**VIA E**

**- MAIL:**  schrock.bill@ e pa.gov

May 3

, 2012

M r. Bill Schrock

U.S. Environmental Protection Agency 109 T.W. Alexander Drive (E143

- 03) Research Triangle Park, NC 27709

RE: Docket ID No. EPA

– HQ

– OAR

– 2007

- 0544, National Emission Standards for Hazardous Air Pollutants From the Pulp and Paper Industry (76 Federal Register 881328, December 27, 2011)

– Revisions to Residual Risk

Assessment Data for the Port Townsend Mill

De ar M r. Schrock :

Port Town send Paper Corporation (PTPC) owns and operates a Kraft pulp and paper mill locate d in Port Townsend, Washington (Port Townsend Mill). The US Environmental Protection Agency ( EPA ) conducted

residual risk assessment modeling of the Port Townsend Mill (as well as all other major source mills) as p art of the Risk and Technology R eview for the National Emission Standards for Hazardous Air Pollutants From the Pulp and Paper Industry ( Pulp and Paper NESHAP)

. Several environmental groups have used the results of EPA’s risk assessment to argue that EPA should require greater reductions in emis sions through the Pulp and Paper NESHAP rulemaking, even though EPA’s residual risk assessment concluded that the modeled risk was acceptable. For this reason, it remains critical that EPA’s risk modeling is as accurate as possible. To this end,

PTPC rev iewed the input parameters used by EPA for modeling residual risk from the Port Townsend Mill and identified several parameters that require revision. The purpose of this letter is to provide updated information specific to the evaluation of modeled risk from the Port Townsend Mill in the form of the National Emissions Inventory (NEI) data revisions provided in Attachment 1 and to provide supporting information to document

the revisions.

The revisions described in this letter are provided to more accura tely characterize the emission sources at the

Port Townsend mill and are expected to decrease the modeled risk compared to the EPA October 2011 risk modeling results , as summarized in Section 5. This letter presents the NEI data revisions in three parts : updates to source parameters, source locations, and emission rates. The letter also addresses the appropri ateness of meteorological data and, la stly, summarizes risk modeling results based on the attached revisions

.



### 1. SOURCE PARAMETERS

EPA’s r esidual risk m odeling was conducted using an updated version of the EPA Human Exposure Model (HEM)

not available to the public

. Therefore, Trinity Consultants (Trinity) conducted modeling using the publically

available version, HEM

- 3. HEM

- 3 requires two input files to characterize emission sources in the model. The

first is a source location input file, which lists s ource parameter s for modeled emission sources, including one record for each individual source to be modeled. This source location input file provides th e location, size, height, and configuration of each source. The following sub

- sections describe the r evis ions made to source parameters at the mill

.Port Townsend Paper Corporation

- Page 2 May 3 , 2012

Aerated Stabilization Basin ( ASB Pond ) Emissions from the ASB Pond were modeled using the U.S. EPA Wastewater Model, WATER9. As indicated by the WATER9 model, the vast majority of the air emissions emanate from the inlet zone. Additionally, the mill’s

2010 sampling required by the clean conde nsate alternative provisions

, supports this model result, because three of the four quarters of test data show that the concentration of m ethanol decreases by over 99% in the

first zone. As such, the modeled length and width of the basin have been revised to better characterize the

dimensions of the ASB Pond. The revised X and Y length of the ASB pond volume source are 350 feet and 230
feet , respectively.

Additionall y, it should be not ed that modeling using an area source type likely over predict s the modeled concentrations from the ASB pond and thus, modeled risk. The inlet zone of the ASB Pond is at a temperature of approximately 110 ° Fahrenheit, resulting in thermal plume rise, and the aerators and air flow from the fine

bubble diffusers in this area also cause mechanical plume rise. PTPC has observed this plume rise from the inlet

zone of the ASB Pond during monitoring (i.e., the plume rise s above the pond due to these thermal buoy ancy and

mechanical lift effects). HEM

- 3 does not consider this thermal or mechanical plume rise effect from area

sources , and instead assumes modest dispers ion only due to meteorological effects . T herefore, t his assumption
results in over prediction of the risk impact s from the ASB Pond.

Recovery Furnace
The re vised stack diameter of the Recovery Furnace is 7 feet , resulting in an associated revised exit velocity of

80.2 feet per second

. The previously reported diameter was based on the location wher e source tests are conducted, rather than at the exit to the atmosphere.



