 164 152 173 166 354 2412/25/2009 165 163 155 152 157 155 166 162 172 23 27 335 351 340 20 0 277 194 164 165 167 165 169 163 351 012/26/2009 167 165 166 169 160 265 293 152 133 121 204 166 326 150 159 168 178 199 178 189 183 226 338 314 338 12112/27/2009 296 290 166 161 171 141 175 203 141 5 346 11 329 1 41 134 157 167 178 213 224 161 170 162 346 112/28/2009 169 275 271 301 249 282 170 193 328 346 320 340 4 2 1 176 164 177 335 166 147 153 164 219 346 112/29/2009 233 152 185 335 321 3090 0 0 8 35 326 313 308 320 318 287 166 167 169 179 211 269 153 335 012/30/2009 191 284 257 282 197 169 187 243 299 326 321 309 340 333 310 340 347 351 208 175 307 161 164 166 351 16112/31/2009 166 162 166 165 164 164 184 196 271 5 349 330 309 1 130 160 116 169 97 202 24 179 88 168 349 11/1/2010 190 177 133 185 268 293 73 148 165 204 345 102 248 43 183 154 173 165 188 168 165 172 165 166 345 431/2/2010 167 167 164 169 176 162 166 166 173 312 39 19 60 67 72 207 163 165 165 166 167 167 165 163 312 191/3/2010 167 177 170 168 164 154 169 152 174 326 17 40 42 29 27 331 210 295 302 337 319 272 158 300 337 171/4/2010 1 148 311 76 25 285 80 111 17 27 3 15 17 360 35 4 164 152 164 163 159 169 174 161 360 11/5/2010 184 162 167 159 162 164 174 216 172 150 348 335 29 81 145 57 204 160 167 244 158 163 160 167 348 291/6/2010 167 173 170 161 164 166 167 163 151 353 13 25 19 311 322 188 44 175 167 164 295 15 288 285 353 131/7/2010 358 300 261 321 335 48 49 310 338 309 356 3 8 17 359 174 150 161 168 163 153 152 155 155 359 31/8/2010 154 156 154 156 41 116 143 325 3533 8 7 5 240 244 95 309 161 131 179 216 232 148 169 353 31/9/2010 313 244 173 179 161 137 154 92 2 21 16 14 83 296 16 279 165 158 193 188 167 302 186 321 321 21/10/2010 125 181 157 181 169 171 304 161 82 3 348 17 45 31 3 51 172 170 155 161 156 152 156 148 348 31/11/2010 157 160 153 165 167 248 116 141 309 327 312 340 215 141 148 161 150 145 142 134 147 146 152‐‐340 116Max 358 349 330 360 335 333 357 325 359 353 360 340 359 360 359 357 347 351 335 337 319 318 338 344 360‐‐Min 1 53 133 27 25 12 0 0 0 3 3 2 3 1 0 0 44 138 0 43 24 15 88 148‐‐0‐‐IndicateinvaliddataWinddatafromDecember9,2009,throughJanuary6,2010,wereobtainedfromtheRubyHillmeteorologicalstation.SAROADforBarrick,RubyHillChannel:WD_10mMonth:12/09/09‐01/11/10HourofdayDay 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Avg Max Min12/9/2009‐15.83‐16.10‐15.69‐16.72‐16.91‐16.49‐16.11‐15.97‐12.78‐8.58‐7.34‐6.07‐6.00‐5.30‐5.22‐6.35‐10.03‐13.36‐14.26‐14.00‐13.93‐13.72‐13.00‐12.99‐12.20‐5.22‐16.9112/10/200912/11/200912/12/2009‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐3.08‐2.84‐2.42‐2.01‐1.48‐2.37‐1.48‐3.0812/13/200912/14/200912/15/2009‐2.93‐2.81‐2.83‐2.91‐2.49‐2.56‐2.48‐2.22‐1.81‐1.34‐0.75‐0.57‐0.27‐0.30‐0.59‐0.20‐0.08‐0.08‐0.35‐2.23‐1.39 0.32 0.40 0.45‐1.25 0.45‐2.9312/16/200912/17/200912/18/2009‐‐ ‐‐ ‐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 1.20‐2.17‐2.95‐3.31‐3.96‐4.27‐5.00‐5.31‐0.97 4.98‐5.3112/19/200912/20/200912/21/2009‐2.13‐2.46‐3.30‐3.36‐4.74‐2.30‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐0.63‐0.62 1.34 0.93 0.28‐0.19‐0.42‐0.71‐0.91‐1.28‐1.81‐2.14‐2.10‐1.40 1.34‐4.7412/22/200912/23/200912/24/2009‐11.17‐10.65‐10.87‐11.50‐11.45‐11.71‐12.07‐11.69‐8.55‐5.03‐3.87‐2.73‐2.89‐2.22‐2.26‐3.75‐7.20‐10.25‐10.59‐10.46‐10.39‐9.96‐10.43‐10.21‐8.41‐2.22‐12.0712/25/200912/26/200912/27/2009‐8.83‐9.24‐9.24‐7.54‐8.08‐8.59‐8.93‐9.96‐8.06‐3.12‐3.14‐1.35‐2.04‐1.43‐0.42‐2.93‐4.60‐5.41‐6.10‐7.42‐8.47‐8.61‐8.26‐8.73‐6.27‐0.42‐9.9612/28/200912/29/200912/30/2009‐5.11‐5.23‐5.52‐5.84‐5.78‐5.94‐5.97‐5.40‐4.53‐4.40‐4.08‐4.84‐4.75‐5.13‐5.16‐4.98‐5.65‐6.28‐7.28‐7.59‐8.01‐8.18‐9.80‐10.65‐6.09‐4.08‐10.6512/31/20091/1/20101/2/2010‐3.77‐3.71‐3.34‐2.85‐3.90‐3.97‐4.46‐5.24‐3.02 1.22 3.96 4.06 4.93 4.18 3.69 2.19‐0.33‐2.84‐4.24‐4.70‐5.81‐4.84‐5.20‐5.94‐1.83 4.93‐5.941/3/20101/4/20101/5/2010‐4.89‐5.21‐3.48‐4.27‐5.61‐4.09‐3.36‐4.10‐3.96 0.24 2.30 1.97 3.29 5.61 5.12 4.24 2.19 0.72 0.52 0.45 0.33 0.11‐0.66‐0.64‐0.55 5.61‐5.611/6/20101/7/20101/8/2010‐9.44‐9.50‐8.69‐8.87‐7.96‐9.46‐11.51‐11.81‐10.37‐8.71‐6.45‐4.82‐4.28‐3.31‐2.81‐2.59‐2.84‐3.16‐3.41‐1.39‐1.43‐2.44‐2.63‐1.80‐5.82‐1.39‐11.811/9/20101/10/20101/11/2010‐2.95‐3.53‐3.02‐2.97‐2.40‐2.75‐3.47‐4.05‐0.44 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 1.87 1.78 0.54 3.93‐4.05Avg‐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 0.83‐0.09‐1.69‐3.12‐3.60‐3.59‐4.00‐4.19‐4.69‐4.84‐3.42‐‐ ‐‐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 1.87 1.78‐‐5.61‐‐Min‐11.17‐10.65‐10.87‐11.50‐11.45‐11.71‐12.07‐11.81‐10.37‐8.71‐6.45‐4.84‐4.75‐5.13‐5.16‐4.98‐7.20‐10.25‐10.59‐10.46‐10.39‐9.96‐10.43‐10.65‐‐ ‐‐ ‐12.07‐‐IndicateinvaliddataSAROADforBarrick,RubyHillChannel:T_AMB_CMonth:12/09/09‐01/11/10HourofdayNon‐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‐DayDay 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Avg Max Min12/9/2009 64 63 61 68 68 71 71 72 61 47 43 37 40 37 32 36 50 61 63 61 60 58 57 55 56 72 3212/10/200912/11/200912/12/2009‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐93 93 88 90 93 92 93 8812/13/200912/14/200912/15/2009 66 68 69 68 68 72 73 72 68 66 62 63 60 61 63 59 56 57 55 69 64 50 50 48 63 73 4812/16/200912/17/200912/18/2009‐‐ ‐‐77 77 78 80 80 79 65 57 57 53 51 49 50 55 62 74 77 78 78 79 81 82 69 82 4912/19/200912/20/200912/21/2009 60 63 64 63 68 62‐‐ ‐‐ ‐‐ ‐‐ ‐‐59 58 52 54 57 59 60 62 63 65 68 71 73 62 73 5212/22/200912/23/200912/24/2009 81 78 77 80 79 78 78 75 63 55 52 41 44 45 43 48 57 66 66 65 64 61 62 60 63 81 4112/25/200912/26/200912/27/2009 71 71 69 61 63 64 65 72 63 45 49 45 48 46 42 51 59 59 58 63 72 64 63 66 60 72 4212/28/200912/29/200912/30/2009 87 89 93 97 97 96 97 97 95 96 95 96 95 95 95 95 96 95 