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EPA’s Emergency Response Branch was requested to assist the IEPA in March of 2007 at the Wayne Township Ground Water site in Northern DuPage County, Illinois. U.S. EPA upon reviewing available data and well logs from the Mallard Lake landfill discovered a boring conducted by BFI contractor Hearst and Assoc in April of 2006 with methane levels of 17.9% concentration within 50 feet of a residential neighborhood on the West perimeter of the landfill. U.S. EPA requested the operator of the landfill, BFI, and owner of the landfill, DuPage Forest District, to conduct an investigation outside the West boundary, South Boundary and on the Right-of Way to determine the extent of the gas migration off site. This landfill gas has historically contained high levels of Volatile Organic Compounds including vinyl chloride which was reported by the landfill operator to lead to ground water contamination exceeding the Maximum Concentration Limit (MCL) for vinyl chloride at the Western perimeter of the landfill.
During the first phase of the investigation conducted November 6-10, high levels of methane exceeding 75% in concentration were detected in temporary monitoring wells at locations within 30-50 feet from residential homes. The permeable zone containing this methane is 40-45 beneath the ground surface. BFI consultants STS, began installation of shallow monitoring wells on November 31, 2007.
During this reporting period, WESTON provided oversight of 13 Cone penetrometer (CPT) probes (CP26, 27, 28, 30, 31, 32, 34, 35, 36, 37, 38 and RW-17) installations. Refer to Table 2 and Figure 2, for information on CPT Installations. CP26, 27, 28, 20, 27, and 38 had methane detections between 9.4 and 67% with a push depth between 47 and 62 feet. At these locations the utilities were cleared by the Hanover Park Public Works Department vacuum truck. The depth of up to 6 feet was vacuum extracted to check for presence of subsurface utility at each location. Prior to starting the CPT installation each vacuum location was filled with sand. On January 5, 2008, during the initial push at CP28, the drill crew encountered what appeared to be a void about 7-8 feet bgs. The rig was re-positioned approximately 5 feet west of the original push location. STS along with the CPT crew and WESTON will continue CPT probe installations and monitoring in the subdivisions west of County Farm Road during next week (Refer to Figure 2, for CPT locations). These probe installations will provide additional information to further assess the westward extent of methane landfill gas migration. Based on Figure 2, the westward investigation area is bound by Green Bridge Lane In addition, STS has proposed a deep well installation at CP12 (See Figure 2).
Residential screening continued during this reporting period with a total of seven homes screened and no explosive gases were detected (See Figure 1). Two of the seven homes screened were located in the subdivision west of County Farm Road. In addition, explosive gas detectors were installed at six of the seven homes screened. The detectors were installed after obtaining consent from the respective residents. The homes were located along Zeppelin and Bell Drive, Howe, Eastman and McCormick Lane. These detectors are similar in size and operation to a smoke detector, and can detect the presence of methane, propane and other explosive gases. The detectors sound an audible alarm when the gases reach a concentration that is 25 % LEL. All residents are given written and verbal instructions on what to do when the alarm sounds. BFI has prepared a contingency plan with emergency contact information if an alarm sounds. In the contingency plan, residents are advised to call 911 which will notify the Hanover Park Fire Department.
To date, the U.S. EPA, STS (BFI contractors) and WESTON have screened 132 homes, installed 110 explosive gas detectors and visited a total of 207 homes (See Figure 1-Residential Screening Summary). BFI’s public relations consultants, Reputation Partners continue to schedule the residential screening and gas meter installations with field support by STS and WESTON personnel.
No slam-bar sampling was conducted during this reporting period, but STS continues to offer the investigation to residents during residential screening and gas meter installation.
U.S. EPA is meeting weekly on Monday’s at 2:00 PM to inform and update pertinent parties and agencies involved. The next meeting will be held January 14, 2008
U.S. EPA along with state and local representatives will hold a public meeting on Thursday, January 17, 2008 at the Horizon Elementary School at 1701 Greenbrook Boulevard, Hanover Park, Illinois to discuss the Administrative Settlement with the Mallard Lake Landfill site (See Mallard Lake AOC Advertisement). The meeting will address the landfill gas investigation with local residents.
BFI and STS plan to conduct a pump test at TW-1 which was installed along the north side of Schick Road (just south of the landfill) on December 9, 2007. BFI and STS also plan to conduct Shut-Ins Test.
Investigative and remedial work plans submitted by BFI and STS to investigate the gas migration and analyze the landfill gas and ground water are reviewed by U.S. EPA and their consultants Weston Solutions, Inc.
BFI public relations consultants Reputation Partners along with STS continue to distribute literature (door hangers) regarding residential screening and gas meter installation to local residents residing in the investigation area.
U.S. EPA entered into an Administrative Order of Consent (AOC) with BFI and the DuPage Forest District regarding methane gas investigation. The AOC requires BFI and the DuPage Forest District to complete the emergency assessment and investigation work to determine the extent of the methane gas leakage from the landfill, and to complete long-term measures to control the off-site migration of landfill gases.
• BFI and STS will continue screening homes and installing explosive gas meters based on appointments scheduled by Reputation Partners public relations
• BFI and STS will continue methane gas migration investigation using the CPT rig and conducting weekly methane gas monitoring of existing and newly installed probes;
• BFI and STS will conduct soil gas sampling at designated shallow gas probe locations;
• BFI and STS will install and sample shallow soil gas near residential homes (based on access); and
• BFI and STS will install and sample sub-slab sampling ports (based on access); and
• BFI and STS, will prepare a plan to improve and expand the methane recovery system and to address methane that has migrated off the property.
• STS plans to conduct pump test and Shut-Ins Test.
• U.S.EPA and WESTON will continue to provide oversight of the work performed by BFI and STS.
• Obtaining access to private homes to install shallow soil gas probes and sub-slab ports has been problematic; and
• Clearing of utilities along the right of ways in ample time for CPT installations.
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