Name: Steve Mills

Title: Designated Representative

Company: Public Service Company of Colorado

Sign Date: 8/31/2010

Name: Patrick Clark

Title: Owner

Company: Airtech Environmental Services

Sign Date: 8/31/2010

Permitted Facility Representative / Date Testing Company Representative / Date

Arapahoe Unit 4 2010 HAP ICR

Final Test Report 

for

/ /

Based on information and belief formed 

after reasonable inquiry, I certify that the 

statements and information in this test 

report are true, accurate, and complete.

I have reviewed all testing details and 

results in this test report and hereby 

certify that the test report is authentic 

and accurate.

Friday, February 18, 2011 Page 1 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Facility Information:

Arapahoe

2601 South Platte River Drive

Denver CO 80223

Contact: Chad Campbell

Phone: 303-294-2111

Fax: 303-294-2859

Email: chad.campbell@xcelenergy.com

Testing Company:

Airtech Environmental Services, Inc.

5776 Lamar Street

Arvada CO 80002

Contact: Patrick Clark

Phone: 303-670-0530

Fax: 303-670-4130

Email: pclark@airtechenv.com

Air Permit Number:

96OPDE136

Permitted Source ID/Name:

4 Unit 4 Boiler

Permitted Maximum Process Rate: Max. Normal Operation Process Rate: Target Process Test Rate

Description of the source (including control equipment). Please see the attachments for source or

 process flow diagram:

Arapahoe Station Unit 4 is a top fired boiler with underfired air. The unit is equipped with a dry sorbent injection 

system (uses Trona) to control SO2 emissions and an FFDC to control PM emissions. The unit typically fires PRB 

subbituminous coal.

The following describes any modifications and/or deviations to the applicable test 

methods. If alternative methods were requested, see the attachments for documentation 

of request AND approval, including dates.

Per discussion with Peter Westlin on January 22, 2010, a three point traverse was approved since there are no 

Industry/SCC/NAIS 221112

Sampling Location Information:

Test Parameter Information:

AFS #: 031.0008.004 FRS #: 110000467129

SCC / Description 10100222 External Combustion Boilers - Electric Generation - Bituminous/Subbituminous 

Coal - Pulverized Coal: Dry Bottom (Subbituminous Coal) 

The following state and federal regulations that apply to the proposed testing:

Location

Round

Duct

Diam.

Distance from 

upstream dist.

Distance from

downstream dist.

Number of

Traverse Ports

Equiv. 

Diam

Min.Travers 

Points

Rect. Duct 

Length /Width

Duct 0 287.5 96 143.9 432 288 1 3

Target

Parameter 

Test

Method

Number of

Test Runs

Test Run

Duration

Sample 

Location Points Comments

Duct Hydrogen Fluoride Method 26A 4 180 0

Duct Hydrogen Chloride Method 26A 4 180 0

Friday, February 18, 2011 Page 2 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

entrained water droplets in the flue gas. Sampling was conducted at a constant rate of 0.75 cfm and utilized the 

Method 26 impingers.

Friday, February 18, 2011 Page 3 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Friday, February 18, 2011 Page 4 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Sampling / Stack Data Results Summary

Location Duct - Method 26A

Average

Run Number 1 2 3

Test Date 6/17/2010 6/17/2010 7/22/2010

Run Start Time 9:40:00 AM 1:12:00 PM 9:55:00 AM

Run Finish Time 12:43:00 PM 4:15:00 PM 1:08:00 PM

Net Run Time, minutes

Dry Gas Meter Volume Sampled, dscf 106.121 105.131 105.170 105.474

Moisture Content of Stack Gas, % 11.54 11.84 13.29 12.223

Moisture Saturation at Stack Gas Temperature, % 100.00 100.00 100.00 100.000

Carbon Dioxide, % 12.1 11.9 12.4 12.133

Oxygen, % 5.9 6.2 6.9 6.333

Average Stack Gas Temperature, °F 321.56 324.11 323.56 323.077

Dry Volumetric Flow Rate, dry scfm 254,070.7 251,371.6 228,019.1 244,487.133

Actual Wet Volumetric Flue Gas Flow Rate, acfm 515,200.9 513,130.9 474,835.8 501,055.867

