From: "Ziman, Steve -" <SDZI@chevron.com>

To: RTP3.RTMU540(SANDERS-DAVE),RTPMAINHUB.INTERNET("dc...

Date: 11/7/96 1:14pm

Subject: issue paper for STSWG on attainment feas

FROM: Ziman, Steve -SDZI

DATE: 11/07/96 09:56

TO: OPEN ADDRESSING SERVI-OPENADDR

CC:

SUBJECT: issue paper for STSWG on attainment feas

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Issue Title: Is attainment of an 8 hour 8 pphm ozone standard practical and

feasible (Draft-for discussion by STSWG)

Contact: Steve Ziman, Chevron Research and Technology Company, (510-242-1530-

phone; 510-242-5947-fax; sdzi@chevron.com)

Date November 7 1996

I. Background:

EPA is proposing to implement a new ozone standard based on an 8 hour

averaging period. The form of the standard will be the three year mean of

the third highest concentration with either 8.5 pphm or 8.1 pphm being the

cut point for nonattainment designation, based on preliminary reports. As

part of the phase II efforts of the FACA Subcommittee and its workgroups,

policies are being developed for implementation of the new standard. These

policies may be assuming that the new standard can be attained by all

nonattainment areas throughout the country. The present implementation

policy and regulations explicitly adhere to the supposition that the one hour

12 pphm standard is attainable.

If the assumption about feasibility of attainment is not an appropriate one,

based on technical analyses, then it is very important that this information

be conveyed to those work groups and the Subcommittee prior to finalizing any

decisions on specific implementation issues. With this information available,

these groups can decide on how it can be factored into other issues which are

now being discussed within those groups.

II. Technical Analyses Relevant to the Question of Feasibility of Attaining:

a. Analysis of the AIRS data base indicates that reduction of peak one hour

ozone concentrations has less impact on attaining an 8 hour standard for many

areas of the country. Put another way, while there has been significant

progress in many areas in lowering the peak values, those reductions are not

as readily seen for an 8 hour standard. This suggests that the strategies

that have been pursued for the one hour standard will have much less effect

on the underlying, baseline ozone concentrations (as may be seen in the

results of the analysis described in b). Consequently, compared to the one

hour standard, an 8 hour standard may be more difficult to attain since

significantly more reduction is required to lower the baseline. Further,

analysis of the 1993-1995 data base for all areas which have 8 hour values

above 8.5 pphm indicate that those areas which have at least 4 hours between

8 pphm and 9 pphm may not be able to attain the standard. Depending on the

form (third, fifth highest concentration), up to 50% of all potential

nonattainment areas fall into this category. These areas will need

sufficient reductions to lower the baseline, and these reductions will be

much greater than those needed for the peak shaving. The Chock analyses

suggest that the actual goal of an attainment strategy be set at 7 + pphm for

the 8 hour standard. There are some very important complicating factors.

The first is that background concentrations for clean air areas for 8 hour

concentrations can be greater than 6 pphm. The second is that with the very

tight distribution of values between 8 and 9 pphm, it is expected that areas

will bounce in an out of attainment unless reductions can be achieved to

approach the 8 hour average of 7 pphm.

b. As part of an effort to estimate the costs associated with the above

proposed ozone standard (using the 8.5 pphm cut point), modeling was done to

estimate the amount of reductions necessary beyond those needed for the

present one hour ozone standard for two areas of the country. The areas, the

San Francisco Bay Area and the Lower Lake Michigan area were chosen because

Photochemical modeling had been performed by the respective agencies for

each of these areas to determine the emissions reductions needed for

attainment of the federal one hour ozone standard.

The data bases used for the model simulations were derived from intensive

data collection efforts. The LMOS program provided the data for the UAM-V

modeling performed by LADCO. The BAAQMD September 1989 intensive ozone study

provided the data for the UAM-IV study done by BAAQMD. Note that the LMOS

work is now being used as one of the episodes for the OTAG effort.

Base year and future year emissions inventories for both area were

available or could be developed with input from the respective agency

The Bay Area simulations represented an area that was minimally affected by

upwind transport, and therefore should provide a lower bounds estimate of

emissions reductions needed for attainment. The Lower Lake Michigan area was

affected by transport, and its modeled peak value was 16.4 pphm (over Lake

Michigan) for the 26th of June, 1991. However, compared with other severe

areas, its one hour design value is one of the lowest based on recent data.

