Treatment of storm water generated from highways
-
Upload
sooraj-garg -
Category
Environment
-
view
190 -
download
0
Transcript of Treatment of storm water generated from highways
Sooraj Garg
Department of Civil Engineering
SV National Institute of Technology
Surat 395007
Introduction
Storm water contamination
Causes of Storm water pollution
Effects of Storm water pollution
Storm water treatment
◦Green Infrastructure
◦ Low Impact Development
Factors affecting storm water treatment
Stormwater is water that originates during precipitation events and snow/ice melts, Stormwater is also a resource and ever growing in importance as the world's human population demand exceeds the availability of readily available water
With increasing areas of impervious surfaces (such as
roads, parking lots, and rooftops) in urbanized locations,
more storm water cannot infiltrate into the soil and finally
becomes runoff.
Increased storm water runoff creates two problems: increase
in the rate and volume of runoff, and increase in the variety
and concentration of pollutants contained in the runoff.
Source Arnold and Gibbons(1996), Impervious Surface Coverage
When it rains, runoff from roads and highwaysfrequently washes harmful pollutants into nearbyrivers, streams, and lakes because the surface of roadsis impervious, meaning that water cannot pass throughit.
In a natural environment, 50% of the rain fall isabsorbed in the ground, 40% is evapotranspirate and10% runs off
In an area of 75%-100% impervious surface (such asmany urban areas) 15% of the water is absorbed in theground, 30% is evapotranspiration and 55% runs off.
When it rains, runoff from roads and highways frequently washes
harmful pollutants into nearby rivers, streams, and lakes because
the surface of roads is impervious, meaning that water cannot
pass through it. Therefore, rain that falls on roadways is not able
to soak into the ground as it would naturally.
Storm water generated from highways is most commonly
contaminated by dirt, oil, grease, toxic chemicals, heavy metals,
road salts, nitrogen and phosphorus, pathogens, and trash.
These materials are deposited on roadways as a result of ordinary
traffic activities, such as fluid leakage and the wear and tear of
vehicle parts.
For example, brake pad wear is a source of copper and zinc,
which are the metals most commonly found in highway runoff.
Changes in land use that increase impervious cover lead to
flooding, erosion, habitat degradation, and water quality
impairment.
Everyday activities such as driving, maintaining vehicles
and lawns, disposing of waste, and even walking pets often
cover impervious surfaces with a coating of various harmful
materials.
Construction sites, power plants, failed septic systems,
illegal discharges, and improper sewer connections also
contribute substantial amounts of contaminants to runoff.
Sometime sewer overflows, septic tank leakage also causes
pollution.
This pollution, in turn, impacts important natural resources
as well as other, equally important activities such as
commercial and recreational fishing, swimming, and
boating.
Flooding and Property Damage
Siltation and Sedimentation
Harm to Aquatic Life
Human Illness
Impacts to Drinking Water Supply
Aesthetic Losses
Basic Principal is to prevent pollutants from entering the water in
the first place
In case of Storm Water, we need to ensure that surfaces through
which stormwater run-off passes over should as far as possible be
free from solids and other wastes.
Structural Method
◦ Treatment systems
◦ Erosion and sediment controls
◦ Vegetated volume reduction devices
Typical structural methods are include grassy swales, infiltration
trenches and basins, sand filters, Bio-retention cells, wet and dry
retention ponds, constructed wetlands, and porous pavement.
Non Structural Method
◦ Impervious cover minimization
◦ Land-use planning
◦ Conservation of natural areas
Some Best Management Practices, such as green
infrastructure, Low Impact Development however, are
more effective than others, because those BMPs that
are infiltration-based also help maintain or restore the
natural hydrology of the watershed.
Green infrastructure (GI) can be defined as the natural
and man-made landscapes and features that can be used
to manage runoff.
Examples of natural green infrastructure include
forests, meadows and floodplains.
Examples of man-made green infrastructure include
green roofs, rain gardens and rainwater cisterns.
Green infrastructure replicates the natural functions of
a landscape by integrating functions like storage,
detention, infiltration, evaporation, and transpiration, or
uptake by plants.
Bio swales or Grassed swales◦ Bioswales are vegetated, mulched, channels that
provide treatment and retention
◦ Vegetated swales slow, infiltrate, and filter stormwater flows
Rain gardens◦ it is a planted depression or a hole that allows
rainwater runoff from impervious urban areas.
