Plumbing Notes 1

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CHAPTER 1: ELEMENTS OF PLUMBING

PLUMBING

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 pipes and fixtures after installation i.e., the ‘plumbing system’. (Section 217.6 The Revised National Plumbing Code of the Philippines 1999)

PLUMBING SYSTEM

Plumbing System includes all potable water supply and distribution pipes, all plumbing fixtures and traps; all sanitary and storm drainage systems; vent pipes, roof drains, leaders and downspouts; and all building drains and sewers, including their respective joints and connections; devices, receptacles, and appurtenances within the property; water lines in the premises; potable, tap, hot and chilled water piping; potable water treating or using equipment; fuel gas piping; water heaters and vents for same. (Section 217.12 NPC 1999)

A Plumbing system, reduced to its simplest terms, consists of a supply pipe leading to a fixture and a drainpipe taking the used water away from this fixture.

The system constitutes the following:

1. The water supply and water distribution system. Carries water from the water source, street main or a pump to the building and to various points in the building at which water is used.

2. The plumbing fixtures. The receptacles that receive the supplied water and allow the occupants of the building to use the water.

3. The drainage system. The piping network within the building which conveys from the plumbing fixtures all wastes and fecal matter (sanitary drainage) as well as rainwater (storm drainage) to a point of disposal or a treatment facility.

THE PLUMBER

The plumber is the one who works or engages in the business of installing in buildings the pipes fixtures and other apparatus for bringing in the water supply and removing liquid and waterborne wastes.

There are three categories of plumbers based upon their graces of experiences. They are:

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1. Apprentice plumber- a beginner at the trade who usually serves for 3 to 5 years as helper to a journeyman.

2. Journeyman plumber- has served his apprenticeship and is competent to perform the tasks of installing and repairing plumbing.

3. Master plumber- a person technically and legally qualified and licensed to practice the profession of master plumbing without limitations in accordance with Republic Act 1378, having passed the examinations conducted by the Professional Regulation Commission (PRC), has received a certificate of registration from the board of master plumbing and possesses the current license to practice. (Section 214.5 NPC 200)

THE PLUMBING CODE

The improper installation of plumbing may affect the health of the occupants of a building and create a center point for the spread of disease. The possibility is of sufficient public interests to require the regulation of plumbing by law. The right of the government to regulate the details of plumbing is based on the principle of the protection of public health.

The basic goal of the National Plumbing Code of the Philippines is to ensure the qualified observance of the latest provision of the plumbing and environmental laws.

THE BASIC PRINCIPLES GOVERNING THE NATIONAL PLUMBING CODE

1. All premises intended for human use or habitation shall be provided with a supply of pure and wholesome water, neither connected to unsafe water supply nor subject to backflow or back- siphonage.

2. Plumbing fixtures, devices and appurtenances shall be supplied with water in sufficient volume and pressure adequate to function satisfactorily and without undue noise.

3. Plumbing shall be designed and adjusted to use the minimum quantity of water consistent with proper performance and cleaning.

4. Devices for heating and storing water shall be so designed and installed as to prevent dangers from explosion through overheating.

5. Every building abutting on a street, alley or easement with a public sewer shall connect its plumbing fixtures to the sewer system.

6. Each family dwelling unit shall have at least one water closet, one kitchen type sink, a lavatory and a bathtub or shower to meet the basic requirements of sanitation and personal hygiene.

7. Plumbing fixtures shall be made of smooth non-absorbent material, free from concealed fouling surfaces and shall be located in ventilated enclosures.

8. The drainage system shall be designed, constructed and maintained to safeguard against fouling, deposit of solids, clogging and with adequate cleanouts so arranged that the pipes may be readily cleaned.

9. All piping shall be of durable NAMPAP-approved materials, free from defective workmanship, designed and constructed by Registered Master Plumbers to ensure satisfactory service.

10. Each fixture directly connected to the drainage system shall be equipped with a water-sealed trap.

11. The drainage pipes piping system shall be designed to provide adequate circulation of air free from siphonage, aspiration or forcing of trap seals under ordinary use.

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12. Vent terminals shall extend to the outer air and installed to prevent clogging and the return of foul air to the building.

13. Plumbing systems shall be subjected to such tests to effectively disclose all leaks and defects in the workmanship.

14. Substance which will clog the pipes, produce explosive mixtures, destroy the pipes or their joints or interfere unduly with the sewage-disposal process shall not be allowed to enter the building drainage system.

15. Proper protection shall be provided to prevent contamination of food, water, sterile goods and similar materials by backflow of sewage. When necessary, the fixture, device or appliance shall be connected indirectly with the building drainage system.

16. No water closet shall be located in a room or compartment which is not properly lighted and ventilated.

17. If there is no sewer system in the area, suitable provision shall be made for the disposal of building sewage by some accepted method of sewage treatment and disposal, such as a septic tank.

18. Where a plumbing drainage system may be subject to backflow of sewage, suitable provision shall be made to prevent its overflow in the building.

19. Plumbing systems shall be maintained in serviceable condition by Registered Master Plumbers.

20. All plumbing fixtures shall be installed properly spaced, to be accessible for their intended use.

21. Plumbing shall be installed with due regard to the preservation of the strength of structural members and the prevention of damage to walls and other surfaces through fixture usage.

22. Sewage or other waste from plumbing systems, which may be deleterious to surface or sub-surface waters shall not be discharged into the ground or into any waterway, unless first rendered innocuous through subjection to some acceptable form of treatment.

BRIEF HISTORY OF PLUMBING PRACTICE IN THE PHILIPPINES

In 1902, the Plumbing Trade was duly recognized by the government in the City of Manila. Master Plumber John F. Haas became the first Chief of the Division of Plumbing Construction and Inspection. A Plumbing Code based on the Plumbing Code of the United States was incorporated into the Building Code for the City of Manila.

In 1935, the National Master Plumbers Association of the Philippines (NAMPAP) was formally organized

Manila City Ordinance 2411, the “Plumbing Code of the City of Manila” was enacted and placed under the Department of Public Services, Manila.

In 1954, the Third Congress approved House Bill No. 962 which in June 18, 1955, became R.A. 1378 “Plumbing Law of the Philippines” upon ratification of President Ramon Magsaysay.

On January 28, 1959, the National Plumbing Code of the Philippines prepared by NAMPAP was promulgated and approved by Malacañang.

Before Martial Law in 1972, Republic Act No. 6541 otherwise known as the “Building Code of the Philippines” was passed with the “National Plumbing Code of 1959” as referral code in full text.

The Professional Regulation Commission (PRC) adopted the Revised Plumbing Code of 1999 which President Joseph Estrada approved December 21, 1999 pursuant to Section 4 of R.A. 1378 known as the Plumbing Law.

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TYPICAL PLUMBING SYSTEM OF A TOILET AND BATH

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CHAPTER 2: PROPERTIES OF WATER

GENERAL

Water plays an important part in the plumbing system. It is a common, but in many ways, an unusual liquid. Large quantities of water are required in buildings for personal use, food preparation, cleaning and general domestic purposes, and possibly also for fire fighting, laundries, swimming pools, irrigation and recreational use.

We sometimes tend to think of water as an inexhaustible natural resource. However, our supply of fresh water is definitely limited, and improved conservation practices are necessary if our needs are to be supplied.THE DEMAND OF WATER

DEMAND REQUIREMENTDrinking, Cooking, Dishwashing Must be pure, sterilized and protected from

contamination. Supplies taken direct from mains or from exclusive storage.

Personal Washing and Domestic Cleaning Similar but moderated to allow cold and hot supplies to be drawn from main storage tank or cistern via distribution network.

Laundry Generally clean and wholesome, soft and free form Iron and Manganese staining.

Fire Fighting High Pressure. Connections must not permit contamination of mains water.

Swimming Clean, filtered and sterilized with free chlorine residue for post-sterilization. Can be recirculated.

Boilers and Heating Plants Soft treated water, stored and circulated separate from domestic supplies.

Irrigation No special requirement, except reasonably free from solids and slit (result in blocked Pipes and nozzles) and uudecomposed material (pollution).

THE WATER CYCLE

The cycle basically consists of water entering the atmosphere through evaporation and returning through condensation is that these processes result in natural water purification. When water evaporates, only water molecules leave the surfaces; salts and other solids in solution remain behind. The condensed water is thus purified

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water- except in so far as it picks up pollutants in the air. Thus evaporation and condensation of water vapor are the source of all natural fresh water on earth.

Fresh water from precipitation falling on the ground gradually make its way through streams, rivers and lakes to oceans or seas as a result. As precipitation hits the ground, it may follow either of two alternative pathways, which are

A molecule of H2O can absorb a maximum capacity of 12 grains.

