Appendix A shows the PMio concentration isopleths experienced
within the study region. Figures A-1 through A-2 0 show the
isopleths for each individual sampling day. Figure A-21 gives the average concentration isopleth for the region during the entire 20 day study. The values shown in Figure A-21 represent the average normalized values over the study period. These normalized values are obtained by dividing the concentration reading at a particular location by the average concentration measurement for all monitor sites for a particular day. These normalized values are averaged for each site based on the number of successful sampling days at that site. This procedure avoids any bias resulting from days when no valid samples were collected. If a monitor did not run on days with high pollutant levels, that site may show a low overall average concentration even if it consistently measured higher than average values on the lower reading days. Therefore, the
normalized concentration values provide relative readings at each site which reduces bias based on the pollutant's temporal
TABLE 5-1 MONITOR
SITE DESCRIPTIONS |
SITE CITY LOCATION DESCRIPTION
NO.
1 North Bergen Paterson Plank located at the 1
Rd. intersection of Columbia
Ave., 100 yards from the 1-495 overpass of Paterson
Plank Rd. and Tonnelle
Ave.
2* North Bergen J.F. Kennedy located on the eastern i
1
Blvd.** edge of a frequently empty parking lot near the 31st
St. intersection. 1-495
is 300 feet to the south. |
1 3*
Weehawken Boulevard East tunnel tollbooths.100 feet northeast of theLocated near the Port
Authority Admin. Building. [
4 Union City New York Ave. located at the 15th St.
intersection within a
residential area. [
5^ Weehawken Hackensack east of Hackensack Water•s
Plank Rd. Reservoir No. 2. Located
200 yards southwest of the tunnel entrance.
6 Union City J.F. Kennedy located between 37th and
Blvd. 38th Streets in a
residential area. ||
T Union City Health Dept. site of the permanent
Building NAAQS PMjo monitor site.
Located on the roof of a 2
story building. ||
8 Union City Kerrigan Ave. located between 19th and
20th Streets in a i
residential area. |
9 Weehawken Boulevard East located at the
intersection of 31st St.
on the eastern end of a
small (25 spaces) commuter
parking lot. The 1-495
overpass is 100 feet to
the north while the ramp
"* from 1-495 west is 30 feet
40
TABLE 5-1 MONITOR SITE DESCRIPTIONS (cont) \
10^ Union City Central Ave. located at the 14th St.
intersection next to a 3
story church building. 11 Union City Palisade Ave. located at the 27th St.
intersection in a residential area.
12 Union City West Ave. located at the 25th St.
intersection next to a
small restaurant. A nightclub is located on the opposite corner. * Monitors are collocated at these sites
'' The original location for site 2 was inaccessible because
the roadway in the area had been blocked off and rerouted. Therefore, the final site selected was based
on the location within a grid which had the highest
correlation coefficient with the original location and was accessible by car.
'ͣ Sites did not conform to the general siting criteria
established in the CFR.
5.5 Data Quality
5.5.1 Sample Collection
Total valid data capture for the study was slightly below 90% (31 samples deemed invalid out of 300 samples taken). Table 5-2
lists the reasons samples were invalidated, as well as the number of samples affected in each category. Over 50% of the invalidated samples resulted from the inaccessibility of the monitors at site 7 during the weekends and holidays. When these samples are not considered in the data capture analysis, almost 95% of the samples are valid. Monitor failure only accounted for 16% of the invalid
TABLE 5-2 |
ERROR DESCRIPTION NUMBER OF
SAMPLES
INVALIDATED
PERCENT INVALIDATED
Site 7 not accessible 16 51.6
Monitor not set correctly (operator
error)
8 25.8
Monitor Failure (low battery
indication)
5 16.1
Filter Damaged (operator error) 2 6.5
TOTAL 31 100.0
5.5.2 Analytical Precision
Three types of control filters established the analytical precision of the study: unexposed lab blanks, unexposed field
blanks and exposed field blanks. Unexposed lab blanks were filters
which remained in a controlled environment except for being weighed at the beginning and end of a sampling day. These filters provide
information on the precision of the weighing technique. Unexposed
field blanks were loaded in the monitor inlets, placed in plastic
bags and carried into the field, but were never attached to the
samplers. These filters indicate any damage which occurred to the
filters as they were loaded and unloaded into the inlets. Exposed
field blanks underwent the same treatment as the unexposed field
blanks but were also attached to the monitors and placed in the field although the monitors were not run. These filters represent the amount of contamination which occurred while the monitors did not run (such as the four hours each day when the inlets were being
42
replaced). Thus, analytical precision is estimated from
reweighings of the three types of blank filters, and is given in
Table 5-3.
