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An underdrain is a drainage system typically consisting of a 4-inch plastic drain tile installed along the edge of pavement, approximately 40 inches deep. The purpose of the underdrain is to remove excess water from the road subgrade to prevent pavement damage and extend the life of the road.
Key Points:
- Material: Usually made of 4-inch plastic drain tile.
- Installation Depth: Typically installed about 40 inches below the surface.
- Drainage: The drain tile is “daylighted” periodically at low points in the topography, usually discharging into nearby streams.
Installation Process:
- Trenching: A specialized machine digs the trench to the required depth along the edge of the pavement.
- Drain Tile Installation: The machine simultaneously installs the drain tile in the trench.
- Backfill: Another machine places backfill material (usually gravel or sand) into the trench over the drain tile.
- Compaction: Equipment is used to compact the backfill material to ensure stability and proper drainage.
- Cleaning: A tractor-mounted rotary broom cleans up any debris or excess material from the installation process.
- Outlet Installation: A truck and backhoe crew installs outlets from the drain tile to the streams or other discharge points. These outlets are spaced at intervals corresponding to low spots in the topography.
Equipment Used:
- Trenching Machine: Digs the trench and installs the drain tile.
- Backfill Placement Machine: Places backfill material into the trench.
- Compaction Equipment: Compacts the backfill to ensure stability.
- Rotary Broom: Cleans up the area after installation.
- Backhoe and Truck Crew: Installs the outlets for water discharge.
Timeframe:
- Duration: The process typically takes one to two weeks for a particular road project, depending on the length of the road section being worked on.
Benefits:
- Water Management: Effectively manages subsurface water, preventing damage to the pavement structure.
- Longevity: Helps extend the life of the pavement by reducing water-related damage.
- Efficiency: A streamlined process using specialized equipment ensures quick and efficient installation.
Applications:
- Road Construction and Maintenance: Commonly used in road construction projects to manage water drainage.
- Landscape Drainage: Can be used in other areas requiring effective subsurface drainage, such as sports fields or agricultural lands.
Underdrains are a critical component in road construction and maintenance, ensuring proper drainage, preventing water-related damage, and extending the lifespan of the pavement. The installation process, although complex, is highly efficient with the use of specialized machinery and a systematic approach.
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