An arbitrator may have to decide whether the Oconomowoc Area (Wis.) School District will have to pay more than $680,000 in claims filed to the builder of a school under construction. Jansen Group Inc. is building Nature Hill Intermediate School, and after bad winter weather and delays of steel shipments, Jansen notified the district that the Aug. 1 deadline could not be met. Jansen filed a claim for about $990,000 proposing that their crews work overtime, at night and on weekends to make up time to meet the Aug. 1 deadline. The board and Jansen entered into a partial settlement of that claim under which the district agreed to pay $150,000 to the firm for accelerated work and a $150,000 bonus if the Aug. 20 deadline is met. But $683,935 of the Jansen claim remains unresolved.