Corrective Action Measures Inert Gas Injection (IGI) Work ...inert gas injection as a secondary...

Correc t ive Ac t ion Measures Iner t Gas In jec t ion Work P lan

for Hot Spot Remediation

Presented to:

B r i d g e t o n L a n d f i l l , L L C 13570 St. Charles Rock Road

Bridgeton, Missouri 63044 (314) 744-8166

Presented by:

S C S E N G I N E E R S 2060 Reading Road, Suite 200

Cincinnati, Ohio 45202 (513) 421-5353

April 25, 2018

File No. 23211003.04

Offices Nationwide www.scsengineers.com

B r i d g e t o n L a n d f i l l , L L C

C o r r e c t i v e A c t i o n M e a s u r e s I n e r t G a s I n j e c t i o n W o r k P l a n

f o r H o t S p o t R e m e d i a t i o n

Presented To:

B r i d g e t o n L a n d f i l l , L L C 13570 St. Charles Rock Road

Bridgeton, Missouri 63044 (314) 744-8166

Presented From:

S C S E N G I N E E R S 2060 Reading Road, Suite 200

Cincinnati, Ohio 45202 (513) 421-5353

April 25, 2018

File No. 23211003.04


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T a b l e o f C o n t e n t s Section Page 1.0 Introduction ............................................................................................................................................. 1 2.0 Inert Gas Injection Background ........................................................................................................... 1 3.0 Response To Trigger Value Exceedances ......................................................................................... 3 4.0 Response To Trigger Values At Depths Less Than 40 Feet ............................................................ 5

4.1 Corrective Actions To Be Completed Within Seven Days .................................................... 6 4.2 Corrective Actions Completed After Seven Days .................................................................. 7

4.2.1 Identification of Affected Area ........................................................................... 7 4.2.1.1 Surface Observations .................................................................................... 7 4.2.1.2 Subsurface Investigation ................................................................................ 7

4.2.2 Additional Gas Injection Point Array Installation ............................................. 9 4.2.3 Injection of Inert Gas .......................................................................................... 9 4.2.4 Monitoring .......................................................................................................... 10

4.2.4.1 Injection Monitoring ...................................................................................... 10 4.2.4.2 Performance Monitoring .............................................................................. 11

5.0 Response To Trigger Values At Depths Greater Than 40 Feet................................................... 11 5.1 Corrective Actions To Be Completed Within Seven Days ................................................. 11 5.2 Corrective Actions Completed After Seven Days ............................................................... 12

5.2.1 Injection of Inert G a s ........................................................................................ 13 5.2.2 Injection Monitoring ............................................................................................ 13 5.2.3 Post Injection Monitoring .................................................................................... 14 5.2.4 Cooling Loop Activation .................................................................................... 14 5.2.5 TMP Array Monitoring........................................................................................ 14

5.3 Performance Evaluation ........................................................................................................... 14 6.0 Schedule ................................................................................................................................................ 15

6.1 Corrective Actions Completed After Seven Days For Triggers At Depths Less Than 40 Feet 15 6.2 Corrective Actions Completed After Seven Days For Triggers At Depths Greater Than 40 Feet .................................................................................................................................................. 16

7.0 Materials, Contractors, And Vendors ............................................................................................... 16 8.0 Reporting ............................................................................................................................................... 18

L i s t o f F i g u r e s

No. 1 Bridgeton Landfill Remedial Team Organization Chart 2 Trigger Exceedance and Action Decision Tree 3 Schedule For Actions To Be Completed After 7 Days For A Trigger At A Depth Of Less

Than 40 Feet 4 Gas Injection Point Perforation Detail 5 Combined Cooling/Injection Well Conceptual Design 6 Schedule For Actions To Be Completed After 7 Days For a Trigger Depth Greater Than 40

Feet


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A p p e n d i c e s Appendix A Bridgeton Landfill SOP, Section 17, Subsurface Oxidation Events


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1 .0 INTRODUCT ION

In the US EPA Administrative Settlement Agreement and Order on Consent for Removal Actions (the AOC) dated April 28, 2016, the US EPA required that Bridgeton Landfill, LLC (Bridgeton) prepare and submit:

“…a Work Plan with schedule for use of Inert Gas Injection as a “hot spot” treatment option to isolate, contain, suppress, inhibit and/or extinguish an independent surface/subsurface smoldering event/fire that may occur in the “Neck” area or in the North Quarry of the Bridgeton Landfill. “

For the purposes of this work plan, an “independent surface/subsurface smoldering event/fire occurring in North Quarry of the Bridgeton Landfill” (event) is defined as/by the occurrence of an exceedance of one of the following trigger values:

A landfill gas temperature above 185 oF in a landfill gas extraction well. A carbon monoxide (CO) concentration above 1,500 ppm detected in the landfill gas in

a landfill gas extraction well. A subsurface, in situ waste temperature above 200 oF as measured by one of the

thermocouples within a temperature monitoring probe. Based SCS’s experience in the industry and at Bridgeton specifically, there are two processes that could result in an event. One process is a subsurface landfill fire, which typically results from overdrawing a landfill gas extraction well, which creates a short circuit between the atmosphere above the surface of the cap and the top of the screened section of the well. The introduction of air into the waste mass can result in the ignition and combustion of combustible material in the waste. The other process that could result in an event is an accelerated exothermic chemical reaction or reactions that are occurring under anaerobic conditions in saturated waste at depths greater than a shallow subsurface landfill fire. The response to events at different depth ranges needs to be tailored the depth at which the process that results in an event is occurring. Below, this report presents the response to the trigger values included in the AOC and the procedures to determine which corrective actions are implemented and the schedule for their implementation. Bridgeton has identified a team of employees, consultants, and contractors who will be responsible for implementing the plan described below. An organization chart for the team is presented in Figure 1.

2.0 INERT GAS INJECTION BACKGROUND

Historically, inert gas injection has been implemented as a secondary strategy to attempt to extinguish subsurface landfill fires. (The term “extinguish” is used in this context to mean stopping an oxygen-supported combustion event or fire.) Subsurface landfill fires typically result from overdrawing landfill gas extraction wells, which creates a short circuit between the atmosphere above the surface of the cap and the top of the screened section of the well. Other less frequent causes of subsurface landfill fires include the creation of a similar short circuit due


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to a failure of a subsurface header line under system vacuum or the injection of air into the subsurface due to a failure of a subsurface compressed air line. The introduction of air into the waste mass can result in the spontaneous combustion of organic material in the waste. The typical design of landfill gas extraction wells rarely has the top of the screen set at depths greater than 40 feet below the landfill surface. This typically limits the short circuit pathway and the potentially resulting subsurface landfill fire event to depths less than 40 feet. Standard industry practice to address subsurface landfill fires is to “smother and cover,” with inert gas injection being the next most popular remedial approach. With smother and cover, points of air intrusion are identified and sealed off, and the surface cover is enhanced. More specifically, the cause of the short circuit is identified and controlled. As part of this process, the vacuum applied to the landfill gas extraction well in question is temporarily shut off and entry points for air through the cap are identified and sealed with additional recompacted soil. Once the fire is deprived of oxygen, it generally goes out. The impacted area is typically observed for a number of weeks to verify the fire is out before the operation of landfill gas wells in the vicinity are restarted. If the fire persists, typical industry practice is to perform inert gas injection as a secondary attempt to extinguish the fire. The injection of inert gas both cools the waste and displaces the oxygen needed for combustion. The impact of the inert gas depends on the gas moving through interconnected pore space in the refuse. The deeper into waste, the more dense and compact the waste becomes due to the weight of overlying waste, and therefore the smaller and less interconnected the pore spaces become. When inert gas injection is not successful in extinguishing a fire, it is typically because a volume of burning waste is isolated from the inert gas. Once the inert gas disperses and oxygen reaches the isolated volume of waste, the fire can reignite. The effective depth of inert gas injection is considered to be 40 feet. Fortunately, this is likely the maximum depth at which a short circuit to the atmosphere will occur due to the reduction of interconnected pore space in the refuse. Carbon dioxide and nitrogen have been used to combat typical subsurface landfill fires. When these gases are introduced into the subsurface under pressure, they cool the fuel and displace the oxygen that is supporting combustion. Inert gases can be injected in a gaseous or liquid state. Injection of the inert gas initially in a liquid state allows the material to transform to gas in the subsurface, providing additional cooling and driving force beyond the injection pressure as the liquid “boils” and the gas expands. Liquid carbon dioxide (CO2) is the preferred inert gas for subsurface injection. Liquid CO2 is easier to work with than liquid nitrogen (N2) because of the extreme temperatures of liquid nitrogen, which boils at -321 °F. Liquid CO2 boils at -106 °F. The less extreme temperatures and pressures of liquid CO2 compared to liquid nitrogen represent a lower safety risk. A gram-mole of liquid CO2 at 25 degrees Celsius (°C) and 300 pounds per square inch (psi) will expand to 22.4 liters at standard temperature and pressure (STP) conditions (0 °C and 1 atmosphere). This is equivalent to about 8.2 cubic feet (ft3) per pound or 16,433 ft3 per ton of liquid CO2.

