Properties of Materials Are Identified Based on the Job Requirements

In the field of wastewater infrastructure design and construction, the identification and selection of appropriate materials is one of the most critical decisions engineers must make. As outlined in the competency standard “Design Wastewater Collection and Treatment Infrastructure” (Unit Code: CON/OS/CET/CR/09/6A), properties of materials are identified based on the job requirements a principle that ensures infrastructure is durable, safe, and cost-effective for its intended service life.

This comprehensive guide explores how engineers identify material properties based on specific job requirements in wastewater infrastructure projects, examining the key material characteristics, selection criteria, and standards that govern this essential engineering process.

1. Understanding the Principle: Why Job Requirements Drive Material Selection

The identification of material properties based on job requirements is a fundamental engineering principle that ensures materials perform adequately under the specific conditions they will encounter. According to the American Water Works Association (AWWA), material selection depends primarily on chemical compatibility, pressure requirements, installation environment, and life cycle cost analysis .

For wastewater infrastructure, job requirements typically encompass:

The consequences of incorrect material selection can be severe. As documented in a recent study on concrete structures in sewage environments, “the concrete structure will be seriously eroded in a sewage environment, causing substantial economic losses” . These losses amount to hundreds of billions of dollars annually, highlighting the critical importance of proper material identification .

2. Key Material Properties for Wastewater Infrastructure

2.1 Chemical Resistance and pH Tolerance

Chemical resistance is perhaps the most critical material property for wastewater applications. Wastewater contains aggressive chemicals, including hydrogen sulfide, sulfuric acid, and biological acids produced by microorganisms . The corrosion effects of H₂S and biological sulfuric acid generated by microbial redox on structures have attracted significant research attention, with studies finding that the concentration of H₂S is “proportional to the degree of concrete deterioration” .

Chemical Resistance Comparison for Common Pipe Materials :

For applications involving Advanced Oxidation Processes (AOP) in wastewater treatment, material selection becomes even more critical. Research has demonstrated that “the Fenton process causes severe pitting corrosion on the stainless steel alloys” and requires materials with higher pitting corrosion resistance .

2.2 Mechanical Properties

Mechanical properties determine a material’s ability to withstand physical loads and stresses:

A study on high-performance fiber-reinforced mortar for wastewater pipelines found that “the compressive strength of the M specimens was 25.5–37.3% higher than the P specimens after 12 cycles under corrosive environments,” demonstrating how material selection directly impacts structural performance .

2.3 Physical Properties

Physical properties affect installation, performance, and longevity:

In constructed wetland systems, substrates play a major role “to filter, adsorb, sediment, flocculate, precipitate, and exchange ions.” The selection of bed materials is based on “size, hydraulic conductivity, texture, porosity, etc.” .

3. Common Materials and Their Applications

3.1 Concrete and Cementitious Materials

Concrete is widely used in wastewater infrastructure due to its cost-effectiveness, stability, and convenient construction . However, concrete performance in corrosive environments “will degrade significantly,” making proper material selection essential .

Concrete Applications in Wastewater:

ASTM C913 provides the “recommended design requirements and manufacturing practices for monolithic or sectional precast concrete water and wastewater structures” . This specification ensures quality and consistency across applications.

3.2 Pipe Materials

Pipe material selection is one of the most common and critical decisions in wastewater infrastructure design:

PVC (Polyvinyl Chloride):

• Best for cost-effective gravity sewer systems with moderate chemical exposure
• Chemical resistance from pH 2-12
• Schedule 40 rating up to 220 PSI 

HDPE (High-Density Polyethylene):

• Ideal for flexible underground installations requiring superior impact strength
• Superior chemical resistance from pH 1-14
• Flexibility prevents crack propagation 

Stainless Steel:

• Use “when handling highly corrosive wastewater, extreme temperatures, or high-pressure applications” 
• 316 Stainless Steel withstands chloride concentrations up to 1,000 ppm 

Corrosion Resistance Comparison:

Research on lean duplex stainless steel has demonstrated that using duplex grade EN 1.4062 “showed the lowest total LCC, thanks to its leaner chemical composition (i.e., lower nickel content) combined with good localized corrosion resistance” .

3.3 Mortars and Repair Materials

For repair and rehabilitation of existing structures, specialized mortars are often required:

A recent study developed a “new composite high-durability mortar by adding polypropylene fibers, basalt fibers and impermeable agents” that can “achieve the dual requirements of structural repair and protection” .

4. Design Codes and Standards for Material Identification

4.1 International Standards

Material identification and selection are governed by numerous codes and standards:

The Winnipeg Structural Design Guideline emphasizes that “all designs shall comply with municipal, provincial, and national codes and bylaws,” and concrete design shall be in accordance with CSA A23.3 “except for facilities or portions of facilities that are considered hydraulic structures,” which should be designed in accordance with ACI 350M .

4.2 Corrosion Protection Standards

For corrosion prevention, several specialized standards apply:

The Guide to Selecting Protective Treatments for Concrete (ACI 515.2) provides comprehensive guidance on corrosion protection .

5. Job Requirements Driving Material Selection

5.1 Wastewater Type and Characteristics

The type of wastewater being handled is a primary determinant of material selection:

A study on constructed wetlands emphasized that “selecting substrate or bed materials is not difficult, as locally accessible, cost-effective, and environment-friendly materials can be used based on size, hydraulic conductivity, texture, porosity, etc.” .

5.2 Installation Environment

Installation conditions significantly influence material selection:

HDPE is particularly valued for “flexible underground installations requiring superior impact strength and chemical resistance,” while stainless steel excels in “highly corrosive wastewater, extreme temperatures, or high-pressure applications” .

5.3 Regulatory Requirements

Regulatory compliance is a mandatory aspect of material identification. The design must:

• Meet discharge permit requirements
• Comply with environmental standards
• Satisfy health and safety regulations
• Adhere to building codes

The National Building Code and its amendments “shall be used in the design” of all wastewater structures, as documented in the Winnipeg Structural Design Guideline .

6. Practical Considerations for Engineers

6.1 Life Cycle Cost Analysis

Material selection must consider the full life cycle cost:

Duplex stainless steel grades showed the lowest total life cycle cost “thanks to their leaner chemical composition (i.e., lower nickel content) combined with good localized corrosion resistance” .

6.2 Construction and Installation

Material selection must consider construction requirements:

7. Conclusion

The identification of material properties based on job requirements is a fundamental engineering principle that underpins the success of all wastewater infrastructure projects. From the selection of pipe materials to the specification of concrete mixtures and protective coatings, every decision must be guided by a thorough understanding of the specific job requirements and the material properties needed to meet them.

Key takeaways for engineering practice:

1. Chemical compatibility is paramount—wastewater’s aggressive nature demands materials with appropriate chemical resistance.
2. Mechanical properties determine structural performance—strength, durability, and flexibility must match service conditions.
3. Environmental factors matter—temperature, moisture, and UV exposure all influence material selection.
4. Codes and standards provide guidance—ASTM, ACI, and CSA standards establish minimum requirements.
5. Life cycle cost analysis is essential—initial cost must be balanced against maintenance and replacement.

By following a systematic approach to material identification based on job requirements, engineers can design wastewater infrastructure that is safe, durable, and cost-effective for its intended service life.