### 2. SOURCE LOCATIONS

Aeration Stabilization Basin (ASB Pond) The source location input file also provides source loc ation s for modeled emission sources

. Section 1 describes

the revisions made to the X and Y length of the volume source representing the ASB pond. The location of the southwest corner of the source is also updated to reflect the inlet zone, where nearly all of the air emissions emanate from the ASB pond.

Stack Locations

In 2007, PTPC measured source locations with a GPS system. PTPC measured source location again in 2009, this time using Google Map coordinates, which vary slightly from the GPS system. The coordinates of the Lime Kiln, Power Boiler 10, Recovery Furnace, an d Smelt Dissolving Tank are update d to reflect the Google Map coordinate
system

. It appears that EPA’s modeling us ed the same location for multiple stacks. Table 1 present the revised

source locations used in the revised model.Port Townsend Paper Corporation

- Page 3 May 3 , 2012

**Table 1. Revised**  **Emission Source Locations**

**Emission ID Emission Source**  **Latitude** (° N **) Longitude**  **(** ° W **)**
M_WK0007 ASB Pond 48.095383

- 122.804596
W_LK0004 Lime Kiln 48.093569

- 122.797946 W_IC0005, W_IC0006 Power Boiler 10 48.093501

- 122.797596

W_ND0001

, W_ND0002 Recovery Furnace 48.093426

- 122.796841

W_SK0003 Smelt Dissolving Tank 48.093781

- 122.797371



### 3. EMISSION RATES

The second input file required by HEM

- 3 is the emissions input file, which lists e mission rates for modeled

emission sources

. The emissions file contains one record for each combination of emission source and pollutant

. The ASB pond emission rate of acetaldehyde is revised based on mill data from 2010 and 2011 and process improvements. Lime Kiln, Power Boiler 10, and Smelt Di ssolving Tank emission rates for some pollutants are revised to reflect the median emission factor in applicable data sets in the National Council for Air and Stream Improvement (NCASI) Technical Bulletin (TB) No. 973. Only emission factors from these sources for pollutants that contributed significantly to the maximum cancer impact are included in the revision. It is likely that other emission rates from other sources and pollutants may also be better represented by the median of the data set;
howev er , due to time constraints, this review is limited to the pollutants discussed below.

Toxic air pollutant emission rates from the Lime Kiln, Power Boiler 10, and Smelt Dissolving Tank are revised based on NCASI guidance for selecting representative average emission factors. NCASI recognizes a shortcoming of the Kaplan

- Meier (K

- M) estimatio n method used throughout TB No. 973, namely that for data sets with very few detects, the mean and median using the K

- M method may differ quite widely, with the median being significantly lower than the mean. As such, NCASI reanalyzed all data sets with a mean to median ratio of greater than 5.0 to estimate a more realistic median value. Thus, the median reported in TB No. 973 for data sets with very few detects does not require further analysis and may be considered a representative emission

factor.

A s a general rule of thumb, NCASI recommends that the median be selected over the mean when the data set is

non

- normal or skewed and large. 1 The selection of the median over the mean in such cases ensures that the population average is not unduly affected by one or two extreme high data values

. 2

PTPC has reviewed applicable data sets in NCASI TB No. 973 for pollutants presented in this letter and has determined that the median represents better the population average. Most of t hese data sets are determin ed to

be non

- normal, because the upper prediction limit is greater than the mean plus 1.645 of the standard

1 NCASI TB No. 973. Compilation of ‘Air Toxic’ and Total Hydrocarbon Emissions Data for Pulp and Paper Mill Sources

– A Second Update , Section 11.0, Page 200. February 2010.

2 Each of the emission factors in Table 2, Table 3, and Table 4, revised to be based on the median of the data set, have
been d etermined to be based on a non

- normal or skewed data set.Port Townsend Paper Corporation

- Page 4 May 3 , 2012

deviation. 3 For the two data sets that do not meet this general test (cadmium from lime kilns and arsenic from power boilers) , these data sets are also determined to be skewed, because they contain one extreme value that is over twenty times larger than the mean of the other source tests , which skews the population mean. Additionally, the majority of the data sets are de termined to be considered la rge; where the data sets could not clearly be considered large, a review of the data showed that these data sets also included one or two extreme values that unduly affect the mean.

The following sub

- sections identify applicable data sets and their associ ated medium datum point for each emission unit, and provide further explanation for other revisions.