(Relative Humidity)RH= (4/12) x 100= 33%RH= (10/12) x 100= 83.33%

Impervious Layer- does not allow H2O to pass through.

9. Purified Water- water that undergoes a process where the pollutants are removed or rendered harmless.10. Polluted Water- water that contains one or more impurities that make the water unsuitable for a desired use.

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11. Gray Water- water drained from lavatories, sink, laundry trays and showers; contains minor pollutants.12. Black Water- water drained from water closets and urinals; carries body wastes and contains major pollutants.13. Storm Water- rainwater drained from roof gutters and downspouts.

WATER QUALITY PROBLEMS AND THEIR CORRECTION

PROBLEM CAUSE EFFECT CORRECTION1. Acidity Contains carbon

dioxide. Cistern and pond waters containing decaying vegetation are likely to be acidic

Corrosion of non-ferrous pipes, rusting and clogging of steel pipes.

Passing the water through a bed of crushed marble or limestone to achieve alkalinity, or adding sodium silicate.

2. Hardness Presence of Magnesium and Calcium

Clogging of pipes. Impaired laundering and food preparation.

Introduction of water softeners made up of Zeolite (a greenish granular material)

3. Turbidity Silt or suspended matters picked up in surface or near surface flow.

Discoloration and bad taste.

Filtration

4. Color Presence of Iron and Manganese

Discoloration of fixtures and Laundry

Precipitation by filtration through manganese zeolite (oxidizing filter)

5. Pollution Contamination by organic matter or sewage

Disease Chlorination

WATER PURIFICATION

Water purification is any method that will remove one or more materials that make the water unsuitable for a given use. The methods that are commonly used in water purification are:

1. Settling or Sedimentation2. Filtration3. Adsorption/ Flocculation-Coagulation4. Aeration5. Distillation

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6. Disinfection/ Chlorination

The natural water includes all of these purification methods except disinfection. Sitting in lakes, ponds, or the oceans, water is subject to settling (sedimentation). As it percolates through soil or porous rocks, it is filtered (filtration). Soil and humus are also good chemical adsorbents (coagulation/ flocculation). As water flows down streams and rivers, detritus is removed by biological oxidation (aeration). As water evaporates and condenses, it is distilled (distillation).

Thus, numerous freshwater sources might be safe to drink were it no for human pollution. The most serious threat to human health is contamination with disease-causing organisms and parasites, which come from the excrements of humans and their domestic animals. In human settlements, one can see how the organisms may get into water and be passed onto people before any of the natural purification processes can work.THE METROPOLITAN CEBU WATER DISTRICT (MCWD)

The Metropolitan Cebu Water District (MCWD) is the sole commercial provider in Metro Cebu comprising of four cities and four municipalities. As of year 2000, MCWD served 40% of the total population of Metro Cebu.

MCWD is primarily tasked to deliver adequate, safe, potable and affordable water to is conssionares.

MCWD has two sources or its water supply:

1. Ground Water 2. Surface Water

GROUND WATER TREATMENT PRECESS USED BY MCWD

Ground water sources are naturally and presumably purified by a compact thick filter media layer of ungraded sands, soils and rocks at considerable depth. Hence, disinfection using Chlorine Gas and other Chlorine Salts is the only treatment process employed. Here, water that is extracted from their ground through a pumping equipment is allowed to pass through chlorination facility using chlorine gas to kill any presence of coliform organisms and other froms of bacteria. Water is the stored in a reservoir ready for distribution into each concessionaire’s faucet.

At certain areas in the distribution network, Direct feed pumping stations are employed to augment the water supply. These are strategically located in different areas Metro Cebu.

SURFACE WATER BASIC TREATMENT PROCESS EMPLOYED BY MCWD

Runoff or surface water is first stored in dam. From this, water goes through a series of treatment processes.

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The Buhisan Dam (Tisa Filtration)

Buhisan Dam is Cebu’s first and only dam MCWD’s only surface water source. It supplies the Tisa (Labangon) filter plant with up to 600 cubic meter per hour (600,000 liters per hour or 158,400 gallons per hour) or about an average of 4,000 cubic meter daily (4 million liters or 1.05 million gallons).

This dam is located in Buhisan, a southern mountain baranggay of Cebu City. This was designed by 27 year-old Eusebius Julius Halsema. AG and P, the winning bider, asked Php 463, 628.00 to do the work. On November 10, 1911, the dam was completed and ready to be filled.

With a height of 27 meters, the concrete dam has a conical arch design which transfers the stress in the reservoir (caused by water strain) to the sides of the dam thereby anchoring it firmly in place.

Three 4.5 meter wide flood gates exist for flood control purposes. Its long concrete spillway allows overflow water to escape safely when the dam gates are raised.

Two kilometers of raw water main pipes extend from the dam to the distribution reservoir in Tisa. From the latter, a four kilometer pipeline distributes water to concessionaires in Cebu City. Another 21 kilometers of pipelines were also laid for improved water distribution.

Today the almost 100 year old Buhisan Dam is as strong as when it first operated.

TREATMENT PROCESS

MCWD treats the surface water using the conventional process comprising of the following:

1. Aeration2. Coagulation- Flocculation3. Sedimentation4. Filtration5. Disinfection/ Chlorination

1. Aeration- Water is sprayed into the air to release any trapped gases and absorb additional oxygen for better taste.

2. Coagulation- Flocculation- This is the process by which small sediment particles which do not settle well combine together to form larger particles which can be

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removed by sedimentation. This process includes physical and chemical process:

a. Coagulation- is the chemical process in which the coagulant reacts with the sediment to make it capable of combining into larger particles. This is called destabilization.

b. Flocculation- is the physical process in which the sediment particles collide with each other and stick together.

3. Sedimentation- This is the process by which suspended solids are removed from the water by gravity settling and deposition. This process usually follows coagulation-flocculation. The objective of this process is to remove most of the suspended solids, reducing the loads on the filters.

4. Filtration- This is the passage of fluid through a porous medium suspended matter which did not settle by gravity. In water purification, matter to be removed includes suspended silt, clay, colloids, and microorganisms including algae, bacteria, and viruses. A filter bed consists of a granular non-porous material held one place by the force of gravity or by the direction of flow.

5. Disinfection/ Chlorination- This is the most important process used in the production of water of a safe and sanitary quality. Chlorination is the method of introducing a controlled amount of chlorine to the water in order to attain a desired degree of disinfection.

After the processes, water is stored in a reservoir, then to the transmission mains, then to the, distribution lines, down to the service connections and lastly to the concessionaire’s faucet.

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SURFACE WATER SUPPLY AND TREATMENT SYSTEM

Water is taken from the water shed reservoir and piped to the treatment plant. At the plant, (1) water is aerated to release trapped gases and to absorb oxygen for better taste, (2) Alum/tawas (aluminum sulfate) is added to coagulate organic particles, and (3) the water is put into a settling basin for several hours to allow coagulated particles to settle. It is then (4) filtered through sand filters, (5) Chlorine is added to kill bacteria and put into a storage tank for distribution to concessionaires.

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CHAPTER 3: PLUMBING FIXTURES

FIXTURES- receptacles attached to a plumbing system other than a trap in which water or waste may be collected or retained for ultimate discharge into the plumbing system.

COMMON TYPES OF PLUMBING FIXTURES USED IN RESIDENCES

1. Water closet 4. Urinal2. Lavatory 5. Bidet3. Kitchen sink 6. Bath tub

WATER CLOSET- A plumbing fixture used to receive human excremental and to discharge it through a waste pipe, using water as a conveying medium. Water closets are classified according to design, make, flushing mechanism, shape and installation.

A. TYPES OF WATER CLOSET AS TO DESIGN

1. Siphon washdown 3. Siphon Vortex2. Siphon jet 4. Reverse trap

1. SIPHON WASHDOWN- The least expensive but the noisiest; only small amount of standing water- susceptible to fouling, staining and contamination. It is mechanically satisfactory and is lower in price. Hence, it is widely used and entirely acceptable where price is the main consideration.

2. SIPHON JET- The jet being submerged introduces its water underwater so that its operation is entirely muffled. It has a large amount of standing water to prevent fouling. It is mechanically efficient but expensive.

3. SIPHON VORTEX- this type of bowl develops its flushing action through the water entering through diagonal holes around the rim which creates a swirling action which forms a vortex in the center. It is considered to be the most quiet, most efficient and most sanitary water closet.

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4. REVERSE TRAP – the trap way located at the rear of the water closet eliminated the buldge at the front. The design and appearance of the bowl plus its large water area and quietness in operation, make it desirable than siphon wash down.

