ems Pimlico Flats, no. 5, Triq Viani, Sliema, MALTA Mob: +356 9944 5767 Email: tcini@yahoo.com environmental monitoring services BLAST MONITORING REPORT HG12 Hard Stone Quarry at Ta Klement, l/o Qala Gozo 1st March 2013 Details Date 01-03-2013 Quarry number HG12 Ta Klement, l/o Qala Gozo Quarry operator Ballut Blocks Ltd. ANFO Supplier Road Constructions Co. Ltd. Police escort PC1127 F Bonello Location and Time of Blasting Three blasts were carried out between 12:27 and 12:37 at the points as approximately indicated on the attached site diagram. Summary of Blasting Conditions Maximum charge per delay: 70-90m: 13Kg; 90-110m: 21Kg; 110-130m: 32Kg, 139-150m: 45Kg; 150m+: 60Kg. These distances are to be measured from the slipway and the girna. Vibration limit: 4 mm/s (20 to 40) at the nearest girna or the natural arch near the slipway. Air overpressure limit: 120 db(l). Site Specific Permit All holes were within quarry boundaries and within the maximum depth allowed. Maximum charge per delay was not exceeded. Blasting is carried out according to site specifications. Weather Conditions Humidity [1] Wind [1] Temperature [1] Cloud Cover [2] 69% 24 Knots SE by E 16 C c. 100% low cloud cover [1] As reported by weather.maltairport.com on 1 March 2013 at 12:15 at Luqa Airport [2] Our observation Comments All holes are at the top shelf of the quarry in their respective location. This blast was a trial of the new method of reducing the ANFO. In this trial the burden was reduced to 2.4m and the amount of ANFO per hole is reduced to 35Kg. The reason is that the quarry was called to follow the new vibration and air overpressure limits and this necessitates the reduction of maximum charge per delay. 2013-03-01_HG12 Report Page 1 of 2 Anthony Cini Digitally signed by
e m s environmental monitoring services Notes about Monitoring The seismograph was placed at the entrance to the girna. The seismograph was set to trigger at 0.51 mm/s. Instrument used is MiniMate Plus, serial number BE9488. Readings Blast Number 1 2 3 Time 12:27 12:32 12:37 No. of Holes 11 11 11 No. of Delays 11 11 11 Depth of Holes (m) 13.5 13.5 13.5 Max. Charge per Delay (kg) 35 33 33 Total Charge (kg) 375 363 363 Dist. from Seismograph (m) 170 170 170 PPV (mm/s) 1.13 2.17 1.81 Frequency () 57 46 29.3 Air Overpressure (db L) 118.8 146.2 133.1 Scaled Distance (m kg -½ ) 28.7 29.6 29.6 Burden is an average of 2.4 metres, and distance between holes is an average of 2.5 metres. Weights in kilograms are rounded-up to the nearest unit, and depth in metres is rounded to the nearest ½ unit. Displacement between holes and the seismograph is measured using the online version of MEPA s Map Server and is accurate to the nearest 10 metres. Number of holes, their depth, burden, and the amount of ANFO used are as given by the quarry operator. Scaled distance and maximum charge per delay are calculated from the primary data. Weights are rounded-up to the nearest kilogram and the depth is rounded to the nearest ½ meter. Observations There was no flyrock outside the quarry boundaries. No damage to the surroundings was observed after the blast. The air overpressure measured exceeds the 120dB limit by 26dB in one case and by 13dB in another case. The ground vibration is within the limits of 4mm/s. The reason for the excessive air overpressure is the reduced burden due to the gas-release pulse: that is the gases produced by the explosion escape through fissures in the material being cut with great force. The rock was cleanly cut and the quarry operators plan to further reduce the ANFO per delay and increase slightly the burden in the next blasting to address the air overpressure exceedances. Anthony Cini B.Sc. 2013-03-01_HG12 Report Page 2 of 2
