Laserfiche WebLink
Groundwater Monitoring <br /> Well Installation and <br /> ARCADIS Sampling Work Plan <br /> PG&E McDonald Island <br /> Compressor Station <br /> 3. Proposed Activities <br /> ARCADIS proposes to install three monitoring wells at the site. One monitoring well will <br /> be located upgradient of the excavation area, and two monitoring wells will be located <br /> downgradient of the excavation area(Figure 4).The assumed groundwater flow <br /> direction in the area is to the northwest(MSE Group 2009). The purpose of the <br /> upgradient monitoring well is to assess groundwater quality at the upgradient edge of <br /> the site,and the purpose of the downgradient monitoring wells is to evaluate whether <br /> TPH-d concentrations identified near the excavation area are moving off-site. The new <br /> wells will also provide a more accurate representation of groundwater flow direction at <br /> the site. <br /> A detailed description of the sampling activities is provided below, and the proposed <br /> well locations are shown on Figure 4. <br /> 3.1 Pre-Field Activities <br /> Prior to initiating field activities, the site-specific health and safety plan will be updated <br /> in accordance with state and federal requirements, and monitoring well installation <br /> permits will be obtained from San Joaquin County Environmental Health Department. <br /> An Underground Service Alert ticket will be issued for the site, and a private third-party <br /> utility locator will screen the proposed well locations to identify potential conflicts with <br /> underground utilities.Additionally, per PG&E requirements, all sampling activities will <br /> be conducted in the presence of a qualified PG&E electrical observer. <br /> 3.2 Monitoring Well Installations <br /> To minimize the potential for encountering subsurface utilities,the well locations will be <br /> cleared to a minimum depth of 5 feet bgs with a hand auger or air knife/vacuum truck <br /> equipment prior to drilling. Once cleared,the boring will be advanced using direct-push <br /> probing equipment to an approximate total depth of 16 feet bgs by a C-57 licensed <br /> drilling contractor. The exact depth of the well will be identified by the depth at which <br /> groundwater is encountered. Soil samples will be collected continuously in 4-foot long <br /> acetate liners, logged for stratigraphic characteristics,and field screened for the <br /> presence of volatile organic carbons(VOCs)using a photoionization detector(PID). <br /> After reaching total depth of the boring,the direct-push equipment will be removed <br /> from the borehole and the drill rig will be converted to hollow-stem auger drilling. Each <br /> Mcdonald Island Addtl MW Installation Work Plan.Doc. 5 <br />