The City of Kelso hired Gibbs & Olson, Inc. to delineate the stormwater basins within the city limits and to provide a Stormwater Management Plan (SWMP) for drainage within Phase 1 of the City of Kelso. This SWMP includes inventory of the existing structures and pipes, evaluation of the materials and function of the system, and recommendations for the improvement to the city’s Phase 1 system. A map of the city basin delineations is included in Appendix A.

The SWMP identifies deficiencies and recommends improvements for the following three elements of the storm drainage system:

• Pipe capacities
• Pipe materials
• Structure access and connections

Development of the SWMP included the following steps:

• Prepare an inventory of the existing Stormwater collection system
• Model the existing collection system in Phase 1
• Identify areas of insufficiency
• Prepare a Capital Improvement Plan (CIP) for recommended improvements