95 93 93 92 91 90 94 97 8712/31/20091/1/20101/2/2010 73 73 71 65 71 72 71 73 66 55 49 50 45 43 42 47 54 61 60 57 58 52 52 52 59 73 421/3/20101/4/20101/5/2010 54 55 46 46 51 46 45 49 52 40 38 37 37 30 27 31 37 46 49 50 50 53 57 58 45 58 271/6/20101/7/20101/8/2010 90 90 92 93 89 92 95 94 93 94 88 79 78 74 68 67 68 73 78 61 64 70 65 58 80 95 581/9/20101/10/20101/11/2010 79 80 78 78 75 76 84 85 68 63 61 62 62 55 48 51 57 61 56 48 46 51 55 56 64 85 46Avg 72 73 72 72 73 73 76 77 69 62 59 56 56 54 51 54 60 65 65 67 67 66 66 66 66‐‐ ‐‐Max 90 90 93 97 97 96 97 97 95 96 95 96 95 95 95 95 96 95 95 93 93 92 91 93‐‐97‐‐Min 54 55 46 46 51 46 45 49 52 40 38 37 37 30 27 31 37 46 49 48 46 50 50 48‐‐ ‐‐27‐‐IndicateinvaliddataSAROADforBarrick,RubyHillChannel:RH_percentMonth:12/09/09‐01/11/10HourofdayNon‐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‐DayDay 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Avg Max Min12/9/2009‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐12/10/200912/11/200912/12/2009‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐12/13/200912/14/200912/15/2009‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐12/16/200912/17/200912/18/2009‐‐ ‐‐604 604 604 604 605 605 605 605 605 604 604 604 604 604 604 604 604 604 604 605 605 605 604 605 60412/19/200912/20/200912/21/2009 600 600 600 600 600 599‐‐ ‐‐ ‐‐ ‐‐ ‐‐597 597 596 596 595 595 595 594 594 593 593 593 592 596 600 59212/22/200912/23/200912/24/2009 604 604 604 604 604 604 604 604 604 605 604 604 604 604 604 604 603 604 604 603 603 603 603 603 604 605 60312/25/200912/26/200912/27/2009 600 600 600 600 600 600 600 601 601 601 601 601 601 601 601 602 602 602 602 602 602 602 603 603 601 603 60012/28/200912/29/200912/30/2009 597 597 597 597 597 597 598 598 598 599 599 599 599 599 600 600 601 601 602 602 603 603 603 604 600 604 59712/31/20091/1/20101/2/2010 603 603 603 603 603 604 604 604 604 604 604 604 604 603 603 603 604 604 604 604 604 604 605 605 604 605 6031/3/20101/4/20101/5/2010 604 603 603 603 603 603 603 603 604 604 604 603 603 603 602 602 602 603 603 603 603 603 603 603 603 604 6021/6/20101/7/20101/8/2010 604 604 604 604 604 604 604 604 604 604 604 604 604 603 603 603 604 604 604 604 604 604 605 605 604 605 6031/9/20101/10/20101/11/2010 606 606 606 606 606 605 605 606 606 606 606 605 604 604 604 603 603 603 603 603 603 603 603 602 604 606 602Avg 602 602 602 602 602 602 603 603 603 603 603 602 602 602 602 602 602 602 602 602 602 602 602 602 602‐‐ ‐‐Max 606 606 606 606 606 605 605 606 606 606 606 605 604 604 604 604 604 604 604 604 604 605 605 605‐‐606‐‐Min 597 597 597 597 597 597 598 598 598 599 599 597 597 596 596 595 595 595 594 594 593 593 593 592‐‐ ‐‐592‐‐IndicatesinvaliddataNon‐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‐DaySAROADforBarrick,RubyHillChannel:BP_mmHgMonth:12/09/09‐01/11/10Hourofday

