Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Describe the function and components of various drainage systems.
• Explain the principles of gravity and pressure drainage.
• Identify common plumbing fixtures and fittings.
• Explain the importance of ventilation in plumbing systems.
• Describe common sanitation fixtures and building codes.

Lesson summary

Drainage, plumbing, and sanitation are fundamental aspects of building construction and directly impact public health, environmental sustainability, and the quality of life for all South Africans. Poor drainage can lead to flooding, structural damage to buildings, and the spread of waterborne diseases. Inadequate plumbing can result in water wastage and unsanitary conditions. Proper sanitation is essential for preventing the spread of diseases like cholera and typhoid, which unfortunately still pose a threat in some parts of our country. Understanding these systems is crucial for any aspiring Civil Technologist and plays a vital role in creating healthy and sustainable communities.

Lesson notes

2.1 Drainage Systems Drainage systems are designed to remove excess water from a building site and the building itself. There are several types of drainage systems: Stormwater Drainage: This system collects rainwater from roofs, paved areas, and other surfaces and directs it away from the building foundation to prevent flooding and water damage. Gutters, downpipes, and surface drains are common components.

Wastewater Drainage (Sanitary Drainage): This system removes wastewater from plumbing fixtures (toilets, sinks, showers, etc.) and carries it to the municipal sewer system or a septic tank. This system includes soil pipes, waste pipes, and traps.

Subsoil Drainage: This system removes groundwater from around the building foundation to prevent hydrostatic pressure buildup, which can cause structural damage. This often involves perforated pipes surrounded by gravel that collect water and direct it away from the foundation. Gravity Drainage vs.

Pressure Drainage: Gravity Drainage: This is the most common type of drainage system. It relies on gravity to move water through pipes. Pipes are sloped downwards to allow wastewater to flow freely. A minimum slope is crucial to prevent solids from settling and causing blockages.

Pressure Drainage: In situations where gravity drainage is not feasible (e.g., when wastewater needs to be pumped uphill or across a flat area), pressure drainage systems are used. These systems involve pumps that create pressure to move wastewater through pipes. These are typically used in basement bathrooms or where the sewer line is at a higher elevation.

Example 1: Calculating Minimum Pipe Slope for Gravity Drainage The minimum slope required for a 110mm diameter soil pipe is typically 1 in 40 (1:40) according to South African building regulations. This means for every 40 cm of horizontal distance, the pipe must drop 1 cm in elevation. If a section of pipe is 10 meters long, the total drop required is: 10 meters = 1000 cm (1000 cm / 40) = 25 cm Therefore, the pipe must drop 25 cm over its 10-meter length.

Example 2: Stormwater Runoff Calculation A building has a roof area of 200 square meters. The rainfall intensity during a heavy storm is 50 mm/hour. Calculate the stormwater runoff rate. Runoff Rate = (Roof Area) x (Rainfall Intensity) Runoff Rate = (200 m²) x (50 mm/hour)

Convert mm/hour to m/hour: 50 mm/hour = 0.05 m/hour Runoff Rate = (200 m²) x (0.05 m/hour) = 10 m³/hour Convert m³/hour to liters/minute: 10 m³/hour = (10 x 1000) liters/hour = (10000/60) liters/minute ≈ 166.67 liters/minute This result helps determine the size and capacity of the stormwater drainage system needed. 2.2 Plumbing Systems Plumbing systems deliver potable (drinking) water to fixtures and appliances and remove wastewater.

Key components include: Water Supply Pipes: These pipes carry potable water from the municipal water supply to various fixtures. Common materials include copper, PVC, and PE

X. Fixtures: These are devices that use water, such as sinks, toilets, showers, and bathtubs.

Fittings: These are components used to connect pipes and fixtures, such as elbows, tees, couplings, and valves.

Valves: These control the flow of water, allowing you to shut off water to specific fixtures or the entire building for maintenance or repairs. Gate valves, ball valves, and check valves are common types.

Traps: These are U-shaped pipes installed under sinks and other fixtures to prevent sewer gases from entering the building. The trap always holds a small amount of water, creating a seal.

Vent Pipes: These pipes allow air to enter the drainage system, preventing a vacuum from forming that could siphon water out of traps. They also allow sewer gases to escape safely.

Ventilation in Plumbing Systems: Proper ventilation is crucial for maintaining a functional and sanitary plumbing system.

Vent pipes prevent: Siphonage: A vacuum in the drainage system can suck water out of traps, allowing sewer gases to enter the building.

Backpressure: Positive pressure in the drainage system can force wastewater back into fixtures.

Slow Drainage: Lack of ventilation can create airlocks, slowing down the flow of wastewater.

Common types of vent pipes include: Individual Vent: A vent pipe that connects directly to the trap arm of a fixture.

Common Vent: A vent pipe that serves multiple fixtures.

Wet Vent: A section of drain pipe that also serves as a vent. This is typically allowed only for fixtures on the same floor level.

Vent Stack: A vertical vent pipe that extends through the roof. 2.3 Sanitation Fixtures Sanitation fixtures are designed to collect and remove human waste.

The most common fixtures are: Toilets: These use water to flush waste into the drainage system. There are various types of toilets, including flush toilets, composting toilets, and urine-diverting toilets.

Urinals: These are primarily used in public restrooms for male urination.

Bidets: These provide a water spray for personal hygiene after using the toilet.