Design of Storm Sewer System for the Bistekville 1 of Brgy. Payatas Quezon City

March/2012

Previous Degrees

Mapua Institute of Technology

Manila City

In Partial Fulfillment of the Requirements

For the Degree of Bachelor of Science in Civil Engineering

(Degree Program)

Submitted to the School of Civil, Environmental and Geological

Engineering (SCEGE)

DELOS SANTOS, ZAIRON Z.

PAULINO, MIKHAIL DIMITRI M.

PEL, FINA KAMILLE A.

Project by

DESIGN OF STORM SEWER SYSTEM FOR THE BISTEKVILLE 1 OF

BRGY. PAYATAS QUEZON CITY

Table of Contents

Chapter 1. Introduction

………..…………………...……………………………………………..1

Chapter 2. Presenting the Challenges

………………………...…………………………………..2

2.1 Problem Statement

………………………………………………………...………….2

2.2 Project Objective

………………………...…………………………………………....2

2.3 Design Norms Considered

……………………………………………………………3

2.4 Major and Minor Areas of Civil Engineering

…………………………...…………....3

2.5 The Project Beneficiary

………………………………………………………………4

2.6 The Innovative Approach

………………………………………………………….....4

2.7 The Research Component

…………………………………………………................4

2.8 The Design Component

……………………………………………………………....4

2.9 Sustainable Development

……………………………………………………………..5

Chapter 3. Environmental Examination Report

…………………………………………………..6

3.1 Project Description

……………………………………………………………...…….6

3.1.1 Project Rationale

……………..……………………………………………..6

3.1.2 Project Location

………………………….…………………………………7

3.1.3 Project Information

…………………………………………………………7

3.1.4 Description of Project Phase

……………………………………………..…7

3.1.5 Pre-construction/Operational Phase

………………………………………...7

3.1.6 Construction Phase

………………………………………………………….8

3.1.7 Operational Phase

…………………………………………………………..8

3.1.8 Abandonment Phase

………………………………………………………...9

3.2 Description of Environmental Setting and Receiving Environment

………………….9

3.2.1 Physical Environment

………………………………………………………9

3.2.2 Biological Environment

…………………………………………………...10

3.2.3 Socio-cultural, Economic and Political Environment

……………………..10

3.2.4 Future Environmental Conditions without the Project

……………………11

3.3 Impact Assessment and Mitigation

………………………………………………….11

3.3.1 Summary Matrix of Predicted Environmental Issue/ Impacts and

their Level ofSignificance at Various Stages of Development

…...……………………...…11

3.2.2 Brief Discussion of Specific Significant Impacts on the Physical and

Biological Resources

………..…………………………………………..………14

3.3.3 Brief Discussion of Significant Socio-Economic Effects/Impacts of

the Project

…………………………………………………………………………...14

3.4 Environmental Management Plan

…………...………………………………………14

3.4.1 Summary Matrix of Proposed Mitigation and Enhancement

Measures Estimated Cost and Responsibilities

…………………………………………….14

3.4.2 Brief Discussion of Mitigation and Enhancement Measures

……………...17

3.4.3 Monitoring Plan

…………………………………………………………...17

3.4.4 Contingency Plan

………………………………………………………….17

3.4.5 Institutional Responsibilities and Agreements

…………………………….17

Chapter 4. The Research Component

…………………………………………………………...18

4.1 Abstract

……………………………………………………………………..……….18

4.2 Introduction

………………………………………………………………………….18

4.3 Review of Literature

………………………………………………..……………….19

4.4 Methodology

………………………………………………..……………………….33

Chapter 5. Detailed Engineering Report

……………………………………………...…………35

5.1 Drawings

………………………………………………….…………………………35

5.2 Technical Specifications

…………………………………………………………….37

5.3 Design Criteria for Storm Sewer

…………………………………………………….46

5.4. Summary of Pipe Sizes

…………………………………………………………..…48

5.5 Determination of Water Requirement of the future tenants of Bistekville 1

……..…49

Chapter 6. Project’s Schedule

…………………………………………………………………...50

Chapter 7. Budget Estimation

…………………………………………………………………...51

Chapter 8. Conclusion and Summary

………………………………………………………..….53

Chapter 9. Recommendations

…………………………………………………………………...54

Acknowledgement

References

Appendix

Tables, Codes and Provisions

Chapter 1

Introduction

Quezon City is one of the LGUs that lead in adopting green building standards. The city

is planning to build low-cost housing for their housing and resettlement program. In line

with this matter, they will need to invest in drainage works.The objective of the PFOR3 is

to provide the city government storm sewer system design for the eco village.

The design of the storm water drainage system will be economic and will be connected to

the storm sewer line by the local government. The storm water can be treated by the local

government if they want to. Nowadays, in engineering practice, the combined sewers

advise to be used as a sewer system. Managing the storm water prevents floods and may

help solve the shortage of water.

If the local government subjects the treatment of the storm water, it will help the future

tenants of Bistekville 1 from availing water from water line providers specifically

Maynilad. It will also conserve from using clean water. It has been PFOR3 privilege to

engage with Quezon City Government and have the opportunity to use our talents to

benefit others.

2.Presenting the Challenges

2.1 Problem Statement

Quezon City is one of the Local Government Units that adopts the Green Building

Standards to strictly adhere to energy efficiency, cost effectiveness and mitigate adverse

impacts on environmental degradation and the city government also plans to develop an

eco village that will house the informal settlers. In line with this matter, they will also

need to invest in drainage works. But, the city government may also face floods

especially on the low areas. For this reason, investigation has been made for the

possibilities of constructing a storm sewer system. The infrastructure would manage the

storm water and to have a potential source of water for the village.

2.2 Project Objective

The objective of the project is to come up with storm sewer system design for the eco

village. This will come with a layout plan of the system, project schedule and estimation.

It will come with a report comparing the storm water volume accumulated during the

rainy season and the water demand during also that season.

The Quezon City Government is planning to construct an eco village and its beneficiaries

are the teachers of Justice Cecilia Muñoz Palma High School and the informal settlers of

the city and to tie up with public and private agencies that will assist in housing and

financing design of the city project.

The design will be presented to the agencies to promote a sustainable storm sewer

system. It will help to call the attention of possible financing agencies to assist the

housing project of Quezon City. This will also serve as evidence to the public to show

where their taxes go.

2.3 Design Norms Considered

Economy and sustainability are the two design norms which are significant to this

project. Considering the challenge of the global warming that we are facing today and

minimizing the adverse impacts to our environment, the team focused on the

sustainability of the design of the storm sewer system. Treating the storm water may also

be considered by the city government as a project for possible source of water of the

village but the treatment facility will not be covered in this design.

The last and final design norm considered in the design of the infrastructure is economic.

Economic is the most important aspect of the design, knowing that Quezon City wants to

uplift the quality of life and help the homeless citizen of the city. It should be economic

in design and still be functional.

2.4 Major and Minor Areas of Civil Engineering

The major area of Civil Engineering in this project is Sewerage and Drainage

Engineering and the minor areas of Civil Engineering are the Water Supply Engineering

and Construction. Sewerage and Drainage Engineering is the major area because the

project will be focused on the storm sewer system of the village. Also, the principles and

methods in designing storm sewer system will be considered to be able to meet the

objectives of the project and to launch the most economic design for it.

The minor areas of Civil Engineering in this project are Construction and Water Supply

Engineering.

Construction – In this area, we will be using Construction Project Management in

creating a project schedule that will guide us in accomplishing the project.

Water Supply Engineering –Determining the water requirement of the tenants will

be used for comparing the volume of the storm water during the rainy season.

2.5 The Project Beneficiary

The beneficiaries for this project would be the future tenants of the low-cost housing (eco

village) at Barangay Payatas, Quezon City and the Quezon City Government, itself.

2.6 The Innovative Approach

Microsoft Office Excel2007 – used to present in organized manner the

measurements and data gathered by the researchers.

AutoCAD - Initially a general-purpose 2D drafting program, AutoCAD has

evolved into a family of products which provide a platform for 2D and 3D CAD.

Today, it is used by civil engineers, land developers, architects, mechanical

engineers, Interior Designers and other design professionals. Modern AutoCAD

includes a full set of basic solid modeling and 3D tools, but lacks the advanced

capabilities of solid modeling applications.

Rational Method – to determine the volume of the rain.

2.7 The Research Component

Storm water collected during the rainy season will be compared to the demand of the

water of the tenants. It is to show that the local government may treat the water to have

source of water besides Maynilad or other water distributors. This may be used,

especially, by the future tenants of the low-cost housing (eco village).

2.8 The Design Component

The design component for this project would be based from the topography of the site

where the “Bistekville” in Barangay Payatas, Quezon City will be constructed. Also, the

amount of rainfall, the area of the project, and the elevation must be considered for the

design of the pipes. The design should meet the local provisions and codes for the

construction and design of such infrastructure.

2.9 Sustainable Development

The team will include a report or computation showing that the storm water can be a

possible source of water for Bistekville 1. The team will recommend that the water may

be subjected to treatment by the local government. This will also help the residents have

lesser water bill if this happens.

Chapter 3

Environmental Examination Report

3.1 Project Description

3.1.1 Project Rationale

Flood is not a new issue here in our country. Almost every city had their flood issues.

Storms are really unpredictable and floods are controllable if the storm sewer system are

properly maintained. A storm sewer systemin urban and industrial areas is a facility to

dispose of liquid waste.

