LID and Green Infrastructure - Benefits and Practices · Transportation/Roadway Projects – Opportunity to incorporate retrofits, ie bioswales, pervious parking, green infrastructure

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FSA Fall Seminar

LID and Green Infrastructure -

Benefits and Practices

Jack Merriam, Senior Environmental Scientist

Applied Sciences Consulting

Brett Cunningham, PE, Director of Water Resources

Jones Edmunds


Outline

Introduction

LID Effectiveness

Regulatory Issues

Local and Programmatic Issues


Low Impact Development (LID) a.k.a. :

Low Impact Development/Design- – approach to land development(redevelopment) that works with nature to

manage stormwater as near its source as possible.

Light Imprint- – a la Andres Duany/Thomas Low Incorporates a transect for appropriate

techniques…T1Natural, T2Rural, T3 Suburban, T4 General Urban, T5 Urban Center, T6 Urban Core

Green Infrastructure- – weaves natural processes into built environment using vegetation and

soils to manage rainwater where it falls

All of these are

multidisciplinary

approaches


Conventional Stormwater Management

Engineered end of pipe

Focuses on controlling peak flow rate and suspended solids

Fails to address cumulative hydrologic alterations that cause increases in stormwater volume and runoff rates & cause excessive erosion and degradation of stream channels.

Often doesn’t treat well for nutrients

LID can complement conventional techniques by reducing volumes and peak flow rates allowing for smaller conventional infrastruture, pipes, ponds, etc.


Hurdles to LID Implementation

Need to reconcile with other regulations

Need to have buy-in and credits, especially with WMDs, in order to become widely used

Inertia…..resistance to change – Regulators…”permit what we know”

– Practitioners….”design what we know”

– Developers ….”do what we’ve always done”

– Maintainers….”that’s more costly, takes longer, much more complicated”

Maintenance…. Many think it’s way more difficult and expensive than it needs to be!

Need better cost-benefit analysis- benefits for reducing temperatures, shade, creating walkable communities, recharge, cost avoidance by preventing pollution downstream in the bay, stream, etc.

Liability: don’t let the lawyers design our stormwater and roadway projects!


Help with Regulations

http://water.epa.gov/infrastructure/greeninfrastructure/upload/gi_webinar_part5.pdf

http://water.epa.gov/infrastructure/greeninfrastructure/upload/gi_webinar_part5.pdf


Top Five Code Issues

Dealing with Fire Department- often

oppose narrow streets, etc.

Eliminating “Why Bother “ Provisions

Dealing with Curb Requirements-often a

requirement

Landscaping Requirements can be severe

limitation

Standards or Guidance? One size doesn’t

fit all!


Examples of

Eliminating “Why Bother” Provisions

Must assume D (low infiltration) soil for sizing LID

facilities – even with a soils report that says it’s A

(excellent infiltration) soil!

Must assume all parking surfaces will be impervious for

purposes of calculating runoff volume – even if

permeable surfaces are used.

Landscaped buffer strips must be surrounded by a curb

no less than five (5) inches in height – with no waiver for

breaks/curb cuts or use as stormwater management

measures.

One tree must be planted within thirty (30) feet of every

surface parking space – constrains creative use of

landscaping


Questions


LID Effectiveness


Study Concept

Vs.


Planning

“All else is equal”

• Age of development

• Soils

• Imperviousness

7-month period

• Wet and dry periods


Swale 1 - Nassau


Swale 2 – Mirror Lake


Swale 3 - Admiral


Curb and Gutter 1 - Dawson


Curb and Gutter 2 - Darwin


Field Methods

Flow-weighted samples

Continuous rainfall and discharge

Followed FDEP SOPs


Quantity Results

Rainfall vs. Percent Runoff

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 0.5 1 1.5 2 2.5

Rainfall, in.

Pe

rce

nt

Ru

no

ff


Quantity Results

Average runoff coefficients were 58% lower at swale sites

Three times as much rain without runoff at swale sites

Annual runoff difference in total flow volume is approximately 5 times lower at swale sites

Rainfall vs. Percent Runoff

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 0.5 1 1.5 2 2.5

Rainfall, in.

