FIELD DOCUMENTS_FILE 1 - Laserfiche WebLink

Home Browse Search

09 August 1999 $- AGE-NC Project No. 98-0466 r Page 4 of.10 excavation was not specif cally-noted in either document although soil sample localities were shown f near the `Pump& Island' south of the UST and adjace t,building. . Excavation of impacted soil south of the former UST an adjoining building was conducted between " 10 March 1994 and 28 March 1994. PHS-EHD'field notes for 11 March 1994 note that.the lateral extent of contamination appeared to be defined, but odor was present at 13 feet bsg. The 24' x 30' x.13'deep excavation of 11 March 1994 was expanded to a 20'x 30'x,45' deep excavation and ramp by 28 March 1994.Excavation and stockpile soil sampl ,s were collected on'22lMarch 1994 and 28 March 1994. The 22 March 1994 excavation soil sample(N 1-22)collected on the north wall of the excavation at a depth of 22.feet bsg;did not contain det ctable concentrations of TPH-g, TPH-d oi• BTEX compounds.Figure 2 shows the area-of the excav tion as reconstructed from field notes made during excavation and.observations,made by GeoAudit Inc. on the site. Three soil samples were"collected froni the excavation bott61n, at 45 feet bsg, on 28 March'1994:; Soil stockpiles'composed-of soil removed`toconstruct iramp into the main excavation were also sampled for laboratory. analysis. TPH-d and BTEX com rounds were not detected in the excavation _ bottom soil samples. TPH-d was detected in four out o five composited stockpile soil samples at concentrations,as high as 210 mg/kg. Only 0.01-3-mg/Ig xylenes were detected in one composite stockpile soil sample; BTEX compounds were not det cted in the-other four composite samples. I Table,2 shows the data obtained.from theMarch 1994 Soil samples. Between 28 March and 20 April ;1994, the excavation as backfilled. On-20 April 1994; the soil stockpiles-composed of excavated hydrocarbon-impacte soil were sampled.for laboratory analysis r for characterization. TP,H-d was detected in five of nine tockpile soil samples at concentrations as high'as 7,300 mg/kg. Low concentrations of toluene,et ylbenzene and/or.xylenes were detected in seven'samples at concentrations as high as 47 mg/kg (xy ene's). Benzene was not-detected in any of r the samples-analyzed. Analytical results-for the sample are presented in Table 3. ,2:3. MASS'OF EXCAVATED HYDROCARBONS: . Without benefit of an initial site assessment, the extent of the hydrocarbon impact to soilmust be inferred from the extent of the excavation and analytical results of samples.collected from during the UST removal and collected from the soil stockpiled during excavation of the impacted soil. Results from confirmation samples and from what AGE interpr is to have been the ramp excavation were not utilized. The sampling and excavation was performed under PHS-EHD observation. The exact volume of:impacted soil removed from the site is not clear from the notes available to AGE,but one document calculates removal of 666 cubic yards of impacted soil. Some impacted soil was apparently removed-during cutting of the ramp into the deep excavation. AGE calculates that excavation of a 23' x 23' area to a depth-of 45 feet woul� remove'881 cubic yards, not all of which Advanced CeoEnvironmentei,Inc.