Downtown DeKalb’s Walgreens is making some changes to its parking lot. The drug store is fixing the big hole in it.

The sinkhole in the parking lot of Walgreens, 100 W. Lincoln Highway, has been filled since July, but it is only a surface indication of a larger problem.

John Lies, president of the Arnold Lies Company and landlord of the land Walgreens is built on, said the storm water drainage system that is located underneath the parking lot has failed. His company will repair the system.

There is no immediate danger of the parking lot collapsing, Lies said. The sinkhole is filled temporarily until repairs start.

Work on the sinkhole begins on Oct. 21, and will take about five days to complete, said Walgreens spokeswoman Carol Hizely.

The old system is made of plastic, and the new system will be made of concrete, Lies said.

The system is like an underground lake; it takes the place of an above-ground retention pond when space for it is unavailable.

“We don’t really know why it failed,” Lies said.

The system was in place before Arnold Lies purchased the lease on the building, Lies said.

Lies said the new concrete system will be stronger than the old plastic system.

However, he was unable to comment on how long it will take to complete the construction, once it begins.

Walgreens manager Marty Waugh said a pipe of the water drainage system failed and caused the large sink-hole to appear.

The City of DeKalb required that an underground storm water drainage system be built because there was not space available for an above ground system, Waugh said.

The former DeKalb Post Office, which was located on the property Walgreens now is located on, flooded a lot, Waugh said. That is why the water retention system was installed.