According to World Bank, “The Manila Sewerage and Sanitation Project aims to improve

environmental sanitation in the poor and densely populated areas of Metropolitan Manila

and develop an institutional strategy for the implementation of similar projects in the

future. The project provides for (a) rehabilitation of the sewer system in the central area

of Manila; (b) construction of a sewerage collection system in about 2,050 ha of low-

income and blighted areas; (c) staff training and technical assistance; and (d) water

quality monitoring. The project should make immediate improvements in the living

conditions of about 900,000 urban poor, of a total estimated 3 million population served

by the project.”[7]

Still the typhoon Ondoy, which hit the Philippines last September 2009, had destroyed

the storm sewer system that were designed for 50 year rain period. Ondoy almost sank

most of Metro Manila mostly Marikina City, which killed more or less 900 Filipinos and

destroyed millions worth of properties. Poor storm sewer systemsand garbage disposal

problems aggravated the impact of a typhoon that struck the Philippines at the weekend

and killed hundreds of people, the United Nations disaster prevention agency says as it

stressed the need for governments to make greater investments before other catastrophes

strike.

3.1.2 Project Location

Our project will be located at Barangay Payatas, Quezon City. Quezon City government

decided to build Bistekville 1, which has 328 housing units that will be built at Molave,

Area B Barangay Payatas, and Quezon City. This housing project will be built by Habitat

for Humanity.

3.1.3 Project Information

This project will focus on constructing a better storm sewer systemin one of the housing

projects in Quezon City. This Housing Project will be constructed by Habitats for

Humanity on the lot that was owned by Oviedo Family, for the teachers at Justice Cecilia

Munoz Palma High School in Payatas and for the other informal settlers who are in great

danger zones. According to Joselito Cabungcal, chief of the Quezon City Engineering

Department (QCED), collecting household and industrial discards from the storm sewer

systemsand waterways would have been much easier without the illegally-constructed

structures near the danger zones.

3.1.4 Description of Project Phase

This section illustrates the activities/environmental aspects, the impacts to the said

environment and the pollution control measures that were incorporated during the

planning of the project.

3.1.5. Pre-construction/ Operational Phase

During this phase, designing and planning for the propose storm water sewer system, the

team have gathered data for its design.

Table 1. Data Collection and Sources

Data Source Type of Information

Topography Urban Poor Affairs Office

(UPAO), Quezon City Hall

Topographic Map

Area of the Project Site Urban Poor Affairs Office


Plan

Volume of Rainfall PAGASA Survey

Proposed Master Plan Urban Poor Affairs Office


Structural and Civil Plans

3.1.6 Construction Phase

In the Construction Phase the project should have these following activities:

Mobilization of Machineries and Manpower

Site clearance

Earthworks/Excavations

Groundwater control

These works could distract the neighboring community. These impacts can produce

noise by the importation of equipments and materials, compounds that can contaminate

air during the earthworks, and possible water quality degradation.

There are possibilities that plants and tress could be destructed during the

construction. We also have to ensure the safety of the animals and plants adjacent to the

line of work. But for this project possible removal of plants and trees is possible because

the area of work requires to.

Lights and warning signs during the construction is needed to prevent accidents and

for the awareness of the workers and the by passers that there will be an underground

construction going on in the area of work and also for their safety.

3.1.7 Operational Phase

In this phase, placement of the concrete pipes, manholes, catch basin and other

components of storm sewer system will be installed. Technical specifications will be

examined and tested as a finishing requirement of the whole construction. Finishing

earthworks like backfilling will also be executed. Observation on the effectiveness of the

infrastructure will be conducted.

3.1.8 Abandonment Phase

In this phase, demobilization of existing structures within the project location, like

temporary fencing, headquarters of the construction workers,and equipment used in the

construction. Restoration of natural resources and geology, and clearing operations for

waste products were implemented.

3.2 Description of Environmental Setting and Receiving Environment

In this part, different kinds of environment that will be affected by the project are being

described.

3.2.1 Physical Environment

The site’s soil is wet and clayey. It is mixed with some waste. The soil on the area is

already being plowed. The climate during the site visit was humid. Some trees were

already down. The quality of water and its storage (if any) were not checked. The area is

a sloping ground and it is near from the sanitary facility of Quezon City. Its neighbors are

a school, Justice Cecilia Muñoz Palma High School, A church, which is located within

the area of the project. Therefore, the noise will come from these infrastructures and can

be affected by the noise that will be coming during the construction. The quality of air

can be considered as partially polluted. It is because the site is located near a sanitary

facility. There is an existing storm sewer system outside the project area and it is beside

Molave Street.

Figure 1. The Project Site Location

3.2.2 Biological Environment

The project area is located on the area of Quezon City where most of the infrastructure is

housing. Therefore, the ecosystem in the site is mostly trees and plants. There are no

animals living in the site except for the dog in the church that is residing in the site.

3.2.3Socio-cultural, Economic and Political Environment

The site is within the area of one of the most progressive cities ofManila. The site is a

future location of a housing and resettlement program of Quezon City. The area is owned

by the City government. The area will be developed into a housing facility in partnership

with Habitat for Humanity. The church is the only existing building in the area. The

nearby community is composed of families living in Brgy. Payatas. Justice Cecilia

Muñoz Palma High School is also in the neighborhood. Brgy. Payatas where the area

belongs can be considered a rural area of Quezon City. The means of transportation in the

area is by tricycle. The street adjacent to the site is not yet developed though there is an

existing storm sewer system and water pipe lines underlying it.

3.2.4 Future Environmental Conditions without the Project

Without having the project, the future residents of the site may have a hard time dealing

with the wastewater on their area. Possible flood will occur. Especially those residents

that were located in the lower area of the site, they will be the most affected because the

water will be stagnant on the lower area. Also, a possible reduction on their water bill

won’t be achieved.

3.3 Impact Assessment & Mitigation

3.3.1 Summary Matrix of Predicted Environmental Issues/Impacts and their Level

of Significance at Various Stages of Development

Table 2. Summary Matrix of Predicted Environmental Issues/Impacts and their Level of

Significance at Various Stages of Development

PREDICTED IMPACT ENVIRONMENTAL

COMPONENT

LIKELY TO BE

AFFECTED

SIGNIFICANCE

OF IMPACTS

MITIGATION/

ENHANCEMENT

MEASURES D/I L/S R/I

DUST GENERATED

FROM SITE

PREPARATION

AIR D S R REGULAR WATERING

OF EXPOSED

GROUND

PEOPLE D S R PROVIDE MASK TO

WORKERS AND

PERSONNEL

REMOVAL OF SOIL DUE

TO SITE PREPARATION

LAND D S R REPLANTING OF

TREES AND PLANTS,

PROPER ALIGNMENT

OF DRAINAGE PIPES

INCREASE RUNOFF DUE WATER D S R SEEDLING PLANTING

TO CUTTING OF TREES

AND REMOVAL OF

SHRUBS

THAT CORRESPONDS

TO THE NUMBER OF

CUT TREES AS

REPLACEMENT;

PROPER

CONNECTION OF

STORM DRAINAGE

LINE

SEDIMENTATION OF

DRAINAGE LINES FROM

UNCONFINED SOIL

WATER D S R INSTALL

TEMPORARY SILT

PONDS TO PREVENT

SEDIMENTATION

POLLUTION OF NEARBY

WATER BODY

WATER D S R PROVIDE SUFFICIENT

NUMBER OF

TEMPORARY

TOILETS AND

BATHROOMS THAT

WOULD BE

MAINTAINED

REGULARLY

DESIGNATE

TEMPORARY WASTE

DISPOSAL AREA;

SEGREGATION

SHOULD BE DONE

AND DISPOSED

REGULARLY

ACCIDENT PRONE AREA PEOPLE D S I PROVIDE SAFETY

EQUIPMENTS

SECURE FIRST AID

KIT

PROVIDE A STANDBY

FIRE

EXTINGUISHERS.

EMPLOY MEDICAL

PERSONNEL INCASE

OF ACCIDENTS.

IMPLEMENT SAFETY

RULES AND

REGULATIONS

DURING THE

CONSTRUCTION.

NOISE POLLUTION PEOPLE D S R AVOID

CONSTRUCTION

ACTIVITIES THAT

REQUIRE HEAVY

EQUIPMENT BEYOND

REGULAR WORKING

HOURS

MAINTAIN MOTOR

ENGINE AND OTHE

EQUIPMENTS IN

GOOD CONDITION.

TRAFFIC PEOPLE D S R INSTALL EARLY

WARNING DEVICES

AT APPROPRIATE

PLACES

DELIVERY OF

EQUIPMENTS/MATER

IALS MUST BE

SCHEDULED

GENERATION OF SOLID

WASTES

LAND D S R DESIGNATE

TEMPORARY WASTE

DISPOSAL AREA

WATER DISPOSED PROPERLY

AND REGULARLY

ECONOMIC GROWTH PEOPLE D L I IMPLEMENT

STRICTLY THE RULES

AND AGREEMENTS

OF CONTRACT

EMPLOYMENT PEOPLE D S R PROVIDE

SEMINAR/TRAINING

FOR SMALL

BUSINESS

MANAGEMENT

PRIORITIZING TO

HIRE QUALIFIED

LOCAL RESIDENTS

VIBRATION PEOPLE D S R PROVIDE VIBRATION

CONTROL MEASURES

OFFENSIVE ODORS PEOPLE D S R ACTIVITIES

ENGAGING TO THIS

IMPACT MAY BE

DONE IN AN AIR

TIGHT CONDITION

INCREASE INCIDENT OF

ACCIDENTS

PEOPLE D S R EMPLOY MEDICAL

PERSONNEL AND

PROVIDE FIRST AID

KIT

3.3.2. Brief Discussion of Specific Significant Impacts on the Physical and Biological

Resources

The project will affect the soil quality and the groundwater deposits since the project will

be laid underground. This may affect the quality of water if ever there are existing wells.

Air pollution may also be experienced because of the emission from the vehicles or

equipments within the area of construction. Dust will be generated during the site

clearance and excavation that may contribute to polluting the air within the area. Noise

from the large equipments will produce destruction that could affect the adjacent

neighborhood of the site area. Possible complaints will be expected.

