msu-ceco/aec_v1 · Datasets at Hugging Face

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What is important about time of concentration is that it is used to determine peak discharge.
Runoff that travels quickly to the outlet means the peak discharge will happen quickly.
When a watershed undergoes development, the time of concentration is reduced largely because of conventional stormwater management methods.
Not only is more runoff produced because the watershed CN is increased, but curbs, gutters and pipes quickly route the stormwater to the watershed outlet.
A fundamental goal of LID is to increase the time of concentration by disconnecting impervious areas.
For example, instead of rainfall from a parking lot being directed to curb inlets to enter the storm sewer system where it is quickly routed to a stream, LID would encourage infiltrating the rainfall onsite.
This means that none or very little rainfall enters the storm sewer system.
runoff volumes and peaks are reduced and stormwater quality is improved.
When using structural controls, it is best to start in the headwaters of a watershed as controls located in these areas are more effective at protecting streams than controls located at the watershed outlet.
When designing LID-based stormwater management plan, a number of structural controls that use the LID philosophy are available.
These controls vary in size and complexity from small ones suitable for a residential lot to large ones typically used by developers, commercial businesses, and governments.
This publication will examine a few of the more commonly used ones.
Rain gardens are shallow depressions that use a conditioned planting bed and landscaping to filter stormwater.
Rain gardens are typically designed to capture runoff from a 1-inch storm event and infiltrate the rainwater within 24 to 48 hours.
Rain gardens can be planted with trees, shrubs, grasses, and/or flowers.
When choosing vegetation for a rain garden, it is important to use native vegetation.
Native vegetation is acclimated to the local climate and does not require excessive maintenance to survive.
Because rain gardens undergo periods of drought and inundation, it is also important to choose plants that can withstand these conditions.
Figure 6.
Rain gardens may contain trees and shrubs, such as this one at the Coca-Cola Bottling Facility in Lexington, Ky.
Rainwater harvesting is one of the simplest and oldest LID techniques.
With rainwater harvesting, rainwater from roof tops and other impervious areas is collected and stored in rain barrels or even cisterns for future use.
In some cases, excess rainwater is redirected from the rain barrel to a rain garden.
Collected rainwater is often used to wash automobiles, irrigate or flush toilets.
Harvested rainwater is not potable SO it is not safe to drink.
Riparian buffers are vegetated areas adjacent to streams.
Typically comprised of three vegetation zones, riparian buffers provide many benefits to stream systems.
The roots of riparian vegetation help hold streambank soils in place, protecting the banks from high flows, and thereby reducing erosion.
Riparian vegetation provides the stream with shade which helps control temperature and algal growth while improving dissolved oxygen levels.
Leaves and twigs from riparian vegeta-
Figure 7.
Rain barrels are ideal for collecting rain water from roof tops for future use.
tion provide aquatic organisms with a source of food while birds and animals consume fruits and nuts produced by the plants.
Riparian buffers also improve stream water quality by filtering sediment, nutrients and other pollutants from overland flow.
The effectiveness of a riparian buffer is strongly linked to its width, and the required buffer width is strongly linked to topography, land use, hydrology, and the constituents of concern.
If the buffer is too narrow, it will not meet the site objectives.
For sediment removal, a buffer width of 25 feet may be sufficient but a width of 100 feet may be needed for nitrate removal.
Socioeconomic factors will also play a role in determining the appropriate buffer width, particularly in urban areas.
A green roof, also called a landscaped roof or rooftop garden, consists of a soil media and plants.
These systems can be rather simple consisting largely of hardy groundcover plants such as sedums or more complex with a park-like setting.
The simpler green roof design is called an extensive system while the more complex one is an intensive system.
Rainwater that falls on green roofs undergoes evapotranspiration, which reduces runoff volumes and peak flows.
Evaporation combined with shading from the plants helps cool the roofs.
Studies have shown that temperatures on green roofs are much cooler than the surrounding air temperature.
When designing a green roof, it is important to determine what type of additional structural support may be needed to support the extra weight.
Extensive systems are lighter than intensive ones, and as such, require less additional structural support.
Like rain gardens, native plants should be used.
