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`P�,If0RN�9 California Ground Water Association o • 1017 L Street, PMB #312 • Sacramento, CA 95814 • GyaWATE�'� 1. Multiple detonations on deep wells create a new problem in the abandonment process. After initial detonation,it is possible for native material to mix with the sealing material causing the sealing material level to be higher in the well than anticipated.Multiple detonations can result in sections of the well casing not being perforated.This method should be avoided. VI. Down Hole Charge Control and Placement Methods: a. There are two methods of charge placement that are acceptable: i. Weighted charge lines: 1. Using a weight at the bottom of the charge line to anchor the shot in the bottom of the well. This method is most commonly used in the industry. Tremie pipe should be left 5 to 10 feet off the bottom of the well prior to sealing material placement to anchor the weight. ii. PVC Control Pipe: 1. This method requires PVC pipe,usually 1 inch in diameter,to be glued or threaded together and set in the well to total depth. The charge is attached to this line as it is being lowered into the well. This method gives positive control of the charge line as sealing material is being pumped to the surface. This method is not accepted in some Counties in California due to the remnants of PVC left behind after the detonation. iii. A charge line should never be attached to the same pipe used to convey sealing material into the well. If the Tremie pipe becomes compromised, the charge line will also become compromised. Example:Tremie pipe becomes plugged and must be extracted,the charge will also be extracted. b. Tremie pipe should be placed prior to installation of charge line. After pumping has begun and charges are anchored,tremie pipe can be removed as necessary until sealing material has reached the surface. c. Surface containment: i. A proper blast design should have no surface activity;however this is not always under the blasters control. In most situations, surface containment is not necessary,the Blaster in Charge makes the final decision to contain potential surface splash or to distance personnel and equipment from the splash. ii. If surface containment of potential sealing material splash is decided. Several options are available, such as front loader buckets,backhoe buckets, plywood tents,tarps,plastic sheeting. In any situation,the containment device should either be large enough to not become a projectile,or light enough to not be a danger if it becomes a projectile. AUTHOR TYLOR MCMILLAN