Las Virgenes Municipal Water District
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Blasting Results
(Updated May 7, 2014)
Below are the results of the blasting seismograph and dam seepage monitoring. The information will be updated as new data becomes available. On some days there may be no blasting or just one blast.
Seismograph Monitoring
The Division of Safety of Dams (DSOD) requires that the peak particle velocity (PPV) or intensity of the blasting is limited to 2 inches per second at the dams (S-01 & S-02). Additionally, at the nearest homes, the PPV is limited to 0.5 inches per second, the level at which cracking of plaster or drywall might occur. NT or “not triggered” means that the PPV is below the 0.05 inches per second detection limit of the seismograph.
Click here for the location of the seismographs (PDF - 170KB).
Seismograph Monitoring Table (click on Blast ID to watch a video of the blast)
Seismograph Monitoring, Peak Particle Velocity (in/sec) | ||||||||
Blast ID | Date | Time | S-01 | S-02 | S-03 | S-04 | S-05 | S-06 |
T1 | 4/21/2014 | 12:28 | NT | NT | NT | NT | NT | NT |
T2 | 4/21/2014 | 13:30 | NT | 0.095 | NT | NT | NT | NT |
PS-1 | 4/22/2014 | 14:25 | NT | NT | NT | NT | NT | NT |
PS-2 | 4/23/2014 | 15:07 | 0.078 | NT | NT | 0.084 | NT | NT |
PS-3 | 4/24/2014 | 13:04 | 0.075 | NT | NT | 0.076 | NT | NT |
TEX-1 | 5/05/2014 | 13:35 | NT | NT | NT | NT | NT | NT |
TEX-2 | 5/07/2014 | 12:32 | 0.077 | NT | NT | 0.09 | NT | NT |
TEX-3 | 5/09/2014 | 15:36 | 0.073 | NT | NT | 0.081 | NT | NT |
TEX-4 | 5/16/2014 | 13:56 | 0.164 | NT | NT | 0.102 | NT | NT |
TEX-7 | 5/19/2014 | 12:50 | 0.069 | NT | NT | 0.062 | NT | NT |
TEX-5 | 5/20/2014 | 14:41 | 0.138 | NT | NT | 0.147 | 0.073 | NT |
TEX-6 | 5/22/2014 | 12:20 | NT | NT | NT | 0.058 | NT | NT |
TEX-8 | 5/27/2014 | 14:41 | 0.114 | NT | NT | 0.064 | NT | NT |
TEX-11 | 5/28/2014 | 14:24 | 0.082 | NT | NT | 0.081 | 0.064 | NT |
TEX-9 | 5/30/2014 | 14:33 | 0.096 | NT | NT | 0.074 | NT | NT |
TEX-13 | 6/02/2014 | 13:15 | 0.098 | NT | NT | 0.012 | NT | NT |
TEX-10 | 6/04/2014 | 14:10 | NT | NT | NT | NT | NT | NT |
TEX-12 | 6/05/2014 | 11:57 | 0.08 | NT | NT | 0.119 | 0.07 | NT |
* Blast ID designations are not sequential; they identify specific blasts that were pre-planned for the site.
Dam Seepage Monitoring
The DSOD also requires that dam seepage monitoring is performed daily, before and after blasting activities. Seepage is normal; all dams have some seepage as the impounded water seeks paths of least resistance through the dam and its foundation. Seepage only becomes a concern if it is carrying material with it. During monitoring, the clarity of the water is observed and the rate of flow is measured.
Click on the map for seepage monitoring locations (PDF - 874KB).
Seepage Monitoring Table
Location | |||||||||
Saddle | Easterly | Perch | Main | ||||||
Date | Time | Flow (gpm) | Condition | Flow (gpm) | Condition | Flow (gpm) | Condition | Flow (gpm) | Condition |
4/21/2014 | 6:50 | 2.22 | Clear | 0.25 | Clear | 0.92 | Clear | 3.00 | Clear |
4/21/2014 | 15:55 | 2.20 | Clear | 0.26 | Clear | 0.90 | Clear | 2.87 | Clear |
4/22/2014 | 14:50 | 2.29 | Clear | 0.25 | Clear | 0.91 | Clear | 2.84 | Clear |
4/23/2014 | 15:15 | 2.28 | Clear | 0.24 | Clear | 0.88 | Clear | 2.83 | Clear |
4/24/2014 | 13:15 | 2.28 | Clear | 0.24 | Clear | 0.87 | Clear | 2.87 | Clear |
5/05/2014 | 13:35 | 2.28 | Clear | 0.18 | Clear | 0.83 | Clear | 2.91 | Clear |
5/07/2014 | 13:05 | 2.28 | Clear | 0.18 | Clear | 0.85 | Clear | 3.75 | Clear |
5/09/2014 | 15:40 | 2.26 | Clear | 0.19 | Clear | 0.85 | Clear | 5.25 | Clear |
5/16/2014 | 14:15 | 2.39 | Clear | 0.13 | Clear | 0.91 | Clear | 2.82 | Clear |
5/19/2014 | 12:50 | 2.33 | Clear | 0.13 | Clear | 0.89 | Clear | 2.94 | Clear |
5/20/2014 | 14:50 | 2.34 | Clear | 0.13 | Clear | 0.89 | Clear | 2.91 | Clear |
5/22/2014 | 12:40 | 2.25 | Clear | 0.16 | Clear | 0.79 | Clear | 2.90 | Clear |
5/27/2014 | 15:00 | 2.14 | Clear | 0.12 | Clear | 0.88 | Clear | 2.90 | Clear |
5/28/2014 | 14:40 | 2.18 | Clear | 0.12 | Clear | 0.87 | Clear | 2.83 | Clear |
5/30/2014 | 14:45 | 2.20 | Clear | 0.12 | Clear | 0.86 | Clear | 2.94 | Clear |
6/02/2014 | 13:15 | 2.29 | Clear | 0.11 | Clear | 0.84 | Clear | 2.79 | Clear |
6/04/2014 | 13:00 | 2.19 | Clear | 0.10 | Clear | 0.84 | Clear | 2.90 | Clear |
6/05/2014 | 12:30 | 2.29 | Clear | 0.11 | Clear | 0.84 | Clear | 2.80 | Clear |