Plumbing Design Handouts

MASTER PLUMBER REVIEW

Plumbing Design and Installation

PLUMBING CONCEPTS

Part 1: Fundamentals of Plumbing

Design and Installation

Part 2: Process, Design Criteria and

Computations

PLUMBING

• the

art and technique of installing pipes,

fixtures, and other apparatuses

in buildings

for bringing in the supply of liquids, substances

and/or ingredients and removing them; and such

• water, liquid and other carried-wastes

hazardous to health, sanitation, life and property;

also the

• pipes and fixtures after installation

PLUMBING

Plumber

– title of the person who is skilled in plumbing

Plumbarius

– who worked in the field of sanitation in

ancient Rome

Plumbum

– means lead, the material the ancient

Rome used in plumbing

C o m p o n e n t s

WATER DISTRIBUTION SYSTEM

FIRE PROTECTION SYSTEM

PLUMBING FIXTURES

SANITARY DRAINAGE SYSTEM

STORM DRAINAGE SYSTEM

FUEL GAS PIPING SYSTEM

PLUMBING SYSTEM

• Water Supply

PVC, GI, BI, PE,

HDPE, Steel,

BI – Black Iron

• Storm/Drainage System

PVC, GI/BI

• Vent System

PVC

• Sewer/Waste System

PVC, CI

Comp

on

en

ts

&

Flow

in

W

at

er

Sy

st

ems

:

SUPPLY Water Mains, Storage Tanks DISTRIBUTION Pressure, Piping Networks USE Plumbing Fixtures COLLECTION Gravity, Piping Networks TREATMENT Sewage Plants, Natural Purification SOURCE Lakes, Rivers, Reservoirs Treated water returned to the original source DISPOSAL Sanitary and Storm Sewers

NATIONAL PLUMBING CODE OF THE

PHILIPPINES

• “Book of Master Plumbers” practicing their

profession in the Philippines

• 22 Basic Principles of the Plumbing Code

• 7 Code of Ethics

NATIONAL PLUMBING CODE OF THE

PHILIPPINES

• Board Resolution No. 4, Series of 1999

• History of Plumbing Practice

• Basic Principles

• Master Plumber’s Code of Ethics

• CHAPTERS:

1. Administration

2. Definitions

3. General Regulations

4. Plumbing Fixtures

NATIONAL PLUMBING CODE OF THE

PHILIPPINES

5. Inspections and Tests

6. Water Supply and Distribution

7. Excreta Drainage System

8. Indirect Waste Piping, Wet-Vented Systems, and Special

Wastes

9. Vents and Venting

10. Traps and Interceptors

11. Storm Drainage System

12. House Drains and House Sewers

13. Joints and Connections

14. Quality of Weight Materials, Plumbing Materials and

Referenced Standards

NATIONAL PLUMBING CODE OF THE

PHILIPPINES

• Appendix A: Recommended Rules for Sizing

the Water Supply System

• Appendix B: Private Sewage Disposal

Systems

OBJECTIVES OF PLUMBING IN BUILDINGS

1. To supply water to different parts of the

building

2. To remove and discharge human wastes and

other substances out of the building into the

public sewer or septic tank

CONDITIONS FOR AN EFFECTIVE WATER SUPPLY

IN BUILDINGS

1. Provide sufficient amount of water to supply

each fixture

2. Prevent back flow of used water into the

water supply system

WATER DISTRIBUTION IN

BUILDINGS

Part 1: Fundamentals of Plumbing

Design and Installation

Part 2: Process, Design Criteria and

Computations

THINGS TO CONSIDER IN THE PLANNING OF

WATER SYSTEM IN BUILDINGS

1.

System must provide adequate supply of water, with

adequate pressure up to the extremities of the system

2.

System should be provided with sufficient valves and

blow-off’s to allow repair work without undue interruption of

service

3.

There should be no unprotected open reservoir, or cross

connections with inferior water system to enter the system

4. Water system should be tight against leakage.

Branches or connections should not be submerged

in surface water or to any source of contamination

5. System design shall afford effective circulation of

water with minimum number of dead end mains

6. System shall be guarded against contamination

resulting from repair works, replacement or

extension of the mains

7.

When new are installed, or old mains repaired, they should

be filled with strong chlorine solution of 40-60 mg/L for at

least 24 hrs., and then flushed with water supplied normally

from the main.

8.