The injection of inert gas has been successful in extinguishing some subsurface landfill fire events. The challenge for the injection of inert gas is ensuring that it is introduced into the landfill in such a manner so that it is uniformly distributed throughout the impacted materials.


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Municipal solid waste in a landfill is a heterogeneous material. Depending on the specific items and materials that make up the waste and the variability of the compaction effort, some denser areas may remain isolated from the gas. In these instances, the subsurface landfill fire event may rebound and, in the worst case scenario, continue to expand. In these cases, a repeat of the inert gas injection program or the application of other control measures would be required to remediate the subsurface landfill fire event. The injection of inert gas may have a negative impact on the gas collection and control system (GCCS). Typically, the landfill gas collection system is turned off in the immediate vicinity of the injection activity. The landfill gas collection system can be turned off in a wider area extending beyond the impacted area during treatment if necessary. For example if the subsurface landfill fire event area remains under vacuum, additional wells will need to be turned off. If part of the landfill gas collection system remains active, gas extraction wells near the injection area might be used to “steer” the migration of the treatment gas. The downside of leaving the landfill gas collection system active near the treatment area would be the capture of a significant amount of the injected treatment gas, which would reduce the heat value of the collected landfill gas. If the methane (and/or hydrogen and CO) content is sufficiently reduced, the flare(s) could require supplemental fuel to burn. Bridgeton Landfill has a natural gas line connected to the flares that will be used if needed to supplement the landfill gas and keep the flares operating if inert gas is drawn into the collection and control system. As noted above, given the density of the waste at depth and its saturated condition at Bridgeton Landfill, the injected inert gas will not travel substantially beyond the injection point.

3.0 RESPONSE TO TRIGGER VALUE EXCEEDANCES

The AOC incorporates the following trigger values for the implementation of inert gas injection:

“…greater than 185o F or 1500 ppm of carbon monoxide in a gas extraction well or greater than 200o F in a temperature monitoring probe.”

The response to a confirmed trigger value exceedance is illustrated in the decision tree presented as Figure 2. The decision tree offers two different response pathways, with the path determined based on the depth of the exceedance. Bridgeton will notify the US EPA and the MDNR within 24 hours of the measurement of the initial temperature exceedance or receipt of laboratory results showing a CO exceedance. Following the reading of a measurement that exceeds the temperature trigger value in a temperature monitoring probe or landfill gas extraction well or receipt of a laboratory report showing a CO concentration that exceeds the trigger value in a landfill gas extraction well:

Bridgeton will collect an additional temperature reading at the monitoring point exhibiting the initial exceedance or collect a gas sample for laboratory analysis to confirm the CO exceedance within 24 hours of measurement or the CO concentration within 2 business days of receipt of the sample by the laboratory.

Bridgeton will perform a comparison of the trigger value and the confirmation reading based on data and trends prior to the exceedance.


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If the initial temperature measurement is suspected to be anomalous based on previous data and trends, two additional readings will be taken within 24 hours to confirm the initial reading.

If either of the two follow-up readings exceeds the trigger, the initial measurement will be deemed verified unless the US EPA and the MDNR are in agreement with Bridgeton to the contrary.

If the initial CO result is suspected to be anomalous based on previous data and trends, two additional samples will be collected and analyzed at the monitoring point exhibiting the CO exceedance.

The first confirmation sample will be collected within 24 hours of receipt of the laboratory results for the initial sample and the analysis will be performed within 2 business days of the receipt of the sample by the laboratory.

The second sample will be collected within 24 hours of the receipt of the results of the first confirmation sample and the analysis will be performed within 2 business days of the receipt of the sample by the laboratory.

Bridgeton Landfill will notify the US EPA and the MDNR within 24 hours of the measurement of a confirmed trigger value exceedance.

Bridgeton will also contact the drilling subcontractors needed to respond to the specific trigger value recorded. As described further below, a direct push type drilling rig is required to address a trigger value at a depth less than 40 feet. As described further below, a bucket auger drilling rig and/or a sonic type drilling rig are required to address a trigger value at a depth greater than 40 feet.

Bridgeton will contact appropriate drilling subcontractors needed to respond within seven days of the initial trigger exceedance.

The following corrective actions will be completed within 24 hours of a confirmed trigger value exceedance:

If the trigger value exceedance has been measured in an operating landfill gas extraction well, shut down the subject landfill gas extraction well (i.e., stop applying vacuum and withdrawing gas from the well).

Measure the vertical temperature profile in all the active landfill gas extraction wells within 300 feet of the affected landfill gas extraction well or temperature monitoring probe (TMP). Shut down any active landfill gas extraction wells in the vicinity (within a radius of approximately 300 feet) of the affected landfill gas extraction well or TMP that exhibit a temperature exceedance. Bridgeton will report the results of the vertical temperature readings to US EPA and MDNR within 24 hours of a confirmed trigger exceedance.


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For trigger value exceedances at depths less than 40 feet, initial inert gas injection will be implemented within seven calendar days. The 40 foot depth was selected based on industry experience with the direct push drilling method’s ability to reliably install gas injection points to this depth. With additional depth, the likelihood that the direct push probe will experience refusal before reaching the target depth increases significantly. Refusal can result from either encountering materials that the probe cannot drive through, including concrete, metal, tires, etc., or from the friction from dense material exceeding the driving force of the rig. The combination of the general availability of the direct push rigs, and their ability to rapidly mobilize and install an injection point, combine to allow inert gas injection to be accomplished within seven days.

Simultaneous with the process of implementing the initial inert gas injection, an evaluation of the location and the extent of the conditions resulting in the trigger exceedance will begin. If symptoms are observed at the landfill surface, the implementation of other remedial actions not required by the AOC but required by internal Bridgeton Standard Operating Procedures (SOPs) will also begin. The response to trigger values at depths less than 40 feet is described in detail in Section 4.0 below. The second pathway on the decision tree is for trigger value exceedances that occur at depths greater than 40 feet. The response to trigger value exceedances at depths greater than 40 feet will require a different type of drilling rig, either a bucket auger rig or a sonic rig. These types of rigs are less generally available and the additional time required for the drilling and installation of any downhole apparatus, relative to the time required to install shallow injection points with a direct push rig, means that it is not feasible to commit to performing inert gas injection at depth within seven days. If the trigger value is measured in an existing landfill gas extraction well, a cooling loop will be installed in the wells and operation of the cooling loop will begin within seven days of the trigger exceedance. In addition, an array of TMPs and combination cooling installations will be installed around the impacted TMP/well. The response to trigger values at depths greater than 40 feet is described in detail in Section 5.0 below. It the affected area extends from less than 40 feet to deeper than 40 feet, both pathways will be implemented simultaneously.

4.0 RESPONSE TO TRIGGER VALUES AT DEPTHS LESS THAN 40 FEET

This section describes the response to trigger value exceedances that occur at depths less than 40 feet, including those actions that will take place within seven days and those actions that will begin within seven days but will continue and be completed after seven days.


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4 . 1 CORRECTIVE ACTIONS TO BE COMPLETED WITHIN SEVEN DAYS

The following corrective actions will be completed within seven days of a trigger value exceedance at a depth less than 40 feet:

Mobilize a direct push drill rig.

Contact vendors for materials and supplies needed above and beyond the materials stockpiled per the AOC.

