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November 18, 2014
THE SAN DIEGO AND IMPERIAL COUNTIES CHAPTER OF THE
AMERICAN PUBLIC WORKS ASSOCIATION (APWA)
ANNOUNCE A SEMINAR DEMONSTRATING
The BMP Sizing Spreadsheeet – A Tool to Comply with Hydromodification
Management Requirements(2007 & 2013 MS4 Permits for San Diego Region)
The BMP Sizing Spreadsheet replaces the former on-line San Diego BMP Sizing Calculator
Seminar Logistic Jayne Janda‐Timba
Background & Introduction René Vidales
Example Project to CompareOnline Calculator & Spreadsheet Nobu Murakami
Question & Answer
Break
Example Problem with 2007 MS4 Permitand 2013 MS4 Permit Requirements Brendan Hastie
Question & Answer
Future of Sizing Factor Method 2013 MS4 PermitCompliance Laura Henry
Question & Answer
Closing
AGENDA
Seminar Logistics Housekeeping Please turn cell phones off Sponsors – Thank You! (County of SD, City of SD & APWA) Handouts−Speaker Profile−Bios−Acronyms−PowerPoint Presentation−Sizing Factors Matrix−Example Problem Handouts
3
Seminar Logistics Survey the audience……….−Design Engineer−Environmental Community−Development Community−Municipality−Regulators
PowerPoint available on Project Clean WaterWebsite: http://www.projectcleanwater.org
4
SPEAKERS PROFILE
René A. Vidales P.E, QSD, LEED GA, ENV SP
Program Director County of San Diego
Watershed Protection Program Department of Public Works
5510 Overland Avenue, Suite 410
San Diego, CA 92123 Phone: (858) 694-3246
Nobu Murakami P.E Assistant Project Engineer Rick Engineering Company Water Resources Division
5620 Friars Road
San Diego, CA 92110 Phone: (619) 291-0707 Fax: (619) 291-4165
Brendan Hastie, P.E., LEED AP Associate
Rick Engineering Company Water Resources Division
5620 Friars Road
San Diego, CA 92110 Phone: (619) 291-0707 Fax: (619) 291-4165
Laura Henry, M.S., P.E. Project Engineer
Rick Engineering Company Water Resources Division
5620 Friars Road
San Diego, CA 92110 Phone: (619) 291-0707 Fax: (619) 291-4165
[email protected] Jayne M. Janda-Timba, P.E., TOR,
QSD, QSP Associate
Rick Engineering Company Water Resources Division
5620 Friars Road
San Diego, CA 92110 Phone: (619) 688-1448 Fax: (619) 291-4165 Cell: (619) 540-6855
The BMP Sizing SpreadsheetA Tool to Comply with Hydromodification Management Requirements
Background & Introduction
René Vidales, PE, QSD, LEED GA, ENV SPProgram Coordinator, Watershed Protection Program
County of San Diego
November 18, 2014
Overview Background◦ MS4 Permits◦ Trainings
Introduction◦ History and Intent◦ What it is and Purpose◦ Components◦ Mechanics
2
Background
3
MS4 Permits 2007 MS4 Permit (R9-2007-0001)◦ Required PDPs to implement Interim Hydromodification
requirements◦ Interim requirements started January, 2008◦ Required Copermittees to develop Final
Hydromodification requirements◦ Final HMP released January, 2011
4
MS4 Permits 2013 MS4 Permit (R9-2013-0001)◦ Will be implemented December, 2015◦ Will continue to require PDPs to implement
Hydromodification requirements
5
Trainings Hydrologic Simulation Program Fortran (HSPF)◦ June 2009 Training
6
Trainings Online BMP Sizing Calculator◦ December 2010 Training
7
Trainings Online BMP Sizing Calculator◦ March 2011 Training
8
Trainings San Diego Hydrology Model (SDHM)◦ January 2012 Training
9
Trainings SCCWRP Hydromodification Screening Tool◦ June 2012 Training
10
Why this Training? Online BMP Sizing Calculator◦ Expired June 30, 2014
11
Why this Training? Online BMP Sizing Calculator◦ Expired June 30, 2014◦ Replaced by the BMP Sizing Spreadsheet
12
This Training BMP Sizing Spreadsheet◦ November 18, 2014 Training
13
Introduction
14
