page 55 - 79 Flashcards by ERMETANIO, RHABIE MAE T.

Minimum dimensions for Private sewage disposal systems

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

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Design Criteria

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

Plans

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shall be such as to produce a clarifies effluent of acceptable standards and shall provide adequate space for sludge and scum accumulations

Quality of Design

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

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

Materials

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have a minimum of 2 compartments

Compartments

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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

First Compartment

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Maximum capacity of 1/3 total capacity of tank; minimum of 1 cum liquid capacity

Secondary Compartment

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

TRUE

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Maintain a slope of ___ at the bottom of the digestion chamber to collect the sludge and make it easily accessible from the manhole

1:10

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With at least two 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

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Diameter size not less than the sewer pipe

Inlet and Outlet Pipes

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diamter size not less than the sewer pipe nor less than 104.6 mm

Vertical legs of inlet and outlet pipes

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

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

Length and location of inlet and outlet

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equal to the cross sectional area of the house sewer

Vent Diameter

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Side walls shall extend 228.6 mm above liquid depth

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

air space

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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 deplth of the liquid. Wooden baffles are prohibited

Partition

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

Structure

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The capacity if 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

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Should not be located underneath the house

At least 15 meters from the water distribution system

Location

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3 degrees or grades of waste water

Grey Water (or Area Water)
Black Water
Storm Water

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Waste water with the exception of human wastes

From laundries, was basins, sinks, tubs, etc.

Grey Water or Area Water

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WAter plus solid and liquid human wastes

Black water

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Rainwater only

Storm Water

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Classification of Sewers

Combination Public Sewers
Storm Sewers
Sanitary Sewers

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Oldest variety Carries both storm and sanitary wastes

Combination Public Sewers

Carries regular sanitary wastes only Terminates in a modern sewage disposal plant for treatment Built at a depth of 3 meters (tributaries)

Sanitary Sewers

Two types of Sanitary Sewers

Tributary and Intercepting Sewers

Termination points of individual units or structures Usually round shaped, with diameters between 0.60 to 1.2 meters

Tributary Sewers

Made of vitrifies clay or cement pipes, often installed by the curb line, before the street Normally laid in the Northern or Eastern side of streets with east-west or north-south orientation

Tributary Sewers

Aka collecting sewers Termination points of tributary sewers Placed much lower in the ground, from 4 to 30 meters in depth Varies in shape but have a diameter or effective opening ranging from 0.60 to 3 meters

Intercepting Sewers

Slope at an angle of 1:50 or 2% Lifting stations are placed at certain intervals and pumps or sewage ejectors are used to lift the waste, sewers terminate at the disposal plant

Intercepting Sewers

____ of all building shall be connected to the public sewer. When not available, they shall be connected to an approved private sewage disposal system

Drainage Pipes

Public sewer may be considered as not being available if it is _____ from any proposed building or exterior drainage facility

more than 61 meters

It is unlawful to discharge any ashes, cinders, solids, rags, flammable, poisonous, explosive liquids or gases, oils, grease, and other things whatsoever which would cause damage to the public sewer or private disposal system.

True

No rain, surface or subsurface waters shall discharge into any excreta drainage system

True

No cesspool and septic tank effluents, seepage pit or under drain system shall be connected to the excreta _____ leading to a public sewer main

building sewer

No commercial food waste grinder shall be connected to a private or public sewage disposal system.

True

The minimum size of any building sewer shall be determined on the basis of the total number of fixture units drained by such sewer. No building sewer shall be smaller than _____ diameter nor less in size than the building drain

150 mm

Building sewers shall be run in practical alignment at a uniform slope of __ toward the point of disposal

not less than 2% or 21 mm/m

When impractical due to depth of street sewer, structural features or to adverse arrangement of building, to obtain a slope of ____ in dia may have a slope of not less than 1% (10.5 mm/m) and those 203 mm dia and larger may have a slope of not less than 0.5% (5.3 mm/m)

2%, sewers 102 mm and 152 mm

No building sewer shall be installed _____ from the outer face of any building foundation, nor less than 0.3 M below the finish surface of the ground.

less than 0.6 M

Location of building sewer in relation to other services is shown below. _____from any building or structure

0.60m

Location of building sewer in relation to other services is shown below. _____ from water supply wells

15.2 m

Location of building sewer in relation to other services is shown below. _____from streams

15.2 m

Location of building sewer in relation to other services is shown below. _____from domestuc supply pipes

0.30m

Location of building sewer in relation to other services is shown below. _____from public water main

0.30m

Building sewer or drainage pipe of clay or materials which are not approved for use within a building shall not be laid in the same trench as water pipes unless: the bottom of the water pipe is ____ above the top of the sewer pipe (NPC 1208.1.1),

0.3 m

Building sewer or drainage pipe of clay or materials which are not approved for use within a building shall not be laid in the same trench as water pipes unless: the water pipe is placed on a solid shelf excavated at one side of the common trench with a minimum horizontal distance of at least ___ from the sewer or drain pipe

0.3 m

____ shall be installed not less than 3 meters away from sewer line in both directions.

Water pipe joint

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

Disposal Fields

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

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

Distance from Water Table

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

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

Seepage Pits

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

Capacity

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

Size of Seepage Pit

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

Cesspools

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

Temporary Permits

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

Outside Privy

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 ___ for such waste shall be installed.

interceptor

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

separate disposal system