Notify the CO2 vendor of the impending mobilization to the site.

Construct any access roads needed to allow the drilling rig, support vehicles, and liquid CO2 delivery vehicles to reach the injection area.

Install an initial inert gas injection point (GIP) to a depth of 35 to 40 feet. The selection of the location of the GIP is described below. The construction of the GIP is described in Section 4.2.2.

Mobilize the CO2 supplier to the site.

Inject liquid CO2 into the GIP. The injection and monitoring processes are described in Section 4.2.3.

The location of the GIP will be determined from the location of surface symptoms, further described in Appendix A, if present. The GIP will be located at the edge of the surface symptom area closed to the gas extraction well or TMP where the trigger value exceedance was recorded. If no surface symptoms are present, the GIP will be located based on temperature and/or CO readings in the gas extraction wells and/or TMPs in the vicinity of the triggered well or TMP. The GIP will be located approximately 50 feet from the impacted well/TMP, in line with the nearby well/TMP with the highest temperature or CO concentration relative to the specific trigger. Variation from these proposed locations will be discussed with US EPA if required by field conditions or other issues that make these proposed locations infeasible. If surface symptoms are observed, Bridgeton will immediately begin to implement its SOPs to remediate a subsurface landfill fire event as described in Appendix A, Bridgeton Landfill SOP, Subsurface Oxidation Events. This document is an internal Bridgeton Landfill document. Some of the bullet items above are included in the SOP. Actions included in the SOP but not listed above that will also be implemented within seven days include:

Cap and/or repair any item identified as contributing to air intrusion into the subsurface of the landfill.

Add additional cover to areas where observed cap integrity issues may be contributing to air intrusion in to the subsurface of the landfill.


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4 . 2 C O R R E C T I V E A C T I O N S C O M P L E T E D A F T E R S E V E N D A Y S

The following actions will begin within the seven days following the trigger value exceedance, but will not be completed within those first seven days. 4 . 2 . 1 I d e n t i f i c a t i o n o f A f f e c t e d A r e a

The most likely cause of a trigger value exceedance at a depth less than 40 feet is a subsurface landfill fire event. The affected area must be delineated in order to design an effective injection plan. 4.2.1.1 Surface Observations

Surface observations to be performed to identify the presence and extent of the affected area include, but may not be limited to:

Dramatic localized landfill settlement. Charred or cracked surface cover. Stressed or dead vegetation in an area that is otherwise properly vegetated. Smoke or smoky odor emanating from the landfill surface or well head. Drastic or unusual increase in flowing gas temperature. Abnormal discoloration of well head/riser assembly. High carbon monoxide (CO) concentrations (>1,000 ppm) in landfill gas (LFG). Deformed riser pipes.

These symptoms will be used, not only to identify the presence of a subsurface landfill fire event, but to also evaluate its areal extent. A hand-held infrared (IR) laser thermometer or equivalent device will also be utilized to perform a ground-based IR thermometer survey. Extreme caution must be taken in these areas due to the possibility of the ground giving way. The area will be marked with caution tape to prevent individuals from walking or driving in the area of concern. 4.2.1.2 Subsurface Investigation

In order to design the injection point array to maximize the effect of the inert gas, the vertical extent of the subsurface landfill fire event should be defined. Given that the injection gas will tend to flow towards the lower atmospheric pressure at the ground surface, the injection points should be located at or just below the base of the subsurface landfill fire event area. One or more of the following methods will be used to evaluate the vertical extent of the subsurface landfill fire event. 4.2.1.2.1 Downhole temperature monitoring

If one or more gas extraction wells are present in the subsurface landfill fire event area, downhole temperature measurements will be made in these wells.


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It should be noted that the procedures below may expose the observer to certain risks, including but not limited to:

Explosive concentrations of some combination of methane, hydrogen, and/or carbon monoxide.

High concentrations of volatile organic compounds (VOCs). High temperature gas and liquids. High temperature well components.

Personnel performing the investigation shall adhere to the Health and Safety Plan, North Quarry and Neck Area Removal Actions, Bridgeton Landfill, LLC-West Lake Landfill Superfund Site (Feezor, 2016). In order to prevent the introduction of large quantities of air into the collection system, the vacuum to each well for which downhole temperature monitoring is being performed will be shut off or reduced significantly prior to performing the monitoring activities. Depending on the well head construction, an access port will be opened or the well head will be removed. Next, an electronic water level indicator or equivalent measuring device will be lowered down the well to determine the depth to liquid. Then, a thermocouple will be lowered into the well to record the temperature at 5-foot intervals below the surface. Subsurface landfill fire events are typically shallow; therefore, the measurements would not be performed below the liquid level in the well, if present. 4.2.1.2.2 Thermocouple Array Installation

The extent of the subsurface landfill fire event would be assessed using in situ subsurface temperature measurements by installing arrays of thermocouples at regular depth intervals below the surface. The thermocouple arrays cannot be installed within the actual area of combustion, but would be installed outside the area of combustion to evaluate the vertical distribution of heat from the subsurface landfill fire event. The arrays will be installed using Direct Push Technology (DPT) drilling methods. The DPT drill pipe will be advanced to the target depth with a disposable point. The arrays will consist of thermocouples attached to a solid spine of plastic or fiberglass rod. The thermocouples will be attached to the spine at 5-foot intervals with electrical tape. The wires will be secured to the spine above each of the thermocouples. The wire leads will be clearly labeled to identify the depth of burial of each of the thermocouples. The spine and thermocouple array will be placed in the drill rod. The drill rod will be withdrawn and the annulus between the borehole and the array will be filled with bentonite grout. The grout is intended to isolate the thermocouples by preventing hot gases from moving within the annulus. The surface at each array will be completed with an 18-inch thick concrete surface seal. A vertical support will be placed into the surface seal. A weather proof box will be attached to the vertical support. The thermocouple wire terminals will be accessed inside the box. The spine and thermocouple wires have been known to act as a preferred pathway for landfill gas. Gas leaking around the wires would be addressed with additional bentonite and/or soil.


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4 . 2 . 2 A d d i t i o n a l G a s I n j e c t i o n P o i n t A r r a y I n s t a l l a t i o n

Gas injection points (GIPs) will be installed using DPT drilling techniques. The injection points will be installed at a depth determined by the evaluation of vertical extent described in Section 4.2. The gas injection points will consist of a dedicated 2-inch diameter DPT drill tooling (pipe) with ¼- inch holes drilled around the bottom 10 feet of the pipe. The holes will be spaced at approximately 2 inches apart as shown in Figure 4 in order to not overly weaken the pipe prior to installation. The surface at each injection point will be completed with an 18-inch thick concrete surface seal with a minimum diameter of 18 inches. For injection and pre-injection gas sampling, the points will be fitted with a conversion from A-P drill thread to national pipe thread (NPT). The top of the injection point will be fitted with a “T” and a stainless steel, quarter turn ball valve followed by a connection compatible for a CO2 delivery hose. The other side of the “T” will be fitted with either a pressure gage and/or a self-sealing quick connect to allow a pressure measurements (and gas measurements) to be made using a GEM or similar instrument. The Bridgeton Landfill remedial team will coordinate with the CO2 supplier to determine what the final connection should be for compatibility with the tanker truck delivery hoses. The radius of influence of each point has been estimated, based on SCS’s experience with inert gas injection and anecdotal information from the industry, to be approximately 15 feet. The radius has been selected based on SCS’s anecdotal experience with inert gas injection at other sites, as there is no viable method to calculate a radius due to the variability of the waste over a small scale. Therefore, an array of injection points on a roughly 25-foot grid will be installed over the identified subsurface landfill fire event area. The grid will extend beyond the subsurface landfill fire event area, with a minimum of one injection point located outside the identified subsurface landfill fire event area on all sides. 4 . 2 . 3 Injection of Inert Gas

As described above, it is estimated that each GIP will have a radius of influence of approximately 15 feet. Each injection point will consist of a 10-foot long perforated section of pipe and is estimated to influence approximately 15 vertical feet. The estimated liquid CO2 utilized per injection point is 323 pounds of liquid CO2, which would generate approximately 2650 ft3 of gaseous CO2 at STP.

