HomeMy WebLinkAboutNotes, Work PLANNER 7/27/2004
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Mem~ to File
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Date: July 27, 2004
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To: ZON2004-00006 (MTGATE QUARRY FILE)
From: Jim Donovan, DSD Planner II
Subject: July 22, 2004 Blast #3 & 4 Field report
In attendance for the Cityat Blasts 3 & 4 were myself, Deputy Fire Marshall Joe Wicks,
PW Inspectors Ron Sather & Billy Curtiss., The blasts were done "back to back" with
mill i-second delay. The work was perfonned in accordance with the Discretionary Use
Approval, the approved blasting plan, state and federal regulations and information
compiled from monitoring of Blasts I & 2.
Field conditions were 90 degrees with clear skies. On hand for the developers were Mike
Evans, Project Manager for the owner, Kris Jeremiah and Shaun Rimmington as co-
Blaster in Charge for BJ Equipment, blasting contractors. Excavation and grading of the
pond and wetland areas for the drilling and blasting crews continues, albeit slowly due to
limited stock pile and fill opportunities. Drilling rigs and excavators were removed for
the blast at approximately 3:30 pm. Presc~bed notice and security measures were
followed as per the blasting plan. Seismic and air pressure monitors were re-set to
calculate the impacts ofa "back to back" shoot. The 911 call center and City Hall were
notified of the impending work. '
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Blast 3 was located just south of Blast 2 in the center portion of the pond area and Blast 4
was to the west, approximately 30 yards, in the same pond area. Blast 3 had no exposed
face due to the rubble pile of Blast 2, which was still intact. Blast 4 was located at the
exposed west edge of the pond pit facing north to the quarry walls. A matrix of 208
vertical holes were drilled and loaded as per previous observations for Blast 3. An
additional 144 holes were laid out for Blast 4. Electronic detonation and filming was
performed from above the west wall over the blast site. Deputy Fire Marshall Joe Wicks
filmed the blast for the City. The intent was to fracture approximately 5500 cubic yards of
material in the sequential blasts.
At 3:45 Mike Evans and City staff moved southeast toward the Weyerhaeuser earthen
berm observation point. The h'TOUP had direct line of sight to the blast' area and waited
until 3:55. Five slow horn blasts were sounded 5 minutes before the blast; a radio check
indicated all preparations were complete. At I minute prior to blast, 5 rapid horns were
sounded and another radio check occurred. The final 10 seconds were counted down,
FIRE IN THE HOLE was announced and:the blast was triggered at 4 pm.. The blast was'
extended in duration relative to previous blasts, but had no noticeable increase in noise
level. More dust was observed than in prerious blasts due to drier conditions. The dust
dissipated relatively quickly, despite still ~ir conditions. Physical response of the rock
was similar to previous blasts, (surface raised 4-6 feet and slumped in place, no fly rock
observed). I .
After "All Clear" visual inspection revealed rock piled almost in place. All charges had
detonated and the test had gone exactly aJ planned. Initiiil read out from the nearest
residential monitors indicated that noise rbached a 100 decibel spike and seismic
disturbance was limited to approximatelyll 0-15% of the tolerable levels. Full analysis of
all monitor data for Blasts 3 & 4 will be incorporated in future blasts and reports. Staff
noted with Mike Evans that no reports ha~e been received from the contractors.
I Date Received: 7- L 1- O~
Planner: YvlQ..<.1..LD '1-8 fiLL
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