Despite the removal of more than 35,000 tons of toxic soil in 2010, the City of Bothell still has some time before the Department of Ecology deems five parcels of land in downtown Bothell as having reached proper cleanup levels.

Nduta Mbuthia, a project engineer with the city, said before the city can conduct a year’s worth of groundwater monitoring (under Ecology’s oversight) to determine if contamination has been resolved, the city needs to complete additional cleanup under State Route 522, which is near two of the sites.

“The sites are currently a construction zone, as the city is conducting cleanup work under the Bothell Crossroads project,” Mbuthia said in an email, “which means that with all the equipment currently running around on the site, we have to wait until the area is vacated.”

Mbuthia said SR 522 will be vacated this fall and that officials have been removing small pockets of contaminated soils during the roadway project, which will shift SR 522 onto four of the parcels of land. These include the Bothell Riverside, Bothell Landing, former Hertz property and former Bothell Paint and Decorating sites, located just south of the current SR 522 roadway, which are under formal agreed orders with Ecology.

Areas to the east of Northeast 180th and the intersection between SR 522, SR 527 and Main Street may also require cleanup. But cleanup wouldn’t begin until the new SR 522 road is completed, therefore “the traffic impacts would be much less,” said Mbuthia.

In 2010, as a part of Bothell’s Downtown Revitalization Plan, City officials (under Ecology oversight) removed 12,000 tons of contaminated soil at the Northshore School District’s former bus barn, 6,000 tons of contaminated soil at the Bothell Paint and Decorating site, 12,500 tons of contaminated soil at the former Hertz site (also known as the AA Rentals location), 3,600 tons of contaminated soil at the Bothell Landing site and 1,000 tons of contaminated soil at the Bothell Riverside site. The total weight is equivalent to about 2,700 school buses.

After the soil was removed from all sites, it was trucked off to a Title D disposal facility and the excavations refilled with clean dirt imported from a quarry.

Workers plan to pump out contaminated groundwater at the Bothell Riverside site this year because its groundwater was also found to have chlorinated solvents running through it. A public comment period will be available in either February or March.

Before the city purchased the four pieces of land for the Bothell Crossroads project, investigators discovered the former Hertz site was once owned by a petroleum company in the 1930s and underground storage tanks (USTs) had been removed from the property in 1993. An Ecology fact sheet states that in 2008 the city complied with environmental site assessments, and as a result, petroleum hydrocarbons were detected in soil and ground water.

Vinyl chloride and arsenic were found to exceed Washington state cleanup levels and can be dangerous for those who experience toxicity. Tetrachloroethene and trichloroethene were also found at the Hertz site but were below cleanup levels.

But some chemicals from dry cleaner solvents – liquid used to dissolve substances – were detected, which “may have migrated in groundwater and affected several downhill or down-gradient properties,” according to Mbuthia. The solvents may have been from local dry cleaner businesses from the 1950s.

Petroleum contamination was found at all five sites, including the Northshore School District property. The Northshore School District’s property housed their transportation facility and bus maintenance shop and, according to the city’s website, contamination was caused from leaking hydraulic hoists in the maintenance shop and from abandoned fuel tanks. Various heavy metals and polycyclic aromatic hydrocarbons, which are known to be carcinogenic, mutagenic and teratogenic, were also found at the Northshore School District property. However, up until the Northshore School District sold the property to the city in 2010, they managed their site independently with Ecology’s Voluntary Cleanup Program (VCP). The site must still reach standards under the state’s 1989 Model Toxics Control Act, said Ecology spokesman Larry Altose. The city has recently reenrolled this site into the VCP.

Funding this environmental cleanup has and continues to be very expensive for the city.

“We still need more money for future cleanup work,” Mbuthia said.

The Environmental Protection Agency granted the Bothell Landing site $200,000 in 2009 for petroleum cleanup and Ecology provided $3.52 million for investigative and cleanup work with the city providing a 50 percent match. And although there is still $2.5 million left to be used, the city still needs $9.6 million over the next seven years for the Crossroads sites and former dry cleaner sites.

“That number ($9.6 million) covers the remaining soil removal (petroleum), future cleanup of solvent-impacted areas (more expensive than petroleum cleanup) and all the groundwater investigation and the multiple quarters of groundwater monitoring that will happen after that,” Mbuthia said.

Funding will come from various resources from the city’s capital improvement fund along with awarded grants. According to City of Bothell documents, the total estimated cost of the cleanup project will reach $14.5 million, of which $4.2 million has been spent to date.

As the city continues to move toward a clean and healthy downtown area, Mbuthia acknowledges “there are potentially other contaminated private properties in Bothell.”

“In the city’s case, investigations of these pieces of land were triggered by a real estate transaction,” said Mbuthia of the city-owned parcels. “In the downtown area, city officials in collaboration with Ecology, the Environmental Protection Agency (EPA), King County Brownfields Program/ECOSS and various entities have done a lot of investigative work to understand the contamination, and continue to do so.”

According to a 2008 Report on Tax Parcel History through 1972, there are 18 other parcels of land in Bothell that may be contaminated. This includes the gas station site that is north of the property where McMenamins will be constructed in July 2013.

For more information on the Downtown Contaminated Soil and Groundwater Cleanup program, visit this website.