Longtime opponents of the District’s plans to develop the 25-acre McMillan Sand Filtration Center site into retail, office and housing space have scored a victory — at least in principle. The D.C. auditor said last week that the bidding process to develop the high-profile property did not follow typical city protocol and the project should be put out to bid again.

The grassy city-owned site with large ivy-covered silos, at North Capitol Street and Michigan Avenue NW, was used as a water filtration plant until the 1980s and has been fenced off from the public for decades. (In 1909, it became the city’s first water cleansing system.) The city purchased the site in 1987 and officials say the plan has been to redevelop it, but constant disputes over what to do with the property have stalled plans.

In 2007, through a competitive bidding process, the city selected Vision McMillan Partners — formed by the construction companies EYA, Jair Lynch Development Partners and Trammell Crow Company — to devise a master plan for the site and explore development options. After that, the plan was to reopen the bidding process to determine who would score the rights to actually develop the property.

But, according to a letter from the D.C. auditor to D.C. Council Chairman Phil Mendelson (D) on Oct. 19, that second bidding process never occurred, and Vision McMillan Partners assumed the expanded role as developers for the site. Under an agreement with the city—which the letter notes the “Offices of Attorney General reviewed and approved for legal sufficiency”—Vision McMillan Partners also obtained the first right to buy parcels of the property after the entitlement process is complete.

“Although in its early stages that plan included a competitive process that resulted in the selection of Vision McMillan Partners, LLC (VMP) as the land development team, it ultimately resulted in a greatly expanded role and exclusive rights for VMP, all without the benefit of a competitive process,” the letter from auditor Kathleen Patterson states.

The letter continues: “Just as it is common knowledge in the construction industry that government practice is to re-bid a project if there is a material change to the scope of work, certainly, the change to VMP’s role and giving it exclusive rights are material changes that warrant a new competitive process.”

The D.C. auditor’s letter serves as a recommendation and is not binding, and it is unclear what changes, if any, the letter will yield. Mendelson and representatives from Vision McMillan Partners could not immediately be reached for comment.

Friends of McMillan Park, the vocal opposition group, which has long contended the bidding process was flawed, said Vision McMillan Partners and the city should not continue with their development plans. The group has argued the historic McMillan site should be preserved and transformed into park and community space.

“This is an opportunity to say to the council, ‘Maybe we need to reset this,'” said Jim Schulman, a member of Friends of McMillan. “Maybe this is the time to stop this right in its tracks and restart it on good footing.”

The D.C. Council Committee of the Whole is holding a hearing Monday morning to, in part, consider Mayor Muriel Bowser’s (D) request to extend by five years the time the city has to ready the land parcels so that it can be conveyed to developers, moving it from December 2016 to December 2021.