Vegetation on green roofs is exposed to the wind, sun, ice and other harsh conditions with little or no relief.
Care must be taken to choose hardy plants.
Permeable pavement is an asphalt or concrete paving surface specially mixed with fewer fine particles which creates more void spaces.
In addition to continuous type surfaces, interlocking concrete or brick pavers are also used.
Permeable pavement consists of a paving course, filter course, stone reservoir, and filter fabric layer.
Water easily flows through permeable pavement and infiltrates the underlying soils.
The common types of permeable pavement are pervious concrete, porous asphalt, interlocking concrete pavers, concrete grid pavers, and plastic reinforced grids filled with either grass or gravel.
Permeable pavement is most commonly used in parking lots, driveways, walking paths, residential streets, and other such locations where the traffic volumes are light.
This LID technique is effective at reducing peak flows and total runoff volumes and has shown some promise at removing pollutants such as heavy metals and nutrients from runoff.
Due to concerns over clogging, permeable pavement is not recommended for use in areas with high sediment loads.
Bioswales are shallow, wide, low-sloped channels, which are lined with vegetation or rock.
Used in lieu of pipes, bioswales transport runoff to the storm sewer system or to receiving waterbodies.
As such, bioswales are ideal for use alongside roadways or within parking medians.
Bioswales are designed to promote infiltration by slowing down runoff.
They also improve water quality via filtration and settling.
The depth of flow should be less than the height of the vegetation or rock.
Figure 9.
Green roofs, such as this one, help reduce runoff volume and reduce the building's energy usage.
Figure 10.
Permeable pavement, such as these interlocking clay brick pavers, is ideal for light traffic areas such as parking lots.
Figure 11.
Parking medians, such as this one at the Sanitation District 1 parking lot in Northern Kentucky, are ideal locations for bioswales.
Photo courtesy of Jim Hanseen of EcoGro.
Figure 12.
Stormwater wetlands provide habitat for wildlife in addition to improving stormwater quality.
Stormwater wetlands or constructed wetlands consist of shallow pools and rooted vegetation.
In addition to the shallow pools, stormwater wetlands generally have two deep pools: one located at both the inlet and one at the outlet of the wetland.
The deep pool at the inlet acts like a forebay allowing particulates to settle out of suspension.
At the outlet, the deep pool helps prevent clogs by keeping vegetation from growing near the outlet.
Stormwater wetlands are effective at pollutant removal.
Similar to natural wetlands, settling, filtration and biological uptake are the three primary methods for removing pollutants in stormwater wetlands.
Stormwater wetlands also provide habitat though the level of biodiversity may be less than natural wetlands.
While stormwater wetlands are similar to natural wetlands, it is important to note that natural wetlands should not be used for stormwater treatment.
Routing stormwater into a natural wetland can alter its hydrology thus affecting the vegetation.
One of the biggest concerns with LID techniques is the cost.
Will it cost more to design, implement and maintain LID controls as opposed to using conventional stormwater methods?
The answer is that it depends.
Costs are site specific.
Factors such as existing soil conditions, topography, land availability,
vegetation, stormwater control size and complexity, and desired maintenance level will drive costs.
With regards to maintenance costs, vegetation management is usually the most costly item, SO selecting low-maintenance vegetation is important.
It is also important to prevent large sediment loads, such as those associated with construction activities, and litter from impacting LID controls.
Sediment is the number one enemy of LID controls; it causes clogging and shortens the control's useful life.
A forebay, which is a small, cleanable pool located at the inlet of the LID control, is often used to prevent incoming sediment and debris from clogging LID controls.
Stormwater management is an important issue for developing communities.
While conventional stormwater management techniques are effective at routing stormwater from impervious areas to receiving water bodies, they are not effective at reducing runoff volume or improving runoff water quality.
LID techniques, on the other hand, promote infiltration and evapotranspiration in an effort to reduce runoff volumes and improve runoff water quality.
And unlike conventional stormwater management, which often uses a large control structure at the outlet of a development such as a shopping center or neighborhood, LID promotes the use of many small control structures spread throughout the watershed.
Resource Protection and Structural Controls
Reducing Stormwater Pollution
Building a Rain Barrel
Riparian Buffer Planting
This is important for two reasons.

