October 5, 2010
Ecology surveyed the lake today and again found no new oil entering the lake. Sheen on the lake is greatly diminished and is mainly confined to the area of cattails where the storm drain outfall drains to the lake from the property where the home heating (diesel) oil leak occurred.
Cleanup contractors – working for the homeowner whose oil tank leaked – have today been changing oil-absorbing pads within the cattail area. These pads have been effective at recovering oil in the past week and still may be effective at recovering some very sheltered diesel trapped among the vegetation. Absorbent boom securing this area will not be removed until no oil remains in the cattail area, likely another week.
The tank on the spiller’s property has been successfully removed, along with soil contaminated with diesel directly beneath the tank. The next step will be to assess levels of contamination in the storm drain system and adjacent soils. If oil is found there contractors will flush the storm drain system to remove residual oil or excavate the impacted soil around the drain lines. The final step in remediation of the property will be sampling to confirm no oil remains. The soil remediation phase of the cleanup is not performed as an emergency response and may take several days or even weeks.
I have received some questions from community residents asking if there will be shoreline cleanup or removal of contaminated soil along the lake shore. This will not occur because the lake and shoreline habitat would sustain far more damage through mechanical removal than the diesel sheen itself may have cause. In addition, given the relatively small quantity spilled to the lake, diesel evaporates readily and is very susceptible to microbial degradation. The only soil that will be removed is the soil directly contaminated on the property where the spill occurred.
Please feel encouraged to continue to send me any questions or concerns.
October 1, 2010
Today’s Ecology survey showed no new oil has entered the lake or the storm drain system.
The survey included the area of cattails where the storm drain outfall drains into the lake, and the north end of the lake where brown scummy oil was reported.
Oil absorbing pads have been effective in the cattail area, and Ecology personnel replaced numerous oiled pads with fresh pads. Response contractors hired by the spiller will change out oiled pads for fresh pads on Monday, October 4. Absorbent boom will remain in that location until there is no risk of new oil entering the lake.
The brown scum on the north end of the lake was found to be microbial growth mixed with some wind-driven sheen. Ecology will not direct the spiller to have the microbial growth removed. This microbial growth is likely the result of natural bacteria degrading and feeding off of the spilled diesel fuel. Ecology is coordinating with King County Water Quality to ensure that this microbial growth is not a threat to water quality and oxygen levels in the lake remain stable.
Contractors working for the spiller plan to begin removing the broken tank and contaminated soil on Tuesday, October 5. Ecology detected no new oil in the storm drain system on the spiller’s property, but absorbent material will remain in those drains until the soil cleanup is complete.
Oil sheen likely will remain on the lake for several more days. If you find oil that you suspect is recoverable, or if you have any questions about the spill, please do not hesitate to contact Chris Wilkerson with the Department of Ecology Spill Response team.
September 28, 2010
Environmental cleanup crews are working to remove home heating oil from Spring Lake near Maple Valley in King County. A kayaker discovered a sheen (thin coating) of oil on the water Sunday, September 26, 2010, and reported it to the Washington Department of Ecology at 3:50 p.m.
The lake has an electric-only motor rule for boats, so Ecology investigators suspected a home heating oil leak. Monday morning, the source was identified at an above-ground heating oil tank at a home on the southeastern side of the lake. The homeowner cooperated with Ecology's response by hiring an environmental cleanup company.
Crews from that firm could be seen in action on and around the lake Monday, placing material that can draw up oil from the thin layer floating on the lake surface. Responders hope to clean out oil that is trapped among reeds, cattails and other vegetation along the lake shore. Boats also towed long sheets of this material to sweep oil from the open water.
The leaking above-ground tank contained an estimated 200 gallons. Cleanup crews have removed about 150 gallons from the tank. Ecology estimates about 10-20 gallons flowed through storm drains at the home into the lake. The rest soaked into the soil or was caught by storm drain catch basins. Cleanup crews have recovered some oil from the catch basins on the property and have flushed the drain line as well.
The cleanup team has placed boom at the storm drain outfall to the lake as a precaution to protect the lake from further oil releases.
Soil tests will be necessary to plan digging to remove dirt contaminated by the spill. Ecology suspects the bulk of the spilled oil flowed into the soil. The response effort will turn to ground cleanup, next.
Ecology surveyed the lake and found that sheen (a thin coat of oil on the surface) remains present amidst cattails, reeds and other vegetation along the east bank. The sheen – measured in just a few molecules – is too thin for recovery. The pads and strips used for cleanup cannot remove such thin oil sheens off the water. The oil degrades over time, but this can be slow in calm water and mild temperatures. Ecology opted to hold back on a more aggressive shoreline cleanup approach, because potential damage there could outweigh benefits from removing oil more quickly.
Sheen may remain visible for several more days. Material is in place to prevent oil from floating to new areas.
The survey team also determined that no more oil is entering the lake. However, further cleanup of the homeowner’s drainage system is needed.
The bulk of today’s response occurred in planning work. In addition to the storm drain, the bulk of the spill likely is in soil on the homeowner’s property. Over time, this oil can travel with groundwater and potentially reach the lake. It may take several days or more before soil excavation can take place. In the meantime, continued monitoring will occur to ensure that no oil enters the lake from the property.