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HomeMy WebLinkAboutSW_F_2301_MSWLF-1990_02-07-2014_SP_AOCleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page i TABLE OF CONTENTS 1.0 BACKGROUND ........................................................................................................ 1 1.1 LANDFILL SITES .......................................................................................... 1 1.1.1 West Site .............................................................................................. 1 1.1.2 East Site ............................................................................................... 2 1.1.3 Self-McNeilly Site ............................................................................... 2 1.2 SITE GEOLOGY AND HYDROGEOLOGY................................................. 2 1.2.1 Regional Geology ................................................................................ 2 1.2.2 Site Geology......................................................................................... 3 1.2.3 Site Hydrogeology ................................................................................ 5 1.3 REGULATORY LIMITS ................................................................................ 6 2.0 LANDFILL GAS MONITORING ........................................................................... 7 2.1 EXISTING MONITORING LOCATIONS ..................................................... 7 2.1.1 West Site .............................................................................................. 7 2.1.2 East Site ............................................................................................... 8 2.1.3 Self-McNeilly Site ............................................................................... 8 2.2 STRUCTURE MONITORING ....................................................................... 9 2.3 MONITORING FREQUENCY ....................................................................... 9 3.0 LANDFILL GAS MONITORING PROCEDURES ............................................ 10 3.1 DETECTION EQUIPMENT ......................................................................... 10 3.2 LANDFILL GAS MONITORING PROCEDURE ....................................... 10 4.0 RECORD KEEPING AND REPORTING ............................................................ 12 4.1 LANDFILL GAS DATA FORM................................................................... 12 4.2 METHANE MONITORING REPORTS ....................................................... 12 4.3 PERMANENT RECORD KEEPING ............................................................ 12 5.0 CONTINGENCY PLAN ......................................................................................... 13 5.1 IMMEDIATE ACTION................................................................................. 13 5.2 REMEDIATION PLAN ................................................................................ 14 5.3 REPORTING AND DOCUMENTATION ................................................... 14 6.0 REFERENCES ......................................................................................................... 15 Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 1 1.0 BACKGROUND The objective of the Methane Monitoring Plan is to provide a monitoring system to effectively detect a release of methane to the unsaturated zone of the underlying soils above the groundwater. The monitoring of methane along compliance boundaries (i.e., property boundary) to demonstrate regulatory compliance is required by Title 15A North Carolina Administrative Code Subchapter 13B Section .1626(4)(a)(ii) and .1626(4)(b) [15A NCAC 13B.1626(4)(a)(ii) and .1626(4)(b)]. Cleveland County (County) had operated an unlined sanitary landfill located in the eastern part of the county, approximately six miles northeast of Shelby, North Carolina. This unlined former sanitary landfill is known as the West Site. The West Site has three areas, A, B and C, which have been landfilled by Cleveland County and no longer receive municipal waste as of January 1, 1998. The County completed the construction of a new lined (Subtitle D) landfill unit on the East Site, which became operational in July 1998 (Figure 1). Long Creek is located at the downgradient toe of the West Site. Similarly, Buffalo Creek is located along the downgradient toe of the East Site. Both the West Site and the East Site are also separated by Long Creek. In 2009 the construction of the new landfill, known as the Self-McNeilly Site, was completed (see Figure 1). The disposal of municipal solid waste at the Self-McNeilly Site began in September 2009. The disposal of municipal solid waste at the East Site was discontinued at the end of 2009. Therefore the municipal solid waste within Cleveland County is now disposed at the Self-McNeilly Site. The Self-McNeilly Site is separated from the East Site by Buffalo Creek. 1.1 LANDFILL SITES 1.1.1 West Site All of the closed landfill cells at the West Site are located west of Long Creek. One of these cells currently receives construction and demolition waste (C&D) on top of the closed municipal waste cell. These landfill cells are shown on Figures 1 and 2. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 2 1.1.2 East Site The West Site and East Site are separated by Long Creek. The disposal of solid waste at the East Site was completed in 2009 as this site reached design capacity. This cell subsequently received a final cover in 2010. 