The maximum weighing difference experienced during the study
was 0.029 mg which occurred on an exposed filter. This difference corresponds to a concentration of less than 5 fig/m^ under typical
operating conditions (20 hour sampling at 5 1pm). The average
difference on exposed filters of 0.013 mg corresponds to a concentration of only 2.17 iiq/v:?. Neither the lab or field blanks showed a substantial inconsistency in measurements. Thus, the
overall analytical precision for the project is good. A surprising
result was the lack of negative differences in the blanks. One reason may be that the filters were not weighed in a controlled
environment, only stored in one. However, all differences were
small and deemed insignificant. For more information on the
analytical procedures used for the experiment. Appendix F should be
consulted.
TABLE 5-3
FILTER BLANKS EXPOSED
FILTERS LAB FIELD 1 Number of Samples 40 40 « Average Diff. 0.005 0.007 0.013 Std. Deviation 0.004 0.005 0.008 Maximum Diff. 0.015 0.018 0.029
1 Minimum Diff.
0.000 0.000 0.0055.5.3 Monitor Performance
5.5.3.1 Study Design
As previously mentioned, monitors were located at 12 separate
sites throughout a 2 km X 2 km study area. The site identification
number represented the expected concentration level at that site (based on dispersion modeling) compared with the other sites.
Thus, the highest expected pollutant concentration should occur at
site 1 and the lowest concentration at site 12. For each of the twenty sampling days, the monitors ran for 20 hours, from 10 a.m. until 2 p.m. of the following day. After the removal of a sample
from a monitor, the location of that monitor changed to the next site. Thus, after collecting the sample at one site, the monitor
from this site moved to the next site. The monitor at this new
site then transferred to another site, and so on. Therefore, each
monitor had a theoretically equal chance to be sited at each sampling location during the study.
To ensure the monitors performed adequately in the field, flow rates were checked before and after sampling with a bubble flowmeter (Mini-Buck Calibrator, 0-3 0 1pm). As seen in Appendix B, the maximum flow measured was 5.18 1pm while the minimum flow was recorded at 4.67 1pm. Thus, all samplers consistently had flow
rates well within + 10% of 5 1pm as recommended in the Operations
Manual (LRAPA, 1992).
To determine any sampling bias by the LRAPA monitors during
the study, two comparisons are presented. First, tests were conducted at the EPA facilities in Research Triangle Park, N.C. to
44
establish the performance characteristics and reliability of the
monitors prior to the field study. Two tests were run with all
available monitors collocated such that all inlets were a minimum
of 1 meter apart, thus ensuring all monitors sampled the same
ambient aerosol concentration. Table 5-4 shows the results of
these tests. Second, the concentration values obtained from the field study at each site for the collocated monitors is compared. Figures 5-1, 5-2 and 5-3 show the results for site 2, 3 and 7, respectively. For the figures, locations a and b at the collocated
sites were determined before the study began.
Finally, a study performed in Research Triangle Park, N.C. followed the Weehawken, NJ field study to determine the LRAPA
samplers performance compared to reference high volume samplers.
