Headworks

1.Purpose:

This work instruction provides detailed guidelines for the construction and installation of the headworks system in a water treatment facility. The headworks system includes the screening, grit removal, and flow measurement equipment.

2. Scope:

This instruction applies to all personnel involved in the construction and installation of the headworks system, including engineers, site supervisors, construction workers, and QA/QC inspectors.

3. Responsibilities:

• Project Manager: Oversees the entire project, ensuring completion within the schedule, budget, and quality standards.
• Site Supervisor: Manages daily activities, ensuring compliance with safety protocols and coordination among teams.
• Construction Team: Executes the construction and installation work as per instructions, reporting any issues to the Site Supervisor.
• QA/QC Inspector: Verifies that construction and installation meet design specifications and quality standards.
• Installation Team: Handles the installation of mechanical, electrical, and control systems for the headworks.
• HSE Officer: Ensures that all safety and environmental regulations are adhered to during the construction and installation process.

4. Safety Considerations:

• All personnel must wear appropriate PPE (hard hats, safety glasses, gloves, safety boots, high-visibility vests).
• Conduct a Job Hazard Analysis (JHA) before starting work to identify potential hazards.
• Implement lockout/tagout procedures for all electrical and mechanical systems.
• Ensure compliance with OSHA standards for excavation, confined spaces, and working at heights.
• Provide training on the use of lifting and handling equipment.

5. Tools and Equipment:

• Excavators and backhoes
• Cranes and lifting equipment
• Concrete mixers and vibrators
• Welding equipment (if required)
• Hand tools (wrenches, screwdrivers, hammers, etc.)
• Laser levels and measuring tapes
• PPE (Personal Protective Equipment)
• Electrical testing and commissioning tools
• Scaffolding and formwork materials

6. Materials:

• Concrete and reinforcement bars
• Precast or fabricated headworks structures (screens, grit removal units, flow measurement devices)
• Masonry materials (bricks, mortar, etc.)
• Structural steel (if required)
• Pipes and fittings
• Sealants and adhesives
• Grout and anchors
• Electrical wiring and control panels
• Waterproofing materials

7. Procedure:

7.1 Pre-Construction and Pre-Installation Activities

1. Site Survey and Preparation:

• Conduct a thorough site survey, ensuring proper grading and drainage.
• Mark the location of the headworks system using survey stakes and laser levels.
• Clear and level the site as per the design specifications.
• Ensure all utilities (electrical, water, etc.) are marked and protected.

2. Review Drawings and Specifications:

• Review the latest construction drawings, specifications, and applicable addendums.
• Verify that all materials are on-site and conform to specifications.

3. Excavation and Foundation Preparation:

• Excavate the area according to the design dimensions.
• Install formwork for the foundation, ensuring correct alignment and levels.
• Place reinforcement bars as per design drawings, ensuring proper spacing and cover.
• Pour and cure concrete for the foundation as per the manufacturer's recommendations.

7.2. Construction of Headworks Structures

1. Concrete Work:

• Construct the concrete structures for channels, tanks, and foundations, including setting up formwork, placing reinforcement, pouring, and curing the concrete.
• Ensure proper compaction and finishing of the concrete surfaces.

2. Masonry and Structural Work:

• Build walls, chambers, and other structural elements that will house the mechanical components of the headworks.
• Apply necessary waterproofing measures to protect the structures from water ingress and environmental damage.

3. Installation of Custom Fabricated Components:

• If required, fabricate custom components such as gates, screens, and channels on-site, ensuring they meet the design specifications.
• Install these components securely within the concrete or masonry structures.

7.3. Installation of Headworks System

1. Setting the Structures:

• Position the headworks structures (screens, grit chambers, etc.) on the foundation using cranes.
• Ensure the structures are aligned and leveled according to design specifications.
• Anchor the structures to the foundation using grout or specified anchor systems.

2. Connecting Pipelines:

• Install the inlet and outlet pipelines to the headworks structures.
• Ensure all pipe joints are sealed and leak-tested according to the specifications.
• Install necessary valves, flow meters, and control devices.

3. Electrical and Control System Installation:

• Install control panels and connect to the electrical supply.
• Run wiring from sensors, flow meters, and other control devices to the control panel.
• Verify that all electrical connections meet safety and design standards.

4. Grouting and Sealing:

• Apply grout to seal any gaps between the headworks structures and the foundation.
• Ensure all joints and penetrations are properly sealed to prevent leakage.

5. Backfilling:

• Once all structures and pipelines are installed, backfill the excavated areas with approved material.
• Compact the backfill in layers to avoid settling.

7.4. Post-Construction and Post-Installation Activities

1. Inspection and Testing:

• Conduct a final inspection to ensure the headworks system is built and installed according to design.
• Perform leak tests on all pipelines and structures.
• Verify the operation of all mechanical and electrical components.

2. Structural Integrity Testing:

• Test the structural components for integrity, including load testing if applicable.
• Document and rectify any issues identified during the testing phase.

3. Commissioning:

• Start up the headworks system and check for proper operation.
• Adjust any settings as needed to meet operational requirements.
• Document all test results and adjustments made.

4. Environmental Compliance:

• Ensure compliance with environmental regulations, including proper waste handling and mitigation of any impact on surrounding areas.

7.5. Handover and Documentation

1. Final Documentation:

• Prepare and submit all construction and installation documentation, including as-built drawings, inspection reports, and test results.
• Ensure all records of material certificates, inspection reports, and other relevant documents are maintained.

2. Training and Handover:

• Provide thorough training to facility operators on the use and maintenance of the headworks system.
• Handover the system to the client with complete documentation and operational manuals.

8. Documentation

• Installation Checklists
• Inspection Reports
• Test Results
• As-Built Drawings
• Training Records
• Environmental Compliance Records

9. References

• Project-specific drawings and specifications
• Company procedures for excavation and confined spaces
• Manufacturer’s installation manuals for headworks components