Fixing Surface Water Drainage with Absorption Trenches – Epping

Managing Surface Water with an Absorption Trench System – Epping

Surface water runoff is a common drainage issue for residential properties. During heavy rainfall, stormwater can collect in yards, run across paved areas, or overwhelm existing drainage systems.

At this property in Epping, the homeowner was experiencing water buildup toward the rear section of the yard. The existing stormwater system was not dispersing runoff effectively, which meant water was concentrating in specific areas of the lawn.

Over time this type of issue can lead to saturated soil, lawn damage, erosion, and water movement toward the building foundations.

Our team attended the property to investigate the existing drainage infrastructure and design a stormwater solution that would safely manage runoff while preventing surface pooling.

This type of work falls under our Stormwater Drainage, Drainage Solutions, and Surface Water Management services.

Understanding Why Surface Water Was Building Up

When properties experience drainage issues like this, the cause is not always obvious. Water pooling on the surface can be caused by several factors including:

• Poor ground gradients
• Inadequate stormwater discharge capacity
• Blocked or partially obstructed pipes
• Concentrated runoff from roof drainage
• Soil that drains slowly

Before recommending a solution, we first needed to assess how water was travelling through the property’s drainage system.

Inspecting the Existing Stormwater System

The first step in the investigation was marking out the proposed locations for new absorption trenches and checking ground levels across the yard. Stormwater pipes rely on gravity, so measuring the correct fall is critical when designing drainage systems.

We excavated sections of the property to expose the existing stormwater pipework and identify the best connection points for the new drainage system.

To gain a clearer understanding of the underground pipe network, we also carried out a CCTV Pipe Inspection. This involves feeding a specialised waterproof camera through the stormwater pipes to inspect their condition.

CCTV inspections allow plumbers to determine:

• Pipe depths and alignment
• Connection points
• Obstructions or debris buildup
• Structural pipe damage
• Areas of poor drainage flow

While inspecting the pipes, we also performed Drain Cleaning using high-pressure water jetting to clear any sediment and ensure the existing lines were flowing properly before connecting the new system.

Installing the Absorption Trench System

Once the investigation was complete, we began constructing the stormwater absorption system.

Three trenches were excavated measuring approximately six metres long, 500mm wide and one metre deep. These trenches form the underground structure that will temporarily hold stormwater before allowing it to disperse into the surrounding soil.

Each trench was lined with geotextile fabric. This material acts as a filtration barrier that allows water to pass through while preventing soil from entering and clogging the system.

We then installed three jumbo arch infiltration modules in parallel configuration. These modular structures create large underground voids that store stormwater during heavy rainfall events.

New PVC pipework was installed to connect the property’s existing stormwater drainage network to the absorption trenches. Inspection openings were also included so the system can be easily accessed for future maintenance if required.

An additional overflow drainage line was installed at the rear left-hand side of the property to provide an extra discharge pathway during heavy rain events.

Backfilling and Restoring the Yard

Once the infiltration modules were installed, the trenches were backfilled with 20mm aggregate. The aggregate allows water to move freely through the trench while supporting the surrounding soil structure.

The system was then wrapped in geotextile fabric to complete the filtration layer and prevent soil intrusion.

After the drainage system was secured, the remaining excavated areas were backfilled with soil and approximately 15 square metres of turf was reinstated to restore the lawn surface.

Testing and Commissioning the Drainage System

After installation was complete, the stormwater system was tested to confirm proper operation.

Water flow through the new pipework was checked, and the absorption trenches were inspected to ensure they were capturing and dispersing runoff effectively.

Once the system was confirmed to be operating correctly, the site was cleaned, and all waste materials were removed.

The property now has a stormwater drainage system designed to safely store and disperse surface water underground, reducing pooling and protecting the surrounding landscape.

When Absorption Trench Drainage Systems Are Used

Absorption trench systems are often installed when properties experience ongoing surface water management issues.

They are commonly recommended when:

• Stormwater runoff collects in lawns or low-lying areas
• Existing stormwater outlets cannot handle heavy rainfall
• Properties need additional underground drainage capacity
• Soil conditions allow water to infiltrate gradually
• Surface drainage needs to be improved without large above-ground structures

Installing an absorption trench can significantly improve how stormwater is managed across a property while preventing runoff from damaging landscaping or nearby structures.

If you’re experiencing water pooling around your property or your stormwater system struggles during heavy rain, a professional investigation can help identify the right drainage solution.

Call 0483915451 to speak with our team about Stormwater Drainage, CCTV Pipe Inspection, or Drainage Solutions, or click Book Now to arrange a site inspection.