Envirocon Successfully Completes Demolition of Historic Building

The Envirocon team recently completed a design/build demolition project in northwestern Oregon. Constructed in the late 1800s, the unstable building had been inactive since the 1970s. Due to historical significance, our team was able to achieve the client’s goal by removing the roof and walls down to the floor and maintaining the original foundation.

In September 2019, Envirocon mobilized management staff, limited craft personnel, and equipment. The project team worked closely with structural engineers and environmental consultants to provide a thorough review of the project site. The Hazardous Material Assessment results confirmed the presence of asbestos and lead contamination. Therefore, the field crew applied a lead boding agent to painted surfaces, stabilizing the lead at the molecular level and enabling material disposal at a Subtitle D landfill – and not as hazardous waste.

The Structural Assessment results identified several additional problems. Most significantly, the floor was degraded and structurally compromised. The project team determined a new floor would need to be constructed over the original floor to support man lifts and other equipment during demolition activities.

In January 2020, our team began the building’s demolition at the north end and progressed southward. To prevent premature collapse, they tied trusses together with structural lumber, steel cables, and shoring towers after removing the asbestos roofing and plank siding; roof removal then continued south in a bay-by-bay manner. After transporting roofing and trusses to roll-off containers, the team pulled temporary safety rails and the remaining pieces of wall columns. The team then installed OSHA compliant barricade. The Envirocon team demobilized from the site and successfully completed the project in February 2020.