ARCHIVED REPORTS XR0011054 - Laserfiche WebLink

Home Browse Search

.1 no gasoline hydrocarbons have migrated vertically through the soil beneath a depth of 30 at the property. " is not true. As shown above, TFH-G was detected in 3 of the soil borings at 30 , 35 & 40 ' bgl . It is true that gasoline was not measured in any of the other borings, but it was present below 350 ' . The statement made in paragraph I on page 21 -. . "gasoline hydrocarbons detected in the groundwater are not a result of release from the gasoline tank at Morita Phos. , but is a result of migration from an offsite source which has been confined within this water zone, " may be partly true, but the results of the lab analysis of the soil borings indicates that contamination from the leaking tanks on the property most likely has also impacted the groundwater beneath the site. In paragraph 2, page 22, a statement is made that the source of the gasoline hydrocarbons found in the groundwater may be the result of an offs1to source. That idea is supported by saying that there is confining zone above the groundwater, and " . . . 30 feet of vertical separation between the deepest known known impacted soil at the site and groundwater. " Groundwater was • measured in the three monitoring wells on the property at about 54 'bg 1 ; TFH--G was found at 40 'bg 1 in the soil bor-i ngs, and Benzene & Toluene were detected as deep as 50'bgl . Erased on County maps, the water table was at 35 'bgl in 1986. Therefore, the statement made in the report is not true. During the placement of the monitoring wells, it was reported that soil samples were collected at 5 foot intervals from 5 'bgl to total depth , and preserved for laboratory analysis. A FID meter was used to screen each sample, and according to the logs included in the report, all readings were below instrument measurement levels. Only the samples at 55 ' & 65 ' bgl were taKen to the lab for analysis. The disposition of the other preserves samples is not noted. It is assumed that because the HID meter did not measure any hydrocarbons, the person on site decided that none of the samples were contaminated. Tnerefore, none of the samples above 55 ' were analyzed. Even when FID meters are accurately calibrated, the readings are not reliable or accurate enough to be used for determining whether or not a sample is contaminated. FID and other indirect methods of measurement are not accepted by environmental health agencies as evidence of lack of contamination - laboratory analysis must be used for confirmation. Therefore, it is not possible to state that the soil samples taken during placement of the monitoring wells were clean. i 3