History Final Regional HMP includes a table of sizing factors
for various BMPs Online sizing calculator developed based on sizing
factors in HMP Online sizing calculator taken down and replaced
with spreadsheet. July 1, 2014
15
History Advantages of spreadsheet versus online sizing
calculator (tool)◦ Does not require internet hosting◦ Does not require major updates to maintain compatibility
with latest versions of internet browsers◦ Can easily be downloaded to an individual computer◦ Easy to use and understand
16
Intent One possible tool for use by applicants (SDHM,
SWMM, etc. can still also be used) Simple and easy to use Conservative results For use with common conditions (unusual designs
will require continuous simulation modeling) Sizes BMPs for treatment of the 85th percentile
event as well as hydromodification management
17
What it is and Purpose Spreadsheet to facilitate calculations from Final
HMP (Section 7) and Regional Model SUSMP (Chapter 4)◦ Some input parameters are controlled in order to align with the Final
HMP and the SUSMP◦ Some input parameters are determined based on project conditions◦ Spreadsheet output confirms adequacy of design◦ Particularly useful during preliminary design
18
Why use it? Online BMP Sizing Calculator is no longer online More reports with hand calculations for HMP
19
BMP Sizing Spreadsheet TabsLet’s look at the components within thespreadsheet…
20
Controlled selections◦ BMP Type◦ Low Flow Threshold◦ Soil Group◦ Slope Categorization◦ Rain Gauge
Components
21
Custom User Input◦ DMA name, size, surface type, and runoff factor◦ BMP area and volume◦ Depth of soil matrix◦ Orifice size
Components
22
Output◦ Minimum area and volume sizing criteria◦ Minimum and maximum allowable depth◦ Drawdown time
Components
23
Five (5) BMP Options in the Final HMP- Bioretention Facilities (Table 7-1)- Bioretention Plus Cistern Facilities (Table 7-2)- Bioretention Plus Vault Facilities (Table 7-3)- Flow-Through Planters (Table 7-4)- Infiltration Facilities (Table 7-5)
Select a BMP
24
Variable surface ponding depth Variable soil matrix depth 30-inch gravel storage layer Orifice 12-inch off bottom
Bioretention/Flow-Through Planter
25
Variable cistern depth and volume Overflow outlet to bioretention Controlled orifice outlet to bioretention
Bioretention Plus Cistern
26
Variable vault depth and volume Inflow from bioretention Emergency overflow outlet Controlled orifice outlet
Bioretention Plus Vault
27
Variable depth and volume No orifice discharge
Infiltration
28
Determined based on stream susceptibility−Per Section 6.2 of the Final HMP−High = 0.1Q2 (default value; no assessment is performed)−Medium = 0.3Q2
−Low = 0.5Q2
Low Flow Threshold
29
NRCS Hydrologic Soil Group−County Hydrology Manual , Appendix A−NRCS Web Soil Survey−http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx
Soil Group
30
Average Slope−Flat (< 5%)−Moderate (5% to 15%)−Steep (>15%)
Slope
31
Only three (3) options−Lindbergh−Oceanside−Lake Wohlford
Rain Gauge
32
Rain Gauge
Rain gauge information: http://bit.ly/1nHsWJe33
Rain Gauge and Soil Typehttp://bit.ly/1nHsWJe
34
Rain Gauge and Soil Typehttp://bit.ly/1nHsWJe
Click next to point
35
Rain Gauge and Soil Typehttp://bit.ly/1nHsWJe
36
Per Tables 7-1 to 7-5 of the Final HMP Expressed as a ratio of the contributing area
Minimum Surface Area
37
Per Tables 7-1 to 7-5 of HMP Expressed as a ratio of the contributing area−10-inch of surface ponding (for bioretention)−18-inch storage with 40% porosity (for bioretention)
Minimum Volume
38
Sized to discharge at the same rate as the low flow threshold
Calculated drawdown time must be less than 96 hours
