Speculation on strength of the recent blast
Posted by Steven Hurdle on October 1, 2008
This first-hand account is from someone who professes to be associated with the blasting industry who has attempted to calculate the strength of the recent Savory Road blast (I prefer to refer to it by the residents that if affected rather than the mega-project it is for), pictures of which are here. I’m not a blasting professional and not able to verify the person’s calculations, but I list it here for people’s interest and for peer review (if we have any readers who have knowledge on the topic).
“I received Steve Hurdle’s “Langford News Update” this morning and read about an account of the blast which I also felt.
The size of the blast was the eqivalant of a 20 ton blast.
Calculation as follows – approximately 750 bags at 25 kg per bag (55 pounds for us grey haired people) of a product known as ANFO which is a mixture of Nitrate and Diesel fuel (remember the Oklahoma bombing with Timothy McVey?). 750 X 55 = 41,250 divided by 2000# per ton = +/- 20 tons
The product is detonated by placing individual sticks of dynamite at the bottom of each hole which an associate who works in the blasting industry estimated were possibly 40 +/-.
I have been scratching my head – but I can’t remember WHO stated, that with the professional blasting companies being employed, the karsts were in NO DANGER. With the size of yesterdays blast, I would find this to be extremely unlikely.
Cheers”
– Steven Hurdle -
Michael McCormick said
Re: Estimating Intensity of Blast:
1. To clarify the intensity of the Blast which occurred about 5:10PM Friday,26, 2008 above Savory Road concerned citizens can request a copy of the actual blast information which is called a “BLASTING LOG” which includes: date,time,location, blast number,hole diameter, hole depths,number of caps used, Burden & spacing, Face height, Type & amount of powder used, Type of cover used (ie rubber matts???)weather conditions, distance to nearest structure, number of series, Blasting machine, SEISMIC DATA including POST BLAST EFFECTS & RESULTS ending with blasters signature) from the Engineering Department,Langford City Hall, as a public service to the community. They will in turn request this “Blasting Log” from Western Grater Contracting Ltd who were the blasters at that location.City Hall has been very co-operative in this area in the past regarding assisting the public with concerns in this area of concern.
In the Spirit of being helpful,
Michael McCormick