During this reporting period, Weston and US EPA provided oversight on various corrective action procedures (installation of large diameter wells, radius of influence testing). STS submitted the off-site nature and extent of contamination report, Landfill Gas Extraction System Operating Data and Blower Evaluation Report. U.S. EPA is currently reviewing these reports.
STS conducted a sub-slab sampling at one private residential home. The results shows presence of low levels of VOCs well below the screening levels.
BFI and their public relations contractors Reputation Partners, Inc. have scaled back residential screening scheduling following slow to no response during repetitive efforts to contact residents within the investigation area. During this reporting period, four homes were screened and had explosive gas meters installed (at the discretion of the residents). To date, 243 homes have been screened, 209 explosive gas detectors installed and 313 total homes have been visited. Refer to Figure 1-Residential Screening Summary_031408 and Table 1 – Residential Screening Summary_031408).
Residential slam-bar sampling was deferred due to weather restrictions. STS has access to over 40 properties to conduct the sampling as a result of residential screening and gas meter installation. However, instead of slam bar testing, sub-slab sampling will be performed at the homes (where access is available from owners of the residential properties) in close proximity of the site. In addition to this limited shallow monitoring probes will be installed on selected number of residential properties to check for landfill gas (methane and VOCs). During this reporting period replacement well was installed and sampled at monitoring well 12D.
BFI and STS are currently working on emergency corrective action measures to capture current and prevent future methane gas releases (Phase II). Testing such as radius of influence study, pump tests, and soil gas sampling have already begun to assess the efficiency of the current extraction system, to alleviate gas pressures and determine the most efficient correction action. In addition, four large diameter wells have been installed on the West and one large diameter well has been installed on the South Perimeter in an attempt to prevent the migration of landfill gas off-site. Need for additional wells will be evaluated based on the performance results of these wells. The large diameter wells have been connected to the existing gas collection system. Groundwater pumped to lower the water table is collected and discharged into a existing leachate header. During this reporting period landfill fire has been detected in the vicinity of extraction well EW-70. As a result of the subsurface landfill fire approximately 20 extraction wells have been taken offline. Landfill fire situation is being monitored by a GRS (BFI subcontractor) employee. The blower for the flare system needs to be repaired/replaced. BFI has ordered the blower and the lead time for the blower is at least 14 weeks. STS conducted soil gas sampling using summa canisters on February 22, 2008 at 17 various cone penetrometer and existing landfill gas monitoring probes (Refer to Table 2, Soil Gas Sampling Field Data). Each probe selected was based on elevated methane gas concentrations detected during initial CPT push or frequent monitoring. Each probe was purged for 2-5 minutes using the LandTech GEM-500 methane detector and sampled using a -30 Hg summa canister for up to one hour or until the pressure gauge indicated the canister was full. CP55 (an original sampling locations) did not detect any methane gas during purging and STS instead sampled CP47. The 17 probe samples, two duplicates and one ambient air were shipped to Con-Test Laboratories of East Longmeadow, MA for analysis of TO-15 VOCs and methane. Analytical results for this sampling have been received and are being reviewed by U.S. EPA.
STS also conducted groundwater sampling from March 6-12, 2008 at specific CPT monitoring probes to determine the extent of VOCs present in the landfill gas. Twenty-one monitoring probes (CP1, 2, 4, 12, 12D, 14, 18, 20S, 26, 28, 30I, 33S, 35, 38, 47, 55, RW-4, 5, 6, 8 and 26) were chosen for groundwater sampling based on previous methane gas monitoring concentrations. Refer to Figure 2 – Groundwater Sampling Locations. Of the 21 wells, only 18 (CP4, 12, 26, 2, 38, 35, 33S, 15, 19, 28, 30, 47, 55, RW-26, 4, 5, 6 and 8) were sampled due to inefficient amount of available water and/or dry wells. Dry wells were replaced with wells providing sufficient amount of water for sampling. STS purged each well with sufficient water column using bailers and measured water quality parameters including turbidity, pH, conductivity, temperature and oxidation reduction potential (ORP). WESTON provided oversight support during the sampling event and collected four split groundwater samples (at CP4, 26, 2 and RW-8). All groundwater samples collected will be analyzed for VOCs using EPA SW 846 Method 8260; analytical results for this sampling has been received and are being reviewed by the U.S. EPA.
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