What is important about time of concentration is that it is used to determine peak discharge.

Runoff that travels quickly to the outlet means the peak discharge will happen quickly.

When a watershed undergoes development, the time of concentration is reduced largely because of conventional stormwater management methods.

Not only is more runoff produced because the watershed CN is increased, but curbs, gutters and pipes quickly route the stormwater to the watershed outlet.

A fundamental goal of LID is to increase the time of concentration by disconnecting impervious areas.

For example, instead of rainfall from a parking lot being directed to curb inlets to enter the storm sewer system where it is quickly routed to a stream, LID would encourage infiltrating the rainfall onsite.

This means that none or very little rainfall enters the storm sewer system.

runoff volumes and peaks are reduced and stormwater quality is improved.

When using structural controls, it is best to start in the headwaters of a watershed as controls located in these areas are more effective at protecting streams than controls located at the watershed outlet.

When designing LID-based stormwater management plan, a number of structural controls that use the LID philosophy are available.

These controls vary in size and complexity from small ones suitable for a residential lot to large ones typically used by developers, commercial businesses, and governments.

This publication will examine a few of the more commonly used ones.

Rain gardens are shallow depressions that use a conditioned planting bed and landscaping to filter stormwater.

Rain gardens are typically designed to capture runoff from a 1-inch storm event and infiltrate the rainwater within 24 to 48 hours.

Rain gardens can be planted with trees, shrubs, grasses, and/or flowers.

When choosing vegetation for a rain garden, it is important to use native vegetation.

Native vegetation is acclimated to the local climate and does not require excessive maintenance to survive.

Because rain gardens undergo periods of drought and inundation, it is also important to choose plants that can withstand these conditions.

Figure 6.

Rain gardens may contain trees and shrubs, such as this one at the Coca-Cola Bottling Facility in Lexington, Ky.

Rainwater harvesting is one of the simplest and oldest LID techniques.

With rainwater harvesting, rainwater from roof tops and other impervious areas is collected and stored in rain barrels or even cisterns for future use.

In some cases, excess rainwater is redirected from the rain barrel to a rain garden.

Collected rainwater is often used to wash automobiles, irrigate or flush toilets.

Harvested rainwater is not potable SO it is not safe to drink.

Riparian buffers are vegetated areas adjacent to streams.

Typically comprised of three vegetation zones, riparian buffers provide many benefits to stream systems.

The roots of riparian vegetation help hold streambank soils in place, protecting the banks from high flows, and thereby reducing erosion.

Riparian vegetation provides the stream with shade which helps control temperature and algal growth while improving dissolved oxygen levels.

Leaves and twigs from riparian vegeta-

Figure 7.

Rain barrels are ideal for collecting rain water from roof tops for future use.

tion provide aquatic organisms with a source of food while birds and animals consume fruits and nuts produced by the plants.

Riparian buffers also improve stream water quality by filtering sediment, nutrients and other pollutants from overland flow.

The effectiveness of a riparian buffer is strongly linked to its width, and the required buffer width is strongly linked to topography, land use, hydrology, and the constituents of concern.

If the buffer is too narrow, it will not meet the site objectives.

For sediment removal, a buffer width of 25 feet may be sufficient but a width of 100 feet may be needed for nitrate removal.

Socioeconomic factors will also play a role in determining the appropriate buffer width, particularly in urban areas.

A green roof, also called a landscaped roof or rooftop garden, consists of a soil media and plants.

These systems can be rather simple consisting largely of hardy groundcover plants such as sedums or more complex with a park-like setting.

The simpler green roof design is called an extensive system while the more complex one is an intensive system.

Rainwater that falls on green roofs undergoes evapotranspiration, which reduces runoff volumes and peak flows.

Evaporation combined with shading from the plants helps cool the roofs.

Studies have shown that temperatures on green roofs are much cooler than the surrounding air temperature.

When designing a green roof, it is important to determine what type of additional structural support may be needed to support the extra weight.

Extensive systems are lighter than intensive ones, and as such, require less additional structural support.

Like rain gardens, native plants should be used.

Vegetation on green roofs is exposed to the wind, sun, ice and other harsh conditions with little or no relief.