Pe

rce

nt

Ru

no

ff


Results

93% lower TN load

83% lower TP load

95% lower TSS load

93% lower BOD load

Physical removal drives concentration reductions

Infiltration in swales drives volume reductions

Pollutant loads are reduced by both mechanisms


Implications – Local Scale Matters


Town of Melbourne Beach Challenges

Facing large TMDL goal

Lack of real estate for improvements

Expensive cost of property acquisition

Regional projects difficult

Crowned median, grassed edging

Impervious areas directly connected


Sunset Blvd Project Elements

1,000 LF median bioretention swale

Use of curb and flumes to protect median

Pervious pavers at median ends

Native plants used, especially on west end with higher groundwater table

Areas in front of lots graded for rain garden at resident’s request

Normal Flow.

Overflow during extreme events.


West End

Pre and Post

Construction


East End

Pre and Post

Construction


Sunset Blvd Performance

Town received approximately 8 inches of rainfall October 7 - 9, 2011

Visual monitoring performed

No runoff observed


Questions


Regulatory Issues


Why Use Low-Impact Development and

Green Infrastructure?

Lower Costs

Better for Space-Constrained Sites

Improved Pollutant Removal Efficiency

Net Improvement

Multiple Benefits


What Is the Resistance to LID/GI?

Maintenance

Perception

Inertia

Regulatory Acceptance (Reasonable Assurance)

Land Development Regulations


Helping with Regulator Acceptance


Starting Point


Targeting Most Likely Practices

Stormwater reuse

Bioretention

Green roofs

Swales

Compost filters

Tanks/vaults

Porous pavement

Soil amendments

Fertilizer control

Drip irrigation

Florida-friendly yards

Curb elimination

Disconnected

impervious areas

Reduced street width

Cisterns and rain

barrels


Calculating Effectiveness

Less monitoring data available

Effectiveness influenced by local hydrology and high groundwater tables

Continuous simulation needed for some practices

LID practices often not used for full attenuation/treatment


-6

-5

-4

-3

-2

-1

0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Avera

ge D

ep

th t

o W

ate

r (f

eet)

Average Depth to Water at USGS Well 270959082203003

Achieving Simplicity and Flexibility


Shallow Bioretention


Grassed Conveyance Swale


Other Reasonable Assurance Considerations

Design Considerations and Requirements

Design Procedure

Construction

Operation and Maintenance


Questions


Local and

Programmatic

Issues


Local and Programmatic Issues

• Reconciling Land Development Regulations/Code changes

• Maintenance Responsibilities/Concerns

• Liability Issues….should lawyers design stormwater and roadway, walkway projects?

• Synergy With Other Programs


Reconciling With Existing

Codes

Need to determine what aspects of

your existing codes are:

– in direct conflict with,

– silent on or

– lead to confusion on

implementation of an LID program!

And resolve them!


Conflicts with Land Development Regulations

Pavement Requirements

Roadway Widths

Curb and Gutter

Turf Grass Requirements


Opportunities within Land Development

Regulations

Landscape Buffers

Medians

Open Space Requirements

Non-Roadway Pavement

Sidewalks

Irrigation Requirements


Maintenance Concerns

LID facilities are new, haven’t maintained them before

– Longevity?

– Costs?

Need training and may need equipment

Often eliminate trees for ease of mowing/maintenance

Landscaping needs maintenance anyway…does it really cost

more to maintain if it’s LID? Or does another department

maintain “landscaping”? A question of who pays/budgets?

Need budget process that increases for new CIPs…vs “Keep

next years budget request flat or X% lower” ??? Is there a

disconnect here????

Green infrastructure serves many functions: aesthetics,

shade, rainfall interception, buffer, etc….. Need integrated

cross department budget


Maintenance Gets Shortchanged

Just Mowing is Sometimes Hard


Liability Concerns

Women in high heels are thought to be a problem/impediment to pervious pavers

Governments seem particularly risk averse. Government lawyers seem to say its cheaper to pay than to defend against litigation. This begets more litigation.

PF Chang’s changed City of Sarasota attitude. Now pavers are OK.


