urban runoff - storm water 101
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TRANSCRIPT
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Urban Runoff
Greg GearheartState Water Resources Control
Board
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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
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Hydrologic Changes
Ru
noff
Time
Pre-Development
Urbanization tends to increase storm water runoff:
peak flows
volume
frequency
Post-Develop.
From Haltiner (2006)
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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
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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
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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
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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
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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
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US Waters – Examples
•Rivers, lakes and streams•Tributaries•Territorial seas•Wetlands•Ephemeral washes
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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)
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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
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MS4 – Phase 1
• 26 Regional Water Board Phase I MS4 Permits
• Covering over 1000 entities in CA
• 1 Statewide - Caltrans Permit
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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
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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
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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
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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
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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
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DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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Industrial Facilities
DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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Industrial Facilities
DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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Industrial Permit
• Over 500 Standard Industrial Codes (SIC) regulating specific industries
• Landfills, auto dismantlers, refineries, plastic products, etc.
• Plastic
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DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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Construction
DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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Construction
DRAFT Program report cards developed by Rafael Maestu in the Office of Research, Planning and Performance
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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
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The Construction Stormwater Program
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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.
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+
+
=Construction WQ threats
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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
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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
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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)
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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.
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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
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Post-Construction Impacts
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Post-Construction Standards
• Design to mimic pre-development water balance
• Preserve existing time of concentration
• Protect channels
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After Lane (1955) as cited in Rosgen (1996)
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Channel Changes Associated with Urbanization
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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
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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
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Ideal Soil Structure for Plant Growth
Mineral45%
Organic Matter
5%
Water25%
Air25%
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Rain chains and mulch combo
Sacramento
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Greg [email protected]