In line with excavation and site clearance, cutting trees and removal of plants in the area

will be needed in order to eliminate any obstruction on the construction of project. It may

make the birds homeless when this phase of construction is reached.

3.3.3 Brief Discussion of Significant Socio-economic Effects/Impacts of the Project

During the construction this may affect the socio-economic environment especially the

community that resides nearby the project site. The noise that will be produced during the

implementation of the project may affect the students, faculties and other employees from

of Justice Cecilia Muñoz Palma and their families. The operation of the church beside the

area could also be affected, but still can be negotiated.

3.4 Environmental Management Plan

This section describes the environmental impact management and monitoring plans of

this project which are presented in detail shown in the following subsections.

3.4.1 Summary Matrix of Proposed Mitigation & Enhancement Measures Estimated

Cost and Responsibilities

Table 3. Summary Matrix of Proposed Mitigation & Enhancement Measures Estimated

Cost and Responsibilities

Project/Activity Phase Potential Environmental

Impacts

Mitigating and

Enhancement Measures

a.) Construction Nuisance or hazard to adjacent

and nearby properties

*provide temporary

perimeter fence for the

site

Increase in dust generation

due to clearing, earthwork and

civil works such as concreting

*Regular watering of

exposed soil

Cutting of affected trees

within the area of building

construction

*Planting of equivalent

number of seedling as

replacement for the cut

trees

Removal of unsuitable soil as

requirement of building

construction

*Stockpile the unsuitable

soil and spoils in flat areas

quite far from drainage

lines and use it for non-

structural application

areas

Incidence of sanitation related

illness

*Require the contractor to

provide their personnel

and workers appropriate

and sufficient portable

toilets with bath area

Incidence to accident *require the contractor to

implement safety rules

and regulations

*Implement protocol for

emergency preparedness

and response

Traffic * Alternative routes will

be implemented and

scheduled delivery of

construction materials and

equipment

b.) Operation Hazards to people and land

caused by solid waste

*Training of personnel for

emergency preparedness

generation and response

*Designate area for solid

waste segregation and

storage especially for

bulky waste

* Provide bins and bags

for small solid (office and

domestic) wastes

Hazard to people due to

vibration by

machine/equipment operation

*Provide vibration control

measures

Hazard to people due to noise

generation

* Construction will be

done during work hours

*Use equipment that will

not produce such noise,

except if needed

c.) Abandonment Sedimentation/siltation of

drainage or waterways from

unconfined stockpiles of soil

and spoils

*Install temporary silt trap

or detention ponds to

prevent siltation

Increase in air pollution due to

dust and scrap generation due to

demolition works

*Implement regular watering

and provide safety nets to

suppress dusts.

3.4.2 Brief Discussion of Mitigation & Enhancement Measures

The mitigation of our thesis will be based from the potential environmental

impacts that will be affected during construction. Each potential environment will have

an equivalent mitigation to avoid or minimize such impacts.

3.4.3Monitoring Plan

Construction of drainage in Bistekville will have a major impact on environment because

trees will be removed therefore if heavy rain will fall during construction, the site might

be flooded which may cause some delay to the project construction. Air pollution caused

by dust would be a short term impact and this is given a proper mitigation shown at Table

4.

3.4.4 Contingency Plan

If storm water sewer system would be clogged, there would be a passageway

where a person could enter and clean the storm sewer to let the storm water flow freely.

This passage way is commonly called as manhole.

3.4.5 Institutional Responsibilities & Agreements

Quezon City Government will provide the necessary plans needed for constructing the

storm sewer system of “Bistekville.” PhilippineAtmospheric, Geophysical and

Astronomical Services Administration (PAGASA) will be the source of the amount of

rainfall for the site, Brgy. Payatas, Q.C, which will be used for the design of the

catchment. Also, the Department of Public Works and Highways (DPWH) will be the

one who will monitor the project to make sure that the structure is following all the

specifications needed. For the safety of the natural resources that may be affected by the

project, Department of Environment and Natural Resources (DENR) will be the one who

will supervise it.

Chapter 4

The Research Component

4.1 Abstract

The primary purpose of this research is to provide a storm sewer system for the new

Housing project in Barangay Payatas, Quezon City called the Bistekville. The study

focuses on designing an economicstorm sewer system that would be an effective

catchment for storm water. Since the site doesn’t have an existing storm sewer system,

the project team will research on how to construct a storm sewer system that can

withstand even a strong storm will come. The design of the storm sewer system will be

dependent on the data that will be gathered from certain government sectors like

PAGASA, DPWH and Quezon City’s Engineering Office. We recommend water

treatment of the storm water that will be collected but the design won’t be on our scope.

The treatment of the storm water will be helpful for those tenants that will live there in

the future.

4.2 Introduction

Storm water volume is very unpredictable. Nowadays, managing it seems very difficult to

deal with. When it is not properly managed and controlled, it can cause damages to our

environment and may result life threatening situation. An example of this is when

typhoon Ondoy turned many areas of Manila into lakes and destroyed the design of the

storm sewer systems in those areas. Its rainwater volume is equivalent to an average of a

one month rainfall. Therefore, the resettlement and housing program of Quezon City will

need to invest for an infrastructure like storm sewer system. Since storm water is

classified as waste water, it can possibly be treated.

This project intends to have an adequate design of storm sewer to prevent the village,

Bistekville, from being flooded.

The storm sewer system will be designed economically and will be connected to a

reservoir. It is to manage the storm water within the vicinity. The design considerations

will be from the Quezon City’s Green Building Codes and DPWH. It is to comply on

their ordinances and to prevent from contributing wastes on the environment.

The main objective of the project is to come up with a design of storm sewer of

Bistekville I. This projectattempts to satisfy the following objectives.

To design storm sewer that will provide good service to the residents of the

village

To determine the amount of water that can be a possible secondary source of

water

To come up with economic designs that will sustainable development

To provide a design that will mitigate wastes on the environment

Design considerations will focus only in the quantity of rainfall that will depend on

the design period, ground elevation, slopes, location of pipes and manholes and materials

to be used. Technical specifications will also be considered and included in the study. It

will also include the cost, safety, constructability and sustainability of the project design.

4.3 Review of Literature

“Storm Sewer is a sewer designed to carry storm water and ground water infiltration, but

excluding domestic sewage and industrial wastewater. It is also call storm drain.

Storm water is an environmental process. It accumulates on the atmosphere and falls

down. Soil and vegetation absorbs infiltrates and use it. But high amount of it may result

to floods and damage the environment.

Developments in land have also negative income to the environment. It affects the

infiltration in the soil, declines the ground water. As rain falls on pavements, it flushes

the accumulated pollutants into the bodies of water and destroys habitats.

Managing it has become one of the objectives and fields of Civil Engineering. These

fields are Environmental Engineering, Water Resources Engineering and Sanitary

Engineering.

Before beginning designing storm sewer system, certain essential date must be

acquired. These are summarized in general:

Project meeting

Topographic map

Site reconnaissance

Local Land Development Ordinances

Related Engineering Designs or reports.[1]”

Location

Figure 2. This is the Location Map of Bistekville 1 from the Quezon City Planning

and Development Office

Bistekville 1 is a housing project that will help the teachers of the Justice Cecilia

Munoz-Palma High School have their own house. The village will be located beside the

said school and La Mesa Dam Reservoir is also near from the location of the village.

Figure 3. Topographic Survey of the Location of the Bistekville 1 from the Quezon

City Planning and Development Office

Design Formulas

Rational Method

Also you will need to determine the rainfall in the site that needs the infrastructure.

Rainfall information can be secured from PAGASA (Philippine Atmospheric

Geophysical and Astronomical Services and Administration).

In the absence of rainfall data, engineers have used empirical formulas for arriving at

runoff or have observed the capacity of existing natural watercourses serving an area to

be sewered and made the sewers of similar capacity. These methods are little used at

present as sufficient information can generally be found to permit an analysis of the

various factors affecting the amount of runoff and allow estimation or determination of

each separately. This is known as the rational method, and it is expressed as the

equationapplying the rational method, Eq.(1). [1]

Eq. (1)

Where: Q = Peak rate of runoff

c = Runoff coefficient

i = Average intensity of rainfall for the time of concentration

A = Drainage area in acres

We can determine the area of the drainage for our design. The runoff coefficient of an

area, however, is not fixed for all conditions but tends to become larger as rainfall

continues. This, of course, is due to the filling of depressions is impervious surfaces and

soaking of the upper layers of exposed soil. For these reason, adjustments of the

coefficient have been suggested by a number of investigators.

Chezy Formula

Water moves downstream in a pipe or channel impelled by the force of gravity. It will

move at such a velocity that the available head or fall will be used up in overcoming

friction and, in small part, to attain kinetic energy or velocity head. The amount of

friction or resistance that must be overcome will depend directly upon the roughness of

the surface of the pipe or channel, directly as the area of the contact surface,

approximately as the square of the velocity, directly as the density of the liquid. The

contact surface will be the wetted perimeter of the conduit multiplied by its length. These

relationships can be expressed as a formula

√ Eq. (2)

which is known as the Chezy formula.

where:

V= mean velocity

R = hydraulic radius, A/P

s = slope of hydraulic grade line

c = coefficient

Manning’s Formula

The Manning’s formula is much used for open-channel flow.

