A legal delay in school construction would cost the South Washington County district millions in additional building and finance costs, court documents allege.

The filings come in response to a lawsuit by three Cottage Grove residents, who say that a recount of votes cast in November in Independent School District 833 wrongly granted passage of a $96 million bond issue.

Susan Richardson, Andrea Mayer-Bruestle and Leilani Holmstadt challenged a canvassing board’s Nov. 20 decision to declare five ballots as “non-votes,” which resulted in passage of Ballot Question 2.

That question, one of three presented to voters, called for approving general obligation bonds to build a new middle school in Cottage Grove, and renovate the current Oltman Middle School in St. Paul Park to house the Nuevas Fronteras Elementary School.

Michelle Kenney, the school district’s attorney, recently petitioned in Washington County District Court to require the plaintiffs to provide a $9.3 million surety bond to cover cost increases. The suit will cause delays, resulting in substantial cost overruns, and a bond is necessary “for the protection of the School District and its taxpayers,” she wrote in her court filing.

Her petition includes an affidavit from architect Paul Youngquist, who forecast increased building costs of nearly $3 million. A second affidavit, from financial adviser Joel Sutter, said rising interest rates from delayed bond sales would cost the district an additional $6.4 million.

Kenney has asked Judge Gregory Galler to dismiss the suit — in part, she said, because the clerk of the school district, Katie Schwartz, wasn’t named as the “contestee” as state law requires. Kenney’s motion will be heard Friday in Stillwater.

In their initial filing, Richardson, Mayer-Bruestle and Holmstadt alleged that the canvassing board didn’t follow Minnesota law in determining voter intent when evaluating the contested ballots. Their attorney, Erick Kaardal of Minneapolis, said the board never concluded that it was “impossible” to determine the intent of the voter.

Had the Canvassing Board “not erred in its determinations” and instead found that the contested ballots were “no” votes instead of “non-votes,” Kaardal said, Ballot Question 2 would have failed due to a tie: 6,840 voting “yes” and 6,840 voting “no.”

Voters approved the first ballot question, which will add about $10.3 million (or $525 per student) to the general fund each year for the next 10 years. They rejected the third question, which requested funding to expand each of the district’s three high schools and make improvements at each of the district’s elementary schools.

Mayer-Bruestle led an effort this fall to defeat all three ballot measures, arguing that the school district wasn’t fully revealing costs in its annual budget. She also ran unsuccessfully for school board.