Bridgeton Landfill Data Review Update
Primarily reflects data and documents published on Missouri Department of Natural Resources'
webpage for data collected in February 2014
Introductory Remarks
The ORD Engineering Technical Support Center (ETSC)
and their subcontractor reviewed data and reports on the
Bridgeton Landfill available at the Missouri Department of
Natural Resources (MDNR) Bridgeton Landfill website.
The purpose of the review was to examine available
reported data collected at the landfill gas extraction wells
(GEWs), gas interceptor wells (GlWs), and temperature
monitoring probes (TMPs) as well as assess the presence
and movement of any subsurface oxidation event/heat
generating event occurring in the South Quarry, North
Quarry or the adjoining "neck" area {see figure on right).
The shaded areas shown in the figure are approximate and
are only intended to provide a quick reference to different
areas of interest.
The closure of the South Quarry and North Quarry landfill
cells was approved by MDNR in 2008 and 2010, respectively. The landfill cells were closed
with a 2-ft thick clay cap (with specified hydraulic conductivity <1 « 10"5 cm/sec) overlain by a
I-ft thick vegetative soil layer. To aid in landfill gas collection efficiency and help control odors,
an Ethylene Vinyl Alcohol (EVOH) flexible membrane liner cap was placed over 32 acres in the
South Quarry area (completed August 2013). An additional 10 acres of EVOH liner was placed
on other portions of the South Quarry and Neck Area (completed October 2013).
Installation of an approximately 21 acre EVOH cap for the North Quarry was approved in the
revised North Quarry Action Plan, dated November 2013. As of February 2014, 4.35 acres of
what we believe from reports to be the EVOH cap was installed on the North Quarry, as well as
the installation of 23 additional gas extraction wells (GEWs). No major construction occurred in
the North Quarry in February 2014.
North Quarry
Temperature
February 2014 temperature measurements in the GEWs showed mostly stable or slightly
decreasing levels compared to January 2014. All wells but one maintained a negative pressure
during the entirety of the month. Two of 24 wells had an applied vacuum greater than 2 inches
water column (" w.c.), GEW-07 and GEW-54. GEW-01 continued to exhibit high positive
pressures (17-24" w.c.). When a limited vacuum (<2" w.c.) is applied, the measured temperature
becomes a function of both the landfill gas and ambient air conditions, since a limited amount of
gas is being pulled through the well. The limited vacuum may be a function of the valve position
at the well or the available GEW system pressure.
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February 2014 GEW temperature data compared to January 2014 data indicate:
• Four GEWs exhibited increasing temperatures. Of these four, one well exhibited increasing
temperatures in the January report:
o GEW-01 (well also exhibited high positive pressure, this is not typical)
o GEW-07
o GEW-42R
o GEW-46R
• Eleven GEWs exhibited steady temperatures. Of these eleven, six wells exhibited steady
temperatures in the January report:
0
GEW-04
0
GEW-44
0
GEW-06
0
GEW-45R
0
GEW-08
0
GEW-4 8
0
GEW-40
0
GEW-50
0
GEW-41R
0
GEW-55
0
GEW-43R
• Nine GEWs exhibited decreasing temperatures. Of these nine, one well exhibited decreasing
temperatures in the January report:
0
GEW-02
0
GEW-51
0
GEW-03
0
GEW-52
0
GEW-05
0
GEW-53
0
GEW-47R
0
GEW-54
0
GEW-49
Collected Gas Quality
Strong trends from recently-collected data are difficult to assess because the applied vacuum at
several wells in the North Quarry were near 0" w.c. The limited applied vacuum (< 2" w.c.) at
these wells could be an administrative control to decrease the likelihood of exceeding a
temperature limit of 145 °F that has been imposed for the GEWs in the North Quarry.
Limiting the collected gas also limits the ability to detect subsurface heating conditions
based on data review alone. Therefore, we have low confidence in any of the stated
observations related to the gas quality data. That being said, gas quality in the North Quarry
GEWs generally shows CH4 and CO2 concentrations expected from anaerobic decomposition
conditions, though several wells had elevated balance gas concentrations as described below.
• Wells showing the highest balance gas concentrations were generally located in the
northern and central portion of the North quarry, and included the northern-most row
of GEWs (GEW-03, GEW-04, and GEW-05). High balance gas concentrations (not
indicative of normal decomposition) may warrant further examination.
• Fifteen out of 24 wells had balance gas concentrations >10%, with nine of these wells
exhibiting balance gas concentrations >30%. Balance gas is calculated by the landfill gas
monitoring device, and is defined as the percentage of gas that is not CH4, CO2, or O2. None
of the wells had elevated O2 concentrations. If the balance gas is comprised of gas other
than N2 or if atmospheric air is being pulled into the waste and consumed, the resultant gas
would have an elevated (>10%) balance gas and low O2 readings.
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• Laboratory analyses were not performed in February at the North Quarry GEWs.
Settlement
No settlement data were collected for the North Quarry by the landfill operators, therefore no
assessment was made in this document.
Neck Area
Temperature
Data from January 2014 through February 2014 demonstrate that several TMPs exhibited
increases in temperature at different depths. The following TMPs generally exhibited
temperature increases around 5 °F at several depths when compared to January 2014 data.
Temperatures in the remaining TMPs were generally stable,
o TMP-4 o TMP-11
o TMP-6 o TMP-12
o TMP-7R o TMP-14 (+8 °F)
o TMP-8
Additional observations from the TMP data include:
• TMP-7R: A 14 °F drop in temperature has been observed at 20 ft depth (feet = ') since
November 2013.
