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Continuous Gas Monitoring

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1 Continuous Gas Monitoring
Good Morning Ladies & Gentlemen, My name is Glenn Young and I supervise the Closed, Illegal and Abandoned Site program at the CIWMB This morning/afternoon, I would like to cover Continuous Gas Monitoring System and their application to structures on or near disposal sites. Ideally I would like to ensure that this session on continuous gas monitoring provides LEAs with substantive tools they can use to help them at sites where landfill gas migration is impacting structures. Continuous Gas Monitoring Glenn K. Young, P.E. Senior Waste Management Engineer

2 Overview Background Regulations System Overview Components & Cost
System Installation/ Operation & Maintenance Implementation Summary Today, although I am armed with 38 slides and only have 25 minutes—I will try to hit the high points for continuous gas monitoring: I will cover some background on the evolution of automated control and remote sensing and its applications to continuous landfill gas monitoring. I will do a brief summary of the important points from our landfill gas regulations regarding continuous monitoring I will provide you with a general overview of a continuous gas monitoring system, the components and their costs, system installation and operation and maintenance. I will provide you with some implementation tools such as workplan, drawings, specifications, vendors and consultants and wrap up the presentation with key highlight to take away. The contents of this presentation including a list of vendors, distributors, example plans and specifications are loaded on a CD which will be available to all conference attendees and eventually will be available on the CIA website under the phase II field investigation webpage.

3 Background Postclosure Land Use/Residential & Commercial Development of former disposal sites Safety regulations (OSHA) drive industrial requirements for monitoring hazardous conditions (Petroleum and natural gas industry), which drove sensor technology development Development of Direct Digital Control (Automatic) technology in 1980s to monitor and control building and utility systems for energy conservation Combustible gas monitoring applied in industrial settings for safety purposes Combustible gas monitoring applied in residential and commercial settings due to 27 CCR Landfill Gas Monitoring and Control requirements and Brownfield and industrial development Background: Just a review of how automated gas detection systems used in industry (chemical manufacturing, petroleum and natural gas industry) can (and has been) applied to structures on or near landfills and disposal sites. Key events: -PCLU and development of old disposal sites -Safety regulations for gas detection in place for activities which store, transport & handle combustible gases -Direct Digital Control Automation Systems developed in 1980s to control energy use -Combustible Gas Detection systems in place in natural gas industry -Continuous monitoring required in 27 CCR Article 6 (Gas Monitoring and Control Regulations) and 27 CCR 21190

4 Gas Measures at PCLU projects
Example of PCLU project where gas monitoring and control measures occurred as part of the construction of a Home Depot on an old disposal site in Marin County. The facility was constructed with a membrane liner and continuous gas monitoring system which were tied to an alarm and ventilation system in the building. Additionally a gas control system was operated within the landfill.

5 Regulations Federal Regulations (40 CFR Part ) Explosive Gas Control State Regulations (27 CCR Article 6) 27 CCR Gas Monitoring & Control Regulations (a) 1 Explosive Gas Control. 20921 Gas M&C During Closure/PC 20931 Structure Monitoring 20934 Reporting 20937 Control 21190 Postclosure Land Use Of course it’s important to know the statutory authority requiring continuous monitoring systems, which are found in both Federal and State regulations: Generally Subtitle D requires gas monitoring and control and 27 CCR Article 6 Gas Monitoring and Control Requirements ( ) Continuous gas monitoring is also discussed in the Postclosure Land-use Section 21190

6 Regulations 27 CCR (a) 1 Explosive Gas Control “…owners…must ensure that: (1) The concentration of methane gas generated by a (MSWLF) facility does not exceed 25 percent of the LEL for methane in facility structures…” 20921 (a) (1) requires that “…The concentration of methane gas must not exceed 1.25% by volume in air within on-site structures…” 20931(a) “…monitoring network design shall include provisions for monitoring on site structures, including but not limited to buildings, subsurface vaults, utilities or other areas where potential gas buildup would be of concern…” 27 CCR (a) states that a facilities near landfills will not exceed 25 percent of the LEL; This is important because controls and actions will be taken if concentration levels reach 25% of the LEL or 1.25% So the key is control is required for structure exceeding 1.25% (so how do figure this out—is the question)