As much as possible water main should be laid above the

elevation of concrete sanitary sewers, or crossover points,

and at least 3m horizontally from such sanitary sewer when

they are parallel. Otherwise, the sewer main must be

CLASSIFICATION OF PUBLIC WATER DISTRIBUTION

SYSTEM

1. DIRECT PRESSURE DISTRIBUTION

2. INDIRECT PRESSURE DISTRIBUTION

• DIRECT PRESSURE DISTRIBUTION

– Obtain its water supply through a large intake pipe,

installed in the lake basin extended down the water;

– Water is then drawn from the lake to a receiving well by

force of gravity, passing through the filtration plant

– The water inside the reservoir is pumped by a centrifugal,

or piston pump into the water main with sufficient

• INDIRECT PRESSURE DISTRIBUTION

– Water drawn from a drilled distribution is done by indirect

pressure using a turbine pump mounted on top of the

HOUSEHOLD WATER SUPPLY

Water is conveyed from the main to the

household or buildings through:

1. House Service

2. Riser

House Service

 pipe connection from the water main to any source

of water supply to the building served

Riser

 Vertical supply pipe which extend upward from one

floor to the next.

Branches

Water Main Corporation Stop Stop Box Curb Stop Meter Stop

House Service Pipe

Water Meter

Corporation Stop or Cock

Curb Stop

Meter Stop

Water Main

refers to the public water connection which are laid underground

along the streets where the house service is connected

Corporation Stop

serves as a control of the water service, and a shut-off

when service is disconnected

Curb Stop

installed between the curb & the sidewalk line to serve

as control stop of the service between the curb and the

building

Meter Stop

controlling stop of the entire water supply of

the building

Water Meter

device used to measure the amount of water

that passes through the water service

TYPES OF COLD WATER SYTEM

1. NORMAL PRESSURE FROM THE PUBLIC MAIN

2. OVERHEAD FEED SYSTEM

Overhead Feed System

This supplies water to plumbing fixtures by

means of gravity.

Advantages:

1. Water supply distribution is not affected by the peak

load hour even if pressure at water main is low.

2. Power interruptions doesn’t affect water supply

3. During break down of pumps and their repairs, water

supply is not affected.

Disadvantages:

1. Water inside tank is exposed to the natural elements of

weather, subject to contamination

2. Water distribution unit has many working parts that

require higher maintenance cost

3. Pumping unit and the entire installation throughout

the building occupies valuable spaces.

4. Requires stronger foundation and other structures to

sustain heavy load of the tank and its water content

– Used on tall buildings that could not be served by the street

main

– Operates in sequence according to the volume of demand:

• When water demand is small, small (jockey) pump

operates;

• As water demand increases, the 2

nd

_{larger pump starts}

automatically to replace operation of the small pump

• For peak demands, the largest pump operates with full

capacity to supply the entire building

• Only one pump operates at a time depending on the

volume of water demand

Advantages

1. Eliminate the construction of large house water

tank

2. Avoid cost of heavy structures to carry the house

tank

– Distribution system where compressed air is used

as the delivery agent

Advantages:

1. Has compact pumping system requiring limited

space

2. Water chamber being air-tight makes the system as

sanitary one

3. Oxygen in the CA serves as purifying agent making

water more palatable

Advantages

4

Economical because it uses small pipe & fitting

sizes; less maintenance/construction cost

5

Acceptable to small and tall buildings

Disadvantage:

4 Mechanical Devices used in Air Pressurized

Water Supply System

1. Storage Tank

2. Single or Duplex centrifugal pump

3. Air compressor

Friction in Water Supply

the resistance produced by the flowing water

with the fittings and interior surface of the pipe

How to minimize friction:

1. Pipes should be installed straight and direct

2. Use of fittings, stops, turns, offset and traps

should be minimized

3. Pipes with plain and smooth surface should be

used

Normal Pressure

refers to the pressure range measured over 24 hours

Normal Pressure

30-40 psi

Pressure Lower than Normal Pressure

Pressure greater than 50 psi

may cause pipe hammering or even bursting of pipes

Pressure Reducing Valve

valve used to avoid excessive water pressure by

keeping pressure constant at 40 psi or can be reset to

other pressure desired

Critical Pressure

maximum and minimum pressure at which proper

function of the water supply can be maintained

MAXIMUM PROBABLE DEMAND

• Refers to the MAXIMUM WATER DISCHARGE OF

FIXTURES in terms of Fixture units

• THE MAXIMUM DEMAND OF WATER is equal to the

TOTAL FIXTURES UNITS in the plumbing system

• One unit is valued at 8 gals of water discharge per

minute interval

Illustration:

A residential house has 3 water closets, 3

lavatories, 1 kitchen sink, and 3 shower baths.

Determine the maximum demand.

PROBABLE DEMAND

OR PEAK LOAD

The fewer the number of fixtures installed,

the higher the percentage of probability of their

simultaneous use;

The greater the number of fixtures installed,

the lower the percentage of probable simultaneous

use.