1.1.3 Self-McNeilly Site The Self-McNeilly Site is located east from the West and East Sites (see Figure 1). The East Site is separated from the Self-McNeilly Site by Buffalo Creek. The disposal of municipal solid waste at the Self McNeilly Site began in the Fall of 2009. The first cell at this site is known as Phase I. 1.2 SITE GEOLOGY AND HYDROGEOLOGY The locations of the multiple landfill cells (closed and open) require a methane monitoring system capable of encompassing all of these cells around the methane compliance boundary, which is the property boundary for these sites. The migration of methane is through diffusion and pressure gradient within the unsaturated zone above the water table. This migration is restricted by perennial streams, such as Long and Buffalo Creeks. 1.2.1 Regional Geology The landfill is located within the Piedmont Physiographic Province (Piedmont), an area underlain by ancient igneous and metamorphic rocks. These rocks commonly have a mantle of residual soil overlying the bedrock (LeGrand, 1988). This province is primarily underlain by several geologic zones or belts of plutonic rocks and low-grade to high-grade metamorphic rocks. Geologists have subdivided the Piedmont into five parallel geologic belts from east to Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 3 west: Carolina Slate, Charlotte, King’s Mountain, Inner Piedmont, and Blue Ridge. The site is located within the Inner Piedmont. Rock units in the landfill vicinity are indicated on published geologic maps to consist generally of mica schist and mica gneiss with subordinate quartzite, amphibolite and pegmatite. The Inner Piedmont Belt has been highly deformed with multiple episodes of folding, thrust and normal faulting, fracturing and diabase dike emplacement. Geologic mapping of the site area was done by Griffitts (1958) and published for an area just west of the site by Overstreet et al., (1963). Recent compilations by Brown and Parker (1985) and by Goldsmith et al., (1988) indicate the site area to be underlain by biotite gneiss (and schist) locally interlayered with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Metamorphic and deformational events in the Inner Piedmont resulted in extensive folding and faulting of the rock units. Several antiformal and synformal structures have been mapped in the site vicinity. The site is located about one mile to the east of the north-south trending axis of the Buffalo Creek Synform, as shown by Goldsmith et al., (1988). Goldsmith et al., (1988) indicated that the structure is overturned, with foliation of low dip to the east. Overstreet et al., (1963) had shown the structure to be an upright syncline. The virgin soils encountered in this area are the residual product of in-place chemical weathering of rock, similar to the rock presently underlying the site. In areas not altered by erosion or disturbed by the activities of man, the typical residual soil profile consists of clayey soils near the surface, where soil weathering is more advanced, underlain by sandy silts and silty sands. A transitional zone is normally found overlying the parent bedrock. The uppermost soils within the flood plains of streams often are alluvial (water-deposited) materials. 1.2.2 Site Geology Based on investigative activities conducted in the area south of the West Site, the primary geologic characterization of the underlying bedrock performed for this Site was conducted in the area south of the West Site. These geologic characterization activities included geophysical logs in the former Coal Yard water supply well (Law, 2002); boring logs from the pilot test for the Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 4 proposed remedial technology conducted south of the West Site (Shield, 2010); and, boring logs for deep rock proposed recovery wells along Airport Road (Shield, 2012). Two types of fracture zones were identified in the geophysical logs. The first type of fracture zone is the apparently discrete or singular open fracture, exhibiting a definitive strike and dip. The second type of fracture zone consists of non-discrete openings in the near-hole formation. Such openings may be due to high porosity zones or multiplicity of intersecting fractures. However this second type of fracture zone did not provide any strike nor dip estimates. Only the first type of fracture zones could be used to provide estimates for the strike and dip angles. Water-producing fracture zones are a subset of all fracture zones intersected by the borehole. The fracture pattern observed from the acoustic televiewer (ATV) log indicates that fracturing, within the open borehole of the Coal Yard water supply well, declines with depth below ground surface. This pattern of decreasing fracturing with increasing depth was previously observed from rock cores collected during the installation of several of the monitoring wells (MW-5 through MW-8) at the West Site (Law Environmental, 1993). The Rock Quality Designations (RQDs) for these four cores exhibited a consistent trend of increasing RQD percentages with increasing depth below ground surface. In addition to the oriented ATV geophysical logging in the Coal Yard water supply well, analyses of lineament orientation from topographic maps have been performed. In the lineament orientation analysis, slight grouping (elevated numbers or sets) of the fractures within orientation ranges roughly to the northeast/southwest and west-northwest/east-southeast directions are apparent. An acute angle between fracture sets usually indicates the directions of stress application; thus, the groupings suggest a dominant stress application in the east-west direction. Because this east-west stress orientation corresponds with the local north-south lithologic contact orientation (i.e., contact of rock bodies is usually perpendicular to stress application), the groupings provide a certain degree of data validation, in that the data reduction of fracture set orientation from the topography agrees with the regional geologic framework. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 5 Thus the bedrock underlying the site is a fractured rock with declining fracture density at increasing depths and relatively variable fracture orientations. The bedrock encountered at Wells RW-1 and RW-3 consisted of biotitic-micaeous-quartzitic Schist grading into and out of Gneissic facies, whereas the bedrock for the middle well (RW-2) was dominantly a Gneissic facies. This latter bedrock is typically what has been found at this Site in the previous bedrock wells (e.g., MW-4A, MW-5A, MW-26 well cluster and IW-1). These site-specific findings corroborate the regional geology for the area. 1.2.3 Site Hydrogeology The design bases for a methane monitoring plan for these three landfill sites is based on the conceptual understanding of the hydrogeologic system underlying the area based upon published sources for both the region and the data collected for the Site. Depth to groundwater measurements from the semi-annual sampling conducted for the past 15 years have exhibited similar potentiometric elevations across the Site. The most recent potentiometric maps for the site are shown on Figures 2 and 3. The direction of groundwater flow across the site is generally from the elevated topographic ridges toward the drainage features and creeks (i.e., Long and Buffalo Creeks) that are evident across the Site. The topography varies across the site from topographic elevations of about 920 feet above North American Vertical Datum (NAVD) down to 760-feet above NAVD near the perennial streams that are located at the Site. The methane monitoring probes should be installed just above the water table at the site. Therefore, two characteristics of groundwater elevations at the site are important for the installation of the methane probes: the depth of groundwater; and, the variation of groundwater from season to season. Generally, the annual cycle of the groundwater elevations vary less in those wells in close proximity to streams compared to wells located on topographic uplands. Groundwater elevation data gathered at this Site since 1994 does bear out this generalization. These data were used to install the methane probes, so that the probes did not intersect the water table. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 6 Together the groundwater elevation data measured at the monitoring wells provided guidance for the design of the methane probes at the Site. The maximum depths for the methane probes at the site were retained above the water table as much as possible during the installations. 1.3 REGULATORY LIMITS The regulatory limits for this site are twofold as follows: 1. The concentration of methane gas will not exceed the lower explosive limit (LEL) for methane (i.e., 5% of methane concentration in air) at the facility property boundary; and 2. The concentration of methane gas generated by the facility will not exceed 25% of the LEL for methane (i.e., 1.25% of methane concentration in air) in facility structures (excluding methane gas control or recovery system). Together these two regulatory criteria should be met at the site. These regulatory criteria can be found within the regulations as per 15A NCAC 13B.1626(4)(a)(i) and .1626(4)(a)(ii). Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 7 2.0 LANDFILL GAS MONITORING 2.1 EXISTING MONITORING LOCATIONS An existing methane monitoring network for the Cleveland County Landfill has been used at this site since the 1990s. Over the years various methane probes have been added due to property acquisitions and new landfill cells. The current methane monitoring network is outlined below and is summarized in Table 1. This methane monitoring system is focused on the property boundary (i.e., the compliance boundary) around the site, particularly where the property is closest to the landfill cells. 2.1.1 West Site The Methane Monitoring Program for the former landfill (West Site) has included the monitoring of the permanent property boundary methane monitoring probes around the site. However, as a result of various property acquisitions that were completed in an effort to create a buffer around the West Site, new methane monitoring probes were necessarily installed either along or near the new property boundary over the years as outlined below. Some portions of the new property boundary consisted of a stream. After several property acquisitions, new methane monitoring probes were installed (MP-12 through MP-14). Also, a series of methane monitoring probes were installed along Airport Road (EP-7S/D through EP-11S/D). Additionally, in some areas of the property boundary, select ground-water quality monitoring wells (MW-1, MW-2, MW-19, LF-1, LF-2, LF-3, and LF-4) became available for monitoring methane along the west property boundary of the West Site to demonstrate regulatory compliance along the property boundary as required by 15A NCAC 13B.1626(4)(a)(ii) and .1626(4)(b). The use of monitoring wells for methane does require a confirmation that the water surface is below the top of the well screen. For public health and safety Cleveland County personnel continue to monitor landfill facility structures and off-site structures on a weekly basis. The locations of the methane monitoring probes are shown on the attached Figures 2 and 3. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 8 In some areas the property boundary is a perennial stream and no new methane probes were installed along that segment of the property boundary. Together both these new and some of the old methane monitoring probes, and the selected monitoring wells (i.e., when the top of the well screen is above the water table), comprise the current property boundary methane monitoring for the West Site. The methane probes located either along or near the property boundary starting at the southeast area of the West Site and going clockwise around the West Site are currently as follows: EP-11S/D, MP-14, LF-4, MW-19, MP-12, and MP-13 (see Table 1). 