Risk Level Determination (RLD) for the Construction General Permit (CGP)
description
Transcript of Risk Level Determination (RLD) for the Construction General Permit (CGP)
December 2010
Risk Level Determination (RLD) for theConstruction General Permit (CGP)
December 7, 2010
December 2010Webinar 1: Risk Level Determination
Agenda
2
December 2010Webinar 1: Risk Level Determination
Meet the Presenters
Facilitator: Jeff Bold
Presenter: Tim Sobelman
Q&A Panel: Tim Sobelman
Robert Schott
Mike Marti
3
December 2010Webinar 1: Risk Level Determination
Agenda
4
December 2010Webinar 1: Risk Level Determination
Communication During Webinar
Your phone is automatically muted.
Please submit your questions electronically on the Q/A portion of your screen.
Questions will be addressed after the presentation is completed.
5
December 2010Webinar 1: Risk Level Determination
Agenda
6
December 2010Webinar 1: Risk Level Determination
Caltrans CGP Guidance
Division of Environmental Analysis – Webinars, Water Quality Dispatch, etc.http://www.dot.ca.gov/hq/env/stormwater/cgp/index.htm
Division of Construction – CPD/CPB, SWPPP Preparation Manual, etc.http://www.dot.ca.gov/hq/construc/stormwater/stormwater1.htm
Division of Design – Risk Level Determination Guidance, CGP Cost Estimating,
Specifications, etc.– Risk Level Determination (RLD) Webinar– RUSLE2 Training (RL Determination module)
7
December 2010Webinar 1: Risk Level Determination
Risk Level Determination
Today’s presentation will:
1) Discuss what Risk Levels mean to a Caltrans Construction Sites2) Describe the site-specific data that is needed to conduct a RL
Determination 3) Discuss the programs/websites that are available to obtain the site
data4) Go over two Methods of conducting a RL Determination 5) Answer questions related to calculating a project Risk Level
8
December 2010Webinar 1: Risk Level Determination
Caltrans Project RLD Guidance
http://www.dot.ca.gov/hq/oppd/stormwtr/index.htm
Goals:- Determine appropriate Risk
Level for each site:- Accurate Slope Length and
Steepness values - Construction during dry seasons
could reduce sediment risk- GIS Map / Individual Method
9
December 2010Webinar 1: Risk Level Determination
Risk Level Determination Factors
Completed for pre-construction conditions Only two factors determine Risk Level:
– Sediment– Receiving Water
3 possible Risk Levels
10
December 2010Webinar 1: Risk Level Determination
Combined Risk Level
For each project sediment and receiving water risks are combined
Combined Risk Levels: 1 2 3 low medium high
11
December 2010Webinar 1: Risk Level Determination
What does Risk Level 1 mean?
Level 1 SWPPP Requirements for a QSD/QSP Visual monitoring Annual reports
Combined Risk Levels: 1 2 3 low medium high
12
December 2010Webinar 1: Risk Level Determination
What does Risk Level 2 mean?
Combined Risk Levels: 1 2 3 low medium high
Level 2 = Level 1 requirements plus: Rain Event Action Plan (REAP) Numeric Action Level (NAL)
– pH 6.5-8.5, – turbidity < 250 NTU
Storm water sampling during rain events
13
December 2010Webinar 1: Risk Level Determination
What does Risk Level 3 mean?
Combined Risk Levels: 1 2 3 low medium high
Level 3 = Level 1 + Level 2 requirements plus: Numeric Effluent Limits (NEL)
- pH 6.0 – 9.0 - turbidity < 500 NTU
Receiving water sampling during rain eventsConduct bioassessment testing on sites > 30 acres
14
December 2010Webinar 1: Risk Level Determination
RLD – Where to start…
http://www.swrcb.ca.gov/water_issues/programs/stormwater/constpermits.shtml
Appendix 1 - Risk Determination Worksheet (select ‘Excel’)
15
December 2010Webinar 1: Risk Level Determination
Open SWRCB Excel fileGIS Map Method
Use GIS Map Method to determine: Step 1) Sediment RiskStep 2) Receiving Water RiskStep 3) Combined Risk Level
16
GIS Method is used at each phase (PID, PAED, PS&E). Document in the Storm Water Data Report.