PROBABILITY OF SIMULTANEOUS OF FIXTURES

Number of Fixtures

% of Simultaneous Use

1 to 5

50% to 100%

6 to 50

25% to 50%

51 or more

10% to 25%

PROBABLE DEMAND does not exceed 25% of the

Maximum Water Demand

Illustration:

Determine the probable demand of the following

Fixtures installed: 2 water closets, 1 lavatory, 1

bathtub, 1 shower valve, 1 kitchen sink.

TYPES OF HOT WATER SYTEM

1. UPFEED AND GRAVITY RETURN SYSTEM

2. DOWNFEED AND GRAVITY RETURN SYSTEM

3. PUMP CIRCUIT SYSTEM

With a continuing network of pipes to provide constant circulation of water

Hot water rises on its own & does not need any pump for circulation

Hot water is immediately

drawn form the fixture any time Provided economical circulating return of unused hot water

Larger pipe is installed at the

top of the riser & the diminishing sizes passes through the lower floors of the building

Hot water rises on to the highest point of the plumbing system and travels to the fixtures via gravity (closed pipe system) Water distribution is dependent on the expansion of hot water & gravity.

Larger pipe is installed at the bottom of the riser & the diminishing sizes passes

through the upper floors of the building

For a more efficient circulation of hot water to the upper floor levels of multi-storey buildings

Water Tanks & Cisterns

Hot Water Consumption

KIND OF BUILDING

GALLONS PER PERSONS PER HOUR

Office Buildings School Buildings Apartment Buildings Hotels Factories Residential 4 to 5 2 to 3 8 8 to 10 4 to 6 10

Working Load of Hot Water Systems

KIND OF BUILDING AVERAGE WORKING LOAD

School, Office & Industrial types Apartments & Residences

Hotels & Restaurants

25% 35% 50%

Hot Water Space Heating System

Hot Water Supply System

Water is confined within a system at low temperature

Not a closed system which operate on much higher temperature

Protection of Hot Water Tank:

System Relief Valve

Temperature & Pressure Relief

Used for Hot Water Space Heating System

Used for Hot Water Supply System

FLUID COMPUTATIONS

Part 1: Fundamentals of Plumbing

Design and Installation

Part 2: Process, Design Criteria and

Computations

Water

/

Wastewater

Example:

Convert cubic feet to gallons.

Gallons = Cubic Feet (ft

3

_{) x gal/ft}

3

Problem

How many gallons of biosolids can be pumped to a

digester that has 3600 cubic feet of volume available?

Convert gallons to pounds.

pounds ( lb ) = Gallons (gal) x 8.34 lb/gal

Problem

If 1650 gallons of solids are removed from the primary

settling tank, how many pounds of solids are removed?

Convert milligrams/liter to pounds.

 key point: For plant operations, concentrations in milligrams

per liter (mg/L) or parts per million (ppm) determined by

laboratory testing must be converted to quantities of pounds,

kilograms, pounds per day, or kilograms per day.

Pounds = Concentration (mg/L) x volume (MG)

x 8.34 lb/mg/L/MG

Problem

The solids concentration in an aeration tank is 2580 mg/L. The

aeration tank volume is 0.95 MG. How many pounds of solids are

in the tank?

Convert milligrams per liter to pounds per day.

Pounds/day = Concentration (mg/L) x flow (MGD)

x 8.34 lb/mg/L/MG

Problem

How many pounds of solids are discharged per day when the plant

effluent flow rate is 4.75 MGD and the effluent solids concentration

is 26 mg/L?

Convert milligrams per liter to kilograms per day.

kg/day = Concentration (mg/L) x volume (MG)

x 3.785 kg/mg/L/MG

Problem

The effluent contains 26

mg

/

L

of

BOD₅

. How many kilograms per day

of

BOD₅

are discharged when the effluent flow rate is 9.5

MGD

?

Convert million gallons per day (MGD) to

gallons per minute (gpm).

Flow = Flow (MGD) x 1,000,000 gal/MG

1440 min/day

Problem

The current flow rate is 5.55 MGD. What is the flow rate in gallons

per minute?

Convert million gallons per day (MGD) to gallons per day (gpd)

Flow = Flow (MGD) x 1,000,000 gal/MG

Problem

The influent meter reads 28.8 MGD. What is the current flow rate

in gallons per day?

Convert million gallons per day (MGD) to cubic feet per

second (cfs)

Flow (cfs) = Flow (MGD) x 1.55 cfs/MGD

Problem

The flow rate entering grit channel is 2.89 MGD. What is the flow

rate in cubic feet per second?

