13776 Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules

1One Hg CEMS vendor was unable to participate.

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 60, 63, 260, 261, 264, 265,

266, 270 and 271

[FRL–5711–5]

Hazardous Waste Combustors;

Continuous Emissions Monitoring

Systems; Proposed Rule—Notice of

Data Availability and Request for

Comments

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Notice of data availability and

request for comments.

SUMMARY: This announcement is a

notice of availability and invitation for

comment on the following reports

pertaining to the proposed requirement

for continuous emissions monitoring

systems for hazardous waste combustors

(61 FR 17358 (April 19, 1996)): Sitespecific Quality Assurance Test Plan:

Method 301 Validation of a Proposed

Method 101B for Mercury Speciation,

with Appendices, dated September 27,

1996; Site-specific Quality Assurance

Test Plan: Total Mercury CEMS

Demonstration, Volumes 1 and 2, dated

October 11, 1996; Site-specific Quality

Assurance Test Plan: Particulate Matter

CEMS Demonstration, Volume 1, dated

August 7, 1996; and Status Report IV:

Particulate Matter CEMS

Demonstration, Volumes 1, 2, and 3,

dated February 12, 1997.

Readers should note that only

comments about new information

discussed in this notice will be

considered. Issues related to the April

19, 1996, proposed rule and subsequent

notices that are not directly affected by

the documents or data referenced in this

Notice of Data Availability are not open

for further comment.

DATES: Written comments on these

documents and this Notice must be

submitted by April 21, 1997.

ADDRESSES: Commenters must send an

original and two copies of their

comments referencing Docket Number

F–97–CS3A–FFFFF to: RCRA Docket

Information Center, Office of Solid

Waste (5305G), U.S. Environmental

Protection Agency Headquarters (EPA,

HQ), 401 M Street, SW., Washington,

DC 20460. Comments may also be

submitted electronically through the

Internet to: rcradocket@epamail.epa.gov. Comments in

electronic format should also be

identified by the docket number F–97–

CS3A–FFFFF. All electronic comments

must be submitted as an ASCII file

avoiding the use of special characters

and any form of encryption.

Commenters should not submit

electronically any confidential business

information (CBI). An original and two

copies of the CBI must be submitted

under separate cover to: RCRA CBI

Document Control Officer, OSW

(5305W), 401 M Street, SW.,

Washington, DC 20460. For other

information regarding submitting

comments electronically, viewing the

comments received, and supporting

information, please refer to the

proposed rule (61 FR 17358 (April 19,

1996)). The RCRA Information Center is

located at Crystal Gateway One, 1235

Jefferson Davis Highway, First Floor,

Arlington, Virginia and is open for

public inspection and copying of

supporting information for RCRA rules

from 9:00 a.m. to 4:00 p.m. Monday

through Friday, except for Federal

holidays. The public must make an

appointment to view docket materials

by calling (703) 603–9230. The public

may copy a maximum of 100 pages from

any regulatory document at no cost.

Additional copies cost $0.15 per page.

FOR FURTHER INFORMATION CONTACT: For

general information, call the RCRA

Hotline at 1–800–424–9346 or TDD 1–

800–553–7672 (hearing impaired)

including directions on how to access

electronically some of the documents

and data referred to in this notice

electronically. Callers within the

Washington Metropolitan Area must

dial 703–412–9810 or TDD 703–412–

3323 (hearing impaired). The RCRA

Hotline is open Monday–Friday, 9:00

a.m. to 6:00 p.m., Eastern Time.

Documents referred to in this notice

are available from two electronic

sources: the CLU–IN and EMTIC

bulletin boards. The CLU–IN bulletin

board is accessible by modem at phone

number 301–589–8366 or by Telnet at

clu-in.epa.gov. The EMTIC bulletin

board is accessible by modem at phone

number 919–541–5742 or over the

Internet at http://ttnwww.rtpnc.epa.gov/

. The reader should note that figures,

diagrams, and appendices may not be

available in these electronic documents.

For other information on this notice,

contact H. Scott Rauenzahn (5302W),

Office of Solid Waste, 401 M Street,

SW., Washington, DC 20460, phone

(703) 308–8477, e-mail:

rauenzahn.scott@epamail.epa.gov.

SUPPLEMENTARY INFORMATION: On April

19, 1996, EPA proposed revised

standards (herein referred to as ‘‘the

proposed rule’’) for hazardous waste

combustors (HWCs, i.e., incinerators

and cement and lightweight aggregate

kilns that burn hazardous waste). See 61

FR 17358.

I. Introduction and Background

In the proposed rule, EPA proposed

requiring that continuous emissions

monitoring systems (CEMS) for

particulate matter (PM) and total

mercury (Hg) be used for compliance

with the proposed PM and mercury

emission standards. To require CEMS

for compliance the Agency, among other

things, determines that the CEMS are

commercially available and meet certain

performance specifications. To make

these determinations, the Agency

routinely tests CEMS available in the

marketplace. EPA published a notice

inviting vendors of PM and Hg CEMS to

participate in a CEMS demonstration

test program. (See 61 FR 7232, February

27, 1996). Ten vendors responded to the

Agency’s invitation. They donated nine

devices for the test program: six PM

CEMS and three Hg CEMS.1

Today the Agency is providing notice

and opportunity to comment on the

following documents resulting from its

CEMS demonstration test program: (1)

Site-specific Quality Assurance Test

Plan: Method 301 Validation of a

Proposed Method 101B for Mercury

Speciation, with Appendices, dated

September 27, 1996; (2) Site-specific

Quality Assurance Test Plan: Total

Mercury CEMS Demonstration, Volumes

1 and 2, dated October 11, 1996; (3) Sitespecific Quality Assurance Test Plan:

Particulate Matter CEMS

Demonstration, Volume 1, dated August

7, 1996; and (4) Status Report IV:

Particulate Matter CEMS

Demonstration, Volumes 1 and 2, dated

February 12, 1997. The purpose of this

notice of data availability (NODA) is to

obtain comment on the Agency’s

approach, as described in these

documents, prior to the end of the

demonstration tests. Comments received

will, to the extent possible, be

incorporated into the demonstration test

programs. EPA plans to follow this

NODA with a second notice after the

testing program has completed or is near

completion. That final notice will

contain what EPA believes will be final

draft performance specifications for

these CEMS.

The reader should note that one of

these documents, the PM CEMS

demonstration test status report, is a

draft report which is evolving over time.

The report will be added to and

modified substantially as the program

progresses. Therefore, conclusions and

discussions in this report do not

necessarily represent EPA’s final views.

They are included in this NODA so the

reader can fully evaluate the Agency’s
Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules 13777

2The Beta 5M CEMS is participating in this

demonstration as well.

3The ESC P5A CEMS is participating in this

demonstration as well.

approach and comment on this

approach prior to the end of the testing

program.

The remainder of this notice describes

the demonstration test programs for PM

and Hg CEMS. It serves as an overview

for the reader and brings to the reader’s

attention certain areas where EPA

requires input.

II. The PM CEMS Demonstration Tests

A. Background

EPA previously tested PM CEMS at

two other sites, the Rollins incinerator

in Bridgeport, NJ, and the LaFarge

cement kiln in Fredonia, KS. Both were

short-term tests to determine whether

further testing is warranted.

