ARCHIVED REPORTS_XR0004165 - Laserfiche WebLink

Home Browse Search

f� KEI-P91-0202.QR1 May 4 , 1992 Page 4 Water and selected soil samples were analyzed at Sequoia Analytical Laboratory in Concord, California. Soil and water samples were analyzed for TPH as gasoline and BTX&E. Analytical results of the soil samples collected from the borings for monitoring wells MW1 , MW2 , and MW3 indicated lion deteable levels of TPH as gasoline and BTX&E, except for samples MW,1(2 ) IMW1:(32 .5 �; �ai d�M_.i(_4.2_._5 , which showed levels of TPH as gasoline ranging from 1. 9 ppm to 5. 0 ppm, and levels of benzene ranging from 0. 45 ppm to 1.9 ppm. In addition, sample MW1 (37 . 5) showed a benzene level of 0. 0094_ppm.. Re�late �elry; ninor,�,.amounts,o€ o uen xylenes; :;an&ethy bei,zene--were-a-iso-det,_ected in the t'-f-ou sample. Analytical results of the collected on 2 September 9, 1991, from monitoring wells :MW1 Arid MW indicated _w levels of TPH'4as.:gasoline `at E6U ppb. and 24^0 pp , respectivel T. w_ t beia'xene levels a '96 p 'b and 13 ,-ppb, respectively. In NWo' , TPH as gasoline was non-detectable, with 6 z.ene' at 0. 49 ppb The results of the soil analyses are summarizedin TabYe 4, and the results of the water analyses are summarized in Table 2 . Based on analytical results, KEI recommended the implementation of a monthly monitoring and quarterly sampling program of the existing wells. In addition, wells MW1, MW2, and MW3 were recommended to be redeveloped during the following quarter, due to observations made during the initial ground water sampling activities that indicated the presence of some sa _ a d_silt materials at the bottom of the well casings. t should a ='rioted tYiat„ because .,the wells `were y� comp,lee d;_the nal samples � _ co l �ected. Rer+om. these �smakyot� be re resentative of the"actual round mat=er=quality at. the site. ) At Unocal ' s request, on December 16 through 20, 1991, six addi- tional two--inch diameter monitoring wells and two exploratory borings (designated as MW4 through MW9 and EBI and EB2 , respec- tively, on the attached Site Plan, Figure 1) were installed at the site. The six wells were each drilled and completed to total depths ranging from 79 to 85 feet below grade, except for MW5, which was drilled and completed to a depth of 70 feet below grade. Ground water was encountered at depths ranging from 71. 5 to 75 feet beneath the surface during drilling, except in MW5 , where ground'r water was encountered at a depth of 60 feet below grade,: The exploratory borings were drilled to depths of 20. 5 and 21.0 feet below grade. The surface of each well cover was surveyed by Kier & Wright of Pleasanton, California, to MSL and to a vertical accuracy of 0. 01 feet.