Care must be taken to choose hardy plants.

Permeable pavement is an asphalt or concrete paving surface specially mixed with fewer fine particles which creates more void spaces.

In addition to continuous type surfaces, interlocking concrete or brick pavers are also used.

Permeable pavement consists of a paving course, filter course, stone reservoir, and filter fabric layer.

Water easily flows through permeable pavement and infiltrates the underlying soils.

The common types of permeable pavement are pervious concrete, porous asphalt, interlocking concrete pavers, concrete grid pavers, and plastic reinforced grids filled with either grass or gravel.

Permeable pavement is most commonly used in parking lots, driveways, walking paths, residential streets, and other such locations where the traffic volumes are light.

This LID technique is effective at reducing peak flows and total runoff volumes and has shown some promise at removing pollutants such as heavy metals and nutrients from runoff.

Due to concerns over clogging, permeable pavement is not recommended for use in areas with high sediment loads.

Bioswales are shallow, wide, low-sloped channels, which are lined with vegetation or rock.

Used in lieu of pipes, bioswales transport runoff to the storm sewer system or to receiving waterbodies.

As such, bioswales are ideal for use alongside roadways or within parking medians.

Bioswales are designed to promote infiltration by slowing down runoff.

They also improve water quality via filtration and settling.

The depth of flow should be less than the height of the vegetation or rock.

Figure 9.

Green roofs, such as this one, help reduce runoff volume and reduce the building's energy usage.

Figure 10.

Permeable pavement, such as these interlocking clay brick pavers, is ideal for light traffic areas such as parking lots.

Figure 11.

Parking medians, such as this one at the Sanitation District 1 parking lot in Northern Kentucky, are ideal locations for bioswales.

Photo courtesy of Jim Hanseen of EcoGro.

Figure 12.

Stormwater wetlands provide habitat for wildlife in addition to improving stormwater quality.

Stormwater wetlands or constructed wetlands consist of shallow pools and rooted vegetation.

In addition to the shallow pools, stormwater wetlands generally have two deep pools: one located at both the inlet and one at the outlet of the wetland.

The deep pool at the inlet acts like a forebay allowing particulates to settle out of suspension.

At the outlet, the deep pool helps prevent clogs by keeping vegetation from growing near the outlet.

Stormwater wetlands are effective at pollutant removal.

Similar to natural wetlands, settling, filtration and biological uptake are the three primary methods for removing pollutants in stormwater wetlands.

Stormwater wetlands also provide habitat though the level of biodiversity may be less than natural wetlands.

While stormwater wetlands are similar to natural wetlands, it is important to note that natural wetlands should not be used for stormwater treatment.

Routing stormwater into a natural wetland can alter its hydrology thus affecting the vegetation.

One of the biggest concerns with LID techniques is the cost.

Will it cost more to design, implement and maintain LID controls as opposed to using conventional stormwater methods?

The answer is that it depends.

Costs are site specific.

Factors such as existing soil conditions, topography, land availability,

vegetation, stormwater control size and complexity, and desired maintenance level will drive costs.

With regards to maintenance costs, vegetation management is usually the most costly item, SO selecting low-maintenance vegetation is important.

It is also important to prevent large sediment loads, such as those associated with construction activities, and litter from impacting LID controls.

Sediment is the number one enemy of LID controls; it causes clogging and shortens the control's useful life.

A forebay, which is a small, cleanable pool located at the inlet of the LID control, is often used to prevent incoming sediment and debris from clogging LID controls.

Stormwater management is an important issue for developing communities.

While conventional stormwater management techniques are effective at routing stormwater from impervious areas to receiving water bodies, they are not effective at reducing runoff volume or improving runoff water quality.

LID techniques, on the other hand, promote infiltration and evapotranspiration in an effort to reduce runoff volumes and improve runoff water quality.

And unlike conventional stormwater management, which often uses a large control structure at the outlet of a development such as a shopping center or neighborhood, LID promotes the use of many small control structures spread throughout the watershed.

Resource Protection and Structural Controls

Reducing Stormwater Pollution

Building a Rain Barrel

Riparian Buffer Planting

This is important for two reasons.