Amid a yearlong delay, Denver’s voter-approved sidewalk construction and repair program took a key step forward Tuesday when a City Council committee gave preliminary approval to a plan to charge most property owners a flat rate of $150 a year starting in 2025. But some owners with large properties — including Denver’s Department of Parks and Recreation and other government entities with big tracts of land — could face significantly higher bills if they have more than 230 linear feet of sidewalk running along their lots. Impact fees of $3.50 per additional foot over 230 would be applied to those properties under the proposed changes.