Outline. The Federal Regulations. Why Do the Tier-2 Testing?

Transcription

1 Outline John V. Fontana, PG President/CEO, Vista GeoScience Golden, Colorado 2016 Annual Conference SWANA - Colorado Rocky Mountain Chapter October 3-5, 2016; Keystone, Colorado Some History The EPA Regulation Composition of Landfill Gas Non-Methane Organic Carbon (NMOC) EPA Method 25c & 3c Evolved Method Modifications Early Inefficiencies Advent of Direct Push Drilling QC - On Site Analysis of CH 4, CO 2, O 2, N 2 Post-Run Tubing Methods Composite Sampling Methods (Summa Canisters) Hazards and Safety Concerns to Investigators The Federal Regulations 1996, March Clean Air Act (CAA) Regulations for MSW because of the concern to public health and the environment. Regulations require that MSW landfills 2.5 million Mg and 2.5 million cubic meters or more of waste - must collect and control if their estimated emissions of NMOCs are 50 Mg/yr or more. (NEW RULES: 34mg/yr) Thermal treatment of NMOCs and methane through flaring or combustion in an engine, turbine, boiler, or other device greatly reduces the emission of these compounds. Tier-2 Testing is used to determine the NMOC emissions Required after 5 years and every 5 years thereafter. Why Do the Tier-2 Testing? SO, if you fit the size requirement, (at least 2.5 million Mg and 2.5 million cubic meters in size) but do not exceed NMOC emissions of 50 Mg/yr, you do not need to collect and control or treat the landfill gas. Smaller landfills do not want to spend the money on a collection system if its not required. Cost of measuring the NMOC content every 5 years and showing it is below 50 Mg/yr outweighs the cost of installing a collection and treatment system

2 Typical Landfill Gas Components Component %Volume Atmospheric Concentration methane ppm carbon dioxide ppm nitrogen % oxygen % ammonia Trace NMOCs (nonmethane organic compounds) Trace Sulfides (incl. H 2 S) 0 1 Trace hydrogen ppm Production Phases of Typical Landfill Gas carbon monoxide Trace Modified from: Tchobanoglous, Theisen, and Vigil 1993; EPA Non-Methane Organic Compounds (NMOCs) NMOCs are organic compounds (i.e., compounds that contain carbon). Nearly 30 organic hazardous air pollutants (HAPs) and volatile organic compounds (VOCs), React with sunlight to form ground level ozone (smog) if uncontrolled. Exposure to these pollutants can lead to adverse health effects. NMOCs may occur naturally or be formed by synthetic chemical processes. Most commonly found in landfills include: acrylonitrile, benzene, 1,1-dichloroethane, 1,2-cis dichloroethylene, dichloromethane, carbonyl sulfide, ethyl-benzene, hexane, methyl ethyl ketone, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride, and xylenes. Beyond the NMOC Other hazards exist to the Tier-2 Investigator Tier-2 Sampling Requirements (EPA Method 25c) Collect & Analyze Samples by EPA Method 25c Soil Gas Probing Method, Collection in Canisters Analysis by EPA Method 25 and EPA Method 3c Two Soil Gas Probe Samples per Hectare 1 Hectare = 2.47 Acres = Minimum spacing of 53,800 sq ft, or 230 sq. grid) Up to 50 Sample Points Maximum Distributed Evenly Over Landfill

3 EPA Method 25c Procedure for Sampling and Measurement of NMOC as Carbon (reported as hexane) Specific Tooling Required Many requirements have been modified by documented approved alternatives Analysis of NMOC Gases (Method 25) QC - Fixed Gases, O 2 -CO 2 -CH 4 -N 2 (3c) to determine percent air dilution in samples. EPA 25c Method: Summary Insert a probe perforated at one end 3 feet below bottom of landfill cover. Composite Sampling Allowed Field Analysis of N 2, O 2, CO 2, CH 4 to determine how much air dilution Analysis per Method 25 for NMOC Unique method by Gas Chromotograophy - separates NMOC from CO, CO 2, and CH 4. Oxidizes NMOC to CO 2, reduce to CH 4, analyzed on FID detector, reported as ppm hexane. Sampling performed only by experienced personnel EPA 25c Method: Required Equipment Stainless Steel Probe bottom 1/3 perforated Threaded Sampling Cap Sampling Train Rotameter w/ Flow Control Valve Sampling Valve (Stainless) Pressure Vacuum Gauge (1 mm Hg, or 0.5 Hg, resolution) Sample Tank (stainless or aluminum) Vacuum Pump Purging Pump Pilot Probe (0.25 smaller than sampling probe) + Post Driver Auger (if you can t drive a probe) Pea Gravel and Bentonite to seal the probe NMOC Analyzer Barometer, Thermometer (and Syringes) Method 25c Diagram of Purging Setup

4 Method 25c Diagram of Sampling Setup Approved Alternatives Initially promulgated methods did not reflect recent technology advances and were very inefficient. Many Approved Alternatives have been posted that allow the method to be modified Modified Combined Sampling System Designed to Minimize Air Introduction Approved Alternative: Geoprobe Drilling Rigs Faster Probing & Sampling Self Sealing Driven Probe Rod, Greater Depths Post Run Tubing (PRT) System