Vector Control Plan required if more than 96 hours◦ County of San Diego Guidelines for Determining Significance ◦ County of San Diego Guidelines for Report Format and Content
Requirements http://www.sandiegocounty.gov/pds/procguid.html#vectors
Outlet Orifice
39
“Project Info” TAB
Mechanics
40
“BMP #1” TAB
Mechanics
41
“Orifice #1” TAB
Mechanics
42
“Orifice #1” TAB
Mechanics
43
“Orifice #1” TAB
Mechanics
44
“Rain Gauge Map” TAB
Mechanics
45
“Sizing Factors” TAB
Mechanics
46
To Compare Online Calculator with Spreadsheet
Example Problem
47
Comparison ofOnline San Diego BMP Sizing Calculator (Retired)
andBMP Sizing Spreadsheet (New)
Nobu MurakamiRick Engineering CompanyWater Resources Division
November 18, 20141
Use an example residential project to compare:1. Online San Diego BMP Sizing Calculator (Retired)
2. BMP Sizing Spreadsheet (New)
Overview
2
3
Example Residential Project
Total DMA = 1.22 AC
DMA to LID (w/o self-treating area) = 1.14 AC
Area Reserved for LID BMP
4
Additional Information / Assumptions:◦ The POC will be at the point where the runoff leaves the
project◦ No channel assessment performed – use low flow threshold
of 0.1Q2
◦ Design goal is to size a LID BMP using a “Cistern to Bioretention” tool
Example Residential Project
5
Basin Manager Tool:
• “Start” Tab – (Introduction/Overview for Basin Manger)
• “Project” Tab (Define Project Information)
• “Basin” Tab – (Define Basin Properties)
• “POC” Tab – (Low-flow Threshold Calculation)
• “Export” Tab – (Export/Import Project Information files)
LID Sizer Tool:
• “Start” Tab - (Introduction/Overview for LID Sizing)
• “DMA” Tab - (Define/Manage DMA Properties)
• “LID” Tab - (LID BMP Sizing Calculation)
• “Report” Tab - (Provides a summary of the project / LID Sizing)
• “Export” Tab - (Export/Import DMA/LID files)
Basin Manager Tool and LID Sizer Tool
Online San Diego BMP Sizing Calculator (Retired)
6
Online San Diego BMP Sizing Calculator (Retired)
“Project” TAB (Basin Manager Tool) – Online San Diego BMP Sizing Calculator
7“Basin” TAB (Basin Manager Tool) – Online San Diego BMP Sizing Calculator
Online San Diego BMP Sizing Calculator (Retired)
8“POC” TAB (Basin Manager Tool) – Online San Diego BMP Sizing Calculator
Online San Diego BMP Sizing Calculator (Retired)
9“DMA” TAB (LID Sizer Tool) – Online San Diego BMP Sizing Calculator
Online San Diego BMP Sizing Calculator (Retired)
10“DMA” TAB (LID Sizer Tool) – Online San Diego BMP Sizing Calculator
Online San Diego BMP Sizing Calculator (Retired)
Note: All of the DMAs have been defined, including the self-treating areas. However, the Online Calculator would not consider the self-treating DMA in sizing the LID BMP since the DMA did not contribute to the LID BMP.
11“LID” TAB (LID Sizer Tool) – Online San Diego BMP Sizing Calculator
Minimum Bioretention Area = 601.1 sf.
Minimum Cistern Volume (V1) = 6011.4 cf.
Flow Threshold – 0.1Q2 = 0.024 cfs
Orifice Size = 0.6 in.
Online San Diego BMP Sizing Calculator (Retired)
12
Available Tabs within the BMP Sizing Spreadsheet
• “Project Info” (Project Information)
• “BMP #1” (BMP Sizing Calculation)
• “Orifice #1” (Orifice Sizing Calculation)
• “Rain Gauge Map” (for reference)
• “Sizing Factors” (Lookup Tables from the 2011 Final HMP)
BMP Sizing Spreadsheet (New)
13“Project Info” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
14“Project Info” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
15“Project Info” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
16
• “Project”, “Basin” and “POC” tabs from the San Diego BMP Sizing Calculator have been consolidated into this “Project Info” Tab in the BMP Sizing Spreadsheet.