7 Regulations 20931(c) “…Structures located on top the waste disposal area shall be monitored on a continuous basis..” 20934 (a)(1) “…monitoring reports shall include: (1) the concentrations of the methane….within each on-site structure…” 20937 (a)(3) “…the documentation of date, time, barometric pressure, atmospheric pressure, general weather conditions and probe pressures…” Further regulations require: Continuous monitoring b)Monitoring reports for each on-site structure c)Documentation of date, time, barometric pressure, etc. etc. Sounds like an automated data collection system? Not unless you Want to permanently place a 40-hr trained student assistant with a Combustible Gas indictor in locations at a site where gas may accumulate

8 Regulations 20937 Control (d) “…When the results of monitoring in on site structures indicate levels in excess of those specified in Section 20923(a), the operator shall take appropriate action to mitigate the effects of landfill gas accumulation in on site structures, and public health and safety, shall include one or more of the following:…(4) Alarms, …(5) Ignition source control…(7) Ventilation…” 20937 requires that operators will take appropriate action to mitigate the effects of landfill gas accumulation in on site structures using alarms, ignition source control and ventilation. These are all controls which are easily performed by automated facility systems.

9 Regulations 27 CCR a) Proposed PCLUs shall be designed and maintained to: …(3) prevent landfill gas explosions…” 27 CCR e) “…Construction of structural improvements on top of landfilled areas…shall meet the following conditions:…(1) automatic methane gas sensors, designed to trigger an audible alarm when methane concentrations are detected, shall be installed in all buildings…” 27 CCR e) (8) periodic methane gas monitoring shall be conducted inside all buildings…” Finally, the Postclosure land-use section states that any proposed construction of structures on or within 1000 feet of a disposal site (within the parcels encompassing the disposal site) shall be constructed with a continuous gas monitoring system and appropriate controls.

10 System Overview Landfill Gas Migration Routes Sensor Locations
Continuous Gas Monitoring System HVAC Control Interface Let’s do the big picture overview of gas migration from a typical landfill and see how a continuous monitoring system may be applied to structures on or near an old disposal site.

11 Landfill Gas Migration Routes
Just wanted to point to a few things on this diagram: LFG migration dependent on subsurface geology, but also surface development, e.g. facilities, pavement, etc Personnel who work on water wells, underground utilities, excavations, etc are also at risk from gas migration

12 Gas Migration Routes Gas migration into structures constructed on top of waste may occur, even if engineered “precautions” (utility boots, geomembranes, well bore seals, utility seals, etc) are taken, because differential settlement is difficult to predict for the life of the structure, e.g. predicting areas of settlement due to surface loading (as well as waste consolidation due to inherent waste properties (decomposible content, voids, compaction, etc). The key is to identify susceptible areas and spaces and to monitor them for landfill gas migration. The above photos highlight the sometimes unpredictable nature of settlement on a landfill (the owner, when he constructed the facility felt that the engineering would account for settlement—after 20 yrs in the facility, numerous projects to correct settlement damage, he no longer shares the view that settlement issues can be accounted for through appropriate engineering methods—and the only method I know of that works for sure is to remove the fill material and replace with engineered fill)

13 Gas Migration Paths Belmont shores mobile home park in Long Beach suffers from High concentations of methane in the fill Mobile homes with “raised” foundations Differential settlement impacting cap integrity (cracks) and potential gas migration paths

14 Gas Sensor Placement Any accessible confined spaces near a landfill where a 5-15% LEL-UEL condition would most likely occur Structures on or within 1000 feet of the landfill (homes, buildings, warehouses, etc) Basements, subfloors and raised foundations Utility systems: manholes, vaults, boxes and subsurface trenches, storm drains, water & electrical distribution in the vicinity or through the disposal area Utility closets, mechanical rooms, bathrooms (utility penetrations) Water wells, excavations (pools) Sensors should be placed in facilities and utilities near disposal sites were gas migration is occurring Spaces where landfill gas may accumulate: Basements Subfloors Utility Systems (storm drains, drainage structures) Wells

15 Gas Sensor Placement An example diagram of a warehouse constructed on top of a landfill: Locations of sensors at 14th Avenue Warehouse: Offices, subfloors, enclosed structures, utilities penetrations, warehouse activities where ignition sources were present

16 Continuous Gas Monitoring System
This diagram shows primary components of a continuous gas monitoring and control system The sensors are placed in locations where gas may accumulate The sensors transmits a 4-20 mA signal (representing between 0 and 5% gas) The controller receives the 4-20 mA signal and can perform several operations (based On programming from a PC with appropriate software), which includes: a) recording The signal for a specified period and frequency, b) triggering an alarm or control based On a programmed setpoint, e.g. the 25% of the LEL; the control may be to activate a Facilities ventilation system, which typically operated under direct digital control systems. The system requires power, but typically the power (120 V/60Hz) is converted to 24 VDC A relay, electric switch or solenoid valve can be turned “on” or “off” based on logical rules programmed into the controller (normally via PLC software) For instance the following statement could be programmed as a logical rule: If the gas sensor signal is equal to or greater than 12,500 ppm (25% of span), then store data at current time and turn on alarm relay and fan relay (ventilation system) in full outside air mode.