Problem

A liquid chemical with a specific gravity (SG) of 1.22 is pumped at a

rate of 40 gpm. How many pounds per day are being delivered by the

pump?

Temperature Conversions

Most water/wastewater operators are familiar with the formulae

used for Fahrenheit and Celsius temperature conversions:

o

_{C = 5/9 (}

o

_{F – 32)}

o

_{F = 9/5 (}

o

_{C) + 32}

The difficulty arises when one tries to recall these formulae from

memory. Probably the easiest way to recall these important formulae

is to remember three basic steps for both Fahrenheit and Celsius

conversions:

 Add 40

o

 Multiply by the appropriate fraction (5/9 or 9/5)

 Subtract 40

o

Suppose that we wish to convert 240

o

_{F to Celsius. Using the}

three-step process, we proceed as follows:

• Step 1 :

add 40

o

240

o

_{+ 40}

o

_{= 280}

o

• Step 2 :

multiply 280

o

_{by either 5/9 or 9/5.}

Because the conversion is to the Celsius scale, we will be moving to a

number smaller than 280. Through reason and observation, obviously, if 280 were multiplied by 9/5, the result would be almost the same as multiplying by 2, which would double 280 rather than make it smaller. If we multiply by 5/9, the result will be about he same as multiplying by ½. Because in this problem we wish to move to a smaller number, we should multiply by 5/9:

(5/9) (280

o

_{) = 156.0}

o

_C

• Step 3 :

now subtract 40

o

_.

156.0

o

_{- 40}

o

_{= 116.0}

o

_C

Convert 22

o

_{C to Fahrenheit.}

FLOW

Flow is expressed in many different terms in the English system of measurement. The most commonly used flow terms are as follows:

• gpm – gallons per minute

• cfs – cubic feet per second

• gpd – gallons per day

• MGD – million gallons per day

In converting flow rates, the most common flow conversions are 1 cfs = 448 gpm and 1 gpm = 1440 gpd. To convert gallons per day to MGD, divide the gpd by 1,000,000. For example, convert 150,000 gallons to MGD:

150,000 gpd = 0.150 MGD 1,000,000

In some instances, flow is given in MGD but is needed in gpm.

To make the conversion (MGD to gpm), two steps are required.

•

Step 1:

convert the gpd by multiplying by 1,000,000.

•

Step 2:

convert to gpm by dividing by the number of minutes in

a day (1440 min/day).

Problem

Convert 0.135 MGD to gpm.

In determining flow through a pipeline, channel, or stream, we

use the following equation:

where

Q = cubic feet per second (cfs)

V = velocity in feet per second (ft/second)

Problem

Find the flow in cubic feet per second (cfs) in an 8-inch line if the velocity is 3 feet per second.

Problem

Find the flow in gpm when the total flow for the day is 75,000 gpd.

Problem

Find the flow in gpm when the flow is 0.45 cfs.

DETENTION TIME

Detention time is the length of time water is retained in a vessel

or the period from the time the water enters a settling basin until

it flows out the other end. When calculating unit process

detention times, we are calculating the length of time it takes the

water to flow through that unit process. Detention times are

normally calculated for the following basins or tanks:

•

Flash mix chambers (seconds)

•

Flocculation basins (minutes)

•

Sedimentation tanks or clarifiers (hours)

•

Wastewater ponds (days)

To calculate the detention period of a basin, the volume of the

basin must first be obtained. Using a basin 70 ft long (L), 25 ft wide

(W), and 12 ft deep (D), the volume (V) would be:

V = L x W x D

V = 70 ft x 25 ft x 12 ft

V = 21,000 ft3

Gallons = V x 7.48 gal/f2

Gallons = 21,000 x 7.48 = 157,080 gallons

If we assume that the plant filters 300 gpm, then we have

157,080 / 300 = 524 minutes, or roughly 9 hours, of detention

time. Stated another way, the detention time is the length of time

theoretically required for the coagulated water to flow through the

basin.

 Key point: If the detention time is desired in minutes, then the flow rate used in the calculation should have the same time frame (cfm or gpm, depending on

whether tank volume is expressed as cubic feet or gallons). If detention time is desired in hours, then the flow rate used in the calculation should be cfh or gph. If chlorine is added to the water as it enters the basin, the chlorine contact time (CT) would be 9 hours. That is, to determine the CT (concentration of free chlorine residual x disinfectant contact time [in minutes] used to determine the

effectiveness of chlorine), we must calculate detention time.

 Key point: True detention time is the T portion of the CT value.

