The art and science behind “Thunder Over La Porte City”

First in a Series by Mike Whittlesey

On the evening of Friday, June 14, thousands of people in and around La Porte City will look to the sky for an annual display of fireworks whose size and scope dwarfs those of similar-sized communities. “Thunder Over La Porte City” has been an annual tradition at the Festival of Trails Celebration for many years, thanks to Jim Robertson and the La Porte City Telephone Company, who, for many years served as the event’s sole sponsor before the La Porte City Lions Club and other generous donors helped fund the event. Since 2004, Mike Chingren, owner of Black Hawk Auto Refinishers, has served as the show’s lead operator, planning and presenting shows that have been presented at Union High School and La Porte City Elementary School.

Ever since 200 B.C. when the Chinese discovered that bamboo thrown into a fire creates a big bang, humans have been fascinated with fireworks. After traveling to the Orient in 1295, Marco Polo introduced fireworks to Europe. In turn, the early settlers of America brought fireworks to the New World in the 1730s. One hundred years later, Italians discovered that the addition of certain chemicals could produce vivid colors in their pyrotechnics. For example, yellow is made with the addition of sodium. Copper produces the color blue, Barium makes green and Strontium results in hues of red.

Fast forward another 200 years and the level of sophistication has continued to grow by leaps and bounds. Despite the many technological advances, however, fireworks remain a dangerous commodity. Because of this, for many years the state of Iowa had very restrictive laws related to the purchase and usage of fireworks. While some of those restrictions have loosened considerably for consumers recently, operators like Mike and Heather Chingren, who wish to produce fireworks displays such as the annual show presented during La Porte City’s Festival of Trails Celebration, must be properly certified before they can procure and handle the kinds of pyrotechnics that light up the sky and produce “Thunder Over La Porte City.” Such certification requires taking classes, passing an exam and completing successful internships assisting with the production of other shows before being allowed to serve as lead operator. Once obtained, certification must be renewed every three years.

It is the National Fire Protection Association (NFPA) that develops and revises the generally accepted industry standards for fireworks displays. These standards address three main areas:

NFPA 1123 – Code for Fireworks Display
NFPA 1124 – Code for the Manufacture, Transportation, Storage and Retail Sales of Fireworks and Pyrotechnic Articles
NFPA 1126 – Standard for Use of Pyrotechnics Before a Proximate Audience

In any fireworks display, the NFPA identifies four main players responsible for their safe presentation:

  • Operator and assistants
  • Authorities Having Jurisdictions (AHJs)
  • Sponsor(s)
  • Spectators

It is the operator who has the overall responsibility for the safety, setup and discharge of the display. That includes training assistants to perform their tasks and educating them about potential safety hazards. In the case of La Porte City’s show, that responsibility is handled by the Chingrens, who rely on a crew of experienced volunteers to assist with the setup on the day of the event. These volunteers share the same passion for pyrotechnics and many return year after year to assist with the setup, a process that takes many, many hours to configure.

When setting up a show, operators must abide by minimum separation distances spectators must be kept from the fireworks. They must ensure that the proper locations and methods for setting up the equipment and fireworks have been followed. In the days leading up to La Porte City’s fireworks display, the Chingrens will use caution tape and other barriers to rope off areas where spectators are not allowed. They also work with local police and the fire department to ensure adequate security and fire suppression systems are available, if needed. During the show, security personnel position themselves along the roped off area to remind spectators to maintain a safe distance.

Over the years, the Festival of Trails Celebration has had its share of weather-related challenges. Should the weather or other unforeseen event become an issue, it is the operator who is ultimately responsible for the decision to delay or postpone a display. It’s a decision the Chingrens take seriously, one where the safety of the spectators is the first priority. After spending a long day setting up the show and moving trailer loads of equipment into place, postponing the Festival of Trails fireworks, while not a popular decision, has happened on a couple of occasions in the 15 years the Chingrens have produced the show. The last time the event was rained out on the scheduled Friday night, the crew did their best to cover everything to preserve the setup for the next evening. With thousands of dollars of fireworks sitting in the surrounding fields, the Chingrens remained on site to secure the area, spending the night in the back of their Suburban to keep watch over the thousands of shells around them.

Like any industry, the world of fireworks has a language and terminology all its own. The science of pyrotechnics begins with the construction of a shell, the object that contains ingredients designed to produce a chemical reaction that will display a desired effect across the sky. The shape and composition of the shell also dictate the altitude (height) and amplitude (size) of the visual effect.

Fireworks contain six important ingredients:

  • Fuel – typically black powder (charcoal)
  • Oxidizing agents – produce the oxygen needed to burn
  • Reducing agents – burn oxygen to produce hot gasses
  • Regulators – used to control the speed of the reaction
  • Coloring agents – chemicals that produce color
  • Binders – used to hold the fireworks together


The explosion of a firework happens in two stages. First, the aerial shell is placed in a tube, which is called a mortar. When a fuse attached to the shell is lit, the black powder ignites, creating heat and gas beneath the shell, propelling it into the sky. Inside the shell, a time-delay fuse ignites, eventually causing a bursting charge to explode. This explosion produces hot gasses very quickly. As the temperature of the gas increases, so too does its volume, creating the necessary pressure to burst the shell. The loud boom that is heard when the shell explodes is produced by the expansion of gases at a rate that is faster than the speed of sound. When the shell explodes, the stars within it are expelled, producing a pattern in the sky that is determined by how they were packed into the shell when manufactured.


The Festival of Trails fireworks show utilizes many different types of fireworks, blending high-end, professional grade shells with lower cost, consumer-grade fireworks to create a variety of effects both on the ground and in the air. With a show that lasts up to 25 minutes in length, such a mix maximizes the number of fireworks that can be used, given budget restraints. Thanks to the necessary licensing possessed by the Chingrens, “Thunder Over La Porte City” utilizes fireworks purchased at wholesale pricing, which gives the show literally more bang for its buck. Donations of nearly $9,000 were received from the community to make this year’s show possible. 2019 sponsors include LPC Connect, Cedar Valley Bank and Trust, Pipho Family Dentristy, Jama Runyan and Brook Skram, CPA, Teresa Meyer of Farm Bureau Financial Services, Don Schmitz and Sons, Inc, American Legion Post #207, The City of La Porte City and Black Hawk Auto Refinishers. With more than $10,000 of fireworks purchased for the June 14 display, the Chingrens also make a personal financial investment in their hometown show that goes above and beyond the time and expertise they donate to produce it.

Next week: How do they do it? This year, as Mike and Heather Chingren prepare to shoot their 16th Festival of Trails Fireworks Display, the show will be completely choreographed to music for the first time ever.