WORK PLANS - Laserfiche WebLink

Home Browse Search

i ' PROPOSED INVESTIGATION Apex proposes to drill six soil borings to approximately 30 feet below grade (bg) and complete -, -them as-2-inch-diameter groundwater monitoring wells MW-1 through:MW-6 (Figure 3). A11 fieldwork will be conducted.in accordance_with the Apex Standard Operating Procedures (SOP). included as'Attachment 1. Previous subsurface sampling indicates groundwater ranges from approximately fifteen to twenty feet bg at the site. Based on this information, the six proposed.wells will be drilled to a total depth of 30 feet bg and screened from 10'to 30 feet bg. Groundwater gradient is towards the north, northeast according to the County. The wells will be installed with 0.02-inch perforated casing. The filter pack will be placed from 2 feet above the screen interval to total depth. The bentonite seal will be placed frorn 2 to 4 feet above the filter pack and.a bentonite/cement slurry will be placed from near surface to 4-feet above the filter pack. The wells will be secured with a locking,_water-tight cap=and an.8-inch- ._ diameter traAc�rated wellhead vault (Figure 4). Proposed wells MW-1 through MW-3 will be placed in the area of the former gasoline USTs on the western portion of the site (Figure 3). Well N4W.-1 will be used to.define the upgradient extent of petroleum-impacted groundwater while proposed wells MW-2 and MW-3 will be used to define the lateral and downgradient extent of petroleum-impacted groundwater. Proposed wells MW-4 through MW-6 will be placed in the area of the former diesel USTs on the western portion of the site (Figure 3). Well MW-4 will be used to define the upgradient extent of petroleum-impacted groundwater while proposed wells MW-5 and MW-6 will be used to define the lateral and downgradient extent of petroleum-impacted groundwater. The six wells should provide sufficient data to accurately document groundwater levels, gradient and possibly define the extent of petroleum impacted groundwater. Prior to drilling, the underground utility notification network, USA, will be contacted for identification of buried utilities at or entering the project site from the public right-of way. As a further precaution against drilling into or through potential buried obstructions, the first five feet of each boring will be augured by hand. Following installation, the top-of-causing elevation of each new well will be surveyed. I a I ' 1 - - Y