Percent Isokinetic of Sampling Rate, %

F-Factor, dscfm/MMBtu @ %O2 9574 9622 9644 9,613.333

Fw 0 0 0 0.000

Fc 0 0 0 0.000

Location Duct - Method 26A 3

Average

Run Number

Test Date

Run Start Time

Run Finish Time

Net Run Time, minutes

Dry Gas Meter Volume Sampled, dscf

Moisture Content of Stack Gas, %

Moisture Saturation at Stack Gas Temperature, %

Carbon Dioxide, %

Oxygen, %

Average Stack Gas Temperature, °F

Dry Volumetric Flow Rate, dry scfm

Actual Wet Volumetric Flue Gas Flow Rate, acfm

Percent Isokinetic of Sampling Rate, %

F-Factor, dscfm/MMBtu @ %O2

Fw

Fc

Friday, February 18, 2011 Page 5 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Friday, February 18, 2011 Page 6 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Emissions Summary

Process Run Data

Location: Duct - Method 26A

Compound: Hydrogen Chloride

Average

RunNumber 1 2 3

Mass_mg 80.77 5.256 1.027 29.018

lb/mmBtuO2 2.24E-02 1.51E-03 3.10E-04 0.008

Compound: Hydrogen Fluoride

Average

RunNumber 1 2 3

Mass_mg 1.253 3.166 1.917 2.112

lb/mmBtuO2 3.47E-04 9.08E-04 5.79E-04 0.001

Location: Duct - Method 26A 3

Compound: Hydrogen Chloride

Average

RunNumber 4

Mass_mg 1.4605 1.461

lb/mmBtuO2 3.99E-04 0.000

Compound: Hydrogen Fluoride

Average

RunNumber 4

Mass_mg 2.362 2.362

lb/mmBtuO2 6.46E-04 0.001

Friday, February 18, 2011 Page 7 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Process Run Data

APCD Run Data

Process Lab Run Data

Run Name Value UOM Comments

Target

Value

1 Gross Load 110.71 MW 0

1 Heat Input 1400 MMBTU/HR 0

1 Main Steam Flow 898.89 KPPH 0

1 Flue Gas Flow Rate 21013 KWSCFH 0

1 DSI Injection Rate 45 % 0

2 Gross Load 110.22 MW 0

2 Heat Input 1397.8 MMBTU/HR 0

2 Main Steam Flow 899.29 KPPH 0

2 Flue Gas Flow Rate 20813 KWSCFH 0

2 DSI Injection Rate 45 % 0

3 Gross Load 104.99 MW 0

3 Heat Input 1357 MMBTU/HR 0

3 Main Steam Flow 860 KPPH 0

3 Flue Gas Flow Rate 19737 KWSCFH 0

3 DSI Injection Rate 20 % 0

1 Heat Input Million Btus/million BTU using CO2 1400 0

4 Gross Load 104.82 MW 0

4 Heat Input 1349.0 MMBTU/HR 0

4 Main Steam Flow 860 KPPH 0

4 Flue Gas Flow Rate 19728 KWSCFH 0

4 DSI Injection Rate 20 % 0

4 Heat Input Million Btus/million BTU using CO2 1349.0 0

Run Name Value UOM Comments

Target

Value

1 OVERFIRE AIR 0 0

1 DRY SORBENT INJECTION 0 0

1 BAGHOUSE 0 0

Friday, February 18, 2011 Page 8 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Sampling / Stack Data Results Detail

