West Desert Hot Springs Master Drainage Plan

West Desert Hot Springs, CA

PACE developed the Master Drainage Plan for a 47-square-mile portion of Palm Springs and Desert Hot Springs within Coachella Valley. The formalized drainage plan identifies regional solutions and ensures necessary implementation of the required flood control facilities associated with the many development areas in order to mitigate flood hazards. A comprehensive Geographic Information System (GIS) watershed mapping database was developed as a key planning tool and included all of the watershed characteristics and drainage facility planning constraints. The planning effort had to address many limiting physical and regulatory constraints in the plan formulation, which included environmental and flood hazards and fluvial characteristics of the alluvial fan.

The flood control / drainage facility Master Plan work program could be divided between the planning efforts for two general categories of drainage systems: regional flood control facilities and local subregional drainage facilities. The general steps of the planning process involved:

• Baseline engineering analysis of the existing conditions
• Constraint identification
• Alternatives plan formulation
• Engineering analysis of the alternatives and facility sizing
• Alternatives feasibility screening and selection analysis
• Refined engineering analysis of the recommended facility

The team developed a range of conceptual regional flood alternatives and applied a sophisticated alternative screening process to numerically rank and select regional flood control solutions. A drainage facility implementation program was developed through a prioritization analysis, and the resulting Master Plan document serves as a comprehensive watershed planning guidance document. The plan resulted in 50 miles of storm drain pipes, 10.6 miles of levee systems, nine stormwater flood control detention basins, and 37 major storm drain systems.

Key Features:

• Urban drainage master planning
• GIS watershed mapping
• Hydrology, hydraulic and sediment analyses
• Regional flood facility planning
• Hydrologic mitigation facilities planning
• Watershed stakeholder involvement
• Alternatives analysis
• Specialized process for selecting recommended plan
• Capital cost estimates