Notice the difference in

gaps between

impervious and

pervious pavers

Both pavers underlain with storage

reservoir

Women in high heels and their lawyers are

thought to be a problem


SYNERGY WITH OTHER

PROGRAMS

Transportation/Roadway Projects – Opportunity to incorporate retrofits, ie bioswales, pervious parking,

green infrastructure

– Incorporating traffic circles can reduce emissions including nitrogen oxides by 30% (nitrous oxide emissions by 21-44 percent) (Insurance Institute for Highway Safety)

– More walkable communities

– 2 lane Honore with traffic circles -85% of capacity of 4 lane with stop lights

Community Redevelopment Agencies – Englewood CRA

– Palmetto CRA

Review your CIP… look for opportunities for incorporating LID components.


Traffic Circles Reduce NOx Emissions

by 30%

Honore Ave Sarasota


Tampa Bay Area Nitrogen Loads

“Mobile sources have a disproportionately higher contribution than power plants to atomospheric nitrogen deposition to Tampa Bay.”

Over the watershed Nox emissions from mobile sources were responsible for 4 times more NOx than power plants.

Traffic circles reduce by 30%

17%

40%

11%

3%

3%

1%

25%

Total Nitrogen Loading to Tampa Bay in 2002

Direct AtmosphericDeposition

Indirect AtmosphericDeposition throughStormwater

Domestic PointSource

Industrial PointSource

Groundwater andSprings

Material Losses

Non-point Source(Stormwater fromOther)

AD = 57% TN Loading


Before Traffic Circle


After Traffic Circle on Ringling Blvd


Before Bioswale/Traffic Circle

Ringling Blvd Sarasota Discharging

Untreated Runoff Into Sarasota Bay


Bioswale on Ringling Blvd in the ROW


Bioswales in Honore Ave ROW

Saved 17 acres

of trees + cost of

a pond


Tree Canopy Rainfall Interception

California study showed 27% losses in

gross precipitation reaching the ground

with oak trees.

Placing bioswales in the ROW saved

17 acres of trees by eliminating need

for treatment pond.

Sidewalk was meandered around

these trees thereby preserving them.

Maintenance staff didn’t like

boardwalk over the ditch…..hard to

maintain the ditch.

So preservation and/or planting trees

can be part of your LID/Compliance

Program.


More Walk Able Communities?

4 lane with stop

lights nearby

New

2 Lanes with traffic circles on

Honore Sarasota

4 lane with traffic light nearby

LID fosters more walk able places


Retrofitting/Infill/Redevelopment

Andres Duany: “direct

development to where

you want it and can

accommodate it with

infrastructure, etc.”

Good local program

can use LID/Green

Infrastructure to

encourage

development where

you want it!


City of Palmetto Example


Before LID Project


After LID Project


After LID- Aerial View

Contains no stormwater conveyance

piping, zero discharge up to 10-25yr

storm


Directing Development


City of Palmetto Development Incentives

Parking

Stormwater treatment for roof area

Green street ambiance

Cash incentives for using LID

onsite offered by CRA


Other Incentives

Decreased Review Time

Reduction of Stormwater Utility Fee

Others?


Off Street & On-Street Parking


On Street Parking


Stub outs for roof

drains from future

building

Stormwater from New Building


Planters treat roof

runoff from future

adjacent building

Biofiltration Planter Boxes Treat Roof Runoff


Green Street Ambiance


Summary

LID As Part of Your Compliance Plan

Reconcile with local codes & planning regulations

Better integration of planning, construction, and budgets across departments

Synergy with other programs

– Transportation

– Utilities

– Parks

More gobal view

– Trees/vegetation = source control

– Traffic circles = source control

Improve maintenance training, equipment, methods


Questions


Excerpts from MS4 Permitting Resource Manual

1. Each section of the Land Development Code should be reviewed to identify possible impediments to using newer, more sustainable techniques such as “Low Impact Design” or “LID”. (page 19)

2. Does your community’s comprehensive plan and land development regulations promote the use of low impact design principles such as minimizing clearing, minimizing imperviousness, allowing the use of swales or pervious pavements or greenroofs, etc? (page 18)

3. Do we have adequate resources and equipment to properly maintain our stormwater management system? (page 15)


Excerpts from MS4 Permitting Resource Manual

4. Do we have staff that is trained and

knowledgeable about maintaining the various

types of stormwater BMPs and the components

of our stormwater management system (page

15)

Documents

LID and Green Infrastructure - Benefits and Practices · Transportation/Roadway Projects – Opportunity to incorporate retrofits, ie bioswales, pervious parking, green infrastructure