Keller Associates recently completed a comprehensive update to the Grants Pass Stormwater Master Plan. The plan updated the existing XPSWMM model based on extensive field investigations, surveying, integration of interconnected irrigation ditches, data from multiple flow monitoring periods, and model calibration. Plan deliverables included identified deficiencies, recommended improvements, and a capital improvement plan. Keller Associates also worked closely with the City and irrigation district in developing a Memorandum of Understanding (MOU) for the mutual use of facilities, and developed the framework for a new stormwater utility.

This project earned the ACEC Oregon Engineering Excellence Award’s Honor Award.

Services Provided:

• Updating and calibrating stormwater model, including incorporation of 25 miles of major canals
• Computer modeling of approximately 100 miles of open channel and piped conveyance systems
• Flow monitoring at 16 concurrent locations
• Assisting City of Grants Pass and the Grants Pass Irrigation District in creating a MOU and subsequent Inter-Governmental Agreement
• Developing annual O&M and pipeline replacement program
• NPDES MS4 Phase II permitting support
• Supporting ongoing development of stormwater utility rate