We are having a blast building SR 823!
(lots of them actually)
Building SR 823 requires the movement of approximately 20 million cubic yards of earth. About half of that quantity will require some high velocity encouragement to help it move because it is rocky earthen material. The most economical and safest way to accomplish that movement is via the use of blasting.
How is it done?
First by drilling.
First a grid of holes spaced several feet apart from each other are drilled vertically into the rock. The number of holes in the grid will vary but there may be over one hundred. These holes vary in size and are generally between 2 inches and 6 inches in diameter and are drilled as deep as the excavation is intended to be.
Specially trained personnel insure that all work is done according to a detailed preplanned sequence and specification and these personnel are present at all times during every phase of the drilling and blasting procedures.
What is the next step?
Loading the charge.
This activity is carefully planned using the best technologies available
Specially formulated materials call blasting agent is then loaded into the holes, this is called charging. This blasting agent will not explode or detonate accidently. It is inherently harmless material and requires an additional activating ingredient to be applied to the charged holes after all the holes are filled and only after all required precautions have been taken to create the actual explosion or blast.
Prior to any blasting operations all access to the project is stopped, Special signs are deployed, warning horns are sounded on the project and this continues until the area is cleared to safely detonate the charge.
What triggers the blast?
A controlled detonation.
After the holes have been charged, a special set of materials are applied to each hole and these are all connected to a control unit that act chemically to activate the explosive forces that expand the rock very quickly to fracture and loosen the rock for subsequent movement by construction equipment.
The time that it takes the blast to occur is as little as a few seconds. The blast will be loud- think of thunder and a slight rumble under foot may be experienced. The project is off limits to the public except on public tour occasions and the proximity of the blasts to homes, businesses and the public is very limited.
How often will the blasting be done?
Almost every day.
The project will take many months to build and because the blasting is done in a controlled manner the safest way to perform the work is using small, regular and planned cycles. Typically the blasting will be performed during the noon hour, and at the end of regular work shifts around five 0'clock. Because the project is 16 miles long from end to end and there will be four segments under construction concurrently there may be several blasts in one day. Because the actual blast takes only seconds to experience the sound and feeling. Because the follow up earth hauling work takes many hours to move the blasted material this is a consistent operation and will be continuing through 2017.