B. TYPES OF WATER CLOSET AS TO MAKE

1. One-piece 3. Pail Flush2. Close Coupled 4. Squat bowl

1. ONE-PIECE WATER CLOSET- The water closet fixture is manufactured with the bowl and the flush tank molded into a single unit. Usually used in tandem with the bidet.

2. CLOSED COUPLED WATER CLOSET- a water closet where in the flush tank is separate but is attached to the toilet bowl. It is a two-piece model.

3. PAIL FLUSH WATER CLOSET- a water closet comprising only of a bowl without a flush tank. Flushing action is obtained only through water poured from a pail or bucket. This is used in areas where running water systems are not available.

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4. SQUAT BOWL WATER- A water closet that is otherwise known as “Eastern type” since the user assumes a squatting position rather than a sitting position.

C. TYPES OF WATER CLOSET AS TO FLUSING MECHANISM

1. Flush tank2. Flush Valve (flushometer)

1. FLUSH TANK- holds a supply of water for flushing a fixture such as the water closet. It has a capacity of 5 to 6 gallons.

2. FLUSH VALVE- valve designed to supply a fixed quantity of water for flushing purposes. It is activated by direct water pressure without the use of a flush tank. It is also known as Flushometer or Flushometer valve. The flush valve requires 10 to 20 psi flow pressure.

D. TYPES OF WATER CLOSET AS TO SHAPE

1. Round Front

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2. Elongated Front

1. ROUND FRONT- intended for installation on a limited space.

2. ELONGETED FRONT- is more comfortable but occupies a larger space.

E. TYPES OF WATER CLOSET AS TO INSTALLATION

1. Free Standing (Flour mounted)

2. Wall Hung (Wall Mounted)

MINIMUM WATER CLOSET CLEARANCES

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ROUGHING-IN DIMENSIONS OF WATER CLOSET

PLUMBING FIXTURE MATERIALS (GENERAL REQUIREMENTS)

QUALITY OF FIXTURES

i. Denseii. Durableiii. Non-absorbentiv. Smooth, Impervious Surfacev. Free form unnecessary concealed fouling surfaces

MINIMUM TRAP DIAMETER AND DFU VALUE

i. Water closet private installation 76mm Φ (3 “) 4 DFU, 4” Φii. Water closet public installation 76mmv Φ (3”) 6 DFU, 4” Φ

*use 6 DFU when computing for septic tank size

SIZE OF WATER SUPPLY AND WSFU VALUE

i. Water closet, Flush tank 12 mm Φ (1/2 “) 3 (Private)

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5 (Public)ii. Water closet, Flush Valve 25mm Φ (1”) 6 (Private)

10 (Public)

MINIMUM SIZE OF VENT

i. The minimum size of vent for water closet is 51mm Φ.

VENTILATION OF T &B

i. Ceiling mount exhaust fan duct type.ii. Thermal exhaust fan

TILES IN TERMS OF DESIGN FOR T&B

i. 200mm x 200mm for ceramic

LAVATORY- a fixture designed for the washing of the hands or face. It is also known as wash basin.

TYPES OF LAVATORY

1. Wall Hung lavatory

2. Pedestal Lavatory

3. Counter Type Lavatorya. Over Counter

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b. Under counter

4. One- Piece Lavatory

TYPES OF LAVATORY FAUCET

a. Center Setb. Wide Spread

ROUGHING-IN OF LAVATORY

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MINIMUM LAVATORY CLEARANCE

MATERIALS FOR LAVATORIES

a. Vitreous Chinab. Enameled Cast Ironc. Stainless Steeld. Plastic

MINIMUM TRAP DIAMETER & DFU VALUE

o Wash basin, in sets 38mmΦ 2 DFUo Wash basin, single 38mm Φ 1 DFU

SIZE OF WATER SUPPLY PIPE & WSFU VALUE

o Lavatory 12mmΦ (1/2”) 1 (Private use) 2(Public use)

MINIMUM SIZE OF VENT FOR LAVATORY

o The minimum size of vent for a lavatory is 32mmΦ.

BIDET- a plumbing fixture used for washing the middle part of the body, especially the genitals. It is also known as the Sitz Bath.

- Setting and clearance for bidet shall be the same as in the water closet.- Bidet minimum trap diameter is 38mm and its DFU value is 2.

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- Size of water supply is 12mm and WSFU is 2 (private) or 4 (public)

BATH TUB- a tube for bathing, usually a fixed plumbing installation designed for one person. It is available in left outlet and right outlet.

*minimum size of vent is 38mmΦ (1 ½”)*bathtub minimum trap diameter is 38mm and the DFU value is 2.*size of supply pipe is 12mm and WSFU value is 2 (private) and 4 (public).

*REQUIREMENTS FOR WHIRLPOOL BATHTUBS (SEC. 411 NPC 1999)

a. Provide removable access panel to the pump.b. Locate the circulation pump above the crown weir of the trap.c. The pump and the circulation piping shall be self-draining to minimize water

retention.d. Suction fittings on whirlpool bathtubs shall comply with the listed standards.

URINAL- A sanitary fixture equipped with a water supply and drain for flushing away urine.

TYPES OF URINAL1. Wall hung Urinal

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2. Pedestal Urinal

3. Stall Urinal

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4. Trough Urinal

MINIMUM CLEARANCES FOR URINALS

MINIMUM TRAP DIAMETER AND DFU VALUEa. Urinal, Wall-mounted 51mm (2”) 6 DFUb. Urinal, Stall 51mm (2”) 6 DFUc. Urinal, Trap arm 51mm (2”) 3 DFU

SIZE OF SUPPLY PIPE AND WSFU VALUEa. Urinal, Wall-mounted 19mm (3/4”) 5 WSFUb. Urinal, Stall 19mm (3/4”) 5 WSFU

MINIMUM SIZE OF VENTa. The minimum size of vent is 38mmΦ

SINKS

MINIMUM TRAP DIAMETER AND DFU VALUE

Kitchen Sink (Residential); 1 ½ “Φ 38 mm Φ 2 DFU51mm minimum waste pipe

Bar Sink (Commercial) 1 ½ “Φ 38 mm Φ 2 DFU51mm minimum waste pipe

Bar Sink (Private) 1 ½ “Φ 38 mm Φ 1 DFU

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38mm minimum waste pipe Sink (Commercial, Industrial, Institutional) 1 ½ “Φ 38 mm Φ 3 DFU

58mm minimum waste pipe Sink (Clinic); Flushing Rim 3 “Φ 76mm Φ 6 DFU Service sink (Slop) 2 “Φ 51 mm Φ 3DFU Laundry Tub 1 ½ “Φ 38 mm Φ 2 DFU

SIZE OF SUPPLY PIPE AND WSFU VALUE

Kitchen sink ½ “Φ 38 mm Φ 2 (Private); 4 (Public) Scullery sink 3/4 “Φ 38 mm Φ 2 (Private); 4 (Public) Slop Sink ½ “Φ 38 mm Φ 2 (Private); 10 (Public) Laundry Tub ½ “Φ 38 mm Φ 2 (Private); 4 (Public) Bar sink ½ “Φ 38 mm Φ 1 (Private); 2 (Public)

DRINKING FOUNTAIN

Minimum trap diameter is 31mm and DFU value is 1. Size of waste supply is 12mm Φ and the WSFU value (each faucet) is 1 (private

use) or 2 (public use). Minimum size of vent is 32mm Φ (1 ¼”)

SHOWER BATH

Minimum trap diameter is 51mm and the DFU value is 2. Size of water supply is 12mm Φ and the WSFU value (each head) is 2 (private

use) or 4 (public use). Minimum size of vent is 38mm Φ.

FLOOR DRAINS

Minimum trap diameter is 51mm and the DFU value is 2.

HOSE BIBB

Size of water supply is 12mm Φ and the WSFU value is 3 (private use) or 5 (public use)

KITCHEN SINK- a plumbing fixtures usually consisting of a basin with a water supply, connected with a drain.

TYPES OF KITCHEN SINK

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a. Single Bowl- Single Drain

b. Double Bowl- Single Drain

c. Double Bowl- Double Drain

d. Triple Bowl

e. Corner Sink

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OTHER PLUMBING FIXTURES

SLOP SINK- A deep sink, usually set low and used by janitors for emptying pails of dirty water and mop cleaning.

DRINKING FOUNTAIN- A fixture consisting of a shallow basin, together with a water jet designed to provide potable water for human consumption.

LAUNDRY TUB- A deep wide sink or but used for washing clothes. It is also known as Laundry Tray or Set Tub.

SHOWER BATH- An apparatus for spraying water on the body, usually from above. Drain is through the shower bath floor drain.