Event Report Date/Time at 12:27:36 March 1, 2013 Trigger Source Geo: 0.510 mm/s, Mic: 119 db(l) Range Geo: 31.7 mm/s Record Time 2.0 sec at 4096 sps Notes Location: Quarry Blasting Client: User Name: ems General: Serial Number Battery Level Unit Calibration File Name 254 200 BE9488 V 8.01-8.0 MiniMate Plus 6.1 Volts September 3, 2012 by Datum Monitoring K488EP53.Y00 BS 6472:1992 CURVE 32 Microphone PSPL Channel Test PPV Time (Rel. to Trig) Peak Acceleration Peak Displacement Frequency Overswing Ratio Linear Weighting 118.8 db(l) at 0.654 sec 8.5 (Freq = 20.1 Amp = 542 mv) 0.905 16.9 0.139 464 0693 7.1 0.762 59 0.149 0765 7.5 3.7 1.13 57 05 663 0386 7.6 mm/s sec g mm Velocity (mm/s) 100 50 20 10 xy Peak Vector Sum 1.23 mm/s at 05 sec 5 z 2 1 1 2 5 10 20 50 100 > Frequency () : + : x : AirOP 1.0 2.0 Time Scale: 0.20 sec/div Amplitude Scale: Geo: 0.500 mm/s/div Mic: 10 pa.(l)/div Trigger = Printed: April 18, 2013 (V 10.40-10.40) Format 1995-2012 Xmark Corporation
Event Report Date/Time at 12:32:40 March 1, 2013 Trigger Source Geo: 0.510 mm/s, Mic: 119 db(l) Range Geo: 31.7 mm/s Record Time 2.0 sec at 4096 sps Notes Location: Quarry Blasting Client: User Name: ems General: Serial Number Battery Level Unit Calibration File Name 254 200 BE9488 V 8.01-8.0 MiniMate Plus 6.1 Volts September 3, 2012 by Datum Monitoring K488EP54.6G0 BS 6472:1992 CURVE 32 Microphone PSPL Channel Test PPV Time (Rel. to Trig) Peak Acceleration Peak Displacement Frequency Overswing Ratio Linear Weighting 146.2 db(l) at 0.669 sec 19.0 (Freq = 20.1 Amp = 542 mv) 0.905 55 60 0566 7.1 1.06 41 80 0620 7.5 3.7 2.17 46 10 729 0771 7.6 mm/s sec g mm Velocity (mm/s) 100 50 20 10 xy Peak Vector Sum 2.21 mm/s at 09 sec 5 z 2 1 x 1 2 5 10 20 50 100 Frequency () : + : x : > AirOP 1.0 2.0 Time Scale: 0.20 sec/div Amplitude Scale: Geo: 0.500 mm/s/div Mic: 10 pa.(l)/div Trigger = Printed: April 18, 2013 (V 10.40-10.40) Format 1995-2012 Xmark Corporation
Event Report Date/Time at 12:37:03 March 1, 2013 Trigger Source Geo: 0.510 mm/s, Mic: 119 db(l) Range Geo: 31.7 mm/s Record Time 2.0 sec at 4096 sps Notes Location: Quarry Blasting Client: User Name: ems General: Serial Number Battery Level Unit Calibration File Name 254 200 BE9488 V 8.01-8.0 MiniMate Plus 6.1 Volts September 3, 2012 by Datum Monitoring K488EP54.DR0 BS 6472:1992 CURVE 32 Microphone PSPL Channel Test PPV Time (Rel. to Trig) Peak Acceleration Peak Displacement Frequency Overswing Ratio Linear Weighting 133.1 db(l) at 0.696 sec 17.7 (Freq = 20.1 Amp = 542 mv) 0.857 24.4 81 331 0630 7.1 1.40 29.3 0.125 0738 7.5 3.7 1.81 29.3 0.111 530 0894 7.6 mm/s sec g mm Velocity (mm/s) 100 50 20 10 xy Peak Vector Sum 1.88 mm/s at 0.111 sec 5 z 2 x 1 x 1 2 5 10 20 50 100 > Frequency () : + : x : AirOP 1.0 2.0 Time Scale: 0.20 sec/div Amplitude Scale: Geo: 0.500 mm/s/div Mic: 2 pa.(l)/div Trigger = Printed: April 18, 2013 (V 10.40-10.40) Format 1995-2012 Xmark Corporation