Update on Acton Extension Application

Transcription

1 Update on Acton Extension Application Andrea Bourrie Property & Resource Manager, Dufferin Aggregates Dufferin Aggregates Acton Quarry Public Information Centre October 26, 2009 A division of Holcim (Canada) Inc.

2 Status of Acton Quarry Application Application was made on March 19/09. The Joint Agency Review Team (JART) process is in progress. The originally scheduled timeline for the JART review and final report preparation is approximately 24 months from the submission date. JART Peer Review comments are underway. A status report is expected this fall. 2

3 Status of Acton Quarry Application Along with the information exchange with JART, there is the need to have meetings in order to work through the issues. A Site Meeting/Walk was held on June 10/09. Members of the JART team and their peer reviewers visited the site and walked the proposed extension lands with representatives from DFA and our technical consultants. Sub-committee meetings are also being organized to allow the professionals in various disciplines to maximize their review/comment effectiveness. 3

4 Open House at the Acton Quarry On Sept. 12/09 Acton Quarry opened its doors to the public and held its annual Open House. There were various informational displays, including one that spoke to the status of the extension application. Activities included; site tours, rides on rock haul trucks, heavy equipment displays, raffle/door prizes, buffet breakfast and speeches. 4

5 Understanding Blast Effects Andrew Curic Golder Associates Dufferin Aggregates Acton Quarry Public Information Centre October 26, 2009 A division of Holcim (Canada) Inc.

6 What are the principal influences determining peak ground vibrations and air concussion at a receptor? Distance between the blast and the receptor (building) Maximum explosive weight per delay period 6

7 Acton Quarry Blast Design Details Hole Diameter = 114 & 127mm Max Face Height = 25 m Drill Pattern = x 4.7 m Approx. explosive weight per hole = kg Holes per blast = Approx. explosive wt per blast 5,000 18,000 kg Powder Factor = kg/cu.m. Blast Design 7

8 What Happens When an Explosive Detonates? Shock wave and gas are two basic forms of energy produced. Shock wave fractures rock. Each explosive charge produces its own stress wave. Stress wave travels through the ground at about m/s. Gas energy moves the rock forward (air concussion). Air concussion moves through air at speed of sound, 343 m/s. 8

9 Ground Vibration Characteristics Consist of surface and body waves; surface waves are typically felt by homeowners. Both waves diminish with distance from the blast due to dissipation of energy and reduction of sound levels as they radiate from the point source An individual s perception is dependent upon: Magnitude (relative size or extent) Dominant Frequencies Duration (length of time) 9

10 Summary of Several Provincial/State Ground Vibration Limits Ground Vibration Limit (mm/s) Rhode Island Ontario (mines and quarries) Alabama* Illinois* Indiana* Iowa* Louisiana* Maryland* Massachusetts* Montana* New Jersey* New Mexico* Ohio* Pennsylvania* (coal) Tennessee* (coal) Utah* Virginia* West Virginia* Wyoming* Arkansas Minnesota North Carolina North Dakota Oklahoma South Carolina Georgia Kentucky Maine New Hampshire Ontario (construction) Pennsylvania Tennessee * Generally uses OSM frequency based limits ranging from 19 to 31 mm/s. States not listed probably do not have any regulations limiting ground vibrations from blasting operations. Ontario regulations are some of the strictest in North America 10

11 Typical Measures of Ground Vibrations Peak Particle Velocity (in/s) (mm/s) Ground Vibration Effect Micro-cracks start developing in rock mm/s, limit often set for concrete Cracks start developing in plaster 50 mm/s, Ontario limit for construction blasting (different from Quarry blasting) mm/s, OSM frequency dependent limit 12.5 mm/s, Ontario limit for surface mines/quarries 3 5 mm/s maximum levels recorded around Acton Quarry mm/s, ground vibrations become perceptible 11

12 An Airblast Disturbance, along with Ground Vibrations, can be another undesirable disturbance resulting from Blasting Sources of Airblast are as follows: Ejection of stemming Escape of gases Displacement of rock face Displacement around borehole Expansion of unconfined explosives Ground vibration 12