SCRUB SINK- a plumbing fixture usually located in the operating room in a hospital to enable personnel to scrub their hands prior to a surgical procedure; the hot and cold water supply is activated by a knee-action mixing valve or by wrist or pedal control.

PLUMBING UNIT (Sec. 217.13 NPC 1999)The minimum standard quantities of plumbing fixtures that discharge waste into a

plumbing installation include;1 water meter1 water closet1 lavatory1 shower head and drain for a bathtub or shower stall1 kitchen sink1 laundry tray3 floor drains4 faucets/ hose Bibb13 Total numbers of fixtures and fittings that comprise a plumbing unit

NOTES ON SHOWER RECEPTOR (NPC 1999)

1. Each shower receptor shall be constructed to have a finished dam, curb or threshold of at least 25.4 mm lower that the outside floor.

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2. The dam or threshold shall not be less than 51mm nor more than 228mm in depth, when measured from the top of the dam or threshold to the top of the drain.

PLUMBING ACCESSORIES

1. Soap holder

2. Paper holder3. Toothbrush and tumbler holder

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4. Towel holder/ tower bar

5. Seat Cover

TYPICAL FIXTURE LAYOUT FOR TOILET AND BATH (minimum dimensions)

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TOILET FIXTURE CLEARANCES FOR DISABLED PERSONS (per BP 344 The Accessibility Law)

GRABRAIL HEIGHTS AT URINALS

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MOUNTING DIMENSIONS FOR TOILET & BATHROOM ACCESSORIES

MOUNTING DIMENSIONS OF ACCESSORIES AND FITTINGS AT SHOWER AREA

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MOUNTING DIMENSIONS OF ACCESSORIES AND FITTINGSAT BATH TUB/ SHOWER

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CHAPTER 4: DRAINAGE SYSTEM

The drainage system is composed of the piping network within a structure which conveys sewage, rainwater, or other wastes from their point of origin to a point of disposal, such as a public sewer or a private treatment facility (septic tank). This system is often known as the DWV System (Drainage, Waste and Vent). The complete drainage system is subdivided into four (4) sub-systems, as follows.

1. SOIL DRAINAGE SYSTEM- The piping that conveys the discharge of water closets or fixtures having similar functions (containing fecal matter), with or without the discharges from other fixtures.

2. WASTE DRAINAGE SYTEM or SANITARY DRAINAGE SYSTEM- The piping that receives the liquid discharge, from plumbing fixtures other than those fixtures (water closets) receiving fecal matter. This piping is free of fecal flow.

3. STORM DRAINAGE SYSTEM- The piping system that receives clear water drainage from leaders, downspouts, surface run-off, ground water, subsurface water, condensate water, cooling water or other similar discharges and conveys them to the point of disposal. All sanitary wastes must be excluded.

4. VENT SYSTEM- the piping system that receives a flow or air to or from a drainage system or to provide a circulation of air within such system to protect trap seals from siphonage or back pressure.

GENERAL REQUIREMENTS FOR A PROPERLY DESIGNED DRAINAGE SYSTEM

a. The piping must be air tight, gas tight and water tight.

b. Each plumbing fixture, except those with integral traps, shall be separately trapped by an approved type water seal trap. This is to prevent odor-laden and germ-laden to rise out of the drainage system and contaminate the surrounding air in the room.

c. Each plumbing fixture trap shall be provided with vent pipes. This is to protect the drainage system against siphonage and back pressure and to assure air circulation throughout the drainage system.

d. A cleanout, easily accessible, shall be provided for inspection or cleaning of the pipe run. The location of the cleanout shall be:

- At the upper end of every horizontal waste or soil pipe.- At every change of horizontal direction of not more than 22.5

degrees

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- Within 1.5 m (5’) inside the property line before the house sewer connection

- At every 15m (50’) to a horizontal run of a soil or waste pipe

e. All horizontal piping shall be run in practical alignment and at a uniform grade of not less than 2% or 2 cm per meter toward the point of disposal.

f. All horizontal piping shall be supported and anchored at intervals not to exceed 3 meters.

g. Vertical piping shall be secured at sufficiently close intervals to keep the pipe in alignment. Stacks shall be properly supported at their bases.

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DEFINITION FROM NPC 1999 EDITION

HOUSE / BUILDING DRAIN- part of the lowest horizontal piping of a plumbing system, which receives the discharges from the soil, waste and other drainage pipes inside of a building and conveys it to the house sewer outside of the building.

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HOUSE / BUILDING SEWER - extends from the house drain at a point 0.60 meters from the outside face of the foundation wall of a building to the junction with the street sewer or to any point of discharge, and conveying the drainage of one building site. No house/building sewer shall be smaller than 150mm in diameter, nor less in size than the house/building drain

WASTE PIPE - conveys only wastewater or liquid waste free of fecal matter.

SOIL PIPE- any pipe which conveys the discharge of water closet, urinal or fixtures having similar functions, with or without the discharges from other fixtures to the building drain or building sewer.

SOIL STACK PIPE- a vertical soil pipe conveying fecal matter and waste water.

VENT PIPE - used for ensuring the circulation of air in a plumbing system and for relieving the negative pressure exerted on trap seals.

VENT STACK- the vertical vent pipe installed primarily for providing circulation of air to and from any part of the soil, waste of the drainage system.

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 the clarified liquids to discharge for final disposal.

PRIVATE SEWAGE DISPOSAL SYSTEM- a septic tank with the effluent discharging into a subsurface disposal field, seepage pits or of such other facilities or may be permitted by the plumbing code.

ROOF GUTTER- the water collector at the eaves of the building.

DOWN SPOUT- A vertical pipe which conveys rain water, also known as conductor or rain water.

STORM DRAIN- Receives storm water , clear, rain or surface-water waste (SD)

CATCH BASIN- A receptacle in which liquids are retained for a sufficient period of time to allow materials to settle to deposit.

TRAP- A fitting or device designed and constructed to provide, when properly vented, a liquid seal which prevents the backflow of foul air or methane gas without materially affecting the flow of sewage or waste water through it.

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MATERIALS USED FOR THE PLUMBING DRAINAGE SYSTEM APPROVED BY THE 1999 NATIONAL PLUMBING CODE.

EXCRETA DRAINAGE PIPING

1. Cast iron2. Ductile iron3. Galvanized steel (shall not be used underground. Kept at least 152mm above

ground)4. Galvanized wrought iron (shall not be used underground. Kept at least 152mm

above ground)5. Lead 6. Copper7. Brass8. Series 1000, pvc, dmv9. Extra strength vitrified clay pipe (shall not be used above ground. At least 300mm

below finish ground level.)10.Approved material having smooth and uniform bore

NOTE: ABS and PVC DWV can be used in high rise buildings at the discretion of the RMP and with the full consent of the owner.

DRAINAGE FITTING

1. Cast Iron2. Malleable3. Lead4. Brass5. Copper6. ABS7. PVC8. Vitrified clay

VENT PIPES

1. Cast iron2. Ductile cast iron3. Galvanized steel4. Galvanized wrought iron5. Lead6. Copper7. Brass8. Schedule 40, ABS, DWV9. Series 1000, PVC, DWV

VENT STACKS

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1. Copper 2. Cast iron3. Galvanized wrought iron4. PVC

VENT FITTINGS

1. Cast Iron2. Galvanized malleable iron3. Galvanized steel4. Lead5. Copper6. Brass7. ABS8. PVC

DOWN SPOUT (INTERIOR)

1. Cast iron2. Galvanized steel3. Iron4. Brass5. Copper6. Lead7. Sched 40, ABS, DMV8. Series 1000, PVC, DWV

DOWNSPOUT (MEDIUM HEIGHT BUILDING)

1. G.I. pipe, sch. 302. CISP, S.W.3. Copper tube, type DWV4. Sch. 40, ABS, DWV5. Series 1000, PVC, DWV

DOWN SPOUT (EXTERIOR/ LOW HT. BLDG)

1. 26 GA, Galvanized sheet metal with steel pipe or cast iron at its lowest section draining to the catch basin.

DOWN SPOUT (HIGH RISE)

1. Shall be of stronger pipe materials to resist the high hydrostatic pressure.

ROOF DRAIN

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1. Cast iron2. Copper3. Other corrosion resistant materials

TRAPS (SEC. 1003 NPC 1999)1. ABS2. Cast brass3. Cast iron 4. Lead5. PVC

Figure 2- The function of the trap and one of the several functions of a vent preventing siphonage.

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LOSS OF TRAP SEAL- This failure can be attributed directly to inadequate ventilation of the trap and the subsequent minus and plus pressures which occur in the piping system. See figure 3.