The purpose of the Rollins Bridgeport

tests was to qualitatively determine

whether vendor claims that PM CEMS

can be used for compliance with a PM

standard was feasible and to gain

insights on the scope and nature of

future tests. Three devices were tested at

Rollins: a Sick RM200 light-scattering

CEMS; a BHA CPM1000 time dependant

optical transmission CEMS; and an

Emissions SA Beta 5M β-gage CEMS.2

Due to the limited nature of this

investigation, though, there were certain

deficiencies in these tests which make

quantitative comparisons of this data to

other data difficult. For instance a

calibration of the instruments cannot be

performed because manual method data

was obtained over only two particulate

emission loadings, the measured range

of emissions was less than one-third of

the proposed HWC PM standard, and

only eight valid manual method

measurements were made. However, we

did determine that optically based PM

CEMS, such as the light-scattering and

time dependant optical transmission

instruments, had a step function

increase in their output when entrained

water droplets were encountered in the

gas stream.

Additional tests were conducted in

May 1995 at the LaFarge cement kiln in

Fredonia, KS. The purpose of these tests

was to conduct a full calibration of the

instruments in accordance with the ISO

(International Standards Organization)

specification, to better determine

whether these CEMS could be used for

compliance with a PM standard and

whether the ISO performance

specification could be used as a basis of

a proposed PM CEMS performance

specification, and to gain insights on

future testing. Two devices were tested

at LaFarge: the Sick monitor used in the

Rollins tests and an ESC P5A.3 Both are

light-scattering devices. Both devices

were installed in April 1995 and were

operated continuously on the cement

kiln through July 1995. At these tests,

EPA successfully calibrated these

devices in May 1995 using nine valid

pairs of M5 runs at three PM loadings.

Additional PM measurements were

made approximately one and two

months after the initial calibration. EPA

gained the following insights during this

test program:

—The ISO specification can be used as

a basis for any performance

specification EPA develops and that

the instruments could be calibrated to

particulate emissions obtained from

manual method data.

—Response of the instruments to

changing PM concentrations was

generally better at this cement kiln

than at the previous Rollins test.

—Statistics resulting from these

calibrations barely passed the ISO

specification. Other countries (such as

Germany) suggest that 15

measurements be made instead of 9 to

improve calibration statistics.

Therefore, more than 9 measurements

may be necessary.

—The current Method 5(M5) had

limitations in measuring low-level

particulate emissions due, in large

part, to the difficulty of the extraction,

filter recovery, and weighing steps.

This limitation likely lowered the

calibration statistics determined from

the data obtained during these tests.

—PM CEMS could be used for

compliance with a PM standard, but

longer term demonstration testing is

necessary to ascertain the device’s

long-term durability.

The calibration results are

summarized in Table 1, below.

TABLE 1.—MAY 1995 CALIBRATION RESULTS FROM THE LAFARGE PM CEMS TESTS

CEMS Correlation coefficient (r)

Confidence interval

(CI0.95)

(percent)

Tolerance interval

(TI0.95)

(percent)

ISO Performance Specification .................................................................................................... 0.90 25 35

Sick RM200 .................................................................................................................................. 0.92 17 29

ESC P5A ...................................................................................................................................... 0.90 20 32

B. Site Selection

For the PM CEMS demonstration

tests, EPA selected the DuPont

Experimental Station hazardous waste

incinerator in Wilmington, DE. The

DuPont incinerator receives a variety of

wastes from many DuPont facilities in

northern Delaware. As such the waste

input to the incinerator is like that of

many commercial incinerators.

The DuPont incinerator has a Nichols

Monohearth as its primary combustion

chamber. Waste is fed to this

combustion chamber using a ram feeder

for solid waste, a cylindrical chute for

batched waste material, and a Trane

Thermal liquid/gas waste burner. The

primary chamber exhausts to a

secondary chamber (afterburner) where

waste is fed using a Trane Thermal

burner. The flue gas then travels

through a spray dryer, then through a

cyclone separator, where dissolved and

suspended solids are removed. The

cyclone system discharges to a reverse

jet gas cooler/condenser which reduces

the gas temperature to the dew point.

The flue gas then travels through a

variable throat venturi scrubber which

removes additional particulate and

some acid gasses. The venturi scrubber

exhausts into an absorber neutralized

with soda ash scrubbing solution to

absorb acid gasses. The absorber also

subcools the flue gas before traveling

through a chevron-type mist eliminator.

After passing through the mist

eliminator, the gas travels through a set

of electro-dynamic venturis (EDVs)

which are used to remove fine

particulate along with metals that

condense onto the fine particulate as a

result of the gas subcooling. The gas

then travels through a set of centrifugal

droplet separators and an induction fan,

is reheated to eliminate any visible

plume, and is finally discharged to the

atmosphere through the stack. A full

description of the incinerator as well as
13778 Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules

4Feeds which affect PM emissions include

metals, other solids, and chlorinated solvents.

a diagram of the system is contained in

section 2.2 of the PM Test Plan.

EPA chose to perform the PM CEMS

tests at an incinerator because, under a

normal range of operating conditions,

incinerators present a worse case

exhaust stream to challenge multiple

PM CEMS technologies in a long-term

test program. For the purpose of

demonstrating the capabilities and

limitations of PM CEMS, a worse case

exhaust stream would consist of high

moisture (i.e., greater than 20%),

average PM levels below the proposed

emission limit, and PM with a wide

variation in physical properties (such as

composition, particle size distribution,

shape, color). Incinerators fulfill this

worst-case need in three main ways.

First, commercial incinerators and some

on-site incinerators, including the

DuPont facility, burn a wide variety of

waste as their primary feedstream. The

wide variety of the primary feedstock 4

has a higher potential to produce highly

variable particulate, which is a worst

case test for PM CEMS. This is not the

case for cement or light-weight aggregate

kilns (CKs or LWAKs, respectively.)

These sources primarily feed particulate

rich process ingredients (limestone and

fly ash for CKs and slate, shale, and clay

for LWAKs). As a result, PM in the flue

gases from both CKs and LWAKs are

likely to be overwhelmed by the process

dust and be more uniform than those

from an incinerator. Second, many

incinerators are equipped with wet air

pollution control system (APCS)

technologies which are able to meet the

proposed PM emission limit and

produce high moisture. Finally, these

APCS technologies produce a narrow

PM size distribution (i.e., primarily less

than 1 micron). This narrow size

distribution is typical of emission levels

from wet APCS technologies that are

expected to be installed on HWCs to

meet the upcoming MACT standards.

The DuPont incinerator was chosen

because:

—PM emissions were expected to range

from 0.005 to 0.075 gr/dscf (that is, 17

to 250% of the proposed HWC PM

standard), depending on how the

facility operated;

—The facility accepts ‘‘small’’ batches

of many waste streams and has

limited capacity to burn many waste

streams simultaneously, thereby

assuring more dramatic changes in

particulate concentrations and

physical characteristics in shorter

time intervals, relative to a larger

commercial facility;

—The facility has no ESP or fabric filter

for PM control;

—The facility was willing to participate

in the test program and allow

necessary modifications to be made;

—The facility was willing and able to

vary operating conditions as required

to perform the PM CEMS calibrations;

and

—Physical access, both for sampling in

the stack and for equipment and

personnel on the adjacent platform,

was available to locate six PM CEMS

and a test crew.

