Spill volume at Drift River still unknown

The spill volume at Drift River is still unknown, the Alaska Department of Environmental Conservation’s Division of Spill Prevention and Response said in an Aug. 16 update. There were two spills at the Cook Inlet Pipeline Co.-operated facility on the west side of Cook Inlet (see stories in Aug. 7 and 14 issues of Petroleum News). The first was discovered July 2 and the second July 28. Both were associated with over pressurization of the 20-inch fill line, DEC said.

In its Aug. 16 update DEC said free product was discovered Aug. 10 when a buried flange between tanks 2 and 3 was being excavated. The spill volume is unknown, but CIPL will submit an estimated spill volume as part of its final report.

DEC said the crude oil remaining in the 20-inch line was being transferred to a marine tanker that arrived Aug. 15. The free floating oil was discovered Aug. 10 when CIPL exposed three-quarters of the buried flange and “free product started to gather at the excavation center point and rise up with the groundwater.”

CIPL then delineated contamination with test holes from the 50-foot square edge and worked toward the excavation center to avoid spreading the oil.

DEC said the delineation found in the test holes “showed contamination extended only a few feet outside of the initial excavation area.” CIPL’s environmental contractor then collected soil and water samples for analysis.

CIPL collected the free product using approximately 60 sorbent pads. DEC said no additional oil has been observed seeping into the excavation area.

Once delineation was completed where oil was found between tanks 2 and 3, CIPL and its contractor began delineating the surface area found stained with oil July 28, using a grid system with probes and excavating test holes. DEC said the horizontal area of contamination was found to be approximately 40 feet by 60 feet.

Sheet pilings are required to shore up the sides of the excavation and those are expected to arrive the weekend of Aug. 20-21, DEC said, and once those arrive, CIPL can begin to excavate contaminated soil.

- KRISTEN NELSON