SUBSURFACE LANDFILL FIRE
SUPPRESSION AND MONITORING
A Case Study at the Campbell
Mountain Landfill, Penticton, British Columbia
Phase
1 Construction.
As mentioned previously, Phase 1 consisted of the installation
of an impervious clay cap over the landfill crest in conjunction
with shotcrete seals along the fractured bedrock found at the
edges of the ravine. Phase 1 was constructed by Kedon Waste Services
Ltd. of Penticton, with shotcrete work being subcontracted to
Silver Springs Ventures Ltd. of Kelowna, B.C. Phase 1 was completed
in May 1998.
In order to achieve
a shotcrete seal that would be effective in preventing air from
entering the North Ravine through the fractured bedrock, a shotcrete
seal was applied over a three metre width; the bottom of the seal
was one metre below the existing ground level elevation while
the top was one metre above the final clay cap elevation. The
first step was therefore to excavate a one metre deep by two metre
wide trench along the edges of the ravine to gain access to the
entire area of coverage.
The bedrock was thoroughly
cleaned using a high pressure air gun and or water gun prior to
the shotcrete being installed. The shotcrete itself consisted
of Type 50 cement, water, fine aggregate, a quick curing admix
and fibre reinforcing.
After the shotcrete
was given sufficient time to cure, the excavated areas were backfilled
using local till, and then the clay was installed. Once the clay
cap was in place, protective 15.2 cm square steel monuments with
lockable lids were installed over each of the monitoring wells
and the Thermistor strings were permanently installed in the appropriate
wells.
Because a membrane
cap was being contemplated directly over the clay cap, if the
clay did not achieve the desired seal (Phase 2), the original
plan was to hold off on applying the final biosolids cover. By
mid summer however, desiccation of the clay cap was noted due
to the extremely hot temperatures encountered during the summer
f 1998, and it was recommended that the final cover be installed
more as an insulation barrier than a vegetative cover.
next page
phase 1 monitoring results
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