17 Bldg Monitoring & Control Systems
This shows, how a building’s ventilation system can be tied to a controller based on programming the controller to relay an analog output signal to a ventilation control (either switch or relay to turn on HVAC unit or fan unit), given an input signal condition of “25% of lower explosive limit condition met (setpoint)”. This sequence of sensing and control based on “control rules” is knows as programmable logic control (PLC).

18 Components & Costs Sensors Controller Data Loggers PC-interface
Gas Sensor Let’s talk about Continuous Monitoring System Components and their costs Note the happy engineer with his trusty laptop! Data Logger PC-Interface

19 Gas Sensors Detects presence and measures concentrations of combustible gas Generally CGI instruments calibrated to “known” gas (methane) Catalytic Bead or Infrared (IR) Sensor IR sensors do not require oxygen Explosion Proof Housing 24 VDC Power to Sensor/Transmitter 4-20 mA Analog Output Signal Wall mounted NEMA 4X Enclosure Wireless models available Cost: $300-$1500/sensor Gas Sensor key notes: -sensor detects methane using either Catalyic Bead or IR technology (IR does Not require oxygen) -sensors transmit a 4-20 mA analog output signal to a controller -wireless transmitters are available and can significantly simplify installation requirements -sensors are manufactured by several companies and run between $300 and $1500 a sensor (depending on capabilities and features)

20 Gas Sensors (CG/LEL) Biosystems GasChek1 ($2295) Scott GasPlus-IR
GDS M-1 Here are some example sensors: Some examples of sensor manufacturers include: Scott, RKI, GDS, Biosystems and Safe T net RKI PS-2 Single Point ($425) Safe T Net Model Ch

21 Gas Sensors (CG/LEL) Biosystems GasChek/Catalytic Bead/EXP ($995)
More example sensors: Note: most sensors are similar in features; explosion proof sensors tend to be more expensive due to a heavier duty housing which protect the sensor interior electronic components Probably not important to specify and explosion proof housing—if an explosion has occurred—it’s too late To send a signal to turn on ventilation or alarms BW Gas Point Sensor RKI Eclipse Sensor Catalytic ($550) RKI S-Series Catalytic

22 Controllers Controller used to “receive” 4-20 mA sensor (transmitter) analog output signal, store in data acquisition unit (if present), and control “output” devices such as alarms, electric switches, solenoid valves or other “controls”, e.g. turn-on heating, ventilation and air conditioning system (HVAC) Controllers are microprocessor based and programmable (but require software and a PC interface). Controllers require power source (120V/60-hz) Controllers are wall-mounted in weatherproof NEMA 4X enclosures Controllers can be single or multichannel (typical: 4, 8, 10, 16, 32 and up (cost increases); for a typical closed disposal site with commerical or residential structures a 16-channel should suffice Controllers generally cost between $500-$3500 Controllers are the brains of the continuous gas monitoring system. You have a controller in your house—it’s called a Thermostat, which regulates the temperature in your house by sensing temperature in the target space and turns the air conditioning or heating on or off to meet a user defined temperature setting. The controller receives the 4-20 mA signal and uses programmed logic to control specified operations, e.g. turn on and off (using electric switches, relays, solenoids) analog systems alarms, fans, etc. Controllers can be single or multichannel (each sensor has a dedicated channel); for example a 4-channel Controller receives signals from 4 sensors. Controllers typically run from $500-$3500 and may or may not include software, memory and PC

23 Controllers RKI BL-7000 PEMTECH 16-Ch PT-1008 8-Ch RKI Beacon 800
Here are examples of multi-channel controllers RKI Beacon 800 8-Ch ($1995) GMI Active 8 8-Ch

24 Controllers BW CR-8700 8-Ch SMC Sentry 8-ch CR-9600 96 Channels
Note the single channel controller manufactured by Gas Tech. An advantage of this type of design is it can fit into a “rack” which has a multichannel controller; This allows the system to be expandable. CR-9600 96 Channels ANTX 40-Ch Gas Tech 1-Ch

