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Site Background Information
<br />AGE Project No. 13-2557
<br />Page 3 of 4
<br />AdvancedGeo
<br />Environmental
<br />-Ogg
<br />PREVIOUS INVESTIGATIONS
<br />On 15 and 16 May 2017, AGE advanced eight soil borings (B1 through B8) to assess the
<br />lateral and vertical extent of petroleum hydrocarbon impact to the subsurface of the site.
<br />Field procedures were outlined in the AGE-prepared, Preliminary Site Assessment Work
<br />Plan, dated 11 July 2017.
<br />Soil borings B1 and B2 were advanced off-site, on the west side of Holly Drive at 1101
<br />Holly Drive; borings B6 and B8 were advanced on the adjacent property to the north at
<br />1120 Holly Drive; and the remaining borings (B3, B4, B5 and B7) were advanced on the
<br />site at 3 East Eleventh Street. Soil boring B1 was advanced to 16 feet bsg; borings B3,
<br />B5, and B7 were advanced to 20 feet bsg; and borings B2, B4, B6, and B8 were advanced
<br />to 40 feet bsg. Soil boring locations are depicted in Figure 2.
<br />Grab groundwater samples were collected from borings B1 through B8 between 10 and
<br />15 feet bsg and from borings B2, B4, B6, and B8 at a total depth of 40 feet bsg (37-40
<br />feet bsg).
<br />Based on the data collected from borings B1 through B8, silty clay was encountered at 5
<br />feet bsg, from 9 to 10 feet bsg, from 14 to 15 feet, and at 20 feet bsg in most the borings;
<br />and fine-grained silty sand was encountered from 10 to 11 feet bsg and from 15 to 16 feet
<br />bsg in most of the borings. Soil was moist to very moist between 9 and 11 feet bsg and
<br />became saturated at 14 feet bsg. Hydrocarbon-like odor was observed in samples
<br />collected at 10 feet bsg from boring B1 and at 15 feet bsg from each boring, except for
<br />B6. Organic vapor was detected at significant concentrations using a PID in samples
<br />collected from borings Bl, B2, B3, B5, and B7; The highest concentrations were detected
<br />in samples collected from B3 between 14 and 15 feet bsg (473 parts per million volume;
<br />ppmv) and from B5 between 14 and 15 feet bsg (421.8 ppmv).
<br />TPH-g were detected in a total of five (5) soil samples collected; TPH-g was detected
<br />from borings B2, B3, B5, B7, and B8 at 15 feet bsg at concentrations of 19 mg/kg, 330
<br />mg/kg, 200 mg/kg, 23 mg/kg, and 260 mg/kg, respectively. Total xylenes were detected
<br />in the soil sample collected from boring B2 at 15 feet bsg at a concentration of 0.010
<br />mg/kg. Total lead was detected in all twenty-two (22) soil samples collected from borings
<br />B1 through B8 at concentrations ranging between 6.0 mg/kg and 16 mg/kg. Analytical
<br />results of soil samples are summarized in Table 1 and the estimated lateral distribution
<br />of absorbed TPH-g is depicted in Figure 3.
<br />TPH-g were detected in shallow groundwater samples collected from borings Bl, B2, B3,
<br />B5, B7, and B8 at concentrations of 46,000 micrograms per liter (pg/I) in B1, 26,000 pg/I
<br />in B2, 8,100 pg/I in B3, 9,800 pg/I in B5, 440 pg/I in B7, and 540 pg/I in B8. Various BTEX
<br />compounds were detected in shallow groundwater samples in borings B1, B2, B3, B4,
<br />and B8 at maximum concentrations of 62 pg/I benzene in B2, 35 pg/I toluene in B2; of
<br />150 pg/I ethylbenzene in B1 and B2, and 210 pg/I total xylenes in B1. Naphthalene was
<br />detected in shallow groundwater samples collected from B1, B2 and B3 at a maximum
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