For this study, two LRAPA monitors were collocated with two
reference samplers. One reference sampler had a Wedding PMjo size
selective inlet while the other had an Andersen-Sierra PMjq size
selective inlet. Two meters separated the reference samplers while
the LRAPA monitors were located approximately 1.5 meters from each of the reference samplers. All monitors sampled for 23 hours each
day. The LRAPA monitors ran at the recommended 5 1pm while the
high volume samplers ran at 40 cfm. Average daily wind speeds
during the study varied from 0.83 m/s to 2.57 m/s. Figure 5-4 shows the results from this study.
5.5.3.2 Study Results
Table 5-4 presents the results of the preliminary performance
study done at the Research Triangle Park, NC facilities. The
monitors provided comparable readings for this study, with only
monitors 70, 91 and 409 showing a very slight high sampling bias. For the field study in Weehawken, NJ, the monitors performed consistently throughout the study. As shown in Table 5-2, only 16% of the invalidated samples were the result of monitor failure.
Also, Figures 5-1 through 5-3 demonstrate that most of the
collocated monitors provided similar concentration readings. No monitor regularly sampled higher or lower PM,o concentrations
throughout the study. Of the 50 successful collocated samples
taken during the study, over 10% of the monitors produced equivalent concentration values while 90% showed no more than a 5
/xg/m' difference between samples. Based on these results, the
samplers seemed to perform well under both high and low pollutant loading conditions.
The results of the field study also seem to indicate that
LRAPA monitor readings were comparable to the actual particulate concentrations in the area based on the results from the NAAQS permanent monitor located at site 7. Table 5-5 shows the concentration values read by the NAAQS monitor. This monitor ran
for 24 hours every sixth day from midnight to midnight. Therefore,
the concentration values are not directly comparable. Also, some
of the sampling days for this monitor occurred on weekends when
46
1 TABLE 5-4 -
MONITOR EVALUATION (at EPA Facilities)
MONITOR
1 NUMBER
TEST 1 Ambient Concentration TEST 2 Ambient Concentration {/xg/m')1 ^^
30 24 60 34 32 63 28 37 68 27 38 70 3134 1
71 ** 24 73 28 35 86 ** 29 91 29 35 93 28 331 408
23 37 409 29 33 410 28 35 AVERAGE 28.68 32.82 STD. DEV. 2.72 4.49 ** MonitorsMonitors
71 and 86 were not run during this test.
64, 67 and 72 were unavailable for this study.
Because concentration readings could not be directly compared
to the reference monitor at site 7, the separate study measuring
the two types of monitors was performed in North Carolina. As can
be seen in Figure 5-4, the LRAPA monitors showed the same general
trend in concentration readings but consistently underestimated the
actual values. Since wind speeds were low during the study, local
weather effects were probably not an influence on the study
FIGURE 5-1
MONITOR COMPARISON
Collocated Data - Site 2 E 80- ?70- O-H----r 123456789 10 1112 13 14 15 16 17 18 19 20 DAY Location a —•- Location b FIGURE 5-2
MONITOR COMPARISON
Collocated Data - Site 3
T---1---r-
23456789 10 1112 13 14 15 16 17 18 19 20
DAY
48 FIGURE 5-3 ^-90 E 80 §"70 60 50 40 30 o <->20 o I 0
MONITOR COMPARISON
Collocated Data - Site 7
5 6 7 8 11 12 13 14 18
DAY
Location a -•— Location b I
TABLE 5-5 - CONCENTRATION READINGS FROM THE NAAQS PERMANENT
MONITORING SITE IN UNION CITY, NJ *
DATE
CONCENTRATION VALUE (in /ig/m')
July 5 41
1 July 11
25July 17 27
1 July 23
18FIGURE 5-4 - Comparison of PM,o concentration readings from
high volime szunplers to the LRAPA Seunplers (from study
performed in Research Triangle Park, NC).
Reference vs. LRAPA Sampler Comparison
30.0 28.0-
p26.0-
ͣ \24.0H 322.0- Q 20.0 I- a 18.0 S 16.0- o o 14.0- o 12.0H 10.0 3 DAYWedding "••" Andersen LRAPA #408 LRAPA #409