25 Data Loggers (Data Acquisition)
Loggers provide memory to store data points produced by 4-20 mA measurements (gas concentration measurement normally 0 to 5% Vgas/Vair) taken by gas sensor Loggers can be programmed to query and store data at user defined timepoints and frequencies, e.g. 1 measurement per hour, 24 hrs per day, 7 days per week, 365 days per year. Logger programs can output data to spreadsheets for documentation and data analysis, e.g. graphical representation (measurement versus time) for time trend analysis Provides documentation and defensible evidence for determining 1.25% in structures and 5% at the perimeter boundary. Data loggers are dedicated memory. Each data point stored based on PLC programming which specifies time and frequency. Data loggers are generally interfaced to PC’s to determine period and frequency of measurements.

26 Data Loggers (Data Acquisition)
Manufacturers: Logic Beach, Omni Instruments, DataQ, HOBO, WebDAQ, Yokogawa, MadgeTech Data Logger may require: software for PC interface, additional memory, modem, wireless transmitter (these are not included in base unit cost) Data Logger requires power (120V or 24V source), phone line connection Data Loggers with multichannel capability, PC interface software, memory and modem can run between $1500 and $3500 See The Data Logger Store: Data loggers provide the “memory” for continuous gas monitoring systems to download gas cnoncentration measurements taken by the sensors. The data loggers must be interfaced through PC software to provide instructions for duration and frequency of gas concentraton measurements.

27 Loggers (Data Acquisition Units)
Logic Beach HyperLogger ($3000) DataQ DI-710 ($1400) Here are examples of data logger units by various manufacturers. We used the Logic Beach Hyperlogger at Newport Terrace which Abel will be talking about. Omni DAQ 4000 Logger (695 British Pounds) WebDAQ 100 ($1295)

28 System Installation Power source (120 V/60 Hz) required to operate data logger, controller, sensor and PC interface (if on-site); power consumption is nominal; Battery back-up required Standard telephone connection (modular jack) required to data logger for remote data access and downloading Sensor should not be placed in a corrosive environment or subject to irrigation waters, although designed for outdoor use Sensors can be used in constucted “probe vaults” to simulate utility boxes Wireless systems should be used if feasible to minimize installation costs Ensure receivers and transmitters are “line-of-site” without obstructions Locate antennas as high as possible in structures Purchase and use signal repeaters if signals are weak For systems where “hard-wiring” is used: Cable runs should consider subsurface utilities and landscaping (cost increases with burying cable in areas with pavement, landscape and utilities) Conduit may be considered for cables in common areas or potentially subject to traffic or vandalism; 12 inch direct burial of cable is acceptable (per NEC) Cable runs need to meet voltage drop requirements based on length of run and cable or wire size (generally 1000 feet or less for No. 12 AWG) Sensor should be “clustered” if possible to minimize installation disturbance Some key notes on system installation: You need to provide 120 V/60 Hz power to sensors, the controller and data logger units. Generally continuous gas monitoring systems do not use much power, e.g. the power is generally stepped down to 24 V direct current or VDC. Thus these system do not incur much of a electric utility cost. You can go cable installation or wireless. Cable installations are difficult at sites with “dense” paving and utility infrastructure (electrical, water, communications, gas, irrigation, etc). Be prepared to spend money on cable installation as it is time intensive, even “out-of-the-ground” wiring requires labor for running wire in conduit. Also, hardwire systems are limited by voltage drop, so if long runs are being considered, e.g. greater than 1500 feet, signal loss may be a problem. Wireless is very promising since the costs for hardwiring can be done for a fraction of the equipment costs necessary for wireless adapting equipment. The only downsides are frequency interference and potential loss of data for unspecified periods (however this could happen with hard wire systems as well due to power outages). The upside is signal transmission as great as one mile line of site. With either system it is important for the user to track the system’s status and respond to any system failure or malfunction as necessary (within days—certainly not weeks or months).

29 System Installation Here is an example of hardwire installation (Abel will be discussing the Newport Terrace site). Note that there was a great deal of utility corridors to deal with, especially due to the density of utilities associated with condominiums.

