SW Solutions Green Infrastructure 2-Day Training in Coos Bay

Stormwater Solutions Workshop –Coos Bay, OR - Feb 13, 2017

Stormwater Solutions Workshopin Coos Bay, OR on Feb 13 & 14, 2017

BROUGHT TO YOU IN PARTNERSHIP BY:


About MeMaria Cahill, Green Girl Land Development Solutions LLC


About Green Girl

Technical Writing/Editing, Graphics

Technical Assistance/Design Advice, Drafting

Workshops/Education & Outreach

Facilitation & Ecocharrettes

Construction Inspection (ODOT Certified)


Low Impact DevelopmentLand Use Applicability


Definitions: Low Impact Development

Low Impact Development is a pattern of land development that relies on a collection of techniques (aka Best Management Practices or BMPs, which are carefully selected) that preserve natural resources and collect and clean stormwater runoff to protect and improve water quality and availability.

Depending on BMPs, LID is great for resiliency (climate change, flooding, landslides, stream bank erosion, and saltwater intrusion).


Definitions: Best Management Practice

The EPA defines a best management practice (BMP) as "a device, practice, or method for removing, reducing, retarding, or preventing targeted stormwater runoff constituents, pollutants, and contaminants from reaching receiving waters.”

Is there really a best BMP?

How many doyou see here?

At least 4: Vactor truck, green street, trees, narrow street

Nope!


Site-scale Treatment Train

“Diverse and redundant systems are inherently more resilient.”1

1 Development Strategies for Promoting Coastal Resiliency & Sustainability

Minimize Impervious Area: Narrow street

Trees

Stormwater Planters in between trees?


Choose the Best mix of BMPs for your site

BMP Suitability Matrix


BMP Suitability MatrixColumn Headings Close-Up


Annual Water Balance Model: A Framework forWatershed Health, BEFORE Development

25% baseflow(infiltration)

50%

ev

apo-

tran

spira

tion

0.5% runoff

100%

ave

rage

An

nual

rain

fall

25%

gro

undw

ater

(infil

trati

on)

HERE INWESTERN OREGON

National average = 5%


Annual Water Balance AFTER DevelopmentExample: EVERYWHERE

0” baseflow(infiltration)

redu

ced

evap

o-tr

ansp

iratio

n

100%

rain

fall

year

ly a

vg98% runoff

2% e

vapo

-ra

tion

Redu

ced

infil

trati

on


“Before” & “After” Runoff Compared

0.5% runoff

98% runoff


Runoff Volumes: A Watershed Perspective

Natural WatershedUrbanized or Working Landscape Watershed

Slide from Stamberger Outreach Consulting

= HYDROMODIFICATION


LID BenefitsRunoff Volume from a Watershed Perspective

Erosion ->

Turbidity ->

Impacted Habitat ->

Very Real Recreational & Economic Impacts


Water Quality BEFORE Development

Some sediment


Water Quality AFTER Development

Sediment (air particulates)Nutrients

FecesOther debris

Runoff volume

Sediment/turbidityHydrocarbons

Heavy metals (particles & soluble)Other chemicalsRunoff volume

Sediment/turbidityfertilizerspesticidesherbicides

Runoff volume

16


Real Community Value

http://bit.ly/GC-GH “Social equity and community contribute to resilience.” 1


http://bit.ly/GC-GH


Stormwater HierarchyLevel 1

1. Lay out the site to minimize impacts to natural resources and to minimize impervious areas (Runoff Prevention).

Courtesy of NEED Development

“Simple, passive, and flexible systems are more resilient. 1



Minimize Impervious Area: Shared Parking Spaces BMP

Hierarchy Level 1: Lay out site to minimize impervious area and limit disturbance

Photo credit: Joseph Dewey


Minimize Impervious Area: Minimize Pavement Widths BMP

Oregon Department of Land Conservation and Development’s Model Development Code for Small Cities (Smart Growth principles included!): ttp://www.oregon.gov/LCD/TGM/pages/modelcode.aspx4


http://www.oregon.gov/LCD/TGM/pages/modelcode.aspx4


Minimize Impervious Area: Minimize Front Setbacks BMP



Minimize Impervious Area: Share a Driveway BMP



Minimize Impervious Area: Minimize Building Footprints BMP

Great example: Not ALL BMPs suitable for ALL stakeholders



Minimize Impervious Area: Minimize New Pavement BMP



Limit Disturbance: Construction Sequencing BMP

Starts in planning!