Five (5) Cause of Trap Seal Loss

1. Siphonage- The withdrawal of a liquid from a trap due to a suction caused by liquid flow in a pipe.

a. Direct Self- siphonage

b. Indirect or Momentum Siphonage

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2. Back Pressure- pressure developed in opposition to the flow of liquid in a pipe due to friction, gravity or some other restriction to flow of the conveyed fluid. Excessive pressure at the lowest branch causing trap seal to look for opening.

3. Evaporation- Occurs when a fixture is not used for a long time. A Deep seal is the best solution but clogs the pipe due to accumulated solid wastes.

4. Capillary Attraction- foreign objects in the traps absorbing trap seal

5. Wind Effects- strong winds through the vent system forcing water out of the trap

SUPPORTS- are devices for holding and securing pipes and fixtures to walls, ceiling, floors or structural members. Supports include hangers, anchors, brackets, and cradles.

INDIRECT WASTE PIPING (Section 810 NPC 1999)

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The drains of the following equipments shall not be directly connected to any soil, waste and vent pipes.

1. Evaporative cooler2. Air Washer3. Air Conditioner4. Cold Storage Room5. Refrigerator6. Cooling Counter7. Food and Drinks Storage8. Culinary/ Dishwashing Sink for food preparation Room

Cooling and air conditioning equipments may be separated by an *airbreak. Food equipments shall be separated from the drainage system by a full *airgap.

*Airbreak- a physical separation, which may be a low inlet into the indirect waste receptor from the fixture, appliance or device indirectly connected, at least 25mm.

*Airgap, drainage.- the unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe, plumbing fixture, appliance or appurtenance conveying waste to the flood level rim of the receptor.

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DRAINAGE, WASTE AND VENT (DWV) PIPING SYSTEM

The drainage system is composed of groups of pipes and fittings that convey waste from the building to the proper means of disposal system.

1. Building Sewer- That part of the horizontal piping of a drainage system which system which extends from the end of the building and which receives the discharge of the building drain and conveys it to the public sewer, private sewer, individual sewage disposal system or other point of disposal.

2. Building drain- the part of the lowest horizontal piping of a plumbing system which receives the discharge from soil, waste and other drainage pipes inside of a building and conveys it to the house sewer.

3. Sewage Disposal System. A system for the treatment and disposal of domestic sewage by means of a septic tank, cesspool, or mechanical treatment, all designed to serve a single establishment, development or building.

The drainage piping system contains fittings that serve as drains, traps and vents.

Drains- fittings used for draining fluid from point of use to the piping system.

Traps- fittings or device designed and constructed to provide a liquid seal which prevent the back passage of air without materially affecting the flow of sewage or water through it.Vents-pipes and fittings installed in the system to provide air circulation so as to protect trap seals from siphonage and back pressure.

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TYPES OF TRAP COMMONLY USED IN RESIDENTIAL FIXTURES

1. P- Trap used at lavatories, sinks, floor drain and scuppers.2. Drum Trap used at bathtubs and bidets3. House Trap4. Other Appliances

a. Back flow valveb. Flow control valvec. Grease trap/ grease interceptor

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Drum Trap- A cylindrical trap commonly used on the drain pipe from a bathtub or under the bathroom floor.

Back Flow Valve- Device that prevents the reversal of flow which might flood and cause damage to the building.

House Trap- a device installed to prevent circulation of air between the drainage of the building and the building sewer.

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SIZESS AND CAPACITIES OF GREASE TRAPS

SIZES DIMENSIONS (mm)

L x W x H

PIPE SIZE INLET AND OUTLET

(mmФ)

FLOW RATE

GPM LPS

- 279 Ф x 216 51 2 0.13- 301Ф x 203 51 3 0.19- 330Ф x 241 51 4 0.25- 356 x 279 51 5 0.32

100 381 x 305 x 283 51 7 0.44200 406 x 356 x 298 51 10 0.63300 470 x 400 x 302 51 15 0.95400 629 x 495 x 381 51 20 1.26500 699 x 429 x 441 76 25 1.8600 762 x 470 x 470 76 35 2.21700 832 x 502 x 518 76 50-55 3.15800 873 x 559 x 584 76 75 4.73900 902 x 724 x 890 76 95 6.001000 1083 x 851 x 953 76 100 6.311100 1248 x 1016 x

100676 125 7.89

1200 1422 x 1054 x 1029

102 150 9.46

1300 1549 x 1105 x 1156

102 200 12.62

1400 1800 x 1308 x 1270

102-127 250 15.77

1500 2029 x 1486 x 1416

127-152 300 18.93

Note: Minimum height of 89mm required from cover of grease trap to bottom of fixtures served.

Source: Metma Trading and Industrial corporationCAT. No. 1005POT. No. 24187

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FLOW CONTROL VALVE IS RECOMMENDED FOR INSTALLATION BEWEEN FREE LEVEL HANDLE DRAIN AND GREASE TRAP TO PREVENT FATS FROM CLOGGING INTO PIPES.

FREE LEVEL HANDLE DRAIN(METMA BRAND)

USING FREE LEVEL HANDLE DRAIN IS FOR EASY DRIPPING OF WASTE WATER FROM KITCHEN SINK.

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GREASE TRAP/ GREASE INTERCEPTOR

NOTE: Grease trap is not required for individual dwelling units or for any private living quarters. (sec. 1011.1, NPC 1999): No food waste disposal unit shall be connected to or discharged into any grease trap. (Sec 1013, NPC 1999)

SIZING OF GRESE INTERCEPTORS (TABLE 10-4, NPC 1999)

C= M x W x R x F

GREASE TRAP. A DEVICE FOR REMOVING FAT AND GREASE FROM WASTE WATER BY ALLOWING THE RETAINED LIQUID TO COOL AND THE GREASE TO SOLIDIFY; THEN THE GREASE IS SEPARATED BY FLOATATION; IT RISES TO THE TOP OF THE TRAP, WHERE IT IS HELD. THE PRIME PURPOSE OF A GREASE TRAP IS TO ASSURE A FREE FLOWING DRAINAGE THROUGH PIPE LINES AT ALL TIMES BY INTERCEPTING, ACCUMULATING AND RECOVERING GLOBULES OF GREASE FAT AND OILS FROM WASTE WATER.

NOTE:1 Cubic meter= 264 gallons

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WHERE:

C= size of grease interceptors (liquid capacity)

M= Number of meals served at peak hour

R= Waste flow rate; With dishwashing machine 6 gallon flow (per meal/ day) Without dishwashing machine 5 gallon flow (per meal/ day) Single service kitchen 2 gallon flow (per meal/ day) Food waste disposer 1 gallon flow (per meal/ day) Hospital kitchen 25 gallon / bed / day

F= Storage Factors Fully equipped commercial kitchen

8 hour operation: 118 hour operation: 224 hour operation: 3

Single service kitchen: 1.5

SAMPLE PROBLEM;

Determine the capacity and volume of the grease trap for a canteen that serves an average of 50 meals a day that is open from 11:00 am to 7:00pm.

SOLUTION: S= M x W x R x F = 50 x 5 x 2.5 x 1

S= ? = 625 gallonsM= 50 mealsW=5 cal/ meal/ dayR= 2.5 hoursF= 1

Solve for volume of grease trap (V) m3 (cubic meter)

V= 625/ 264 = 2.37 cubic meter volume of grease trap

OTHER METHODS USED FOR SIZING THE GREASE INTERCEPTOR

For grease traps the serve non-scheduled meals to a nonspecific number of occupants, as in restaurants, fast foods services and luncheonettes;

C = 0.09 (K x N x H x G x S)

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Where:

C= Liquid capacityK= Facility access coefficient = 1.25 for freeways = 1.00 for recreation areas = 0.80 for main highways = 0.5 for lesser roadsN= number of seats (use fractional value if occupancy is rarely full)H= Number of hours per day of operationG= Waste flow rate (general value is 4.5 Gals)S= Sewage capacity factor = 1.7 for outflow to public sewer = 2.5 for outflow to opposite disposal

For grease traps that serve scheduled meals to a specific number of occupants as in hospitals , nursing homes and schools;

C= 0.14 (M x G x S)

Where;

M= number of scheduled meals served per day; 1, 2 or 3

TYPES OF VENTS

1. Main soil and waste vent2. Main vent3. Individual vent or back vent4. Unit vent5. Circuit vent or loop vent6. Relief vent7. Yoke vent8. Wet vent9. Looped vent 10. Utility vent

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Main soil and waste vent. The portion of soil stack pipe above the highest installed fixture branch extending through the roof.

Individual vent or back vent. The portion of the vent pipe system which serves a single fixture.

Main vent. The principal portion of the vent pipe system to which vent braches may be connected. It serves as a collecting vent line.