# APPENDIX B 

# HCN DataPage 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 12/31/2009 9365024001 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 595712262009-1 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/6/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 12/26/2009 12/31/2009 9365024002 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 595712262009-2 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/6/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 12/26/2009 12/31/2009 9365024003 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 595712262009-3 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/6/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 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 Laboratorie s, Inc.) 960 W Levoy Drive Salt Lake City, Utah 84123

IHREP-V9.8Page 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 unles s otherwise noted. Samples have not been blank corrected unless otherw ise noted. This test report shall not be reproduced, except in full, without written approval of ALS Laboratory G roup. ALS Laboratory Group is accredited by AIHA for spec ific fields of testing as documented in its current scope of accreditation (ID#101574) which is available on request by contac ting your project manager or view on the internet a t http://www.aiha.org. The quality systems implemented in the laboratory apply to all methods performed by ALS Laboratory Group r egardless of this current scope of accreditation which does not include perfo rmance based methods, modified methods, and methods applied to matrices not listed in the methods. ALS DataChem provides professional analytical servi ces for all samples submitted. ALS Laboratory Grou p is not in a position to interpret the data and assumes no responsibility fo r the quality of the samples submitted.
All quality control samples processed with the samp les in this report yielded acceptable results unles s otherwise noted. 

### General Lab Comments

LOD = Limit of Detection = MDL = Method Detection L imit, A statistical estimate of method/media/instru ment sensitivity. LOQ = Limit of Quantitation = RL = Reporting Limit, A verified value of method/media/instrument sensit ivity. ND = Not Detected, Testing result not detected abov e the LOD or LOQ. ** No result could be reported, see sample comments for details. < This testing result is less than the numerical va lue. ( ) This testing result is between the LOD and LOQ and has higher analytical uncertainty than values a t or above the LOQ. 

### Definitions

IHREP-V9.8Page 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 1/6/2010 1000617001 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 595701032010-1 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/12/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 1/3/2010 1/6/2010 1000617002 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 595701032010-2 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/12/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 1/3/2010 1/6/2010 1000617003 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 595701032010-3 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/12/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 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 Laboratorie s, Inc.) 960 W Levoy Drive Salt Lake City, Utah 84123

IHREP-V9.8Page 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 unles s otherwise noted. Samples have not been blank corrected unless otherw ise noted. This test report shall not be reproduced, except in full, without written approval of ALS Laboratory G roup. ALS Laboratory Group is accredited by AIHA for spec ific fields of testing as documented in its current scope of accreditation (ID#101574) which is available on request by contac ting your project manager or view on the internet a t http://www.aiha.org. The quality systems implemented in the laboratory apply to all methods performed by ALS Laboratory Group r egardless of this current scope of accreditation which does not include perfo rmance based methods, modified methods, and methods applied to matrices not listed in the methods. ALS DataChem provides professional analytical servi ces for all samples submitted. ALS Laboratory Grou p is not in a position to interpret the data and assumes no responsibility fo r the quality of the samples submitted.
All quality control samples processed with the samp les in this report yielded acceptable results unles s otherwise noted. 

### General Lab Comments

LOD = Limit of Detection = MDL = Method Detection L imit, A statistical estimate of method/media/instru ment sensitivity. LOQ = Limit of Quantitation = RL = Reporting Limit, A verified value of method/media/instrument sensit ivity. ND = Not Detected, Testing result not detected abov e the LOD or LOQ. ** No result could be reported, see sample comments for details. < This testing result is less than the numerical va lue. ( ) This testing result is between the LOD and LOQ and has higher analytical uncertainty than values a t or above the LOQ. 

