STORMWATER DATA PROJECT & 2018 WHITEPAPER

Transcription

1 STORMWATER DATA PROJECT & 2018 WHITEPAPER MWD 2018 Conservation & Local Resources Committee May 8,

2 SOUTHERN CALIFORNIA WATER COALITION OVERVIEW Through measured advocacy, SCWC works to ensure the health and reliability of Southern California's water supply Member Organizations Across 8 Counties 2

3 SCWC STORMWATER TASK FORCE Develop regional consensus-based strategies & recommendations for utilizing stormwater effectively Identify potential issues Recognize opportunities and constraints related to stormwater management Provide a forum for discussion of challenges for watersheds within SoCal 3

4 SCWC PUMP UP THE VOLUME 4

5 STORMWATER CAPTURE DEFINED Stormwater Capture is the collection of rainfall runoff to supplement water supply 4 Distributed Infrastructure 1 Dams/Reservoirs 2 Spreading Grounds 3 Natural Bottom Channels 5

6 Stormwater Captured (MAFY) STORMWATER HISTORIC CAPTURE TREND Year Trend

7 2018 WHITEPAPER

8 BACKGROUND 2012 WHITEPAPER Initial understanding of stormwater cost per AF Consisted mainly of conceptual stormwater projects Findings presented to water and regulatory agencies 8

9 PURPOSE 2018 WHITEPAPER Improve understanding of actual stormwater capture volumes, costs, benefits, and performance across the region to inform future discussions Regional Collaboration Capture & Cost Analysis Constructed Projects Database Standardized Data Basis for Next Steps 9

10 APPROACH WHITEPAPER DEVELOPMENT 10

11 DATA COLLECTION AGENCIES CONTACTED Outreach to 30 agencies Received over 50 projects across the region Collaborated extensively Identified data collection challenges 11

12 DATA COLLECTION PROJECT TYPES Centralized for Recharge Distributed for Recharge Distributed for Direct Use Large projects that capture runoff for groundwater recharge Small projects that capture on-site runoff for groundwater recharge Small projects that capture on-site runoff for non-potable uses 12

13 DATA REVIEW ASSESSED DATA 32 Projects with Complete Data Actual Capture Data 54 Projects Received Actual Construction Costs 32 Full Year of Data 13

14 DATA SET 32 PROJECTS ANALYZED 29 Centralized 3 Distributed 25 Retrofit/Rehabilitation 4 New 3 New 14

15 DATA SET PRIMARY PROJECT BENEFITS Water Supply 27 projects Water Quality 3 projects Flood Risk Mitigation 2 projects 15

16 DATA SET SUMMARY OF PROJECTS Average Total Stormwater Construction Captured Cost 13,400 $132 million AFY Median AverageUnit Average Total Stormwater Rainfall Cost Stormwater Construction Captured Cost Retrofit $600/AF New Centralized 10.0 $6,900/AF13,400 AFY Distributed $25,000/AF $132 million New D.2 WY In $ From 32 Projects WY In 2017$ below Long-term Average of 15.2 WY In $ From 32 Projects Lo 16

17 LOCATION ACROSS SOUTHERN CALIFORNIA Centralized Centralized Projects (Avg Captured)!( No Data!(!( Less < 10 than 10 AFY AFY 100 1,000 AFY AFY 100-1,000 AFY!( Greater than 1,000 AFY!( > 1,000 AFY Decentralized Projects (Avg Captured) #* No Data #* #* Distributed Less than 10 AFY AFY Watershed < 10 AFY AFY Groundwater Basins Eastside Metropolitan Service Area Basin Inland Empire Basins Los Angeles County Coastal Plain Basin ± San Fernando Valley Basins 0 5 San Gabriel 10 Valley Basins 20 Miles Northwest Metropolitan Service Area Basin Orange County Basins San Diego County Basins 17

18 Annual Rainfall (inches) ANALYSIS ANNUAL CAPTURE & RAINFALL 40, Stormwater Captured (AFY) 1 30,000 20,000 10, Total annual stormwater captured by the 32 projects. 0 18

19 Stormwater Capture per Inch of Rainfall (AF/in) Cumulative Stormwater Projects in Operation ANALYSIS INCREASING CAPTURE ABILITY 2, , ,

20 ANALYSIS STORMWATER UNIT COST $1,000,000 Annual Cost per AF Captured ($/AFY) 1 $100,000 $10,000 $1,000 $100 $10 $1 $0 Centralized Projects Retrofit (25 Projects) 2 Centralized Projects New (4 Projects) Distributed Projects New (3 Projects) ,000 10,000 Average Actual Stormwater Captured (AFY) 1 Capital costs amortized over 30 years 2 Includes capture by the entire spreading grounds (does not isolate the marginal capture of the retrofit) 20

21 Average Stormwater Capture Cost ($/AFY) ANALYSIS RANGE OF CAPTURE COSTS $6,000 $5,000 $4,000 $3,000 $2,000 $1, th = $4,911 Median = $1,070 Median Unit Stormwater Cost Centralized Retrofit = $600/AF Centralized New = $6,900/AF Distributed = $25,000/AF $0 25 th = $ Stormwater Projects 21

22 SUMMARY KEY INSIGHTS & FINDINGS Retrofit Projects tend to be more cost effective than new projects Distributed Projects are usually designed for multiple benefits, a key one being water supply Good Monitoring is essential 22

23 DATA CHALLENGES COMMON PROBLEMS Actual Flow Data No monitoring Technical difficulties Difficult to isolate benefits from retrofit projects Actual Cost Data Difficult to isolate stormwater costs O&M costs are averaged over time Historical costs difficult to obtain 23

24 NEXT STEPS FUTURE OPPORTUNITIES SCWC Whitepaper on stormwater project implementation and funding challenges Study the relationship between stormwater capture and water supply yield Explore opportunities for multiple agencies to partner on stormwater projects Continue regional collaboration on stormwater data and monitoring 24

25 ACKNOWLEDGEMENTS THANK YOU Data Submission IEUA, OCFCD, EMWD, LACFCD, LADWP, LASAN, San Elijo JPA, Cities of Santa Monica and Torrance, County of Ventura Working Group HATCH Pavitra Rammohan IEUA Andy Campbell MWD Matthew Hacker and Miluska Propersi SCWC Rich Atwater 25

26 Questions? socalwater.org/stormwater Lee Alexanderson, P. E