5. Blasting chambers
An operator must ensure that a blasting chamber ¾
(a) is completely sealed; or
(b) is fitted with a mechanical ventilation and dust extraction system which is operating so that ¾
(i) no visible dust escapes from the blasting chamber;
(ii) all air from the blasting chamber passes through the ventilation and dust extraction system before being discharged into the environment; and
(iii) air discharged into the environment does not contain any visible dust or more than 50 milligrams of particulate matter per cubic metre.
(2) If the ventilation and dust extraction system for a blasting chamber includes a wet scrubber the operator must ensure that ¾
(a) waste water from the scrubber is drained into, and contained in, settling tanks or ponds until all particulate matter has settled out; and
(b) the settling ponds or tanks are emptied as often as necessary to ensure their efficient operation.