The Capitol Subsurface Infiltration GallerySCVURPPP Green Stormwater Infrastructure Planning

November 29, 2018

Robin Lee, PE

Agenda:

Project OverviewInitial Pump DesignRevised DesignLessons Learned Construction PicsQuestions

2 of 20

The Project:

10.32 acresResidentialRetail/CommercialStorage

3 of 20

Site Plan

4 of 20

Initial Design:

90’x 56’ vault12’ tallPump to bioretentionBio sized on pump rate2,300 sf treatment

5 of 20

Bird’s Eye

6 of 20

Cross Section

7 of 20

Revised Design:

Perc. Rate – 30in/hr10-ft below gradeOpen bottom vaultC3 = infiltration42’ x 90’ 6’ tall25% smaller footprint

8 of 20

Percolation does NOT equal Infiltration!

Percolation Rate = 30 in/hr

Infiltration rate = 9 in/hr

Factor of Safety = 2.5

Infiltration

Percolation

9 of 20

BAHM Reduction Factor

10 of 20

Site Plan

11 of 20

Bird’s Eye

12 of 20

Profile

13 of 20

Cross Section

125.9’3.9’ ponds and infiltrates

Water Quality Volume0.45 ac-feet required 0.57 ac-feet provided

14 of 20

Vault System

15 of 20

Weir Plate Design

16 of 20

Excavation

17 of 20

Light Compaction

18 of 20

Gravel Layer & Vaults

19 of 20

Questions

20 of 20

Project Partners