SEWAGE & STROM WATER DISPOSALWATER SUPPLY

By-:vvvvvv vvvAnshu Dadwal (Lecturer)v vvv

THE BUILDING STACKS

OFFICE BUILDING STACK

Stacks are generally large diameter CI pipes that carry wastewater collected from various locations in the buildings. There are two types of stacks, the old two stack system of two separate stacks, a pipe for wastewaters from water closets and another for all other sources, and the fully vented one stack system in which single pipe carries all wastes.They are also known as combined - and separate - system respectively. Most rainwater is conveyed directly to surface water drain in a variant called partially separate system.

SINGLE STACK SYSTEM

DOUBLE STACK SYSTEM• Also known as Two Pipe or Separate System

PARTIALLY SEPARATE SYSTEM

PARTIALLY – SEPARATE SYSTEM ACESSORIES

PARTIALLY SEPARATE SYSTEM ACESSORIES

PARTIALLY SEPARATE SYSTEM ACESSORIES

PARTIALLY SEPARATE SYSTEM ACESSORIES

THE NEGATIVE PRESSURE

Induced Siphonage. Discharge from one appliance creates a vacuum in another appliance’s branch pipe.Back Pressure. Excess pressure due to resistance at the base of a stack. large radius bends are therefore used.Self – Siphonage. Suction created as an appliance discharges into the stack.Negative pressure is created when total Bernoulli head downstream exceeds that upstream due to large pressure and/or velocity gradients.It damages the water seal of appliances and foul air enters the building.

VENT FOR DRAINAGE

VENT FOR DRAINAGE

VENT FOR DRAINAGE

SINGLE STACK DESIGNA stack coupled with a vent arrangement is needed in 3-5 storied buildings. Vents are not needed in low rise buildings. Above five stories the ground floor appliances are connected to a separate stack and vent system and others to a common system. Above twenty stories, both ground and first floor appliances are separately drained.

FULLY – VENTED SINGLE – STACK SYSTEMThe fully vented single stack system is used in

buildings where there are a large number of sanitary appliances in ranges, e.g. factories, schools, offices and hospitals.The trap on each appliances is fitted with the anti-siphon or vent pipe. Individual vent pipes combine in a common vent in a range, which is inclined until it meets the vertical vent stack. The vent stack may be left open to atmosphere or it may connect to the main stack at a point above the spillover level of the highest appliance. The bottom of vent stack is connected to the main stack close to the bottom rest bend to relieve any compression at this point. Diameter of vent = half the diameter of main stack above 100mm dia; Two third for 50mm dia.

VENT TOP DETAILS

AIR ADMITTANCE VALVE

DRAINAGE IN BASEMENTS

DRAIN SEWER CONNECTION

DRAIN SEWER CONNECTION

DOMESTIC SEWAGE DISPOSAL

DOMESTIC SEWAGE DISPOSAL

SEPTIC TANK DESIGN

No. of Users Length, m Breadth, m Liquid Depth, m 5 1.5 0.75 1.0 10 2.0 0.90 1.0 15 2.0 0.90 1.3 20 2.3 1.10 1.3 50 5.0 2.0 1.0 100 7.5 2.65 1.0 150 10.0 3.0 1.0 200 12.0 3.3 1.0 300 15.0 4.0 1.0

Free Board = 300 mm

Two compartments of 2:1 volume ratio are preferred.

MUNICIPAL SEWAGE DISPOSAL

RAIN WATER HARVESTING

THANK YOU.

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