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Ms. Connie Davis/Aggregate Industries - F S[reet Soil and Groundwater Abatement Re ort Project Number 1001018 ~'nRnGON ,1~ty s, 2001 Page 2 Based on information provided by Aggregate Industries, the volume of the diesel-fuel spill was estimated to be approximately 10,840 gallons and reportedly occurred over a relatively short period of time from mid-March to the end of April 2001. Upon excavation of the underground piping, it was discovered that the leak appeazed to have occurred from a faulty pipe fitting on the south side of the AST basin. Test pits were completed at the site on May 8, 2001 as a preliminary evaluation of the extent of contamination in preparation for abatement of the diesel-fuel spill. The spill area is located on the west side of the subject site. Future activities for the spill area include the mining of the gravel resources. The long-term planned usage for the site is an open pond at the spill area with residential development west and east of the spill area in accordance with the Reclamation and Use by Special Review permits issued by the Colorado Division of Minerals and Geology and Weld County, respectively. 2. SOIL ABATEMENT ACTIVITIES Soil abatement activities consisting of the excavation and re-use of contaminated soil in asphalt mix was performed at the site by Aggregate Industries personnel between May 8 and Ma}• 31, 2001. Approximately 2,000 cubic yards of contaminated soil was excavated from the spill area and stockpiled at the site for use in asphalt paving mix. The excavated ry material was processed on site using the crusher to segregate the coarse rocks from the fine 11 materials. The approximate extent of the abatement excavation which was completed at the site is shown on Figure 3 in Appendix A. The resultant abatement excavation was completed to a depl:h of approximately 13 to 15 feet below grade. Groundwater was encountered during the '} abatement activities at depths of approximately 11 to 12 feet below grade. Water and free- , pha:;e product were pumped from the abatement excavation for off-site disposal as described in Chapter 3 of this report. Thirteen (13) soil samples were collected during the abatement process. Eleven (11) soil samples were collected for assessment purposes to document the concentrations of petroleum hydrocarbons which were present near the edges and bottom of the abatement excavation while two (2) soil samples were collected to document the concentrations of petroleum hydrocarbons in soils excavated from the site. The soil samples were transported under standard Paragon chain-of-custody procedures to Technology Laboratory, Inc. (TLI) for benzene-toluene-ethylbenzene-xylenes (BTEX) and total extractable petroleum hydrocarbons (TEPH) analyses. Three (3) oT the soil samples were also analyzed for polynuclear aromatic hydrocarbons (PAHs). The soil sample results are discussed in Section ~+.I of this report.