AUDITMEMO_080624 1

T E C H N I C A L M E M O R A N D U M 

Meteorological and PM10 Monitoring Performance 

Audits at Winkelman, AZ and Hayden, AZ Air 

Quality Monitoring Stations (ASARCO LLC Hayden 

Plant Site), June 24, 2008 

PREPARED FOR: John Hillenbrand/U.S. EPA

PREPARED BY: Josephine Lee/CH2M HILL

COPIES: Kevin Murdock/CH2M HILL

DATE: June 24, 2008

On June 24, 2008, CH2M HILL conducted performance audits on two air quality monitoring 

stations located at the Winkelman High School in Winkelman, AZ and the Hayden 

Maintenance Center in Hayden, AZ. This audit report details the results for the equipment 

audited. Performance audits were conducted on the following instruments:

Wind Speed (mph)-3 meters

Wind Direction (degrees)-3meters

Ambient Temperature (degrees C)

Barometric Pressure (mm Hg)

Flow Rate (SLPM)

CH2M HILL Monitoring Station Performance Audit 

An independent performance audit was performed by CH2M HILL Air Quality staff 

according to guidance outlined in EPA/600/R-94/038d, Quality Assurance Handbook for Air 

Pollution Measurement Systems, April 1994. The system including individual measurements 

must be within 7 percent of the calibrated instrument measurement. The pass/fail criteria 

for audit results are based on these accuracies.

During each audit, all sensors, cups, vanes, shields, and cables are inspected to determine 

whether any unusual wear has occurred. In addition, systems and procedures are reviewed to 

determine if the station is being operated according to standard operating procedures and with 

sufficient quality assurance and control measures.

The audit was performed using calibration and test instrumentation for onsite sensor 

evaluation including: instruments for determining bearing condition, wind vane orientation, 

wind speed accuracy, wind direction accuracy and linearity, ambient temperature and 

pressure, and flow rate. 
METEOROLOGICAL AND PM10 MONITORING PERFORMANCE AUDITS AT WINKELMAN, AZ AND HAYDEN, AZ AIR QUALITY MONITORING STATIONS (ASARCO LLC 

HAYDEN PLANT SITE), JUNE 24, 2008

AUDITMEMO_080624 2

Audit Results 

Site 1 – Winkelman High School

PM10 Monitor – Thermo Fisher R&P Partisol (S/N 2025B218520601)

At ambient temperature and pressure, the instrument’s internal sensors were compared to NIST 

traceable standards. Temperature was also verified using an ice bath and comparing the sensor 

reading to the NIST traceable standard. Results for temperature and pressure were within tolerances 

as shown in Table 1.

A NIST traceable calibrated flow meter was attached to the inlet of the PM10 monitor. The 

instrument’s flow rate was compared to the standard flow rate. Results were well within tolerances as 

shown in Table 1.

Table 1

PM 10 Instrument Test

Ambient 

Temperature

(

0C) 

Zero 

Temperature 

(

0C) 

Pressure 

(mm Hg)

Flow 

(slpm)

Standard Response 40.2 3.8 703 16.62

Instrument Response 40.2 3.9 702 16.68

% Difference 0.0 2.6 -0.1 0.4

Wind Speed – 3 meters (RM Young 05103, S/N 69483)

A synchronous motor was attached to the wind speed sensor that simulates wind speeds using known 

rpm rotational speeds. The zero response of the sensor was also checked by recording the datalogger 

value with the sensor not spinning (zero RPM). These values are also recorded. The results of this test 

are shown in Table 2.

Table 2

Wind Speed Motor Test 0 rpm 300 rpm 600 rpm 900 rpm

Actual Desired Response (m/sec) 0 1.47 2.94 4.41

Wind Speed Sensor Response 

(m/sec)

0 1.44 3.00 4.44

Difference (m/sec) 0 -0.03 0.06 0.03

Wind speed sensor bearing starting threshold was measured using a torque watch. The measured 

torque was <0.1 gm-cm, which corresponds to a starting threshold of <2.2 mph and indicated 

acceptable condition. The sensor and cups were inspected and found to be in fair condition. The 

bearings sounded worn and it is suggested that they be replaced in the near future. The sensor passed 

all audit tests.
METEOROLOGICAL AND PM10 MONITORING PERFORMANCE AUDITS AT WINKELMAN, AZ AND HAYDEN, AZ AIR QUALITY MONITORING STATIONS (ASARCO LLC 

HAYDEN PLANT SITE), JUNE 24, 2008

AUDITMEMO_080624 3

Wind Direction –3 meters (RM Young 05103, S/N 69483)

The sensor and vane were inspected and found to be in good condition. Linearity of the wind 

direction sensor response was measured by rotating the directional vane in 90 degree increments and 

recording the sensor response. The sensor responded within 5 degrees of the desired direction and 

passed the audit. The cross-arm alignment was checked using a portable transit. Setting the transit to 

the correct declination of 9.5 degrees, it was found that the cross-arm was oriented to 180 degrees.