(

) ( )

( )

Eq. (3)

where:

C = 1 for SI units (1.486 for IP units)

V = velocity in meters per second (feet per second)

n = coefficient of pipe roughness

R = hydraulic radius in meters (feet), and

S = slope of energy line in meters per meter (feet per foot)

Roughness Coefficient

Values of n are to be used in the formula range from 0.013 to 0.015. The lowest n

values apply to new or relatively new pipe (in sections greater than 1.5 m (5 feet)) with

smooth interior surfaces, smooth bore, even joints, in excellent to good condition and

well constructed. Higher n values are required for older pipe with rough interior surfaces,

open or protruding joints, in fair to bad condition and poorly constructed. Values up to

0.017 are often justified for very old pipe (such as brick or block sewers) in extreme

deterioration, or pipe very poorly constructed with improper alignment, sags and bellies,

cracked or offset joints, broken wall sections or internal corrosion. Some manufacturers

of plastic and asbestos cement pipe report n values of 0.009 to 0.011. However, due to

uncertainties in design and construction, plus a desire to provide a margin of safety, n

values smaller than 0.013 will not normally be permitted. Variation of n with depth of

flow has been shown experimentally, and may be considered in designing sewers to flow

partially full. A solution to the Manning formula for full pipe flow is shown in figure.

Figure 4. Manning’s Formula for Full pipe

Assuming uniform flow, the value of S in the Manning formula is equivalent to

the sewer invert slope. Pipe slopes must be sufficient to provide the required minimum

velocities and depths of cover on the pipe. Although it is desirable to install large trunk

and interceptor sewers on flat slopes to reduce excavation and construction costs, the

resulting low velocities may deposit objectionable solids in the pipe creating a build up of

hydrogen sulfide, and thus will be avoided. (Guyer 2010)

The other design considerations are:

Determination of slope for laying of drainage pipes.

Determination of detention pit size.

Determination of manhole size.

Determination of retention drainage basin size.

Determination of drainage capacity of soil

The written considerations above should also comply to the DPWH and Quezon

City’s Standards.

“2.7 Thus, the project will deliver sustainable water and sanitation services through

two types of interventions. For sewerage, sanitation and drainage, project investments are

being developed collaboratively with households, communities and city councils, so that

the technical staff can respond to community needs fully. For water supply, investments

through a technical assistance loan will assist MWSS develop a Public Performance

Audit system that provides reliable and timely feedback from service consumers on the

level of satisfaction with the service.”

“4.4 Investments in drainage and sanitation will benefit a much larger proportion of

low-income residents because they address the problems of low-lying areas and squatter

settlements. As a result, morbidity caused by gastro-intestinal disease, and medical

expenses and working days lost because of illness will decline substantially.”

“As economies develop and population increases, demand for water byindustry,

commercial, agriculture, and domestic sectors necessarily expand. Globally, the supply of

water may not be limited, for instance, made the projection that for 2025, only 10

percentof total renewable water shall have been withdrawn.”

The following statements and considerations above prove the importance of the

drainage system.

Journals

Urban Stormwater Drainage Management: The Development of a multicriteria

decision aid approach for best Management Practices

Stormwater management in urban or suburban areas is becoming increasingly

oriented to the use of best management practices for countering of urban growth.

Many different BMP’s and several district criteria (technical, hydraulic,

environmental, social, economic, maintenance criteria) need to be considered in

the decision-making process. Moreover, the preferences of stakeholders can vary

according to the different management strategies and vested interests. [10]

Drainage and Stormwater Management Strategies for Low-income Urban

Communities

Urban conditions exacerbate drainage problems; runoff is increase by

impermeable urban surfaces and, due to inadequate development control

mechanisms and their incompetent enforcement, settlements are constructed with

little consideration for stormwater drainage. The poor are disproportionately

affected; they often reside in informal settlements located on marginal land – low-

lying land, riverbanks, floodplains and steep hillsides – that the formal housing

market does not want or need. Although these sites are vulnerable to the impacts

of flooding, the benefits of living nearer sources of employment and urban

services generally outweigh the disadvantages associated with flooding, which are

generally perceived as a natural and seasonal event. [11]

Typology of Flood types, Characteristics and Impacts

Flood

type

Characteristics of Flooding and Impacts

Type A Localized flooding caused by inadequate drainage of stormwater

runoff, which can happen virtually every time it rains where the

provision of drainage infrastructure is very poor. The main impacts

of these events are related to a deterioration in environmental health

conditions – notably those related to water-related diseases.

Type B Flood events of this type occur less frequently that type A floods, but

affect larger areas. The impacts may include temporary disruption to

transportation systems and inconveniences to city life. These events

contribute to the propagation of water-related diseases and can cause

structural damage, but not as severe as those related to Type C

events.

Type C Large-scale inundation causing widespread disruption and damage

affecting communities and businesses throughout cities. These events

are infrequent and often reach the headlines due to the dramatic scale

of the impacts and structural damage.

Figure 5.Stagnant water and disease transmission – the health consequences

of poor drainage

Water Quality Characteristics of Storm Sewer Discharges and Combined Sewer

Overflows

“Until the past decade or so, only the quantitative aspects of storm water

discharges were the primary concern of design engineers, though mention of the

quality aspects of storm runoffs appeared sporadically in the technical literature of

the 1940s and 1950s. Recognizing urban storm runoff as a significant source of

pollution, the U. S. Public Health Service authorized several demonstration

projects. Results of studies performed by consulting engineers, municipal

agencies, university research teams, and state organizations have been reported as

part of the Water Pollution Control Series published by the Water duality Office

of the Federal Environmental Protection Agency. These and other sources cited in

this review are listed at the end of this publication. Also, a list of additional

references has been included to permit examination of related research activities if

desired.”

“The quality and quantity of storm runoff will depend on several factors.

Intensity, duration, and areal extent of storms, and the time intervals between

successive storms have significant effects both on the quantity and quality of

runoff. Land contours, land uses, population densities, incidence and nature of

industries, size and layout of sewer systems, and other factors also have their

influence. Studies on storm water qualities differ widely in pattern and

background conditions. Therefore observations for combined sewer or separate

storm sewer overflow characteristics cannot be consolidated as representative

conditions throughout the United States.” [12]

Road and Urban Storm Water Drainage Network Integration in Addis Ababa: Addis Ketema Sub-City

“Urbanization along with its impermeable structures is the major causes of

flooding in urban areas. Urban storm water influences the service life of urban

infrastructures. The rainfall intensity and characteristics of catchment area are the

major factors for designing urban storm water drainage facilities. These facilities

have a paramount advantage to safely dispose the generated floods to ultimate

receiving system. This study has assessed the integration of road and urban storm

water drainage infrastructure with the help of topographic map and also the

condition, pavement type and hierarchy of every road and drain were assessed in

Addis Ketema Sub-city. This study area, particularly, is bounded in between

Addis Ababa Municipality (East), Addis ‘Ketema’ high school and General bus

terminal (West), ‘Yohannes’ Church (North-East) and Bethel high school (North-

west). The objectives of this study includes: to identify sites most prone to

flooding problems, to assess the existing condition of road and urban storm water

drainage infrastructure, to identify the extent of integration of urban storm water

drainage infrastructure in road projects provision, to examine the impacts of

Urban storm water drainage infrastructure integration on road performance and

related environment issues and to make recommendations on road and Urban

storm water drainage infrastructure integration and their provision and

management. An exploratory and descriptive type of methods were used to

describe and investigate the existing condition and coverage and level of

integration between road and Urban storm water drainage infrastructure

infrastructures respectively. Data collection methods were carried out using both

primary and secondary data sources, but the secondary data source was only

relevant to reinforce the primary data, which was accomplished with the help of

topographic map and a check list. The collected data were analyzed and presented

using Microsoft-excel, AutoCAD and ArcGIS and tables, graphs and percentages

respectively. The findings of this study includes: the major causes of flooding

which was found to be the blockage of urban storm water drainage lines along

with inadequate/poor integration between road and urban storm water drainage

infrastructures. This study strongly recommends improvement in the integration

of road and urban storm water drainage infrastructure and integrated solid waste

management to prevent over flowing of flood as a result of blockage of

drains.”[13]

Stormwater treatment

“Stormwater can be polluted. When collected in a combined sewerage system it is treated

with the wastewater, though treatment is not effective during peak heavy stormwater run-

off periods resulting in combined sewer overflow (CSO) that is not treated. Storage

basins or tanks can be used to accommodate moderate peak flows of combined

stormwater and wastewater, and treating the stored water at night when wastewater flow

is a minimum.”[9]

Figure 6.Stormwater treatment by settling

“Separately collected stormwater is generally treated by passing it through a settling

basin to remove solids (Figure 7). The retention time in the settling basin is designed so

that solids can settle in say 20 minutes for a one in five year storm-event. For storm-

events less than the design value, removal efficiency is greater, while for storm-events

greater than the design value removal efficiency is lower. Mechanical devices have been

developed that can trap gross solids. Both settling basins and mechanical traps need to be

cleaned regularly to maintain solids removal efficiency.

Naturally landscaped stormwater drains can help filter out fine sediments through the

action of vegetation slowing down the flow and trapping solids. Permeable surfaces allow

rainwater to percolate into the soil, thus treating the water in much the same manner as

Figure 7. Management train for stormwater at the local sub-catchment and catchment levels

land based treatment of wastewater and at the same time reduce the amount of run-off.

Pavements have been designed and manufactured for this purpose. Directing run-off to

vegetated area (rainwater harvesting) can reduce down-stream flow and reuse the water

for maintaining plant growth. This is especially beneficial in arid climates. Four

techniques for stormwater treatment are described below. Used judiciously these can treat

stormwater locally (Figure 7). Applying these on a sub-catchment scale (site), or whole

catchment scale (region) can reduce flooding and the undesirable impacts of stormwater,

while at the same time improve the amenity value of the landscape through creation of,

for example, passive recreation water bodies.

