Bridgeton Landfill Data Review Update
Primarily Reflects Data and Documents Published on MDNR's Webpage for data collected
between January and March 2015
Introductory Remarks
The ORD Engineering Technical Support Center (ETSC)
and their subcontractor reviewed data and reports 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
(GIWs), and temperature monitoring probes (TMPs) to
assess the presence and progression of any subsurface
oxidation event/heat-generating event occurring in the
South Quarry, North Quarry or the adjoining "Neck" area
(see figure on right for an approximate depiction of these
areas and the adjacent West/ake Landfill OZJ-1 cell). The
shaded areas shown in the figure are intended to provide a
quick reference to different areas of interest. This report
analyzes data primarily collected during January,
February, and March 2015.
The South Quarry and North Quarry landfill cells began the closure process in 2008 and 2010,
respectively. The landfill cells were covered with a 2-ft thick clay cap (with specified hydraulic
conductivity <1 * 10"5 cm/sec) overlain by a 1 -ft thick vegetative soil layer. An ethylene vinyl
alcohol (EVOH) flexible membrane cap was placed over the South Quarry, Neck Area, and a
portion of the North Quarry in 2013 and 2014. Work was initiated in the South Quarry at
various times in 2014 and 2015 to repair slopes that had subsided
This document provides a summary and discussion of data collected in North Quarry, Neck
Area, and South Quarry of the landfill. Observations on the flare data are also provided below:
• The flow rate of CH4 (range of 590-672 standard cubic feet per minute (scfm)) and CO2
(1,964-2,396 scfm) from the flare was less than that measured with the GEM in
December 2014. The balance gas flow rate had a range of 3,160-3,670 scfm from
January-March 2015 and was less than in December 2014 (3,688 scfm).
• The average total flare flow rate had a range of 6,916-7,068 scfm from January-March
2015 was less than the average total flare flow rate in December 2014 (7,771 scfm).
Flare data are subject to further examination, as subsequent meetings in December 2015 and
January 2016 indicate the flow measurements for the overall gas collection system and flares
were not accurate, and flow data for the mentioned systems were not accurately measured until
after March 12, 2015 (per MDNR). Flowever, it is our understanding that flow data from
individual GEWs and GIWs were accurate throughout 2015.
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North Quarry
Temperature
January 2015 to March 2015 temperature measurements in the GEWs showed mostly
steady levels. One out of 23 GEWs (GEW-45R) maintained a negative pressure during all three
months with pressures less than 2 inches water column (" w.c.), with one measurement
exhibiting a vacuum greater than 2" w.c. The remaining wells had a limited vacuum or no
vacuum (0" w.c.). The limited vacuum may be a function of the valve position at the well or the
available GEW system pressure. GEWs in the North Quarry generally showed steady
temperatures. In limited instances (e.g., GEW-42R and GEW-45R in January), wells showed a
substantial change (increase or decrease) but measured temperature indicated strong ambient
influence. In February and March, GEW-54 had a measured temperature greater than 145 °F
(148 and 146 °F, respectively).
Temperature data for the three new TMPs in the North Quarry were available starting August
2014 (TMPs 16, 17 and 18). The TMP data from December 2014 through March 2015 showed
temperatures in the North Quarry had a stable or slightly increasing trend with most increases
being less than 2 °F. TMP temperature observations of increases greater than +2 °F are
presented:
• TMP-16 (+2.5 °F at 153-ft depth)
• TMP-17 (+2.7 °F at 100-ft depth)
Collected Gas Quality
Overall, the GEWs exhibited expected CH4 and CO2 concentrations from anaerobic
conditions within the landfill, though there were a few wells that displayed elevated balance
gas concentrations, which are discussed below. As in previous months, many of the wells
had low or no applied vacuum, which confounds discerning trends.
• In January 2015, nine out of 23 wells exhibited balance gas concentrations >10%, with
six wells (GEW-03, GEW-05, GEW-44, GEW-46R, GEW-47R, and GEW-49) having
balance gas concentrations >20%. Laboratory analyses were conducted for gasses
collected from 22 of the 23 wells. H2 and N2 concentrations were >10% for five of the
wells, which correlates well with the field-measured balance gas concentrations. GEW-53
was the only well that had a detected CO concentration (41 ppm), while the remaining 21
wells had measurements less than the detection limit.
