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1111195 09 10 39 WFAA Laptop FAX Miliam F Mo0ennay RG FkFA Pa"3 at 5 r - W Robert Huntley 1 l January 1995 Page 2 November 1994 collection for TPH as motor oil, however the only sample to record a detection was the sample from the 46 5 foot below ground surface(BGS)level Rick Keep, the field geologist present at both installation periods indicated that during the first installation attempt, the hydraulic pump, mounted behind the retractable drilling coast, failed and attempts to effect field repairs by the drilling crew caused small releases of hydraulic fluid to escape in the vicinity of the open boring It is considered possible, though somewhat unlikely that the TPHmo detected in SN4W-46 5 came from this release This opinion is derived from the facts • drilling was tmu nated on 16 November 1994 at the 30'BGS level, • at least three other soil samples were taken above the 46 5' BGS level prior to collection of the sample from that depth horizon-all of winch were not found to contain detectable hydrocarbons in the range detected in SMW-46 5, • the sample from the 46 5' BGS level was collected about two weeks after the release of hydraulic fluid was known to have occurred, so the only realistic avenue for hydraulic oil contamination hes in contact at the ground surface with some source, • it is not known at present if hydraulic oil of the type used by Frontier dnlhng would show up in the TPHmo analysis The potential therefore exists that either the TPHmo detection is an anomaly related to some avenue of unpact with hydraulic oil or that the analysis indicates that some substance detected in the range of TPHmo exists at the soilhvater interface in NIW4 MW4 was developed after installation was complete On 6 December 1994, RFA purged the well and collected a groundwater sample for laboratory analysis The sample was subjected to analysis for organic lead in water, TPHd, and TPHg1BTEX. All analyses were reported to be below their respective method reporticig limas In a sense, the groundwater analyses came as somewhat of a surprise Mr Keep had reported olfactory detection of chemical odors that he could not readily identify in both the development water and in the purge water withdrawn from MW4 on two separate occasions After receipt of the groundwater analyses, telephone discussions were held with Mr Harlin Knoll from the San Joaquin County Public Health System. In these discussions, it became apparent that Mr Knoll, who had been present for various aspects of MW4's installation and sampling, had also detected the odors described by Mr Keep Mr Knoll suggested in this conversation that the well should be re-sampled as soon as possible in order to attempt confirmation of the initial results In the, discussions it was indicated that a split of the sample obtained during the re-sampling would be sent to the county's contract analytical laboratory for duphcate analyses