Aerated Stabilization Basin ( ASB Pond ) The revised acetaldehyde emission rate of 6.3 tons per year from the ASB Pond is based on the average of the 2010 and 2011 sampling results and the 23.9 percent volatilization rate of acetaldehyde determined from WATER9 modeling. As determined based on th e past five years of data for ASB influent, and on process improvements associated with the ASB pond and the mill , the two most recent years are more representative of

current and future operation than the 2009 emission rate reported previously

.

Lime Ki ln

Table 2 presents the revised emission factors for the Lime Kiln , which are set to the median emission factor in

NCASI TB No. 973 Table 4.25 and 4.27

. 4 Emission factors are revised based on the review described in Section 3
of this letter

.

**Table 2** 

**. Re**  **vised Lime Kiln Emission Factors**

Pollutant Revised Emission Factor a (lb/T CaO) Revised Emissions (tpy) Acetaldehyde b 6.42E

- 03 0.18 Arsenic compounds 2.80E

- 06 0.00010 Cadmium compounds b 5.81E

- 06 0.00019 Naphthalene 4.62E

- 04 0.013 Nickel compounds b 8.62E

- 05 0.0028

a The revised emission factor is the median of the data set for that pollutant, as presented in NCASI TB No. 973, Table

4.25 or Table 4.27.

b Large data set.

3 NCASI TB No. 973, page 201, states “ if the UPL is greater than the mean plus 1.645 * SD (standard deviation), then it may be assumed that the data set was found to be non

- normal.” The cadmium da ta set from lime kilns and the arsenic data set from power boilers do not meet this general test, but these data sets are also determined to be skewed based on containing one extreme high.

4 NCASI Technical Bulletin No. 973, Compilation of ‘Air Toxic’ and Total Hydrocarbon Emissions Data for Pulp and Paper
Mill Sources

– A Second Update . February 2010. Table 4.25, Summary of Non

- Metal Air Toxic Emissions from Kraft Lime Kilns (in lb/T CaO) , provides non

- metal air toxic emission factors from Kraft lime kil ns. Table 4.27, Summary of Trace Metal Emissions from Kraft Lime Kilns with Wet Scrubbers (lb/T CaO) , provides metal emission factors from lime kilns at Kraft plants.Port Townsend Paper Corporation

- Page 5 May 3 , 2012

Power Boiler 10

Table 3 presents the revised emission factors for Power Boiler 10 , which are set to the median emission factor in

NCASI TB No. 973 Table 7.2. 5 Emission factors are revised based on the review described in Section 3 of this

letter.

**Table 3** 

**. Revised Power Boiler 10 Emission Factors** 

Pollutant a Revised Emission Factor (lb/10 6 Btu) Revised Emissions (tpy) Arsenic compounds b 1.84E

- 06 0.002 2 Beryllium compounds 3.41E

- 07 0.00083 Cadmium compounds b 1.85E

- 06 0.0019

a The revised emission factor is the median of the data set for that pollutant, as presented in NCASI TB No. 973, Table

7.2

.

b Large data set.

Smelt Dissolving Tank

The emission factor s for organic compounds are set to zero to reflect the use of fresh wa ter in the recausticizing area, including the Smelt Dissolving Tank scrubber

. According to the NCASI SARA handbook, t he emission factors for organic compounds apply only to those smelt dissolving tanks that do not use fresh water for mud washing. The Por t Townsend Mill uses fresh water exclusively in the Smelt Dissolving Tank scrubber, and primarily in the mud washer. 6 T hus, the organic emission factors in NCASI TB No. 973 are not applicable.

According to NCASI guidance in TB N o. 973 discussed in Section 3 of this letter , the median of the arsenic data set, as presented in NCASI TB No. 973 Table 4.29 , is representative of the population average

. 7 Table 4 present s the revised emission factors for the Smelt Dissolving Tank

.

5 Table 7.1 in NCASI TB No. 973, Summary of Air Toxic Emissions from Wood

- fired Boilers (lb/10 6 Btu ) , provides non

metal air toxic emission factors from wood

- fired boilers. Table 7.2, Summary of Trace Metal Emissions from Wood

fired Boilers (lb/10 6 Btu ) , provides metal emission factors from wood

- fired boilers.

