INSTRUCTORS
MEGHAN FELLER, PE
Project Engineer
Key project experience:
Stormwater planning, design,
and NPDES Permit compliance
REBECCA DUGOPOLSKI, PE
Senior Engineer
Key project experience: Stormwater
monitoring, design, hydrologic
modeling and NPDES Permit
compliance
introduction
hydrologic modeling basics
performance standards
BMP modeling specifics
wrap up
AGENDA
LEARNING OBJECTIVES
1. Gain a basic level of knowledge using WWHM
and MGSFlood to predict pre‐ and post‐
development flow volumes and durations.
2. Learn basic, entry level skills to size bioretention,
permeable pavement, rainwater collection
systems, and vegetated roofs in residential and
commercial settings using WWHM and
MGSFlood.
3. Understand the advantages and limitations of
WWHM and MGSFlood and gain an awareness of
additional modeling tools for specific predictions
LOGISTICS
SCHEDULE
6‐hour training (5 hours classroom
instruction, 1 hour for lunch)
Lunch is provided
OTHER LOGISTICS
• Restrooms
• Food
• Turn off cell phones
• Sign in and sign out
PROGRAM OVERVIEW
• 2012: Public and private
partners engage state
legislature to fund program
• June 2012: LID Training
Steering Committee convened
• 2012‐2013: Washington State
LID Training Plan developed:
www.wastormwatercenter.org/
lid‐background/
• 2014: Training program built
from state LID Training Plan
PROGRAM OVERVIEW
• 49 trainings in western and
eastern WA in 2014‐2015.
• 42 trainings in western and
eastern WA in 2015‐2016.
• 39 trainings offered in
western and eastern WA in
2017.
• Three levels: Introductory,
Intermediate, and Advanced.
• Statewide LID Certificate now
available.
PROJECT LEAD
ADDITIONAL TRAINING SUPPORT
OVERVIEW OF PROGRAM
CORE TEAM
Introduction to LID
for Inspection &
Maintenance Staff
INTRODUCTORY
INTERMEDIATE
ADVANCED
Intermediate LID
Design: Rainwater
Collection Systems &
Vegetated Roofs
Intermediate LID
Topics: NPDES Phase
I & II Requirements
Intermediate
LID Design:
Permeable Pavement
Intermediate
LID Design:
Hydrologic Modeling
Advanced Topics in
LID Design:
Bioretention
Advanced Topics in
LID Design:
Permeable Pavement
Advanced Topics in
LID Design:
Hydrologic Modeling
Advanced Topics in
LID Design: Site
Assessment,
Planning & Layout
Advanced Topics in
LID Design: Rainwater
Collection Systems &
Vegetated Roofs
Advanced Topics in LID
Design: Bioretention
Media and Compost
Amended Soils
OVERVIEW OF PROGRAM
Advanced Topics for
Long‐term LID
Operations:
Bioretention
Intermediate
LID Design:
Bioretention
Advanced Topics for
Long‐term LID
Operations:
Permeable Pavement
Intermediate LID
Design: Site
Assessment, Planning
& Layout
Introduction to LID
for Inspection &
Maintenance Staff
INTRODUCTORY
INTERMEDIATE
ADVANCED
Intermediate LID
Design: Rainwater
Collection Systems &
Vegetated Roofs
Intermediate LID
Topics: NPDES Phase
I & II Requirements
Intermediate
LID Design:
Permeable Pavement
Intermediate
LID Design:
Hydrologic Modeling
Advanced Topics in
LID Design:
Bioretention
Advanced Topics in
LID Design:
Permeable Pavement
Advanced Topics in
LID Design:
Hydrologic Modeling
Advanced Topics in
LID Design: Site
Assessment,
Planning & Layout
Advanced Topics in
LID Design: Rainwater
Collection Systems &
Vegetated Roofs
Advanced Topics in LID
Design: Bioretention
Media and Compost
Amended Soils
OVERVIEW OF PROGRAM
Advanced Topics for
Long‐term LID
Operations:
Bioretention
Intermediate
LID Design:
Bioretention
Advanced Topics for
Long‐term LID
Operations:
Permeable Pavement
Intermediate LID
Design: Site
Assessment, Planning
& Layout
INTERMEDIATE LID DESIGN
HYDROLOGIC MODELING
Training Program
Statewide LID
introduction
LID PRINCIPLES: Pre‐developed forest
INTRODUCTION
2012 LID Technical Guidance Manual for Puget Sound
LID PRINCIPLES: Developed condition
INTRODUCTION
2012 LID Technical Guidance Manual for Puget Sound
LID PRINCIPLES: Stormwater Impacts
INTRODUCTION
HOW DO WE GET THERE?
