A recently completed project that filled in and smoothed out a large tract of light industrial property next to state Highway 14 could pay off handsomely for owners of the Vancouver site. But it could take a long time for potential buyers to come around, given Clark County’s sluggish industrial real estate market, said Bill Connelly, a Vancouver broker. He called the 35-acre site “shovel-ready,” a result of Vancouver-based Nutter Corp.’s work over the summer to fill the property.