Location Duct - Method 26A

Average

Run Number 1 2 3

Test Date 6/17/2010 6/17/2010 7/22/2010

Run Start Time 9:40:00 AM 1:12:00 PM 9:55:00 AM

Run Finish Time 12:43:00 PM 4:15:00 PM 1:08:00 PM

Net Traversing Points 18 18 18

Net Run Time, minutes

Nozzle Diameter, inches

Pitot Tube Coefficient 0.84 0.84 0.84 0.840

Dry Gas Meter Calibration Factor 1.0045 1.0045 1.0018 1.004

Barometric Pressure, inches of Mercury 24.6 24.6 24.5 24.567

Average Orifice Meter Differential, inches H2O 1.40 1.40 1.43 1.410

Dry Gas Meter Volume Sampled, cubic feet 135.000 135.000 135.360 135.120

Average Dry Gas Meter Temperature, °F 97.06 102.31 99.86 99.743

Dry Gas Meter Volume Sampled, dscf 106.121 105.131 105.170 105.474

Total Moisture Liquid collected, g 294 300 342.4 312.133

Volume of Water Vapor, standard cubic feet 13.84 14.12 16.12 14.693

Moisture Content of Stack Gas, % 11.54 11.84 13.29 12.223

Moisture Saturation at Stack Gas Temperature, % 100.00 100.00 100.00 100.000

Dry Mole Fraction 0.8846 0.8816 0.8671 0.878

Carbon Dioxide, % 12.1 11.9 12.4 12.133

Oxygen, % 5.9 6.2 6.9 6.333

Carbon Monoxide & Nitrogen, % 82 81.9 80.7 81.533

Fuel Factor 1.24 1.24 1.13

Dry Molecular Weight, lb/lb-Mole 30.17 30.15 30.26 30.193

Wet Molecular weight, lb/lb-Mole 28.77 28.71 28.63 28.703

Flue Gas Static Pressure, inches of H2O 1.2 1.2 1.2 1.200

Absolute Flue Gas Pressure, inches of Mercury 24.69 24.69 24.59 24.657

Average Stack Gas Temperature, °F 321.56 324.11 323.56 323.077

Average Velocity Head, inches of H2O 0.3537134945

6549

0.348940049

25354

0.297037882

951681

0.333

Average Stack Gas Velocity, feet/second 44.80 44.62 41.29 43.570

Stack Cross-Sectional Area, square feet 191.667 191.667 191.667 191.667

Dry Volumetric Flow Rate, dry scfm 254,070.7 251,371.6 228,019.1 244,487.133

Actual Wet Volumetric Flue Gas Flow Rate, acfm 515,200.9 513,130.9 474,835.8 501,055.867

Percent Isokinetic of Sampling Rate, %

Percent Excess Air, % 37.5 40.2 47.9 41.867

F-Factor, dscfm/MMBtu @ %O2 9574 9622 9644 9,613.333

Round Duct Diameter, inches 0 0 0

Rectangular Duct Width, inches 96 96 96

Rectangular Duct Length, inches 287.5 287.5 287.5

Fw 0 0 0 0.000

Fc 0 0 0 0.000

Friday, February 18, 2011 Page 9 of 9
Arapahoe Unit 4 2010 HAP ICR

8/31/2010

Location Duct - Method 26A 3

Average

Run Number

Test Date

Run Start Time

Run Finish Time

Net Traversing Points

Net Run Time, minutes

Nozzle Diameter, inches

Pitot Tube Coefficient

Dry Gas Meter Calibration Factor

Barometric Pressure, inches of Mercury

Average Orifice Meter Differential, inches H2O

Dry Gas Meter Volume Sampled, cubic feet

Average Dry Gas Meter Temperature, °F

Dry Gas Meter Volume Sampled, dscf

Total Moisture Liquid collected, g

Volume of Water Vapor, standard cubic feet

Moisture Content of Stack Gas, %

Moisture Saturation at Stack Gas Temperature, %

Dry Mole Fraction

Carbon Dioxide, %

Oxygen, %

Carbon Monoxide & Nitrogen, %

Fuel Factor

Dry Molecular Weight, lb/lb-Mole

Wet Molecular weight, lb/lb-Mole

Flue Gas Static Pressure, inches of H2O

Absolute Flue Gas Pressure, inches of Mercury

Average Stack Gas Temperature, °F

Average Velocity Head, inches of H2O

Average Stack Gas Velocity, feet/second

Stack Cross-Sectional Area, square feet

Dry Volumetric Flow Rate, dry scfm

Actual Wet Volumetric Flue Gas Flow Rate, acfm

Percent Isokinetic of Sampling Rate, %

Percent Excess Air, %

F-Factor, dscfm/MMBtu @ %O2

Round Duct Diameter, inches

Rectangular Duct Width, inches

Rectangular Duct Length, inches

Fw

Fc

Friday, February 18, 2011 Page 10 of 9