30 System Operation & Maintenance
System should be calibrated once per quarter or if erroneous readings are detected during monthly download System data should be downloaded monthly or as required based on memory size and data collection frequency (24-hr, 7-day, 365-day is typical) System requires a dedicated phone line and power supply (with separate circuit and breakers). Most systems come with back-up battery to maintain data; however power restoration is critical The key for Ops and Maintenance is regular inspection, calibration and a regular data download schedule. (a daily system check for the first two weeks; a weekly check for the first two months and a monthly check thereafter). Ensure that consultants include this type of specification when developing continuous monitoring workplans. Also, any sensors impacted by environmental conditions, e.g. flooded due to irrigation and drainage, should be replacef ASAP (effort should be placed in the design phase to ensure that this does not happen). “Zero-Span” Calibration

31 System Operation & Maintenance
System maintenance and operations will be be the same for most equipment; Primarily: Checking power Ensuring gas sensors and controller are caibrated properly Checking on system to ensure continuous operation

32 Implementation Drawings & Specifications Consultants & Contractors
Equipment Manufacturers Equipment Distributors Implementation: The key things you will need to provide an RP who knows little about continuous gas monitoring systems is: Consultants who design, specify and install gas monitoring systems (for more complex applications, e.g. several facilities at a disposal site) Equipment vendors and distributors who manufacture, distribute and install continuous monitoring systems (for relatively straight-forward applications (a single residence, a trailer home, a target structures) Example work specifications, drawings and schematics that describe the work and equipment needed to install, maintain and monitor A knowledge of potential costs to install gas monitoring equipment

33 Drawings & Specifications
Here is an example drawing with notes (Newport Terrace). It shows the locations of sensors, The construction of probe vaults and has notes regarding the installation of the controller and Logger.

34 Consultants & Contractors
SCS BAS (Bryan A. Stirrat & Associates) URS TetraTech Ninyo-Moore Here are some consultants that work on landfill gas monitoring systems. Each company has a long history of consulting on landfill gas monitoring in California and should be up to speed on regulations, requirements and the design, specification and installation of continuous gas monitoring systems.

35 Equipment Manufacturers
ATI Biosystems BW Technologies Crowcon : Det-Tronics Drager General Monitors GDS Corp GMI Industrial Scientific LandTEC Manning Systems MSA RAE Systems RKI Instruments Scott Instruments Sensidyne Sieger Sierra Monitor Corp (SMC) Thermo-GasTech ZellWeger This is a list of equipment vendors who sell gas sensors, controllers and loggers for methane gas.

36 Distributors A-L Compressed Gases http://www.alcompressedgases.com/
Industrial Safety Equipment & Supplies Jensen Instrument, Co. Davis Instruments This is just a few distributors that distribute fixed gas detection systems in California.

37 Summary Automated or Direct digital control systems have been in use for over 20 years and if properly calibrated and maintained are reliable, efficient and cost-effective Systems can provide time-trend gas monitoring data that is accurate and legally defensible (can be used to show 1.25% by volume in air levels for enforcement purposes) Difficult to demonstrate compliance with 1.25% rule In addition to monitoring, systems can be used to control alarms and ventilation, which would directly protect public health and safety System components (sensors, data acquisition systems, controllers, etc.) can be purchased off the shelf from numerous manufacturers Summary, the technology for monitoring and documenting gas conditions within structures has been around for over 20 years, but primarily in the industrial sector. This same technology can be used to provide defensible evidence (time-trend data) of an exceedance of 1.25% in structures triggering a gas control remedy. The technology can also be used to remedy “combustible conditions” in A structure by turning on the ventilation system (or a subslab venting system). Numerous manufacturers produce fixed gas detection equipment—the equipment is off-the-shelf. .

38 Summary Cost of continuous gas monitoring system (<$50K) is substantially less than typical landfill gas extraction and treatment systems ($500K-$1.5M), e.g. if project costs are to be prioritized the first remedy would be to implement a continuous monitoring system in structures to protect public health and safety. For example a wireless continuous monitoring system with 10 sensors would cost 10 $1000/sensor or $10K 1 each 16-channel $4500 or $4.5K 1 each data $3000 or $3.0K 10 wireless transmitters and $5K Design and Installation Cost $10K Total system cost: $32.5K Continuous monitoring systems should be designed, specified and installed by qualified individuals A maintenance and monitoring program are integral to ensuring defensible documentation as well as protection of public health and safety through automatic control systems (automatic ventilation systems). Fixed gas detection systems are relatively inexpensive compared to landfill gas control systems

39 Summary Continuous systems should be “designed”, specified and installed by a qualified and experience consultant and contractor Continuous monitoring systems must be operated, calibrated and maintained to minimize the risk of gas migration into structures and protect public health and safety


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