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Mann,J. <br /> Page 2 <br /> bgs) in the eastern portion of the verti-cast area. PID readings are shown on the boring logs. The <br /> sample designations and their corresponding depths are summarized in Table 1. The 19 soil <br /> samples were sent to ALS Global Laboratories in Houston, Texas, for analysis for mineral oil by <br /> EPA Method SW8015M. The analytical laboratory report is attached as Attachment B <br /> Mineral oil concentrations in the 19 soil samples ranged from 20 milligrams per kilogram <br /> (mg/kg; SB 11 at 5 feet bgs)to 12,000 mg/kg(SB3 at 3 feet bgs). The bulk of the form oil residue <br /> is entrained in the soil in the central portion of the northeastern concrete pad as expected based <br /> on usage details provided by NOV Ameron personnel. The greatest volume of form oil is sorbed <br /> to the upper 3 feet of the soil column surrounding the verti-cast area. The soil analytical data are <br /> presented by sample location on Figure 3. <br /> CONCLUSIONS <br /> The additional evaluation of the initial assessment data collected in February 2014 confirmed <br /> that the potential impacts'were actually mineral oil, a non-regulated substance. The August 2014 <br /> environmental investigation of the verti-cast area has provided an assessment of the horizontal <br /> and vertical extent of the form oil residue in the native soil. Form oil residue is present <br /> throughout the soil surrounding and between the two concrete pads and has infiltrated the soil to <br /> a depth of 5 feet bgs. The greatest volume of form oil residue is contained within the upper 3 feet <br /> of the soil column. <br /> LTE recommends periodic removal of the form oil rebound material from the verti-cast area to <br /> prevent accumulation of excessive amounts of form oil residue in and around the area and the <br /> installation of a small curb around the concrete pads to prevent the material from dispersing <br /> during daily site activities. These recommendations are given for aesthetic and housekeeping <br /> reasons and not to maintain regulatory compliance. <br /> Thank you for giving LTE the opportunity to assist NOV with the evaluation of this facility. <br /> Please call me at 352-371-1770 or Ms. Karen Trantow Lim at 303-433-9788 if you have any <br /> questions or concerns. <br /> Sincerely, <br /> LT ENVIRONMENTAL, INC. <br /> Keith Pollman, P.G. Karen Trantow Lim, P.G. <br /> Senior Hydrogeologist Principal Geologist <br /> cc: Mr. Brian Ameen,NOV <br /> Attachments <br />