Effluent Pit Lining

BACKGROUND

An environmental audit revealed that the client’s effluent pit, in service for over 40 years without significant maintenance, was showing substantial degradation. The below-ground construction of the tank posed challenges, including groundwater ingress and the risk of osmotic blistering if an impermeable tank lining were applied.

OUR SOLUTION

Given the tank’s age and construction, Corroless Eastern proposed Sika Sikagard® M790 for the tank lining. This solution was ideal for mitigating the risk of external groundwater intrusion and osmotic blistering. Osmotic blistering can occur when moisture penetrates a lining and reacts with soluble salts within the substrate or the coating itself, causing pressure buildup beneath the surface.

The pit was drained and cleaned, revealing significant groundwater ingress. Corroless Eastern addressed these active leaks by injecting Sika® Injection-107 foaming polyurethane resin into cracks and voids. This created a permanently elastic seal, waterproofing the structure effectively.

All internal surfaces were prepared using vacuum-controlled diamond grinding, ensuring a clean and profiled surface for optimal adhesion of the new tank lining.

SikaTop® Seal-586, a cementitious waterproofing system, was applied to the pit’s internal surfaces. This step provided both waterproofing and a smoother surface, removing irregularities in the brickwork and creating an ideal base for the tank lining.

Before and during the resin application, climatic conditions were closely monitored to align with manufacturer recommendations, ensuring optimal product performance.

Tank Lining Application

1. Priming
All surfaces were primed with Sikagard® P770, a primer specifically designed for below-ground applications and suitable for use over freshly applied cementitious materials. The primer was applied using brushes and rollers.

2. Top Coating
The first coat of Sikagard® M790, applied via brush and roller, achieved a target thickness of 500 microns. Wet film thickness measurements were taken to ensure proper application. A second coat, in a contrasting color, was then applied to verify full coverage and compliance with best practices.

The fully cured coating was tested for porosity using a DC holiday spark tester. This step ensured no pinholes existed, as even a single defect could allow aggressive chemicals, like hydrogen sulfide or biogenic sulfuric acid, to attack the substrate and compromise the new lining.

Corroless Eastern delivered a robust and durable solution, ensuring the long-term functionality and integrity of the effluent pit. With Sika products, the pit is now well-protected against degradation, groundwater ingress, and the demanding operational environment.

           BENEFITS

Enhanced Durability: The use of Sika Sikagard® M790 and supporting products provides a long-lasting, high-performance lining system designed to withstand aggressive effluent and environmental conditions.

Groundwater Protection: The combination of Sika® Injection-107 for leak sealing and Sikagard® P770 primer ensures the structure is resistant to groundwater ingress, preventing future structural issues and maintaining the integrity of the lining.

Quality Assurance: Comprehensive surface preparation, climatic monitoring, and porosity testing ensured a flawless application, eliminating risks of failure due to pinholes or suboptimal application conditions..

Project Duration: Completed within [specific timeframe, e.g., 4 weeks] to minimize downtime and ensure a swift return to operation. 

Surface Area Treated: [Specific area, e.g., 120 m²] of effluent pit surfaces refurbished with a multi-layer lining system for long-term durability.