AECOM 978.589.3000 tel 

2 Technology Park Drive 978.589.3100 fax 

Westford, MA 01886-3140 

Memorandum 

To enhance and sustain the world’s built, natural and social environments 

To: Scott Bohning Page 1 

cc: Shirley Rivera 

Subject: Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis 

for PHPP 

From: Richard Hamel 

Date: October 7, 2010 

On August 26, 2010, Mr. Scott Bohning of EPA Region 9 provided comments on the 

supplemental information provided in "Palmdale Hybrid Power Project (PHPP) - 

Supplemental Information for the Application for PSD Permit", AECOM, July 21, 2010. 

The following information is provided in response to those comments. The comment is 

reproduced herein with the response following. Figures are provided at the end of this 

memo, and a modeling archive is attached. 

1. There should be documentation on the representativeness of surface 

meteorological data for purposes of analyzing the 1-hr NO2 impacts, including e.g. 

comparison of surface characteristics of the meteorological data station and facility 

site, with some reasoning about how they are sufficiently similar for the data to be 

representative, or about how modeling results using the data would expected to be 

conservative. 

The following information was included in the Class II Area Dispersion Modeling Protocol for 

the Proposed Palmdale Hybrid Power Project, Document 10855-002-040C2MP (ENSR 

Corporation July, 2008), Sections 2.1.4 and 2.2.2: 

The Palmdale Hybrid Power Project (PHPP or Project) modeling used a three-year 

sequential hourly meteorological data set, consistent with general practice for California 

Energy Commission projects. Three years (2002-2004) of surface meteorological data from 

the Automatic Surface Observing System (ASOS) tower at nearby Palmdale Regional Airport 

were used in the application. Per discussion with Bret Banks of the Antelope Valley Air 

Quality Management District (AVAQMD), use of this tower was the preferred option if the 

data were suitable (from a data capture and availability perspective). 
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 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 

Two other sources of meteorological data were considered as alternatives: The 

meteorological tower at the Division Street Monitoring Station in Lancaster, CA, and the 

tower at the William J. Fox Field located north of Lancaster. A data completeness study of 

these locations revealed that the data capture at each of the other towers was lower than the 

data collected at the Palmdale Regional Airport. Palmdale Regional Airport was therefore the 

best option for this analysis because of a) superior data capture, b) its close proximity to the 

Project site (the met tower is 2.5 km [1.5 miles] from the proposed turbine stack locations) 

c) the similarity in surface characteristics between the airport and the Project site, and 

d) AVAQMD’s recommendation that the Palmdale Regional Airport data are the most 

representative for this Project. 

The location of the Palmdale Regional Airport meteorological tower relative to the proposed 

Project location is shown in Figure 1. It is clear from the figure that the proposed Project is 

very close to the meteorological data tower and that the land use at the meteorological tower 

site is consistent with that at the Project site. The wind rose shown in Figure 2 indicates that 

the predominant winds are from the sector between southerly and westerly winds, with a 

peak percentage of southwest winds. The upwind fetch from that direction at the airport 

meteorological site involves more urbanization than the area to the southwest of the Project 

site, but that area near the Project will become more consistent with the area near the 

meteorological tower site after the Project is built, with part of the 1-km circle to the 

southwest occupied by a solar turbine array. 

A copy of the PHPP modeling protocol containing the technical details of the meteorological 

data processing is included in the electronic modeling archive attached to this memo. 

2. There should also be some discussion of the representativeness of the upper air 

meteorological data used. 

Four upper-air data sites were considered for the PHPP PSD application: 

• Mercury-Desert Rock Airport in Mercury, NV; 

• Edwards AFB near North Edwards, CA; 

• Vandenberg AFB in Lompoc, CA; and, 

• The Marine Corps Air Station in Miramar, CA, near San Diego. 

