Storm Water Management and Erosion/Sediment Control

• Storm water management reduces quantity, and improves quality, of runoff in the watershed

• Site based approach reduces long term costs to community

Why Storm Water Management and Erosion/Sediment Control?

• Required by EPA Phase II!• Protect health, safety and

welfare• Reduce flood impacts• Reduce impacts to

property• Reduce pollution in

streams, rivers and Lake Erie

Low Impact Development

• Low impact development works at individual sites to reduce surface flows, filter storm water, and disperse storage areas

• Many solutions are lower cost than engineered approaches

Stormwater Topics

• Water Quality• Water Quantity• Stream and Ditch Restoration and

Management• Low Impact Development• Developed vs. Developing Communities

The Basics – Concepts: Water Quantity

• Runoff: amount of precipitation and infiltration

• Travel time: slope, flow depth/length, and roughness

• Peak Discharge: Runoff, Travel Time, Watershed Size, Development Location, Timing of Rainfall, Storage Effect

• Time of Concentration: Time from farthest reach to output point

Water Quantity ctd.

• Impervious Surface: surface with minimal infiltration

Water Quantity ctd.

• Bank Storage: storage and release within stream or ditch bank

• Connection to floodplain is best

• Flat subwatersheds are more sensitive to stormwater increases than those with terrain

Recommended Practices:Water Quantity

Increase Infiltration, Reduce Speed, and Increase Storage (increase travel time) (mimic pre-development conditions):

• Reduce impervious surface, increase perviousness• Improve storage and release on-site• Increase roughness• Decentralize/reduce concentration of flow• Take advantage of bank storage• Connect stream to floodplain

The Basics – Concepts:Water Quality

• Sediments: construction runoff, soil disturbance, stream erosion

• Nutrients: fertilizers, septic/animal wastes

• Bacteria: sewer overflows, septic/animal wastes

• Debris: dumping, sewer overflows

• Hazardous wastes: poor storage, poor separation, inappropriate use of materials

Water Quality ctd.

• BOD – Biological Oxygen Demand

• Nutrients in water ABSORB oxygen as they break down

• Aquatic life suffers

Recommended Practices:Water Quality

• Minimize soil disturbance • Minimize water quantity increases in streams and

ditches • Filter and settle out sediments and contaminants• Vegetate stream and ditch corridors• Improve storage and separation of materials• Maintain septic systems• Prevent illicit discharges and dumping

Stream/Floodplain Restoration• Habitat: vegetation,

temperature, hydrology, water quality

• Stream hydrology: meanders, pools, riffles, floodplain

• Engineering: stream section, relationship to flow patterns of drainage area, floodplain

Oxbow River and Stream Restoration

Agricultural Ditch Enhancement

• Approximate stream morphology: 2-stage or hybrid section

• Minimize “maintenance”• Vegetate

Stormwater Management BMPs• Require Stormwater Pollution Prevention Plans on

development sites• Require developers to control the volume, rate, and quality of

stormwater coming off sites• Require good quality installation, and use of low-maintenance

facilities• Decentralize stormwater collection and conveyance• Minimize stream crossings• Retain and restore natural stream function • Enhance function of existing agricultural ditches

Roles in Storm Water Regulation

• Ohio EPA: Water quality: If disturbing > 1 acre, EPA requires SWPPP

• Local government must address water quantity issues

• SWCDs and watershed groups may be involved in erosion/sediment control, storm water management plan reviews

Low Impact Development (LID)

• Rain Garden• Vegetated filter strip

LID

• Bioretention filters/strips

• Catch basin insert

LID

• Disconnectdownspouts

• Eliminate curb/gutter

LID

• Pervious pavements

LID

• Natural drainage basins (wet ponds with natural edge)

LID

• Green roofs

Examples of LID Projects in Ohio

• Ladue Trails, Geauga County: Bio-retention• Nottingham Woods, Geauga Co.: rain gardens• Sunset Ridge, Geauga: filter strip• Best Buy, Lorain: sand filter• Dollar General Store, Lorain: dry swales• Deer Valley, Lucas County: bio-retention

Advice for Developed Communities

• Update and implement codes for low impact site design options (conservation development, compact development, riparian setbacks)

• Update and implement codes for innovative stormwater techniques (LID, restore stream section, two-stage ditch section, bioretention, grass swales, rain gardens, etc)

• Require provisions for management/maintenance• Improve control of illicit discharges

Advice for Developing Communities

• Plan and map priority conservation areas, priority development areas, riparian and floodplain protection corridors

• Implement codes for innovative site design• Implement codes for innovative stormwater

management• Require management provisions

Stormwater Management Regulations: Two Types

• Construction Runoff Control (AKA Erosion/Sediment Control): Water Quality – Requires SWPPP

• Post-Construction Control: Water Quality AND Quantity – managed through SWPPP and SWMP

Erosion/Sediment Control: How it works

• Requires preparation of a storm water pollution prevention plan (SWP3), or Abbreviated SWP3

• Establishes standards and preferred methods for control of sediment

Erosion/Sed Control: Methods

• Nonstructural : site design and avoidance of disturbance in the first place

• Stabilization: Covering/seeding disturbed areas• Runoff control: Diverting runoff from disturbed areas

(swales, dikes, berms, etc.)• Sediment control measures: collecting sediment and

keeping it on site (silt fences, settling ponds, storm sewer inlet protection)

Post-Construction Stormwater Management : How It Works

• Requires Comprehensive Stormwater Management Plan for activities disturbing soil

• Sets standards for volume, rate and quality of runoff from completed project

• Sets standards for preferred methods and facilities

Post-Construction Stormwater Management: Methods

• Structural practices acceptable to Ohio EPA: wet retention, dry retention, etc.

• Nonstructural: site design, conservation development, minimizing disturbance, riparian/wetland setbacks

• Low impact development practices: rain gardens, grassy swales, etc.

Both Types: Administrative Issues

• Both types must be addressed – together or separate

• Standards and practices must meet minimum OEPA standards

• Should require compliance with State/Federal Regulations

• Must require provisions for maintenance of facilities during and after construction

Administrative Issues continued

• Who will have responsibility for plan review and inspection?

• Who will have responsibility for long-term maintenance of facilities?

• How will long term monitoring be handled?• Erosion/Sed Control - Must have authority to

stop work immediately• Must have provisions for enforcement• Penalties – most are a misdemeanor

Recommended Review Process1) Conceptual Plan Stage (“Sketch Plan”)

-Pre-application meeting-Sketch Plan Submitted-Review on-site: riparian/wetland delineation

2) Preliminary Plan Stage-Preliminary Plan-determine applicability of state/federal regulations

3) Preliminary Improvement Plan Stage-Construction drawings-submit crossing, riparian setback, slope stabilization, stormwater etc plans (as required by regulation)-all permits/approvals in process (required) for final approval

4) Final Plat-record all easements, setbacks, agreements as required by regulation