RISER SHAFT HIGH FLOW LEAK - BASEMENT CARPARK - SUTHERLAND SHIRE
Project Type: Multi-residential
Location: Sutherland Shire, NSW
Client: Builder
Challenge: Confined space conditions and hydrostatic pressure due to active leak
Repair Method: Penetron System
Scope: Halt leak in mechanical riser shaft
Outcome: Water flow stopped completely within 48hrs
Project Overview
TruBond Concrete Repairs was engaged to undertake specialist water ingress remediation within a mechanical services riser shaft at a building in the Sutherland Shire, Sydney. The shaft was experiencing significant groundwater ingress through defects in the surrounding concrete structure, with the volume of water entering sufficient to cause ongoing accumulation within the confined space.
The severity of the leak required water to be pumped out of the shaft before remediation works could commence. With access restricted and the source of water ingress located within an enclosed below-ground area, conventional external waterproofing methods were impractical.
TruBond utilised a Penetron cementitious waterproofing system to treat the affected concrete and arrest the active water ingress from the accessible, negative side of the structure.
Access hole of the riser shaft while water pumpout is occuring
The Challenge
The primary challenge was the combination of high-flow active water ingress and restricted access within the mechanical riser shaft. Water was entering through defects in the concrete at a rate that caused the shaft to accumulate substantial volumes of water, requiring dewatering before the affected areas could be accessed.
The confined nature of the shaft introduced additional challenges associated with worker access, ventilation, equipment handling and the limited space available to undertake concrete preparation and waterproofing repairs. The presence of mechanical services and restricted working clearances further complicated the remediation process.
Unlike conventional basement waterproofing, where large wall surfaces can be accessed relatively easily, the repair required targeted treatment within a narrow enclosed space. The waterproofing system also needed to withstand the groundwater pressure acting against the outside of the concrete, without requiring excavation or access to the positive side of the structure.
High flow leak prior to treatment
Remediation Strategy
TruBond implemented a targeted negative-side waterproofing methodology using a Penetron system designed to treat active water ingress through concrete defects.
The remediation works involved:
Dewatering: Accumulated water was pumped from the riser shaft to provide access to the affected concrete and allow the repair works to proceed.
Leak identification: The exposed concrete was inspected to identify the principal water ingress locations and determine the areas requiring treatment.
Concrete preparation: Defective and unsound material was removed from the affected areas to expose a suitable substrate for the waterproofing repair.
Active leak treatment: The high-flow water ingress locations were treated using the specified Penetron waterproofing system to control the active leakage.
Final inspection: The treated areas were inspected to assess the effectiveness of the remediation and identify any remaining visible water ingress.
The repair methodology was selected to address the active leaks directly from within the riser shaft. Due to the large gaps, honeycombing and general concrete defects injection was not the best option here and Penetron excelled instead.
Project Outcome
The Penetron remediation system successfully controlled the high-flow water ingress within the mechanical riser shaft, allowing the affected concrete areas to be reinstated without external excavation.
By treating the leakage pathways directly from the negative side, TruBond delivered a practical waterproofing solution despite the significant access restrictions and challenging working conditions.
The project demonstrates the importance of selecting a repair methodology suited to both the water ingress mechanism and the physical constraints of the structure. Active leaks within enclosed riser shafts, lift pits and below-ground service areas can present considerable challenges, particularly where groundwater accumulation prevents safe access to the affected concrete.
TruBond Concrete Repairs specialises in active water ingress remediation throughout Sydney, including underground car parks, mechanical riser shafts, lift pits, basements and other below-ground reinforced concrete structures. Our services include negative-side waterproofing, crystalline waterproofing, construction joint remediation and pressure injection systems for active concrete leaks.
Post treatment, all active flow stopped. The water glisten or “repair sweat” is often seen in the Penetron system, drying completely over the coming days and weeks
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Whether you're dealing with concrete spalling, reinforcement corrosion, structural deterioration or water ingress, TruBond Concrete Repairs delivers tailored remediation solutions designed for long-term performance.
From residential projects through to large commercial developments, our team combines proven repair methodologies with high-quality materials to restore both the durability and appearance of reinforced concrete structures.