• In February 2015, five of the 23 wells exhibited balance gas concentrations > 10%, with
one well (GEW-49) having concentrations >20%. Only six of the 23 wells were sampled
for laboratory analysis. The N2 and H2 results detected remained below 10% in
concentration and were broadly consistent with field measurements. Of the six wells
analyzed in the laboratory, only one well (GEW-08) had a CO concentration greater than
the laboratory detection limit (30 ppm), while the remaining five wells did not detect any
CO.
• In March 2015, four of the 20 wells sampled had balance gas concentrations > 10%,
with two wells (GEW-44 and GEW-49) having concentrations >20%. Twenty of the 23
wells were sampled for laboratory analysis. Three of the samples exhibited N2
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concentrations greater than 10%. GEW-08, GEW-53, and GEW-55 were the only wells
with detected CO concentrations of 33, 52, and 34 ppm, respectively. The remaining
sampled wells had CO concentrations less than the laboratory detection limit.
Settlement
No settlement data were collected for the North Quarry from January to March 2015.
Neck Area
Temperature
Data demonstrated several TMPs exhibited increases in temperature over a range of depths. The
following TMPs generally had multiple depths with measured temperatures that were steady, but
had some depths with temperature increases (these instances were typically < 2 °F; depths with
greater increases are noted) when compared to December 2014 data,
o TMP-4R (+2.5 °F at 20-ft depth, +2.8 °F at 29-ft depth)
o TMP-6 (+4.2 °F at 15-ft depth)
o TMP-11 (+5.6 °F at 16-ft depth, +3.5 °F at 3 6-ft depth)
o TMP-14 (+2.3 °F at 41-ft depth, +5 °F at 61-ft depth, +3.1°F at 81-ft depth, +7.7°F
at 101 -ft depth, +13.2 °F at 161 -ft depth,+2.4 °F at 201 -ft depth)
TMP-14 exhibited consistently increasing temperatures at five depths (41,61,81, 101, and 161
ft) over the January-March time period. Similar trends were also observed in TMP-11 at two
depths (16 ft and 36 ft).
Temperatures in the remaining TMPs were generally stable; however, overall temperature trends
are difficult to assess. This is due to failure of either individual thermocouples at specific depths
on a TMP, or failure of an entire TMP thermocouple cluster (no readings at any depth) for 10 of
the original 14 TMP clusters. For example, there have been no readings for TMPs 7R or 13
since April 2014 and March 2014, respectively. It has been recognized that many of the depth
intervals of several TMPs have been compromised because of the shifting waste mass,
settlement, or the presence of gas and/or liquid in the TMP well.
Temperature trends in GIWs were generally stead from January to March. Two of the 13
GIWs (GIW-01 and GIW-08) maintained constant vacuums through the entire three-month
period, with GIW-01 measurements having pressures consistently > 2" w.c. The remaining wells
either had a limited vacuum (< 2" w.c.) or no vacuum applied (~ 0" w.c.).
Most GEWs exhibited steady trends in temperatures throughout the three-month period, with
some minor exceptions. Wells with varying trends and other important observations are detailed
as follows:
• GEW-10 is the only well to maintain a temperature less than below 100 °F for the entire
three-month period.
• GEW-109 showed an increasing trend in temperature, especially in January and March,
with temperature measurements > 145 °F. The well generally held a strong vacuum
throughout the entire three-month period, with pressures > 2" w.c.
• Three wells (GEW-09, GEW-39, and GEW-56R) displayed steady temperatures
throughout the entire three-month period. All three wells had temperatures >100 °F, with
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GEW-39 having temperatures < 145 °F and GEW-56R having recorded temperatures >
145 °F.
Collected Gas Quality
Four out of the six GEWs (GEW-39, GEW-56R, GEW-109, GEW-110) in the Neck area
exhibited elevated concentrations of both balance gas and CO2 resulting in decreased levels
of methane, indicating non-anaerobic conditions. The CO2 concentrations ranged from 14.7 -
66.6%, while balance gas ranged from 7-69.2%. GEW-110 also displayed measurements of high
levels of oxygen (>10%) during all three months.
