1. CH2M HILL & Air Sciences September 2005 Sand Mass Trends at Great Basin CSCs, ‘00-’05 Owens Lake Dust Mitigation Project Sand Mass Trends at Great Basin CSCs, ‘00-’05 Owens Lake Dust Mitigation Project Los Angeles Department of Water & Power CH2M HILL and Air Sciences Los Angeles Department of Water & Power CH2M HILL and Air Sciences Bishop, September 28-29 2005

2. CH2M HILL & Air Sciences September 2005 Goal of Analysis To examine spatial and temporal trends in the District sand mass collections, in light of construction activities on the lake bed

3. CH2M HILL & Air Sciences September 2005 Data Data provided by District, –Jan 2000-July 2005 Data summarized by year & month CSC locations categorized by location and/or control status

4. CH2M HILL & Air Sciences September 2005 Factors Considered Meteorology Dust Control Measures (DCMs) Construction activities

5. CH2M HILL & Air Sciences September 2005 Meteorology Windspeed Precipitation Temperature & Relative humidity

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10. CH2M HILL & Air Sciences September 2005 Meteorology: Results Wind speed in ’00-’05 similar to long term trend Wind speed similar during all construction phases Precipitation variable by year Temperature and relative humidity similar to long term trend

11. CH2M HILL & Air Sciences September 2005 Base Map

12. CH2M HILL & Air Sciences September 2005 Construction Periods Pre-construction1/00-10/00 NSS construction11/00-12/01 Managed Vegetation1/02-8/02 Phase 2 shallow flood9/02-4/03 Interim (no activity)5/03-8/03 Phase 3 construction9/03-9/04 Phase 4 shallow flood10/04-7/05

13. CH2M HILL & Air Sciences September 2005 Analysis of Sand Mass Trends Two levels of Analysis: 1.Trends by CSC category 2.Trends by individual CSCs

14. CH2M HILL & Air Sciences September 2005 Sand Mass Trends by Category High throughout entire period –Shallow Flood Phase 4 and 5 –Keeler Dunes High initially, decrease with DCMs –NSS Zone 2 –Managed Vegetation –Shallow flood Phase 2

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17. CH2M HILL & Air Sciences September 2005 Sand Mass Trends by Category High initially, construction increase –NSS Zone 1 Low initially, construction increase –2002-2004 SCA

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20. CH2M HILL & Air Sciences September 2005 Results by CSC Group Analysis indicates increased sand mass over time due to construction activities However, trends in sand mass are unique on a CSC by CSC basis

21. CH2M HILL & Air Sciences September 2005 Construction Evidence by CSC Distance to construction activity Timing of construction activity Wind speed and precipitation

22. CH2M HILL & Air Sciences September 2005 Result s Map

23. CH2M HILL & Air Sciences September 2005

24. CH2M HILL & Air Sciences September 2005 Results: By individual CSCs Evidence Category# Cells% Unlikely, low sand mass 1612 Unlikely, high sand mass 3928 Inconclusive 2921 Possible evidence 10 7 Strong evidence 4432 Total 138

25. CH2M HILL & Air Sciences September 2005 Results: ’02-’04 SCA Cells only Evidence Category# Cells% Inconclusive 515 Possible evidence 720 Strong evidence 2165 Total 33

26. CH2M HILL & Air Sciences September 2005 Sand mass affected by: Meteorology:No DCM:Yes Construction:Yes

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28. CH2M HILL & Air Sciences September 2005 CSC Categories No controls in grid cell NSS: Shallow flood Zones 1 and 2 Keeler Dunes SSS: Managed Vegetation Shallow flood: Phases 2,4,5 SCA based on ’02-’04 GB analysis

29. CH2M HILL & Air Sciences September 2005 Example 1: CSC 7240- <500 ft to Zone 1 berm

30. CH2M HILL & Air Sciences September 2005 Example 2: CSC 7454- ~ 400 ft to Mainline Rd.

31. CH2M HILL & Air Sciences September 2005 Example 3: CSC 7541- ~ 400 ft to Phase 4 berm