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THE SEPTIC TANK ANDSEWERAGE SYSTEMSPRIVATE SEWERAGE DISPOSAL SYSTEMSDISPOSAL PHASEThe final stage of the plumbing process; where used water and water carried waste are brought to various disposal outlets.

PRIVATE SEWERAGE DISPOSAL SYSTEMSDISPOSAL PHASEIn houses connected to city sewer systems, disposal of household sewage is simple; the waste water simply flows out of the houses, and down into the city sewer pipe.However, not all houses are not connected to a city or municipal sewer, and waste from these homes must be disposed in other ways, and the most common way is with the use of Septic Tanks.Definition: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.SEPTIC TANKSPRIVATE SEWERAGE DISPOSAL SYSTEMS1. SLUDGE:Solid organic matter that are denser than water and settle at the bottom of the septic tank.2. SCUM:Lighter organic matter that rise at the surface of the water3. EFFLUENT:The liquid content of the sewage.Organic Matters Contained in a Septic TankPRIVATE SEWERAGE DISPOSAL SYSTEMS

PRIVATE SEWERAGE DISPOSAL SYSTEMSOrganic Matters Contained in a Septic TankAerobic bacteria (aerobes)These are bacteria that relies on oxygen to survive which are found on Scums inside the septic tank

Anaerobic bacteria (anaerobes)These are bacteria that can survive in places without oxygen and are found inside the sludge at the bottom of the septic tank floor.Bacteria in Septic Tank to encourage DecompositionPRIVATE SEWERAGE DISPOSAL SYSTEMSFacultative bacteriaThese are bacteria that functions with or without the presence of oxygen.

These three types of bacteria have no relation to disease. They thrive naturally and will function when conditions are favorable in terms of:Food SupplyTemperatureMoistureBacteria in Septic Tank to encourage DecompositionPRIVATE SEWERAGE DISPOSAL SYSTEMS

PRIVATE SEWERAGE DISPOSAL SYSTEMSBacteria in Septic Tank to encourage DecompositionStabilizationThe process of decomposition occurring inside the Septic TankDecomposition is caused by anaerobic bacteria referred to as putrefaction, often accompanied by bad odors.Aerobic decomposition on the other is not accompanied by unpleasant odor.Bacteria in Septic Tank to encourage DecompositionPRIVATE SEWERAGE DISPOSAL SYSTEMSSepticA sewage that turns dark and smell unpleasantly due to anaerobic decomposition.Bacteria in Septic Tank to encourage DecompositionPRIVATE SEWERAGE DISPOSAL SYSTEMSAerobic DecompositionAccomplished with no definite time and could be with no definite time and could be within a matter or hours.TYPICAL DESIGN OFSEPTIC TANKS

Typical Septic Tank Designs and LayoutPRIVATE SEWERAGE DISPOSAL SYSTEMSSINGLE CHAMBER SEPTIC TANKTypical Septic Tank Designs and LayoutPRIVATE SEWERAGE DISPOSAL SYSTEMSDOUBLE CHAMBER SEPTIC TANK

PlansShould show all dimensions, reinforcement, structural calculations, and other pertinent data needed.PRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutDESIGN CRITERIA:Quality of DesignShall be such as to produce a clarified effluent of acceptable standards and shall provide adequate space for sludge and scum accumulations.MaterialsConstructed of durable materials, not subject to excessive corrosion or decay, shall be watertight.Material: cement (usually) or pre-fabricated cast ironPRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutDESIGN CRITERIA:Conventional Septic Tanks have a minimum of two (2) compartmentsThe Digestive Chamber not less then 2/3 of the total capacity of tank and not less than 2 cum of liquid capacityThe Leeching Chamber should have a maximum capacity of 1/3 of the total capacity of the tank, with a minimum of 1 cum liquid capacityPRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutCOMPARTMENTS:Typical Septic Tank Designs and LayoutPRIVATE SEWERAGE DISPOSAL SYSTEMS

The bottom of the digestive chamber should maintain a slope of 1:10 to collect the sludge and make it easily accessible from the manhole.PRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutCOMPARTMENTS:MANHOLES: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.Typical Septic Tank Designs and LayoutPRIVATE SEWERAGE DISPOSAL SYSTEMS

PRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutAIR SPACE:Side walls should at least extend 228.6 mm above the liquid surface in order to maintain the air needed by aerobic bacteria digesting the scum.PARTITION (between compartments):An inverted fitting 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.Typical Septic Tank Designs and LayoutPRIVATE SEWERAGE DISPOSAL SYSTEMS

PRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutLENGTH AND LOCATION OF INLET & OUTLET:Inlet shall extend 101.6 mm above and at least 304.8 mm below the water surface.The invert of the inlet pipes shall be at level not less than 50.8 mm above the invert of the outlet pipe.VENT DIAMETER:Equal to the cross sectional area of the house sewer.PRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and LayoutSIZES OF PIPE INLET & OUTLETS & THEIR VERTICAL LEGS:Inlet and Outlet pipes diameter size not less than the sewer pipe.Vertical legs of inlet and outlet pipes diameter size not less than the sewer pipe nor less than 104.6 mm.

LOCATION:Should not be located underneath the house.At least 15 meters from the water distribution system.Typical Septic Tank Designs and LayoutPRIVATE SEWERAGE DISPOSAL SYSTEMS

PRIVATE SEWERAGE DISPOSAL SYSTEMSCOMBINATION PUBLIC SEWERS:The oldest variety of Sewer System.Carries both storm and sanitary wastes.STORM SEWERS:Carries only rainwater collected from the drain or from the streets.Terminates at natural drainage areas (i.e. lakes, rivers, and water reservoirs)Require manholes to serve as clean-outs and to make sewers accessible for inspection and repair.Classification of SewersPRIVATE SEWERAGE DISPOSAL SYSTEMSTypical Septic Tank Designs and Layout

PRIVATE SEWERAGE DISPOSAL SYSTEMSSANITARY SEWERS:Carries regular sanitary wastes only.Terminates in a modern sewage disposal plant for treatment.Built at a depth of 3 meters.Classification of SewersPRIVATE SEWERAGE DISPOSAL SYSTEMSTRIBUTARY SEWERS:Termination points of individual units or structures.Usually round shaped, with diameters between 0.60 to 1.2 metersMade of vitrified clay or cement pipes; often installed by the curb line, before the street.2 Types of Sanitary SewersPRIVATE SEWERAGE DISPOSAL SYSTEMSINTERCEPTING SEWERS:a.k.a. 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.Sloped at an angle of 1:50 or 2%.2 Types of Sanitary SewersPRIVATE SEWERAGE DISPOSAL SYSTEMSINTERCEPTING SEWERS:Lifting stations are placed at certain intervals and pumps or sewage ejectors are used to lift the waste; sewers terminate at the disposal plant2 Types of Sanitary Sewers

PRIVATE SEWERAGE DISPOSAL SYSTEMSThe function of Drainfield:The absorption field is frequently a network of drain lines (pipes with holes in them) that carry wastewater from the septic tank and apply it to the soil.The size of the absorption field varies from site to site, but most are small enough to fit in a backyard and cover and area between 400 and 800 ft2.DRAINFIELDSPRIVATE SEWERAGE DISPOSAL SYSTEMSDRAIN FIELDS

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