An assessment of an oil spill discovered in Nipomo Creek indicates that the mishap has not affected the creek nor the groundwater and has not created a threat to human health - and the review recommends leaving the oil in place rather than excavating it.

Whether regulators adopt that recommendation will depend, in part, upon a feasibility study of the options to be conducted by ConocoPhillips.

“We're still in the process of evaluating the best option, to leave it in place or dig it out,” said Richard Chandler, engineering geologist with the Central Coast Regional Water Quality Control Board. “There are concerns either way.”

Neither bioremediation - using oil-eating microbes - nor vapor extraction are options when dealing with crude oil, especially in clay soil, because those approaches only work on refined products such as gasoline, Chandler said.

“The main problem in leaving it in place is the potential for it to go down the creek and expose plants and wildlife to the oil,” Chandler said. “I agree with the report that there is no risk to human health as a result of this release. The greatest risk is to plant and animal life.

“If we dig it out, it would disturb plant and animal life that's there right now,” he continued. “Then we'd have to do a restoration of the creek. It's not impossible, but it's a major operation.”

Fred Collins, a representative of the Northern Chumash Tribal Council, previously expressed concern that the oil could be washed down the creek. He also worried that remediation work could disturb a Chumash burial ground in that area.

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But Collins hadn't seen the report and couldn't comment on it early this week.

Because the major danger is to plant and animal life, the California Department of Fish and Game will be involved in advising the Regional Water Quality Control Board on what steps to take.

Calls to the Central Region office of the DFG in Fresno were not returned.

Because the contamination lies within a 100-acre property recently purchased by the Dana Adobe Nipomo Amigos to create a historical park around the Dana Adobe, that organization is especially interested in what action is taken.

“DANA's review of the final study by ConocoPhillips of the subsurface contamination is still in process,” said Herb Kandel, president of the organization. “DANA reiterates its concern that the decision that the water board will make, with input from the Department of Fish and Game, must take into account the highest level of protection for natural and cultural resources around the creek down the hill from the adobe.

“The impact of destroying flora and fauna ... in the process of digging up the creek to remove contaminated soils must be weighed with the very real risk of exposure and transfer of the contamination and/or impacts to the local aquifer.”

He said the DANA board plans to take a position on the issue when it meets this month.

Years in the ground

Chandler said no one is sure when the spill occurred, but it was discovered in July 2003 when ConocoPhillips excavated a section of pipeline in the creek just east of the historic adobe after encountering a problem during a pipeline inspection.

He surmised the oil leaked from another nearby 8-inch pipeline that was abandoned years ago by then-owner Unocal and replaced with the new pipeline now owned by ConocoPhillips.

Initially investigated in 2003 and 2005, the spill was reassessed in the report prepared by Terra Pacific Group of Irvine for ConocoPhillips and delivered to the water board Oct. 22.

It indicates the spill is approximately 330 feet long, 220 feet wide and extends from seven to 28 feet below ground level. Located about one mile south of West Tefft Street, the spill in some places is near the surface of the creekbed.

Chandler said no evaluation has been made about how many gallons of oil might have spilled.

“But that's not really critical,” he said. “The concern is whether it will affect human health.”

The report concludes there is no crude oil in the creek water nor in groundwater wells and monitoring wells drilled nearby, although one monitoring well showed low levels of mineral oil that probably came from that well's pump.

Because the ground below the contamination is dense clay, the report concludes there is little likelihood the oil will seep into the groundwater, although it recommends continued monitoring on a semiannual basis.

Chandler said there is a chance the creek could erode into the contamination and send oil down the channel toward the Guadalupe Dunes and, eventually, the sea.

However, he said the area doesn't seem to be eroding, but rather is a swampy area where eroded soil is being deposited.

“But I couldn't say we won't get some storm erosion in that area,” he added.

As to when that might happen, “That's impossible to predict,” he added.

Chandler said the next step is the feasibility study that will evaluate the two options.

“With crude oil, there are really only two options - leave it in place or dig it out,” he said.

Once that study is done and evaluated by the various agencies involved, the Regional Water Quality Control Board will make a decision on what action to take. That decision could come in three to five months, he said.

November 9, 2007