A detailed description of the site

selection is located in section 1.4 of the

PM Test Plan.

C. Revised Manual Method for PM

One issue which PM CEMS vendors

raised and which was noted during the

LaFarge tests was that the current

manual method for PM (Method 5,

herein refered to as M5,) may be

inadequate to make the low-level

measurements required for PM CEMS

calibrations. EPA determined that much

of this error comes from sample

recovery and analysis. Stacks with high

acid gas, water, and/or adhesive

concentrations (i.e., cement kiln clinker)

in the flue gas make the filter stick to

the filter housing. As a result, filter

recovery is difficult. For this reason,

EPA chose to modify M5 slightly.

The modification employs the use of

a light-weight filter assembly. The fronthalf and filter assembly are first pretared. The filter assembly then replaces

the current M5 filter housing in the

heated box. After measurement, the

entire assembly is desiccated and

weighed. This way the M5 extraction

step is eliminated without making

fundamental modifications to M5 itself.

Given that this change to M5 is minor

and only affects the extraction and

analysis steps, EPA does not believe that

a full field validation of the

modification was necessary. Instead the

Agency tested those parts of the method

which changed to ensure that those

parts of the process are as good as the

current M5. EPA has initially

determined that this modification is

acceptable. Completion of this analysis,

including a full write-up of the new

method, is expected soon. A full

description of this method will be given

in the later CEMS NODA.

EPA expects this modified method for

particulate measurements would be

required for use when calibrating PM

CEMS.

D. The PM CEMS Demonstration Test

The PM CEMS demonstration tests

started in September 1996 and are

expected to continue until May 1997 or

later. The test program started with an

initial calibration of the instruments and

followed with response calibration

audits (RCAs) and absolute calibration

audits (ACAs) every four weeks. The

program also involves continuously

recording the CEMS data for the

duration of the program, documenting

daily calibration and zero checks,

documenting all performed

maintenance/adjustments, and

documenting all periods in which data

was not available.

A second important aspect of the

demonstration tests is to evaluate the

proposed performance specification and

data quality objectives themselves.

Proposed performance specification 11

(PS 11) was drafted and proposed with

the idea that it would be modified based

on what these tests showed. The final

promulgated specifications will be

based on the data obtained through

these tests.

E. PM CEMS Technologies Tested

The six PM CEMS being tested

represent three separate PM CEMS

technologies: light-scattering, beta gage

(β-gage), and impaction energy devices.

Each technology is described below.

Full descriptions of each PM CEMS are

found in section 2.7 of the PM CEMS

Test Plan and in the proposals

submitted by the vendors. Vendor

proposals are found in docket item

S0205. All instruments participating in

this program are provided to the

government at no charge.

Light scattering devices work by

sending a light beam across the flue gas

and measuring the amount of light

reflected back to a detector located at

some angle (other than straight-path

transmissivity) from the light source.

These devices can be used either in-situ

(i.e., in the stack) or extractively. These

devices are not complex, relative to

other instruments, and as such are

relatively inexpensive to purchase. They

also have few moving parts and

consequently require little maintenance.

These CEMS are, however, sensitive to

PM characteristics, including

composition, density, size distribution,

and index of refractory. Three light

scattering devices are participating in

the program: Sigrist Photometer AG

model KTNR (supplied by Lisle-Metrix),

Durag model DR–300, and

Environmental Systems Corporation

(ESC) model P5A. All three CEMS are

installed on more than a hundred stacks

worldwide.

β-gage instruments continuously

sample extracted flue gas PM on a filter

tape. After the PM sample is collected,

the tape moves so that the collected PM

is located between a carbon-14 beta
Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules 13779

5All PM CEMS in this testing program will be

calibrated against the manual method. The claim

that β-gage PM CEMS do not require a calibration

will be tested as part of this test program.

radiation source and a detector. This

measurement is compared to a

measurement done on the blank filter to

obtain the mass of the collected

particulate. As such, these CEMS are

continuous samplers but batch

analyzers. These devices are quite

complex and as a result cost more than

light-scattering devices. Their

complexity also means they require

more maintenance and, as a result,

experience more down-time than lightscattering devices. However, these

devices are relatively independent of

the PM characteristics and vendors

claim a site-specific PM calibration is

generally not required.5 Two β-gage

devices are participating in the program:

Verewa model F–904–KD (supplied by

Monitor Labs), and Emissions SA model

Beta 5M (supplied by Environnement

USA). Both CEMS are installed on more

than a hundred facilities worldwide.

The third type of PM CEMS

technology is an impaction energy

device supplied by Jonas Consultants,

Inc. This monitor operates by detecting

shock waves caused by particles

impacting a probe inserted into the flue

gas. The device counts the number of

impacts and the energy of each impact.

This information, coupled with the

knowledge of flue gas velocity, allows

the calculation of particulate mass and

thus concentration. However, the probe

does alter the velocity profile of the flue

gas near the probe which, in principle,

affects the instrument’s response. Thus,

EPA believes a site-specific calibration

is necessary to ensure good instrument

response. This device has been installed

at few locations, mainly for process

control use in steam, and not for

compliance with a flue gas PM standard.

F. Demonstration Test Report

EPA seeks comment on the document

Particulate Matter CEMS

Demonstration: Status Report IV,

provided in the above referenced

docket. This document describes the

interim results from the PM CEMS

demonstration tests EPA is conducting.

It contains an analysis of data obtained

from the initial calibration through the

Relative Calibration Audit (RCA) in

January 1997. Specific aspects of the

report are discussed below. Subsection

1 describes the limitations EPA has

experienced in this test program.

Subsection 2 discusses general testing

issues. Subsection 3 describes the PM

CEMS performance characteristics

observed during the initial (and

subsequent) calibration and the RCAs.

Subsection 4 describes issues associated

with the proposed performance

specifications.

Note that many of the issues

described in this section may also apply

to other CEMS, such as the Hg CEMS

described in the next section.

Consistency between the two programs

will be maintained by handling similar

issues in a similar manner in both

programs.

Overall, EPA believes the PM CEMS

demonstration is making progress. EPA

was able to calibrate all of the installed

devices. The subsequent RCAs have

proved those calibrations to be reliable

over time. EPA also believes that the

proposed performance specifications

will need to be modified based on the

data and experiences coming out of this

program.

1. Limitations of the Test Program

a. CEMS downtime. One limitation of

the program is that, unlike facility

personnel, EPA is not on-site all the

time. As described in the test plans,

EPA travels to the site every two weeks

to, among other things, perform any

maintenance the instruments might

require. This causes CEMS downtime

occurring during the program to be

overstated relative to what a real facility

would experience if it were using one of

these instruments for compliance.

