1. Post-Construction Requirements Design Challenges Dan Cloak, P.E.

2. Topics Low Impact Development Site Design –Design philosophy (what and why) –Benefits and some drawbacks Challenges to Achieving LID Site Design –Space constraints –Geotechnical and foundation design –Soil permeability –Groundwater

3. LID: What Preserve and replicate natural site hydrology Detain and retain runoff throughout the site

4. LID: Why? Why? Resilience. –Community engagement and acceptance –Education and awareness –Habitat –Temperature moderation –Air quality –Most robust and effective treatment –Hydrologic control

5. LID: Challenges More facilities to build, maintain, and inspect Higher costs More structural elements (sidewalls, overflows) More design effort –Integration with buildings, parking, and circulation

6. Design Challenges and Solutions Space constraints –Integrate LID at earliest stages of design Geotechnical and foundation design –Modify and enhance structures Low permeability of soils Groundwater

7. Space Constraints Solution: Incorporate site drainage and Stormwater Control Measures in preliminary site plan

8. Require Stormwater Plan Early Pre-Application Meeting Completed Application “Deemed Complete” Section Review CEQA Review Conditions of Approval Planning Commission Detailed Design Plan Set and Permit Application Construction

9. 4% Sizing Factor (Tier 2) ½ Acre 4% 30 ft

10. Strategies to Minimize Facility Size Minimize impervious area Make landscaped areas self-treating or self-retaining Disperse runoff to landscape

11. Example Commercial Site

12. Example Residential Subdivision

13. Non-LID Treatment

14. Steep Site, Remediated Slide

15. Next to Building Foundations

16. Bioretention & High Groundwater 6" 18"

17. Summary: LID Design Challenges Design for resilience Disperse runoff where possible Use the sizing calculator to iterate design Get the geotech working with you