Urban Runoff - Storm Water 101

Urban Runoff

Greg GearheartState Water Resources Control

Board

Urban Runoff Problems

•Pollution– Beach closures– Water quality impairment– Fish kills– Plastic debris

•Physical alteration of the watershed / water bodies– Stream incision / erosion / deposition– Habitat destruction

Hydrologic Changes

Ru

noff

Time

Pre-Development

Urbanization tends to increase storm water runoff:

peak flows

volume

frequency

Post-Develop.

From Haltiner (2006)

Regulatory Solution

• Stormwater Program– A Clean Water Act-based program– A permitting solution– “Forces” stormwater peg into the

existing hole designed to protect surface waters

– Has evolved over the years to include new tools and connect to TMDLs

Overview of the Clean Water Act

• Federal Water Pollution Control Act of 1972, amended 1977

– NPDES programs

– Permits are a privilege, not a right

– Effluent limits must be both technology and water quality based

• 1987 – added Section 402(p) to CWA covering stormwater

Overview of the Clean Water Act

• All “point sources”

• “Discharging a pollutant”

• Into a “Water of the U.S”

>>>>Must obtain a NPDES (National Pollutant Discharge Elimination System) Permit

What is a Point Source ?

•Point Source– Discharge though a discrete

conveyance into waters of the US•Industrial facilities•Sewage treatment plants•Stormwater from industrial sites and

storm sewers

– Non-point source•Runoff that is not a point source

What is a Water of the U.S ?

•All waters currently used, used in the past, or susceptible to use for interstate commerce including all waters which are subject to the ebb and flow of the tide

US Waters – Examples

•Rivers, lakes and streams•Tributaries•Territorial seas•Wetlands•Ephemeral washes

Stormwater Program Overview

•Municipal Program – urban runoff• Industrial Program – industrial

sector specific runoff•Program Overlap

– Many industrial sites discharge INTO Municipal Separate Storm Sewer Systems (MS4s)

Municipal Stormwater Permits

• Municipal Separate Storm Sewer Systems (MS4s)– Phase I

•Municipalities > 100,000 population

– Phase II•Small municipalities and others

– 9th circuit court decision 1992

MS4 – Phase 1

• 26 Regional Water Board Phase I MS4 Permits

• Covering over 1000 entities in CA

• 1 Statewide - Caltrans Permit

Municipal Permits

• Municipal permits (under Phase I) Municipal permits (under Phase I) are issued by Regional Boards for:are issued by Regional Boards for:

• Municipalities > 100,000Municipalities > 100,000• Contiguous municipalities sharing Contiguous municipalities sharing

a large MS4a large MS4• Small municipalities covered under Small municipalities covered under

Phase II regulationsPhase II regulations

MS4 Phase II – 6 Minimum Program Elements

• Education an Outreach• Public Participation/Involvement• Illicit Discharge Detection and

Elimination• Construction Site Runoff Control• Post Construction Runoff Control• Pollution Prevention/Good

Housekeeping

MS4 – Phase I Issues

• June 19, 2006 - State Water Board released Blue Ribbon Panel Report

• Municipal Discharges - Panel Recommended

• (Action Levels and improve accountability)

• Impaired water bodies and TMDLs are being implemented through MS4 permits

• Over 1000 cities, counties, and other governmental agencies regulated – significant

MS4 – Phase II

• Current permit requires MS4s to enroll and for Rbs to approve SWMP

• About 150 MS4s currently “covered”

• New Phase II permit being drafted

Industrial Stormwater Permits

• Industrial General Permit (SB Order 97-03-DWQ)– Sector/SIC code specific

• Construction General Permit (SB Order No. 99-08-DWQ)– Construction and development

industry– All projects that disturb 1 acre or more

of land must obtain coverage

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

Industrial Facilities

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

Industrial Facilities

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

Industrial Permit

• Over 500 Standard Industrial Codes (SIC) regulating specific industries

• Landfills, auto dismantlers, refineries, plastic products, etc.

• Plastic

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

Construction

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

Construction

DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance

Plastic Debris Program

• ~400 facilities regulated under the industrial general permit (IGP)

• ~3000 facilities statewide that handle preproduction plastic pellets in some manner

• Part of global problem – fate and transport in the environment of plastic is impressive

The Construction Stormwater Program

Construction Activity Threats

• Two-fold – construction projects have the potential to cause impacts to our beneficial uses of water both during and after the project.

• During – potential for sediment erosion discharges.

• After – potential for pollutant export and hydromodification impacts as a result of how the new landscape functions.

+

+

=Construction WQ threats

Who needs coverage

1) All sites that disturb more than one acre

2) All sites that are less than one acre but part of a “larger plan of development”

3) All sites that are thought to be a threat to water quality, as deemed by the appropriate RWQCB

Permit Reissuance Goals

1) Adopt a risk-based permit approach- “not all sites are created equal”

2) Improve “performance” measurement of program

3) Establish standards to avoid, minimize and mitigate post-construction impacts associated with all new and re-development projects triggering the construction activity permit

Program “Performance” Elements

• Certification and training expectations

• Effluent monitoring = feedback for site amd program

• Receiving water monitoring = feedback for “water quality outcome” goals/objectives

• Performance-based post-construction runoff standards (pre = post)

Risk Approach

• Three risk categories• Aimed at sediment transport and

receiving water risk of construction activities “normal distribution” assumption (most projects should not be high risk)

• Incentives/requirements linked to risk.

Direct Erosion / Sediment Control Requirements

• Old model used SWPPP as main vehicle

• New approach to use Rain Event Action Plan (REAP) as primary tool (SWPPP becomes more a master document/library)

• Requirements based on risk• Prevention and planning incentives

Post-Construction Impacts

Post-Construction Standards

• Design to mimic pre-development water balance

• Preserve existing time of concentration

• Protect channels

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

Channel Changes Associated with Urbanization

The future

• Low Impact Development (LID) and Green Infrastructure (GI) represent “natural systems” approach to building better urban landscapes.

• Both aim to protect and/or restore “natural hydrology” and ecological processes

• LID – site and neighborhood scale• GI – community and watershed

scale

Ways to mimic pre-development water balance and Tc

Soil quality improvement (porosity)

Native and drought tolerant vegetation

Trees Permeable pavement Riparian buffers A general reduction of

connected, impervious surfaces in runoff pathways

Bioretention Disconnected downspouts/rain

chains/rain barrels

Ideal Soil Structure for Plant Growth

Mineral45%

Organic Matter

5%

Water25%

Air25%

Rain chains and mulch combo

Sacramento

Greg Gearheart916.341.5892ggearheart@waterboards.ca.gov