Kempf was best known for his ambitious steel kinetic sculptures, which incorporated ready-made elements like ventilator turbines and windmills. His meticulously maintained sculpture garden, which adjoins his home and studio at the mouth of Cheyenne Canyon, showcases several mammoth pieces, some more than sixty feet tall. The sculpture garden has long attracted sightseers and occasionally created traffic jams, to the perpetual consternation of Kempf's wealthy neighbors in the luxurious residential enclave.
Kempf came to Colorado from Ohio in the early 1930s to study art at the then-nationally known Broadmoor Academy. He and his widow, Hedrick, have bequeathed the sculpture garden and house to the University of Colorado at Colorado Springs.