Detention time, of course, is calculated in units of time. The most common are seconds, minutes, hours, and days. Examples of detention time equations where time and volume units match include:

Detention time (sec) = volume of tank (cu ft) flow rate (cfs)

The simplest way to calculate detention time is to divide the volume of the container by the flow rate into the container. The theoretical detention time of a container is the same as the amount of time it would take to fill the

container if it were empty. For volume, the most common units used are

gallons; however, on occasion, cubic feet may also be used. Time units will be in whatever units are used to express the flow. For example, if the flow is in gpm, the detention time will be in days, If, in the final result, the detention time is in the wrong time unit, simply convert to the appropriate units.

Detention time (days) = volume of tank (gal) flow rate (gph)

Problem

The reservoir for the community holds 110,000 gallons. The well

will produce 60 gpm. What is the detention time in the reservoir in

hours?

Problem

Find the detention time in a 55,000-gallon reservoir if the flow rate

is 75 gpm.

HORSEPOWER AND ENERGY COSTS

In water/wastewater treatment and ancillaries, horsepower is a

common expression for power. One horsepower is equal to 33,000

foot pounds (ft-lb) of work per minute. This value is determined,

for example, for selecting the pump or combination of pumps to

ensure an adequate pumping capacity (a major use of calculating

horsepower in water/wastewater treatment). Pumping capacity

depends upon the flow rate desired and the feet of head against

which the pump must pump (also referred to as effective height).

Calculations of horsepower are made in conjunction with many

treatment plant operations. The basic concept from which the

horsepower calculation is derived is the concept of work, which

involves the operation of a force (lb) over a specific distance (ft).

The amount of work accomplished is measured in foot-pounds:

The rate of doing work (power) involves a time factor. Originally,

the rate of doing work or power compared the power of a horse to

that of a steam engine. The rate at which a horse could work was

determined to be about 550 ft-lb/sec (or 33,000 ft-lb/min). This

rate has become the definition of the standard unit called

Horsepower (hp)

Horsepower (hp) = power (ft-lb/min) 33,000 ft-lb/min/hp

As mentioned, in water/wastewater treatment the major use of horsepower calculation is in pumping stations. When used for this purpose, the horsepower calculation can be modified as shown below.

Water Horsepower (whp)

• The amount of power required to move a given volume of water a specified

total head is known as water horsepower.

whp = pump rate (gpm) x total head (ft) x 8.34 lb/gal 33,000 ft-lb/min/hp

Problem

A pump must deliver 1210 gpm to a total head of 130 feet. What is the

required water horsepower?

Brake Horsepower (bhp)

• Brake horsepower (bhp) refers to the horsepower supplied to the pump from

the motor. As power moves through the pump, additional horsepower is lost from slippage and friction of the shaft and other factors; thus, pump efficiencies range from about 50% to 85%, and pump efficiency must be taken into account.

bhp = whp

Problem

Under the specified conditions, the pump efficiency is 73%. If the

required water horsepower is 40 hp, what is the required brake

horsepower?

Motor Horsepower (mhp)

• Motor horsepower (mhp) is the horsepower the motor must generate to

produce the desired brake and water horsepower.

mhp = brake horsepower motor efficiency (%)

Problem

The motor is 93% efficient. What is the required motor

horsepower when the required brake horsepower is 49.0 bhp?

ELECTRICAL POWER

On occasion, water/wastewater operators (especially senior

operators) must make electrical power calculations – especially

regarding electrical energy required/consumed during a period of

time. To accomplish this, horsepower is converted to electrical

energy (kilowatts), then multiplied by the hours of operation to

obtain kilowatt-hours.

Problem

A 60-horsepower motor operates at full load 12 hours per day, 7

days a week. How many kilowatts of energy does it consume per

day?

Given the cost per kilowatt-hour, the operator (or anyone else) may calculate the cost of power for any given period of operation.

Cost = power required/day x kW-hr/day x days/period x cost/kW-hr

PD 856

Chapter 17 - Sewage Collection and

Disposal, Excreta Disposal and

Drainage

Part 1: Fundamentals of Plumbing

Design and Installation

Part 2: Process, Design Criteria and

Computations

Section 3: Individual Excreta and

Sewage Disposal System

3.1 Individual Excreta Disposal System

•

Every plan and specifications for excreta disposal

system approved by the local health authority prior

to construction.

•

The City/Municipal Building Official shall refer all

applications for Sanitary (Plumbing) Permit to the

Local Health Authority prior to issuance of building

permit.

•

The privy recommended for use is the sanitary

privy.

•

The sanitary privy shall be atleast one (1) meter

square.

Section 3: Individual Excreta and

Sewage Disposal System

3.2 Individual Sewage Disposal System

3.2.1 Installation Requirements

•

When a public sanitary sewer is not available,

wastewater piping shall be provided with individual

sewage disposal system of approve type and

design.