1. Filter strips and swales

Filter strips and swales are vegetated surface features that drain water evenly off

impermeable areas (Figure 8). Swales are long shallow channels, while filter strips are

gently sloping areas of ground. They allow run-off to flow in sheets through vegetation,

slowing and filtering the flow. Swales also act to temporarily store and infiltrate the run-

off into the ground. Sediments are removed from the water, and vegetation can take up

any nutrients in the water. Swales and filter strips can be integrated into the surrounding

land use, for example, road verges. Local grasses and flower species can be introduced

for visual effect and to provide a wildlife habitat. Maintenance consists of regular

mowing, clearing litter and periodic removal of excess silt.

2. Filter drains and permeable surfaces

Filter drains consist of permeable materials located below ground to store run-off. Run-

off flows to the storage area via a permeable surface (Figure 9). The permeable surface

can be in the form of grassed or graveled areas, paving blocks with gaps between

individual units or paving blocks with vertical voids built in. Water is therefore collected

from a large surface area, stored in the filter drains and allowed to infiltrate through the

soil. The permeable fill traps sediments and thereby cleans the run-off. Filter drains and

permeable surfaces are currently used for road verges and car parks. The surfaces should

be kept clear of silt and cleaned regularly to keep the voids clear. Weed control may be

necessary.

Figure 8. Filter strip and swale in an urban landscape

Figure 9. Permeable pavements

3. Infiltration devices

Infiltration devices drain water directly into the ground. They include soakways and

infiltration trenches, which are located below ground, and into which stormwater run-off

is directed. They function by storing water and allowing the water to infiltrate into the

ground. Figure 10 shows a cross-section through a traditional soakway or a chamber

soakway. They work well when the soil is permeable and the groundwater table is not

close to the surface. Maintenance consists of regular inspection to ensure the infiltration

capacity is maintained. Areas draining to an infiltration device should be kept clear of

silt, as this will get washed into the device and reduce its permeability as well as filling

up space that should be used for storage.

Figure 10. Cross section through a traditional soakway or a chamber soakway (CIRIA, 1999)

4. Basins and ponds

Basins are areas for storage of run-off that are dry during dry weather, whereas ponds

have permanent water (Figure 11). Both store water and therefore attenuate the flow of

water during a storm. Flow downstream of the basins or ponds can therefore be

controlled. Basins and ponds also act as infiltration devices. Basins and ponds are usually

used at the end of a train of treatment for stormwater, and provide additional step if

source control does not have an adequate capacity to control run-off. Detention time is of

the order of two to three weeks. Both basins and ponds can be vegetated, so that we can

have a range of features, including wetlands that have amenity values for passive

recreation or wildlife habitat. Run-off water quality is improved upon storage in basins or

ponds because of sedimentation of solids, bacterial action and nutrient uptake by

vegetation. Water stored in ponds can also be used for irrigation of parks and gardens or

for fire-fighting and other purposes. Basins and ponds need to be maintained to control

vegetation and removal of accumulated silt.”[9]

Figure 11. Pond, basin and constructed wetland for stormwater treatment

4.4 Methodology

The team had to come up with studies and researches about the right and effective

design for the storm sewer system. A project proposal is needed to be done and be

approved to start the planning of the project. The proposal should contain the main

purpose of the project and the benefits that it will bring to the people of the area location,

which on the project is the local government of Quezon City. The researchers are also the

participants of proposed project. When the proposal is approved, the team has to review

some related literatures to know how storm sewer system is built and what data should be

gathered to start the project. For the data gathering, the team will have the site observed

to check if there will be some existing structures on the site location. We gathered data

from Quezon City Hall, NAMRIA, and PAGASA. In Quezon City Hall, we have not

gathered that much data and they did not entertain our needs for the reason that the data

that we needed is quite confidential, i.e. they had given us only the Power point

presentation of the plan of Bistekville, not the accurate plan. Therefore we traced and

scaled the given plan in order to come up with our design using AUTOCAD. We got the

Rainfall Intensity from PAGASA Science Garden and the Topographic Map of the

location of Bistekville. Topography is also applied. If the data are already gathered, we

can start the designing of the project and identify components for a sustainable

development. Construction of the system comes after the detailed planning. The software

that can be aids for the design of the project is AUTOCAD (for measurements) and

Microsoft Excel (for computations).

Design parameters are set so that the study should only be limited. These parameters

include deciding the layout and component location and orientation of the proposed

project, taking responsibility for using appropriate design tools, and ensuring

comprehensive documentation of the progress of the project.

Proper design of the storm sewer system should require the accumulation of certain

basic data; familiarity with the project site and basic understanding of the hydraulic and

hydrologic principles and drainage policy associated with the project design.

These data should include the general layout of the proposed site, pertinent physical

features of the land, surface features (such as topographic map).

After the proposed project have been designed and evaluated, the project should

include existing physical features of the project area. The design of the project should

follow a system flow and a project’s schedule, so that the researchers would not be lost

on track.

Design Procedure:

• Designation of manholes by numerals.

• Length of sewer.

• Gradient.

• Design flow.

• Velocities at design flows.

• Pipe diameter and roughness coefficient.

This research/design proposal attempts to prevent the future problem that may

occur with regards to the storm sewersystems of Payatas, Quezon City, particularly the

design of the existing systems. By doing so, we have determined several factors like

precipitation rates in the area and the current amount/volume of storm sewage it

produces. We came up with our own design based on the precipitation rates we have

acquired and came up with results which will be shown on the next chapters.

5. Detailed Engineering Report

5.1 Drawings

Figure 12. Site Development Plan

Figure 13. Site Layout Plan

5.2 Technical Specifications

Storm Sewer System

General

Storm sewer facilities shall be constructed in the locations and in conformance to

the lines, grades and details shown on the plans.

Related work of excavation, trench, bedding, backfill and surface restoration

requirements for the work of this section are shown on the detailed drawings of the plans

and specified elsewhere in the specifications.

Notes

1. The storm sewer system was designed where the topographic elevation is uniform

and with the downward slope from the highest elevation.

Scope

1. The work to be done under this contract shall include the furnishing of all

labor, materials, tools and equipment to construct complete in place the

sanitary sewer and all appurtenances as show on the drawings, plans and as

specified herein.

2. The Contractor shall excavate all materials encountered, furnish and compact

foundations where required, furnish and install all timbering, sheeting and

bracing necessary to safely support the work, remove any ground water

encountered during excavation operations, protect, repair, relocate, maintain

and restore all sub-surface, surface and overhead structures directly disturbed,

damaged or affected by construction operations and furnish all backfill and

other appurtenant items as necessary.

3. The drainage network shall consist of both minor and major systems. The

minor system consists of underground conduits, open channels and

watercourses to handle peak flows from a five (5) year to twenty-five (10)

year return period storm. The major system consists of overland flood paths,

roadways and watercourses to handle design flows above minor system flows

up to the twenty five (25) year return period storm. In special conditions

where adequate overland flood paths cannot be established, portions of the

minor system may be enlarged to accommodate the major flows.

4. The general design and construction of storm sewers shall be in accordance

with the standards as detailed in this section.

5. City master drainage plans shall be used in the design of individual drainage

networks. Each system, minor and major, shall be considered in light of the

drainage basin(s) of which it is a part. The design of the systems shall

accommodate storm water from lands, tributary to and flowing through the

area under consideration, and minimize the negative effects of the outflow on

downstream properties and drainage facilities.

Hydrology

1. Design Return Period:

The design return period used is 25 years.

2. Catchment Area:

(a) For both the major and minor flow routings, the contributing catchment

area shall be governed by the natural contours of the land; and

accommodating the overall drainage areas.

3. Minor System - Rainfall Runoff Calculation Method:

(a) The minor system storm sewer calculations shall be based on the Rational

formula:

Q = C I A (2)

where

Q = storm runoff flow in cu.m./second

A = contributing catchment area in ha.

C = the coefficient of runoff

I = the rainfall intensity in mm/hr.

(b) Time of Concentration:

Inlet times will vary but are not to be less than five (5) minutes or

more than ten (10) minutes for overland flow into the storm sewer system.

(c) Rainfall Intensity:

The rainfall intensity shall be taken from the Rainfall Intensity –

Frequency Duration table for Science Garden (Quezon City) (Based on 41 years

of record including BagyongOndoy) shown on the table below for the applicable

design year return flow.

Table 4. Precipitation

0 10

(min)

20 30

2 (yrs) 19.1 28.7 35.6

5 28 42.1 53.3

10 33.8 51.1 65.1

20 39.4 59.6 76.3

25 41.2 62.3 79.9

50 46.6 70.7 90.9

100 52.1 79 101.8

(d) Coefficient of Runoff (C):

The choice of coefficient of runoff "C" shall be based on ground slope, type of

ground or surface cover, size of drainage area and the expected ultimate land use

of the properties within the drainage area.

Manholes

a. Manholes shall be installed at the upper end of each line, at all changes in

grade, size, or alignment, at all sewer intersections, and at a spacing of no more

than 120 m. b. The minimum diameter of the manhole will be 1.2 m and shall meet the

requirements of ASTM C-478. Larger manholes will be permitted for sharp

changes in alignment and larger diameter sewers.

c. A drop inlet shall be provided for in/out invert elevations greater than 3.5 m.

d. Manholes that are deeper than 36 inches shall have steps. Manhole steps shall

be press set plastic, or approved equal. Steps will also be provided on the

outside of raised manholes when the top elevation is greater than 0.9 m above

the existing ground elevation.

e. A bench shall be provided on each side of the flow channel when pipe size is

less than manhole diameter. The bench shall slope 1 inch per foot.

f. Manholes in off-street locations shall be a minimum of 1 foot above finish

grade. Manholes in flood plains shall extend 0.6 m above the 100 year flood

elevation or be provided with sealed covers and vented.

g. Raised manholes shall be no higher than 1.2 m above the surrounding ground.

h. When connecting to an existing manhole the existing manhole shall be core

drilled. Inlet and outlet pipes shall be connected to new and existing manholes

with a gasket flexible watertight connection.

i. All manhole covers will be perforated and marked “Storm Sewer”.

j. All manholes shall be vacuum tested during the final testing procedures.