Of these four sites, Edwards AFB is the closest. However, in reviewing the data from this 

site, it was discovered that the data capture at Edwards AFB is very limited, because data 

are only collected during specific United States Air Force activities. Therefore, Edwards AFB 

was removed from consideration because it does not provide an adequate capture rate. Of 

the other three sites, Miramar and Vandenberg were eliminated as the data were not 

representative of Project site because both monitoring stations are close to the ocean and 

have upper air profiles representative of a coastal air mass which is very dissimilar from the 

high-altitude, desert climate of Palmdale. The remaining site – the Desert Rock airport, 

offers very representative data because it is located in a desert setting with similar 
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 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 

 

meteorological characteristics and an expected similar upper air profile to the Palmdale 

project area. Moreover, Desert Rock is typically the site of choice for air studies performed in 

the Mojave Desert region because of its similarity to the conditions present in that area. As a 

result, Mercury-Desert Rock Airport was used in this analysis. 

We also note that the dominant emission source in the study was the PHPP’s emergency 

generator, a low-level source. Hence the upper air profile would have minimal impact on the 

modeling analysis regardless. 

3. There should be additional detail in the assessment of the representativeness or 

conservatism of the background NO2 monitor with respect to background sources. 

 The NO2 memo at p.6 raises the issue of background being "representative of 

allowable emission levels under the existing permits" for the background sources. A 

quantitative comparison of the amount of traffic near the monitor and near the project 

site should be part of the assessment. 

The relative locations of the regionally representative Lancaster Division Street Monitor and 

the PHPP site are shown in Figure 3. The Division Street Monitor is approximately 4.1 km 

[2.5 miles] from the PHPP site, located well within the city limits of Lancaster and within 110 

meters of the Sierra Highway and within 80 meters of the former Southern Pacific rail lines 

that are currently used by the Metrolink Commuter Rail. The Sierra Highway and Metrolink 

rail lines are both almost two kilometers [more than a mile] from the proposed PHPP site. 

The Antelope Valley Freeway (SR-14) is also only about half as far from the Division Street 

Monitor location as it is from the PHPP site (over 4 km [2.6 mile] from the site and about 2 

km [1.2 mile] from the monitor). 

The Antelope Valley Line of the Metrolink Commuter Rail Service, which passes directly by 

the Division Street Monitor and terminates at Lancaster Metrolink Station, runs 24 trains / day 

during weekdays, 12 trains / day on Saturdays, and 6 trains / day on Sunday1

. Because of 

their significantly closer proximity, Metrolink trains passing just to the West of the monitor’s 

location will have a larger impact on the monitor than they would at the PHPP site. 

According to the City of Lancaster Traffic Engineering Division, the daily traffic volume on the 

Sierra Highway is over 20,000 vehicles2

. On an annual basis, this equates to over 5 million 

vehicles (counting only weekdays), and significantly exceeds EPA’s threshold of an annual 

average traffic count of 250,000 vehicles that triggers near-road monitoring3

. The location of 

the monitor within about 50 meters of the Sierra Highway ensures that it is monitoring 

localized elevated NO2 concentrations that are higher (by approximately 30-100 percent)3

than those to be expected near the PHPP site. 

1

 See http://www.metrolinktrains.com/documents/About/Fact_Sheet_2009_10_4Q.pdf. 2

 See http://www.cityoflancasterca.org/Modules/ShowDocument.aspx?documentid=4370. 3

 See EPA’s NO2 NAAQS fact sheet at http://www.epa.gov/air/nitrogenoxides/pdfs/20090722fs.pdf. 

 
AECOM 4

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 

The Division Street Monitor is located on the roof of the Antelope Valley Air Quality 

Management District (AVAQMD) office. In a telephone conversation with Chris Anderson of 

AVAQMD, on September 22nd, 2010, Mr. Anderson stated that NO2 concentrations recorded 

by the monitor visibly spike a few moments after a train passes by. Additionally, Mr. 

Anderson reported that traffic idling at the intersection of Division Street and Avenue K6 

East, directly in front of the AVQAMD offices, causes daily spikes in recorded NO2 levels 

during the morning and afternoon commutes. 

