(1) Whenever a seismograph is used to monitor the velocity of ground motion and the peak particle velocity limits of ARM 17.24.624(11) are not exceeded, the equation in ARM 17.24.624(14) need not be used. If that equation is not used by the operator, a seismograph record must be obtained for each shot.

(2) The use of a modified equation to determine maximum weight of explosives per delay for blasting operations at a particular site may be approved by the department, on receipt of a petition accompanied by reports including seismograph records of test blasting on the site. The department may not approve the use of a modified equation if the peak particle velocity for the limits specified in ARM 17.24.624(11) are exceeded, meeting a 95% statistical confidence level.

(3) The operator may use the ground vibration limits described in the blasting-level chart referenced in 30 CFR 816.67(d) (4) as an alternative to (1) and (2) , upon approval by the department.

(4) The department may require a seismograph record of any or all blasts and may specify the location at which the measurements are to be taken.