Pipe Design Details

1. Grades and Velocity of Storm water in Pipes and Service Connections:

(a) The minimum allowable velocity 0.76 m/s.

(b) Where the pipe discharge velocity of the design flow exceeds 1.5 metres per

second, into an open ditch or water course, provision shall be made for the

installation of an energy dissipator to reduce flow velocity to the acceptable

rate.

(c) There are no maximum allowable velocities, however, where grades exceed

10%.

(d) All 100 mm diameter service connections shall have a minimum grade of two

percent (2%).

2. Pipe and Service Connection Sizes:

(a) Minimum pipe size shall be 300 mm diameter except that in residential areas

200 mm diameter may be approved by the City Engineer in the final section of

a lateral sewer providing the pipe has the required capacity and extension in

the future is precluded by physical barriers or there is existing alternate pick-

up of drainage from adjacent areas.

(b) Unless otherwise approved by the City Engineer downstream pipe diameter

shall be greater than or equal to upstream pipe diameter.

(c) Residential service connections shall be a minimum 100 mm diameter, except

that service connections serving lawn basins shall be minimum 150 mm

diameter.

(d) Commercial and Industrial service connections shall be a minimum 150 mm

diameter.

3. Pipe Friction Factors:

(a) Storm sewers shall be designed using the Manning Formula. The minimum

‘n’ value shall be 0.013 for all approved pipes.

4. Pipe and Service Connection Depths:

Unless otherwise approved or required:

(a) Minimum cover on lateral sewers shall be 1.5 meters in road right-of-ways

and 1.0 meters in untraveled areas,

(b) Minimum cover on service connections shall be 0.75 meters,

(c) Service connections shall be deep enough to accommodate by gravity the

lowest elevation of each lot serviced. In addition, all existing foundation

drains shall be accommodated. For vacant lots, service connections shall also

be deep enough to accommodate by gravity foundation drains for future

building(s) constructed to the minimum basement floor elevation as

determined by the code.

(d) Storm sewer mains shall be deep enough so that all service connections

accommodating surface and foundation drainage from all lots in the upstream

drainage basin can be drained to the storm sewer system by gravity.

5. Location of Storm Sewer Mains and Service Connections:

(a) Storm sewer mains shall be located not less than 3.0 meters horizontally and

0.45 meters vertically from all water mains.

(b) Wherever possible, storm sewers shall be located on the high side of the street

centre line where only the high side is served by the sewer and on the low side

where both sides are served by the sewer.

(c) All lots shall be provided with a storm sewer service connection.

(d) Storm sewer mains may be installed in a common trench with sanitary sewers

provided the minimum outside pipe separation is 300 mm.

Materials

1. Reinforced concrete culvert, storm drain and sewer pipe (ASTM C76).

a. The specifications apply to reinforced concrete pipe intended to be

used for the construction of storm sewers. The size, type and class of

the concrete pipe to be furnished shall be shown on the plans or

specified under the item of work for the project.

b. Materials- Except when permitted by the Engineer, no materials shall

be used in manufacturing of the pipe other than the materials

conforming ASTM C-76.

c. Reinforcing shall conform to the requirements of AASHTO M-170.

d. Joints shall conform to AASHTO M-170. When pipe joints of the

reinforce concrete collar type or of rubber gasket type are specified or

indicated on the plans, joint details shall be submitted to the Engineer

for approval.

e. Pipe may be rejected failure to meet any requirement specified in

AASHTO M-170. Imperfections, variations and non-conformance

with the plans or specifications of causes for rejection in sewer.\

2. Asbestos cement pipe for culverts and storm drains (AASHTO M 217)

a. These specifications apply to asbestos cement pipe to be used in storm

drains and related work. Unless otherwise specified, the pipe shall comply

with the requirements of AASHTO M-217. The diameter and class of the

asbestos cement pipe to be furnished shall be as specified on the plans.

Each pipe length shall be provided with a coupling designed to maintain

alignment and insure a close fitting, flexible joint. Epoxy bonded fittings

may be used only when specified. Pipe stronger than that specified may be

furnished at the Contractor’s option, and at his own expense, provided such

pipe conforms in all other respects to these specifications.

b. Materials used in the manufacture of asbestos cement pipe and fittings shall

be tested in accordance with AASHTO M-217.

c. The basis of acceptance of lots shall be load strength test, compliance with

specifications, inspection of pipe manufacture and inspection of completed

pipe.

d. Pipe may be rejected for any crack, any piece broken from the pipe or other

irregularities, deficiencies in wall thickness, and improper machining of

ends of pipe lengths.

3. Cast-In Place Concrete Pipe (AASHTO M 86)

a. Cast-in place concrete shall consist of Portland cement concrete in accordance

with these specifications.

b. Concrete for cast-in place shall be at least 6 sack mix and slump between 1 and

3 inches. Aggregates shall not be larger than one third minimum wall

thickness. Cement shall be type I or II. The cement shall be free from lumps

and damaged cement. The fine and coarse aggregates shall conform to the

requirements of these specifications. Slump shall not exceed three inches.

c. Admixtures shall meet the approval of the Engineer before use.

4. Joint Mortar – joint mortar for concrete pipes shall consist of 1 part, by volume of

Portland Cement and two (2) parts of approved sand with water as necessary to

obtain the required consistency. Mortar shall be used within 30 minutes after its

preparation.

5. Rubber Gaskets (AASHTO M 198)

6. Corrugated Metal Units – The units shall conform to Plan dimensions and the

metal to AASHTO M 36.

7. Frames, Gratings, Covers and Ladder Rungs – Metal units shall conform to the

plan dimensions and to the following specifications requirements for the

designated materials.

a. Metal gratings and covers which are to rest to frames shall bear on them

evenly. They shall be assembled before shipment and so marked the same

pieces may be reassembled readily in the same position when installed.

b. All castings shall be uniformly coated with asphalt-based emulsion meeting the

requirements of ASTM D 1187, Asphalt-base Emulsion for use as Protective

Coating for Metal.

c. The steel grate should undergo tests to determine the strength and load that it

could carry. Loading conditions of grates depend on their specific uses and

locations.

d. The steel frame clear openings of grates shall be 15 mm larger than the

nominal sizes of industry standard sized pits. These pits increase in size in

increments of 150 mm.

e. The drainage grates shall be identified by their internal clear opening

dimensions of the frame. Metal units shall conform to the approved plan

dimensions and specifications requirement for the designated materials.

f. Metal unit shall conform to ASTM A 36 / AASHTO M 183.

g. Manhole steps shall be constructed of ¾ inch diameter deformed reinforcing

steel bars, drop-step shape, 14 inches wide minimum, and shall be hot-dip zinc

coated after fabrication, in conformance with the requirements of ASTM

A123.

8. Granular Backfill Filter Material - Granular backfill filter material shall be

permeable and shall meet the requirements of AASHTO M 6, except that

soundness test will not be required ad minor variation in grading and content of

deleterious substances may be approved by the Engineer.

9. Structural concrete used shall attain a minimum 28-day compressive strength of

20.68 MPa.

10. Sewer and manhole brick (Made from clay or shale) AASHTO M 191

11. All materials shall be subjected for acceptance to condition at the latest practicable

time the Engineer has the opportunity to check for compliance prior to or during

incorporation of materials into the work.

Trench Excavation

The excavation for conduits placed in embankment fill, shall be made after the

embankment has been completed to the specified or directed height above the designed

grade of the conduit.

When so specified on the Plans, the excavation for conduits placed in embankment

fill, shall be made after the embankment has been completed to the specified or directed

height above the designed grade of the conduit.

Excavation

Excavation shall be made accurately to the lines, grades, and elevations shown or as

directed. Excavation shall be sufficient size to permit the placement and removal of forms

for the full length and width of structure.

Backfilling

Wherever a trench is excavated in the existing or proposed roadway, sidewalk or other

areas where settlement would be detrimental, the entire trench shall be backfilled with

gravel and compacted to 95% of maximum density.

Bedding

The bedding shall conform to one of the classes specified. When no bedding class

is specified, the requirements for Class C bedding shall apply.

Class A bedding shall consist of a continuous concrete cradle conforming to the

plan details.

Class B bedding shall consist of bedding the conduit to a depth of not less than 30

percent of the vertical outside diameter of the conduit. The minimum thickness of

bedding material beneath the pipe shall be 100 mm. the bedding material shall be sand or

selected sandy soil all of which passed a 9.5 mm sieve and not more than 10percent of

which passes a 0.075 mm sieve. The layer of the bedding material shall be shaped to fit

the conduit for at least 15 percent of its total height. Recesses in the trench bottom shall

be shaped to accommodate the bell when bell and spigot type is used.

Class C bedding shall consist of bedding the conduit to a depth of not less than 10

percent of its total height. The foundation surface shall be shaped to fit the conduit and

shall have recesses shaped to receive the bells, if any.

Laying Pipe

Each pipe shall be carefully examined before being laid and defective or damaged pipe

shall not be used. Pipelines shall be laid to the grades and alignment indicated. Proper

facilities shall be provided for lowering sections of pipe into trenches. Under no

circumstances shall pipe be laid in water and no pipe shall be laid when trench conditions

or weather are unsuitable for such work. Dewatering of trenches during construction shall

be provided as necessary.

Concrete pipe laying shall proceed upgrade, with the spigot ends of bell and spigot

pipe and the tongue ends of the tongue-and-groove pipe pointing in the direction of the

flow.

