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R&L Diesel Addendum Letter- Project#051111 <br /> September 15, 2009 Takw <br />/1 Page 2 srRce 1954 <br /> Mass Balance Calculations <br /> Soil samples from under a UST closed in place in April 1988, evidenced the presence of <br /> diesel and VOCs from approximately 14 ft. below grade to 29 ft. below grade, within a 4 ft. <br /> radius of the center of the tank. Samples at 6 ft. belo grade and 44 ft. below grade, at a radius <br /> of 4 ft. from the center of the tank showed no hydrocarbons above laboratory detection limits. <br /> Samples from 14 ft under grade to 65 ft. under grade, at a radius of 7ft 4 in. from the center of <br /> the tank showed no hydrocarbons above laboratory dE tection limits. In summary, testing <br /> showed impacted soil in an 8 ft. diameter by 15 ft. (29 . below grade— 14 ft. below grade) <br /> cylinder below the UST. The average concentration w 3s 5643 mg/Kg diesel and 563 ug/Kg <br /> VOCs. This represents the extent of impacted soil act jally tested. Allowing for impacts beyond <br /> the area actually tested, but within the area testing as on-detect (44 ft. below grade, 4 ft. <br /> radius, and 7 ft. 4 in radius at all depths), use the folio ing as a basis for calculating the amount <br /> of constituent of concern mass remaining: <br /> Impacted area = 8 ft. diameter x 25 ft. = 1256 cu. ft. <br /> Concentration levels = 5000 ppm diesel and 550 ppb OC; <br /> Then constituent of concern mass remaining: <br /> = 1256 ft3 x 100 lb.lft3 x 5000 Ib.11000000 lb. <br /> = 628 Ib. diesel = 90 gal. diesel (based on ap rox 6.98 Ib per gallon) <br /> = 1256 ft3 x 100 lb.lft3 x 550 Ib.11000000000 lb. <br /> = 0.07 Ib. VOCs. <br /> Geotracker Uploads <br /> The EDF for the laboratory analytical results from the site assessment, the boring log <br /> from B-5 and the site map were uploaded to Geotracker as of September 15, 2009. This letter <br /> addendum is anticipated to be uploaded to Geotracker on September 16, 2009. <br /> Should there be any questions concerning this eport, please do not hesitate to call us. <br /> Very truly yours, <br /> T BER CONSULTANTS <br /> THOM"L� <br /> Thomas E. Ballard <br /> 4s�q <br /> Senior Geologist <br /> �F CAttP.Q. #7299 <br /> cc: Mr. Joseph Rokoszewski, RBL Diesel <br /> Mr. James Barton, Central Valley RWQCB <br />