Xpedite Stormwater & Drainage experts were engaged to investigate and design a permanent rectification solution to this domestic property in Wallsend.

Investigation & Design

An on-site inspection confirmed:

• High groundwater movement toward the lower section of the dwelling
• Hydrostatic pressure against external retaining walls
• Inadequate subsoil drainage provisions
• Stormwater discharge requiring review to ensure capacity for additional drainage loads

A full subsoil drainage and waterproofing system was designed to intercept groundwater before reaching the structure.

Scope of Works

Excavation & Preparation

• Excavation around the exterior lower-level walls to approximately 2 metres depth (or to rock bed where encountered)
• Cleaning and priming of exposed retaining walls
• Application of a two-coat waterproofing membrane system

Subsoil Drainage Installation

• Installation of a geofabric-lined trench
• Installation of an ag-line at the base of the trench to intercept groundwater
• Backfilling with 10mm drainage aggregate to cover ag-line
• Wrapping of geofabric and reinstatement of remaining soil

Discharge & Stormwater Integration

• Penetration through the retaining wall to connect the new ag-line discharge
• Installation of a new discharge line to the 450 mm service pit at the driveway
• CCTV inspection of existing drainage to confirm downstream capacity
• Installation of a new downpipe discharge line connected to a 450 mm service pit
• Connection of all existing downpipes into the new system

Completion

• Testing and commissioning of all new drainage works
• Site clean-up prior to departure

Outcome

• Eliminated groundwater ingress into the subfloor
• Prevented further flooding of the garage and lower-level bedrooms
• Reduced hydrostatic pressure against retaining walls
• Delivered a compliant, long-term drainage and waterproofing solution