t-1 infiltration tools, v3.01
DESCRIPTION
T-1 Infiltration Tools, v3.01. Presented by Sean Penders (Caltrans) Eric Berntsen (SWRCB) Brian Currier (CSUS-OWP). Presented to Caltrans and RWQCB Staff May 10, 2013 Prepared by Caltrans and Office of Water Programs. Overview. Background - PowerPoint PPT PresentationTRANSCRIPT
T-1 Infiltration Tools, v3.01
Presented to Caltrans and RWQCB StaffMay 10, 2013
Prepared by Caltrans and Office of Water Programs 1
Presented by Sean Penders (Caltrans)Eric Berntsen (SWRCB)
Brian Currier (CSUS-OWP)
Overview
Background Prioritizing soil-based BMPs in the
Caltrans BMP Selection Process Conceptual infiltration model review Example: strip/swale and detention
basin treatment train Q&A
2
Background
Sustainable BMP goals from EPA, FHWA, SWRCB, RWQCB, & Caltrans
District Design needs Performance-based ranking for target
design constituents using statewide studies confirmed that infiltration was a key variable for load reduction
3
Consistency with Water Board Goals
Board resolution on sustainability Caltrans MS4 NPDES permit Based on the CGP Post Construction “Soil
Quality” credit in the CGP Water Balance Calculator
Phase I & II MS4
4
Background
http://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2008/rs2008_0030.pdf
Caltrans Conditions and Applicability
Not for flood Analysis• Analyzing small storm sizes• Only for water quality BMP sizing
Tailored to Caltrans• Compacted fill• Motorist safety• Useful statewide
5
Background
Caltrans Design Process: Project Planning and Design Guidance
(PPDG)
1-acre net new impervious post-construction BMP threshold Hwy
5000 sf non-hwy PPDG, T-1 Checklist: Treatment BMP
Selection• Performance-based ranking of BMPs• Requires infiltration calculation
6
Background
T-1 Checklist Process
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> 90 % strip/swales infiltration
no
no> 90%
treatment train infiltration
yes
Identify special-cases Add special BMPs
Add strips/swales
Add basinyes
Potential BMPs
Add Tier 1 BMPs
Estimate infiltrationRanking Algorithm
Select pollutant
Two-tiered
list
no
Need Infiltration
Prioritizing Soil-based BMPsPrioritizing soil-
based BMPs
MEP BMP Selection
T-1 Selection: Performance-Based Ranking Across Caltrans Studies
Performance-Based Ranking of Treatment BMPs. CTSW-RT-10-239.01. February 26, 2010 8
0%
20%
40%
60%
80%
100%
0% 20% 40% 60% 80% 100%
% L
oad
Redu
ction
% Infiltration
Dissolved Zn
EDB
EDBL
Delaware
Austin
Austin Earthen
MCTT
Wet Basin
Swales
Retrofit As/Ad > 0.2
Retrofit As/Ad < 0.1
RVTS As/Ad > 0.2
RVTS 0.1≤As/Ad≤0.2
RVTS As/Ad < 0.1
Prioritizing Soil-based BMPs
Performance-Based Ranking Across Caltrans Studies
9
Prioritizing Soil-based BMPs
Performance-Based Ranking of Treatment BMPs. CTSW-RT-10-239.01. February 26, 2010
Conceptual Infiltration Model Review
No surface storage• Strips• Swales• Natural and amended conditions• Infiltration Trenches
With surface storage• Detention Basins• Infiltration Basins
10
No Surface Storage:Strips and Swales Infiltration Tool
(SSIT)
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Native Soil
Amended Soil
Native Soil
Conceptual Model
With Surface Storage:Basin Infiltration Tool (BIT)
12
Conceptual Model
Example Project: New Highway
10 acres of new impervious surface Limited area for a strip/swale and
detention basin Type B soil ½ acre of pervious shoulder
13
Strip/swale and Detention
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Example
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Native Soil, Rate-Based Estimate
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Amendment Input
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Example
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Example
Adjust Soil Amendment
Use 9 inches instead of 4 to meet surface loading design requirements
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Example
SSIT Results Page
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Substantial benefits from amendment
Example
Adding a Downstream Basin
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Example
Basin Size Reduced Based on Maximum Upstream Losses
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Example
Basin Inputs Enter available area (100 ft x 50 ft) Verify soil infiltration rate
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Example
BIT Results
56% total treatment train infiltration! 42% upstream infiltration + 58% basin
treatment = 100% treatment!24
Example
Consistency with Water Board Standards and Goals
Consistent with State Water Board resolution on sustainability (Resolution No. 2008-0030)
Caltrans MS4 NPDES permit Based on the “Soil Quality” credit in the
CGP Water Balance Calculator
25
Links Basin Sizer
http://svctenvims.dot.ca.gov/wqpt/basinsizer.aspx
WQPT
http://svctenvims.dot.ca.gov/wqpt/wqpt.aspx
Infiltration Tool
http://www.dot.ca.gov/hq/oppd/stormwtr/t1.htm
PPDG
http://www.dot.ca.gov/hq/oppd/stormwtr/ppdg.htm
SWRCB
http://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2008/rs2008_0030.pdf
Caltrans NPDES MS4 permit
http://www.swrcb.ca.gov/water_issues/programs/stormwater/caltrans.shtml26
Questions and Comments
27