5 Collecting Soil Gas Samples Using PRT System Sampling Train Expendable or Retractable Pt. Inner tube inserted after driving rod. Reduces potential leak points Probes can be driven to greater depths, below multiple landfill cap layers c Quality Control Approved Alternative: QC using O 2 vs. N 2 Nitrogen can remain high in some landfills, especially in arid environments. QC Requirement: >20% N 2 assumed to be air dilution from a leak; SAMPLE IS REJECTED. Many landfills have >20% N 2 but <1% O 2 If N 2 is from Air, we should see >5% O 2. Alternative: If N 2 is high, but O 2 <5%, then SAMPLE IS VALID

6 Sampling Method Calibrate Alimeter/Barometer Calibrate CO 2 -O 2 -CH 4 Gas Meter Check Sample Train for Leaks Using Vacuum Probe Test Hole Location Insert PRT with Stainless Adaptor and Teflon Tubing Insure Seal Around Probe Connect Tubing and Valve Assembly w/ Filter/Water Trap Calculate System Volume (Tool, Tubing, etc.) Connect Gas Meter Sampling Method (Cont.) Purge Test Hole ml/min. max. flow rate Using Landtec GEM Gas Meter Pump Look for stable CO 2 and CH 4 reading Record Timing & Purge Volume Est. volume using avg. flow rate x time. More Precise Use Vacuum Drop in Canister Test Gas Composition Using Gas Meter & Record CO 2, O 2, CH 4, N 2 (balance) N 2 Balance must be <10% (safety factor of 10%) OR, O 2 must be < 2.5% (safety factor of 2.5%) If N 2 or O 2 is too high, check system for leaks, offset, or probe deeper. Measure Summa Canister Initial Vacuum Pressure Need to know elevation for initial vacuum pressure & vol. A completely evacuated Summa will reflect atmospheric pressure. (ex psi at sea level) and will hold 6 Liters (at that pressure) Some labs partially fill canister with He, to allow non hazardous shipping. Sampling Method (Cont.) Collecting Composites in Summa Canisters 25c Requires 1 Liter Minimum for Composites Most accurate way to measure is by vacuum pressure drop, NOT by flow rate and time! You must leave a partial vacuum, 5-10% of total volume. Completely evacuated Summa holds 6 Liters. Partially He Filled Summa has room for 3 Composites. Calculate volume / unit pressure for 1 liter min. Divide remaining vacuum pressure by 4 Ex. 20 Hg /4 = 5 Hg for each sample Make sure this volume > 1 Liter Collect each sample by measuring pressure drop equally for each sample collected

7 Sampling Method (Cont.) Open Summa valve, Flow at <250 ml/min. (25c requires <500cc) Close valve periodically to check vacuum drop and calculate volume collected. Record Start/Stop time, pressure and flow rates Record ambient pressure (absolute, not corrected) Surface Air Temp, Record down-hole temperature (in probe or hole) Remove probe and plug cap with hydrated bentonite or clay cap materials Record GPS of location Minimal decon of rods required, unless liquids were contacted. Documented Calibration Logs and Sampling Notes Recorded Data Tables Google Earth is our Friend! GPS recorded locations shows even distribution across fill

8 Hazards to Investigators Intrusive Investigation into Capped Cells Under Positive Pressure Gas will flow from drill/probe holes and expose investigators Main Hazards Anaerobic Gases: Carbon Dioxide (asphyxiation hazard) Methane Gas - Physical Hazard, LEL = 5% Hydrogen Sulfide Gas EXTREME TOXIC HAZARD Deadly at ppm levels. Hydrogen Sulfide Gas (H 2 S) Short Term Exposure Limit (STEL) = 15 ppm Time Weighted Average (TWA) = 10 ppm IDLH = 300 ppm Other Notable Features: We can smell as little as 5ppb ppm loss of sense of smell Creates false sense problem is gone 500 ppm - loss of consciousness, respiratory arrest 1000 ppm - Unconscious in 1 breath, death 5 min Health & Safety Planning Where is it likely to occur? What engineering controls do I have available? Wind direction, ventilation, borehole and rig orientation Breathing equipment (SCBA, Escape Packs) Full Face with Acid Cartridges NOT ACCEPTABLE Is my electronic equipment intrinsically safe? Is my equipment spark resistant? Muster points Emergency Exits Rescue Plan Alarm Systems Site-specific orientation and HASP Use Upgraded Landtec We are doing an intrusive investigation that may discover H 2 S on site for the first time. Check with Landfill Personnel if H 2 S exists, but still be prepared if they say it has not been encountered before. Use Upgraded Landtecs with H 2 S Sensors (Plus Model) for Soil Gas and Monitoring Requirements

9 Personal Gas Monitors Never Rely on Smell! Reliable Way to Measure Ambient Concentrations Maintain Calibrations Audible Alarms Generally set at 10ppm Summary 1. Do it Right 2. Do it Safe Safely Collect Accurate NMOC Gas Samples for Tier-2 Regulations with H 2 S Present John V. Fontana, PG, President/CEO JFontana@VistaGeoScience.com Vista GeoScience, Golden, Colorado 2016 Annual Conference SWANA - Colorado Rocky Mountain Chapter October 3-5, 2016 Keystone, Colorado 35