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1 Staff Report: DIAMOND WALNUT GROWERS 1050 DIAMOND ST Date: May 17, 1994 Staff: Diane M. Hinson Additional Soil Assessment and 4th QMR - UST Vaults Question regarding the material stored in vault 18: Resna indicated in a footnote that their review of purchasing reports of materials bought for storage in the vaults documented that 10 barrels of ethylene glycol were inadvertently purchased. Of the ten barrels, and only 2 barrels of ethylene glycol were unaccounted for since the others were returned to the vender for credit. In my discussion with Gregory Stahl, Resna, in the later part of 1993 in the 3rd QMR Resna supported data that the rapid degradation of glycols and degradation products resulting from the resultant byproducts would be unlikely as to provide a significant source of groundwater contamination. Based upon the research that Resna had performed, PHS/EHD expressed concurrence with these findings; therefore, additional soil investigation was not conducted in the vicinity of the glycol tanks with respect to the contaminant ethylene or propylene glycol. To further define the extent of soil contamination in the vicinity of former vault #8, Resna supervised the drilling and sampling of two additional soil borings; SBI and SB2, drilled by Spectrum Exploration. Soil borings were advanced to a maximum depth of 80 feet; sampling at 10 foot intervals. All samples were analyzed for total and soluble total chromium, EPA 6010 and 7191, respectively; total hexavalent and soluble hexavalent chromium, EPA method 7196. In addition, 2 samples from each boring were analyzed for magnesium, EPA method 200.7; and pH, EPA method 9045. SBI was found to consist predominantly of elastic silts, lean to fat clay lenses from the surface to approximately 51 feet below grade, and poorly to well graded sand with silt and silt with sand from 51 to 81 fbg; the TD explored. Aanged ra a of total chro level¢¢ from 10 - bgg,, was 3&7-Y—at� fromg t tal chromium vels rangedfrom 28-43 ppm bolubleomiumngel rom .65 - 3. 5 ppm f om 10 - 40 fb from 0 - 80leomium levels ran a from <. 10 -0.14 pp � 'Eotal exavalumnged2 0 - 11 pp from 10 - 0 fbg; <. 0 - 1.2 m frobg.exaval nt chr ium levels ra ged fr -<.005 0.11 pm from 5 - m t_pp fog. level%ranged from 6.9 at 40 a SB2 consisted of poorly graded sand with silt and silt with sand from the surface to approximately 70 fbg. Elastic silt and lean to fat clay interbedded with sand lenses from 17 fbg to 72 fbg; and poorly graded sand from approximately 72 fbg to 81 fbg to TD explored. The range of total chromium levels from 10 - 40 fbg was 25 - 77 ppm; from 50 - 80 fbg total chromium levels ranged from 29 - 48 ppm; and soluble total/ chromium levels ranged from .99 -1.6 ppm from 10 - 40 fbgi - 8 bg -fne soluble chromium levels ranged from <0.1 - 1.3 ppm Total romium levels ranged from 2.2 -3.5 ppm from 10 - 40 fbg; 50 - 80 fbg ranges were <0.5 - 1.0 ppm; soluble hexavalent chromium levels ranged from .13 -1.3 ppm from 10 - 40 fb , 50 - 80 fbq ranges were <.005 - 09 ppm,,T-M—anganese levels 560 ppm a fbg to 1200 ppm at 80 fbg; pH levels ranged from 7.4 at 40 fbg to 7.5 at