2.1.2 East Site The initial Methane Monitoring Program for the East Site consisted of fourteen additional methane monitoring probes (P-1 through P-14), which were installed on October 28, 1999 and November 9, 1999. However, the nearest property boundary around the East Site is Buffalo Creek, except for the area located northeast from the East Site (see Figure 2). Most of these methane probes are located along a strip of land between the toe of the closed landfill berm and Long and Buffalo Creeks. Due to the variable presence, and in some probes the continued presence of methane in these methane monitoring probes since about 2004, two new methane monitoring probes (i.e., P-15 and P-16: see Table 1) were installed along the property boundary northeast from the East Site in November 2008. This property boundary is the closest property boundary to the East Site that is both on land and not separated by water from the East Site Landfill. 2.1.3 Self-McNeilly Site The Methane Monitoring Program for the Self-McNeilly Site consists of seven methane monitoring probes (MP-101 through MP-107) which were installed on October 13, 2008 by Municipal Engineering Services, Inc. The methane monitoring probe depths ranged from 6.4 to 18.1 feet below ground surface (see Table 1). The property boundary around the Self-McNeilly Site that is closest to the currently active cell is along Buffalo Creek to the west. The closest land-based property boundary to the currently active cell is located 830 feet beyond Methane Probe MP-102 to the southeast (along the Seaboard Coast Line railroad track). Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 9 2.2 STRUCTURE MONITORING For public health and safety Cleveland County personnel continue on a weekly basis to monitor landfill facility structures and off-site structures. These structures include the on-site buildings such as the maintenance shop, scale house, and the animal shelter. Additionally, the off-site buildings used at the Coal Yard facility located at south of Airport Road are also monitored on a weekly basis. In addition to this regular monitoring program a total of 12 permanent methane monitors have been installed at the animal shelter. These methane monitors are capable of providing an alarm whenever methane is detected. 2.3 MONITORING FREQUENCY The methane monitoring frequency is quarterly for the methane probes located around the site. These methane data are reported to the SWS on a quarterly basis. The buildings and structures are monitored on a weekly basis and these data are retained at the site. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 10 3.0 LANDFILL GAS MONITORING PROCEDURES Section 3.1 provides details of the equipment used for the monitoring of the methane around the Cleveland County Landfill sites. The procedures used to perform this methane gas monitoring are described in Section 3.2. 3.1 DETECTION EQUIPMENT The methane gas monitoring at the Cleveland County Landfill sites is performed on a quarterly basis using a Landtec gas analyzer and extraction monitoring instrument - GEM2000. This instrument is rented from a local provider that also provides the semi-annual factory calibration records. A copy of these records is provided with each quarterly methane monitoring report. Additionally, the field calibration is conducted within a controlled environment. This particular calibration is initiated with a zeroing of the instrumentation data files. Each of the methane, oxygen, and carbon dioxide alarms are subsequently checked as being functional. The pump flow rate is measured and recorded and the instrument vacuum is tested to 70 inches of water. The final step of the instrument calibration for the monitoring event is the gas calibration using the 35/50 gas canisters (i.e., 35% carbon dioxide and 50% methane). Each of these two calibrations are required to be within + 3% of the calibration gas concentration. The calibration for the oxygen is conducted using 4% oxygen and is required to be within + 1% of the calibration gas concentration. 3.2 LANDFILL GAS MONITORING PROCEDURE The landfill gas monitoring procedures used to operate the Landtec GEM2000 are as follows:  Following the instrument calibration, make sure the static pressure shows a reading of zero on the instrument prior to taking the first sampling;  Purge the sample tube for at least one minute prior to taking the gas reading. Connect the sample tube to the methane monitoring probe;  Open the valve and record the initial gas reading and then the stabilized reading. A stabilized reading does not vary by more than 0.5% by volume on the instrument’s scale; Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 11  Record the stabilized reading including the oxygen and carbon dioxide concentrations and the barometric pressure;  Turn off the gas entering the instrument and disconnect the tubing from the methane probe fitting; These steps are repeated from probe to probe, until all of the methane monitoring probes have been measured around each of the sites. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 12 4.0 RECORD KEEPING AND REPORTING Section 4 provides details of the record keeping and reporting for the methane monitoring at the Cleveland County Landfill. 