📋 Case Study
Urban Mixed-Use Redevelopment in Austin, TX
Meeting City of Austin Watershed Protection Department (WPD) LID requirements while avoiding downstream flooding
🏗️ Project Overview
12-acre infill development with 60% impervious cover and adjacent floodplain constraints
🎯 Challenge
Meeting City of Austin Watershed Protection Department (WPD) LID requirements while avoiding downstream flooding
🔧 Design Approach
Integrated bioretention cells + permeable pavers + underground detention vault with real-time level monitoring
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
LID Volume Reduction
Runoff × (1 − C_LID)
Result: 78%
Met 75% WPD volume capture mandate
Bioretention Sizing
Required Volume = Q_p × t_storage
Result: 1.4 ac-ft
Based on 10-year, 24-hr storm
Detention Vault Overflow Rate
Q_out = C × L × H^1.5
Result: 28 cfs
Below 100-year channel capacity
📊 Results
Zero post-development peak flow increase; full WPD approval in first submission; $220k construction premium offset by 12-year utility rebate💡 Lessons Learned
- •Pre-submission coordination with WPD prevents redesign loops
- •Real-time sensors validated 92% model accuracy
- •Permeable paver maintenance plan reduced long-term O&M costs by 37%
✅ Key Takeaways
- 1Pre-submission coordination with WPD prevents redesign loops
- 2Real-time sensors validated 92% model accuracy
- 3Permeable paver maintenance plan reduced long-term O&M costs by 37%