Unit vent. The portion of the vent pipe system which ventilates two fixture of similar design installed on opposite sides of a partition.

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The vent stack is installed between the 2nd and 3rd fixture as a precaution. In the case the soil branch becomes clogged, the 3rd fixture scours the pipe of fecal waste which may obstruct the vent.

Circuit vent or loop vent. The portion of the drainage system which ventilates two or more fixture traps that discharge into a soil or waste branch.

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Looped vent. A method of ventilation used in fixtures which are located in the room away from partitions.

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Utility vent. This is used for basement or underground public restroom wherein a vent stack may not be possible to extend 3 meters above the ground, as it may constitute a hazard and is unsightly.

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Local Vent. A pipe used to convey foul odors from a fixture or room. It has no connection with drainage piping system.

SIZE AND LENGTH OF THE MAIN VENTS

Diameter of soil and

waste stack (mm)

Number of DFUs

to be connected

MAXIMUM PERMISSIBLE DEVELOPED LENGTH OF VENT (m)

DIAMETER OF VENT (mm)

38 51 64 76 102 127 152 203

38 8 46

51 12 23 95

51 24 21 91

64 42 11 43 137

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76 30 6 24 79 198

76 60 5 23 73 183

102 100 11 30 79 335

102 250 9 29 73 305

102 500 7 21 55 229

127 550 8 21 98 305

127 1100 6 15 73 229

152 950 6 29 73 305

152 1900 5 21 55 229

203 1800 9 24 107 335

203 3600 7 18 76 245

254 2800 9 24 107

254 5600 7 18 76

SIZE OF INDIVIDUAL, BRANCH, CIRCUIT AND STACK VENTS

FIXTURE MINIMUM SIZE OF VENT (mm)/

“ФLAVATORY 32 -1 ¼ “ Ф

DRINKING FOUNTAIN

32 -1 ¼ “ Ф

SINK 38 -1 ½ “Ф

SHOWER 38- 1 ½ “Ф

BATHTUB 38 -1 ½ “Ф

LAUNDRY TUB 38- 1 ½ “Ф

SLOP SINK 38- 1 ½ “Ф

WATER CLOSET 51- 2 “Ф

URINAL 32- 1 ¼ “ Ф

SIZE OF PIPE FROM THE FIXTURE TO THE VENT (Ф)

MAXIMUM DISTANCE FROM THE FIXTURE TRAP OF THE VENT

SIZE OF THE FIXTURE DRAIN (mm)

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762 mm (2’ 6”) 32- 1 ¼ “ Ф

1067 mm (3’6”) 38- 1 ½ “ Ф

1524 mm (5’) 52- 2 “ Ф

1829 mm (6’) 76- 3 “ Ф

3048 mm (10’) 102- 4 “ Ф

SEWAGE DISPOSAL SYSTEM

Most urban and suburban areas in our country do not have public sewage treatment plants. It is therefore necessary that sanitary wastes in every building be processed and neutralized by means of a private sewage treatment disposal unit.

The general scheme of a private treatment system is relatively simple as enumerated below:

1. The sewage is retained in a submerge, tightly enclosed tank;2. Solid wastes, known as sludge, are diverted to the bottom of the tank;3. The action of bacteria present in the tank breaks up the solids and aids in

purifying the fluid;4. An amount of sludge builds up at the bottom of the tank while other organic

matters, know as scum floats to the surface;5. An outlet pipe is provided so that the partially purified effluent will be disposed to

a proper point of disposal.

Types of Private sewage treatment system

1. Septic tank2. Septic tank and Seepage Pit3. Septic tank and tile drain field4. Septic tank and mound5. Septic tank and sand filter6. Cesspool

Septic tank. A water tight, covered receptacle designed and constructed to receive the discharge of sewage from a building sewer, separate the 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.

The septic tank is the primary purification unit and should be installed close to the surface of the soil, because correction of the effluent depends on oxidation and the

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presence of aerobic bacteria that is usually found no more than 1.50 meters below the surface.

Sizing of the Septic tank. The Philippine National Plumbing Code provides the standard sizes of septic tanks ( Section 233). This is based on the capacity (the number or persons) served by the tank.

Number of person served

Inside Dimension of the digestive chamber

Depth (m) Width (m) Length (m)

10 1.20 0.90 1.8015 1.20 1.10 2.2020 1.20 1.25 2.5025 1.20 1.40 2.8030 1.30 1.50 3.0035 1.30 1.60 3.2040 1.40 1.65 3.3045 1.40 1.75 3.5050 1.50 1.80 3.6060 1.50 1.95 3.9070 1.50 2.00 4.0080 1.60 2.20 4.4090 1.80 2.30 4.60

100 1.80 2.50 5.00

IMPORTANT NOTES ON SEPTIC TANKS

1. No septic tank shall be constructed or installed within or under a house.2. Tanks must be built water tight of concrete, stone or brick.3. Both compartments are provided with manholes and tight covers for cleaning and

necessary repairs.4. Inlets and outlets are submerged and arranged in such a way that neither sludge

nor scum be unduly disturbed.

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TABLE 4-02 CAPACITY OF SEPTIC TANK (ANNEX B, NPC 1999)

SINGLE FAMILY

DWELLING (NO. OF

BEDROOMS)

MULTI-DWELLING

UNITS/ APARTMENTS

(ONE BEDROOM

EACH)

OTHER USES:

MAXIMUM FIXTURE

UNITS (DFU)

SERVED

MAXIMUM SEPTIC TANK CAPACITY

GALLONS LITERS CUBIC METER

1 or 2 15 750 2838 2.843 20 1000 3785 3.794 2 units 25 1200 4582 4.58

5 or 6 3 33 1500 5677.5 5.684 45 2000 7570 7.575 55 2250 8516.3 8.526 60 2500 9462.5 9.467 70 2750 10408.8 10.418 80 3000 11355 11.369 90 3250 12301.3 12.30

10 100 3500 13247.5 13.25

EXTRA BEDROOM; 150 GAL (567.8 LITER) EACHEXTRA DWELLING UNITS OVER 10; 250 GAL (946.3 L) EACHEXTRA FIXTURE UNITS OVER 100; 25 GAL (94.6 L ) PER FIXTURE UNIT

*FOR LARGER OR NONRESIDENTIAL INSTALLATION IN WHICH SEWAGE FLOW RATE IS KNOWN, SIZE THE SEPTIC TANK AS FOLLOWS;

1. Flow up to 1500 GPD (5677.5 L/D): Flow x 1.5 = Septic tank capacity2. Flow over 1500 GPD (5677.5 L/D)

(Flow x 0.75) + 1125= Septic tank capacity in gallons(Flow x 0.75) + 4258= Septic tank capacity in liters

3. Inlets and outlets are arranged so as to deliver the sewage to the middle third of the tank depth. For instance, in a tank 1.20 meter deep, the inlet and outlet should be submerged 0.40 meter.

4. The vaults or chambers are vented through the sanitary tees in the outlet and inlet having top ends and screened to make the tank mosquito proof.

5. The bottom of the tank should slope (1:10) towards the center and below the manhole to facilitate cleaning.

6. Not less than 0.20 meter of air space should be left between the top of the sewage and the under part of the tank cover.

7. Additional length of 1.00 meter should be added to the vault for the filter or leaching chamber.

Septic tanks should be properly sized due to the following conditions:

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1. A septic tank of smaller capacity is impractical because some leeway must be allowed for storage of accumulated sludge and;

2. A tank of larger size is not advisable because retarded bacterial activity is liable to result.

Another way to determine the size of a septic tank is to use acceptable figures derived from the plumbing practice.

For residential installations allow 0.14 to 0.17 cubic meter of tank content per person;

For school, commercial, or industrial purposes allow 0.06 to 0.09 cubic meter of tank content per person.

Minimum width of septic tank (digestive chamber) : 0.90 meter Minimum length of septic tank (digestive chamber) : 1.50 meters Minimum depth of septic tank (digestive chamber) : 1.20 meters Maximum depth of septic tank : 1.80 meters Size of the Leaching chamber : ½ the size of the digestive chamber

EXAMPLE:

Find the size of the digestive chamber for a septic tank designed to serve 300 students.