Because of its closer proximity to sources of NO2, such as the Sierra Highway and the 

Metrolink tracks, and the more urban setting around the monitor in general, the monitor 

experiences more local NO2 impacts than the Project site and thus is a conservative 

representation of the ambient NO2 in the area compared with the PHPP site. Furthermore, 

given the proximity of the monitor to the Project site, more distant sources of NO2 can be 

expected to have similar contributions to the ambient NO2 levels at both the monitor and 

Project site. Thus, the Division Street monitor provides a conservative background 

concentration representing both vehicle and train traffic in the local area and the 

contributions of distant sources of NO2 to the ambient concentration of NO2 at the Project 

site. 

Although AECOM considers the monitored concentration to be conservative as background 

for this Project site, additional nearby sources at U.S. Air Force (USAF) Plant 42, as 

discussed in response to comment #4 below, were also included in the cumulative modeling 

analysis. 

4. There does not appear to be any cumulative NO2 analysis including background 

sources, even though the project impact (56.8 ppb) is estimated to be well above the 

draft SIL of 4 ppb. Sources within 50 km beyond the 4 ppb circle around the source 

that result in a "significant concentration gradient in the vicinity of the source” should 

be included in the modeling. The emissions rates for those should reflect the 

recommendations in the Guideline on Air Quality models, section 8.1.2. Note that the 

NO2 memo states that the number of such sources is generally expected to be small. 

To supplement the modeling provided in the Palmdale Hybrid Power Project PSD Application 

– Supplemental Information submitted in July, 2010, additional sources were included in a 

revised cumulative 1-hour NO2 modeling analysis in response to this comment. In a 

telephone conversation with Mr. Chris Anderson of AVAQMD, Mr. Anderson confirmed that 

the two nearby facilities were the only permitted NO2 sources that should be considered for 

cumulative NO2 modeling: Lockheed Martin Aeronautics, and Northrop Grumman, both of 

which are located at USAF Plant 42, adjacent to the proposed PHPP site. 

As was done with the cumulative PM2.5 modeling for the PHPP PSD application, the sources 

at these facilities included in the inventory provided by AVAQMD were reviewed and showed 

that there were a large number of sources, 284 in total, at these facilities. Further review 

showed that the vast majority had very small emissions. Given the large number of sources, 
AECOM 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 

5

 

to simplify the modeling, the AVAQMD was contacted and the following procedure for 

representing the sources was agreed upon and implemented in the modeling: 

• For each facility, all sources that emitted 5% or more of the total emissions of NOX

were included in the model. 

• The remaining source emissions were added to the source that emitted the highest 

percentage of the emissions. 

• In the case where two sources had the highest emissions at the facility, the remaining 

emissions were added to the source closest to the Project site to be conservative. 

This procedure produced a representative mix of source parameters and ensured that all NO2

emissions from the two facilities were included in the modeling. Figure 4 shows the locations 

of the two facilities, their property boundaries4

, and the sources that were included in the 

cumulative modeling. The emissions and source characteristics for each source included in 

the modeling are shown in Table 1. 

The modeling was performed using the same methodology as discussed in section 3.0 of 

the PHPP Supplemental Information submittal, except that the Lockheed Martin and 

Northrop Grumman sources were included in addition to ambient background. Because 

emissions sources cannot contribute to an air quality standard violation on their own 

property, three runs were performed in order to correctly evaluate the modeled impacts: 

1. All sources from PHPP, Lockheed, and Northrop, along with ambient background 

concentrations, on all receptors not located on either Lockheed or Northrop 

property. 

2. All sources from PHPP and Lockheed, along with ambient background 

concentrations, on all receptors located on Northrop property. 

3. All sources from PHPP and Northrop, along with ambient background 

concentrations, on all receptors located on Lockheed property. 

The model was run for both the startup / shutdown and normal operations scenarios with the 

following assumptions: 

a. The emergency generator will not be tested while the combustion turbines are in the 

startup or shutdown process. 

b. The emergency generator and fire pump engine will not be tested simultaneously. 

4

 Figure 4 shows the boundaries of these two facilities, but we note that both facilities are located 

within the entire USAF Plant 42 area which is a fenced, secure area that is restricted to the public, and 

would not be considered to be “ambient air.” 
AECOM 

Table 1: Lockheed Martin and Northrop Grumman Sources Parameters Volume Sources: 

Source ID Facility 

UTM 

Easting 

(NAD27) 

UTM 

Northing 

(NAD27) 

Base 

Elev. 

