RAPID CITY, S.D. — Rapid City officials say the city's landfill could be full by 2037 — 16 years earlier than anticipated.

Wenck Associates, Inc., a Minnesota-based engineering firm, estimated in a 2016 report that the landfill would reach capacity in 2053, the Rapid City Journal reported. The landfill must renew its permit every five years and the report was conducted ahead of the landfill's application for renewal. It assumed the landfill would see an annual growth in collections of 1.7 percent.

The lost time equates to a loss of tens of millions of dollars, said former landfill superintendent Jerry Wright.

Public Works Director Dale Tech said that while the 2006 study was accurate when it was published, it was conducted before some cells in the landfill were designed and built, so the estimate has changed.

"It's all just based on estimates and was a snapshot in time," Tech said. "It was accurate the day it was published and every day beyond that things change."

Landfills are dynamic systems and a 12-year-old report isn't a good predictor, said Assistant Public Works Director Dan Coon.

"To say a report that's 12 years old was going to follow exactly in line, I don't know of any plans that we do that happen exactly like we think they're going to happen," Coon said. "The landfill life operation is a very dynamic system."

Coon said the landfill will likely try to adjust practices to extend capacity.

"If you come back at the end of 2019 and ask these same questions, we may say, 'Now we think we can go to 2040 because we've modified some of our practices,'" Coon said.