We think past production and see our impact on the world.
An essential part of our civilization is the wide availability and distribution of inexpensive, high-quality stone. The most economical way to extract Wisconsin’s famously hard limestone is with explosives. This keeps costs down for every builder and supports our state’s infrastructure. If there were a more economical way to extract stone, the industry would immediately switch to that.
We take risks on new ideas, but not on safety.
Blasts in our quarries are designed by highly trained and skilled blasters who are certified by both the Mine Safety and Health Administration and the Wisconsin Department of Safety and Professional Services. The heavily regulated explosives used are generally safe to handle, and components are delivered separately to ensure safety over the road. Blasters place multiple seismographs and audio sensors near the closest residences and businesses to ensure that the ground vibrations and “airblast” are well below state limits.
Mining is our craft and our passion.
In the early days of quarrying, explosive placement was not done scientifically, although attempts were made to minimize cost and maximize output. High explosives were detonated instantaneously, causing ground vibration and “airblast” often felt by the whole neighboring community.
Today, instead of instantaneous detonation, explosives in each drill hole are initiated in a predetermined sequence so that there are delays of a few milliseconds between each activation. The shock waves generated direct much more energy into breaking the stone effectively (making the blast more economical) and less into air and ground vibration (making blasting less alarming for our neighbors).
Blasters create a detailed record of each blast, including the results of seismographic monitoring, and we maintain those blast records for years. The most important use of the records is to continually make blasting outcomes more predictable.
We work with, appreciate and learn from all people. New blasting research and techniques are coming out constantly. We attend industry conferences several times a year to learn about improving blast results from the experts. We love trying new approaches and are constantly experimenting to see if other methods used around the world may improve blasting outcomes for our miners and neighbors.
We appreciate feedback from our neighbors because we need more information about blast performance to continue improving our program. Blasters can often optimize the layout and timing of a blast to manage the impact that’s perceived by the community around the quarry, so every bit of feedback helps.
When a blast detonates, energy radiates in all directions as wave motion, like a ripple created in a lake when a stone hits the water. This wave travels mainly along the surface at 5,000 to 20,000 feet per second. Its energy level falls off rapidly with distance and is normally undetectable by most people beyond several thousand feet. Because explosives are expensive and vibration represents wasted energy, it is to the blaster’s advantage to minimize ground vibration.
Blasters control ground vibration by limiting the weight of explosives detonated within any 8-millisecond period of time. They use millisecond-delay detonators (blasting caps) to separate the firing time of each hole. A typical 50-hole blast, therefore, is actually 50 smaller, separate explosions.
When a blast is detonated, some energy is lost to the atmosphere as noise or concussion. This is caused by gases venting through cracks and the motion of rock on top and in front of blastholes. The resulting sudden increase in air pressure is called airblast. Like ground vibrations, airblast levels decrease rapidly with distance. However, airblast travels only at the speed of sound, about 1,100 feet per second, depending on air temperature, and can be greatly influenced by wind direction and speed. Atmospheric temperature inversions can also influence airblast by bending it back towards the earth and focusing its energy several miles away. Airblast is measured with a special microphone connected to a seismograph. The most common units of airblast measurement are pounds per square inch (PSI) and decibels (dB).
Airblast is controlled by placing stemming material (drill cuttings or crushed stone) above the explosives in the blasthole and by not loading explosives into parts of holes with cracks, voids or mud seams.
The United States Bureau of Mines conducted extensive research over a 35-year period and has published recommendations that limit blast-induced ground vibration and airblast to protect homes and other structures from damage. The Division of Mineral Resources has incorporated these recommendations into mining permits as special permit conditions for mines across the state.
Per Wisconsin Code SPS 307.44, an airblast may not exceed 133 peak dB at the location of any dwelling, public building or place of employment outside the controlled blasting site area. The blaster shall use the ground vibration limits specified below to determine the maximum allowable ground vibration.
Seismographs measure ground vibration in terms of particle velocity, which is the speed, in inches per second, at which ground particles oscillate as the wave passes. Beyond several thousand feet, ground movement is only a small fraction of an inch.
To give us feedback directly, or for a tour of operations, call our main office (262) 251-1520 and ask for Nate Swinton. Contact Charlene Vogt with the Wisconsin Department of Safety and Professional Services at Charlene.Vogt@wisconsin.gov for regulatory questions.
We smile more than we swear
We are generous teachers
We are all in this together
We take blame and share credit
We say thank-you for a job well done
We are honest and trustworthy
When we say, “I got this”, everyone knows it’s true
We are constantly learning new things
We treat our equipment as our livelihood
We are passionate about our craft
We take risks on new ideas, but not safety
We don’t stop with the repair, we redesign
We happen to things. Things don’t happen to us.
We are tougher than our circumstances
We find problems and solutions
We go home safe every day
We are attentive and considerate neighbors
We protect and care for the environment
We support and are involved in our local communities