ARCHIVED REPORTS XR0012685 - Laserfiche WebLink

Home Browse Search

f November 18, 1991 MffffMA ~ ARCO Station No. 2130, Stockton, California casing with 01-inch-wide slots. Our previous Work Plan also includes the Site Safety Plan and Emergency Route to the Hospital, examples of the field boring logs, the Unified Soil Classification System,and Logs of Borings. We have included the following attachments to this addendum: a description of additional field methods, a schematic groundwater well design and a modified schematic vapor-recovery well design. We propose the foIIowing tasks to conduct the subsurface investigation: o Acquire a drilling permit from the SJCPHS-EHD. k o Contact Underground Service Alert and the SJCPHS-EHD at least 48 hours before drilling to delineate public utility lines at the site. o Drill three 10-inch-diameter soil borings to 10 feet below ground water (approximately 78 feet below grade) or 5 feet into the first aquitard, whichever is encountered first. The borings will be converted to 4-inch- diameter ground-water monitoring wells. The boring locations are shown on Plate 2. o Drill one 10-inch-diameter soil boring near boring B-1 to approximately 55 feet below grade and convert the boring to a 4-inch-diameter vapor-extraction well. The screen interval will be selected according to field evidence of hydrocarbons in soil from the boring. o Drill two 8-inch-diameter soil borings near the existing tank cavity but outside ` the area of the proposed tank cavity and four soil borings near the existing a product dispensers. The borings will be terminated at ground water or when t two consecutive soil samples with photoionization detector (PID) readings below 50 parts per million by volume (ppmv) are collected below 25 feet below grade. The borings will be converted to 4-inch-diameter vapor- extraction wells if warranted based on PID readings. The screen interval will be selected according to field evidence of hydrocarbons in soil from each boring- o Collect relatively undisturbed soil samples at 5-foot intervals or lithology changes from the ground surface to the total depth of each boring. Soil samples will be placed in iced storage and maintained at 4 degrees centigrade - --- for transport-to-the-analytical-laboratory. -- =34W 2 t .