Surface Prep and Coating Systems for Equalization tanks in Wastewater

Water treatment equalization tanks play a critical role in maintaining consistent flow rates and stabilizing water quality throughout treatment processes.

High Performance Coatings

What are Equalization Tanks and why are they used in municipal wastewater applications?

Surface Prep and Coating Systems for Equalization tanks in Wastewater Exposure

Water treatment equalization tanks play a critical role in maintaining consistent flow rates and stabilizing water quality throughout treatment processes. However, the success and longevity of these systems heavily depend on proper surface preparation and coating selection. The chemical environments in pre-equalization and post-equalization tanks present unique challenges that require proven, high-performance coating systems like those offered by Tnemec and Epoxytec.

Understanding the Operating Environments

Pre-Equalization Tanks

Pre-equalization tanks receive raw, untreated water containing variable concentrations of suspended solids, organic matter, and potentially aggressive chemicals. These tanks experience:

Fluctuating pH levels (typically 6.0-8.5)
High concentrations of suspended solids and debris
Potential presence of oils, greases, and organic contaminants
Temperature variations based on seasonal and process conditions
Mechanical stress from mixing equipment and flow dynamics

Post-Equalization Tanks

Post-equalization tanks handle partially or fully treated water with more stable chemical characteristics. However, they still face challenges including:

Residual treatment chemicals (chlorine, ozone, or other disinfectants)
More consistent but potentially elevated pH levels
Lower but still present suspended solids
Potential biofilm formation on surfaces
Continued mechanical stress from pumping and mixing operations

Critical Surface Preparation Requirements

Assessment and Planning

Before any surface preparation begins, conduct a thorough assessment of existing conditions. Document surface contamination, existing coating failures, substrate condition, and environmental constraints. This evaluation determines the appropriate preparation method and coating system selection.

Substrate Preparation Standards

For both tank types, achieve a minimum surface preparation standard equivalent to ICRI CSP 5 (Concrete Surface Profile). This level removes all loose material, laitance, curing compounds, and previous coatings while creating the optimal surface profile for coating adhesion to concrete substrates.

Key preparation steps include:

Complete removal of all loose material, laitance, and failed coatings
Creation of an angular surface profile between 2-4 mils (50-100 microns)
Removal of all abrasive residue and contaminants
Verification of concrete moisture content and pH levels
Maintenance of proper environmental conditions (temperature, humidity, dew point)

Environmental Controls

Maintain strict environmental controls during preparation and application. Surface temperature must remain at least 5°F above dew point, with relative humidity below 85%. Wind conditions should not exceed specifications for the chosen application method.

Proven Coating System Solutions

Tnemec System: Series 218 Resurfacer and Series 436

Tnemec Series 218 Resurfacer serves as the foundation for this high-performance system. This two-component, water-based cementitious epoxy surfacer provides excellent adhesion to properly prepared concrete surfaces while offering up to 1" application thickness per coat. The Series 218 penetrates into the concrete substrate and creates an ideal monolithic base for the subsequent topcoat application.

Tnemec Series 436 represents a premium solution for demanding water treatment environments. This high-build, glass-flake reinforced epoxy coating provides exceptional chemical resistance, abrasion resistance, and long-term durability when applied over concrete substrates. Applied at 80-125 mils DFT, Series 436 creates a robust barrier against the harsh conditions found in both pre-equalization and post-equalization tanks.

Key advantages of the Tnemec system:

Proven performance in municipal and industrial water treatment facilities
Excellent chemical resistance to chlorine, ozone, and other treatment chemicals
Superior mechanical properties including impact and abrasion resistance
Low permeability preventing substrate deterioration
Excellent adhesion characteristics to concrete when applied over Series 218

Epoxytec System: Ceramico Resurfacer and CPP Sprayliner

Epoxytec Ceramico functions as an advanced resurfacing primer that combines the benefits of epoxy chemistry with reinforcement. This innovative formulation provides exceptional adhesion to concrete substrates while offering enhanced surface build and durability compared to conventional surfacers.

Epoxytec CPP Sprayliner at 125 mils DFT delivers outstanding protection for water treatment applications. This high-build, structural and chemically resistant coating incorporates advanced polymer technology to provide superior performance against aggressive chemicals, mechanical abuse, and long-term environmental exposure when applied over concrete substrates.