SolutionFind volume of tank: 0.06 cu.m./ person x 300 persons = 18 cubic meters

Find dimensions of tank using the following figures as assumptions:

0.90 meter width of septic tank per 100 persons and 1.80 meters for the depth of the tank

Therefore : Volume of tank = L x W x DSolving for width: 0.90 x 300/100 = 2.70 metersSubstituting : 18 cu.m. = L x 2.7 x 1.80

: L = 18/ 4.86 : L = 3.70 meters

The size of the digestive chamber is 3.70 m length x 2.70m with x 1.80 m depth

Add the leaching chamber which is 1.85 m in length

Therefore the total size of the septic tank is 5.55 m length x 2.70 m width x 1.80 m depth

*OTHER METHODS FOR DETERMINING THE SIZE OF THE SEPTIC TANK

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1. By FIXTURE METHOD: 4 log L = log (1.65 x F)

Where:L= Length of the septic tank (in meters)F= The total fixtures units that drain into the septic tank

To solve for the width of tank, use the formula: W= 0.5L To solve for the depth of the tank, use the formula: D= 0.6 L

2. By DAILY SEWAGE FLOW (in gallons/ day/ occupant or other unit)

For flow over 1500 GPD V= (1125 + 0.75Q)/ 264

Where:V= Liquid volume ( cu.m.)Q= daily sewage flow (in gallons)

Note: see table +/- 01, showing estimated flow rates

SAMPLE PROBLEM 1 (SIZING FOR THE SEPTIC TANK)

DESIGN THE DEPTIC TANK FOR AN EIGHT STORY OFFICE BUILDING. EACH FLOOR CONTAINS THE FOLLOWING FIXTURES:

5 water closets 2 slop sinks 2 drinking fountains3 urinals 2 kitchen sinks4 lavatories 6 floor drains

Solution (using fixture method)

1. Solve for total drainage fixture unit (DFU) value

Fixture Quantity No. of Floors DFU Total

WC 5 8 6 240U 3 8 6 144

LAV 4 8 2 64SS 2 8 3 48KS 2 8 4 64FD 6 8 2 96DF 2 8 1 16

TOTAL DFU 672

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2. Solve for length of septic tank, use the formula:

4 log L= log (1.65 F)

Substituting

4 log L= log (1.65 x 672)= log 1108.8= 3.04L= log -1 (3.04/4)L= 5.75 meters

3. Solve for width of septic tank

W= 0.5 L= 0.5 (5.75)

W= 2.88 meters

4. Solve for depth of septic tank

D= 0.6 L = 0.6 (5.75)D= 3.45 metersV= L x W x DVolume = 5.75 x 2.88 x 3.45= 57.13 meters

TABLE 4-03 ESTIMATED SEWAGE FLOW RATES

OCCUPANCY GAL/DAY/ OCCUPANT OR OTHER UNITAirports 15/ employee + 4 / passengerStandard apartments 1 BR= 125, 2 BR= 250, 3 BR= 325Luxury apartments Multiply above by 1.3Lecture halls 2/ seatTheaters/ Auditoriums 3/ seatBowling alleys 75/ laneCountry clubs, health clubs, gyms 25/ lockerChurches 4/ seat; (with kitchen): 7/ seatDance halls 5/ occupantDay camp 15/ camper and staffDental offices 750/ chair/ dayFactories: (w/o shower) : (w/ shower) : (w/ cafeteria)

25/ person/ shift (excluding industrial wastes)Add 10/ employeeAdd 5/ employee

Hospitals 150/ bed

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Hotels: (w/o kitchen) 60/ bed; (with kitchen)- 70/ bedLaundromats 50/ wash cycle or 400/ machine/ dayNursing homes 125/ bedMotels 50/ bed; (with kitchen)- 60/ bedOffices 15/ employee or 1.12/ sq. m. floor areaPicnic areas with flush toilets 50/ carResidences 1 BR= 150, 2 BR= 330, 3 BR= 400, 4 BR=

475, 5 BR= 550Luxury= multiply above by 1.2

Restaurants/ cafeterias 15/ occupant/ mealCocktail lounge 20/ occupantRooming houses 40/ guestSchools Elementary: 15/ student

Intermediate/ high school: 20/ studentWith gym and showers: add 15/ lockerWith cafeteria: add 3/ studentAdm. Staff and office: 20/ employee

Service station 900 for 1st bay; add 500/ add’l bayShopping malls 15/ employeeStores 20/ employee; w/ public c.r. 1.2/ sq. m

(sales area)Swimming pools: private or public 10/ swimmer and staffTrailer parks, tourist camps 35 (with central bath house)

50 (with built-in baths)

NOTE: to convert from gallon to liter, multiple value by 3.785

Source: architectural engineering design: mechanical systems; Robert brown butler; Mcgrow-hill 2002.

SAMPLE PROBLE 2 (SIZING OF SEPTIC TANK)

Design the septic tank for an eight storey office building that will house 1200 employees (representing 30% of the total employee population)

Solution (By sewage flow method)

Use formula: V= ((1125 + 0.75Q)/ 264)) x (GPD), V= ((4258 + 0.75Q)/ 1000) x (LPD)

Solving for Q:Q= 1200 x 15 GPDQ= 18000 gallons/ person/ day

GDP is from table 4-01; for office, sewage flow is gallons/ person/ day.

Substituting:

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V= (1125 + 0.75 (18000)) / 264 = (1125 + 13500)/ 264V= 55.40 cubic meter

Solving for length and width, for depth use 1.80m.

Area= 55.40 m3 / 1.80 m = 31m2

For Length: (try 4m as width)\

L= 31m2/ 4m = 7.75m

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GARAGE INTERCEPTOR Sizing of garage interceptor (for sand, silt, grit and oil)

C = V x W x R x F

Where:

C= Capacity of garage interceptorV= Number of vehicles served per hourW= Waste Flow Rate (check with equipment manucfacturer)R= Retention time (Use General Value of 2 hours)F= storage factor = 1.5 for self serve (general) = 2.0 for employee operated

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LAUNDRY INTERCEPTOR Sizing of laundry interceptor (for silt, lint and grease)

C= N x W x R x F x H

Where:

C= capacity of laundry interceptorN= number of washing machinesW= waste flow rate

Hospital laundry 40 gal/ bed/ day Hotel Laundry 60 gal/bed/ day Self-service laundry 50 gal/ bed/ day

(minimum; 10 hours/ day)

R= Retention time (use general value of 2 hours)F= Storage Factor (use general value of 1.5)H= 2 cycles/ hour

PERCOLATION TEST Percolation test determines the absorption capability of the soil at the site. This

test must be down before designing a waste water system. If the percolation rate exceeds 60 minutes, the soil not suited for a seepage pit. A

percolation rate over 30 minutes indicates border line suitability for soil absorption, and other methods of waste water disposal should be considered.

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STEPS

1. First fill the test hole with water and allow it to seep into the surrounding soil.2. Then refill the hole to a depth of at least 150mm while the bottom of the hole is

still wet.3. Measure the depth, of the water and record the time it takes for all of it to be

absorbed into the soil.4. Calculate the time required for the water level to drop 1 inch.

PRIVATE SECONDARY: TREATMENT SYSTEMS FOR SEWAGE

Individual sewage treatment systems, septic tanks are commonly used for primary treatment. Four options for secondary treatment are shown here. Tertiary treatment usually is only required for effluent discharge into waterways. (a) Seepage pits are not usually used. (b) Drainfields constitute the most commonly used options. (c, d) Mounds and sand filters are more expensive to construct and used where high water tables preclude the use of option (a) or (b).

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SEEPAGE PIT/ DRY WELL

SEEPAGE PIT. A loosely lined excavation in the ground, which receives the discharge of a septic tank and designed to permit the effluent from the septic tank to seep through the pit bottom and sides. (sec 220.6 NPC 1999)

The required size of a seepage pit can be determined from a percolation test and estimated amount of effluent from the facility. Several smaller pits for a facility may be more feasible than one large pit. However, care should be considered to ensure that there is equal distribution of the waste water to all the pits.

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TABLE 4-04 APPLICATION RATE FOR SEEPAGE PITS

Solving for required absorption area

A= E/ R

Where:

E= total estimated effluent (gal)R= Application rate ( GPD/ m2)

SIZING OF THE SEEPAGE PIT:

1. Perform the percolation test and determine the application rate from the table of values above.

2. Find the required absorption area (A) by dividing the total

estimated effluent (E) from the facility by the application rate (R).3. Find the required absorption area per wall by dividing the area by 44. Find the length of each wall by dividing the required absorption area per wall by

the depth of the pit (from 1.80m to 4.25m) the bottom of the pit must be at least 600 mm above the ground water table.

SAMPLE PROBLEM (SEEPAGE PIT)Design the seepage pit for a septic tank that serves a 3 bedroom residential

height. Data from the percolation test conducted showed that the soil percolation rate is 15 minutes and the depth of pit is 1.80 meters.

SOIL PERCOLATION

RATE (25mm) (1”)

APPLICATION RATE (GPD/ SQ. METER)

1 minute 57.00

2 minutes 46.22

5 34.40

10 24.73

15 19.35

20 16.12

30 11.83

45 8.60

60 5.34

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Solution:1. DETERMINE THE TOTAL ESTIMATE EFFLUENT.