“Project Info” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
17“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
18“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
19“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
20“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
21“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
22“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
23“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
24
BMP Area = 8276.4 sf * (1.0) * (0.02) = 166 s.f.
Cistern Vol. = 8276.4 sf * (1.0) * (0.2) = 1655 c.f.
“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
25“Sizing Factors” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
26
Minimum Bioretention Area = 601.1 s.f. OK
Minimum Cistern Volume (V1) = 6011 c.f. OK
Note: All of the DMAs have been defined except the area for self-treating DMA has been purposefully left blank since this DMA does not drain to the LID BMP.
“BMP #1” TAB – BMP Sizing Spreadsheet
1.14 AC.
BMP Sizing Spreadsheet (New)
27“BMP #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
28“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
29“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
30“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
Existing Condition Cover:
• “Scrub” refers to a natural (pervious) cover
• “Urban” refers to a landscaping area with irrigation
• “N/A” applies only when “Impervious” is selected as the Soil Type
31“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
32“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
33“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
34“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
35
User’s Input
“Orifice #1” TAB – BMP Sizing Spreadsheet
BMP Sizing Spreadsheet (New)
36
Q & A
37
“Break”
Example Problem2007 MS4 Permit and 2013 MS4 Permit
Requirements
Brendan HastieRick Engineering CompanyWater Resources Division
November 18, 2014
Purpose
Compare the BMP Sizing Spreadsheet results for the example problem by inputting data based on 2007 MS4 and 2013 MS4 Permit Requirements
2
Presentation Overview
Goals of Example Problem Example Problem Information/Assumption Example Problem 2007 MS4 Permit Example Problem 2013 MS4 Permit Summary of the results based on the permit
changes that affect structural BMP design
3
• Identify and describe the required data (2007 MS4 vs. 2013 MS4)
• Describe the data entry procedures• Demonstrate how to operate the BMP Sizing
Spreadsheet by entering data for example problem
Goals of Example Problem
4
Redevelopment Project• We will examine one Basin draining to a storm drain
system. The POC will be at the point where the runoff leaves the project.
• Design goal is Treatment + Flow Control.• No channel assessment performed – use low flow threshold
of 0.1Q2 (High Susceptibility).• Rainfall Basin, Soil Type, Pre-Project Cover (2007 MS4
Permit), Pre-Project Slope, and DMA Surface Types are shown on the Example Problem-Redevelopment Project.
• Pre-Development Cover used for the 2013 MS4 Permit.
• Goals:
• Design a Flow Through Planter
Example Problem Information/Assumption
5
Example Problem Information/Assumption(Sheet 1 of 2)
6
Example Problem Information/Assumption(Sheet 2 of 2)
7
Available Tabs within the BMP Sizing Spreadsheet
• “Project Info”
• “BMP #1”
• “Orifice #1”
• “Rain Gauge”
• “Sizing Factors”
Example Problem Information/Assumption(BMP Sizing Spreadsheet)
8
• In the BMP Sizing Szpreadsheet, select the “Project Info” tab• Enter information in highlighted section• Note: “Rain Gauge” has dropdown menu to select either
“Lindbergh”, “Oceanside”, or “Lake Wohlford”. “Channel Susceptibility” has a dropdown menu to select either “High”, Medium” or “Low”.
Example Problem 2007 MS4 Permit
Project Info Tab9
• The Project info tab is completed.
