The Assiniboine Park Conservancy (APC) is looking for an additional $3 million in loan guarantees from the City of Winnipeg for its Diversity Gardens project.

The request comes after the conservancy acknowledged earlier this year the cost of the project has risen 30.4 per cent, from an estimate of $75 million to $97.8 million.

The extra $3 million would push the total guarantee from the city for the project to $20 million. APC is also asking to have the term of the guarantee extended three additional years to 2023, to allow for more private fundraising.

So far, the project — a gardens and plant conservatory project that is meant to reflect human and plant diversity — has secured $79.5 million from all levels of government, private donors and other sources.

APC president and CEO Margaret Redmond says the increase in the loan guarantee allows the conservancy to manage cash flow from private donors as work on the building continues.

"So this is a way of of the city helping us even out the the ebbs and flows of how that money flows to us, as you're undergoing construction where the cash is being spent very rapidly,"

Assiniboine Park Conservancy president Margaret Redmond says a request for a greater loan guarantee from the city will help manage cash flow for the Diversity Garden project. (CBC) Construction on the facility began in 2017, but several factors have pushed up the cost.

Steel prices have risen since construction was started and a delay in securing funding from the three levels of government pushed the cost up by $3 million.

Despite doing soil testing before construction, an underground stream was later found on the site and has pushed up the price of the foundations.

Redmond says the APC chose not to enter into a fixed-price contract for construction, instead using a project manager and a sequential tendering process — meaning it would pay for the project in stages.

That allows construction to get underway while different components of the project were tendered in stages, Redmond said.

Rising steel prices have affected the Diversity Garden project. (Justin Fraser CBC ) The advantage, Redmond told CBC News, was "the benefit of advancing the project more quickly, both to be eligible for government funding and to draw the interests of government."

Redmond says the building, with a roof made of an extremely lightweight and see-through plastic, is unlike any structure anywhere.

"There is nothing like it in the world. We're not building an office building, we're not building a school, and it is difficult to anticipate with a high degree of accuracy at the front end of a project like that."

Mayor Brian Bowman says he supports the project, but will review the request for the larger loan guarantee and expects his fellow councillors will have some questions as well.

"I think members of council will scrutinize it. It is an increased ask of the City of Winnipeg and councillors will do what's expected of them, which is review the report," Bowman said.

Councillor's on the city's executive policy committee will review and vote on the project next week.