(m) 

Rel. Hgt. 

(m) Sigma-Y Sigma-Z 

S045 Lockheed 397820.6 3830906.0 746.76 3.552 35.034 6.979 2S046 Lockheed 400409.6 3833159.0 746.76 2.302 28.268 6.979 1S050 Lockheed 397820.6 3830906.0 746.76 3.552 35.034 4.652 2S051 Lockheed 400409.6 3833159.0 746.76 2.287 28.268 4.652 1S052 Lockheed 399963.6 3831599.0 746.76 2.302 4.284 4.652 2S158 Northrop 401777.9 3833322.0 789.30 12.195 2.841 5.672 9

Point Sources: 

Source ID Facility 

UTM 

Easting 

(NAD27) 

UTM 

Northing 

(NAD27) 

Base 

Elev. 

(m) 

Stack 

Hgt. 

(m) 

Temp 

(°K) 

Exit 

Vel. 

(m/s) 

Exit. 

Diam. 

(m) 

S230 Northrop 402337.0 3833310.0 789.30 12.195 299.817 0.102 3.049 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 7

The results of the three modeling cases were then processed using the “Post-1hr” postprocessor created by AECOM and described in section 3.2 of the PHPP Supplemental 

Information submittal, and the worst case impact was compared to the standard. The 

results, as shown in Table 2, demonstrate that the worst case impact occurs during normal 

operations when the emergency diesel generator is being tested. The modeled impact of 

PHPP sources, Lockheed Martin and Northrop Grumman sources, and ambient background 

is 184.1 μg/m3

. As this is below the 1-hour NAAQS for NO2 (188 μg/m3), compliance with the 

standard is demonstrated. 

All files associated with the cumulative 1-hour NO2 modeling analysis are included in the 

electronic files archive attached to this document. 

Table 2: Cumulative 1-hour NO2 Modeling Results 

Modeled Concentrations (μg/m3

) 

Case All 

Sources

Northrop 

Property 

Lockheed 

Property Max % of Standard

Normal Operations - 10% - No Emgen 115.2 108.7 112.2 115.2 61.3% 

Normal Operations - 10% - No Fire 

Water Pump 184.1 123.1 176.2 184.1 97.9% 

Startup/Shutdown - 40% - No Emgen 148.6 108.7 151.2 151.2 80.4% 

5. It is not clear that the hour by hour addition of modeled to monitored values 

provides a conservative estimate of impacts that could occur, since in future years 

values may line up differently (e.g. the highest monitored and modeled values could 

occur simultaneously). The NO2 memo at p.5 states that "some level of temporal 

pairing of modeled and monitored values may be considered on a case-by-case basis, 

with adequate justification and documentation". There should be some showing that 

the hourly method used, along with choice of background site, results in a 

conservative estimate of total impacts relative to the NAAQS. 

As discussed in the response to comment #3, the addition of ambient background data from 

the Lancaster Division Street monitor is a conservative measure for the following reasons: 

• More urban location of the monitor. 

• Closer proximity of the monitor to the Antelope Valley Freeway, Sierra Highway, 

Metrolink rail line, and commute related traffic congestion on Division Street, the latter 

two of which have an observed effect on background NO2 concentrations according 

to Mr. Chris Anderson of the AVAQMD. 

• The likelihood that some of the monitored background comes from Lockheed and 

Northrop emission sources, meaning that those emissions are being double counted 

in the modeling analysis. 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 8

An additional level of conservatism to the modeling is the assumption of constant and 

concurrent emissions at the maximum potential to emit amongst all sources, Project and 

non-Project, included in the modeling. 

