Moving LID to the Mainstream

Annette Lucas, PE(919) 807-6381

annette.lucas@ncdenr.gov

NC Division of Energy, Mineral and Land ResourcersStormwater Program

New LID resources: works in progress

Existing LID resourcesA status report on LID in NC

Image: NC LID Guidebook

• Hydrology

• Site Assessment

• Planning

• BMPs

• Construction

• Case Studies

Existing Resource #1: LID Guidebook for NC

Certified individuals: 112

Existing Resource #2: NC LID Cert Program

TOPICS: BMPsPolicy AnalysisCase StudiesEconomicsDesign exercises

Image: NC LID Guidebook

Existing Resource #3: ExamplesLocal Government Programs

Map: www.learnnc.org

Counties: Pender, Brunswick, New Hanover, Onslow, Pender, WakeMunis: Cape Carteret, Cedar Point, Huntersville, Midland, Wilmington *

* This is only a partial list.

Tonbo Meadows, WilmingtonMeadow & woods preservedMinimized gradingRain gardens

Images: NC LID Guidebook

Successful LID Projects

Whole Foods, North RaleighDischarges LESS after development than before.

Photos: www.sandec.com

Wilkes Co. Rest Area

All stormwater from the site is infiltrated or captured and reused.

Photos: www.ncdot.gov

Status Report: How far is LID from the mainstream?

My stormwater reviews for the past 7 years:

>1,000 projects

5 were LID (< 0.5%)

Goal: Get LID to the Mainstream

Scenarios:

1,000 projects

112 would be LID (11.2%)500 would be LID (50%)LID considered as an option on EVERY project.*

* NOTE: LID will not be required.

LID considered on every project… HOW?

NEW RESOURCES:LID definition

Storm-EZ tool

BMP Manual Updates

LID Education

NC LID Guidebook definition:

LID creates a landscape that mimics the natural hydrologic functions of

infiltration, runoff, and evapotranspiration.

1.

Pre‐

& post‐

development rainfall  fates are a close match for the 

90th

percentile storm event.  

2.

The integrity of surface waters is  maintained (hydrology, flows and  structure).

A development is LID when:

What are “RAINFALL FATES?”

Before development, there are two

rainfall  fates:

1.

Runoff 2.

LI fates:   Infiltration, ET, EvaporationPost‐filtration discharge (bioretention

and sand filter underdrains)

After development, we add a third

fate:

3.

Treated runoff (wet pond/wetland)

Photo: www.nowiknow.com

The “Conventional”

Approach:All SW directed via pipes to a wet pond

Before: 

Runoff

+

Infiltration, ET,  Evaporation

After: 

Treated Runoff+

Infiltration, ET, Evaporation

One way to be LIDBefore: 

Runoff

+

Infiltration, ET,  Evaporation

After: Runoff +

Infiltration, ET,

Evaporation

Another way to be LIDBefore: 

Runoff

+

Infiltration, ET,  Evaporation

After: Runoff +

Infiltration

Another way to be LID

Before: 

Runoff

+

Infiltration, ET,  Evaporation After: 

Runoff +

Infiltration,

Post‐ Filtration Discharge, 

ET,

Evaporation

Do the pre‐

and post‐

LI Fates have to  be a perfect match for ALL projects?

No, there will be some leeway,  particularly for dense sites, tight  soils & high water tables.

The “Leeway”

will probably consist of  trading out a portion of LI Fates for 

Treated Runoff.

How are we going to figure what  happens to all of those raindrops?

• Excel• Permitting tool• Hunter Freeman,

PE, Withers and Ravenel

• User inputs data about pre‐

and post‐ dev land uses and SW practices.

• Uses SCS Method to pre‐

and post‐ development rainfall fates.

• Works for both the conventional  “treated runoff”

approach and LID. 

LID will meet all of these programs!

BMP Manual Updates:

Disconnected BUARainwater Harvesting

Green RoofBioretentionInfiltrationSwales

BMP Manual Updates will provide:

These apply to both

LID & conventional development.

• More options

• More credit

• More infiltration designs

Disconnected BUA: (new chapter)

• Two types:  Rooftop drainage &  sheet flow BUA     vegetated areas

• LIF credit via infiltration & ET  depending on soils

• Soil prep needed in D soils

• Centerpiece of LID program

Rainwater Harvesting:

• Drafted by NCSU.

• RWH model estimates  performance.

• New passive drawdown  design    small infiltration 

or bioretention

• LIF credit via ET or  dedicated use

Green Roof:

• Drafted by NCSU & University  of Auckland, NZ

• LIF credit based on the PAW:  plant available water in 

growing medium (ET)

Photos: NCSU-BAE

Bioretention:

• Need to get started

• Promote infiltration via soil prep  and underdrains

• LIF credit based on ET                                 and infiltration

Photos: NCSU-BAE

Photo: Tyner, U of Tennessee

Photo: NCSU-BAE

Infiltration:

• Need to get started

• Test soil infiltration rates

• Soil prep to improve infiltration

• LIF credit based on infiltration  capacity

Swales:

• Need to get started

• Not just for conveyance anymore

• Design as infiltration,                                          wetland or bioretention

• LIF credit based                                                 on design

NEW Educational Resources:

LID Summit – March 26‐27, 2014Organized by the Coastal Federation

LID Technical Workshops starting May 2014Organized by the NCSU Stormwater

Group

LID –

State Technical Review Team:

Withers & RavenelNCSU Stormwater

Group

Coastal FederationLocal governmentsPrivate consultants

Division of Water Resources

YOU?

Why treat

the runoff when you  can eliminate

the runoff?

‐Boyd DeVane