BAM Ritchies

Case Study: Holme Park - Pre Splitting

Client: Aggregate Industries

Location: Kirkby Lonsdale

Date: 2005

BAM Ritchies, the specialist drilling and blasting and geotechnical division of BAM Nuttall Ltd., completed an important pre-split contract at Holme Park Quarry for Aggregate Industries.

The work was undertaken to protect areas of limestone pavement within the Farleton Knott Pavement Order from damage.

The method of work was planned as follows:

  1. A line defining the limit of excavation was accurately set out by a surveyor as agreed with English Nature and the Mineral Planning Authority.
  2. The overburden was stripped, with a full photographic record being maintained for inspection by English Nature and the Mineral Planning Authority. This was done in a way that ensured no damage to the limestone habitats.
  3. A series of closely spaced holes along the line of extraction were drilled, charged and detonated prior to the bulk charges in the excavation area. This ‘pre-split’ formed a fracture plane along the agreed extraction line and ensured that any disturbance to rock beyond the agreed line of extraction was minimal, while also guaranteeing the highest level of protection to the limestone habitats
  4. The design of the ‘pre-split’ and bulk charges was advised by BAM Ritchies to ensure that ’best-practice’ was observed at all times. During the drilling of all holes the drill rig was positioned to ensure that the tracks did not cross the agreed line of extraction.
  5. The amount of pre-split and bulk charges that were initiated took into account the relevant planning restrictions, safety considerations and ensured that noise nuisance was controlled at a reasonable level.
  6. The pre-split charges were detonated simultaneously prior to the bulk charges. The design of the hole diameter, inclination, burden, spacings, column charge, stemming and detonating sequence was planned and executed to provide optimum performance, minimal back-break and vibration and to ensure high levels of safety.