4.1 LANDFILL GAS DATA FORM The data form provided by the SWS is used for recording methane gas monitoring data recorded at the Cleveland County Landfill sites. A supplement form is also used for additional methane monitoring probes beyond the ten provided for on the SWS data form. This supplemental form also includes the facility identification, the permit number for the facility, date of the data collection, and the same certification statement as included on the SWS data form, with a signature block for the person recording the data. With these data on the supplemental form, this supplemental form can be appropriately linked directly to the SWS data form with the appropriate instrument and calibration information. 4.2 METHANE MONITORING REPORTS The methane monitoring data collected at the landfill are compiled into a quarterly report and submitted to SWS. This report includes a copy of the SWS data form with any supplemental data forms providing all of the data collected during the monitoring event. Additionally, a copy of the factory calibration records are provided with a copy of the calibration records for each field monitoring event. 4.3 PERMANENT RECORD KEEPING The SWS data forms and the quarterly methane monitoring report are retained at the Cleveland County Landfill for inspection. These documents are a part of the permanent record for the landfill. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 13 5.0 CONTINGENCY PLAN In the event the methane gas is recorded above the LEL at the property boundary a contingency plan is required for the Site. The contingency plan includes the specific steps that should be implemented to protect human health and the environment. Components of the contingency plan consist of immediate action; reporting and documentation; and, remediation plan. 5.1 IMMEDIATE ACTION The following actions comprise an immediate response to the finding of methane gas in a property boundary probe exceeding the LEL:  Confirm the instrument calibration and check the presence of methane gas in the methane probe with a second reading, if the methane persists use another calibrated methane monitoring probe for acquiring a confirmatory methane reading;  Check methane gas in structures near the methane probe in which the methane exceedance was identified;  If the methane gas within the structure exceeds the 25% of the LEL, the structure will be evacuated following communication with County Agencies and the SWS site manager;  Check other methane probes in the area and also investigate the possible source and avenue of transport of the methane gas to the area of concern. Such an investigation may consist of a soil gas survey in the area, or bar hole probes to check for methane, or other methane monitoring methodology acceptable to all parties (i.e., Cleveland County, SWS, and adjacent property owners);  As appropriate draft a plan of remedial action and begin remedy procedures to control methane concentrations within the building(s) in which the methane was found to exceed 25% of the LEL. These immediate actions provide a basis for moving forward in a relatively rapid manner upon the identification of a methane accumulation in structures adjacent to the landfill property. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 14 5.2 REMEDIATION PLAN In the event that the prolonged methane gas concentrations persist and as identified during the implementation of the Immediate Action Plan as described in Section 5.1, a Remediation Plan shall be prepared. This plan will describe the nature of the problem, the extent of the problem, and the proposed remedial action to be implemented in the field to alleviate the extent of the methane in the area of the recorded methane exceedances of the LEL. 5.3 REPORTING AND DOCUMENTATION Following the Immediate Action Plan provided in Section 5.1, and within seven days, the County must place the methane concentrations and a description of executed actions to protect human health in the operating record at the Cleveland County Landfill office. Within sixty (60) days a remediation plan describing nature of the problem, extent of the problem, and the proposed remedy shall be implemented and a copy of the Remediation Plan will be placed in the operating record. Cleveland County Landfill February 7, 2014 Methane Monitoring Plan DWM Permit #23-01 Shield Project 1040167 Page 15 6.0 REFERENCES Brown and Parker, 1985; Geologic Map of North Carolina, North Carolina Geological Survey, Division of Land Resources, Raleigh, North Carolina. Goldsmith, Richard; Daniel J. Milton and J. Wright Horton, Jr., 1988; Geologic Map of the Charlotte 1o x 2o Quadrangle, North Carolina and South Carolina, United States Geological Survey, Miscellaneous Investigations Series MAP I-125-E. Griffitts, Wallace R., 1958; Pegmatite Geology of the Shelby District, North Carolina. United States Geological Survey, Open-File Report. Law Environmental, Inc., 1993; Report of Laboratory Chemical Testing, Ground-water Sampling, East Site, Cleveland County Landfill. Charlotte, North Carolina. Law Engineering and Environmental Services, Inc., 2002; Hydrogeological Conceptual Model, Cleveland County Landfill- West Site, Charlotte, North Carolina. LeGrand, Harry E., 1988; Region 21, Piedmont and Blue Ridge, in Back, W., Rosenhein, J.S. and P.R. Seaber, (Editors), Hydrogeology – The Geology of North America, Volume O-2, The Geological Society of America, Boulder, Colorado. Overstreet, W.C., R.G. Yates, and W.R. Griffitts, 1963; Geology of the Shelby Quadrangle, North Carolina, United States Geological Survey, Miscellaneous Geologic Investigation Map I-384, Raleigh, North Carolina. Shield Engineering, Inc., 2010; Pilot Injection Test – Remediation Report, Cleveland County Landfill- West Site, Charlotte, North Carolina. Shield Engineering, Inc., 2012; Hydraulic Control Test Report, Cleveland County Landfill- West Site, Charlotte, North Carolina. H:\Projects\2004\1040167 Cleveland County - General\Permits\Methane Monitoring Plan.doc