•

The public sanitary sewer may be considered as

not being available when such public sanitary

sewer is located more than 100 meters from any

proposed building on any lot or premises.

Section 3: Individual Excreta and

Sewage Disposal System

3.2 Individual Sewage Disposal System

3.2.2 Approval

•

The Local Health Authority may require any or all of the

following information before Sanitary (Plumbing) Permit is

issued.

– Plot plan drawn to scale completely dimensioned, showing direction and approx slope of surface

– Location of all present and proposed retaining walls, drainage channels, water supply lines and wells

– Number of plumbing fixtures

– Location of building sanitary sewer and individual sewage disposal system

– A log of soil formations and ground water levels, together with a statement of water absorption characteristics of the soil

Section 3: Individual Excreta and

Sewage Disposal System

3.2 Individual Sewage Disposal System

3.2.2 Disposal of Sewage

•

Individual sewage disposal system utilizing leaching fields,

leaching beds, or leaching wells shall not be permitted where

the depth to normal ground water or rock strata is less than

1.20 meters

•

A leaching system shall not be installed in an area where the

texture, structure, and porosity of soil are not suitable as

determined by a percolation test performed by a registered

Civil/Sanitary Engineer.

•

No leaching tile file or bed shall be installed where percolation

rate is less than 2.54 cm fall in water level in test holes in 60

minutes.

•

No seepage pit or leaching well shall be installed where

percolation rate is less than 2.54 cm fall in water level in test

holes in 30 minutes.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.1 Septic Tank

4.1.1 Design Capacity

•

May be determined from the quantities of Sewage

Flow, based on adequate detention time interval

resulting in efficient sedimentation.

•

For building with occupants, the number of

persons to be served shall be computed based on

the number of rooms and considering each room

as occupied by two persons or on basis of the

actual number of persons served by the tank,

whichever is greater.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.1 Septic Tank

4.1.2 Inlet and Outlet

•

The invert level of the inlet shall

not be less than 5 cm

above the liquid level

of the septic tank.

•

A vented inlet baffle or sanitary tee shall be provided to

divert the incoming sewage downward. The baffle or tee

shall penetrate

at least 15 cm below the liquid level

, but the

penetration shall not be greater than that allowed for the

outlets baffle or sanitary tee.

•

The outlet baffle or sanitary device shall extend through the

scum layer above the liquid level of the tank to

approximately

2.5 cm from the inside top of the tank

.

•

The invert of the inlet pipes shall be at a level

not less than

5 cm above the invert of the outlet pipe

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.1 Septic Tank

4.1.3 Tank Proportions

•

If two or more compartments are used, the first

compartment shall have the capacity from

one-half

to two-thirds

of the

total volume of the tank

.

•

The septic tank shall have a liquid drawing

depth

not less than 1.20 meters (4 feet)

.

•

The vertical distance from the liquid level to the

inside top of the tank shall be

at least 20 cm (8in)

.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.1 Septic Tank

4.1.4 Inspection Manholes

•

Shall be provided with an inspection

manhole 0.36

sq.m. (4 sq.ft.)

in minimum area or by equivalent

removable cover slab to provide access to the inlet

and outlet devices and to the compartment of the

tank for inspection and cleaning.

•

Septic tanks installed under concrete or block top

paving shall have the required manholes accessible

by extending the manhole openings to grade.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.1 Septic Tank

4.1.5 Construction of Septic Tank

4.1.6 Location

•

Shall be located not less than

25 meters

from any

well, spring, cistern

, or other

sources of drinking water supply; not less

than

1.5 m from any water service line

; and

not less than 3.0 meters away from water

main

.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.1 Septic Tank

4.1.7 Maintenance

•

Shall be inspected

at least once a year

and be

cleaned when the bottom of the scum mat is

within

3 inches of the bottom

of the outlet device

or the sludge and scum has reduced the

liquid

capacity by 50%

.

•

Tanks shall not be washed or disinfected after

cleaning. A small residual of sludge shall be left in

the tank for seeding.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.2 Leaching Tile Field

4.2.1 Design

•

_{A leaching tile system utilizing trenches}

0.45-0.90 m wide

is considered to be a leaching

tile field.

•

A leaching tile system utilizing trenches

more than

0.90 m wide

is considered to be a

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.2 Leaching Tile Field

4.2.2 Construction

•

_{The leaching tile field or leaching bed shall}

be located not less than

25 meters from any

well, spring, cistern, or other source of

drinking water supply

;

not less than 3 meters

from an occupied building

; and

not less than

1.5 meters from any lot line

.

