Before clean up could begin, PHH ARC completed sampling for particulate and organic compounds to establish respiratory protection for the clean up crews. Once safe work practices had been established, restoration crews began dry ice blasting soot from the impacted concrete surfaces. Since the concrete surfaces would be covered by finishes in the occupied areas of the building, odor was the major concern for clean up. In order to minimize construction delays, we needed to find a way of predicting and measuring removal of fire damage so that persistent odors were diminished.

There were no established criteria for what constituted a “clean” or “dirty” surface, but the property insurance required that the building be restored to its pre-loss condition, We carried out parallel testing of soot contaminated surfaces by swab sampling for hydrocarbons and surface tape-lift particulate sampling to determine the most reliable and cost effective method of assessing contamination. Samples were collected from heavily contaminated surfaces and lightly contaminated surfaces. Control samples were collected from areas at sufficient distance to not have been impacted by smoke damage.

Hydrocarbon analysis did not prove to be a particularly useful indicator of potential contamination. Hydrocarbons were present in relatively low concentrations on heavily impacted surfaces in and adjacent to the parkade, but below detection limits on surfaces which visibly had some levels of smoke damage.

Particulate characterization was however a consistent and predictable indicator of damage and subsequent cleanliness. Heavily impacted surfaces showed soot and combustion particles as the major components of particles on the tape-lift samples, and lightly visually impacted surfaces had soot as either major components or minor components. Un-impacted and reference samples showed soot to be present in trace amounts or not at all.

These results suggested that trace levels of soot on a sample represented a “clean” surface whereas, major or minor levels represent a “dirty” surface. Based of the results of parallel analysis PHH ARC recommended that surface particulate sampling and comparison with benchmark soot levels would be a cost effective method of determining the effectiveness of cleaning surfaces.

The restoration contractor’s work crews performed the clean up over a four month period. The dry ice blasting process resulted in minimal debris and no damage to the parent structure. Surface sampling throughout this period verified the effectiveness of the cleaning methodology. The building was completed to the client’s satisfaction and the construction schedule was allowed to proceed with minimal delays.