In addition, CEMS purchased by a

facility usually come with a supply of

spare parts so the facility can make

minor repairs without incurring

substantial downtime. In this program

however, EPA was not supplied with

many of the spare parts it would

otherwise get if it had purchased the

instruments. Parts required for routine

maintenance must be ordered from the

supplier as needed rather than drawing

them from the facility’s store of spare

parts. It takes more time to order parts

than to draw from the store of spare

parts on-site, so the CEMS are down

longer than they would be if the CEMS

were purchased by a facility for

compliance.

Finally, there tends to be no USbased, trained service technicians to

conduct major repairs on many of these

instrument. Technicians from the CEMS

manufacturer’s native country are often

flown in to provide specialized service.

Many of the parts must also be ordered

from suppliers in other countries. This

means that, if a major repair is required,

service and parts must be obtained from

overseas. This takes more time than it

would if service and parts were

available in this country, and further

overstates CEMS downtime.

This is important because one thing

EPA is trying to gage in this program is

data availability. Data availability is one

minus the CEMS downtime, expressed

as a percentage. If downtime is

overstated, data availability will be

understated. EPA anticipates remedying

this situation by subtracting out

downtime associated with these

limitations. For instance, if a CEMS

requires a minor repair and goes down

soon after EPA leaves the facility, the

CEMS will be inoperable for two weeks,

until EPA arrives back at the facility. If

the repair takes eight hours to perform,

then EPA will count the downtime as 8

hours, not two weeks. The same

approach will be used for the Hg CEMS

program as well.

b. Absolute Calibration Audits. In the

proposed rule, EPA proposed requiring

facilities to conduct ‘‘Absolute

Calibration Audits’’ (ACAs) every

quarter. These tests would be conducted

with NIST traceable standards to ensure

the analytical parts of the instrument

were still working properly.

Unfortunately, only two vendors (Sigrist

and Durag) have supplied us with these

standards. EPA will conduct ACAs on

the instruments as the standards arrive.

At this time, NIST does not have

traceable standards for these

instruments. However, German TuV

versions of these standards (called

‘‘linearity test kits’’) exist for most of

these CEMS. We believe that these TV

standards are sufficient substitutes for

the yet-to-be-developed NIST standards

to conduct the ACAs.

If these test kits are generally not

available to facilities, then EPA solicits

comment on whether the ACA approach

should be modified. For instance, it

might be adequate to require a device to

make daily internal zero and span drift

measurements and corrections. Most

devices are already configured to make

both zero and span drift measurements

and corrections.

c. Inability to repeat tests. It is

infeasible to repeat a test conducted

under a set of conditions at this facility

due to the wide variety of ‘‘small’’

batches of waste the facility processes

and the hysteresis effect of the APCD.

Like a commercial facility, this

incinerator accepts a wide variety of

wastes, both hazardous and industrial,

from all DuPont facilities in northern

Delaware. The incinerator often

incinerates multiple wastes

concurrently. Those wastes arrive at the

incinerator in a random fashion. Batches

are also quite small relative to what

would be experienced at a commercial

facility, meaning that transients in PM

concentrations and characteristics are
13780 Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules

6Apparently, there is a 35°F temperature increase

across the induction fan that can not be overcome.

7Based on the Rollins data, EPA qualitatively

concluded that while entrained water droplets did

induce a step function increase in the output from

in-situ light-scattering PM CEMS, it did not affect

the calibration so much as to cause the calibration

to fail under this condition. The step function

increase was caused by the in-situ light-scattering

PM CEMS mistaking entrained water droplets for

particulate.

This leads EPA to believe that a facility which

uses an in-situ light-scattering PM CEMS for

compliance and has entrained water droplets in the

stack gas may experience situations where the

actual PM emissions are lower than those reported

by the monitor. The risk for a such a facility which

is in compliance with the PM standard is that it

may experience an increased number of false noncompliances with the PM standard. EPA hopes to

quantify the effects of entrained water droplets on

light-scattering PM CEMS so it can quantify the

risks associated with a false non-compliance in this

situation.

This possible false non-compliance possibility

can be avoided if the light-scattering PM CEMS is

configured such that it extracts flue gas from the

stack, heats it to above the highest possible dew

point temperature, and measures the heated,

extracted gas. One light-scattering PM CEMS in the

program is so configured. Others can be similarly

configured to avoid this potential problem. The

trade-off is that extractive light-scattering PM CEMS

cost more than in-situ units.

8 It is believed that the cause is a manual method

sample is not obtained due to spacial differences

between the sampling locations of the manual

method and CEMS.

more pronounced and shorter in

duration.

Further complicating this is the fact

that this incinerator is a zero water

discharge facility. This means

wastewater from the wet scrubber is

recycled to the spray dryer (upstream

from the scrubber) and injected back

into the incinerator exhaust gas. This

results in a hysterisis effect; wastes fed

to the incinerator at one time

accumulate in the pollution control

system and affect the emissions later.

Both situations affect our ability to

repeat tests and, consequently, to show

that CEMS have the same response to

the same particulate at a later time.

d. Inability to test with entrained

water droplets. One thing that attracted

EPA to this facility was that it is an

incinerator with a wet air pollution

control system and a reheat system to

vaporize water droplets that would

otherwise be entrained in the stack gas.

EPA anticipated being able to conduct

tests with entrained water droplets in

the stack by turning off the reheat

system. The Rollins tests showed that

entrained water droplets are mistaken as

particulate by light-scattering PM

CEMS. EPA wished to test the lightscattering devices with entrained water

droplets so it could quantify the effects

of entrained water droplets on lightscattering PM CEMS.

Such tests were planned and

conducted in November 1996. But no

entrained water droplets formed despite

turning the reheat off. EPA and DuPont

have since concluded that we are unable

to predict when entrained water

droplets will occur at the incinerator as

currently configured.6 Therefore, it is

unlikely that EPA will be able to

conduct tests with entrained water

droplets as part of this program.

One approach EPA may take is to use

the limited data EPA has from its earlier

Rollins Bridgeport tests of PM CEMS

and draw whatever conclusions it can

from that data.7 However, EPA believes

this data is insufficient to quantify the

effects of entrained water droplets. For

this reason, EPA requests data which

quantifies the effects of entrained water

droplets on the calibration of lightscattering PM CEMS.

2. General Test Issues

a. Handling of Outliers. Two types of

outliers were experienced so far in the

program: paired data and statistical

outliers. Each is discussed below.

i. Paired Data Outliers. EPA is

conducting its PM measurements in

such a way that a pair of (two) trains

concurrently sample the flue gas at the

same time in the same plane of the

stack. The average of these two

concurrent trains is the PM emissions

measured by the manual method for a

given run. This methodology usually

means the results from the two trains

are similar. This conclusion is

substantiated by most of the data

obtained during the test program.

However, there were instances when

the results from the pair of concurrent

trains differed substantially. This leads

EPA to believe that there was a problem

with one or both of the trains which

comprise such a run. As a result, EPA

developed a quality criteria requiring

that the pair of trains which comprise a

run not differ substantially. EPA

quantitatively defined this substantial

difference by looking at historical M5

data. Data indicate that results from

paired trains such as these agree with a

relative standard deviation (RSD) of

10%. Therefore, nearly all data should

agree to within three times this RSD, or

to within 30% of each other. If the

results of paired trains disagree by more

than 30%, the whole run would be

thrown out.

