10. Desagüe Pluvial (Parte 1) - Cátedra B. Garzón

Main ideas and concepts covered (Part 1: Stormwater drainage in buildings)

Stormwater vs. sewage systems

Every building has two independent drainage networks:

• Sewage system: manages greywater and blackwater.
• Stormwater system: manages rainwater and runoff (e.g., from washing floors and patios).
• Because they are independent, they must be designed independently.

Purpose of stormwater drainage

Stormwater drainage includes fittings and pipes to channel, transport, eliminate, or store rainwater.

Key goals:

• Evacuate rainwater quickly to prevent accumulation, which can endanger public health.
• Stormwater typically discharges into roadways or reservoirs/storage areas, unlike sewage drains.

Classification by location

• External stormwater drainage: carries rainwater from the urban environment to urban/territorial sewer networks.
• Internal stormwater drainage: carries water from the building interior out to the exterior/roadways.

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Methodology / structured content (detailed)

A) External stormwater installations (public/urban space)

System components and flow

• Rainwater from buildings flows via pipes to the roadway.
• It then drains through storm drains/catch basins connected to the storm-drain pipe network.

Urban arrangement

• Storm drains are installed in streets.
• The network uses an adequate slope to guide natural runoff.

Infrastructure example context

• Greater San Miguel de Tucumán: referenced via hydrographic/infrastructure mapping.
• Key receiver: Salí River.
• Natural streams/canals collect and direct runoff to PRD (Provincial District of Tucumán).

Maintenance lessons

• Example of obstruction: storm drains blocked by solid urban waste, worsening flooding.
• Maintenance includes:
  • Cleaning and controlling drainage sections.
  • Keeping curbs/edges clean so objects do not obstruct runoff after rainfall.

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B) Internal stormwater installations in high-rise buildings

Definition / scope

A set of pipes and accessories designed to:

• collect water falling inside the property, and
• evacuate it to the exterior through the building curb/edge area.

Core components of the internal rainwater system

• Gutter: receives runoff from pitched roofs.
• Funnels (roof drains): collect runoff from flat roofs.
• Leveling layer (topping/leveling): forms the drainage slope on slabs.
• Floor grates: on balconies and small surfaces (with restrictions; see below).
• Downpipes: vertical pipes carrying runoff to ground level/drainage level.
• Drain outlet: open or closed depending on required water reception.
• Conduit / horizontal drain (conductor/conduit): transports rainwater horizontally with the necessary slope to the final outlet/drain.

Typical materials mentioned

• Polypropylene
• PVC (polyvinyl chloride)
• Galvanized sheet metal
• Cast iron
• Materials used for masonry

Installation layout rules and restrictions (key engineering recommendations)

Funnels placement

• Located either at the center of the drainage surface or toward corners.
• Variants:
  • Vertical outlet
  • Lateral outlet
  • Funnel where water is received via a vertical grate
• The specific funnel configuration can be adapted based on pavement thickness during project design.

Horizontal conduit layout

• Provide the shortest possible pipe length.
• Maintain at least 40 cm from:
  • the property line
  • other installations such as the sewer system
• Avoid crossings/overlaps and internal connection complications.
• If necessary:
  • maximum length between drain points: 1.2 meters

Required slopes

• Horizontal pipes must have gravity-flow slope.
• The slope cannot be too steep if the pipe exits toward the street below ground level.
• From sidewalk to curb, the horizontal pipe must always slope in the direction of street water flow.
• Strictly prohibited:
  • slopes against the street (also applies to drain outlet orientation as stated)

Connection geometry

• Minimum connection angle between internal and external drains: 90°.
• Preferably 22° 30’ with the street slope (as stated).

Diameter limitation

• Diameter of the relevant horizontal element: not exceed 100 mm.