Protects soil resources by preventing compaction

Includes:Fencing! Fencing! Fencing!Haul roadsPhasing clearing & constructionCommon setbacksEquipment & grading choices



Conserve Fast(er) Draining Soils BMP= Infiltration Testing

For protected and developed areas. Infiltration testing needed for:•Cluster Development BMP•Porous Pavement (Runoff) BMP•Infiltration Rain Garden or LID Swale BMP•Infiltration Stormwater Planter BMP•Drywell BMP•Soakage Trench BMP•Vegetated Filter Strip (VFS) BMP•Downspout Disconnection BMP



Limit Disturbance: Conserve Fast(er) Draining Soils BMP

Infiltration rate in inches per hour

Guides site layout and where other BMPs are located



Limit Disturbance: Cluster Development BMP

Courtesy of AHBL

“Resilience transcends scales.”1



Consider connectivity

“Resilience transcends scales.”1



Limit Disturbance: Tree Protection BMP

Individual tree LOTS of ways to kill a tree in “Pitfalls and Common Mistakes”


Limit Disturbance: Minimal Foundations BMP

Great for flood prone areas and high groundwater tables

Photo courtesy of Taylor White, Flickr




In Massachusetts, one study found significant NFIP savings to a particular approach


Development Strategies for Promoting Coastal Resiliency and Sustainability




FEMA’s Homeowner’s Guide to Retrofitting

One sea level/climate adaptation method: Flow through basements



2. Prevent runoff by intercepting, evaporating, and/or infiltrating rainfall. (Runoff Prevention)

Step 2 Intercept runoff and evaporate and/or infiltrate


Water Quality and Land UseWhy Runoff from Lawns Cannot be Ignored

Courtesy of Pat Lando, Lando Landscape Architects


Water Quality and Land UseWhy Runoff from Lawns Cannot be Ignored

Created Table 8-1 of the Pennsylvania Stormwater Best Management Practices Manual & Table B5 of Center for Watershed Protection publication “Urban Stormwater Retrofit Practices”


Restored Soil BMP

REQUIRED on every new and re-development in Western WA. Great for retrofits, too (see left)

Hierarchy Level 2: Intercept runoff and evaporate and/or infiltrate


Restored SoilLawn Areas

from Soils for Salmon website



Restored Soil BMPPerennial Garden Areas



Revegetating Everywhere

Courtesy of Serena (Flickr)


Salt tolerant vegetation stabilizes fill added to address bank erosion.Photo: MA Office of Coastal Zone Management.


Depaving Existing Pavement BMP

DURING

AFTER



Contained Planters BMP and Vegetated Roofs BMP

Step 2 Intercept runoff and evaporate and/or infiltrate



Vegetated Roofs Monitoring

This roof is only 69% covered, yet peak flow reduction (i.e. flood storm management) is 96% annually!

City of Portland’s 2013 Monitoring Report


Porous Pavement BMP

Port of Portland installed 35 acres of porous asphalt



Porous Pavement BMPHierarchy Level 2: Intercept runoff and evaporate and/or infiltrate



3. Reduce runoff using BMPs with surface storage (i.e. ponding) that infiltrate and to a lesser extent, intercept and evaporate runoff and the rainfall they receive.