Liquid CO2 injection will be performed over a one-day period unless the array is too large to allow completion in one day. Liquid CO2 will be delivered to the site via tank truck or tank trailer. Access to the subsurface landfill fire event area suitable for the tanker truck must be prepared. At each GIP location, the liquefied CO2 supplier will connect directly to the GIP, and deliver approximately 323 pounds of liquefied CO2. Note that it will be difficult to determine the exact amount of liquid CO2 injected into each point due to the nature of the liquid CO2 delivery (via tanker truck); therefore, close attention will be paid to back pressure on the injection point, CO2 pressure influence, and temperature fluctuations on adjacent monitoring locations. The liquid CO2 will be targeted for injection at pressures between 200 and 300 psi measured at the injection point. This range has been selected because higher


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pressures have the potential for causing ground upheaval and at pressures lower than approximately 75 psi, the liquid CO2 may transform into a solid.

The injection will begin at the outer gas injection points and work inward to the center of the suspected combustion zone. This will minimize the potential for forcing heat outward from the combustion zone into adjacent areas. Special hazards associated with this work include the risk of suffocation due to the displacement of oxygen and the risk of frostbite from super cooled gas, hoses, and piping. A Health and Safety Plan will be prepared to cover inert gas injection activities and will be attached to this work plan prior to implementation. Up to four rounds of injections are anticipated under the following scenario:

Initial injection on the first day and monitoring overnight to determine the need for additional injection based on real-time monitoring of subsurface temperatures at the thermocouple locations, if installed.

Additional injection on the second day, as needed.

Temperature monitoring for one week and evaluation of the need for additional injection (this will include evaluation of the need for additional injection points).

Third injection within 24-72 hours of the second injection, if needed.

Weekly temperature monitoring for up to four weeks following the last injection.

If rebounding occurs above the trigger temperature after the third injection, a fourth injection will be implemented within 24-72 hours of the measurement of the temperature above the trigger.

Weekly temperature monitoring for up to four weeks after the final injection.

Subsequent injections following the first day should be targeted at specific GIP locations rather than repeated injections at all GIP locations. 4 . 2 . 4 Monitoring

Monitoring must be performed during injection. Monitoring must also be performed after the injection has been completed to evaluate the long term effect of the gas injection. 4.2.4.1 Injection Monitoring

The observer will look for any visual or audible signs of short circuiting; including surface cracking, gas release indicated by the discharge of soil particles or plumes of condensation from cold gas, or hissing noises. In areas where a surface membrane is present (such as the ethyl vinyl alcohol or EVOH liner covering a portion of the North Quarry), short circuiting could result in ballooning of the membrane, up to the point of rupture if sufficient gas pressure can accumulate in a limited area. It may become necessary to add soil on top of the membrane to prevent ballooning and hold the injected gas in the subsurface as long as possible. The areal extent of soil to be placed will be determined by site conditions. The membrane will be repaired after the completion of the inert gas injection. Potential leakage around the edges of the temporary cover and near thermocouple and injection points completed through the cover


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will also be monitored for VOCs using a hand-held FID and for CO2 using a Envision meter (or equivalent). Unused injection points will be monitored to ascertain if CO2 gas has extended to the adjacent points as well as to monitor the gas within the zone of concern. If they have been installed, temperature probes will be monitored prior to, during, and after each liquid CO2 injection round 4.2.4.2 Performance Monitoring

After liquid CO2 injection, the temperature points will be monitored for rebound of temperatures that may occur over the following month to determine the effectiveness of the liquid CO2 injection at suppressing the elevated temperatures at the site. Generally, temperatures are expected to either rebound to former higher levels or stabilize at the lower temperatures within several days after injection. Temperature readings will be recorded continuously at 1- hour intervals throughout and after the gas injection by the existing thermocouple array. The thermocouple data will be read continuously until a few hours after injection, at least daily for the next week, and on a weekly basis thereafter until it has been determined that temperatures have stabilized and there is little potential for re-ignition. The schedule shown in Figure 3 assumes that if a rebound occurs it will be identified within a week of the subject injection. In the event that elevated temperatures are not abated or temperatures rebound above the trigger temperature, a re-injection and/or expansion of the liquid CO2 injection area will be required as discussed in Section 4.2.3.

If rebound occurs after the fourth injection, other remedial approaches will be evaluated. If rebounding does not occur within four weeks following the second, third, or fourth injections, the fire will be considered to be extinguished and the operation of the landfill gas wells in the vicinity will resume normal operations.

5.0 RESPONSE TO TRIGGER VALUES AT DEPTHS GREATER THAN 40 FEET

5 . 1 CORRECTIVE ACTIONS TO BE COMPLETED WITHIN SEVEN DAYS

If a verified trigger value exceedance is measured in an existing, operating landfill gas well, a U-tube style cooling loop will be installed in the well, connected to the existing cooler, and operated within seven days of the trigger value exceedance. Details on the U-tube cooling loop system are provided in the Technical Evaluation of a Heat Extraction Barrier report, prepared by Feezor Engineering, Inc., November 2015. The existing well head will be removed and replaced with a well head that includes connections for both chilled liquid entry and exit and for the extraction of landfill gas. If the existing cooler cannot accommodate the additional load or it is not feasible to connect to the existing cooler, the construction of an additional cooler would be required. If the construction of an additional cooler is required, a revised schedule will be communicated to the US EPA and MDNR.


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Operation of the cooling loop will provide a measure of immediate heat removal while the location of the heat-generating zone is assessed. The effects of the actions taken during the first seven days will be evaluated during the remainder of the seven day period. This will include, but not be limited to, monitoring existing subsurface temperatures in TMPs in the vicinity of the trigger location, monitoring gas temperatures in the landfill gas extraction wells in the vicinity of the trigger location, and monitoring CO concentrations in the landfill gas extraction wells in the vicinity of the TMP (if the trigger occurred in a TMP), or in the impacted landfill gas well if the trigger occurred in a gas well.

5 . 2 CORRECTIVE ACTIONS COMPLETED AFTER SEVEN DAYS

A U-tube style cooling loop will be installed in all the wells within a 200-foot radius of the trigger location to the depth necessary to attempt to isolate and contain the event. These loops will also be connected to the existing cooler. An array of TMPs and combination cooling installations will be constructed around the TMP or gas well where the trigger value exceedance was recorded. At a maximum radius from the TMP/well of 50 feet, three TMPs will be installed. The TMPs will be spaced equally, 120 degrees from each other at the selected radius from the impacted TMP/well. The TMPs will be installed to an equivalent depth to where the temperature exceedance was measured in the impacted TMP or at a depth equivalent to the bottom of the screened interval of the impacted gas extraction well. The placement of the TMPs is illustrated on Figure 5. The construction of the TMPs is described in detail in the North Quarry Subsurface Temperature Monitoring Probes Work Plan, prepared by Feezer (2016) (TMP Plan). The TMPs will be installed using a bucket auger or sonic drilling rig. In addition to the TMPs, three combination cooling installations will be installed. The combined cooling installations will be placed at the same radial distance from the impacted TMP/well as the TMPs described above and will be placed in between the TMPs, at a spacing of 120 degrees rotated 60 degrees from the TMPs. The combination cooling installations will include three components: a cooling loop, a GIP, and a pressure relief point (PRP). These components will be installed in a 24 or 36-inch diameter borehole advanced with a bucket auger rig. As illustrated in Figure 5, the components will be suspended in the borehole and a gravel pack will be placed around them. The gravel pack will extend to within 20 feet of the landfill surface. The upper 20 feet of the borehole will be filled with a seal consisting of concrete or a combination of bentonite and concrete. The cooling loop will be a closed system, pipe within a pipe constructed of black steel. The inner pipe will deliver chilled liquid to the bottom of the outer pipe. The cooling liquid will flow back to the surface in the annulus between the inner and outer pipe, collecting heat from the liquid and/or gas in the gravel pack, which will collect heat from the surrounding waste mass. The cooling loop will be connected to the existing cooler or a newly constructed dedicated cooler if the existing cooler is located too far away or if it does not have the available capacity to handle the three new cooling loops.


