Saddle Rock Regional Park Interim Remedial Action
Remediating heavy metal contamination at a beloved natural area.
Saddle Rock Regional Park is a popular recreation area outside Wenatchee, Washington, known for its dramatic outcropping and sweeping vistas. Unfortunately, prospecting and mining activities from the late 1800s through the mid-1900s left large waste rock piles containing high levels of arsenic and other heavy metals throughout the scenic park.
GeoEngineers won a competitive contract with the City of Wenatchee in 2019 to perform supplemental data-gaps sampling at the park and complete design and bid documents to complete phase 1 of the interim remedial action. In addition to technical support, the GeoEngineers team served as liaison between the City of Wenatchee, the landowner, and the Washington State Department of Ecology, the regulatory and funding authority. GeoEngineers worked hard to find compromises and solutions to project challenges that would satisfy both parties.
At every stage, the Saddle Rock team looked at the project from a client-centered point of view. The presence of some naturally occurring arsenic at the site made it difficult to differentiate waste rock pile limits from background conditions. The team developed a creative approach to the sampling plan, which incorporated analysis of upslope and downslope concentrations of metals to identify statistical differences between the data and address other data gaps. With new sampling data in hand, the team re-evaluated prior data sets and found they could safely eliminate two rock piles from the removal plan, saving the city money.
- Supplemental Sampling: The project team performed supplemental sampling and used their findings to prepare a design report, including plans and specifications for removing four waste rock piles during the project’s first phase.
- Careful Cleanup Delineation: GeoEngineers’ data-gaps investigation saved money by distinguishing naturally occurring arsenic in soil and bedrock, adjusting the cleanup level to commonsense criteria and eliminating the need to remove excess natural material.
- Technology Improved Efficiency: GeoEngineers’ Technology Team developed a real-time app to track sampling at the site and allow instant collaboration with the city and Ecology. The app was available on desktop and mobile devices so that team members and client representatives could monitor construction progress and field sampling results from anywhere in real time, speeding up feedback and decision-making.
The Saddle Rock Regional Park Interim Remedial Action successfully repaired the damage from historical mining without damaging or removing the naturally occurring features that make the park unique. The project also pioneered a new integrated approach for abandoned mine assessment and reclamation at sites within areas of variable and complex surficial mineralization for Ecology that is becoming a new standard for projects of this type.