Circular concrete pipe with elliptical reinforcing shall be so placed that the

reference lines designating the tap of the pipes will not be more than 5 degrees from the

vertical plane through the longitudinal axis of the pipe. In all backfilling operations care

shall be taken to prevent damage to or misalignment of the pipe.

Pipe Joints

Rigid pipes may either be of bell and spigot or tongue and groove design unless

another type is specified. The method of joining pipe sections shall be such that the ends

are fully entered and the inner surfaces are reasonably flush and even.

Joints shall be made with (a) Portland Cement mortar, and (b) Rubber gaskets, or

any other type, as may be specified. Mortar joints shall be made with an excess of mortar

to form a continuous bead around the outside of the conduit and finished smooth on the

inside. Rubber ring gaskets shall be installed so as to form a flexible water-tight seal.

Pipe shall be inspected before any backfill is placed. Any pipe found to be out of

alignment, unduly settled, o damaged shall be taken up and replaced.

Structures

Manholes, catch basins, inlets, and other storm sewer structures, shall be constructed as

shown on the plans.

Cleaning

All storm sewer lines, manholes, catch basins, inlets and similar structures, shall be

thoroughly cleaned of all dirt, debris and obstructions of any kind, to the satisfaction of

the Engineer.

5.3 Design Criteria for Storm Sewer

Storm sewer system is a system of sewer that will collect storm water runoff on the

ground surface and convey it away and through the roadway right-of-way in a way that it

will sufficiently drains the area and minimizes the possibility of flooding and damage to

properties. Storm sewer system consists of curbs, gutter, inlets, manholes and storm

sewers. The hydraulic capacities and placement of storm sewer system should be

designed to consider the damage to the property.

In this design, the computation for the flow is determined first using Rational Method.

Using Manning’s Formula, the determination of velocity will be obtained, then solving

for the required diameter of the pipe.

Table 5. Tabulated Computations

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5.4 Summary of Pipe Sizes

Table 6. Summary of Pipe Sizes

1

5.5 Determination of Water Requirements of the future tenants of

Bistekville 1

The analysis of the daily requirement of the future tenants of Bistekville was used to

compare for the total storm water volume accumulated by the storm sewer. It is to justify

that it can satisfy the needs of the tenants, if the local government will treat this water.

The wet season of the Philippines was used a criteria in this analysis. It is used for the

determination of the volume of storm water during this season and the water requirement

of tenants during only this season.

Figure 14. Determination of Water Requirement of the Tenants of Bistekville 1

1

6. Project’s Schedule

Project's schedule is the estimate of schedule duration from the start of the

construction of the sewer system which will be a guide to be used so that the construction

will be done on time. For our Project schedule, it should be noted that the made schedule

is only for pipe laying.

Figure 15. Project Schedule

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7. Budget Estimation

The estimation of the project includes the general work, civil works, concreting,

pipe work, direct and indirect costs.

Table 7. Budget Estimation

1

1

8. Conclusion and Summary

Based from the calculations for the design of the storm sewer system, the pipe

diameters to be laid are 0.30, 0.36 and 0.53 mm. These sizes are capable of withstanding

the volume of rain with 41.2 mm of precipitation.

In the determination of water requirements of the future tenants of Bistekville 1, it

showed that the storm water volume for a day during the rainy season of the Philippines

with the assumed rate of precipitation which is 41.2 mm., is 3,014,887 cubic meters.

During also that season, the water requirement of the tenants of the village is 320427.9

cubic meters. Therefore, comparing the two values, it shows that the storm water is

higher than the water requirements and is capable of supplying these requirements if the

local government will subject this water to treatment. They may also adapt the methods

of treatment discussed.

Storm water is a resource and the key to the increasing demand of readily available

water. As the climate changes, we should come up with different techniques to adapt to

these changes and one of these techniques is to imply the possibility of using effluent

water (water that had been treated).

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9. Recommendations

The study focused on what must be the design of the storm sewer system if the natural

grade and the lowest elevation of the site will be considered, and the volume of the storm

water during the rainy season that can be subjected to treatment (by others). After

thorough analysis of data, the recommendations are as follows:

The study needs more sufficient data to be improved in order to meet the green

and sustainable design which is implemented in the Local Government of Quezon

City.

Cooperation of the local government with future developers will further improve

the design or may be the goal to meet to sustainable development.

The volume of the storm water collected may be subjected to treatment by the

local government. It can be a possible source of water for the Bistekville 1.

1

ACKNOWLEDGEMENT

The researchers would like to extend their heartfelt gratitude and acknowledge the help of the

following people for making this thesis a reality:

First of all, God, for the unconditional love, and guiding, enlightening and for giving us

knowledge that made us capable of accomplishing the study.

Our loving family specially our parents, for providingus with our needs, financial and

moral support and believing that we can do this;

Our adviser, Engr. Bienvenido A. Cervantes, for entertaining our inquiries and attending

to our questions;

Our research facilitator, Dr. Francis Aldrine A. Uy, for being considerate enough and

giving us more time to prepare the study and composing ourselves for the big day.

Our classmates who extend their knowledge and abilities to teach and help us to achieve

the end of this study.

Our site engineers from our OJT who entertained our concerns and questions during the

completion of the study.

Our professors who entertained our inquiries and questions during the completion of the

study.

Ms. Margie Bautista from PAGASA-Science Garden who gave us the data we need for

free.

1

References

1. Steel, Ernest W., Water Supply and Sewerage: Fourth edition, McGraw-Hill

Kogakusha, Ltd.

2. Magtibay, Bonifacio, Philippine Regulations on Sanitation and Wastewater

System, BB Magtibay’s Publishing House, Cavite, Philippines

3. Gribbin, John E., (1997). Hydraulics and Hydrology for Stormwater Management.

Delmar Publishers

4. Herminia, Francisco A. and Rola, Agnes C., (2004). Winning the Water War.

Philippine Institute of Development Studies.

5. Quezon City, (2011). QC Leads LGUs In Adopting Green Building Standards.

Available at

http://www.quezoncity.gov.ph/index.php?view=article&catid=1%3Alatest-

news&id=631%3Aqc-leads-lgus-in-adopting-green-building-

standards&format=pdf&option=com_content&Itemid=122 on September 1,

2011.

6. Russel, David L.,(2006). Practical Wastewater Treatment. John Wiley and Sons,

Inc.

7. World Bank, (1997).Philippines- Water Districts Development Project. Available

at http://www-

wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/1997/07/29/00

0009265_3971104184315/Rendered/PDF/multi_page.pdf. Staff Paper

8. World Bank, (2000). Manila Sanitation and Sewerage Project. Available

http://web.worldbank.org/external/projects/main?pagePK=64312881&piPK=6430

2848&theSitePK=40941&Projectid=P004479 on September 4,2011.

9. International Source Book on Environmentally Sound Technologies for

Wastewater and Stormwater Management (March 2002)

athttp://www.unep.or.jp/ietc/publications/freshwater/sb_summary/9.asp

10. C. Martin, Y. Ruperd, M. Legret. Urban Stormwater Drainage management: The

development of a Multicriteria decision aid approach for Best Management

Practices. European Journal of Operational Research (9 August 2006)

http://www.quezoncity.gov.ph/index.php?view=article&catid=1%3Alatest-news&id=631%3Aqc-leads-lgus-in-adopting-green-building-standards&format=pdf&option=com_content&Itemid=122



http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/1997/07/29/000009265_3971104184315/Rendered/PDF/multi_page.pdf



http://www.unep.or.jp/ietc/publications/freshwater/sb_summary/9.asp

1

11. J. Parkinson. Drainage and Stormwater Management Strategies for Low-income

Urban Communities. Environment and Urbanization 2003 15:115

12. V. Kothandaraman. Water Quality Characteristics of Storm Sewer Discharges

and Combined Sewer Overflows. Urbana 1972

13. D. Belete. Road and Urban Stormwater Drainage network Integration in Addis

Ababa: Addis Ketema Sub-city. Journal of Engineering and Technology Research

Vol 3(7), pp. 217-225, July 2011

14. United Nations Economic and Social Commission for Asia and the Pacific Case

Studies on Water and Sanitation for the Poor, “Wastewater treatment facility in

the Muntinlupa Public Market, Philippines” at

http://www.unescap.org/pdd/prs/ProjectActivities/Ongoing/Water/Muntinlupa/Waste

waterTreatmentFacilityInTheMuntinlupaPublicMktPhilippines.asp

15. Encyclopedia Britannica: Britannica Academic Edition, “Wastewater Treatment”

at http://www.britannica.com/EBchecked/topic/666611/wastewater-treatment

http://www.unescap.org/pdd/prs/ProjectActivities/Ongoing/Water/Muntinlupa/WastewaterTreatmentFacilityInTheMuntinlupaPublicMktPhilippines.asp

http://www.unescap.org/pdd/prs/ProjectActivities/Ongoing/Water/Muntinlupa/WastewaterTreatmentFacilityInTheMuntinlupaPublicMktPhilippines.asp

http://www.britannica.com/EBchecked/topic/666611/wastewater-treatment

1

LIST OF TABLES

Table 1. Data collection and sources 7

Table 2. Summary Matrix of Predicted Environmental Issues/Impacts and their Level of

Significance at Various Stages of Development

11-13

Table 3. Summary Matrix of Proposed Mitigation & Enhancement Measures Estimated

Cost and Responsibilities 15-16

Table 4. Typology of Flood Types, Characteristics and Impacts 26

Table 5. Precipitation 35

Table 6.Tabulated Computations 44

Table 7. Summary of Pipe Sizes 45

Table 8. Budget Estimation 48-49

FIGURES

Figure 1. Project Site Location 10

Figure 2. Location Map of Bistekville 1 from the Quezon City Planning

and Development Office 20

Figure 3. Topographic Survey of the Location of the Bistekville 1 from the

Quezon City Planning and Development Office 21

Figure 4. Manning’s Formula for Full Pipes 24

Figure 5. Activated Sludge Method. 27

Figure 6. Site Development Plan 31

Figure 7. Site Layout Plan 32

Figure 8.Determination of Water Requirement of the Future Tenants of Bistekville 1 46

Figure9. Project Schedule 47

1

EQUATIONS

Equation 1. Rational Method

21

Equation 2. Chezy Formula

22

Equation 3. Manning’s Formula

23

1

APPENDIX

TABLE

Rainfall Intensity Duration Frequency Table from PAGASA

1

Codes and Provisions

Here in the Philippines we have different provisions and codes that pertain to the design

and construction of sewer systems. These codes can serve as guide and helpful

information in the study.