Key advantages of the Epoxytec system:

Advanced ceramic-reinforced primer technology
Exceptional chemical resistance to acids, bases, and oxidizing agents
Structural Epoxy
Superior mechanical properties and impact resistance
Excellent spray application characteristics for efficient installation
Proven performance in challenging industrial environments

Application Specifications by Tank Type

Pre-Equalization Tanks

Tnemec System Application:

Surface Preparation: ICRI CSP 5 profile on concrete substrate
Tnemec Series 218 Resurfacer: Apply up to 1" as a surfacer (down to feather finish)
Tnemec Series 436: Apply at 80-125 mils DFT as finish coat

Epoxytec System Application:

Surface Preparation: ICRI CSP 5 profile on concrete substrate
Epoxytec Ceramico: Apply up to 1" as a surfacer (down to feather finish)
Epoxytec CPP Sprayliner: Apply at 125+ mils DFT as finish coat

Post-Equalization Tanks

Both systems provide excellent protection for post-equalization environments. The choice between Tnemec and Epoxytec systems often depends on specific chemical exposures, application preferences, and project requirements.

Tnemec System: The proven combination of Series 218 and Series 436 offers reliable, long-term protection against treatment chemicals and mechanical stress.

Epoxytec System: The advanced Ceramico/CPP Sprayliner combination provides enhanced chemical resistance and may be preferred for facilities with below grade structures where a structural epoxy is needed for I&I protection.

Application Best Practices

Material Handling and Mixing

Both systems require careful attention to material handling and mixing procedures. Follow manufacturer specifications exactly for:

Material storage temperatures
Mixing ratios and procedures
Pot life limitations
Application temperature ranges
Humidity requirements

Application Techniques

These high-build systems require skilled application techniques:

Spray Application: Use plural component spray equipment properly calibrated for each material. Maintain consistent spray patterns and overlap to ensure uniform thickness.

Thickness Control: Monitor wet film thickness continuously using appropriate gauges. Both systems require significant material buildup, making thickness control critical for performance and economy.

Environmental Monitoring: Maintain strict environmental controls throughout application. Document temperature, humidity, and dew point conditions.

Quality Control and Inspection

Pre-Application Inspection

Verify surface preparation standards using ICRI Visual Concrete Surface Analysis
Confirm surface profile using replica tape or digital gauges
Test concrete moisture content and pH levels
Document environmental conditions

During Application

Monitor wet film thickness continuously
Verify proper mixing ratios and procedures
Document application rates and coverage
Ensure proper substrate moisture conditions

Post-Application Verification

Measure final dry film thickness using magnetic gauges
Perform 100% holiday detection at appropriate voltage levels
Conduct adhesion testing per ASTM D4541 when required
Document final system thickness and appearance

Performance Expectations and Maintenance

Service Life Projections

When properly applied, both systems can provide:

Tnemec System: 15-20+ years of service life with exceptional chemical resistance
Epoxytec System: 15-20+ years of service life with structural characteristics

Maintenance Requirements

Both systems require minimal maintenance when properly applied:

Annual visual inspections
Immediate repair of any mechanical damage
Periodic cleaning to remove biofilm or deposits
Touch-up of minor coating defects before they propagate

Performance Monitoring

Establish baseline measurements and monitor coating performance over time:

Document any changes in appearance or performance
Track maintenance requirements and costs
Evaluate system performance against expectations
Use performance data to optimize future specifications

Cost-Benefit Analysis

Initial Investment

While both systems represent premium coating solutions with higher initial costs, they provide exceptional value through:

Extended service life reducing replacement frequency
Minimal maintenance requirements
Reduced downtime for repairs
Enhanced asset protection

Total Cost of Ownership

Consider the total cost of ownership over the system's service life:

Material and application costs
Maintenance and repair expenses
Downtime costs for recoating
Asset replacement costs

Both Tnemec and Epoxytec systems typically provide lower total cost of ownership compared to conventional coating systems due to their extended service life and reduced maintenance requirements.

Conclusion

Water treatment equalization tanks require robust protection from specialized coating systems designed for their unique challenges. Both the Tnemec Series 218/436 system and the Epoxytec Ceramico/CPP Sprayliner system offer proven solutions with excellent performance records in similar concrete applications.

The Tnemec system provides time-tested reliability with the glass-flake reinforced Series 436 offering exceptional chemical and mechanical resistance on concrete substrates. The Epoxytec system delivers advanced technology with ceramic-reinforced primer and high-performance sprayliner capabilities specifically formulated for concrete tank environments.

Selection between these systems should be based on specific project requirements, chemical exposures, application preferences, and long-term performance expectations. Both systems require proper concrete surface preparation, skilled application, and quality control measures to achieve optimal performance.

By partnering with qualified coating contractors experienced in these premium systems and following manufacturer specifications precisely, water treatment facilities can achieve decades of reliable protection for their critical concrete equalization tank infrastructure while minimizing total lifecycle costs.