All 13 GIWs exhibited high concentrations of balance gas and CO2, resulting in decreased
methane concentrations. Balance gas concentrations were elevated for the three-month duration
with the majority having values > 20%. CH4 concentrations remained < 30% for 12 of the GIWs
for the entire three-month period, with 11 wells consistently displaying concentrations < 10%.
Elevated O2 levels, with concentrations > 10% occurred at certain wells every month. In January,
two wells (GIW-08 and GIW-10) had concentrations of 13.2% and 11.2%. In February, three
wells (GIW-02, GIW-05, and GIW-12) had concentrations of 10.2, 10.6 and 10.9%, respectively.
In March, GIW-03, GIW-04, GIW-08, and GIW-12 had concentrations of 20.2%, 14%, 17.2%,
and 12.3% respectively.
Settlement
Monthly settlement rates in the Neck Area mostly ranged between 0 to 1 feet from January to
March 2015. Increases in elevation mostly occurred in northeast and northwest areas of the neck
as shown in the Monthly Bridgeton Landfill Reports, with a maximum increase of 0.15 feet.
Settlement data in the neck are limited and do not encompass the entire Neck Area.
South Quarry
Temperature
• Three GEWs had temperatures greater than or equal to 200 °F (GEW-71 (200 °F),
GEW-90 (203 °F); and GEW-147 (202 °F)).
• 51 GEWs had temperatures ranging from 140 °F to 200 °F between January and
March 2015 (there were 37 GEWs in this range between October and December 2014).
• 24 of the GEWs exhibited constant temperatures <100 °F during the three-month period. All
but three of these wells (GEW-33R, GEW-84, and GEW-117) generally maintained a
vacuum of consistently greater than 2" w.c. (There were 22 GEWs in this range between
October and December 2014).
• Nine GEWs in the South Quarry appeared to be closed during the three-month period based
on vacuum pressure data (see below). Of these, GEW-22R and GEW-137 only appeared to
be closed during March. Fourteen wells appeared closed between August and September
2014.
GEW-22R
GEW-71
GEW-137
GEW-25A
GEW-84
GEW-138
GEW-33R
GEW-117
GEW-148
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Collected Gas Quality
Between January and March 2015, as in October-December 2014, one of the GEWs (GEW-
117) in the South Quarry exhibited gas concentrations consistent with predominantly
anaerobic waste decomposition conditions.
• Consistently low CH4 readings (< 30%) were observed for almost all wells (all but one well,
GEW-117), the number of wells showing CH4 levels < 5% during the three-month period
has increased since December 2014 (71 wells as compared to 62 between October and
December 2014).
• 34 wells exhibited C02 concentrations < 30%, and low CH4 concentrations. The remaining
reported CO2 concentrations were within the 50% to 80% range.
• Balance gas was generally 20% to 50%, and in several GEWs balance gas was > 50%,
measuring up to 80% between January and March 2015.
• O2 levels were generally < 5%; however, 34 wells exhibited O2 levels > 10% between
January and March 2015 (see below), suggesting atmospheric air intrusion; 24 wells had O2
levels > 10%) between October and December 2014:
GEW-014A
GEW-070R
GEW-125
GEW-145
GEW-018R
GEW-083
GEW-127
GEW-146
GEW-020A
GEW-086
GEW-133
GEW-148
GEW-021A
GEW-089
GEW-134
GEW-149
GEW-027A
GEW-101
GEW-135
GEW-151
GEW-037
GEW-103
GEW-136
GEW-153
GEW-038
GEW-116
GEW-137
GEW-154
GEW-061B
GEW-120
GEW-141
GEW-069R
GEW-124
GEW-144
Settlement
Between January and March 2015, the areas with the greatest change in elevation were located in
the southern-central portion of the South Quarry, with a monthly settlement of approximately
1.75 ft. These rates were a bit less than the monthly settlement rates during October to December
2014, which ranged from 2 to 2.4 ft per month. The majority of the South Quarry continues to
show a monthly drop of approximately 0 to 1 ft. The rate of settlement directly south of the neck
continues to be small and stable compared to late 2014 levels. No appreciable changes in
settlement rates were observed in the area immediately south of the neck area.
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