• TMP-8: A 10 °F drop in temperature was observed at 20'.
• TMP-12: Experiencing large temperature increases since October 2013. Now at highest
temperature recorded at this location (186 °F). TMP is located north of the northern-most
row of GIWs.
• TMP-14: +8 °F at 21'; +3 °F at 41'
Of the 13 GIWs monitored in the Neck Area in January 2014:
• Two exhibited temperature increases, GIW-11 and GIW-12 (these GIWs also showed
increases in January 2014)
• Eight GIWs exhibited highly variable temperature swings ranging from 20 to 90 °F. Two of
the eight wells (GIW-2 and GIW-3) exhibited an overall increasing temperature trend from
January 2014 to February 2014.
• Strong trends are difficult to assess in the GEWs located in the Neck Area because little
to no vacuum or a highly fluctuating vacuum is being applied at three of the six wells
(GEW-09, GEW-39, and GEW-110).
o GEW-09 exhibited increasing gas temperatures in the range of +8 °F, with a limited
applied vacuum (<2" w.c.).
o GEW-10, the northern-most GEW in the neck, has had limited applied vacuum since
July 2013 (and the valve appeared to be closed in January 2014 as exhibited by
positive pressures). The variable temperatures exhibited at this well continued
throughout February 2014, although the vacuum was operated at an average of 9"
w.c.
o GEW-56R, located just to the north of the northern-most row of TMPs, exhibited
relatively steady temperatures from January 2014 throughout February 2014. The
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well was operated with substantial vacuum (9 to 19" w.c.) for the majority of the
month, before being turned down in the latter part of February (1 to 3" w.c.) and
maintaining stable temperatures,
o GEW-109 also consistently maintained vacuum >2" w.c. in February, but the vacuum
has decreased throughout the month; temperatures have increased throughout the
month of February, and in comparison with January 2014 data (January high of 162
°F, February high of 167 °F after initially decreasing with higher vacuum applied in
the beginning of the month),
o GEW-39 and GEW-110, have exhibited increasing temperatures throughout February
in comparison to January data (3 to 5 °F and 12 °F respectively); this correlates with
little to no vacuum pressure being applied to the well.
Collected Gas Quality
Gas quality collected in the Neck Area generally show CH4 and CO2 concentrations that
are not indicative of anaerobic decomposition conditions, with low or decreasing levels of
CH4 and elevated CO2 concentrations. These gas concentrations could be a reflection of
actual waste conditions near the well, or off-gassing from the reaction occurring in the South
Quarry.
• Four of six GEWs in the Neck Area exhibited elevated concentrations of balance gas ranging
from 10 to 70%, which is not indicative of typical anaerobic decomposition conditions.
• Hydrogen (Fh) concentrations greater than or equal to 10% were observed at two GEWs
[GEW-56R (10%>) and GEW-109 (31%)]. These wells also exhibited elevated Fh
concentrations in January 2014.
• There were no laboratory data available for GEW-09 in February 2014.
Settlement
The Neck Area was not included in the survey for February 2014.
South Quarry
February 2014 data were available for 40 GEWs in the South Quarry.
• 31 of the GEWs (—78%) had one or two individual readings, defined as a reading on a given
day (i.e., days with multiple readings at one well were not considered).
o Nine GEWs had data for one day in February (including multiple readings in one day)
o 22 GEWs had data for two days in February. This also includes multiple readings in
one day; some wells may have four data points corresponding to only two days of
readings.
Temperature
• A majority (24) GEWs had temperatures ranging from 140 °F to 200 °F.
• Two wells exhibited extreme temperature increases in February. GEW-100 showed a
+100 °F jump (from 30 °F to 130 °F) and GEW-34 showed a +62 °F jump (from 131 °F to
193 °F); both wells exhibited elevated positive pressures at the time of the increased
temperature measurement. The increase at GEW-100 coincided with the application of
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vacuum during the time of measurement - previous readings have showed erratic measured
pressures, including many positive or near-zero vacuum measurements since November
2013.
• 10 of the GEWs exhibited sustained temperatures <100 °F. Three of these GEWs had low or
positive applied vacuums in February (GEW-24A, GEW-37 and GEW-116).
Collected Gas Quality
In February 2014, none of the GEWs in the South Quarry exhibited gas concentrations
consistent with predominantly anaerobic waste decomposition conditions.
• Three GEWs in the South Quarry appeared to be closed, based on vacuum pressure data.
o GEW-34
o GEW-77
o GEW-80
• Low CH4 readings (<20%) were observed for all wells, with the majority of wells having
CH4 levels below 5% (32 GEWs).
• The majority of reported CO2 concentrations were within the 60-90% range.
o Seven wells exhibited CO2 concentrations below 30%, along with low CH4
concentrations.
• Balance gas was generally 20-40%, and in several GEWs 50-10% balance gas was observed
during the month of February. O2 levels were generally at or near 0%; however, nine wells
exhibited O2 levels >10% , suggesting atmospheric air intrusion; five of these wells had O2
levels >10%) in January 2014:
0
GEW-20A
0 GEW-79R
0
GEW-34 A
0 GEW-85
0
GEW-35
0 GEW-101
0
GEW-36
0 GEW-103
0
GEW-37
Settlement
The areas with the greatest change in elevation continue to be located in the southern-central
portion of the South Quarry. The majority of the South Quarry continues to show a monthly
elevation drop of approximately 2 ft. No appreciable changes in settlement were observed in the
area immediately south of the neck.
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