Spotlight on Former Orchard Land Cleanup in Central Washington for New Housing

In Washington state’s agricultural hubs – Wenatchee, Yakima, and Chelan – former orchard land is being redeveloped to meet housing demands. Aspect has worked on several projects that are safely turning these brownfield sites into new housing for residents.  

As the Washington State Department of Ecology recently detailed, former orchard lands have a history of pesticide use, and the type of pesticides used has changed over time. Orchards that were active between 1900 and 1950 generally used lead arsenate, which left residual concentrations of both lead and arsenic in near-surface soil at concentrations above Ecology’s cleanup levels.

Example of former orchard land in East Wenatchee, where new housing now sits.

Snapshot of Former Orchard Land and Cleanup Process

Ecology has classified these former orchards with potential lead arsenate contamination and included them in their publically available ‘Dirt Alert’ program (based on historical aerial photo interpretation and other methods). As shown in the image below, orchard lands are generally concentrated in the Columbia, Yakima, Okanogan, and Wenatchee river basins throughout central Washington.

Using Ecology’s publicly available Dirt Alert mapping, see land (yellow on map) that Ecology delineated as orchard during the lead arsenic era: 1900-1950

Project Spotlight: Cleanup and 20 New Residential Homes near Chelan, WA

Aspect recently supported Chelan County to cleanly ‘cap’ the soil at a former orchard residential redevelopment in Manson near Lake Chelan for 20 new homes so it would protect human health and the environment. Chelan County Natural Resources Department used an Ecology grant to evaluate the costs associated with implementation of a Model Remedy (that is, a clean cap remedy) for this ‘trial implementation’. Aspect supported Chelan County by:

• Sourcing and analytically testing clean soil cap sources

• Sourcing and calculating soil amendment (compost) requirements for lawn support

• Construction sequence and contractor coordination

• Cost tracking

The trial found that the cost of implementing the clean soil cap model remedy amounted to approximately $5,000 per parcel.

Model Remedies Cleanup for Agricultural Owners and Developers

Model Remedies can guide property owners, developers, and consultants to clean up these lead arsenate properties efficiently and protect the community. Contamination is often limited to just the topsoil layer, thus reducing the complexity of cleanup. There are a few routes to cleanup:

• Excavation and off-Site disposal is a conventional clean-up method that in most cases is too costly for a residential redevelopment.

• Capping is a model remedy in which the contaminated soil remains on site and is “capped” with asphalt, building foundations, and delineated landscaping beds and is generally the most cost-effective model remedy.

• Mixing is a solution where the soil column is mixed until contaminant concentrations throughout the soil layer are all below cleanup levels. A mixing model remedy could be applicable when contamination is limited to a very shallow depth.

Capping is the most commonly used cleanup method in the Model Remedy process. Capping keeps residential communities safe by providing a physical barrier (such as asphalt or colored demarcation fabric beneath the topsoil) between residents and the contaminated soil. Lead arsenate is generally contained within the near-surface soil, so there is no exposure risk related to drinking water or using groundwater. Also, because metals do not vaporize, there is not a threat of vapor intrusion into structures.

Contact Aspect’s Breeyn Greer and Adam Griffin for more information about the cleanup process for orchard redevelopment.

Reducing Risk and Uncertainty: A PCE Site, a Model Remedy, and an NFA

No Further Action (NFA) determinations are Washington state’s sought-after finish line for regulatory closure of contaminated sites. An NFA is often the stepping stone for a property owner to secure financing for development of their property and alleviate concerns that their property won’t be put to productive use. NFAs are not easy to get—particularly for former dry cleaner sites, where perchloroethylene (PCE; a dry-cleaning solvent) is a common culprit that can keep a property in regulatory limbo and cause cleanup timelines to be counted in years.

Not a Typical Cleanup: Applying a Model Remedy at a Chlorinated Solvent Site

Aspect had a recent success story where we helped a client achieve an NFA by pursuing site closure through Ecology’s Initial Investigations program using a Model Remedy approach. The premise of this approach is that if you can completely address or clean up a release upon discovery, then you may be able to request an NFA at the initial investigation/reporting stage, thereby circumventing the Voluntary Cleanup Program process.

Identifying and excavating the contaminated soil from inside the store led to a successful No Further Action determination for the Site.

The project site, located in Kent, was a former dry cleaner with PCE impacts limited to shallow soil around the dry-cleaning machine. Following Aspect’s Phase I/II ESA investigation as part of a pending property transaction, we implemented a cleanup action after our client purchased the property. The space inside the store was limited, and the excavation was surgical. Confirmation soil sample results following the excavation were below Model Toxics Control Act (MTCA) Method A cleanup levels. Instead of entering the VCP and facing delays with Ecology’s backlog of VCP sites, we instead reported the release to Ecology within the framework of a Remedial Investigation and Cleanup Action Report, with the completed excavation and off-site disposal of contaminated soil presented as a model remedy.

Reducing Risk and Uncertainty

After follow up discussion and negotiation with Ecology’s Initial Investigations coordinator, the site recently received an NFA. Though there may not be many PCE-impacted sites where the contamination is limited to shallow soil, it pays to know the options if this is the case. Model remedies are more commonly applied to petroleum-impacted sites. However, because Aspect was on the lookout and understood the regulatory framework for achieving closure, we were able to help our client significantly reduce risk and uncertainty when weighing prospective property purchases.

The Model Remedy approach is a strategy that Aspect has used on several sites with success and, under the right set of circumstances, can be an efficient regulatory pathway for property owners seeking an NFA.

Contact Eric Marhofer or Doug Hillman to learn more.