Site 2 – Hayden Maintenance Center

PM10 Monitor – Thermo Fisher R&P Partisol (S/N 2025B218490601)

At ambient temperature and pressure, the instrument’s internal sensors were compared to NIST 

traceable standards. Temperature was also verified using an ice bath and comparing the sensor 

reading to the NIST traceable standard. Results for temperature and pressure were within tolerances 

as shown in Table 1.

A NIST traceable calibrated flow meter was attached to the inlet of the PM10 monitor. The instrument 

initially failed the leak test. The o-rings were cleaned and the filter replaced and the instrument 

passed the leak check. The instrument’s flow rate was compared to the standard flow rate. Results are 

within tolerances as shown in Table 3.

Table 3

PM 10 Instrument Test

Ambient 

Temperature

(

0C) 

Zero 

Temperature 

(

0C) 

Pressure 

(mm Hg)

Flow 

(slpm)

Standard Response 41.6 1.5 701 16.74

Instrument Response 41.6 1.6 701 16.71

% Difference 0.0 6.7 0.0 -0.2

Wind Speed – 3 meters (RM Young 05103, S/N 69483)

A synchronous motor was attached to the wind speed sensor that simulates wind speeds using known 

rpm rotational speeds. The zero response of the sensor was also checked by recording the datalogger 

value with the sensor not spinning (zero RPM). These values are also recorded. The results of this test 

are shown in Table 4.

Table 4

Wind Speed Motor Test 0 rpm 300 rpm 600 rpm 900 rpm

Actual Desired Response (m/sec) 0 1.47 2.94 4.41

Wind Speed Sensor Response 

(m/sec)

0 1.56 2.97 4.50

Difference (m/sec) 0 0.09 0.03 0.09
METEOROLOGICAL AND PM10 MONITORING PERFORMANCE AUDITS AT WINKELMAN, AZ AND HAYDEN, AZ AIR QUALITY MONITORING STATIONS (ASARCO LLC 

HAYDEN PLANT SITE), JUNE 24, 2008

AUDITMEMO_080624 4

Wind speed sensor bearing starting threshold was measured using a torque watch. The measured 

torque was <0.1 gm-cm, which corresponds to a starting threshold of <2.2 mph and indicated 

acceptable condition. The sensor and cups were inspected and found to be in good condition. The 

sensor therefore passed all audit tests.

Wind Direction –3 meters (RM Young 05103, S/N 69483)

The sensor and vane were inspected and found to be in good condition. Linearity of the wind 

direction sensor response was measured by rotating the directional vane in 90 degree increments and 

recording the sensor response. The sensor responded within 5 degrees of the desired direction and 

passed the audit. 

Summary and Recommendations

Two air quality monitoring stations were audited on June 24, 2008. The audit at Station 1, Winkelman 

High School began at 1310 CDT and was completed at 1413 CDT. The audit at Station 2, Hayden 

Maintenance Center began at 1541 and was completed at 1645. The data collected during audit periods 

should be invalidated from the final data set. 

The auditor reviewed site operating procedures with the site operator regarding bi-weekly visits and data 

downloading procedures. It is recommended that the operators continue to visit the sites every other 

week to perform routine quality assurance checks, confirm proper operation of the instruments, and 

download data from the instruments during these visits. 

Currently there is no procedure for calibration/certification of the flow meter used to perform bi-weekly 

checks. The auditor recommends that the flow meter used to perform these checks be calibrated and

certified by the manufacturer on an annual basis.

The Winkelman High School station meteorological tower is not stable. It was recommended last year 

that this tower be firmly anchored to avoid unbalancing of the meteorological sensors. The RM Young 

meteorological box is not securely attached to the tower, and also requires stabilization (also noted in last 

year’s report). The stabilization of the tower and meteorological box should be addressed. The wind 

speed sensor at this location passed all audit criteria, but the bearings should be replaced to avoid possible 

failure in the future.

Overall, the data currently being collected by both air monitoring stations meet U.S. EPA guidelines and 

can be used for project decisions.