◦ It reduce the rain runoff by percolating or consuming rain water
Wetlands◦ These can be work like constructed wetland
Source NRDC Report 2011: Storm Water
Source NRDC Report 2011: Storm Water
LID employs principles such as preserving and recreating natural landscape features
Minimizing effective imperviousness to create functional and appealing site drainage that treat stormwater as a resource rather than a waste product
Example of LID are Bio-retention facilities, rain gardens, vegetated rooftops, rain barrels, and permeable pavements.
Objectives of LID are Preserve and recreate natural landscape features, Reduce effective impervious cover, facilitate detention and infiltration opportunities.
LID works on the natural principal of trap and treat the runoff.◦ Physical - increases interception, infiltration, and
evapotranspiration; facilitates sediment removal, filtration, and volatilization; stabilizes soils to reduce sedimentation and erosion
◦ Chemical - facilitates adsorption, ion exchange, and organic complexion.
◦ Biological - increases transpiration, nutrient cycling, direct uptake, and microbial decomposition.
Low impact DevelopmentGreen Infrastructure
LID is a subset of practices/approaches within green infrastructure.
Storm water is treated as resource rather than a waste product
Example of LID are Bio-retention, Rain barrels, Permeable pavement etc.
Green infrastructure
generally refers to a
broader, big picture view of
BMPs
Storm water is treated as
waste product
Example of GI are Bio-
Swales, Rain Garden,
wetland etc.
Traffic volume
Roadway design
Surrounding land use
Regional climate
Accidental spills
Frequency of Rainfall
For Example-
roadways carrying an average of 30,000 vehicles per day may produce runoff with two to five times the pollutant levels found in runoff from rural, less-traveled highways or roadways in arid areas.
Title-“The Design of a Bioretention Area to Treat HighwayRunoff and Control Sediment.”
Site Location “Southern California along State Route 73”.
The Best Management Practices (BMPs) includes twopretreatment devices to help remove litter and sediment
Storm water runoff is ponded to a depth of 150 mm (6 in).The ponding area will be planted with Creeping Wild rye,Salt Grass, Mexican Rush, and Clustered Field Sage.
The bioretention area consists of a 75 mm organic layer, a 1.2 m planting soil layer, a 0.3 m sand layer, and a 0.3 m gravel layer with a PVC under drain system.
(The California Department of Transportation Report: The California Department of Transportation)
(The California Department of Transportation Report: The California Department of Transportation)
In urban areas, Storm water is a major source of pollution of surface water bodies.
In rural areas agriculture runoff is a big problem due to excess use of chemical fertilizers and pesticides.
Some European and American countries have taken a step towards the treatment of storm water generated from highways, by using of some techniques like rain garden, bioretention and wetlands.
To support this report I studied one case study on Bioretention titled “The Design of a Bioretention Area to Treat Highway Runoff and Control Sediment.”
Treatment of storm water is limited to the developed
countries, in developing countries like India, there is no
scope of treatment of storm water some suggestions are
following that I conclude on the basis of this report –
◦ We can provide a vegetable layer along our water bodies.
◦ Some onsite treatment can be provided like filtration, wetland
etc.
◦ We can plant vegetables along the highways so that they
reduce the runoff
Davis P.A. and Hsieh C., 2003, Evaluation of Bioretentionfor Treatment of Urban Storm Water Runoff, World Water & Environmental Resources Congress, pp 1-8.
Kayhanian M., Singh, A., Suverkropp C., and Borroum S. (2003), Impact of Annual Average Daily Traffic on Highway Runoff Pollutant Concentrations, J. Environ. Eng., 129(11), 975–990.
Khan, S., Lau, S., Kayhanian, M., and Stenstrom, M. (2006), Oil and Grease Measurement in Highway Runoff—Sampling Time and Event Mean Concentrations, J. Environ. Eng., 132(3), 415–422.
NRDC, September 2011, After the Storm, “How Green Infrastructure Can Effectively Manage Stormwater Runoff from Roads and Highways”.
Web Sources◦ http://water.epa.gov/infrastructure/greeninfrastructure/index.cf
m◦ https://www.teachengineering.org/view_lesson.php?url=collectio
n/usf_/lessons/usf_stormwater/usf_stormwater_lesson02.xml