Three more trade contractors have filed mechanics' liens against two different general contractor groups that worked on delivering projects that are part of the $850-million Barack Obama Presidential Center in Chicago. O'Neil Construction, filed a mechanics lien seeking more than $40 million for concrete work on the project. Liens filed in Cook County typically take three to four weeks to show up in the county system after being filed. Contractors filing liens for their work on the Home Court include structural steel subcontractor Area Erectors, which is seeking nearly $620,000. Lakeside Alliance said in a statement: "The Obama Presidential Center involved multiple structures, thousands of design documents and hundreds of trade partners and community businesses.