The Deschutes County Demolition landfill is not permitted as, and is not known to contain “toxic” or hazardous waste. The Oregon Department of Environmental Quality classifies the landfill as a construction and demolition debris landfill, and not as a hazardous materials site.
Multiple rounds of sampling and testing have been performed on the landfill waste and none have indicated the presence of hazardous or toxic material. Given the age of the landfill, it could contain some waste that was not authorized. Because that possibility cannot be ruled out through testing, it was considered as a factor in the development of the remediation plan, as well as cost scenarios.
No, in fact, when OSU-Cascades remediates the landfill, it will improve conditions of the landfill. Environmental engineers hired by OSU-Cascades categorized areas of the landfill as three “cells” based on age, use and fill materials. Waste from cells 1 and 2 are proposed to be fully removed, sorted, and processed. Cells 1 and 2 would be developable, and would mitigate, if not entirely eliminate concerns related to the potential for methane gas migration, groundwater contamination, and similar issues in those cells.
There are numerous methods for controlling dust during construction. OSU-Cascades contracted with expert consultants to develop plans for air quality monitoring and air quality management during construction. In addition, contractors are required to employ acceptable air quality and dust control practices during remediation and construction.
A small portion of the waste in cell 1 is suspected to be undergoing pyrolysis, creating settlement risk. As part of the proposed remediation plan, this waste material would be completely removed, eliminating any risk and creating developable land. In fact, the Oregon Department of Environmental Quality has confirmed that this area can be removed from the solid waste permit boundary once remediated. Without waste in cell 1, development restrictions will be lifted by DEQ and long-term monitoring will no longer be required, creating a benefit for the greater community.
Engineers found a geologic fault line that crosses the pumice mine property, roughly north to south, which likely extends into the landfill. This is part of the Metolius fault zone, characterized by the United State Geological Survey as a relatively low activity fault zone, with an assigned slip rate less than 0.2 mm per year. In terms of seismic activity, or potential, this site is no different from many other sites throughout Bend. What is unique about this site is the ability to readily identify the location of the fault and take necessary precautions during site planning. As an example, buildings would not be constructed on top of or across the fault.
Geotechnical engineers have identified measures to address site slopes. Civil engineers reviewed the site for access, mass grading, storm drainage and utilities.
The landfill remediation plan includes reuse of the landfill material after excavation, sorting, and screening. The screened fines will be blended with native soil, harvested on-site, and reused as backfill on the site. Studies conducted on the landfill indicate that the amount of material available on-site will be enough to grade the full site without importing large amounts.