A woman signs the airport petition in front of an Edmonton grocery store on Monday. (CBC)The city of Edmonton expects it will cost about $100,000 to verify the names on a petition calling for a plebiscite on the future of the City Centre Airport.

"This is a very technical process. It is a time consuming process. It is not something we can afford to take shortcuts on," said Steve Thompson, the city's director of elections. "So, we will take the time that is necessary. It is possible that it could take the month."

Envision Edmonton, the group behind the plebiscite drive, is planning to deliver their petition to the city clerk around 3:30 p.m Thursday.

City elections employees will then have to go through the list to ensure the names belong to real people who live in Edmonton. The city will then use the services of a survey company to call some people at random to verify they signed the petition.

The $100,000 estimate comes from the cost of hiring this company as well as the wages of 15 to 20 temporary workers hired to help with the verification. The money will come out of the budget for October's municipal election.

Envision Edmonton board member Mary Ann Stanway said the cost of verifying the names is part of the process.

"We have a right to direct democracy. It's essential for our society and so therefore, this is the way the citizens' voices were heard, and then it's up to the city to follow through," she said.

Envision Edmonton needed to collect 78,244 valid signatures of Edmonton residents who are over the age of 18 and live in Edmonton. The number represents 10 per cent of the city's population.

The group says volunteers surpassed that number after holding a petition blitz on the weekend. The group is doing verification of its own before the petition is delivered to city hall.

An Envision Edmonton spokesperson told CBC News just before 7 p.m. Wednesday that the group had verified 89,000 signatures.

The city has 30 days to verify the petition.