ARCHIVED REPORTS_XR0008855 - Laserfiche WebLink

Home Browse Search

15 November 1996 AGE-NC Project No 95-0143 Page 2 of 4 22 COLLECTION OF GROUND WATER SAMPLES Water samples were collected from each purged well using new disposable bailers and were transferred into 40-m1 EPA vials The samples were tiansported under chain of custody in a chilled container to McCampbell Analytical, Inc in Pacheco California(MAI), and were analyzed for total petroleum hydiocarbons quantified as gasoline (TPH-g), and for volatile organic compounds I (benzene, toluene, ethylbenzene and xylenes BTE&X) with methyl-tertiary-butyl-ether (MTBE) in accordance with EPA methods 5030 and 602 iespectively 3.0 FINDINGS 3 1 RELA FIVE GROUND WATER ELEVATION AND GRADIENT The relative ele,.ation of ground water in each well was calculated by subtracting the depth to water from the sure}ed casing elegy ation (Table 1) Ground water rose an average of 1 97 feet between February and May 1996 Ground water rose an average of 0 23 feet between May and August 1996 The approximate gradients were calculated to be 0 0056 ft/ft and 0 0063 ft/ft north of the site corresponding to gradients measured at the Madison site However, shallowe7 gradients of 0 0017 ft/ft and 0 0018 ft/ft were measured on the subject property Flow directions were generally toward I the north Relair,e ground water elevation contours for the May and August 1996 monitoring events are illustrated as Figuies 3 and 4 I .32 ANALYTICAL RESULTS OF WATER SAMPLES TPH-g was detected in samples from MW-6 MW-7 and MW-9 at concentrations of 6 500 parts per billion (ppb reported as microgiains pen liter) 15,000 ppb and 42,000 ppb, respectively during the May 1996 monitoring TPH-g was detected in samples from MW-3, MW-6, MW-7 and MW-9 at concentrations of 300,000 ppb, 6,100 ppb 24,000 ppb and 21,000 ppb, respectively, during the August monitoring BTE&X were detected in the same wells at concentrations as high as 60,000 ppb (toluene,MW-3) Benzene was detected in wells MW-6,MW-7 and MW-9 at concentrations ranging from 250 ppb to 1,100 ppb during the May monitoring event, and in MW-3, MW-6, MW-7 and MW-9 at concentrations ranging from 330 ppb to 24,000 ppb during the August monitoring event MTBE was detected in MW-7 and MW-9 at concentrations of 20 ppb and 140 ppb, respectively, during the May 1996 monitoring MTBE was detected in MW-17 at a concentration of 7 ppb during the August monitoring Free product was encountered in MW-3 during the May 1996 monitoring, therefore,no sample was collected Petroleum hydrocarbons were not detected in samples from MW- 10, MW-14, MW-15 or MW-16 during either sampling event Analytical results are summarized on Table 2 The laboratory report (MAI Laboratory I D Nos 64901 - 64908, 67772-67780) and chain- I I