STORM WATER

SYSTEM

INTRODUCTION rain and snow melt that runs off surfaces such

as rooftops, paved streets, highways, and parking lots.

As water runs off these surfaces, it can pick up pollution such as: oil, fertilizers, pesticides, soil, trash, and animal waste.

From here, the water might flow directly into a local stream, bay, or lake. Or, it may go into a storm drain and continue through storm pipes until it is released untreated into a local waterway.

In addition, the large impervious surfaces

in urban areas increase the quantity of

peak flows of runoff, which in turn cause

hydrologic impacts such as scoured

streambeds channels, instream

sedimentation and loss of habitat.

The importance of Storm Water System

Human Health:

Stormwater can contain toxic metals, organic

compounds, bacteria, and viruses.

Untreated stormwater is not safe for people to

drink and is not recommended for swimming.

Polluted stormwater can lead to beach

closures for swimming and shellfish harvesting.

It can also trigger toxic algal blooms.

TOXIC ALGAL BLOOMS

Drinking Water:

Untreated storm water discharging to the ground

could contaminate aquifers that are used for drinking

water.

Degraded Water Quality:

Virtually all of our urban creeks, streams, and rivers are

harmed by storm water pollution.

Storm water is the leading contributor to water quality

pollution of urban waterways.

Impaired Habitat: In Washington, urban stormwater

harms and pollutes streams that provide habitat for

fish and wildlife. Alterations to the watershed, such

as building homes and other structures and clearing

away trees and shrubs, are the leading causes for

stormwater pollution. Federal agencies identified

habitat loss from stormwater runoff as one of the

primary obstacles to salmon recovery.

STORM WATER DRAINAGE SYSTEM

STORM DRAIN

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A storm drain is defined as that portion of the storm

drainage system that receives runoff from inlets and

conveys the runoff to some point where it is then

discharged into a channel, water body, or piped system. It consists of one or more pipes connecting one or more

inlets. A storm drain may be a closed-conduit, open-

conduit, or some combination of the two.

The terminology "storm sewer" which has been in general use for many years, is gradually being replaced with the

term "storm drain" to differentiate between sanitary

sewers and storm drains.

designed to drain excess rain and ground water

from paved streets, parking lots, sidewalks, and

roofs. Storm drains vary in design from small

residential dry wells to large municipal systems. They

are fed by street gutters on most motorways,

freeways and other busy roads, as well as towns in

areas which experience heavy rainfall, flooding and

coastal towns which experience regular storms.

Many storm drainage systems are designed to drain

the storm water, untreated, into rivers or streams.

STORM DRAIN

FUNCTIONS OF STORMWATER

DRAINAGE

Remove rainwater from all exposed

portions.

Discharge to an approved point of

disposal.

Storm water drainage includes:

Roof drains

Gutters

Building storm drains

Road drains

Catch basins

Storm water pipes

What happened if rain water not properly collected

and disposed?

Nuisance and health hazard

How to discharge the

storm water?

In the past, many cities situated near large lakes,

rivers, or the ocean, used a combined sewer system

to convey both storm water and sewage.

This is no longer permitted by code.

Exceptions can be made in hardship cases with

prior approval from local authority.

With this approval, new construction can discharge

into a dual storm water and sewage system.

Otherwise, the code now requires separate sewage

and storm water collection systems.

Professional engineers usually size the storm water

drainage pipes and determine the method of

disposal.

Sample of storm water drainage

storm water

drainage

STORM WATER MANAGEMENT

URBAN STORM WATER

MANAGEMENT

Nowadays, flash flood occurs in the cities

and towns.

This is caused by the sprawl urban

development in these particular areas.

As these urban areas have emerged, it

creates more impervious areas such as in

Kuala Lumpur, Pulau Pinang and Johor

Bharu in Malaysia.

FLASH FLOOD IN KUALA LUMPUR

In addition, the amount of impermeable

areas will increase for many purposes of

land use. The transitions from forest and

open spaces areas to the commercial

and industrial areas have caused

significant changes directly to the local

ecosystem.

In other words, the natural processes i.e.

the physical, biological, chemical

processes have been disturbed due to

the unplanned development. In

hydrological perspectives, the important

physical processes in hydrological cycle

have been disrupted by this kind of

development.

The surface runoff may change its flow

path significantly due to the land

characteristics are always changed.

The increased of impervious areas do not

allow infiltration process to the ground.

Development also cut trees and

vegetation where the transpiration

process will be eliminated. It will cut the

natural vegetation.

This will result the rise of surface runoff volume and create flooding problem. The drainage system is very important infrastructures to cater the flow of runoff from catchment areas. However, drainage failure will lead to surcharged and flooding problem as well. Most of drainage facilities and silt trap did not maintain very well. It may create significant problem such as blockage, pipe leakage etc. It also increases the volume of sediment in the system.

THE IMPORTANCE OF URBAN

STORM WATER MANAGEMENT

Storm water management has a little

interest compared to wastewater and

water resources management due to less

pollution in a longer period.

*Traditionally, most of the countries had

applied the conventional drainage

system where all the surface runoff must

be discharged directly to the nearest river

or stream.

The practice of urban drainage has been

traced back to some of the earliest

recorded histories of mankind.

This practice of conveyance of

stormwater from urban areas to safer

places will involve engineering solutions

for the reduction of flood damage

potential and water pollution.

The open drain and culvert are

commonly used over the years in

Malaysia to cater the flow directly to the

river. However, as the urbanization raise

rapidly, the channels capacity insufficient

to cater to high volume of runoff before

the flows entering to the receiving

watercourse.

The policies of stormwater management have been introduced to limit the runoff characteristics after development to those that existed prior development. It is required to merge the storage and treatment facilities in the drainage system network to control the runoff from new development area before the water is allowed to enter the nearest river or stream.

CAUSES OF STORM WATER

POLLUTION 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 also contribute substantial amounts of contaminants to runoff.

Improper sewer connections lead to unseen storm water pollution.

Sometime sewer overflows, septic tank leakage also causes pollution.

EFFECTS OF STORM WATER

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

STORM WATER TREATMENT 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 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. 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

Green infrastructure replicates the natural functions of a landscape by integrating functions like storage, detention, infiltration, evaporation, and transpiration, or uptake by plants.

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.

LOW IMPACT DEVELOPMENT

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.

FACTORS AFFECTING STORM

WATER TREATMENT

BENEFITS OF STORM WATER

MANAGMENT

Minimizing or avoiding the creation of polluted storm water.

Reducing environmental impacts on the lakes, rivers and watersheds

Achieving greater harmony with the water cycle in the watershed

Potentially reducing municipal water supply requirement by using storm water as an alternative water sources.

Minimizing health risks.

THANK YOU