• Next step is to select the “BMP #1” tab in the Spreadsheet
Example Problem 2007 MS4 Permit
Project Info Tab10
• The “BMP #1” Tab in the Spreadsheet has been selected• Note: The highlighted fields have been automatically
populated from the previously entered information in the “Project Info” tab
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Start Sizing BMP Footprint”
11
• Populate “BMP Name”, “BMP Native Soil Type”, and “BMP Type” fields• The selected soil type presents the soil type that the BMP will be located on. • The soil type will be used to determine the “BMP Infiltration Rate” of the BMP.• Note: Field “BMP Infiltration Rate” field has been automatically populated as the
user enters “BMP Native Soil Type” field. The example problem is to design Flow-Through Planter”; therefore, impervious liner has been selected that results in “N/A” BMP Infiltration Rate”.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
12
• “HMP Sizing Factors” and “Minimum BMP Size”fields will be automatically populated/calculated as the user enters information in the highlighted/blue fields for each DMA
• The goal is to obtain the BMP Sizes for “Surface Area”, “Surface Volume”, and “Subsurface Volume”
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
13
• Populate the selected blue fields for each DMA
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
14
• The first DMA has been entered. Continue the same exercise and enter information for the second DMA.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
15
• The second DMA has been entered. Continue the same exerciseand enter information for the third DMA.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
16
• The third DMA has been entered. Continue the same exercise and enter information for the fourth DMA.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
17
• The fourth DMA 4 has been entered. Continue the same exercise and enter information for the fifth DMA.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
18
• Now all five DMAs has been entered. The final results for theBMP Size are summarized within the box to the right.
-The minimum surface area is 810.216 s.f.-The minimum surface volume is 675 c.f.-The minimum subsurface volume is 468 c.f.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
19
• Enter the proposed BMP Size equal or close to the to the minimumBMP Size for startNote: To model for 2007 MS4 Permit, all DMAs with imperviousarea in the pre project condition shall be left empty in runoff factor field
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
20
• Enter the Soil Matrix DepthNote: This is only needed for bioretention or flow-through planterdesigns; 18 inches is the minimum depth)
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint”
21
• Enter the Selected Ponding DepthNote: Assumed 10 inches for start
Example Problem 2007 MS4 Permit
BMP #1 Tab
“Sizing BMP Footprint Complete”
22
• The “Orifice #1” Tab in the Spreadsheet has been selected• “Q2 Sizing Factor”, “Orifice Flow - %Q2”, and “Orifice Area”
will be automatically generated as the user enters data in thehighlighted fields
• Note: “DMA Name”, “Rain Gauge” and “DMA Area” columns havebeen automatically populated from the previously enteredinformation in the “BMP #1” Tab.
Example Problem – 2007 MS4 Permit
Orifice #1 Tab
“Start Sizing Orifice”
23
• “Soil Type”, “Cover”, and “Slope” information for the first DMA has been entered. Continue the same exercise and enter the Example Problem information for the second DMA
Example Problem 2007 MS4 Permit
Orifice #1 Tab24
“Sizing Orifice”
• “Soil Type”, “Cover”, and “Slope” information for the second DMA has been entered. Continue the same exercise and enter the Example Problem information for the third DMA
Example Problem 2007 MS4 Permit
Orifice #1 Tab25
“Sizing Orifice”
• “Soil Type”, “Cover”, and “Slope” information for the third DMA has been entered. Continue the same exercise and enterthe Example Problem information for the fourth DMA
Example Problem 2007 MS4 Permit
Orifice #1 Tab26
“Sizing Orifice”
• “Soil Type”, “Cover”, and “Slope” information for the fourthDMA has been entered. Continue the same exercise and enter the Example Problem information for the fifth DMA
Example Problem 2007 MS4 Permit
Orifice #1 Tab27
“Sizing Orifice”
• “Soil Type”, “Cover”, and “Slope” information for the ExistingCondition (Pre-Project Condition) for all DMAs has been entered
• Calculated “Max Orifice Diameter” is 0.54 inches. The size of0.54 inches shall be entered.
• Based on the entered 0.54 inches in the Orifice #1 tab, the“BMP Sizing Spreadsheet” will calculate the Drawdown Time.
• Ignore the drawdown time on this tab
Example Problem 2007 MS4 Permit
Orifice #1 Tab28
“Sizing OrificeCompleted”
• The size of 0.54 inches is entered in the Orifice #1 tab.• The calculated Drawdown Time is 20.1 hours.
Note 1: Check BMP #1 tab if the entered “Selected Ponding Depth” isbetween the required Minimum and Maximum depths.Note 2: If the minimum ponding depth is more than the maximumponding depth, adjust the BMP size, soil matrix depth and/or the selected pondingdepth.
