HomeMy WebLinkAboutNotes, Work PLANNER 7/27/2004 (2)
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Subject: July 15, 2004 Blast #2 Field e~ort
Deputy Fire Marshall Joe Wicks, State Deputy Fire Marshall Kristina Deschaine and I
attended the second blast at the MountainGate quarry site. The work was performed in
accordance with the Discretionary Use Approval, the approved blasting plan, state and
federal regulations and the monitoring results of the initial test blast (See July 12,2004
Melno). :
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Field conditions were 85 de!,'fees with clear skies and a slight breeze from the southwest.
On hand for the developers were Mike Ev~ns, Project Manager for the owner, Kris
Jeremiah as site superintendent and Shaun:Rimmington as co-Blaster in Charge for BJ
Equipment, blasting contractors. Site preparation included the excavation and further
stockpiling of rock at the protective berm ~long the south side of the pond site.
Excavation and some build up of rock had 'also been performed along the south side of
the future wetland mitigation site, approxit}1ately 30 yards north of the weyerhaeuser
Road and the subject site's south property line. Prescribed notice and security measures
were followed as per Test Blast I. Seismic: and air pressure monitors were re-set to
calculate the accuracy of anticipated impacts. The 911 call center was notified of the
impending work.' 1
Kris Jeremiah gave a brief overview of thel blast preparations. The blast area was lo'cated
just east of the test blast site (Blast #1), in the west central portion of the pond bench. The
area has an exposed face to the north, facirlg the main quarry wall. A matrix of
approximately 180 vertical holes were drilled and loaded. The 14-20 foot deep holes were
loaded with 2" diameter unigel stick dynamite, reduced to 1.5 inch diameter near the top
and stemmed or capped with aggregate to ~educe noise. Electronic detonation and filming
was planned from above the west wall over the blast site. The intent was to fracture
approximately 3000 cubic yards of material.
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At I :15 Mike Evans and fire personnel mo'ved southeast toward the Weyerhaeuser
emihen berm observation point. I proceeded to the north property line of a Golden
Terrace Subdivision property and stood ag~inst the back fence. My position was at the
same approximate ground level as the blast; however the 2 aforementioned benns, trees
and the Weyerhaeuser Road bank interrup'~ed my direct line of sight to the blast area. I
could see the upper quarry walls and the d~tonation point.
Five slow hom blasts were sounded 5 minhtes before the blast; a radio check indicated all
preparations were corriplete. At I minute Jrior to blast, 5 rapid homs were sounded and
another radio check occurred. The final 1 oj seconds were counted down, FIRE IN THE
HOLE was announced and the blast was triggered at I :25 pm. The other observers
reported that the surface raised 4-6 feet and slumped in place with minimal dust and
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roughly the same low "humph" sound as Blast # I.
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From my position at the residential property the blast noise was substantially muffled by
the mass of the earthen benns and the rece~sed location of the blast site. I experienced no
noticeable air pressure or ground disturbal1ce at my position. One neighborhood dog
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barked at the blast but it should be noted that the dog also barked as I walked the
Weyerhaeuser Road to my observation poillt. No comments or calls were received from
the neighborhood. A minor dust cloud dissipated quickly to the north.
After an "All Clear" from the blaster, visual inspection revealed a pile of rock in varying
sizes up to approximately 1.5 cubic yards. All charges had detonated and the test had
gone exactly as planned. Initial read out from the nearest monitor (SUB water tank)
indicated that seismic disturbance was limited to approximately] 0-15% of the tolerable
levels, consistent with the test blast. (It is noted here that the intensity of Blast # 1 was
over-estimated in the field and was lowered after analysis to approximately 10%.) Full
analysis of all monitor data for Blast #2 will be incorporated in future blasts and reports.
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