Section 4: Design and Construction of Septic

Tanks, Leaching Tile Field and House Sewers

4.3 House Sewers

4.3.1 Design

•

_{Minimum size shall}

_{not be less than 100mm}

Section 5: Public Sewerage System

5.2 Provision of Sewerage System

5.2.2 Operation of Sewage Treatment Plants

a.

The sewage treatment plant shall be capable of

treating the flow of sewage discharged by the

community in the area.

b.

The type of sewage treatment plant shall be approved

by the Secretary or his duly authorized representative

and the effluent from such treatment plants shall meet

the standards formulated by the Department of

Environment and Natural Resources.

c.

The sewage treatment plant shall provide laboratory

facilities for control tests and other examinations

needed.

Section 5: Public Sewerage System

5.2 Provision of Sewerage System

5.2.2 Operation of Sewage Treatment Plants

d. Operating data, control tests and such other

records as may be required shall be forwarded to

the local health authority.

e. The local health authority shall be informed in case

of breakdown or improper functioning of the

treatment works.

f.

Where sewage treatment plant is provided, no

sewage shall be allowed to by-pass the plant.

g. The sewage treatment plant shall be managed by a

registered sanitary engineer.

Section 6: Damage to Public Sewer or

Sewage Disposal System

6.1 It is unlawful for any person to discharge

anything which would cause damage to the

public sewage disposal system, whether the

system is government or privately-owned.

Effectivity

• IRR of the Chapter 17 of PD 856 was approved

on December 21, 1995

Private Sewage Disposal Systems

Definition: (SEPTIC TANK)

A watertight covered receptacle designed and constructed to

receive

the discharge of sewage from a building sewer,

separate

solids from the liquid,

digest

organic matter and

store

digested solids through a period of detention, and allow the clarified liquids to

discharge

for final disposal

SLUDGE

- solid organic matter that are denser than water and

settle at the bottom of the septic tank

SCUM

- lighter organic material that rise to the surface of the

water

EFFLUENT

- liquid content of sewage

DISPOSAL PHASE- the final stage of the plumbing process; where used water and water-carried wastes are brought to various

Bacteria in septic tank

to encourage decomposition

:

Aerobic bacteria-

relies on oxygen to survive

Anaerobic bacteria-

can survive in places without oxygen

Minimum

Dimensions:

L= 1500mm W=900mm D=1200mm

SEPTIC TANK

SINGLE CHAMBER SEPTIC TANK:

should show all dimensions, reinforcing, structural calculations, and such other pertinent data as needed.

DESIGN CRITERIA:

PLANS:

shall be such as to produce a clarified effluent of acceptable

standards and shall provide adequate space for sludge and scum accumulations.

QUALITY OF DESIGN:

constructed of durable materials, not subject to excessive corrosion or decay, shall be watertight.

MATERIALS:

Material: cement (most common) or pre-fabricated cast iron

have a minimum of 2 compartments:

First compartment: not less than 2/3 capacity of the total capacity of tank; not less than 2 cum liquid capacity; shall be at least 0.9 m width and 1.5 m long; Liquid depth not less than 0.6 m nor more than 1.8 m.

Secondary compartment: maximum capacity of 1/3 total capacity of tank; minimum of 1 cum liquid capacity

COMPARTMENTS:

In septic tanks having over 6 cum capacity, the secondary compartment should be not less than 1.5 m in length.

with at least two (2) manholes, 508 mm in min dimension; one over inlet, other over outlet. Wherever first compartment

exceeds 3.7 m in length, an additional manhole required over the baffle wall.

MANHOLES:

maintain a slope of 1:10 at the bottom of the digestion chamber to collect the sludge and make it easily accessible from the

manhole

Inlet and Outlet pipes – diameter size not less than the sewer pipe

SIZES OF PIPE INLET & OUTLET & THEIR VERTICAL LEGS:

Vertical legs of inlet and outlet pipes – diameter size not less than the sewer pipe nor less than 104.6 mm.

Shall extend 101.6 mm above and at least 304.8 mm below the water surface

LENGTH AND LOCATION OF INLET & OUTLET:

Invert of the inlet pipe shall be at a level not less than 50.8 mm above the invert of the outlet pipe.

equal to the cross sectional area of the house sewer.

VENT DIAMETER:

Side walls shall extend 228.6 mm above liquid depth.

AIR SPACE:

Cover of septic tank shall be at least 50.8 mm above the back vent openings.

PARTITION

(between compartments)

:

An inverted fitting equivalent in size to the tank inlet, but in no case less than 104.6 mm in diameter, shall be installed in the inlet compartment side of the baffle with the bottom of the fitting

placed midway in the depth of the liquid. Wooden baffles are prohibited.