Analyses showed that episodes modeled were also typical of 8 hour ozone

episodes

both episodes modeled were shown, through data analysis to be about the 3rd

highest concentration episodes.

Modeling was done for the attainment of the one hour standard to show that

the same results were achieved as those that the agencies got. The outputs

were then converted to 8 hour averages to determine the 8 hour modeling

design values which provide the starting point for determining what

additional reductions are needed. A series of twenty simulations were done

with combinations of across the board percent reductions of hydrocarbons and

NOx from the basecase. This set of simulations was used to develop ozone

isopleths for the peak site and a number of geographically diverse monitoring

sites. The analysis of the isopleths for each of the two areas allowed:

The information needed to choose an appropriate control strategy; in the

case of the Bay Area, the 8 hour isopleths supported previous findings of the

one hour simulations that the area is hydrocarbon limited. For the Lower

Lake Michigan area, the results suggest that depending on location,

hydrocarbon reduction or NOx reduction was preferable. A hydrocarbon

approach was taken as it was the most preferable on whole.

The information also allowed for a determination of the percent reduction

needed to attain an 8 hour standard.. For both areas, these reductions are

those required beyond attainment of the present one hour standard. For the

Bay Area, 20% hydrocarbon reduction was estimated as necessary to attain.

For the Lower Lake Michigan area, a 90% reduction was estimated (had a NOx

strategy been pursued, similar reductions would have been required)..

Analysis of all available control measures, including those identified in

some of the most stringent SIPs and FIPs nationwide, could only identify

about one half of the reductions needed for the Lower Lake Michigan Area. A

cap of $ 30,000 per ton was used as an upper limit on cost. These measures

included stationary and area source controls, mobile source and

transportation mitigation measures. It is very important to note that in the

course of estimating the needed reductions, the upwind boundary conditions

were reduced proportional to the reductions in the modeling region until the

upwind boundary was essentially equivalent to conditions observed in clean

areas of the US. Thus, the emissions reductions needed within the Lower

Lake Michigan region were not compensating for upwind conditions.

III. Implications of Results:

The Lower Lake Michigan area, particularly the Chicago CMSA, was classified

as a severe area. However, review of both the frequency and intensity of the

episodes over the past few years shows that it should have a much better

chance of attaining the present one hour ozone standard than many of the

other severe areas. Houston, for instance, continues to have multiple

exceedances of the one hour standard at levels above 18 pphm. Certain areas

in the northeast corridor also continue to see ozone levels well above the

standard. Some of these areas have already adopted many of the stringent

controls that have previously been implemented in Los Angeles; yet they still

can not show via modeling that the projected reductions will result in

attainment. Further, based on estimates of the an 8 hour 8.5 pphm design

values for many of these areas, it is not clear that the level of reduction

beyond that needed for the present one hour standard can be identified, or

even approached. For example, based on 1993-1995 data, the 8 hour ( 8.5 pphm)

design value for a 3rd highest concentration for the severe areas are:

1. Baltimore 11.7 pphm

2. Chicago, Il-In-Wis CMSA 9.7 pphm

3. Houston CMSA 11.9 pphm

4. Milwaukee CMSA 10.4 pphm

5. Muskegon 10.0 pphm

6. New York, NJ-CT CMSA 11.3 pphm

7. Philadephia, NJ-De CMSA 11.1 pphm

8. San Diego 11.2 pphm

Further, if areas must plan to reduce ozone levels well below an 8 pphm value

in order to limit the probability of bouncing out of attainment, these

reductions will be approaching the background levels measured in clean

areas .

If this is indeed the case, then requirements for attainment of a new

standard are practically infeasible in the foreseeable future, assuming that

attainment will still rely on reducing the peak monitor to meet the form of

the new standard. From the technical perspective, this suggests that any

policy discussions of setting of attainment dates may not be realistic.

IV. Recommendations:

There are a number of modeling studies being carried out now to meet the

requirements of the 1994 ozone demonstration SIPs. Where possible, the

relevant agencies should be reviewing this modeling to determine the percent

emissions reductions needed to achieve an 8 hour 8.5 pphm three year mean of

the third highest concentration. The findings of the Lower Lake Michigan

study, and any others now available should be made available to the other

workgroups and the Subcommittee prior to final decisions on relevant policy

issues.