December 2010Webinar 1: Risk Level Determination
Sediment Risk Factors
Based on Revised Universal Soil Loss Equation (RUSLE) Soil loss (tons/acre/year) = R • K • L • S • C • P
R = rainfall erosivity (EPA website)K = soil erodibilityL = length of slope S = slopeC = coverP = practices
C and P are assumed to be constant; no data needed for risk calculation
17
December 2010Webinar 1: Risk Level Determination
Step 1 - Sediment Risk
1) Locate site2) Obtain KLS3) Calculate R4) Sediment Risk = R • KLS
18
December 2010Webinar 1: Risk Level Determination
Truckee Bypass
Project located adjacent to the Truckee River
39°20’23.44” N; 120°10’16.20” W 19
December 2010Webinar 1: Risk Level Determination
Rainfall Erosivity (R)
Enter site name, project duration
20
http://cfpub.epa.gov/npdes/stormwater/LEW/lewCalculator.cfm
December 2010Webinar 1: Risk Level Determination
Rainfall Erosivity (R)
Enter site location (latitude/longitude)
21
December 2010Webinar 1: Risk Level Determination
Rainfall Erosivity (R)
For a 13 month job:
R = 10.34
22
December 2010Webinar 1: Risk Level Determination
Sediment Risk - KLS GIS Map
1) Locate site2) Obtain KLS
23
December 2010Webinar 1: Risk Level Determination
Sediment Risk - KLS GIS Map
KLS = 1.6
Truckee Bypass Project
24
December 2010Webinar 1: Risk Level Determination
Calculate Sediment Risk
Sediment Risk = R • KLS
= 10.34 • 1.6
= 16.54
Low: <15 tons/acreMedium: ≥15 to <75 tons/acreHigh: ≥75 tons/acre
Medium Sediment Risk
25
December 2010Webinar 1: Risk Level Determination
Sediment Risk
Change from a 13 month project to a 12 month project
R declines from 10.34 to 9.03
= 9.03 • 1.6
= 14.45
Low: <15 tons/acreMedium: ≥15 to <75 tons/acreHigh: ≥75 tons/acre
LOW Sediment Risk
26
December 2010Webinar 1: Risk Level Determination
Step 2 - Receiving Water (RW) Risk
Locate watershed and identify receiving water body
TMDL and/or 303(d) listed for sediment?OR
Designated Beneficial Uses? • Spawn and• Cold and• Migratory
If No to both – Low RW riskIf Yes to either – High RW risk
27
December 2010Webinar 1: Risk Level Determination
Water Quality Planning Tool
http://www.owp.csus.edu/research/stormwater/tools/wqpt.htm
Locates site, watershed by Post-Miles
28
December 2010Webinar 1: Risk Level Determination
Water Quality Planning Tool
TMDL & 303(d)listed waterbodies
Receiving Water located in Truckee River Watershed
Truckee River TMDL listed forsediment
29
December 2010Webinar 1: Risk Level Determination
Water Quality Planning Tool – Truckee River
Spawn
Migratory
Cold
30
December 2010Webinar 1: Risk Level Determination
Receiving Water Risk Estimate – Truckee River
TMDL sediment – Yes Cold+Spawn+Migratory – YesReceiving Water = High Risk
31
December 2010Webinar 1: Risk Level Determination
Combined Risk Level
Sediment Risk = Low
Receiving Water Risk = High
Combined Risk = Level 2
32
December 2010Webinar 1: Risk Level Determination
Sediment Risk – Individual Method
Use when detailed analysis may produce more favorable RLD
Consider Individual Method at PS&E (unless detailed project information is available earlier).
Document in the Storm Water Data Report.