Shall be capable of supporting an earth load of not less than 14.4 kPa

STRUCTURE:

The capacity of septic tanks is determined by the number of bedrooms or apartment units in dwelling occupancies; by the estimated waste/sewage design flow rate for various building occupancies; or by the number of fixture units of all plumbing fixtures; whichever is greater.

CAPACITY:

The capacity of any one septic tank and its drainage system shall also be limited by the soil structure classification in its drainage field.

Should not be located underneath the house

LOCATION:

At least 15 meters from the water distribution system

Isometric View

of a Typical

Drainage

System with

Septic Tank

System

Private sewage disposal system common in rural areas for structures with large adjacent open fields

No excavation for leach bed shall extend within 1.5 m of the water table.

DISTANCE FROM WATER TABLE:

WITH SEEPAGE PIT:

Filter material in the trenches shall terminate 1.5 m from pit excavation and the pipe extending from such points to the seepage pit shall be watertight.

dependent on the required septic tank capacity or estimated sewage flow rate, whichever is greater, and;

the type of soil found in the excavation.

AREA:

based on the quantity of liquid waste and on the character and porosity of the surrounding soil.

CAPACITY:

Circular in shape with excavated diameter of not less than 2.2 m and to be lined with clay or concrete brick.

SIZE OF SEEPAGE PIT:

a loosely lined excavation in the ground, which receives the discharge of a septic tank; designed to permit effluent to seep through pit bottom and sides

Brick lining shall have a minimum compressive strength of 17225 kPa.

STRENGTH:

served through a distribution box or shall be connected in series by means of a watertight connection. The outlet shall

have a vented leg fitting extending 304.8 mm below the inlet fitting.

MULTIPLE SEEPAGE PITS:

a non-watertight lined excavation in the ground which receives the discharge of a sanitary drainage system, designed to retain the organic matter but permitting the liquid to seep through the pit bottom and sides

Temporary expedient pending the construction of a public sewer, so long as it is established that a public sewer will be available in less than 2 years and the soil and ground water conditions are favorable;

TEMPORARY PERMITS:

As an overflow facility when installed in conjunction with an existing cesspool;

As a means of sewage disposal for limited, minor, or temporary uses.

Outside Privy- oldest form of disposal of

organic waste. Consists of a vault constructed of concrete for the collection of raw sewage and a wooden shelter

When liquid wastes containing excessive amounts of grease,

garbage, flammable wastes, sand, or other ingredients which may affect the operation of a private sewage disposal system, an

interceptor for such waste shall be installed.

REQUIREMENTS:

Waste from interceptors may be discharged to a septic tank or other primary system or into a separate disposal system.

DISPOSAL:

COMMERCIAL/INDUSTRIAL SPECIAL LIQUID

WASTE DISPOSAL

GENERAL GUIDELINES FOR PRIVATE SEWAGE DISPOSAL

SYSTEMS

Location of Sewage Disposal System

MIN. HORIZONTAL DISTANCE IN CLEAR REQUIRED FROM BLDG SEWER SEEPAGE PIT OR CESSPOOL SEPTIC TANK 1 Buildings or structures* 0.6 m 1.5 m 2.4 m 2.4 m 2 Property line Adjoining private Property Clear** 1.5 m 1.5 m 2.4 m 3 Water supply wells 15.2 m 15.2 m 30.5 m 45.7 m 4 Streams 15.2 m 15.2 m 15.2 m 30.5 m 5 Trees - 3 m - 3 m

Private Sewage Disposal Systems

DISPOSAL FIELD

Location of Sewage Disposal System

MIN. HORIZONTAL DISTANCE IN CLEAR REQUIRED FROM BLDG SEWER DISPOSAL FIELD SEEPAGE PIT OR CESSPOOL SEPTIC TANK 6 Seepage pits or Cesspools - 1.5 m 1.5 m 3.7 m 7 Disposal field 1.5 m 1.2 m 1.5 m 8 On site domestic

Water service line 0.3 m 1.5 m 1.5 m 1.5 m 9 Pressure public

Water main 3 m 3 m 3 m 3 m

Private Sewage Disposal Systems

GENERAL GUIDELINES FOR PRIVATE SEWAGE DISPOSAL

SYSTEMS

Sewage Treatment Plan (STP)

An aeration system within the tank;

Some features of STP:

A submersible mixer to mix the waste;

A sludge waste pump that aids in clarifying; A decanter;

Blowers;

DESIGN OF GREASE TRAP

Part 1: Fundamentals of Plumbing

Design and Installation

Part 2: Process, Design Criteria and

Computations

MASTER PLUMBER REVIEW

Plumbing Design and Installation