Example Problem 2007 MS4 Permit
Orifice #1 Tab
“Computing Drawdown TIme”
29
• The initially assumed “Selected Ponding Depth” of 10 inchesis between the required minimum and maximum ponding depth;therefore sizing of the BMP footprint , Orifice Size, and Drawdown Time is completed.
Example Problem 2007 MS4 Permit
BMP #1 Tab
“BMP footprint size and
ponding depth check”
30
• In the BMP sizing spreadsheet, select the “Project Info” tab• Enter information in highlighted section• Note: “Rain Gauge” has dropdown menu to select either
“Lindbergh”, “Oceanside”, or “Lake Wohlford”. “Channel Susceptibility” has a dropdown menu to select either “High”, Medium” or “Low”.
Example Problem – 2013 MS4 Permit
Project Info Tab31
• The Project info tab is completed.
• Next step is to select the “BMP #1” tab in the Spreadsheet
Example Problem – 2013 MS4 Permit
Project Info Tab32
• The “BMP #1” Tab in the Spreadsheet has been selected• Note: The highlighted fields have been automatically
populated from the previously entered information in the “Project Info” tab
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Start Sizing BMP footprint”
33
• Populate “BMP Name”, “BMP Native Soil Type”, and “BMP Type”fields. The selected soil type presents the soil type that theBMP will be located on. Since the example problem is forFlow-Through Planter we selected Impervious Liner instead of soil type.
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
34
• “HMP Sizing Factors” and “Minimum BMP Size”fields will be automatically populated/calculated as the user entersinformation in the highlighted/blue fields in each DMA
• The goal is to obtain the BMP Sizes for “Surface Area”, “Surface Volume”, and “Subsurface Volume”
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BPM footprint”
35
• Populate the selected blue fields for each DMA
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
36
• The first DMA has been entered. Continue the same exercise and enter information for the second DMA
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
37
• The second DMA has been entered. Continue the same exercise and enter information for the third DMA
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
38
• The third DMA has been entered. Continue the same exercise and enter information for the fourth DMA
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
39
• The fourth DMA has been entered. Continue the sameexercise and enter information for the fifth DMA
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
40
• Now all of the DMAs has been entered. The final results for theBMP Size are summarized within the box to the right.
-The minimum surface area is 2291.256 s.f.-The minimum surface volume is 1910 c.f.-The minimum subsurface volume is 1375 c.f.
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
41
• Enter the proposed BMP Size equal to the minimum BMP sizefor start.
• Enter the soil matrix depth and the ponding depth fields
Example Problem – 2013 MS4 Permit
BMP #1 Tab
“Sizing BMP footprint”
42
• The “Orifice #1” Tab in the Spreadsheet has been selected• “Soil Type”, “Cover”, and “Slope” information for the Existing
Condition (Pre-Project Condition) for the first DMA has beenentered
• “Q2 Sizing Factor”, “Orifice Flow - %Q2”, and “Orifice Area” will be automatically generated as the user enters data in the highlighted fieldsNote: “DMA Name”, “Rain Gauge” and “DMA Area” columns have beenautomatically populated from the previously entered information in the “BMP #1” Tab
Example Problem – 2013 MS4 Permit
Orifice #1 Tab
“Start Sizing Orifice”
43
• “Soil Type”, “Cover”, and “Slope” information for all DMAs hasbeen entered.
• Calculated “Max Orifice Diameter” by the “BMP SizingSpreadsheet” is 0.21 inches. Based on the entered 0.21 inches, which is equal to the maximum orifice diameter, the “BMPSizing Spreadsheet” calculates the Drawdown Time.
• Since the drawdown time exceeds 96 hours, return to BMP tab and adjust the initial BMP size, and/or the soil matrix depth and/or the selected ponding depth.
Example Problem – 2013 MS4 Permit
Orifice #1 Tab
“Sizing OrificeCompleted”
44
• Proposed BMP Size and Soil Matrix Depth are iteratively increased untilthe Minimum Ponding Depth is less than the Maximum Ponding Depth.
