The U.S. Environmental Protection Agency has concluded its cleanup of the site of a Clinton Township smoke supply shop that was destroyed in a massive explosion that killed one person, according to federal officials.

Work crews finished their activities Dec. 3 and left the former Goo Smoke Shop/Select Distributors Warehouse property along 15 Mile Road and Groesbeck Highway on Dec. 13.

Investigators still haven’t determined what started the March 4 fire and series of explosions at the facility, which sent debris including 10- to 15-pound metal cannisters flying through the air for miles.

The cleanup cost of $1.6 million came in about $900,000 below preliminary estimates. It took about 100 days to complete.

“The number of exploded compressed gas cylinders (based on visual cleanup) is hard to quantify but safe to say in the thousands,” EPA officials said in an update on their website.

The agency said it has dismantled and removed items brought in for the cleanup operation, including work trailers, fencing, construction equipment, technicians and security personnel.

According to the EPA, the cleanup work included final disposal of waste materials to an EPA-approved facility.

In total, about 28,300 aluminum and steel nitrous oxide (N20) compressed gas cylinders intact and fire damaged were degassed, devalved and recycled by the EPA.

Hundreds of thousands cans of ultra refined butane were identified during the cleanup strewn throughout and co-mingled with explosion debris, in addition to pallets of cans underneath layers of debris. Hundreds of intact cans of butane were identified, secured, and properly disposed throughout the cleanup process.

Having the ultra refined butane, which is flammable, in the same storage area as approximately 30,000 nitrous oxide cylinders is dangerous, as evidenced by the explosion, officials said.

“There are definitely statutes and rules and codes to avoid all this, but unfortunately, it would appear that the responsible party had a disregard to a lot of the information that could have prevented this,” Sean Kane, an on-scene coordinator for EPA Region 5, told The Detroit News.

According to Kane, the items “should never have them in the same proximity, because this is what can happen.”

Noor Kestou, 32, the owner of the Goo Smoke Shop, has been charged with involuntary manslaughter for the death of Turner Salter, 19, who was hit in the head by flying debris. A probable cause conference for the case is scheduled for Jan. 27 in 41B District Court.

Clinton Township Supervisor Paul Gieleghem said Thursday night that the future use of the property can’t yet be determined given the prospect of future civil litigation or whether the EPA might issue a lien on the land.

“We want to let the dust settle on all of the potential lawsuits,” he said. “The most important thing that needs to happen right now is to let the Macomb County Prosecutor’s Office seek justice for the family and give them peace of mind for the tragedy they have suffered.”