WORK PLANS_FILE 2 - Laserfiche WebLink

Home Browse Search

C A M B R I A Utility Clearance: Proposed drilling locations will be marked and their locations cleared through Underground Service Alert (USA) prior to drilling. Site Investigation: Two exploratory soil borings (SB-5 and SB-6) and four groundwater monitoring wells (MW-8 through MW-11) are proposed at the locations shown on Figure 2. Borings SB-5 and SB-6 will be drilled adjacent to the former UST complex and the northern dispenser island, respectively. These borings will be drilled to assess the vertical extent of hydrocarbons in soil beneath site. Boring SB-5 is located hear the former UST complex © because the former USTs are the likely source of hydrocarbons detected in groundwater. The location of boring SB-6 was selected based on elevated hydrocarbon levels detected in soil samples from boring SB-4, which was drilled near the northern dispenser island. This is the closest we will be able to drill to the original location of SB-4 with the drilling equipment we will be using for this work. he total depth of the borings will be determined in the field based on field observations such as soil odor, soil staining, and photo-ionization detector (PID) measurements. When these • field observations indicate hydrocarbons have not been detected for a minimum of ten feet, the boozing will be terminated. The minimum depth of these borings will be 70 fbg. This is basedNhistorical water level data which indicates groundwater has been as deep as 65 to 70 fbg in this area of Stockton. The proposed monitoring wells are located downgradient of the site and downgradient of existing monitoring wells, which contain hydrocarbons (Figure 2). These wells will be constructed to monitoring shallow groundwater. The soil borings will be drilled with Cone Penetrometer Testing (CPT) equipment. The monitoring wells will be drilled using hollow-stem auger equipment. A Cambria geologist will supervise the drilling and describe encountered soils using the Unified Soil Classification System and Munsell Soil Color Charts. Soil samples will be collected at five-foot intervals for lithologic description and possible chemical analysis. Soil samples will be screened in the field at five-foot intervals for organic vapors with a PID. PID readings will be recorded on the boring log for each boring. Soil samples will be retained in sample tubes and will be covered on both ends with Teflon sheets and plastic end caps. Soil samples will be labeled, entered onto a chain-of-custody • record and placed into a cooler with ice for transport to a State of California certified laboratory for analysis. 0854 4