EPA anticipates that other situations

will arise in which it will need to

disregard data which substantially

differs from the historical data in other

ways. The Agency would have serious

reservations regarding this practice of

defining what is or is not acceptable

data after the fact if this were a

compliance determination. However,

this is not a compliance evaluation, and

EPA does not believe the same cautions

apply. In addition, EPA is unable to

develop these quality criteria prior to

the start of the program because it does

not have a history of PM data from this

facility upon which to base such quality

criteria. EPA believes this approach of

developing quality criteria as the

program progresses is reasonable given

the unique situation here.

ii. Statistical Outliers. Another type of

outlier data experienced during the

program is referred to as ‘‘statistical

outliers.’’ Statistical outliers are data

which are more than three (3) standard

deviations away from the linear

regression line that represents the

calibration of the instruments. EPA does

not have an opinion on how to handle

statistical outliers and requests

comment on how to proceed.

In implementing manual calibration

tests for other CEMS, EPA routinely

allows outliers of this kind to be

disregarded when developing the

calibration curve. The Agency’s logic for

disregarding this data is that it is known

that the manual method sometimes

dramatically under-reports emissions

for unknown reasons.8 Using this outlier

data in the calibration of other CEMS is

unwise because: (1) The error cannot be

accounted for by known science; and (2)

eliminating the data causes the slope of

the calibration curve to be steeper (i.e.,

numerically larger), therefore it is

protective of the environment to

exclude this outlier data. In the case of

other CEMS, the statistical difference is

reasonable justification for proving that

a problem occurred while obtaining that

data point.

Upon closer examination here,

however, it is not clear whether the fact

that the data appears to be statistically

different is ample justification to

disregard the data. Statistical tests

usually involve the testing of a sample

population to see if the sample data is

from the same population as data you

are comparing it to. It involves

establishing a null hypothesis which

states that the sample is part of the

population (H0: μs = μp or σs

2 = σp2, that

the mean or variance, respectively, of

the sample data is equal to that of the

population). If the statistical test infers

that the null hypothesis is not true, then

an alternate hypothesis, stating that the

data is from a different population than

the one you are comparing it to, is

accepted (HA: μs ≠ μp or σs

2 ≠ σp2, that

the mean or variance, respectively, of

the sample data is different than that of

the population). In our case here, the
Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules 13781

9 EPA’s Office of Research and Development

recently concluded a study of how changes in

particulate properties affect the output of PM

CEMS. The report describing the results of this

study is not expected to be completed until

September 1997.

10The proposed performance specification states

that the 95% confidence interval for the calibration

curve must be no more than ± 20% of the emission

limit at the emission limit. This is a single point

test. In the case where a facility cannot calibrate up

to or above the emission limit, the 95% confidence

interval test for the calibration curve would be ±

20% of the emission limit at the point resulting in

the highest PM CEMS output. The same approach

would be used for the tolerance interval test as well.

11Results from the Jonas analyzer, however, is not

reported. The Jonas analyzer reported results in

terms of emission rate (g/s) rather than emission

concentration (mg/dscm). Time is needed to

analyze and correct how to correct these values to

the proper units.

fact that a statistical outlier is more than

three standard deviations away from the

linear regression line would likely lead

one to reject the null hypothesis and say

that the outlier is from a different

population than what is represented by

the linear regression line. After

determining the data are different, one

must determine why. This analysis is

important because it will help

determine whether the data should be

kept in the original sample or

disregarded.

This situation differs from the other

CEMS case because PM CEMS have

known sensitivities to changes in what

they are measuring, i.e., moisture and

the particle’s characteristics, such as

density, shape, size distribution,

refractory (color), etc. Unfortunately, we

do not know the effects of these changes

on the outputs of PM CEMS.9 In other

words, EPA is uncertain whether the

statistical outliers were caused by an

error in the manual method

measurement process (in which case the

data would be thrown out) or if the error

was caused by the CEMS overstating (or

understating) the PM emissions due to

changing particulate properties (in

which case the data would be kept in

the data set). In addition, most of the

statistical outliers experienced in this

program are ones in which the manual

method result is higher than what the

PM CEMS report. Therefore, it would

likely be more appropriate to keep the

data in the data set in this case.

EPA is currently pursuing statistical

ways of dealing with outliers and

requests comment on how to deal with

this situation. One alternative is to

establish a stringent specification for the

correlation coefficient (yet within the

bounds of the data obtained in this

program) and allow facilities to throw

out, but report, data that is farthest away

from the linear regression line. ‘‘Farthest

away’’ could be defined on either a

relative or absolute standard deviation

basis. The facility would then substitute

in better data if needed to meet the

minimum number of samples or other

performance specification requirements.

b. Extrapolating Data. Another issue

is that this facility, while having a PM

permit limit of 0.08 gr/dscf, cannot emit

that much particulate. We expect that

similar situations exist throughout the

industry. This is a concern because EPA

proposed that facilities calibrate their

PM CEMS to up to two (2) times the

emission limit. If it is physically

impossible for a facility to emit this

much particulate, it obviously cannot

calibrate the instruments that high.

Therefore, the Agency seeks comment

on whether the following approach is

acceptable. EPA believes a facility

should calibrate the CEMS up to the

point where, based on historical data

the facility has, the facility is producing

the most particulate. This point will

serve as the ‘‘high’’ calibration range for

this facility’s PM CEMS. In addition, the

facility would use the available data and

extrapolate the linear regression line

beyond the high calibration range for

instances where the emissions are

higher than the historical data indicate.

As the historical data grow for this

facility, the facility may notice times

when the PM emissions are more than

what the previous historical data

indicated. In this event, the facility

would re-calibrate the CEMS under the

previously unknown condition(s) which

result in higher emissions than the old

historical data indicated.

A unique case exists when the highest

possible emission level is less than the

emission standard. In this case the

calibration data point resulting in the

highest PM CEMS output would be the

point where the confidence and

tolerance interval tests would be

conducted.10

c. Correcting for temperature and dry

basis. Some of the PM CEMS need to

correct their output for stack

temperature and moisture. These

corrections have not been done for the

data in this report. While these

corrections will have a minor effect, the

data will change slightly after the

corrections are made. EPA is now

correcting the data to account for

changes in temperature and moisture.

Future reports will report all data

properly corrected for temperature and

moisture.

3. PM CEMS Performance

Characteristics

One important aspect of the program

is to test and verify that the performance

of these devices meet the characteristics

described in the proposed performance

specification (PS) 11. It also serves as a

test of the performance specification

itself and proposed data quality

objectives for CEMS described in the

proposed Appendix to Subpart EEE.

Data from this demonstration test

program will be used to revise PS 11

and the data quality objectives as

necessary.

Table 2 lists each of the monitors

being tested, the proposed performance

requirement for the devices, and the

actual performance observed during the

test program.11 The results in Table 2 do

not include data outliers which have

been excluded from the analysis, such

as ‘‘paired data outliers.’’ The reader

should note that the correlation

coefficient, confidence interval, and

tolerance interval tests apply only to the

calibration. These values are reported,

however, for subsequent RCAs even

though they do not apply in this

situation. Specific discussion on each

performance specification is discussed,

below.