### Definitions

IHREP-V9.8Page 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 1/19/2010 1001934001 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 5957152010-1 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 1/5/2010 1/19/2010 1001934002 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 5957182010-2 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

0.21 NA 0.32 NA Hydrogen Cyanide



### 1/5/2010 1/19/2010 1001934003 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 59571112010-3 Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide



### 1/5/2010 1/19/2010 1001934004 Sample ID: Lab ID: Media: Collected: Received: SKC 226-28, Soda Lime-200/600 Field Blank Sampling Location: Ruby Hill

Method:

Analyte ug/sample mg/m3 ppm 

### NIOSH 6010 Analyzed: 1/19/2010

RL (ug/sample)

0.21 NA <0.21 NA Hydrogen Cyanide

IHREP-V9.8Page 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 Laboratorie s, 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 unles s otherwise noted. Samples have not been blank corrected unless otherw ise noted. This test report shall not be reproduced, except in full, without written approval of ALS Laboratory G roup. ALS Laboratory Group is accredited by AIHA for spec ific fields of testing as documented in its current scope of accreditation (ID#101574) which is available on request by contac ting your project manager or view on the internet a t http://www.aiha.org. The quality systems implemented in the laboratory apply to all methods performed by ALS Laboratory Group r egardless of this current scope of accreditation which does not include perfo rmance based methods, modified methods, and methods applied to matrices not listed in the methods. ALS DataChem provides professional analytical servi ces for all samples submitted. ALS Laboratory Grou p is not in a position to interpret the data and assumes no responsibility fo r the quality of the samples submitted.
All quality control samples processed with the samp les in this report yielded acceptable results unles s otherwise noted. 

### General Lab Comments

LOD = Limit of Detection = MDL = Method Detection L imit, A statistical estimate of method/media/instru ment sensitivity. LOQ = Limit of Quantitation = RL = Reporting Limit, A verified value of method/media/instrument sensit ivity. ND = Not Detected, Testing result not detected abov e the LOD or LOQ. ** No result could be reported, see sample comments for details. < This testing result is less than the numerical va lue. ( ) This testing result is between the LOD and LOQ and has higher analytical uncertainty than values a t or above the LOQ. 

### Definitions

IHREP-V9.8

# APPENDIX C 

# Site Check Forms, Audits, and Calibration

## Calibration Form Ruby Hill A ir 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 A ir 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 A ir 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 A ir 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: 35583F3 SN: 35545F3 Inches Digital
Manometer Raw Inches Sampler 

### 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

H OMESTAKE 

# M INING 

# C OMPANY OF 

# C ALIFORNIA 

# , B

ARRICK 

# R UBY 

# H ILL 

# M INE

P ROJECT 

### 59-51-3 O

CTOBER 

### 2009 U PDATED 

### N OVEMBER 

### 24, 2009ii 

# 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 Plan1 

### 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 oper ations include: ore crushing, heap leaching, carbon adsorption, stripping and regeneration, elec trowinning, retorting, an d 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 ne ar the Ruby Hill operations area.

The HCN monitoring equipment and sa mpling 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 Appe ndix 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 predominan t 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 orde r to identify system design problems, and refine the system configuration and operating and mainte nance 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 amou nt of winds (26 percent combined) from the
west-northwest to the north-northwest. These wi nds 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 nearl y 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 = 83423 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 = 1,9834 

### SECTION 3 

# PROPOSED HCN MONITORING SITE

3.1 Operations Boundary a nd 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 surv ey 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 an d 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 Se ction 2.1, 29 percent of the winds are from the south-southeast and 26 percent of the winds are fr om the west-northwest to the north-northwest.
The west-northwest to the north-northwest winds bl ow directly towards the town of Eureka from the potential HCN sources. Eureka is the larges t 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 me ters north, UTM Zone 11N, NAD83, elevation 6,544 feet.8 

### SECTION 4 

# PROPOSED MODIFICATIONS TO THE GENERAL HCN MONITORING PLAN

Ruby Hill does not propose any modifications to the General HCN Monitori ng 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

N EVADA 

# M INING 

# A SSOCIATION

P ROJECT 

### 59-43-70 O

CTOBER 

### 2009Hcn 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, INSPECTI ON, 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 ................................................................................ ................. 21Hcn 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 6010Hcn 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 develope d 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 System s 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 2Hcn 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 unde r 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 no tes and anomalies, and