Quantify the effects of development
Size and evaluate the performance of stormwater management practices
TRADITIONALLY…
• Primarily detention and large scale infiltration
• Detention pond/vault/pipe or infiltration pond/gallery
REGIONAL MANAGEMENT
INTRODUCTION
• Detention hydrograph (single event)
• Match peak flows, increased duration:
OK for piped system with direct discharge to a lake or ocean?
OK for discharge to a creek?
OK for discharge to a wetland?
Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Managed Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Managed Runoff (cfs)
Time (hrs)
Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Managed Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Managed Runoff (cfs)
Time (hrs)
Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Managed Runoff (cfs)
Time (hrs)
REGIONAL MANAGEMENT
INTRODUCTION
May limit erosive flows in stream but we have
not mimicked hydrologic cycle (no evaporation,
no groundwater recharge, different hydrograph)
Detentionâ‰
INTRODUCTION
REGIONAL MANAGEMENT
Detention (continuous simulation)
Match peaks and durations
Durations percent of time a particular flow occurs
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.000001
0.00001
0.0001
0.001
0.01
0.1
1.0
Exceedance Probability
Flow (cfs)
Predeveloped
Postdeveloped
INTRODUCTION
FLOW DURATIONS
INFILTRATION VS DETENTION
Infiltrating Facilities
Detention Facilities
If not detention, then what?
INTRODUCTION
FLOW DURATIONS
LOW IMPACT DEVELOPMENT (LID):
Stormwater Management Strategy
INTRODUCTION
• Site design & planning techniques
emphasizing conservation
• Use of small‐scale & distributed
engineered controls to closely mimic
pre‐development hydrologic processes
• Minimizing the concentration of
stormwater
• Careful assessment of site soils and
strategic site planning to best use those
soils for stormwater management
LID Principles: Site Design And Planning
INTRODUCTION
• Minimize disturbance
• Reduce impervious
surface
• Protect and restore
native soils and
vegetation
• Manage stormwater
close to the source in a
system of distributed
practices
• Disconnect impervious
surfaces
Traditional
LID
LID BMPs: Small‐Scale Engineering Controls
INTRODUCTION
• Infiltration
• Filtration
• Storage
• Evaporation
• Transpiration
Synonyms for LID BMPs:
Green Stormwater Infrastructure (GSI), Integrated Management Practices (IMPs), and On-Site Stormwater Management BMPs
Conserve or regain
pre‐developed hydrologic
functions
hydrologic modeling basics
LID PRINCIPLES: Stormwater Impacts
HOW DO WE GET THERE?
Quantify the effects of development
Size and evaluate the performance of stormwater management practices
HYDROLOGIC MODELING
HYDROLOGIC MODELING BASICS
PURPOSE OF HYDROLOGIC MODELING
HYDROLOGIC MODELING BASICS
• A: Use of mathematical
equations to estimate hydrologic
cycle components and facility
performance based on:
• Weather patterns
• Land use
• Soil
• Topography
Source: http://www.und.nodak.edu/
• Q: What is hydrologic
modeling?
PURPOSE OF HYDROLOGIC MODELING
HYDROLOGIC MODELING BASICS
• Q: Why do we use hydrologic
models?
• A: Characterize hydrologic
conditions:
• Predeveloped
• Current
• Post‐project
• Design mitigation
2012 LID Technical Guidance Manual for Puget Sound
PURPOSE OF HYDROLOGIC MODELING
HYDROLOGIC MODELING BASICS
• Q: When does hydrologic
modeling enter into your
project?
• A: Start to finish
• Preliminary design (sizing)
• Final design (optimization)
• Demonstrate requirements
met (permit submittals)
MODELING TOOLS
HYDROLOGIC MODELING BASICS
• Single‐event models
• Appropriate for conveyance sizing
• Continuous models
• Required for sizing BMPs to meet the LID
performance standard (MR#5), treatment
(MR#6), or flow control (MR #7)
• Simplified sizing tools
• Allow sizing without hydrologic modeling
MODELING TOOLS: Single‐Event Models
HYDROLOGIC MODELING BASICS
• Input single storm event, typically synthetic
• Output peak flow rates
• Typical methods and models
• SCS
• SBUH
• Rational Method
• StormShed
• HydroCAD
• SWMM
• HEC‐HMS
• SUSTAIN
Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Time (hrs)
Runoff (cfs)
Rainfall (in)
Pre‐developed Runoff (cfs)
Post‐developed Runoff (cfs)
Time (hrs)
MODELING TOOLS: Continuous Models
HYDROLOGIC MODELING BASICS
• Input long‐term rain and evaporation
• Output continuous runoff, peak flow, & duration
• Accounts for antecedent conditions
• Is the soil already saturated?