EPA has been able to generate a linear

regression line for the various PM

CEMS. Performance of the devices are

nearly identical when one compares the

performance of an in-situ device to the

other in-situ device and extractive

devices to one another. In-situ units

seem to show better performance than

extractive units regardless of technology

of the CEMS.
13782 Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules

12Time constraints have required the Agency to

temporarily ignore the quadratic regression

approach described in the performance

specification. This analysis will be done for the

final report and the curve which best fits the data

will be presented.

13See above for the discussion of what to do

when it is not possible to calibrate to the emission

limit.

TABLE 2.—PERFORMANCE CHARACTERISTICS OF THE PM CEMS BEING TESTED

Performance specification Correlation

coefficient

(r)

Confidence

interval

(CI0.95)

Tolerance

interval

(TI0.95)

RCA test

(TI0.95)

Calibration

drift

(CD)

Zero drift

(ZD) CEMS Date of test

>0.90

±20% at

emission

limit

±35% at

emission

limit

≥75% of data

within

TI0.95

±2% of the

calibration

standard

±2% of the

emission

limit

ESA .............. Cal. .................................... 0.55 26 38 ........................ Pass ............. Pass.

01/97 .................................. 0.92 21 25 75 Pass ............. Pass.

All Data .............................. 0.46 35 40 ........................

Verewa ......... Cal. .................................... 0.69 27 32 ........................ No data ........ Pass.

12/96 .................................. 0.86 24 20 100 No data ........ Pass.

01/97 .................................. 0.93 18 25 100 Fail ............... Pass.

All data ............................... 0.76 18 23 ........................

Durag ........... Cal. .................................... 0.72 22 36 ........................ Pass ............. Pass.

11/96 .................................. –0.38 52 77 75 Pass ............. Pass.

12/96 .................................. 0.91 45 73 100 Pass ............. Pass.

01/97 .................................. 0.93 20 22 100 Pass ............. Pass.

All data ............................... 0.61 20 35 ........................

ESC .............. Cal. .................................... 0.71 22 36 ........................ Pass ............. Pass.

11/96 .................................. 0.87 24 31 88 Pass ............. Pass.

12/96 .................................. 0.92 42 69 100 Fail ............... Pass.

01/97 .................................. 0.93 20 23 100 Pass ............. Pass.

All data ............................... 0.68 18 32 ........................

Sigrist ........... Cal. .................................... 0.64 25 40 ........................ Pass ............. No data.

11/96 .................................. 0.87 24 31 88 Pass ............. No data.

12/96 .................................. 0.90 47 77 100 Pass ............. No data.

01/97 .................................. 0.92 21 24 100 Pass ............. No data.

All data ............................... 0.64 19 33 ........................

Note to Table 2: The initial calibration for the Durag, ESC, and Sigrist units was performed in September and October 1996. The initial calibration for the Verewa unit was performed in September and November. The initial calibration for the ESA unit was performed in September and

December.

a. Correlation Coefficient (r).

Proposed PS 11 states that the

correlation coefficient be at least 0.90

(See § 4.2.1). Tests to date indicate that

EPA may be unable to produce a linear

regression line which correlates as well

as the proposed performance

specification indicates.12 EPA believes

this is caused by the fact that this

facility is a worst-case facility for this

demonstration test program. EPA

believes the correlation coefficient

specification may have to be lower

based on the results of this testing.

Particulate properties depend largely

on the wastes fed and the accumulated

particulate in the APCS. These

properties vary considerably at this

facility, just as the types of wastes fed

to the unit vary. This variability in the

particulate properties causes a varied

response from the PM CEMS, which in

turn causes the correlation coefficient to

be lower than anticipated. This can be

avoided by developing a calibration

curve for every possible set of

particulate properties. However as

described in the next paragraph, this

may not be possible at this facility.

The calibration tests were done under

as wide a variety of operating conditions

as possible. The proposed performance

specifications and data quality

objectives would make a facility such as

this incinerator to have one calibration

for every given operating condition, not

one that fits all situations as EPA did

here. The Agency now believes the

proposed approach may not be possible

for this source. As mentioned,

particulate does accumulate in the

APCS causing wastes fed at one time to

influence the type of particulate that is

emitted later. In addition, the wastes

arrive at the incinerator in a random,

uncontrollable manner and in ‘‘small’’

batches. This makes it extremely

difficult for a facility such as this one to

determine what calibrations it needs

and which of those calibrations to use

at any given time. It might be best for

a facility such as this one to have one,

not many, calibrations to simplify

compliance. EPA seeks comment on

whether this approach, having one

calibration curve to cover every

circumstance rather than several for

each circumstance, is acceptable.

b. Confidence Interval (CI0.95).

Proposed PS 11 states that CI0.95 be

within ± 20% of the emission limit at

the emission limit. (See § 4.2.2). This

test is done by taking the data from the

initial (or subsequent) calibration,

calculating the 95% confidence interval

for the regression line, and verifying

that the upper confidence limit at the

emission standard is less than the

emission standard plus 20% and that

the lower confidence limit at the

emission standard is more than the

emission limit minus 20%. In other

words, this is a single point test at the

emission limit.13 Based on standards

proposed for HWCs, this means the

upper confidence limit must be less

than 83 mg/dscm and the lower

confidence limit more than 55 mg/dscm

calculated at the emission limit.

Confidence intervals calculated for

these PM CEMS are higher than, but

close to the proposed specification. This

higher value for the confidence interval

is probably the result of EPA’s approach

of generating one calibration curve at

this worst-case facility.

c. Tolerance Interval (TI0.95). Proposed

PS 11 states that TI0.95 be within ±35%

of the emission limit at the emission

limit. (See § 4.2.3). This test is done by

taking the data from the initial (or

subsequent) calibration, calculating the

95% tolerance interval for the regression

line, and verifying that the upper

tolerance limit at the emission standard
Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules 13783

14Again, see above for the discussion of what to

do when it is not possible to calibrate to the

emission limit.

15One of the β-gage devices has two sample

collection tapes to allow for the continuous

sampling of flue gas, but the other does not. The

truly continuous unit collects particulate on one

tape as the second tape is being analyzed. The unit

with one tape samples the extracted gas onto that

tape and then analyzes it. This unit is not a

continuous sampler since it is not sampling stack

gas while measuring the accumulated particulate on

the tape. The device with one tape could be

configured with two tapes to allow for the

continuous sampling of stack gas. It was not

configured with two tapes for this test program

because the vendor was unwilling to incur the cost

of supplying such a device for this test program.

16See above for the special case where a facility

cannot calibrate the PM CEMS to the emission

limit.

17Section 7.3 of the proposed performance

specification 11 for PM CEMS states that the

number of tests required for a response calibration

is 15. This should not be confused with the number

of tests for a relative calibration audit. Section 7.3

does not apply to RCAs.

is less than the emission standard plus

35% and that the lower confidence limit

throughout the calibration range is more

than the emission limit minus 35%.

