Problems/Comments

Historical aerial photographs indicate extensive warehousing activities occurred near the proposed Montgomery Road extension. Rows of drums stored on a gravel pad for many years suggest the potential for buried drums; petroleum, oil, and lubricant (POL)-contaminated soil; and chlorinated compounds. 2010 field activities were conducted in support of future construction activities at this site. Geophysical survey activities were conducted and nine highly anomalous areas were identified for test pitting activities. Several identified anomalies warranted additional investigation. Test pitting began in the center of each identified anomaly and the direction and location of any expansions were based on field observations. The depths of the test pits were determined according to the bottom depth of identified debris. All debris was removed and each test pit was backfilled accordingly. Approximately 5 cubic yards of POL-contaminated soil was excavated. Thirteen samples were collected during test pitting activities. Samples from Test Pit 2 and Test Pit 4 exceeded the ADEC cleanup criteria for DRO (250 mg/kg) with results of 8,730 mg/kg, 4,050 mg/kg, and 293 mg/kg, respectively. Results from Test Pit 2 also showed exceedances for RRO (28,800 mg/kg and 23,600 mg/kg), lead (528 mg/kg and 1990 mg/kg), tetrachloroethene (0.0487 mg/kg), and benzene (0.0561 mg/kg). Fifty-four soil samples were collected during soil boring activities. Two samples from SB09 at 14 feet bgs and 16.5 feet bgs and one sample from SB13 at 3.5 feet bgs, exceeded ADEC cleanup criteria for DRO (250 mg/kg) with results of 5,910 mg/kg, 3,660 mg/kg, and 900 mg/kg respectively. Five groundwater samples from temporary well points were collected. One groundwater sample from location SB09 exceeded ADEC Table C cleanup criteria for DRO (1.5 milligrams per liter (mg/L)) with a result of 1.6 mg/L. This site also includes a concrete vault identified during the summer of 2010 when an underground sewage lift station consisting of a concrete vault (11.5 feet by 5.5 feet by 18 feet) and six concrete partitioned containment cells were discovered during construction activities associated with the extension of Montgomery Road. A historical as-built drawing indicated the presence of sanitary sewage lines from the containment cells to the Chena River, however, an inspection of the Chena River bank did not indicate the presence of any sewer outfall. In 2010, standing wastewater in the concrete vault was sampled and analytical results confirmed benzene, lead, diesel range organics (DRO), residual range organics (RRO) and polychlorinated biphenyls (PCBs) at concentrations above the Table C groundwater cleanup levels. Additionally, a sediment sample was collected and results indicated, DRO, RRO, 1,4-dichlorobenzene, arsenic, barium, cadmium, chromium, lead, and mercury exceeded Method Two soil cleanup levels. Further investigation in 2011 showed the concrete vault system was abandoned in place after being backfilled by concrete and soil. Wastewater that had accumulated in the vault was removed, treated and disposed of properly. Tabulated analytical results from 2010 and 2011 show lead above the DEC cleanup levels for soil and groundwater, and DRO above the DEC cleanup level for soil. The effluent pipe for the concrete vault has not been located.

Action Information

Contaminant Information

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Requirements

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