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' The entire site area is 567 acres. Approximately 144 acres of this area comprises the existing Forward Landfill and 244 acres comprises the former Austin Road Landfill. The existing Forward Landfill acreage includes an 8 -acre hazardous waste cell known as Waste ' Management Unit (WMU) A. WMU A was closed in 1989 and is currently complying with post -closure monitoring requirements. The existing grade at the toe of slope is approximately 38 -feet above mean sea level (amsl) and according to the latest survey data, refuse has been documented at elevations ranging from approximately 25 -feet to 150 -feet amsl. 1.3 PROJECT OBJECTIVES ' The objective of this Work Plan is to design and implement a gas extraction system in an effort to prevent LFG from migrating beyond the Forward Landfill's western property boundary and bring the gas monitoring probes into compliance within regulatory limits. ' With a series of wells and probes installed along the perimeter, a "vacuum curtain" will prevent LFG from extending beyond the property line. 1 1.4 PROJECT APPROACH This Work Plan will be conducted in two phases. The initial phase will include the installation of 39 additional perimeter gas monitoring probes and 13 vertical gas extraction wells along the western boundary. A recent Authority to Construct with the San Joaquin Air Pollution Control District currently only allows for an additional 13 wells to be installed ' (95 total). As part of the second phase, Forward will permit additional LFG extraction wells and install the remainder of the wells as outlined in this Work Plan. The gas monitoring ' probes installed under the initial phase will define the extent of LFG migration and also prove that the LFG extraction wells are providing the required radius of influence necessary for "vacuum curtain" along the boundary. ' After probe monitoring has been completed, the data will be evaluated and a determination will be made regarding the need for, and location of, additional LFG ' extraction wells for the next phase. LFG extraction wells will be installed in all areas where LFG is detected in the perimeter probes above the regulatory limits. 2.0 EVALUATION OF THE EFFECTIVENESS Of THE EXISTING AND PROPOSED PERIMETER GAS EXTRACTION WELLS 1 2.1 INTRODUCTION ' BAS has conducted an evaluation of the effectiveness of thero osed LFG extraction wells p p ' to be installed on the western property boundary of Forward Landfill. The purpose of these wells is to ameliorate concerns that off-site migration of LFG may be occurring along this 2 Installation Work Plan to Remediate Landfill Gas Migration ' J:\Allied\Forward\Workplan\Forward Evaluation - rev4.doc:9/15/2004