Rock characterization, blasting, and vibration control program in southwest Florida

The presence of a mobile home park with drinking water wells created a unique geoenvironmental deterrent to the developer's plans for effective rock blasting, excavation, and development of water management areas (lakes) in connection with the construction of Crown Colony Resort, a residential cum golf course community in southwest Fort Myers, Lee County, Florida, USA. Possibility of damaging vibrations from rock blasting operations and potential impact to the residential structures as well as integrity of the water supply wells required safety measures to be taken in developing the rock blasting program to alleviate concerns of county representatives. A properly planned program consisted of rock corings and geophysical characterization of site-specific limestone as well as simulated test blasts conducted in the farthest water management area in an effort to develop some site specific baseline parameters. Resultant Peak Particle Velocity, Particle Displacement, and Peak Particle Acceleration (RPPV, PD, and PPA) was measured at various stations placed at selected distances from the test blast areas. Measurements were taken and used in a comprehensive monitoring plan to address the county's concerns. The data so developed was presented and reviewed by the county, prior to the issuance of a permit for blasting for a limiting RPPV of 0.5 ips as per the county's blasting ordinance. Following completion of the investigative program and issuance of restrictive permit, production rock blasting operations were performed under the full-time monitoring of the geotechnical consultant. This included setting up of multiple monitoring stations at various locations, including selected locations near the mobile home park property. Additional items included documenting the contractor's drill hole patterns, quantity of explosives detonated in a given shot sequence and millisecond delay period, monitoring station distance, and RPPV at the surface level. Pre-and post-blast survey of structures within the critical influence zone were also conducted. This engineered, inspected, and tested program alleviated the county's concerns and provided a cost-effective method for rock blasting, excavation, and construction of these urban area lakes. More importantly, the test and production blasting operation and vibration (velocity, acceleration, and displacement) measurements provided noteworthy evaluations for close proximity development blasting near subterranean structures.