Access points (unclogging/maintenance)

Access points must be placed at:

• junctions between pipes and conduits
• junctions between different conductors

They enable easy unclogging. Example placements:

• between the downpipe and conductor
• at a 45° angle between conductors

Balcony/floor grate restrictions

• Floor grates drain surfaces smaller than 10 m².
• Permitted only if the balcony includes service taps or washbasins (as described in the cut example).
• In those cases, such open floor drains are part of the sewer system.

Prohibited/incorrect execution examples

• Roof-to-gutter error:
  • A minimum counter-slope of 60 cm is required when a gutter is placed on a party wall.
  • The incorrect case is flagged as not meeting this requirement.
• Gargoyles draining to sidewalk:
  • Direct drainage toward the sidewalk is prohibited.

Overflow / below-grade placement cautions

If a drainage level is below ground level (e.g., parking areas with overflow conditions):

• the system must avoid improper rainwater drainage.
• described as needing a pipe route from drain outlet to a waterproof post (as stated).

Sizing and pumping guidance (below-grade / insufficient elevation)

• Pump capacity calculation basis:
  • 30 liters per square meter of surface
  • maximum capacity up to 1000 liters
• Pumping procedure:
  • pump until water surpasses the drainage level on the ground floor,
  • then it flows by gravity
• Pump connection rule:
  • pump pressure can never be directly connected to the conduit
• Venting requirement:
  • if the pumping well has no grate at the top, provide additional piping to vent the accumulated rainwater space.

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C) Rainwater collection (why and how it ties to stormwater drainage)

Context / motivation

21st-century expectations:

• rising population → increasing water and resource demand

Climate-change-linked risks:

• water scarcity and droughts
• flooding and excess water

Freshwater availability decreases due to drying of lakes/rivers, including those fed by glaciers (melting).

Rainwater harvesting as a solution

• Not new historically:
  • Roman dwellings used rainwater collection ponds (including domes).
  • Byzantine/Istanbul basilica cistern: built to reduce vulnerability after the Valens aqueduct was destroyed.

Substitution potential

• In a given context, about half of water consumption can be replaced by rainwater that often does not require purification.

Local climate / precedent

Argentina precipitation context:

• summer months: around 200 mm
• annual total: about 1,250 mm

Reference to Buenos Aires City Building Code:

• Article 3.2, point 3
• Guidelines for plans/slabs above 2.60 m, with exclusions such as:
  • excluding horizontal property
  • excluding multi-family buildings under certain conditions (e.g., fewer than four stories)
  • excluding some small covered areas (e.g., less than 200 m²)
  • other cases determined by implementing authorities

Advisory principle mentioned:

• If curb/sidewalk drainage may be impossible during heavy rains, design so drainage of the first and second floors is independent of the main system.

Urban-level actions to reduce flooding/accumulation

• Avoid cutting down trees:
  • roots delay water movement
  • help preserve green spaces
  • reduce vegetation proliferation on hard surfaces
• Construct roof gardens (and similar measures).
• Promote a reuse culture for non-potable water uses that do not require purification:
  • irrigation
  • cleaning
  • storage uses (bedroom storage mentioned)
  • other non-consumption domestic uses

Residential-level measures

• Use retention tanks plus a reserve tank.
• Include rainwater storage tanks with the necessary equipment.

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Speakers / sources featured

Speakers

• The video is associated with “Cátedra B. Garzón” (course/lecturer attribution).
• No individual lecturer name is explicitly stated in the subtitles beyond the course title.

Institutional sources / standards / references

• IRAM (Argentine Institute of Standardization and Certification): stormwater drainage systems must comply with IRAM standards.
• Buenos Aires City Building Code, Article 3.2, point 3: referenced for rainwater-related planning guidelines.
• Technical catalogs used for examples (funnels and components): referenced as part of the bibliography (no specific catalog titles given).
• Historical and geographic references mentioned in-lecture (not presented as named documentary sources), including:
  • Greater San Miguel de Tucumán
  • Salí River
  • Tafí Viejo
  • PRD
  • Valens aqueduct
  • Istanbul Basilica Cistern