The use of time matched backgrounds more accurately couples the amount of NO2 in the 

atmosphere associated with the specific meteorological conditions occurring at the time. As 

Project impacts are derived from those same meteorological conditions in the modeling, the 

relative impacts of the Project and the ambient concentrations are representations of the 

specific meteorological conditions being modeled, and therefore are more accurately 

combined using time-matched background. Additionally, due to the large number of ongoing 

programs to lower NO2 emissions, such as the tightening of the 1-hour NO2 CAAQS in 

February, 2007, which post-dates the time matched ambient background used in this 

analysis, as well as the new Federal 1-hour NO2 standard, local AVAQMD NOx control rules, 

and California and federal vehicle emission standards and air toxic control measures, future 

ambient background concentrations should continue to go down. A review of the maximum 

recorded concentrations at the Division Street Monitor shows that the ambient background 

concentrations have gone down every year since 2004, the last year included in this study. 

The maximum background concentration recorded in 2008, the last year currently available 

on the EPA’s AIRS website5

 was 0.061 ppm, a value 40% lower than the 2004 maximum 

ambient concentration of 0.103 ppm. As a result, the use of background data from 2002-

2004 is another significant measure of conservatism build into the analysis. 

6. The NO2 memo specifically notes at pages 3 and 9 that the there is no default instack NO2/NOx ratio for either the OLM or PVMRM methods for the 1-hr NO2 NAAQS. 

 Rather (p.4), there should be a "case-by-case determination based on an assessment 

of the adequacy of the ozone titration mechanism utilized by these options to account 

for NOx chemistry within the AERMOD model based on 'the chemical environment into 

which the source’s plume is to be emitted' (Appendix W, Section 5.1.j)." 

In the cumulative analysis performed in response to comment #4, a GE-supported in-stack 

NOX / NO2 ratio of 10% (consistent with the default value) was used for normal operations, 

while 40% was used for startup / shutdown. Both ratios are likely conservative 

representations of the true conversion rate as described below: 

Normal Operations 

In an email exchange on 9/20/10 with Andrew Dicke, HDGT Environmental Product 

Marketing Manager from GE Power and Water, Mr. Dicke indicated the following is GE’s 

recommended guidance regarding the in-stack ratio for GE7FA turbines during normal 

operations: 

“Suggested NO2/NO emission assumptions: 

• Assume NO2 ranges from approximately 10 to 15% of the total NOx when operating 

within the emission compliance range (approximately 50% to 100% of base load). 

 

5

 http://www.epa.gov/air/data/geosel.html 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 9

• If there is an SCR, assume the NO2 is extremely low (<1% of total NOx). SCRs react 

with NO2 more rapidly than NO, as such the NO2 percentage is very low downstream 

of the SCR.” 

PHPP will use two GE7FA turbines, configured with GE’s Rapid Start Process (RSP). The 

turbines will be equipped with SCR. Although the above GE email indicates the ratio should 

be well below 10% when an SCR is used, 10% was used as the in-stack ratio for the two 

turbines for normal operations. Because the turbines will be using SCR during normal 

operations and GE has found the turbines will typically have an in-stack ratio at or below 1%, 

the use of 10% as the in-stack ratio is a conservative measure in the analysis. 

Startup / Shutdown 

As documented in the PSD application, the shutdown mode was determined to produce 

higher emissions than found during startup, and a shutdown was therefore used to represent 

the worst case startup / shutdown scenario. Mr. Dicke of GE did not provide a specific 

recommendation for an in-stack ratio during startup and shutdown, although he agreed that 

the ratio could be higher than during normal operations. The only other data found by 

AECOM for similar gas turbines was information determined during stack testing done at the 

Palomar Energy Center on May 3rd, 4th, 18th, and 23rd, 2006. Based on that data, the San 

Diego County Air Pollution Control District (SDAPCD) recommended the use of a 40% instack ratio during startup. Additional testing performed later specifically during a cold-start 

scenario determined the in-stack ratio of NOX to NO2 to be 5% rather than 40%. SDAPCD 

chose to retain their conservative recommendation of 40% despite this result. Because 

additional data on the in-stack ratio during startup / shutdown is sparse, AECOM used the 

SDAPCD suggested value of 40% for the revised PHPP cumulative modeling. This 

assumption is very conservative for several reasons: 

1. The Palomar Energy Center test specifically focused on startup showed a ratio of 5% 

during a worst case (cold start) scenario. 