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Operation of the cooling loops will provide some measure of immediate heat removal and containment while the location of the heat-generating zone is assessed. The amount of heat removed from the cooling loop will supplement the TMP measurements to locate the source of the heat-generation. In addition to the cooling loop, a GIP and PRP will be installed in the borehole. The GIP will be installed to a depth above the liquid level in the landfill as estimated from observations during drilling and from information on liquid levels measured in nearby gas extraction wells. Liquid CO2 will not be injected into liquid or into saturated waste to avoid potential negative impacts that could initiate or accelerate an event caused by an accelerated exothermic chemical reaction or reactions that are occurring under anaerobic conditions in saturated waste. Ongoing research being performed by Environmental Research & Education Foundation (EREF) indicates that elevated pressure is a potential trigger for these accelerated chemical reactions. This research also indicates that the increase in acidity that would likely result from introducing CO2 into saturated waste could also contribute to the initiation, acceleration, or expansion of an accelerated exothermic chemical reaction or reactions occurring under anaerobic conditions in saturated waste. The bottom 10 feet of the GIP will be perforated pipe. Because the GIPs and PRPs are being installed in a bucket auger borehole rather than being driven by a direct push rig, they will be constructed of 2-inch threaded black steel pipe. Based on SCS’s experience performing inert gas injection at other sites, the 2-inch diameter black steel pipe is sufficient to allow either liquid or gaseous forms of CO2 to be injected into the waste or to relieve pressure in the form of gaseous CO2. These deep GIPs will be completed at the surface in a similar fashion to the shallow GIPs described in Section 4.2.2 above. The bottom 10 feet of the PRPs will be perforated pipe. The bottom of the PRPs will be placed approximately 10 feet above the top of the perforated pipe in the GIP. The PRPs will be completed at the ground surface similarly to the GIPs without the connection for the liquid CO2 supply hose. 5 . 2 . 1 I n j e c t i o n o f I n e r t G a s

There may be situations where Bridgeton may decide that it is not advisable/feasible to inject liquid C02 into a combination cooling installation, for instance, when it is determined that the deep GIP is significantly below liquidIleachate levels in the combination cooling installation borehole. In this situation, Bridgeton will communicate the rationale to the EPA and the MDNR for concurrence. If the determination is made to inject liquid CO2 into the GIPs in the combination cooling installations, the injection will be performed as described in Section 4.2.3 above, with exception of any reduced injection that may become necessary to control pressure in the PRPs as further discussed below. 5 . 2 . 2 I n j e c t i o n M o n i t o r i ng

Monitoring during injection will be performed as described in Section 4.2.4.1 above. In addition, the PRP will be monitored for pressure. If the pressure exceeds a value calculated from the depth of the GIP in feet, times 0.4 psi/ft (the estimated pressure resisting uplift at the


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bottom depth of the GIP based on an assumed density of waste of 58 lbs/cu ft and injection depth of 40 feet), the PRP valve will be opened to keep the pressure at or below the calculated target maximum pressure. If there is positive gas pressure in the GIP, Bridgeton Landfill will evaluate, in consultation with US EPA and MDNR, whether a higher maximum pressure should be implemented for the operation of the PRP. 5 . 2 . 3 P o s t I n j e c t i o n M o n i t o r i n g

The TMPs installed around the trigger location will be read daily for at least three weeks after the last injection of inert gas into the GIPs and data reported weekly. Other monitoring in the area, including membrane condition, settlement, and sampling for CO, will be performed on the schedule presented in Bridgeton Landfill’s OM&M Plan. Bridgeton will report the results of measurements taken on a daily basis to US EPA and MDNR on a weekly basis. A report of other measurements made on a frequency less than daily will be reported to US EPA and MDNR on a monthly basis. Weekly status reports will be prepared as described below in Section 8.0. 5 . 2 . 4 C o o l i n g L o o p A c t i v a t i on

The cooling loops will be activated either as soon as completed if a determination has been made not to inject inert gas, or one week after the injection of inert gas. If cooling loops are not ready to be activated for more than two weeks after the injection of inert gas, Bridgeton will consider an additional round of inert gas injection. 5 . 2 . 5 T M P A r r a y M o n i t o r i n g

The TMP array installed around the trigger location will be monitored weekly, consistent with the TMP Plan. In addition to the temperature monitoring in the TMPs, the gas quality in the landfill gas extraction wells in the vicinity of the trigger location will be monitored monthly, consistent with NSPS requirements. Settlement in the vicinity of the trigger location will be evaluated quarterly per the March 2018 OM&M Plan, Volume 1 – General Requirements and Surface Systems, which contains Table 2, entitled Proposed Data Collection. Per Table 2, North Quarry settlement surveys are conducted on a quarterly basis and the information is provided in the Monthly Report. Note that, should the rate of settlement at two adjacent points exceed 1.0 feet in a quarterly monitoring event, the survey frequency will be increased to monthly for the points in question and all adjacent points until the quarterly differential is confirmed to be less than 1.0 feet.

5 . 3 PERFORMANCE EVALUATION

After the heat extraction system, including the cooling loops installed in the combined cooling installations and the cooling loops installed in existing gas extraction wells, has been operating for a sufficient period of time its performance will be evaluated to see if the impacted area is controlled. (The term “controlled” is used in this context to mean that the conditions in the impacted area are not spreading and are stable or improving within the area of impact.) If it has had a measurable impact on subsurface conditions, to the point where both subsurface in situ waste temperatures and gas temperatures have fallen below the trigger levels, Bridgeton


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will discuss with US EPA and MDNR whether the heat extraction system will be turned off on a test basis. If the operation of the heat extraction system does not reduce the temperatures below the trigger values or the temperatures continue to increase, other remedial approaches will be explored in consultation with US EPA and MDNR. Other remedial approaches will include, but are not limited to:

An expansion of the heat extraction system by the installation of additional cooling loops in the impacted area.

An expansion of the heat extraction system by the installation of leachate extraction wells in the impacted area.

Other approaches to be identified.

6.0 SCHEDULE

Bridgeton will notify the MDNR and US EPA of an initial exceedance of a trigger value within 24 hours of the measurement or receipt of the laboratory result. Bridgeton will notify the MDNR and US EPA of a confirmed exceedance of a trigger value within 24 hours of the measurement or receipt of laboratory result. Those actions that will be performed within seven days do not require any additional detail.

6 . 1 CORRECTIVE ACTIONS COMPLETED AFTER SEVEN DAYS FOR TRIGGERS AT DEPTHS LESS THAN 40 FEET

Following a trigger exceedance and the initial seven day actions, additional efforts to verify the lateral and/or vertical extent of the shallow impacted area/subsurface landfill fire event area will be performed. The schedule is presented in Figure 3. This effort will, at a minimum, entail monitoring gas composition and temperature in gas extraction wells in the area, observation for further impacts to the cover, and surface temperature monitoring. It may also include the design, installation of, and evaluation of the data from an array of shallow subsurface TMPs. Following the evaluation of the data collected on the horizontal and vertical extent of the subsurface landfill fire event area, the array of GIPs will be designed and installed. The gas injection(s) will begin upon completion of the GIP array. Performance monitoring to verify that the SSO has been successfully remediated will be performed for at least one month after the last round of gas injection has been completed. As described in SOP Section 17, an initial investigation will commence within 12 hours of the observations of symptoms of a potential subsurface landfill fire event. The actions described in SOP Section 17 will be implemented within 24 hours of the determination that a subsurface landfill fire event is present.


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6 . 2 CORRECTIVE ACTIONS COMPLETED AFTER SEVEN DAYS FOR TRIGGERS AT DEPTHS GREATER THAN 40 FEET

The schedule for the corrective actions to be completed after the initial seven days for trigger exceedances at depths greater than 40 feet is presented in Figure 6. Within the two weeks following a trigger exceedance, a bucket auger rig and/or a sonic rig will be mobilized to the site. While either type of rig may be used, the sonic rig is better suited to installing TMPs. The sonic rig creates a smaller diameter borehole and brings up a much smaller volume of solid waste cuttings that have to be disposed of. The bucket auger rig creates a 24 or 36 inch diameter borehole that is better suited for the installation of the combined cooling/injection wells, which require the installation of multiple pipes surrounded by a gravel pack and seal. Bridgeton will maintain contact information for a number of drilling firms that can provide either or both bucket auger rigs or sonic rigs. This will facilitate identifying a firm with rigs available to respond within the target time frame. During the mobilization time, any access roads and/or pads for the drilling rig will be constructed. The drill rig will install the combination cooling installations first, to allow the grout to set up before any CO2 is injected, followed by the installation of the TMPs. It is estimated that the installations will be completed in two weeks. During the drilling and construction of the combination cooling installations and the TMPs, the piping needed to connect the cooling loops in the combination cooling installations to the existing cooler will be constructed. If a stand-alone cooler has to be constructed to serve the cooling loops, a revised schedule will be developed and communicated to US EPA and MDNR.