6 Evaporation condensate is rarely used for mud washing.

7 Table 4.29, Summary of Trace Metal Emissions from Kraft Smelt Dissolving Tanks (lb/T BLS ) , provides metal air toxic emission factors from Kraft Smelt Dissolving Tanks.Port Townsend Paper Corporation

- Page 6 May 3 , 2012

**Table 4**  **. Revis ed Smelt**  **Dissolving Tank Emission Factors**

Pollutant Revised Emission Factor (lb/T BLS) Revised Emissions (tpy) Acetaldehyde b 0 0

Acrolein b 0 0 Arsenic compounds a 9.41E

- 07 0.00019

Benzene b 0 0

Cresols b 0 0 Formaldehyde b 0 0

Methanol b 0 0 Naphthalene b 0 0

Phenol b 0 0

POM 71002 b 0 0 Propionaldehyde b 0 0

a The revised emission factor is the median of the data set for that pollutant, as presented in NCASI TB No. 973, Table

4.29

. The arsenic data set is determined to be a large, n on

- normal data set.

b The emission factor s for organic compounds are set to zero.



### 4. METEOROLOGICAL DATA

HEM

- 3 includes a library of preprocessed meteorological data from the National Weather Service (NWS) observation stations, though user

- specific meteorological data may also be used. One year of surface data is obtained from the meteorological station at t he Seattle

- Tacoma International Airport (station ID 24233) for 1991. Upper air data is obtained from the Quillayute upper air station (upper air ID 94240) for 1991.

The Port Townsend Mill is located on the Olympic Peninsula near the Puget Sound. Becau se of the location’s proximity to the Olympic Mountains , Puget Sound, and other bodies of water, the Port Townsend area is subject

to microclimate effects . Additionally, the mill is located in an area of complex terrain with a substantial body of

water be tween the mil l and the Seattle

- Tacoma International Airport . Therefore, the regional airport used in the HEM modeling conducted by EPA is not representative of the Port Townsend Mill and may result in over prediction of modeled results from the mill. Mor e representative good quality meteorological data are available

from the Port Townsend station (WMO ID 994025). 8



### 5. SUMMARY OF MODELING RESULTS

This section presents the results of revised HEM

- 3 risk assessment modeling conducted for the Port Townsend

Mill by Trinity

. The model input parameters were revised from the EPA model only as described in the preceding sections. This analysis also includes a “base case” model, which consists of the inputs used in EPA’s

m odel, but that is re

- run using the publicly ava ilable version of HEM

- 3 (the EPA model was run using a different version of HEM) . The base case model is run because the results of the revised model are not directly comparable to the results of the EPA model. This section compares the results of the re vised model to the base

case model

.

8 The Port Townsend station is less than three miles from the mill and is also located near the Port Townsend Bay coastline. The wind and temperature data are good quality and complete; however, the station does not include cloud cover data. Cloud cover data could be supplemented f rom nearby stations such as Whidbey Islands (KNUW) or Everett (KPAE), which are both closer to the mill than the Seattle

- Tacoma International Airport.Port Townsend Paper Corporation

- Page 7 May 3 , 2012

Table 5 pr esents the maximum individual cancer risk ( MIR ) percentage decrease from the base case for the

th ree worst

- case receptors for the base case model and the three worst

- case receptors for the revised model

. The table is ordered by base case rank; that is, the worst

- case receptor for the base is presented first, followed by the second worst

- case receptor, and so on.

**Table 5**  **. R esults of HEM Modeling** 

**Location Base Case Rank**  **Revised Rank Percentage**  **Decrease**
**From Base Case a** 

A 1 1 7 74%

B 2 1 31%

C 3 1 3 60%

D 5 2 29%

E 7 3 25%

a The percent age decrease represents the decrease between the revised scenario and the base case model.

Based on Trinity’s best efforts to simulate the HEM modeling used by EPA, it is evident that using the revised information provided would result in a reduced risk. Our client, PTPC requests that EPA update the residual risk

assessment to include the attac hed revisions in order to obtain model results that are more representative of current and future operations at the Port Townsend Mill. If you have any questions or comments about the information presented in this letter , please do not hesitate to contact me at ( 253 ) 867

- 5600 or Val DeLeo (PTPC)

at (360) 379

- 2082

.

Sincerely,

TRINITY CONSULTANTS

Anna Henolson, P.E.

Senior ConsultantPort Townsend Paper Corporation

- Page 8 May 3 , 2012



## ATTACHMENT 1

NEI Data Revisions (Electronic file: mact_1626

- 1_facility_NEI42357.xls)