We develop an O(kn3) time algorithm to establish the tradeoff graph of minimum total separation (i.e. width) versus spread (i.e. length) given k parallel river routing channels, each bounded by a single component at the top and bottom, and a total of n nets. This solves the two dimensional compaction problem for a special case of slicing structured layout: a single hierarchical level structure with single layer interconnections between adjacent components. It serves as a first cut toward solving the two dimensional layout compaction problem in a slicing structure with one layer interconnection.