A quarter-percent sales tax for nine years and a large site along Interstate 70 are likely to be key parts of a police headquarters plan presented to voters in November.

City commissioners, meeting into early Wednesday morning, took no final action, but had their most signifiant discussion yet on a proposed $25 million police headquarters project.

The key points to emerge from the discussion:

• All five commissioners said they were interested in a proposal to create a new quarter-percent sales tax to fund the center. As plans now stand the quarter-percent sales tax would last for nine years, although that amount could go down if the cost of the building drops. Commissioners said they would insist the sales tax be written so that it automatically expires once the project is paid for. None of the commissioners were interested in using property taxes to pay for the project.

• Commissioner Bob Schumm wants architects to look for more ways to cut the cost of the building. Architects will deliver a report at the commission’s Aug. 5 meeting about what $20 million would build. The current construction estimate is $25.7 million, down from the $30 million projected before a recent round of design changes.

• A majority of commissioners expressed support for building the headquarters on a 47-acre site along McDonald Drive near the Kansas Turnpike interchange. The property is across the street from the Hallmark Cards production center.

A recently completed report by Lawrence-based Treanor Architects found the site has the highest acquisition costs and the highest site development costs of five sites studied by the city. The site, though, did have slightly shorter estimated drive times to key locations, such as the jail, the hospital and locations in West Lawrence, North Lawrence and south Lawrence. The report found the average drive time difference was only a couple of minutes, but Mayor Mike Amyx said the site particularly had much better access to North Lawrence than the other sites and was overall more versatile.

“It works well with the future expansion of the community to the west, but also has easy access to East Lawrence, North Lawrence, and West Lawrence today,” Amyx said.

Currently, site owner Hallmark Cards is asking about $3.2 million for the 47 acres and does not want to sell off a smaller parcel. The city needs only about 15 acres. Land costs are not part of the $25.7 million construction estimate.

Commissioners have said they could sell some of the excess land to help reduce the city’s costs. Already the Lawrence school district has expressed interest in part of the excess property for its maintenance shop needs. Commissioner Jeremy Farmer said he also believes the site could accommodate a new teen center for the Lawrence Boys & Girls Club, and Farmer said he would like to talk with a private developer who previously has been scouting the city for a location for a family fun center that would have go karts, batting cages, mini golf and similar activities.

Commissioners would have to pass the necessary ordinance to place the sales tax on the November ballot by Aug. 12. They may consider the ordinance at their Aug. 5 meeting.