2. The PHPP will utilize RSP, in which the turbines will be brought to the normal 

operating temperatures (and hence stack tip ratios) much more quickly. 

3. In the shutdown case being modeled for PHPP: 

a. Unlike the beginning of startup, the turbines would be hot, and therefore the 

ratio of NOX to NO2 at the stack tip would be at or near the same value as for 

normal operations. 

b. For at least some of the shutdown, the SCR will still be online, and even after 

it is offline, the residual ammonia continues to react with the NO2. 

c. Using 40% for the in-stack ratio assumes that the shutdown process takes the 

full hour. In reality, the shutdown process takes less than 30 minutes. During 

the other 30 minutes of the hour the turbines would be at normal operation 

levels (with a lower in-stack ratio) with SCR. As a result, using 40% for the 

whole hour is equivalent to an in-stack ratio of 70% or more during the actual 

shutdown period. 

d. The in-stack ratio during the actual shutdown period itself would be transient: 

for the first portion of the shutdown, the in-stack ratio would be similar to 

normal operations because the turbine would still be hot and the SCR would 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 10

still be operating. Only toward the end of the shutdown would the ratio of NOX

to NO2 potentially increase, when the NOx emission rate is trending toward 

zero. Thus, even the assumption of a higher in-stack ratio during the whole 

duration of the actual shutdown is conservative. 

e. The same stack parameters for low load operation were assumed to be 

constant during the hours, when they would actually be changing and the 

point of maximum impact would be moving throughout the hour. 

For the reasons given above, the assumption of a 40% in-stack tip NOX to NO2 ratio is 

conservative, perhaps to a large degree. Additionally, the modeling conservatively assumes 

that both turbines are being shutdown simultaneously, the worst case shutdown scenario. 

As a result, not only are the selections of 10% and 40% NOX / NO2 stack tip ratio likely 

conservative, there are several other significant levels of conservatism built into the modeling 

beyond the ratios assumed. 

7. There should be some discussion of the representativeness of the Lancaster site 

for providing ozone data for use with OLM. 

Ozone is largely a regional pollutant. Therefore the primary factor in deciding the 

representativeness of a monitor for use in a modeling analysis is its proximity to the Project 

site. Because the monitor is less than 2.5 km [1.5 miles] from the PHPP site, and because, 

as demonstrated in the response to comment #3, the monitor is located such that the 

recorded concentrations of pollutants should be as high or worse than at the project site, the 

Division Street monitor should be a representative, or potentially conservative, source of 

ozone data for the analysis. 

8. If there is any missing data from the chosen ozone site, then the procedures used 

for filling in missing data should be described, and shown not to bias the modeling 

results low.

Over the 3 years included in the modeling analysis (2002-2004), ozone data were available 

at the Lancaster Division Street Monitor for 24,113 hours out of a total of 26,304, or 91.7% of 

the total hours. The remaining hours were filled using the average ozone background over 

the available 24,113 hours, which was 38.8 ppb. Of the missing hours, 1096 occur at 

midnight when the monitor is off line for auto-calibration. On many occasions autocalibration took two hours, accounting for the vast majority of the remaining 1095 missing 

hours. As night time levels of ozone are usually considerably lower than during the day, the 

use of the average ozone concentration to fill these values is a conservative measure, by up 

to as much as a factor of ten at times. In addition, the fact that the hours that are missing 

are those that would typically have the lowest concentrations artificially increases the 

average value used to fill the limited number of daytime missing hours upward. As a result, 

the use of 38.8 ppb to fill the missing hours is a conservative measure that thus should, if 

anything, bias the results higher rather than lower. 

Please feel free to call me at 978-589-3275 if you have any questions or comments 

regarding this information.

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 11

Figure 1: Relative Location of the PHPP Site and Meteorological Data Tower 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
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Figure 2: Wind Rose for Palmdale Regional Airport (2002-2004) 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 13

Figure 3: Relative Location of the PHPP Site and the Division Street Monitor 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 
AECOM 

 Response to EPA Comments on AECOM 1-hour NO2 NAAQS Analysis for PHPP 

14

Figure 4: Location of Lockheed-Martin and Northrop-Grumman Sources and Property