EVERETT — The Snohomish County Council reacted with collective sticker shock Monday after hearing the latest cost estimates for a new county courthouse.

Instead of the $75 million under discussion for a year, they’re now hearing estimates that exceed that figure by up to $80 million.

Deputy Executive Mark Ericks cautioned that it won’t be possible to pin down more precise numbers until the council decides on where to build the new courthouse.

“There wasn’t then, nor is there now, a $75 million option that will satisfy our needs,” Ericks told a council committee on Monday afternoon.

Ericks said he believed the low-ball estimate, developed during the watch of previous county executive Aaron Reardon, was “a matter of having unrealistic expectations or wishful expectations,” not of deliberate deception.

The deputy executive and county facilities staff on Monday presented variations on two possible courthouse sites.

One site is the plaza next to the existing 1967 courthouse. Building there could cost an estimated $109 million to $120 million, depending on whether the new structure is seven or nine stories.

Another possible site is the county-owned parking lot at the corner of Wall Street and Oakes Avenue across the street from Comcast Arena.

Building on the parking lot could cost $145 million for nine stories or $155 million for 10 stories. A drawback of that plan, aside from the hefty price, is having to buy out or use eminent domain for other property owners on the block. That location also would likely prevent the county from using an underground prisoner transport tunnel from the existing courthouse to the nearby jail.

There’s yet another choice that would involve moving the courts into temporary leased space, demolishing the old courthouse and building the new justice center in the same spot. That possibility was earlier discounted as too pricey, but is back on the table. The estimated price is about $130 million.

County staff have ruled out moving the historic Mission Building and putting the new courthouse in its place, Ericks said.

County Councilmembers want to spend the coming week reviewing the options and ways to pay for them. They’re planning to resume the discussion, possibly at the regular 10:30 a.m. meeting on Monday.

“A big part of what we do is how we pay for it,” Councilman Dave Gossett said.

The council in February decided that safety problems with the existing 1967 courthouse are too grave to be fixed through remodeling. Among the building’s woes are an inability to keep the public and court staff physically separated from defendants and convicted criminals; the presence of asbestos; multistory concrete facades at risk during an earthquake; and a lack of facilities for the physically disabled.

Solutions have been debated for years. A 2008 proposal estimated it would cost $163 million to build a new 10-story courthouse. That plan died for lack of political support.

Last year, the council tasked Reardon’s office and judicial leaders with exploring new ideas to fix the courthouse.

What emerged was a plan to build a seven-story structure with 20 courtrooms in the plaza on the courthouse’s north side. Staff would later move in, so the old building could be demolished. This spring, the county took out $75 million in bonds to start the project.

After Reardon resigned in May, the council asked new County Executive John Lovick and his staff to review the project.

Ericks, Lovick’s deputy, has been immersed in the review for months. On Monday, he detailed serious flaws with the original plan.

To start with, the $75 million option was based on a bare-bones structure without any noise-dampening carpet in the courtrooms. To reduce square-footage costs, plans for that building shrunk the width of hallways and other common areas.

That same option, with some extra space, minimal carpeting and other typical building features, is now the option pegged at $109 million.

That plan still fails to meet all projected space needs and comes with serious safety concerns, Ericks said.

The original option required building a new seven-story structure only about 10 feet from the existing courthouse. That puts staff in the old building at risk of getting hurt by construction equipment or falling materials, Ericks said. There’s also the likelihood of jackhammers and other loud construction equipment disrupting court next door.

Once finished, any building on the plaza would be vulnerable to truck bombs of the type used in the 1995 Oklahoma City Bombing, Ericks said.

“There was zero setback from the street,” said Ericks, who was responsible for protecting federal judges in his past job as U.S. marshal for the Western District of Washington.

The old plans came with space problems, too: The proposed building on the plaza would have been filled to capacity the day it opened. There would be no space for county prosecutors, who would get offices in most of the alternatives.

Planning for growth is important because the new courthouse likely would see daily use for the next 50 to 75 years.

Even with the new wrinkles, county leaders still hope to break ground on a new courthouse by the fall of 2014 and to finish the majority of the construction in 2016.

Noah Haglund: 425-339-3465, nhaglund@heraldnet.com.