Low Impact Development

Adjusting to the New Storm Water Paradigm

What is LID?

• A site-specific, conceptual approach to minimize the detrimental effect of hydromodification

• LID Goal - Mimic the natural hydrologic cycle• Site-specific – Designs will change per locale• Conceptual – Qualitative not quantitative• Approach – Needs to be addressed and included from the

inception of the project• Development – LID requirements are currently focused exclusively

on new developments and significant* redevelopments• Hydromodification – the unnatural redirecting of stormwater

Evolution of Storm Water Treatment Three Main Phases

• Phase I: Conventional Model (pre-70’s)– Collect and ConveyPROBLEM: Point-source pollution, hydromodification

• Phase II: Retention Model, BMPs (80’s and 90’s)– Flow, Volume and Source/Treatment ControlPROBLEM: Hydromodification, maintenance

• Phase III: Low Impact Design Model (2000+)– Mimicking Natural HydrologyPROBLEM: Adequate treatment? Flooding? Implementation?

Involvement?

Progression of Legislation

• Clean Water Act of 1972– Set goals for all national waters to be free of all discharges

causing pollution– Required TMDLs for impaired watersheds

• NPDES Permits (Section 402 CWA)– Storm Water Pollution Prevention Plan– Storm Water Management Plan– Development Standards Plan

• State Board’s Sustainability Resolution (2005-2006)

• NPDES Permits now shifting to LID– Contra Costa County Phase I NPDES Permit (2005)– Stockton Phase I NPDES Permit (Dec. 2007) – Upcoming statewide Phase II NPDES Permit (~ March 2009)

What is LID?

• Site-specific, conceptual approach of developing property to minimize the detrimental effect of hydromodification and pollution

• LID Goal - Mimic the natural hydrologic cycle• Site-specific – Designs will change per locale• Conceptual – Qualitative not quantitative• Approach – Needs to be addressed and included from the

inception of the project• Development – LID requirements are currently focused exclusively

on new developments and significant* redevelopments• Hydromodification – the unnatural redirecting of stormwater

Hydrologic Cycle

Natural Infiltration

Our Mokelumne

Example of Erosion caused by Hydromodification

Natural Balance of Erosion and Deposition

After Lane (1955) as cited in Rosgen (1996)

Environmental Benefits of LID

• Cost Effective - less treatment, less conveyance, less maintenance, less fines, etc.

• Mitigates downstream flooding, erosion and aggradation

• Helps control water quality

• Preserves stream base for riparian ecosystems

• Helps recharge groundwater

• Preserves natural temperatures in receiving waters

• Multifunctional: landscaping, aesthetics, native vegetation, social benefits, open space use, etc.

• Resilient and adaptable to various climates

Functional Benefits of LID

• Treats first flush runoff– Majority of contaminants

• Treats common small/medium-size storm– Majority of storms

• Design includes overflow for large storms– Conventional MS4 used as back-up

• Aesthetically pleasing

• Easy to maintain

Ways to Mimic Natural Hydrology

• Know your natural hydrology!• Soil quality improvement• Native and drought tolerant vegetation• Trees• Maximize pervious surfaces• Disconnect impervious surfaces from storm

drain - disconnect downspouts, rain barrels, • Bioretention – Rain Gardens, swales• Green Roofs?

LID Examples

The Big Challenge - Implementation

• Statewide Quantitative Standards– TMDLs– Sizes of IMPs– Regulator-based

• Local Qualitative Standards– Permittee-based– Matching local conditions

• The Main Need – Local Involvement– Planning Department, Engineering Firms,

Construction Firms, Landscape Architects, Environmental Consultants, Field Technicians…

Current Implementation Approaches for LID

• Contra Costa County - C3 Guidebook 4th Edition– IMPs for 4% of impervious surface– Present challenge is to find proper soil type– www.cccleanwater.org/newdevelopmentc3/

• Santa Barbara’s New NPDES Permit– http://www.santabarbaraca.gov/Resident/Community/Creeks/Storm_

Water_Management_Program.htm

• City of Stockton’s new NPDES Permit– Revision of SWQCCP currently in progress– Stakeholder meetings in progress– www.stocktongov.com/mud/General/stormwater/SQCCP.cfm

• Phase II NPDES Permits– Expected March 2009

Recent Funding Opportunity – Proposition 84

• Matching Grants for sustainable, long-term water quality projects which reduce and prevent stormwater contamination of rivers, lakes and streams

• LID projects will take priority for grants• 20% match for most cities and towns in delta

area• $250,000 to $500,000 grants per project• 2 Phases of grants

http://www.waterboards.ca.gov/water_issues/programs/grants_loans/prop84/index.shtml

New Developments?! Where? Will that really make a difference?

• We have to start somewhere

• Retrofitting is too costly

• Use of grant money may show the success of LID and direct projects to existing developments

LID Opportunities for WGR

• Expert knowledge of NPDES requirements

• Ensuring clients with LID compliance

• Knowledge of local soils and hydrology

• Filling in needs to facilitate implementation

• Geographic Informational Systems (GIS)

• Offering compliant LID design concepts

• Constructing and maintaining LID sites

Closing Comments

• Unexplored Territory Ahead

• Opportunity for Sustainable Change

• A whole new market

• Share Ideas. Let’s go forward intelligently. Foster awareness.

• Goal – See WGR as the Central Valley Leader in innovative LID solutions!

Thanks for Listening!

Any Questions or CommentsPlease call Chris @ (209) 334-5363 ext. 214

WGR Southwest, Inc.315 W. Pine St.Lodi CA 95240

Restoring Soil Function

Soil Health

Riparian Zone