◦ This indicates that a drawdown time less than 96 hours can be provided.◦ The selected ponding depth has been adjusted to 1.54 inches
Example Problem– 2013 MS4 Permit
BMP #1 Tab
“Increase the BMP Footprint and/orSoil Matrix Depth to Reduce DDT”
45
• After adjusting the BMP size, the soil matrix depth, and selected ponding depth, the drawdown time is now less than96 hours; therefore, sizing of the BMP is complete.
Example Problem – 2013 MS4 Permit
Orifice #1 Tab
“Check if BMP AdjustmentsResult in acceptable DDT”
46
Summary of the Results based on the permit changes that affect structural BMP design
47
Summary of the Results based on the permit changes that affect structural BMP design
The changes from the 2007 MS4 and 2013 MS4 have been implemented in the example problem to size the BMP Surface Area, Surface Volume, Subsurface Volume, and Orifice Size, and to calculate the Drawdown Time using BMP Sizing Spreadsheet
2007 MS4 compares proposed project site surface cover with the Pre-Project surface cover
2013 MS4 compares proposed project site surface cover with the Pre-Development project surface cover
Change in the results: 2013 MS4 requires bigger BMP Surface Area, Surface Volume, Subsurface Volume, Soil Matrix Depth, and smaller Orifice Size. Drawdown Time becomes a significant challenge for BMPs with small drainage areas!
48
Q & A
49
Future of Sizing Factor Method2013 MS4 Permit Compliance
Laura HenryRick Engineering CompanyWater Resources Division
November 18, 2014
Purpose How to apply sizing factors developed based on 2007
standards to meet 2013 standards
2
Presentation Overview Background and new terminology
2013 MS4 Permit changes that affect structural BMP design
Using sizing factors under the 2013 MS4 Permit
3
Background Standard for design of flow control BMPs for
hydromodification management requires continuous simulation modeling◦ Project-specific modeling (HSPF, SDHM, SWMM);
OR
◦ Sizing factor method (developed based on unit-area modeling)
4
Background Sizing factor method is static◦ Unit-area modeling prepared one time
◦ Not being revised for 2013 MS4 Permit
◦ BMP Design Manual will incorporate applicable sizing factors, leave out non-applicable sizing factors
5
New Terminology “BMP Design Manual” (formerly SUSMP)
“Pollutant control BMP” (formerly treatment control BMP)
“Retain” (infiltrate, evaporate, evapotranspire, harvest and use)
6
New Terminology “Structural BMP” encompasses:◦ Single purpose BMP (pollutant control OR
hydromodification management flow control)
◦ Dual purpose BMP (integrated BMP that combines pollutant control AND flow control)
7
New Terminology Bioretention (full retention/infiltration)
Bioinfiltration (partial retention/infiltration)
Biofiltration (no retention/infiltration)
Bioretention:No Underdrain
Bioinfiltration:Raised Underdrain
Biofiltration:Underdrain at Bottom
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New Terminology “Flow-Thru BMP”◦ Treatment control BMP that does not incorporate significant
biological methods
Vegetated swales, media filters, sand filters, dry extended detention basins
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Hydromodification management performance standards
Pollutant control performance standards
Permit Changes forStructural BMP Design
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Changes to applicability/exemptions
New requirement to protect critical coarse sediment yield areas
Requirement to control to “pre-development”condition instead of “pre-project” condition
Changes to Hydromodification Management Requirements
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“Pre-development” condition means runoff conditions from the project footprint based on:◦ Infiltration characteristics of the underlying soil
◦ Existing grade
◦ No impervious area
Changes to Hydromodification Management Requirements
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What “pre-development” condition requirement means for sizing factor method:◦ Unit runoff ratios for “urban” and “impervious” cover types
may not be used to determine pre-development Q2 for low flow orifice sizing under 2013 MS4 Permit
◦ Assume a natural pervious cover (“scrub”) for the pre-development condition
Changes for Sizing Factor Method
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2013 Permit Pollutant Control Hierarchy:◦ Retain onsite 85th percentile runoff (infiltrate, evaporate,
evapotranspire, harvest and use) Volume-based sizing – “Design Capture Volume” (DCV)
◦ Biofiltration if infeasible to retain runoff onsite
◦ Flow-thru treatment BMPs AND mitigate (off-site) for the DCV that was not retained onsite, if infeasible to retain or use biofiltration