Like the correlation interval test this is

also a single point test.14

The calculated tolerance intervals for

the various PM CEMS being tested are,

like the confidence interval, higher than

but close to the proposed specification.

d. Relative Calibration Audit (RCA)

Tests. The proposed data quality

objectives state that, to pass an RCA,

75% of the RCA data must lie within the

95% tolerance interval. (See § 5.2.3.1 of

the proposed appendix to Subpart EEE.)

All the CEMS passed all the RCAs.

Therefore, the initial calibration is still

valid over time despite the changing

operating conditions at the facility.

e. Calibration and Zero Drift (CD and

ZD). Proposed PS 11 states that CD be

within ±2% of the calibration standard

and that the ZD be within ±2% of the

emission limit. (See §§ 4.3 and 4.4,

respectively). This test would be done

during the ACA tests, which the

proposed quality assurance

requirements stated would be done on

a quarterly basis.

As discussed above, most of these

CEMS internally check zero and/or

calibration drift every day. In cases

where one or more of the checks are not

internally done, traceable standards are

required to perform the check. Most

vendors have not supplied these NIST

traceable standards (or an acceptable

substitute) for the ACAs. The ACAs for

this test program will be done every 4

weeks for these missing parameters as

soon as EPA obtains these standards

from the vendors.

Where data is available, most CEMS

routinely pass the zero and calibration

checks. In instances where the drift test

is failed, the CEMS automatically

adjusts the failed parameter to within

specifications. EPA is now quantifying

the ‘‘Pass’’ and ‘‘Fail’’ indicators shown

in the table. Future reports will quantify

values for zero and calibration drift

rather than express them in the

qualitative terms ‘‘Pass’’ and ‘‘Fail’’.

f. Response Time—Continuous CEMS.

Proposed performance specification 11

states that continuous-type CEMS

respond to a step increase in such a way

that the CEMS achieve 95% of the final

stable reading within 2 minutes of the

start of the step increase. (See § 4.5.1).

This requirement is to be certified by

the vendors. The vendors participating

in this program have done so. This

specification will not be tested during

this program unless EPA believes the

response time is suspect.

g. Response Time—Batch CEMS.

Proposed performance specification 11

states that the response (i.e., sampling)

time for batch-type CEMS be no more

than one-third of the averaging period.

(See § 4.5.2). The sampling time for

these CEMS are on the order of minutes

while the averaging period for the PM

standard was proposed to be two hours,

so this requirement has been met.15 But

this specification does raise several

issues which deserve consideration

here.

While the response time requirement

is met for the averaging period

associated with the standard, ten minute

and one hour averages were proposed

for PM CEMS when used as an

operating parameter, i.e., all times other

than during a comprehensive

performance test. The sampling time for

these devices is less than one third of

the one hour average, but not less than

one third of the short term ten minute

average. Further complicating this is the

fact that the sampling period for these

devices, while less than ten minutes, is

more than half of ten minutes. The

result is that no averaging could be done

to assure compliance with a ten minute

average. This raises the issue of whether

the sampling period for PM CEMS needs

to be less than one third of the ten

minute average. EPA believes not, since

this requirement is based on EPA’s

belief that a facility will want to base

compliance on the average of at least

three data points. If a facility is willing

to base compliance on fewer than three

data points, it could be allowed to do so.

This is particularly true for a ten minute

average which is likely to be quite high

relative to the standard or the one hour

average. Nonetheless, EPA seeks

comment on how to address this for the

final rule.

4. Issues Relative to the Draft

Performance Specification 11 for PM

CEMS

a. Performance Specifications which

Apply for the Calibration Curve. The

proposed data quality objectives were

specific that a tolerance interval test be

used during an RCA to determine

whether the calibration curve is still

valid. However, the data quality

objectives were silent on what tests

apply to determine whether the initial

calibration is valid. For this reason, EPA

wishes to clarify this point.

To test the validity of the calibration

curve, one must check to make sure the

calibration curve passes the correlation

coefficient (r), confidence interval, and

tolerance interval tests. The correlation

coefficient is a test of the curve’s overall

fit. If the calculated correlation

coefficient is greater than the one

published in the performance

specification, the calibration curve is

acceptable. The confidence interval test

is a single point test at the emission

limit.16 This verifies the fit of the

calibration at the emission limit, a

critical point when using a CEMS for

compliance. The tolerance interval test

is similar to the confidence interval test

in that it is a single point test.

The confidence interval and tolerance

interval tests, though, may be

redundant. Therefore, we seek comment

on whether only one of these tests

should be used. There is merit to

keeping both tests, though. The

confidence interval test, for instance,

ensures that the calibration curve is

accurate at the standard, a point where

a high degree of accuracy is required.

The tolerance interval test is unique in

that it sets the maximum deviation the

tolerance interval lines can be from the

linear regression curve at 35% of the

emission limit. Therefore, commenters

should focus their comments on

whether these tests are indeed

redundant. Would a failure of one test

conclusively mean the other test is also

failed? Conversely, would passing one

conclusively mean a facility would pass

the other? If so, which of these tests is

more stringent?

b. Number of Tests for the RCA.

During the course of this test program,

EPA has learned that it might be wise

to standardize the number of tests

required for the RCA.17 Other Appendix

B performance specifications require

that 12 tests be performed for relative

accuracy test audits (RATAs). (RATAs

are the equivalent to the RCA here.)

EPA believes the following approach

would be acceptable for RCAs and

requests comment on it. A facility
13784 Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules

18For the purposes of this discussion, mercury

species are defined as particle bound, ionic, and

elemental mercury.

19The reader should note that many methods are

currently being developed to speciate mercury

emissions. One of those other methods may be

better than the method chosen here. This method

was chosen because EPA knows how to perform

this method. Other methods are not so well

documented. Eventually a method other than the

one used here may be adopted as the EPA method

for mercury speciation.

20Likewise, a facility could also use Method

101A. M101A is a mercury-only emission

measurement method. M101A is identical to M29

except it uses mini-impingers.

would perform up to 12 manual method

measurements. Manual method tests

may be disqualified and fewer than 12

used if they fail method QA/QC or the

facility’s internal data quality standard,

but in no case may the number of RCA

tests be lower than 9. If fewer than 9

measurements remain after the quality

audit of the data, a new RCA test is

required. To pass an RCA, more than

75% of the qualifying, good data must

lie within the tolerance interval lines.

III. The Hg CEMS Demonstration Tests

A. Site Selection

For the Hg CEMS demonstration tests,

EPA selected the Holnam cement kiln #2

in Holly Hill, SC. This cement kiln cofired hazardous waste with other fuels,

including fossil fuels such as coal. As

such, this cement kiln is like many

other hazardous waste burning cement

kilns.

Holnam Holly Hill kiln #2 is 18.5 feet

wide and 580 feet long with a design

capacity of 2,100 tons of clinker per day.

The main ingredients in the cement

production are limestone, clay, alumina,

and iron. The facility also obtains

additional raw materials, such as fly

ash, to supplement raw materials. Raw

materials are ground, mixed with water,

and fed to the cold end of the kiln at a

solids content of about 65%. The hot

(discharge) end of the kiln is fired

primarily by coal, but petroleum coke,

waste carbon, shredded tires, hazardous

waste, fuel oil, and natural gas can also

be fired. Kiln #2 has a rated capacity of

600 M–Btu/hr. Gases pass through the

electrostatic precipitators (ESPs)

specifically designed and built for this

facility, through a transfer duct, and out

the exhaust stack.

