Landmark Care Center

In 1994, a Phase I Site Assessment was conducted at the Landmark Care Center site. It was determined that the site had operated as an orchard for approximately 40 years, and was likely to contain residual pesticide area-wide soil contamination. Soil samples collected from the site were found to have levels of lead, arsenic, and DDT exceeding state cleanup levels.

For this site, it was determined that management of impacted media on-site would be the most appropriate remedial action. This remedial option was preferred over other options because impacted media was pervasive across the entire site and excavation and disposal would have subjected the owner to costs disproportionate to the net environmental benefit.
 
All media suspected of having residual concentrations of agricultural chemicals could be effectively used on-site for fill material. Preliminary investigations on behalf of the owner indicated that site soil should be suitable for compaction. Considering probable duration of historical application of chemicals at this site (~1930 - 1970), observed depth of maximum downward migration of residual chemicals is consistent with predicted low leachability of metals in soil. Given the low mobility of chemicals and the distance to groundwater at this site, managing soils onsite will effectively prevent groundwater impact.
 
At completion of site grading and construction, soils not covered by impermeable capping material (asphalt or building footprint) were capped with clean topsoil and vegetation or landscaping. Confirmation of remediation was verified by sampling of surface capping material. Post-remediation arsenic analysis documented one area in the upper 6 inches above the selected remedial threshold. Post-remediation arsenic statistical analysis had a mean site value of 7.42 milligrams per kilogram (mg/kg), a range of 2.2 to 29.5 mg/kg, and an upper confidence level of 9.73 mg/kg.

Because contamination was capped at the site at concentrations exceeding Model Toxics Control Act (MTCA) Method A cleanup levels, institutional controls were required for the site to be eligible for a no further action determination. An environmental covenant was recorded for the site in 2010.

Based upon cleanup activities and the recording of the environmental covenant, Ecology has determined the site is no longer a threat to human health and the environment. Ecology issued a no further action determination in May 2010.

Periodic reviews are conducted every 5 years by Ecology for sites that have institutional controls. The review is intended to examine the effectiveness of cleanup activities and to assure the continued protection of human health and the environment.

Periodic review results

Based on site visits conducted in 2010, 2015, 2021, the cleanup actions completed at the site are protective of human health and the environment.

Soil cleanup levels have not been met at the site; however, the cleanup action is determined to comply with cleanup standards under WAC 173-340-740(6)(f), since the long-term integrity of the containment system is ensured and the requirements for containment technologies have been met.

The environmental covenant for the property is in place and will be effective in protecting public health and the environment from exposure to hazardous substances and protecting the integrity of the cleanup action.

Based on the periodic reviews, Ecology has determined that the requirements of the covenant are being followed. No additional remedial actions are required by the property owner. It is the property owner’s responsibility to continue to inspect the site to assure that the integrity of the cap is maintained.