• Corrective actions taken (if any). After the first four weeks of sampling, prelim inary 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 an d federal guidelines are strictly defined for meteorology but not for HCN. The equipment se lection 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 pl an submitted by each mine will address the proposed location of the meteorological monito ring 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 Campbe ll Scientific 019ALU Pyranometer mounting arm Campbell Scientific 015ARM Data logger CR3000 Campbell Scientific CR23X or CR10X Power supply with battery Ca mpbell Scientific PS12LA Solar panel Campbell Scientific MSX10R
Wind sensor R.M. Youn g 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 TransducerHcn 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 inst rumentation 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 ex ceed 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 ar chitecture. 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 mo nths of data and will provide a backup of the data and the CR3000 prog ram 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 sens or of the Model 05305 is a helicoid-shaped, fourblade propeller. Rotation of th e 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 platin um 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 radiatio n. 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 HUMICAP TM 

### 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 th e relative humidity sensor is 15 seconds.



## 5.1.9 Barometric Pressure
Barometric pressure is measured every 15 minute s using a Vaisala PT101B sensor. The sensor is mounted inside the data logger enclosure. Barome tric pressure is measured by the data logger using Vaisala’s Barocap silicon capacitive pressu re 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. Th e 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 pass ed through the sorbent tubes. Data collection is in twenty-four hour increments. Upon complete exposure of a sorbent tube, it is sealed andHcn 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 consis ts 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 design ed 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 volu me of the sorbent tube and necessary to reach the required limits of detection.

A data logger turns the pump on and off and cont rols 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 al so 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, show ing 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 VALVEHcn 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 VALVEHcn 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 an d 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 anal yzed using spectroscopy. One in every five
sorbent tubes will be a field bl ank. 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 VALVEHcn Sampling Plan_V7.Docx 12 

### The detection limit for this HCN sampling method is reported to be approximately 0.2 ppb 1



### , 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 commu nications 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 da y 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 gol d 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 Syst em Failure Response
The primary mechanism for ensuring normal sy stem operation will be comprised of on-site checks conducted after the tubes have been sample d 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 Requi rements 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 Me thod 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 cyanid e 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 pr ovided 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 outHcn 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 accomplishe d 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 Campbe ll 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 Chec k Forms and compare them to the 15-minute data averages to ensure proper syst em operation and data transfer. 

# 7.2 Instrument Calibration and Frequency
The following section outlines the preventive ma intenance/recalibration of the equipment used to test the performance of the on-site systems.


## 7.2.1 Calibration Eq uipment 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 Reco rds and Traceability
Calibration Forms are completed and maintained by project personnel. All Calibration Forms indicate the sensor calibrated, its serial numb er, 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 da ta 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 assura nce 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 devi ation 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 pl aced 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

i S 

## Sin N V

1 

## 1 θ



# ∑
= N

i C 

## Cos 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 

## 1547

. 0 1 1 ε ε θ σ + = ArcSin

where, 

# () () 

# ( ) 

# [ ] 2 1 2 2 

## 1 C S 

## V V +

− = 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 invali d, 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/m 3 @ 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 ( S r ): 0.041 @ 10 to 50 mg per sample [1] ACCURACY

RANGE STUDIED: 2 to 15 mg/m 3 [1] (3-L samples)

BIAS: Not significant

OVERALL PRECISION ( S ˆ rT ): 0.076 [1]

ACCURACY: ± 15.0%

APPLICABILITY: The working range is 0.3 to 235 ppm (3 to 260 mg/m 3 ) 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 a nd 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 AgNO 3 

### 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 (W f 

### ) and back (W b 

### ) sorbent sections and in the average media blank front (B f 

### ) and back (B b 

### ) sorbent sections. If W b 

### > W f 

### /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/m 3 

### for a 3-L air sample. Twenty-two samples collected at 0.2 L/min for 15 minutes indicated overall precision S ˆ 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/m 3 

### . 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 (AgNO 3 

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

### ]. Calculate the cyanide concentration with the following equation:

M c 

### = 52.04 V a 

### (M a 

### /V c 

### )

Where M c



### = cyanide concentration (mg/mL) V a 

### = volume (mL) of standard silver nitrate solution M a 

### = concentration (moles/L) of standard silver nitrate solution V c 

### = volume (mL) of calibration stock solution titrated

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