7.0 MATERIALS, CONTRACTORS, AND VENDORS

Bridgeton Landfill maintains a stockpile of soil on site to support the immediate implementation of the cover and smother effort. Bridgeton Landfill has on site or has quick access to the excavation, hauling, grading, and compacting equipment and the personnel on site to place additional soil as needed. Bridgeton Landfill will keep on site the materials needed to install the initial shallow GIP and to construct a GIP array sufficient to address a shallow impact area with a diameter of 100 feet (total of 20 GIPs). To be conservative, the quantities listed in Table 1 assume that the GIPs will be installed to a 40 foot depth. Bridgeton Landfill will keep on site the materials needed to install nine shallow temperature probes to facilitate the delineation of a subsurface landfill fire event and/or monitor the impact/performance of shallow inert gas injections. The shallow TMPs would each include up to six thermocouples spaced at 5 or 10 foot intervals vertically. It is not feasible to maintain sufficient quantities of liquid CO2 on site in anticipation of a trigger exceedance. It is unlikely a fixed tank would be located where it would be needed and it would not be feasible to convey the liquid CO2 by hose over possible long distances from the fixed tank to the injection point. It is also not feasible to keep a direct push drilling rig on site in anticipation of a trigger exceedance.


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Bridgeton Landfill will keep on site a pre-assembled well head that will allow the addition of a U-tube style cooling loop to an existing landfill gas extraction well that has experienced a trigger value exceedance. Bridgeton Landfill will keep on site the materials needed to construct the three deep TMPs, three deep GIPs, three pressure relief points, and three cooling loops. The completed depths of the TMPs and cooling loops are conservatively estimated at 150 feet. The TMPs will incorporate thermocouples at intervals of 10 to 20 feet vertically. As indicated above, the construction of TMPs is described in detail in the North Quarry Subsurface Temperature Monitoring Probes (TMPs) Work Plan (TMP Plan) dated December 2016. The depth of the deep GIPs will be determined by the depth to water data available for the area of impact. An estimated depth of 50 feet has been assumed for material estimation purposes. The pressure relief points will be at least 20 feet shallower than the deep GIPS, and so are estimated at a depth of 30 feet. The deep GIPs will be constructed of 2-inch threaded black steel pipe, couplings, and the various adapters, valves, and gages, etc., as will be needed to connect to the liquid CO2 source and to monitor the conditions during and after injection. The following contractors and vendors have been identified as potential members of the project team required to implement inert gas injection. Bridgeton will have agreements with these companies to allow them to respond rapidly enough to implement inert gas injection within seven (7) days. Bridgeton reserves the right to select other firms of equivalent quality and experience. The specific entities selected will depend on schedule and availability at the time of the project. Liquid CO2 Vendors Airgas Cryogas 3500 Bernard Street 5835 Manchester Avenue St. Louis, MO St. Louis, MO 866-935-3370 (314) 655-0077 (314) 603-2655 Praxair, Inc. 6701 St. John Ave. Kansas City, MO 64123 1-800-PRAXAIR (772-9247) (816)242-6741 Drilling Subcontractors Recovery Drilling Services, LLC REDI P.O. Box 53, 157 West Main 1107 S Mulberry St. Dudley, MA 01571 Millstadt, IL 62260 (508) 943-1182 (618) 476-7334 Injection Program Design


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SCS Engineers 2060 Reading Road, Suite 200 Cincinnati, OH 45202 (513) 421-5353 Injection Program Implementation and Monitoring

SCS Engineers 13 Executive Drive, Suite 1 Fairview Heights, IL 62208 (618) 628-2001

8.0 REPORTING

Weekly status updates will be provided via email throughout the period for implementation of this Work Plan. Weekly status updates will continue until the impacted area has been extinguished or controlled. Status updates will include discussion of on-site activities during the previous week, summary of data and findings, and planned activities for the following week. Data for which multiple readings/measurement are performed/collected over time and are amenable to tabulation will be submitted in either Excel or comma separated text files. The status updates will be provided by close of business on Monday of the following week.

A Post Inert Gas Injection Event Summary Report will be submitted if Inert Gas Injection is performed at the Site. The report will generally include the following items:

Summary tables of all data collected during and following or otherwise associated with the event;

Narrative section discussing the date, time, and general nature of the event, the initial response(s), and text describing response actions and regulatory notifications made;

Decision tree steps followed including resulting actions taken to fully monitor/address the event; and

Discussion of the overall injection process following an event, including discussion of all ongoing monitoring or responses to the event.

The Post Inert Gas Injection Event Summary Report will include a draft submittal and a final submittal, with the draft version being submitted to the US EPA and the MDNR within 60 days following an injection event.


1

F i g u r e s

FIGURE 1. ORGANIZATION CHARTBRIDGETON LANDFILL REMEDIAL TEAM

Direct Push Drilling Inert Gas SupplierSonic DrillingBucket Auger Drilling

ManagementContractualOversightCoordination of on site activities

SPECIALTY SUBCONTRACTORS

ENVIRONMENTAL MANAGERProvides daily manangement of of the implementation of the OM&M Plan, including the IGI plan

ENVIRONMENTAL SPECIALISTSResponsible for implementing the OM&M Plan, including the IGI Plan at the field level. Perform regular monitoring.

OPERATIONS MANAGER

Bridgeton LF or third party personnel who perform

OM&M activities in the field.

DIVISION MANAGERPrimary person responsible for implementing OM&M

Plan, including IGI Plan.

CONSULTANTSConsultants evaluate data; design GIP, TMP, and/or CCIP arrays; provide 3rd party oversight of drilling and gas injection; evaluation of monitoring results; and reporting.

Responsible for implemenation of the OM&M Plan, including the IGI Plan, including coordination of day‐to‐day activities.

FIELD TECHNICIANS

4‐24‐18

Trigger

185ºF wellhead gas temp or

1500 ppm CO in

200ºF in

Perform regular monitoring of gas wells

for temperature and CO and the TMPs

for temperature

Figure 2: Trigger Exceedance Decision Tree

Take additional readings to verify trigger exceedance within one

calendar day, while notifying the EPA/MDNR of initial exceedance.

Notify within 24 hours:

• Advance RTD Probe into all gas wells with 300’ radius of trigger location to

determine approximate temperature profile within two business days.

• Take daily field measurements as defined in Table 1 of the TMP Work Plan.

• Collect SUMMA samples on any gas wells within 300’ radius of trigger

location to determine CO levels within two business days and monthly

thereafter.

• Immediately shutdown any well(s) within 300’ radius that have elevated

temperature profiles based on RTD Probe.

Find the maximum temperature

above 40 feet and below 40 feet.

Is the overall maximum

temperature greater than 40 feet

deep?

Monitor heat extraction system and

terminate once condition is controlled

based upon consultation with the U.S.

EPA and the MDNR.

TMP Installation

• Install up to 3 TMPs 120°/ 50’ radius around

the triggered TMP/gas well

Corrective Action to Complete within 7 Days

A.) The Bridgeton Landfill will install U-Tube heat extraction

units in gas wells within 200’ of trigger location.

B.) Connect heat exchangers to cooling tower and start heat

extraction.

C.) Resume gas extraction at wells that had been shutdown.

Evaluate performance of initial corrective

actions for the remainder of the 7 days,

ensuring that temperature readings are

representative of surrounding landfill

temperatures.

Corrective Action to Continue After Initial 7 Day Response Period

Combined Heat Extraction/Injection Wells

• Obtain depth to leachate levels

• Drill 3 combined heat extraction/injection

wells 120°/50’ radius around triggered TMP/

gas well. (Install injection points above the

leachate level.)