From table 4-01 estimated flow rates for 3 bedrooms= 400 GPD :. E= 400

2. DETERMINE APPLICATION RATEFrom table of values, 15 minutes percolationRate= 19.35 GPD/ m2:. R= 19.35

3. SOLVE FOR REQUIRED ABSORPTION AREA (A)A= E/R= 400/ 19.35

A= E (estimated effluent) Gal. / R (Application rate) gal/m2 A= 20.67 square meters

4. TRY SEEPAGE PIT AS SQUARE IN PLAN.SOLVE REQUIRED ABSORPTION AREA PER WALL (W)

W= A/4 = 20.67 m2/ 4 W= 5.17 sq. m.

5. SOLVE FOR LENGTH OF WALL. USE 1.80m AS DEPTH OF PIT.L= 5.17 m2/ 1.80m L= W (absorption area/ wall) m 2

D (Depth of pit) mL= 2.87 m

OPTION 1

4. TRY CYLINDRICAL SEEPAGE PIT

W= A/ 1= 20.67m2

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5. SOLVE FOR LENGTH OF WALL. USE 1.80m AS DEPTH OF PIT.

L= 20.67 m2/ m= 11.48m

6. SOLVE FOR DIAMETER OF PIT

Ф= L / π= 11.48/ 3.1416Ф= 3.65m

METHOD NO. 2

SIZING OF SEEPAGE PIT (BY SOIL TYPE METHOD)

TABLE 4-05 LEACHING AREA DESIGN CRITERIA FOR FIVE TYPICAL SOILS (UPC 1982)

TYPE OF SOIL

REQUIRES AREA OF LEACHING

(sq. m. / 100 gal)

MAXIMUM ABSORPTION CAPACITY OF

LEACHING AREA FOR A 24 HOUR

PEROID (GAL/ M2)

MAXIMUM ALLOWABLE SIZE OF SEPTIC TANK

CUBIC METER

GALLON

Coarse sand or gravel

1.86 53.75 28.41 7500

Fine sand 2.32 43.00 28.41 7500

Sandy loam or sandy clay 3.72 26.87 18.94 5000

Clay with considerable

sand or gravel

8.37 11.82 13.26 3500

Clay with small

amount of san or gravel

11.16 8.92 11.36 3000

SAMPLE PROBLEMDesign the seepage pit for a septic tank of a 3 bedroom house. As per site

investigation, the type of soil sandy loam. The ground water table is 2.50 meter below the grade line.

Solution

1. Determine the estimated sewage flow from the table of values, a 3 bedroom house will have an estimated flow rate of 300 gal/ day.

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2. From table of values above, determine the required area of leaching (A) for the type of soil at the project site.From table: sandy loam= 3.72 m2/ 100 gal

A= 3.72 m2 x 400 gal/ day 100 galA= 14.88 m2

3. Try cylindrical seepage pit, solve for circumference. Use depth of pit= 1.80 meter.C= A = 14.88 D 1.80

C= 8.27 meters

4. Solve for diameter of pitФ= C = 8.27 m Π 3.1416

Ф= 2.63 meters

SANITARY DRAIN FIELD- Sanitary drain field is a method of sewage disposal which allows sewage to seep directly into the soil.

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Tile drain field for a four-bedroom, eight-person house. Although the drawings are not to scale, the dimensions would indicate a required area about 20 x 70 ft (6 x 21 m) on the lot. When it is considered that it is best not to have the elements run below walks, drives, or other paved areas, sewage treatment on a small lot demands considerable space. (a) Transverse and longitudinal sections. (b) Schematic plan.

TABLE 4-06 DISPOSAL FIELD TRENCHES

Part A. DimensionsMinimum Maximum

Length of drain line(s) - 100ft (30.5 m)Bottom width of trench 18 in (457.2 mm) 36 in (914.4 mm)Spacing of lines, O.C. 6ft. (1.8m) -

Depth of earth cover over lines

12 in (304.8 mm)(note: 18in (457.2 mm)

(preferred)

-

Grade of lines Level 3in. / 100ft (25mm/m)Filter material

Over drain linesUnder drain lines

2in. (50.8 mm)12 in. (304.8 mm)

--

Part B. Leaching Areas

Trench bottom: minimum 150 ft2 (14m2) per systemTrench side wall: minimum 2 ft2/ ft Maximum 6

Minimum spacing of drain lines: 4 ft (1.2m) plus 2 ft (0.6m) for each additional foot (0.3m) of depth beyond 1 ft (0.3m) below the bottom of the drain line.

MATERIALS FOR DISTRIBUTION LINES FOR SANITARY DRAIN FIELD/ LEACHING FIELD (ANNEX B 6.1., NPC 1999)

1. Clay tile with open joints2. Perforated clay pipe3. Perforated bituminous fiber pipe4. Perforated high density PE pipe5. Perforated ABS pipe6. Perforated PVC pipe

METHOD 1: SIZING OF SEPTIC TANK DRAIN FIELD (BY SEWAGE FLOW METHOD)

“Rule of thumb for septic tank drain fields sizingIn conventional units (minimum of 70m2 area for any system)

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For shallow trenches in poorly draining soil:Drain field area= total sewage flow in GPD x 0.33m2/ gal

Or = total sewage flow in LPD x 0.087 m2/ liter For deep trenches in well draining soil:

Drain field area= total sewage flow in GPD x 0.04m2/ galOr = total sewage flow in LPD x 0.01 m2/ liter

SAMPLE PROBLEMDesign the drain field for a septic tank serving 3 bedroom house, located in a

poorly draining soil. The sewage flow is 400 GPD.

Solution

1. Solving for drain field area (D)

D= 400 GPD x 0.33 m2 for poorly draining soil.D= 132 sq. m

2. Determine the cross section size of the trench and effective absorption area (E)

3. Solve for trench length (L)for trench side walls = 1.83 m2/ m+ for trench bottom = 0.90 m 2/m

= 2.73 m2/m

L= D = 132 m 2 E 2.73 m2/ m

Trench length = 48. 35m = say 50 m4. Select the number of lines for the disposal field. Try 2 lines.

:. 50m / 2 = 25 meters

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METHOD 2: SIZING OF SEPTIC TANK DRAIN FIELD (BY PERCOLATION TEST METHOD)

SOLVING FOR THE LEACHING FIELD

1) As to the length of the leaching tiles:L= 0.57 W (92 B + 7 F + 0.6 V)

WhereL= minimum length of leaching field drainage tile, metersW= Minimum width of each leaching field trench, use 0.90mB= Number of bedrooms (if any) whose household fixture units drain into the leaching field.F= Number of commercial plumbing fixture units of waste flow (if any) that drain into the leaching field.V= Volume of non fixture waste flow (if any) that drains into the leaching field.P= Percolation test result (assume 5 min/ 25mm drop, if percolation test is not available)

2) As to the area of the leaching field:

A > 1.80 L

Where:

Disposal field area:A= (1.50 + 25 + 1.50) 1.80A= 50.4 m2 < 70 m2 (rule of thumb)* Revise distance of trenchesD= 70/ 28 = 2.5 m

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A= minimum area of leaching field, sq. m.L= minimum length of drainage tile, m.

SAMPLE PROBLEM

Design and size the leaching field for the septic tank serving a 3 bedroom house if the percolation test indicates a rate of 5 minutes per 25mm drop.

Solution

1. Find the length of the leaching tiles or pipeL= 0.57 W (92 B + 7 F + 0.6 W) = 0.57 (0.90) x [92 (3) + 7 (0) + 0.6 (0)] 5 = 0.513 x (276 x 1.87)L= 264.76 meters

Say: 2652. Determine number of drainage lines (N) based on minimum length of 6m and

maximum length of 30m.

Minimum: N= 265 = 44.2 = 44 lines 6

Maximum: N= 265= 8.8 = 9 lines 30

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3. Find the area of the leaching field

A > 1.8 L = 1.8 (265) A= 477 m2

REQUIRED CONDITIONS FOR THE PROPER FUNCTIONING OF THE DRAIN FIELD

1. The ground water is well below the level of the tile field.2. The soil has satisfactory leaching characteristics within a few meters of the

surface, extending several meters below the tile.3. The subsurface drains away from the field.4. The area is adequate.5. There is no possibility of polluting potable water supplies, particularly from

shallow or driven wells in the vicinity.

Mounds with leaching beds offer an option when the water table is high. The system serves a two- or three-bedroom home.

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Relief Vent. The portion of the vent pipe installation that permits additional circulation of air around the drainage pipes to eliminate back pressure and retardation of waste flow.