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HomeMy WebLinkAbout4407_Haywood_WhiteOakMSW_Revised_LFGMP_FID1390244_20200218Explosive Gas Monitoring Plan White Oak MSWLF Haywood County, North Carolina i• 'SS1n +9 '°' 439455 ;Figure 2 was revised February 2020 zCT.d SANTEK LVAVA WasteServices November 2016 GARRET]r & MOORE �■ !2; Engineering for the Power and Waste Industries 1100 Crescent Green Drive, Suite 208 Cary, North Carolina 27518 • O: 919-792-1900 • F: 866-311-7206 NC FIRM C-2910 Explosive Gas Monitoring Plan White Oak MSWLF Contents 1.0 Introduction............................................................................................................... 1 2.0 Permanent Landfill Gas Monitoring Wells.................................................................1 3.0 Landfill Gas Monitoring Locations.............................................................................1 4.0 Landfill Gas Monitoring Equipment............................................................................2 5.0 Landfill Gas Detection in Wells..................................................................................2 6.0 Landfill Gas Detection in Structures.......................................................................... 2 7.0 Landfill Gas Monitoring Observations........................................................................3 Figures Figure 1 — Landfill Gas Monitoring Well Detail Figure 2 - Explosive Gas Monitoring Plan Monitoring Locations Forms Landfill Gas Measurements Field Worksheet, White Oak MSW Landfill, Haywood County, North Carolina TOC 1 Explosive Gas Monitoring Plan White Oak MSWLF 1.0 Introduction The Haywood County White Oak MSWLF will monitor quarterly for methane and other explosive landfill gases within the landfill structures and at the landfill gas monitoring wells. 2.0 Permanent Landfill Gas Monitoring Wells The permanent landfill gas monitoring wells (monitoring well) will consist of a plastic stand pipe similar to a piezometer used for groundwater detection. A typical permanent landfill gas monitoring well is detailed in the attached Figure 1. The permanent probe will be constructed at a minimum depth of six (6) feet. A minimum 6" diameter hole will contain a one (1) inch slotted PVC pipe. The bottom two (2) feet will be backfilled with non - carbonate pea gravel with a bentonite seal one (1) foot thick above it. The remaining three (3) feet will be backfilled with in situ soils. The one (1) inch PVC pipe will be approximately three (3) feet above the existing grade. The PVC pipe will be capped with a one (1) inch PVC cap, one quarter (1/4) inch NPT hose barb, and 1" tubing, plugged or capped to prevent contamination. A minimum four inch (4") diameter schedule 40 PVC sleeve or aluminum/steel prefabricated well cover will be placed over the one inch (1") pipe and filled with clean masonry sand to within four inches (4") of the one inch (1") schedule 40 PVC cap. The top of the PVC pipe sleeve or prefabricated well cover will be secured with a removable water tight cap. Where necessary, a marker post will be placed in close proximity to the landfill gas monitoring well. A permanent well I.D. will be placed/painted on the marker post or the well cover. 3.0 Landfill Gas Monitoring Locations The migration of methane and other explosive landfill gases (landfill gas) is induced by pressure gradients. The landfill gases will move from areas of high pressure to those of low pressure following the path of least resistance. Landfill gas will generally migrate vertically until it reaches the landfill surface where it may begin to flow horizontally until it finds a pathway out through the permeable in situ soils or a landfill gas venting/extraction system. Given that Haywood County's landfill is designed with a synthetic membrane base liner system there should be no landfill gas migration into or through the subsurface permeable in situ soils. The final cap system, once designed and installed, will also contain a synthetic membrane liner system with a landfill gas venting/extraction system. This type of cap system will also prevent the migration of landfill gas into or through the surrounding permeable in situ soils. Since methane, a component of landfill gas, is lighter than air, it wants to escape into the atmosphere. Experience has shown that whenever gas is migrating no matter what the spacing or depth of the monitoring probes, the gas will fill the void created by the Page 1 Explosive Gas Monitoring Plan White Oak MSWLF monitoring well and an explosive gas detection meter will monitor the level of concentration. The six foot depth of the monitoring wells is to ensure a stable monitoring point. The only time a shallow monitoring well has not worked is in a very heavy, impermeable clay layer that acts as a seal to the migration of the gas. If a clay layer is encountered during the construction of a monitoring well, it will either be moved beyond the clay or excavated to a depth that is in the conductive zone below the clay. The location and spacing of the landfill gas monitoring wells as well as the on -site structures include the Maintenance Building and the Scale House are shown on Figure 2. 4.0 Landfill Gas Monitoring Equipment The landfill gas can be detected by use of an instrument that reports the percent of lower explosive limit (% LEL) and the methane gas concentration (% CH4). The instrument being used is the LandGEM 2000. 