Inject inert gas in the combined injection well

above the leachate level with no greater

pressure than 0.4 psi/vertical foot

After a time delay based upon temperature readings,

activate the cooling element in the combine heat

extraction/injection well (During or before the time delay,

run header line and connect to cooling tower)

Monitor TMP Array weekly, and Settlement and Gas Quality Data monthly.

Is the newly installed heat extraction network adequate to mitigate heat?

Corrective Action to Complete within 7 Days

A.) Schedule previously contracted driller/installer and confirm supplies

per ASAOC.

B.) Cap or repair any item identified during the physical inspection that

may be contributing to oxygen intrusion

C.) Carefully add additional cover to area that show cap integrity

issues if necessary.

D.) Subject to direct push rig availability, insert injection points into area

of SSO evidence based upon visual observations

E.) Mobilize contracted CO2 vendor.

Corrective Action to Continue after Initial 7 Day Response

Period

Evaluate performance of initial

corrective actions for the remainder of

the 7 days.

If there is no additional exceedance,

resume (continue) normal operation of

Gas Extraction System

If 4th round of gas

injection is not successful, explore

other remedial

approaches

Determine the extent of affected area

Continue to observe for visual

symptoms

and/or

Install and monitor shallow TMP

network

Install network of injection points

Inject inert gas

Injection monitoring

Performance monitoring

Is exceedance still occurring or is rebound observed?

Initial inert gas injection

• Immediately shutdown well(s) that are believed to be

the cause of the exceedance.

Additional remedial approaches will

be explored based upon consultation

with the U.S. EPA and the MDNR.

Contact/Secure within 24 hours:

Drill Rigs

Installers

Other 3rd party contractors and suppliers

YES

NO

YES

Key of acronyms

• TMPs: Temperature Monitoring Probes

• CO: Carbon Monoxide

• ASAOC: Administrative Settlement

Agreement and Order on Consent

• MDNR: Missouri Department of Natural

Resources

• USEPA: United States Environmental

Protection Agency

• RTD: Resistive Thermal Device

• CO2:: Carbon Dioxide

• PSI: Pounds per square inch

Is the exceedance verified?

• If the temperature is greater than

185ºF above and below 40 feet,

both pathways will be taken.

Frequently monitor well(s) for three

weeks

Contact EPA/MDNR within 24 hours to explain why initial exceedance wasn't verified and what actions

have been taken.

NO

YES

YES

NO NO

YES NO

NO

FIGURE 3. SCHEDULE FOR POST 7‐DAY ACTIONS FOR TRIGGERS AT DEPTHS LESS THAN 40 FEET

WeeksTASK 1 2 3 4 5 6 7 8 9 10 11 12Notification of Verified Trigger Exceedance X

Activities to be accomplished in 7 days

Install shallow TMP array.

Continue surface observations

Evaluate TMP readings & design GIP array

Install GIP array

Inject CO2 into GIPs, perform injection monitoring1

Post injection monitoring and performance evaluation1

Note 1: This schedule assumes that only 1 round of inert gas injection will be performed. The schedule will extend by approximately 2 weeks for each subsequent round of inert gas injection.

Revised 11/22/16

4

AutoCAD SHX Text

DRILL 1/4 IN. %%C 2 IN. O.C.

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WITH 1 IN. OFFSET

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PERFORATION DETAIL

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EVERY 90%%d

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(NOT TO SCALE)

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2 IN.

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90

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2 IN. DIA. DPT DRILL PIPE OR BLACK STEEL PIPE

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FIGURE 3

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GAS INJECTION POINT PERFORATION

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13570 ST. CHARLES ROCK ROAD

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BRIDGETON, MISSOURI 63044

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BRIDGETON LANDFILL

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SCALE:

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DATE:

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CADD FILE:

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PROJ. NO.

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2060 READING ROAD SUITE 200 CINCINNATI, OHIO 45202

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PH. (513) 421-5353

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CONSULTING ENGINEERS, INC.

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SCS ENGINEERS

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N.T.S.

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April 2018

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PERF DETAIL

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23211003.04

TMP TMP

TMP

COMBINED

COOLING / INJECTION

POINT

COMBINED

COOLING / INJECTION

POINT

COMBINED

COOLING / INJECTION

POINT

50'

TRIGGERED TMP

OR GAS WELL

1

2

0

°

36''

COMBINED COOLING / INJECTION WELL

-cross section-

Pressure Relive

Valve

Vent

Cooling element

Inert

Gas

Seal

10'-15'

Injection point

will be installed

above leachate

level

APPROVED BY: ---

NOVEMBER 2016

REVISION DATEPROJECT NUMBER: BT-121 FILE PATH:

DRAWING NO.: Figure 5

D:\Dropbox\BT-121\Working\combined Cooling_injection Well_conceptual Drawing.dwg

DESIGNED BY: IN

CONCEPTUAL DRAWING FEEZOR

BRIDGETON LANDFILL, LLC

13570 ST. CHARLES ROCK ROAD

BRIDGETON, MISSOURI 63044

BRIDGETON LANDFILL

NORTH QUARRY AOC

COMBINED COOLING /

INJECTION WELL

FIGURE 6. SCHEDULE FOR POST 7‐DAY ACTIONS FOR A TRIGGER AT A DEPTH GREATER THAN 40 FEET

WeeksTASK 1 2 3 4 5 6 7 8Notification of Verified Trigger Exceedance X

Activities to be accomplished in 7 days

Mobilize drilling rig

Construct access roads and pads for drilling rig as needed.

Drill and install combination cooling installations and TMPs1

Mobilize CO2 supplier X

Construct piping to connect cooling loops to existing chiller unit2

Perform CO2 injection and injection monitoring

Post injection monitoring and performance evaluation1

Begin operation of cooling loops in combination cooling intsallations3 X

Notes:1. Install combination cooling installations first and TMPs second to allow for grout to cure before CO2 injection.2. A revised schedule will be prepared if a stand‐alone chiller will have to be constructed to serve the combined cooling installations.3. Cooling loops in combination cooling installations will operate until termination criteria is achieved.

Revised 12/13/16


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A p p e n d i x A B r i d g e t o n L a n d f i l l S O P S e c t i o n 1 7 , S u b s u r f a c e O x i d a t i o n

E v e n t s

Landfill Gas ManagementOperations and Maintenance

Standard Operating Procedures

Page 17-1 October 9, 2015Version 2.0

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Because subsurface oxidation (SSO) events are serious situations that could potentially damage large areas of the landfill, generate odors, and create community concern, discovery of an SSO must be immediately reported to the Environmental Manager (EM) and the Landfill Operations Manager and immediate steps must be taken to remediate it and minimize its impact on the Gas Collection and Control System (GCCS) and landfill.

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The following symptoms are indicative of an SSO:

' Dramatic localized landfill settlement' Charred or cracked surface cover' Stressed or dead vegetation in an area that is otherwise properly vegetated ' Smoke or smoky odor emanating from the landfill surface or wellhead ' Drastic or unusual increase in flowing gas temperature' Significant drop in methane content in the gas' Abnormal discoloration of wellhead/riser assembly' Abnormally high carbon monoxide (CO) and ammonia (NH3) concentration in landfill gas (LFG)' Deformed riser pipes

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If any of the signs of a potential SSO are detected, the EM and Landfill Operations Managershall be immediately notified. The EM shall also notify the AEM, DEEM, and Manager,Landfill Gas Operations within 24 hours of discovering the SSO or if an SSO is suspected butnot yet confirmed.

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An initial investigation of the situation should include the following:

1. Health and Safety

a. The first step in investigating a suspected SSO must be to ensure the proper healthand safety measures are in place.

b. A number of additional hazards may be present when an SSO occurs, includingexposure to hazardous compounds in smoke or fugitive gas emissions, unstableground surface due to subsurface subsidence or collapse, potential flames, and others.