33
December 2010Webinar 1: Risk Level Determination
Individual vs GIS Map Methods
34
December 2010Webinar 1: Risk Level Determination
Sediment Risk – Individual Method
35
December 2010Webinar 1: Risk Level Determination
Individual Method - Sediment Risk Factor Worksheet
R Factor
K Factor
LS Factor
Sediment Risk
36
December 2010Webinar 1: Risk Level Determination
How do we get the data?
R, K factors require latitude/longitude
Sources for latitude/longitude:1) Web Browser Post Mile Query Tool (Caltrans website)
2) Google Earth
3) Caltrans District 8 GIS website: http://sv08arcgis/cgp2009/
37
December 2010Webinar 1: Risk Level Determination
Soil Erodibility (K)
http://soils.USDA.gov
38
December 2010Webinar 1: Risk Level Determination
Soil Erodibility (K)
Find specific K factor for area of influence (AOI)
K = 0.24
39
December 2010Webinar 1: Risk Level Determination
Slope Length and Steepness (LS)
Example: weighted average for project area are:L = 50 feet, S = 50%
40
LS= 5.16
December 2010Webinar 1: Risk Level Determination
Sediment Risk – Individual Method
Sediment Risk was reduced from:
15.54 tons/acre (Med) (GIS MAP Method)
to
12.81 tons/acre (Low)(Individual Method)
41
December 2010Webinar 1: Risk Level Determination
Receiving Water Risk
Same as GIS Method
RW Risk = High
42
December 2010Webinar 1: Risk Level Determination
RLD Truckee Bypass
43
Sediment Risk = Low(Individual Method)
Receiving Water Risk = High
Combined Risk Level 2
December 2010Webinar 1: Risk Level Determination
Alternative Rainfall Erosivity (R)
For a 5 year, 4 month job:
R = 49.74
44
December 2010Webinar 1: Risk Level Determination
Calculate Sediment Risk – GIS Map Method
Sediment Risk = R • KLS
= 49.74 x 1.6
= 79.58 (High Sediment Risk)
Low: <15 tons/acreMedium: ≥15 to <75 tons/acreHigh: ≥75 tons/acre
Risk Level 3
45
December 2010Webinar 1: Risk Level Determination
Calculate Sediment Risk – Individual Method
Sediment Risk = R • KLS
= 49.74 x 1.24
= 61.68 (Medium Sediment Risk)
Low: <15 tons/acreMedium: ≥15 to <75 tons/acreHigh: ≥75 tons/acre
Risk Level 2
46
Medium
December 2010Webinar 1: Risk Level Determination
Caltrans D8 GIS
District 8 has compiled a unique GIS http://sv08arcgis/cgp2009/ This GIS integrates many data sources to provide the user:
– Street and aerial photography location information– Sediment Risk – Latitude/Longitude (R), GIS map method (KLS),
individual method (K, R, topographic info)– Receiving Water Risk – draft SWRCB GIS
How to use D8 GIS described in Caltrans RLD Guidance
47
December 2010Webinar 1: Risk Level Determination
Caltrans District 8 GIS
On Caltrans website: http://sv08arcgis/cgp2009/
latitude and longitude
48
December 2010Webinar 1: Risk Level Determination
Caltrans District 8 GIS - Imagery
49
December 2010Webinar 1: Risk Level Determination
K Factor - Caltrans District 8 GIS
K= 0.24
50
December 2010Webinar 1: Risk Level Determination
Caltrans District 8 GIS – Planning Watershed Boundaries
51
December 2010Webinar 1: Risk Level Determination
Summary
Which RLD method?– Start with GIS Map Method PID and PAED
• Simple, fast, conservative – Individual Method (optional) PS&E
• More detailed• Use when GIS method results in borderline
sediment risk
52
December 2010Webinar 1: Risk Level Determination
Where to go for more information?
This site contains: RLD Guidance RUSLE2 8-hour training course A recording of this presentation A copy of the Q&A Session
53
http://www.dot.ca.gov/hq/oppd/stormwtr/index.htm
December 2010Webinar 1: Risk Level Determination
Agenda
54