EPA chose to perform the Hg CEMS

tests at a cement kiln for many reasons.

CKs tend to have higher levels of

mercury in their flue gas, relative to an

incinerator or an LWAK, because

mercury is fed to the kiln in the raw

material used for cement production.

Other HWCs can better avoid mercury

in their feed materials, so it is less likely

that mercury would be present in the

flue gases of those sources. Therefore, a

useful Hg CEMS demonstration program

can be conducted at a CK since it has

mercury in the flue gas. CKs also have

higher PM emissions relative to other

sources. The PM is also likely to contain

mercury. This is because the PM is

derived in large part from the raw

material that, in turn, can be a

significant source of the mercury fed to

the kiln. Particle bound mercury is

difficult for Hg CEMS to measure, so

this represents a worst case for these

instruments. Finally, CKs tend to have

air pollution control equipment to

control PM only. Other pollutants are

uncontrolled and may be present at high

concentrations. Since these pollutants,

such as SO2 and NOX, may interfere

with the Hg CEMS’s ability to measure

mercury, this again is a worst case

situation for Hg CEMS.

The Holnam Holly Hill cement kiln #2

was chosen because:

—Data indicated the mercury

concentration in the flue gas is 17 μg/

dscm without the need to spike

mercury;

—The facility was willing to host the

demonstration and allow the

necessary facility modifications;

—Physical access was available at the

transfer duct and stack; and

—There was room for installing the Hg

CEMS analyzers close enough to the

sampling point to meet the monitor’s

maximum sample line requirements.

A detailed description of this

selection decision is found in Section

1.3 of the Hg Test Plan.

B. Speciated Hg Manual Method.

One aspect of the program is to

determine how well these Hg CEMS

measure all species of mercury.18 Some

mercury monitors measure just

elemental mercury. Total mercury

monitors, or Hg CEMS like those

participating in this program, measure

all mercury regardless of species. Most

Hg CEMS measure total mercury by first

converting all mercury to elemental

mercury and measuring the amount of

elemental mercury in the treated flue

gas. Converting all mercury to elemental

mercury adds much complexity to the

instrument.

At the start of this program, no

method had been validated to measure

mercury by species. Many types of

speciated mercury methods are

currently being developed, so EPA

chose to validate one of those methods

to use in this program. This speciated

mercury method is tentatively called

Method 101B.19 The report, Site-specific

Quality Assurance Test Plan: Method

301 Validation of a Proposed Method

101B for Mercury Speciation, describes

the methodology used to validate the

method.

While EPA is not ready to release the

final report on this validation, some

mention of its validation status is

warranted here. The method passed all

Method 301 criteria without correction

with the exception of ionic mercury.

The Agency has not yet concluded

whether the method passed for ionic

mercury. The issue for ionic mercury is

that the HgCl2 spiking used for the

validation varied so much that it caused

the calculated relative standard

deviation to be much greater than

Method 301’s criteria of 0.50. EPA is

now studying how to eliminate the

effects of HgCl2 spiking from the data.

We will release the final validation

report after this concern has been

addressed.

Finally, EPA has not yet determined

whether this validation at this cement

kiln can be transferred to other sources.

Mercury species, primarily ionic forms

such as HgCl2, are very difficult to

generate, transport, and measure. EPA

plans to use this method at other

sources. Prior to doing so, though, we

will perform tests to determine how

well the validation at the cement kiln

transfers to these other sources. After

this work is completed, EPA will be able

to determine whether this method

should work at other sources. Until this

is done, however, EPA recommends that

a facility wishing to measure mercury

by species first conduct a full Method

301 validation of the speciated mercury

method prior to using it.

The reader should note that EPA has

no plans to require facilities to use

M101B. It was validated so EPA could

answer questions it had regarding the

ability of the Hg CEMS to measure all

species of mercury simultaneously. A

facility would continue to use Method

29 20 to measure stack mercury

emissions, including any stack tests

required for Hg CEMS.

C. The Test Plan

Testing started in August 1996 and

continued through September. In

October we discovered that all the Hg

CEMS had suffered equipment failures.

EPA met with the Hg CEMS vendors

soon after the problem was discovered,

and vendors responded to EPA’s data

availability concerns by increasing the

ruggedness of their equipment. Testing

resumed in December 1996. The

monitors have responded with less

failures since the modifications were

made.

As was the case in the PM CEMS

testing program, relative accuracy test
Federal Register / Vol. 62, No. 55 / Friday, March 21, 1997 / Proposed Rules 13785

audit (RATA) and ACA tests are being

performed every four weeks. Testing is

expected to continue through May 1997

or later.

An important aspect of the Hg CEMS

demonstration tests is to test the

performance specifications themselves.

Revised specifications will be

promulgated based on the data obtained

here and comments received in

response to the CEMS NODAs.

Vendor proposals for this test program

are found in docket number S0205.

D. Hg CEMS Demonstration Test

Due to the sudden stop and restarting

of the Hg CEMS demonstration test

program, EPA is not prepared to release

an interim report for this test program.

EPA does request comment on the

approach we are using to demonstrate

these Hg CEMS and how to address the

variability of spiking during the ACA

test.

1. Hg CEMS Demonstration Test

Approach

The Agency’s approach to

demonstrating the Hg CEMS can be

found in the document, Site-specific

Quality Assurance Test Plan: Total

Mercury CEMS Demonstration.

2. ACA Tests and Spike Variability

As described in the section above

concerning the Method 101B validation,

similar problems have been encountered

spiking known concentrations of

elemental (Hg0) and ionic (Hg∂2)

mercury to the CEMS. NIST traceable

permeation tubes are available for Hg0,

but not for Hg∂2. As a result, performing

ACA tests on the Hg CEMS with Hg∂2

is very difficult. EPA believes it may

need to modify the proposed

performance specification to take this

into account.

Therefore, EPA now believes it is

prudent to have facilities conduct ACA

(i.e., linearity) tests with Hg0 only.

Facilities would then use this ACA to

determine whether the calibration of the

monitor is still valid and, if it fails the

ACA (or if this ACA is the first

performed), use the ACA results as the

basis for a new calibration. Spiking with

Hg∂2 would be done only for the

purposes of ensuring the Hg CEMS

adequately measured Hg∂2. In other

words, the Hg∂2 test would resemble

the NOX converter efficiency test

prevalent for NOX CEMS. In this case a

facility would spike an amount of Hg∂2

within some range (for instance, within

75 to 125% of the emission standard)

and ensure that the measured amount of

Hg reported by the analyzer is within an

acceptable range (for instance, within

±20%) of the actual Hg∂2 spike

determined by the manual method. The

actual ranges will be determined based

on data obtained from these tests. EPA

requests comment on whether this

approach is appropriate.

Dated: March 12, 1997.

Elizabeth Cotsworth,

Acting Director Office of Solid Waste.

[FR Doc. 97–7215 Filed 3–20–97; 8:45 am]

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