**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**REGION III**

**1650 Arch Street**

**Philadelphia, Pennsylvania 19103**

**DATE:** June 23, 2008

**SUBJECT:** Technical Support Document for the Notice of Proposed
Rulemaking -- Delaware; Control of Stationary Combustion Turbine
Electric Generating Unit Emissions

**FROM:** Gerallyn Duke, Environmental Scientist */s/*

Office of Enforcement and Permits Review

**TO:** File

**THRU:** Cristina Fernandez, Chief */s/*

Air Quality Planning Branch

**A. BACKGROUND**

Delaware Department of Natural Resources and Environmental Control
(DNREC) has identified large stationary combustion turbines ("CTs") as
significant contributors to the release of nitrogen oxides (NOx), which
is a precursor to the formation of ground-level ozone. Ozone poses a
significant threat to human health especially to the young, the elderly
or anyone with impaired ability to breathe, as ozone harms the lungs.

CTs normally operate at peak times for the demand for electricity. In
Delaware, peak times are in the summer and coincide with hot and humid
weather conditions that are conducive to the formation of ozone. By
reducing NOx emissions from CTs during the ozone season, the likelihood
that Delaware's air quality will exceed the federal standards for ozone
is reduced. This regulation will affect six existing CTs in Delaware,
each with an installed capacity of 1 megawatt, none of which currently
operate with any NOx pollution control equipment.

These six CTs emitted 2.21 tons of NOx per day in 2002, which is the
most recent year for Delaware's emissions inventory. DNREC has
determined that use of water injection technology would reduce NOx
emissions by approximately 40 percent, or by 0.88 tons per day. Water
injection reduces the combustion temperature and consequently reduces
NOx emissions.

On October 6, 2005, DNREC opened the proposed rulemaking proceeding in
Start Action Notice 2005-10 to regulate and reduce the air emission of
NOx from certain CTs used for electric generation. DNREC published the
proposed regulation, "Control of Stationary Turbine Electric Generating
Unit Emissions," on April 1, 2007 in the *Delaware Register of
Regulations* and held a public hearing on April 26, 2007. The public
comment period for participants at the public hearing was extended until
May 9, 2007. The Hearing Officer's Report, dated June 15, 2007 responds
to the comments received. Minor changes to the proposed regulatory
language were made in response to comments received.

Secretary's Order No. 2007-A-0023, dated June 19, 2007, approves Final
Regulation, 7 DE Admin. Code 1148, "Control of Stationary Combustion
Turbine Electric Generating Unit Emissions" in Delaware. The effective
date is July 11, 2007.

**B. EPA REQUIREMENTS**

Delaware is part of the Philadelphia-Wilmington-Atlantic City ozone
nonattainment area and it must take regulatory actions to improve air
quality to meet the 8-Hour Ozone National Ambient Air Quality Standard
(NAAQS) by 2010. This regulation is one of many regulatory actions the
Department has undertaken in recent years as part of its State
Implementation Plan (SIP) which is a federal requirement to show that
Delaware's air quality will attain compliance with NAAQS by 2010. No
inconsistencies or inadequacies regarding EPA policy and the Clean Air
Act have been identified.

**C. SUMMARY OF SIP REVISION:**

This regulation requires that an owner or operator of an existing
stationary combustion turbine electric generating unit located in
Delaware with a base-load nameplate capacity of 1 MW or greater must, by
May 1, 2009, either demonstrate that the existing stationary combustion
turbine generating unit meets the emission limits listed below or must
install NOx emission controls designed to meet these limits:

> ▫ For CTs that burn gaseous fuel -- 42 parts per million volume,
> corrected to 15 percent O~2~ dry basis (ppmv) NOx

▫ For CTs that burn liquid fuel -- 88 ppmv NOx.

Design of these limits was based on anticipated NOx emissions if water
injection pollution control equipment were installed.

The six CTs affected by this regulation operate without any NOx
pollution control equipment, although they are subject to regulations
designed to control NOx emissions. DNREC determined that the six sources
could achieve significant reductions in their NOx emissions through the
use of water injection equipment. EPA has previously recognized this
equipment and technology as reasonably available control technology
(RACT). Water injection is a proven, feasible technology that has been
used in other states to reduce NOx emissions.

Owners or operators of covered units installing NOx emission reduction
controls are required to submit an emissions control plan which details
all actions to be taken to comply with the NOx emission limits set forth
in this regulation. These plans are due to DNREC for approval no later
than April 11, 2008. Compliance testing also is required for all units
covered by this regulation. Finally the owners or operators of covered
units must submit for approval a monitoring plan, maintain an operating
log during the ozone season, and submit required monitoring information
to DNREC on an annual basis. These requirements ensure that the NOx
limits may be enforced.

D.  **EVALUATION OF STATE SUBMITTAL**

DNREC calculates that the above emission limits would reduce NOx
emissions from CTs by 40 percent, or by 0.88 tons per day to
approximately 1.33 tons per day. Such a reduction would significantly
improve air quality, particularly on days when CTs normally operate,
i.e., hot humid days and when weather conditions are conducive to
forming ground-level ozone. Such an improvement is one of the many
regulatory steps taken to meet the NAAQS. DNREC maintains that this
regulation will allow DNREC to fulfill Delaware's federal regulatory
responsibility to attain the NAAQS by 2010.

On September 11, 2007, Delaware submitted a letter notifying EPA of its
revision to the SIP for Ozone by adopting Regulation No 1148 -- Control
of Stationary Combustion Turbine Electric Generating Unit Emissions. The
submittal included a certification that a public hearing was held in
accordance with notice required by 40 CFR 51.102, affidavit of
publication of the announcement of the public meeting for the proposed
regulations in *The News Journal* and *The Delaware State News*, the
Hearing Officer's Report on the proposed regulation and public comments
received, DNREC's Response Document to Comments Submitted on the
Proposed Adoption of Regulation No 1148, a copy of the final
regulations, and a copy of the Secretary's Order No. 2007-A-0023 which
approves the final regulations. EPA believes the state's supporting
materials are technically adequate. As discussed above, under this
revised SIP, six CTs are expected to install water injection technology
by May 1, 2009.

This regulation is not expected to impact potential growth in the
affected area. This regulation does not apply to new generating units
which might otherwise impact potential growth. Also, because CTs
generally are expensive to operate, these units are not expected to
operate more frequently than during peak periods of demand for
electricity.

The regulation is expected to result in reduced NOx emissions from
significant sources of such emissions which have not installed emission
controls under other air quality regulations.

**E. CONCLUSIONS AND RECOMMENDED AGENCY ACTION:**

The SIP revision strengthens the Delaware SIP and is recommended for
approval.