• Is your bioretention facility already full of water?
• Common models:
• HSPF
• WWHM
• MGS Flood
• KCRTS
• SWMM
Time (hrs)
Runoff (cfs)
Rainfall (inches)
Rainfall (in)
Unmanaged Runoff (cfs)
Managed Runoff (cfs)
Rainfall (in)
Unmanaged Runoff (cfs)
Managed Runoff (cfs)
Time (hrs)
Runoff (cfs)
Rainfall (inches)
Rainfall (in)
Unmanaged Runoff (cfs)
Managed Runoff (cfs)
SUSTAIN
InfoWorks
MODELING TOOLS: WWHM/MGSFlood Input
• Meteorological Data
• Rainfall (5‐min, 15‐min, hourly)
• Evaporation (daily)
• Land Cover Types
• Regional calibrated parameters (Dinicola 1990)
• Impervious areas
• Timing: slope, length of flow path, surface roughness
• Volume: depression storage
• Pervious areas
• Timing: slope, length of flow path, surface roughness
• Volume: depression storage, vegetative cover, soil type
• BMP Configurations
HYDROLOGIC MODELING BASICS
Meteorological Data
Select precipitation region
Select mean annual
precipitation depth
MGS Flood
MODELING TOOLS: WWHM/MGSFlood Input
HYDROLOGIC MODELING BASICS
Meteorological Data
Select precipitation region
Select mean annual
precipitation depth
MODELING TOOLS: WWHM/MGSFlood Input
HYDROLOGIC MODELING BASICS
Meteorological Data
Select precipitation region
Select mean annual
precipitation depth
MODELING TOOLS: WWHM/MGSFlood Input
HYDROLOGIC MODELING BASICS
MGS Flood
Land Cover
SWMM
By comparison…
MODELING TOOLS: WWHM/MGSFlood Input
HYDROLOGIC MODELING BASICS
MODELING TOOLS: Simplified Sizing Tools
HYDROLOGIC MODELING BASICS
• Kitsap County: Pavement sized as function of
contributing impervious area and precipitation
BMP
Design Infilt.
Rate (in/hr)
Flow Control Standard
(MR #7)
Sizing Equation
Permeable Pavement Facility
6 inch
ponding depth
0.25
0.1100
‐ 1.0536
Area (sf) = Impervious Area
(sf) x [M x Precip. (in) + B] 0.5
0.0187
+ 0.4945
1.0
0.0048
+ 0.3531
Permeable Pavement Surface
Slope <= 2%
0.13 – 0.249
0.005
Aggregate Depth (in) =
M x Precip. (in)
≥ 0.25
0.01
MODELING TOOLS: Simplified Sizing Tools
HYDROLOGIC MODELING BASICS
GSI‐Calc
Kitsap County Pre‐Sized Calculator
performance standards
NPDES MUNICIPAL STORMWATER PERMIT:
Minimum Requirements (MRs)
PERFORMANCE STANDARDS
Preparation of Stormwater Site Plans
Construction Stormwater Pollution
Prevention Plan (SWPPP)
Source Control of Pollution
Preservation of Natural Drainage
Systems and Outfalls
On‐Site Stormwater Management
Run‐off Treatment
Flow Control
Wetlands Protection
Operations and Maintenance
Implementation options:
• List #1
• List #2
• LID Performance Standard
MINIMUM REQUIREMENT #5
SEA Street
PERFORMANCE STANDARDS
MR #5 applies to:
MINIMUM REQUIREMENT #5
Projects
triggering MR
#1‐#5 only
List #1 or
LID Performance
Standard Applies
Projects
triggering MR
#1‐#9
List #2 or
LID Performance
Standard Applies
PERFORMANCE STANDARDS
Project Type & Location
Requirement
Development (new or
redevelopment) on any parcel
inside the UGA, or development
outside the UGA on a parcel less
than 5 acres
LID Performance Standard
and BMP T5.13
List #2
(applicant option)
Development (new or
redevelopment) outside the UGA
on a parcel of 5 acres or larger
LID Performance Standard
and BMP T5.13
MINIMUM REQUIREMENT #5: Projects
Triggering MR #1‐#9
PERFORMANCE STANDARDS
MINIMUM REQUIREMENT #5: List Option
Consider all the BMPs in the order listed and use the first BMP that
is considered feasible.