Remain

ing runoff

“Find and promote resilience in nature. 1



One Term for 3 BMPs: Vegetated Stormwater Facilities

Includes Rain Gardens, LID Swales, & Stormwater Planters PRIMARILY BECAUSE they all have pond storage (i.e. “ponding”)

“Locally available, renewable, or reclaimed resources are more resilient.” 1



Rain Garden BMPHierarchy Level 3: Reduce runoff with ponding facilities that infiltration AND evaporate


LID Swale BMPHierarchy Level 3: Reduce runoff with ponding facilities that infiltration AND evaporate


Stormwater Planter BMPHierarchy Level 3: Reduce runoff with ponding facilities that infiltration AND evaporate


Sizing Facilities for Climate ChangeHierarchy Levels 3 - 6

“Resilience anticipates interruptions and a dynamic future. 1


Excel Models Available on the Stormwater Solutions Website•SBUH shape, but calculates peak flows over 10 minutes periods using the rational method. •Then volumes are infiltrated based on design storm, infiltration rate, and facility size•NOT ALL BMPS REQUIRE HYDROLOGIC MODELING


Elements of LID for Ponding BMPsBMP-Scale Treatment Train: One Example

2 Pretreatment inlet basin captures

sediment and slows flows/reduces

erosion

Old Pretreatment inlet left in place, but could’ve been

removed after 2 was installed.

COMMON BUT NOT RECOMMENDED! HIGH

MAINTENANCE!

3 – 6 Rain garden treats and infiltrates runoff

1 Drainage area is swept regularly & is

maintained with coal-tar free asphalt

sealant


High Flow Bypass

1. Runoff flows into

inlet

2. Runoff fills stormwater

planter

3. Water backs up to this gutter elevation

4. Runoff bypasses to

next available facility

“Simple, passive, and flexible systems are more resilient.” 1



Safe Overland Route for the Very Large Storm

GREAT to see what a

safe overland

route!

HORRIBLE example of a

dispersion BMP!

• The term means a location where flows won’t go very often (i.e only during very large storms) and will protect infrastructure from damage.



4. Reduce runoff using BMPs with underground storage that infiltrate runoff.

Remain

ing runoff

Hierarchy Level 4: Infiltrate runoff underground


Porous Pavement (Runoff) BMPSizing Infiltration Facility

Roof area and sidewalks drain to rock trench below porous pavement

Porous Pavement

Extent of additional rock trench to manage runoff from roof and

sidewalks



Porous Pavement (Runoff) BMP

Siting and sizing of porous pavement (runoff)

•=

Siting and sizing of other infiltration facilities like rain

gardens

=



Porous Pavement (Runoff)Grants Pass Porous Pavement Demonstration

Take it away William Fletcher!


Drywell BMP

Different infiltration rates likely to occur throughout depth. This is an Underground Injection Control.

Photo courtesy of Howard’s Excavating, New Buffalo, MI



Soakage Trenches BMPHierarchy Level 4: Infiltrate runoff underground



5. Reduce runoff using flow-based BMPs without storage (i.e. conveyance) that infiltrate lower volumes and to a lesser extent, intercept and evaporate runoff and the rainfall.

runoff


WQ Conveyance Swale BMP

Flow based facility requires modeling by a qualified licensed engineer.

Hierarchy Level 5: Mostly treat water, but some might infiltrate and evaporate


WQ Conveyance Swale BMP

WQ Conveyance Swale is NOT:



Dispersion: Vegetated Filter Strip BMP

ODOT developing sizing method for infiltration. Currently only limited infiltration,mostly treatment.



Dispersion: Vegetated Filter Strip BMP

Photo courtesy of WADOT


ODOT has a new methodology for this.

Take it away William Fletcher!


Dispersion: Downspout Disconnection BMP

Lots of meaningless and unvetted ways have been tried in Portland:




6. Improve the water quality of runoff, without significantly reducing the volume, using a lined BMP or proprietary device.

runoff


Stormwater Planter BMPHierarchy Level 6: Only treat water (Infiltration and evaporation volume little to none.)


Lined Vegetated Stormwater BMPs

Photo courtesy of Lee Munson, City of Portland

Hierarchy Level 6: Only treat water (Infiltration and evaporation volume little to none.)


Creating an LID Project

Low Impact Development is an iterative process.

Collaboration during the entire process can reduce costs significantly!


Maria CahillPrincipal & Green Infrastructure Consultantc [email protected] Certified Women Business Enterprise (WBE) & a Registered Benefit Company in Oregon

Thank You for Your Attention!

Engineering

SW Solutions Green Infrastructure 2-Day Training in Coos Bay