EXCERPTS FROM THE PLUMBING LAW- AN ACT TO REGULATE THE

TRADE OF MASTER PLUMBER, R.A. 1378 (Approved, June 18, 1955)

(h) The drainage system shall be designed, constructed, and maintained so

as to guard against fouling, deposits of solids, clogging, and with adequate

so arranged that the pipes may be readily cleaned.

(k) The drainage system shall be designed to provide an adequate

circulation of air in pipes with no danger of siphonage, aspiration, or

forcing of trap seals under conditions of ordinary use. [2]

SANITATION CODE

CHAPTER XVII- SEWAGE COLLECTION AND DISPOSAL, EXCRETA

DISPOSAL AND DRAINAGE

Sec. 79.Drainage.

a. Responsibility of cities and municipalities. It shall be the

responsibility of all cities and municipalities to provide and

maintain in a sanitary state and in good repair a satisfactory

system of drainage in all inhabited areas where waste water

from buildings and premises could empty without causing

nuisance to the community and danger to public health.

b. Connection to the municipal drainage system. Buildings or

premises producing waste water shall be connected to the

municipal drainage system in all areas where it exists. [2]

DRAINAGE PROVISIONS ( WATER CODE)

CHAPTER IV – UTILIZATION OF WATERS

Art. 44. Drainage systems shall be so constructed that their outlets are

rivers, lakes, the sea, natural bodies of water, or such other water course as

may be approved by the proper government agency

1

Art. 45. When a drainage channel is constructed by a number of persons

for their common benefit, the cost of construction and maintenance of the

channel shall be borne by each in proportion to the benefits derived.

Art. 46. When artificial means are employed to drain water from higher to

lower land, the owner of the higher lands,subject to the requirements of

just compensation. [2]

WASTEWATER DISPOSALAND DRAINAGE PROVISIONS (NATIONAL

BUILDING CODE)

CHAPTER 9 – SANITATION

Sec. 904.Storm Drainage System.

(a) Rainwater drainage shall not discharge to the sanitary sewer system.

(b) Adequate provision shall be made to drain low areas in buildings and

their premises [2]

WASTEWATER PROVISIONS (NATIONAL PLUMBING CODE 1993-1994

REVISION)

CHAPTER 5 – GENERAL REGULATIONS, INSTRUCTION AND

REQUIREMENTS

Article III – Sewer Required

P-1. Every building in which plumbing fixtures are installed has a

connection to a public or private sewer except as provided in this Code.

P-2. When a public sewer is not available for use, drainage piping from

buildings and premises shall be connected to an approved private sewage

disposal system.

Article VI – Plans Required

P-1. The Provincial/City/Municipal Plumbing Official may require the

submission of plans, specifications, drawings, and such other information

as he deem necessary prior to the commencement of and at any time

during the progress if any work as regulated

.

Article XV – Trenching, Excavation and Backfill

P-4. All exaction shall be completely backfilled as soon after inspection as

practicable. Adequate precaution shall be taken to insure proper

compactness of backfill around piping without damage to such piping.

Trenches shall be backfilled in thick layer 30.48 cm (12inches) above the

top of the piping with clean earth which shall not contain stones, boulders,

cinderfill or other materials which would damage or break the piping or

1

cause corrosive action. Mechanical devices such as bulldozers, graders,

etc. may then be used to complete backfill to grade. Fill shall be properly

compacted. Suitable precautions shall be taken to insure permanent

stability for pipe and laid in filled or made ground. [2]

CHAPTER 6 – DRAINAGE SYSTEMS

Article 1 – Materials

P-1. Drainage pipe shall be cast iron, galvanaized steel, galvanized

wrought iron, lead, copper, brass, ABS, PVC, or other approved materials

having a smooth and uniform bore, except:

A. That no galvanized wrought iron or galvanized steel pipe shall be used

underground and shall be kept at least 15.24 cm (6inches) above

ground.

B. ABS or PVC installation limited building construction not more than

six or 60 feet in height [2]

The RULES AND REGULATIONS OF THE NATIONAL POLLUTION CONTROL COMMISSION FOR DOMESTIC WASTEWATER DISPOSAL

The Rules and Regulations of NPCC for domestic wastewater disposal is

an important basis in this project because it stated the requirements in

constructing, repair or renovation of sewage works. It is important to have

application for authority that is imposed by the Commission. Plans and

Specifications is the major requirement for the action on application for

authorization. [2]

CHAPTER 1. GENERAL PROVISIONS AND ADMINISTRATION

SEC. 10.Engineering Report

A. Collection System

1. Present area served, as well as future areas to be served, including

population data for each area.

2. Terrain data in sufficient detail to establish general topographical

features of present and future area to be served.

3. Minimum and maximum grades proposed.

4. Characteristics of sewage in various sections of the collection

system.

5. Flow anticipated in each sewer including infiltration (storm flow)

for the present and for ultimate development.

9. Proposed manhole spacing and the recommended maintenance and

operation procedures involved. [2]

CHAPTER III. PLANS AND SPECIFICATION

1

SEC. 16. Plans in General

(c) Detailed plans shall show : plan views, elevations, sections and

supplementary views; dimensions and relative elevations of structures;

location and outline form of equipment; location and size of piping;

water levels; ground elevations and other relevant information which,

together with the specifications and general lay-outs, will provide

working information for the construction of the works.

SEC.17. Plans of Sewers

(b) Detailed Plans and Profile- Detailed plans and profiles of sewers shall

show the following:

i. Location of streets and sewers

.

ii. Line of ground surface, size, material and type of pipe, distance

between adjacent manholes, grade and surface elevations at each

manhole and grade of sewer between each two adjacent manholes.

All manholes shall be numbered on the plans and profile.

iii. Locations of all special features such as inverted siphons,

concrete encasements, elevated sewers, etc.

iv. Special detailed drawings to show stream crossings, inverted

siphons and sewer outlets, etc.

The above plans and profile shall, as far as practicable, be prepared

using the following scales:

Horizontal Vertical

1:100 1:10

1:500 1:50

1:1000 1:100

SEC. 20. Specifications

The specifications accompanying construction drawings shall

include, but not limited to, all construction information not shown on the

drawings which is necessary to inform in detail the builder of the design

requirements as to the quality of materials and workmanship and

fabrication of the project and the types,size, strength, operating

characteristics and rating of equipment, including machinery, valves,

piping, and jointing of pipe; electrical apparatus, wiring, meters;

laboratory fixtures and equipment; construction materials; special filter

materials such as stone, sand, gravel or slag; miscellaneous appurtenances;

chemicals when used; instructions for testing materials and equipment as

necessary for meet design standards; and operating tests for the completed

works and component units.

1

CHAPTER IV – Sewers and Sewage Pumping Stations

a) Capacity of Sanitary Sewers - average daily per capita flow of sewage of not

less than 200 liters per day

b) Minimum Size - No gravity sewer conveying raw sewage shall be less than

200 mm. in diameter. The use of 150 mm. diameter pipe will be given

consideration where the design computations justify its use.

c) Slope - sewers shall be so designed and constructed as to give mean velocities,

when flowing full, of not less than 0.6 m/s based on Manning's formula using

an "n" value of 0.013

Table 4. Sewer Size – Minimum Slope

Sewer Size I.D

(in mm)

Minimum Slope

Meter/100m.

150 0.65

200 0.40

250 0.28

300 0.22

360 0.17

410 0.14

530 0.10

600 0.08

760 0.058

900 0.046

Note: For lines larger than 900 mm (36") in diameter, the slope shall be

determined by a standard recognized formula to maintain a minimum velocity of 0.6 m/s

( 2 feet per second).

d) Alignment - Sewers 600 mm. 24" or less in diameter shall be laid in straight

alignment with uniform grade between manholes

e) Change in pipe size - When a smaller sewer joins a larger one, the invert of

the larger sewer should be lowered sufficiently to maintain the same energy

gradient as in the previous pipe.

f) Manholes –

a. Manholes shall be installed at the end of each line; at all changes in

grade, size, or alignment; at all intersections; and at distances not

greater than 120 meters for sewers 380 mm in diameter or less and

150 meters for sewers 460 to 760 mm in diameter. Greater spacing

may be permitted in larger sewers.

b. The location of manholes in streams should be avoided.

1

c. A drop pipe should be provided for a sewer entering a manhole at an

elevation of 0.60 m. or more above the manhole invert. Where the

difference between the incoming sewer and the manhole invert is less

than o.60 m. the invert should be filleted to prevent solid deposition.

d. The minimum diameter of manholes shall be 900 mm; larger diameters

are preferable for large diameter sewers. A minimum access diameter

of 560 mm shall be provided.

e. Manholes shall be of pre-cast concrete, poured-in-place concrete, or

other approved water-tight types. Manholes of brick or segmented

block shall be waterproofed on the exterior with plastic coatings. [2]

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Documents

Design of Storm Sewer System for the Bistekville 1 of Brgy. Payatas Quezon City