Roofs
Other Hard Surfaces
Lawn and Landscaped
Areas
PERFORMANCE STANDARDS
MINIMUM REQUIREMENT #5: List #1
Roofs
Other Hard Surfaces
Full Dispersion or Downspout Full
Infiltration (T5.30 or T5.10A)
Rain Gardens or Bioretention
(T5.14A or B)
• > 5% of drainage area
Downspout Dispersion Systems
(T5.10B)
Perforated Stub‐out Connections
(T5.10C)
Full Dispersion (T5.30)
Permeable Pavement, Rain
Gardens, or Bioretention
• (T5.15, T5.14A, T5.14B)
• Rain Garden or Bioretention
area > 5% of drainage area
Sheet Flow Dispersion, or
Concentrated Flow Dispersion
(T5.12 or T5.11)
Lawn and Landscaped
Areas
Soil Quality and
Depth (BMP T5.13)
PERFORMANCE STANDARDS
MINIMUM REQUIREMENT #5: LIST #2
Roofs
Other Hard Surfaces
Full Dispersion or Downspout Full
Infiltration (T5.30 or T5.10A)
Bioretention (T5.14B)
• > 5% of drainage area
Downspout Dispersion Systems
(T5.10B)
Perforated Stub‐out Connections
(T5.10C)
Full Dispersion (T5.30)
Permeable Pavement (T5.15)
Bioretention( T5.14B)
• > 5% of drainage area
Sheet Flow Dispersion, or
Concentrated Flow Dispersion
(T5.12 or T5.11)
Lawn and Landscaped
Areas
Soil Quality and
Depth (BMP T5.13)
PERFORMANCE STANDARDS
Source: Ecology SWMMWW Presentation
Match pre‐developed durations from 8% of the 2‐year
peak flow to 50% of the 2‐year peak flow
MINIMUM REQUIREMENT #5:
LID PERFORMANCE STANDARD
Flow Control
LID
LID Performance
Standard
addresses lower,
more frequent
stormwater
flows
Flow Control
Standard
addresses higher,
less frequent
stormwater flows
PERFORMANCE STANDARDS
MINIMUM REQUIREMENT #6 and #7:
PERFORMANCE STANDARDS
• Runoff treatment (MR #6)
• Infiltrate 91 percent of the total runoff volume through soil
meeting Ecology treatment criteria (for infiltration BMPs)
• Flow Control (MR# 7)
• Match pre‐developed discharge rates from 50% of the 2‐year
peak flow up to the full 50‐year peak flow
• Other flow control standards
• Combined sewer or capacity constrained basins (peak‐based
standards): apply only in specific cities with flow control
exempt areas with limited conveyance capacity
• Wetland protection
FLOW DURATION STANDARDS
PERFORMANCE STANDARDS
• LID performance standard (MR #5)
• Flow control (MR #7)
LID
Flow Control
Precipitation: 38 inches annually (Seattle)
Predeveloped condition: Forest on till
Design Infiltration Rate: 0.25 inch/hour
Flow
Duration
Standard
Treatment
Standard
LID Standard
5,000 sf
5.1%
345 sf
6.2%
1090 sf
PERFORMANCE STANDARDS
SIZING COMPARISON EXAMPLE: Bioretention
Configuration: Vertical walls
Ponding depth: 6 inches
27.8%
240 sf
LID COST ANALYSIS: Small Commercial
Scenario 7 to 10
Lot
1 Acre
Total Impervious 35,500 sf
Roof Area 5,000 sf
PERFORMANCE STANDARDS
LID COST ANALYSIS: Results Scenario 8
Scenario 8 – Small Commercial – 2005 – Till
Soil Quality and Depth
Detention Tank
Stormwater Treatment Planter Vault
HMA Parking
PERFORMANCE STANDARDS
LID COST ANALYSIS: Results Scenario 10
Scenario 10 – Small Commercial – 2012 – Till
Soil Quality and Depth
Bioretention
HMA Parking
Detention Tank
PERFORMANCE STANDARDS
LID COST ANALYSIS: 2005 manual
PERFORMANCE STANDARDS
LID COST ANALYSIS: 2012 manual (with…