13 Characteristics of Airblast Holes rifling (blowing out stemming) Quarry Blast 13 A division of Holcim (Canada) Inc. Application Update & Blasting Presentation Acton Quarry October 26, 2009

14 Characteristics of Airblast Face blowing out Produces air-blast Coal Overburden Blast 14

15 Sources of Airblast Stemming Ejection during Pre-Shear Blast 15

16 Atmospheric Conditions do not increase or decrease the air concussion energy from a blast, they only influence its distribution within the air. We may actually feel the blast more however there is no actual change in the energy it creates. Ideal situation Second desirable condition Avoid if possible Most unfavourable Most unfavourable Effects of Atmospheric Conditions 16

17 Typical Results of Air Vibrations Overpressure (dbl) (psi) Air Blast Effect Conventional structures can be severely damaged. Most Windows break (170 dbl) Some windows break (150 dbl). Some large, poorly set plate glass windows may break/crack dbl, USBM interim limit of allowable air blast. 128 dbl, Lowest Ontario limit. Threshold of complaints (117 dbl) Dishes & windows may rattle 17

18 Summary of Several Provincial/State Air Vibration Limits Air Vibration Limit (dbl) * * 130 North Carolina Ontario (mines and quarries) Kentucky Oklahoma * Based on frequency response of measuring instrumentation. Arkansas Illinois Indiana Iowa Massachusetts Ohio Pennsylvania Rhode Island Tennessee Utah Virginia Minnesota New Jersey Ontario regulations are some of the strictest in North America 18

19 What do the Air Concussion Levels Mean? Air Concussion Pressure Wind Gust 95 dbl psi 5 km/hr 100 dbl psi 6.5 km/hr 110 dbl psi 11 km/hr 120 dbl psi 20 km/hr 128 dbl psi 32 km/hr 134 dbl psi 45 km/hr In general terms, for every 6 dbl increase, the pressure doubles. 19

20 Responding to Comments made at Acton Quarry since the May 5 th Public Meeting Rob McDougall Site Manager, Dufferin Aggregates Dufferin Aggregates Acton Quarry Public Information Centre October 26, 2009 A division of Holcim (Canada) Inc.

21 We listened to your concerns and developed a multi-discipline team to look into potential opportunities for reducing impacts The team was made up of members of DFA operations and property, Orica (blasting), Tri-City equipment (driller). We used a business management approach to problem solving; eliminates any potential pre-conceived notions about the issue. We started from scratch. In Acton, we continue to blast within Ministry Guidelines 21

22 Previous Blasting Techniques were reviewed in order to assess where improvements could be made. Analysis showed that vibration readings remained low; complaints seem to be arising from Air Concussion. Began to use red plugs and balls to ensure no stemming ejection Additional use of weather forecasts (to the best of our ability); try not to blast on days with heavy overcast Results seem to show an improvement. Final conclusions cannot be made until further testing is completed 22

23 Blasting patterns and design were examined to determine if there could be any improvements on Air Concussion factors Began to profile the blast face to ensure no face ejections. This ensures proper amount of burden in front of front row holes Found some of the drill holes not perfectly straight from using bore track machine, therefore we worked with driller to correct this problem and achieve improved results We increased the amount of stemming from 8 to 10 feet. Additional cover has shown a reduction in vertical rifling (blasting out from drill hole) 23

24 What are the next steps? Continuing to bore track holes and correct any that have more than 15% deviation Continue to use feedback from residents to ensure we are on the right track Encourage residents to continue the lines of communication, both positive and negative feedback Challenge ourselves to improve on our already high practice standards 24

25 Thank you We would like to thank you for taking time out of your schedule to meet with us this evening. Q & A Time for your questions 25

26 A division of Holcim (Canada) Inc. Application Update HGRS_Master & Blasting Presentation Acton Quarry October 18/11/ ,