5.0 Landfill Gas Detection in Wells Quarterly the Haywood County landfill will monitor for methane and other explosive landfill gases at the landfill gas monitoring wells as shown on attached Figure 2. If landfill gas is present and the level is detected at or above the lower explosive limit (100% LEL), it must then be determined if the landfill gas is migrating or has migrated beyond that particular monitoring well. If it is determined that explosive landfill gas has or may have migrated beyond the particular monitoring well then additional steps may be implemented to delineate the extent of any suspected landfill gas migration. If it is determined that explosive landfill gas has or may have migrated across the landfill boundary then the facility will immediately take all necessary steps to ensure protection of human health. The North Carolina Department of Environment Quality (NCDEQ) will be notified. Within seven (7) days of detection, the methane gas levels detected and a description of the steps taken to protect human health will be placed in the operating record. Within 60 days of the detection of suspected landfill gas migration at or beyond the landfill boundary, the County will prepare and implement a remediation plan for the suspected landfill gas releases. A copy of the remediation plan will be placed in the operating record and the NCDEQ will be notified that the plan has been implemented. Resampling of the affected landfill gas monitoring wells will be performed as necessary to evaluate the effectiveness of the approved remediation plan. 6.0 Landfill Gas Detection in Structures Quarterly the Haywood County landfill will monitor for methane and other explosive landfill gases at on -site structures. Currently, the on -site structures include the Maintenance Building and the Scale House as shown on attached Figure 2. Each structure will be Page 2 Explosive Gas Monitoring Plan White Oak MSWLF monitored for explosive landfill gas using the following general protocol: 1. All crawl spaces will be monitored; 2. All corners in the structure will be monitored; 3. Any observed holes, cracks and/or pipe penetrations through the foundation will be monitored; If methane gas is detected above 25% of its lower explosive limit (25% LEL) in any structure, excluding gas control or gas recovery system components, the monitoring technician will verify the field calibration of the detection instrument in accordance with the manufacturer's instructions and the structure will be resampled. If the reading is still above 25% LEL, evacuate the building and take all steps necessary to protect human health. NCDEQ will be notified as well as the Haywood County Solid Waste Director. Within seven (7) days of initial detection, the methane gas levels detected and a description of the steps taken to protect human health will be placed in the operating record. Upon taking the necessary safety precautions, attempt to determine the source of the explosive gas. If the source is found, initiate repairs to prevent re -infiltration of the landfill gas or remove the source. If the source of the landfill gas infiltration cannot be easily determined and/or promptly corrected then the structure must be closed and marked to prevent further occupancy. The County will then prepare and implement a remediation plan for the suspected landfill gas releases within sixty (60) days of initial detection. A copy of the remediation plan will be placed in the operating record and the NCDEQ will be notified that the plan has been implemented. The structure will remain closed for occupancy until such time as the repairs and/or remediation plan have been implemented and the structure retested for the presence of landfill gas concentrations. The structure will be reopened for occupancy once the landfill gas concentrations are below the 25% LEL concentration. 7.0 Landfill Gas Monitoring Observations Observations for the landfill gas monitoring wells AND for the on -site structures will be recorded on the attached form titled "Landfill Gas Measurements Field Worksheet, White Oak MSW Landfill, Haywood County, North Carolina". Page 3 Figure 1— Landfill Gas Monitoring Well Detail SAMPLING PORT WELL CAP (NOT CEDED) f � r � f X I M i r WELL TAC (INCLUDE THE FOLLDWINC INFORMATION) _ WELL ID.: DRrLLING COMPANY: DATE OF INSTALLATION: TOTAL DEPTH: CONSTRJuTION DETAILS: 3' 4a4' L(XKABLE STEEL CASING (3' WIN_ STICK UP WITH LOCKING COVER) CAP AND SAMPLING PORI "—PERFORATED PVC RISER CONCRETE 1-140 "-- BENTO °I TE PELLET SEAL (HYDRATED PER MFG. SPECS) GRWT SEAL (CEMENT AND SODIUM BENTONITE) SEDIMENT SEASONAL HIGH WATER TABLE 13 --�,- \LPL-� STREAM (TYP.) LFG-7 \ SEDIMENT BASIN #5 SEDIMENT BASIN #1 SEDIMENT BASIN #7 LFG-8 LFG-9 LFG-4R �' �,� LEACHATE LA \ I SEDIMENT BASIN #6 LFG-10 \ 4II / ° LFG-2 \ I \ "-PHASE \�4.4 AC) I PHASE 3 I I LFG-1 I �� (P.8 ACRES) KZ I HASE 7 I f� PHASE 5\\ (9.9 AC) \ I UTURE I r (11.4 ACRES) LANDFILL I I / DEVELOPMENT I 14.3 AC I SEDIMENT BASIN #4\\ (10 1ASE ACRES) PHASE 6 �\ / �I \� \� EDIMENT LCID /(4.8 ACRES) LANDFILLFUTURE `DEVELOPMENT _-/ SCALE AND SC 16.2 AC /� TRUCK TIRE WASH 1 \ I CLOSE[) -- C & D �\ �� TYRE COMPbSG ' 1 PHASE 1 �, �I (1.2 AC /(4.0 ACRES 701 1 rr- 1 /INEN� N C E BUILDIN BASIN #2 ALE HOUSE 4 ISEDIMENT BASIN #3 _ MULCHING AND GRINDING TREATMENT AND PROCESSING (2.0 ACRES) HAYWOOD COUNTY WHITE OAK MSWLF PROPERTY LINE Landfill Gas Monitoring Field Worksheet White Oak MSW Landfill Haywood County, North Carolina Name of Person Taking Readings: Weather Conditions: Atmospheric Pressure: Gas Monitoring Equipment: Factory Calibration Date: Date: Ambient Temp: Serial #: Field Calibration Date: Well or Probe ID Stable Readings Time % LEL % CH4 % CO2 % 02 Notes *Note: If methane gas reading exceeds 25 of LEL in structures or 100% of LEL in probes contact Haywood County Solid Waste Director immediately.