2. Do not attempt to douse or flood the wells or area of the suspected SSO with water.

Bridgeton Landfill




3. Individuals responding to or investigating an SSO should take the following safetyprecautions, at a minimum:

a. Consult the site (or project) health and safety plan (HASP) for procedures related tolandfill fires and SSOs.

b. Under no circumstances shall an initial investigation be conducted without firstconsulting the HASP and implementing appropriate controls and procedures.

c. Utilize a minimum of two people during investigations of suspected SSO events.

d. Do not breathe landfill gas or smoke. Stand upwind of any emissions.

e. Wear appropriate PPE. Burns may be caused by hot PVC/HDPE/steel.

f. Do not drive heavy equipment or vehicles near wells or any surface depressionsuntil ground stability has been verified. The burned waste mass may give way andequipment/personnel may fall into the sinkhole.

4. Do not change the condition of the LFG extraction wells/collectors.

5. Personnel shall conduct a physical inspection that includes the following:

a. Inspect the nearest extraction well to the suspected SSO location.

b. Inspect all wells within 500 feet of the nearest extraction well to the suspected SSOlocation.

c. Inspect the landfill surface within 500 feet of the nearest extraction well to thesuspected SSO location.

d. Visually inspect for large localized settlement, cracks, holes, collapse, missingcomponents, or areas that could be sources of air intrusion into the waste mass:

i. Monitoring portsii. Well casing

iii. Geomembrane boots at wells or other componentsiv. Hosesv. Erosion ruts/rills

vi. Dry soil cracksvii. Manways

viii. Lift stationsix. Sumpsx. Leachate cleanout risers

Bridgeton Landfill




6. Measure gas quality, pressure and temperature at all wells within 500 feet of the nearestextraction well to the suspected SSO location. Special precautions may be necessary toaddress high gas temperatures.

7. Measure CO concentrations with colorimetric stain tubes (Draeger or Sensidyne tubes) atall wells within 500 feet of the nearest extraction well to the suspected SSO location.

a. Gas temperature and interference gases can affect the accuracy of the measurement;therefore, the results of any CO monitoring should be expressed qualitatively only.

b. Cheehp mn[^ fZgn_Z\mnk^kzl bglmkn\mbhg hg ma^ nl^ h_ ik^-filters and/or carbon pre-tubes to minimize the impact of potential interference gases.

8. Infrared (IR) Thermometer Survey w Use an IR laser thermometer to measure the temperature of the ground surface in the area of the suspected SSO. Shallow fires or fires that have consumed large amounts of trash will produce elevated surface temperatures. Extreme caution must be taken in these areas due to the potential for the ground to give way.

+1(. 74H4 4B4@MG=G

To determine the state of the SSO, the following should be performed or evaluated:

1. Obtain carbon monoxide samples using colorimetric stain tubes.2. Temperature gradient between monitored wells.3. Oxygen gradient between monitored wells.4. Balance gas (or nitrogen (N2) if measured directly) to oxygen (O2) ratio gradient between

monitored wells.5. Pressure gradient between monitored wells.6. Methane (CH4) to carbon dioxide (CO2) ratio gradient between monitored wells.

Analytical data on the gas in the wells in the vicinity shall also be collected using either Tedlarbags or pre-evacuated SUMMA canisters. The analysis shall include fixed gases (CH4, CO2, O2,and N2), CO, and ammonia. Other compounds may be added if necessary. Take samples offlowing gas, not stagnant gas.

+1(/ F8ACJ=B; GCIF68G C9 CLM;8B

The key to stopping an SSO once it has begun is to completely restrict oxygen from entering thesmoldering waste mass (i.e., snuff it out). Once the initial investigation has been performed anda general sense of the extent of the SSO has been determined, safely begin to restrict furtheroxygen intrusion using the following method:

A. Shut down any wells that are believed to have been the cause of the SSO. Shut down anywells in the area with elevated balance gas measurements, which would be indicative of oxygen intrusion into the refuse. Complete Startup, Shutdown, Maintenance (SSM) forms as necessary.

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B. Shut down all wells in the surrounding area (within approximately 300 feet of the suspectwell(s)). Complete SSM forms as necessary.

C. Cap or repair any item identified during the physical inspection that may be contributingto oxygen intrusion.

D. Carefully add additional cover soil to areas that show cap integrity issues, if necessary.Work slowly and pay special attention to the ground surface as material placementcommences.

1. During cover placement activities there should be a minimum of two peopleavailable: the equipment operator and a line-of-sight person on the ground that isresponsible for watching the ground surface as the equipment operator places the soil.

2. Use a low ground pressure (LGP) machine, if available. If an LGP machine is notavailable, use the lightest machine with the widest tracks available. Do not userubber tired machines to place cover material.

3. Slowly push soil into the area and compact with the bucket or tracks of theequipment.

E. Note: Closing wellhead valves to minimize vacuum in the area of concern may causevacuum levels to increase within the main header if the GCCS is not operated on vacuumcontrol. This will redistribute the overall vacuum applied to the wellfield and may causehigher vacuums to other wells in the GCCS. Carefully watch for redistribution ofvacuum, and adjust the blowers/prime mover vacuum set point accordingly. If greaterthan 10 percent of the total wells in the wellfield are closed to remediate the SSO, acomplete retune of the wellfield may be warranted.

+1(0 H<=B;G HC 4JC=7

1. Flushing the well with water. Flushing the well with water can potentially clog the well.It will also generate steam, pressure, and odor when water hits the SSO area.

2. Excavating soil in the SSO area. Do not excavate in the SSO area. Excavation will allowadditional oxygen to enter the already smoldering waste mass and can potentially cause itto auto-ignite.

3. Venting. Do not remove the wellhead to vent the well. Wellfields are typically undernegative pressure. Residual vacuum may exist in the waste mass for a period of timewhen wells are closed. If the wellhead is removed to vent, it is highly possible that theresidual vacuum in the area will pull ambient air into the waste mass, adding oxygen tothe SSO.

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4. Dry ice application. While dry ice may have a temporary cooling effect on the physicalwell casing, it will have little to no effect extinguishing the SSO. In addition, in order toapply dry ice to a well, the wellhead must be removed, which would provide oxygen apathway to enter the waste mass (see above).

5. Introduction of water into open landfill cap or cover soil fissures. Applying water toopen fissures in the cap where an SSO exists can create a plume of highly odorous steamand could potentially impact slope stability. It is also dangerous to bring a heavy, rubbertired water truck to the area to apply water. The steam created can be dangerous toworkers in the immediate area. If an open cap fissure exists in an SSO area, follow theprocedure for placing cover soil described above. Removing the pathway for oxygenintrusion is the most effective way to extinguish the SSO.

+1(1 6CBH=BI87 ACB=HCF=B;

Site personnel or the Operations, Maintenance, and Monitoring (OM&M) Provider should visually monitor the area of the suspected SSO at least once per day until the SSO has been fully remediated. In addition, the wells closest to the SSO area and adjacent wells should be monitored once per day for two weeks. The wells should be monitored for gas quality, temperature, and CO.

As the SSO subsides, residual CO will remain in the waste mass for weeks and possibly months.Elevated CO levels are not a reliable indicator that an SSO is still in progress. However, COlevels should generally decline with time if the oxidation has been terminated.

Once SSO indicators are no longer detected, the EM, AEM, and DEEM should conduct a conference call to discuss the sequence in which wells will be reopened and review the data to ensure the SSO has been extinguished. The wells in the SSO area and the adjacent wells should be monitored daily for at least 4 months before returning to a normal monitoring schedule.

+1(2 F8D4=FG

Repairs should be made to the SSO area, as necessary. The OM&M Provider shall visuallyinspect the following, as listed in Section 18.3, at a minimum:

' Wellheads and lateral piping' Cover soil and geosynthetics' Other items within the SSO area

Findings and repair options shall be forwarded to the EM and Landfill Operations Manager whowill facilitate repairs, as appropriate.

+1(3 H=A8@=B8

It is important that a structured SSO monitoring plan and diligent adherence to the plan becarried out to return the wellfield to SOP operations as soon as possible. However, it is

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advisable to take time and slowly ensure the SSO is fully extinguished, and that the anaerobicbacteria population in the area has recovered and is consistently producing gas.

The severity of the SSO, the age of the waste, moisture content, and a number of other variableswill all determine how long it takes the wellfield to regain compliance with the SOP. Experiencehas shown that the timeline from the point when the SSO is identified and extinguished to thepoint when the wellfield resumes normal operations can vary from 2 to 3 weeks up to (in someserious SSO situations) 1 year or more.

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