Changes to Pollutant Control Requirements
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How/why do changes to pollutant control requirements relate to the sizing factors?◦ The change to DCV-based sizing and emphasis on retention
makes it impractical to apply some of the sizing factors that included a flow-based treatment component
◦ Names of sizing factor BMPs are not consistent with updated pollutant control terminology
Changes for Sizing Factor Method
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Sizing factor compatibility issues◦ “Bioretention” area sizing factor from “Cistern Plus
Bioretention” BMP
◦ “Bioretention” area sizing factor from “Bioretention Plus Vault” BMP
Changes for Sizing Factor Method
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Mapping of BMP names for integrated pollutant control and flow control BMPs
Changes for Sizing Factor Method
BMP Sizing SpreadsheetBMP Name
2013 Compatible BMPs
“Infiltration” Full retention category• “Infiltration basins”• “Permeable pavement (without underdrain)”• “Bioretention without underdrain”
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Mapping of BMP names for integrated pollutant control and flow control BMPs
Changes for Sizing Factor Method
BMP Sizing SpreadsheetBMP Name
2013 Compatible BMPs
“Bioretention” A or B soils:Full retention category• “Bioretention without underdrain”
C or D soils:with dead storage layer:
Partial retention category• “Bioinfiltration”
C or D soils:without dead storage layer:
No retention category• “Biofiltration”
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Mapping of BMP names for integrated pollutant control and flow control BMPs
Changes for Sizing Factor Method
BMP Sizing SpreadsheetBMP Name
2013 Compatible BMPs
“Flow-Through Planter”
No retention category• “Biofiltration”
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Mapping of BMP names for integrated pollutant control and flow control BMPs
◦ *“Cistern” is still useful for hydromodification management flow control volume sizing, but the treatment element of the BMP downstream of the cistern should be designed based on 2013 standards instead of sizing factors
Changes for Sizing Factor Method
BMP Sizing SpreadsheetBMP Name
2013 Compatible BMPs
“Bioretention plus Vault”
Not applicable
“Cistern plus Bioretention”
Not applicable*
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Evaluate feasibility to retain runoff for pollutant control, determine pollutant control category◦ Full, Partial, or No retention
Select a structural BMP Size the structural BMP for hydromodification
management For integrated BMPs, verify pollutant control
performance (check drawdown time for DCV)
How to
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Full retention◦ Sizing factors for “infiltration”
◦ Sizing factors for “bioretention” in A or B soils
Sizing Factors Applicable to Types of Pollutant Control Facilities
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Partial retention◦ Sizing factors for “bioretention” in C or D soils*
*retention storage must be provided below the underdrain, sizing factors will not provide credit for the retention storage
Sizing Factors Applicable to Types of Pollutant Control Facilities
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No retention◦ Sizing factors for “bioretention” in C or D soils, when there
is no retention storage provided below the underdrain
◦ Sizing factors for “flow-through planter”
◦ Sizing factors for “cistern”
Sizing Factors Applicable to Types of Pollutant Control Facilities
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Sizing Factors Applicable to Types of Pollutant Control Facilities
Full Retention BMP
PartialRetention
BMPNo Retention
BMP
2013 BMP Infiltration Basin
PermeablePavement Bioretention Bioinfiltration Biofiltration
Sizing Factor
“Infiltration”(A or B soils) X X
“Bioretention”(A or B soils) X
“Bioretention”(C or D soils)
X(with dead storage layer
below underdrain)
X(without dead storage
layer below underdrain)
“Flow-Through Planter”(C or D soils)
X
“Cistern” X
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Why is drawdown different for pollutant control sizing vs. hydromodification management?
Drawdown Time
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Sizing factor method is intended for simple projects◦ No diversion◦ No off-site area
Use project-specific continuous simulation model for more complex projects◦ Guidance and parameters will be provided in the BMP
Design Manual
Limitations on use of sizing factors
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Q & A
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