1. INTRODUCTION
This document is established to ensure that the Manhole construction and installation works of HDPE pipe and isolation gate valve are executed and to ensure that the work shall be carried out in a controlled and systematic manner and conform to the specified requirements.
2. SCOPE OF WORKS
The work applies to the Manhole construction and storage, delivery and installation for the HDPE pipe and the isolation gate valve.
3. METHOD STATEMENT
3.1. The pit is excavated to its required depth to receive the concrete base for the construction of the manhole. The base shall be adequate in length to receive the outside concrete surrounding the manhole. The position of the manhole shall be checked to keep away from misalignment of pipes down and upstream of the manhole.
3.2. Shoring to the pit shall be provided if the pit measured from the top edge is more than 1.5m.
3.3. Excavate further to the desired level manually to achieve the required level.
3.4. Excavate a sump pit at the bottom of the pit for de-watering.
3.5. Prepare formwork to receive base for the positioning of the manhole and eventual concrete to the external of the manhole.
3.6. Cast the base and allow the concrete to set for the next day to position the pre-cast concrete reinforced chamber rings.
3.7. Break or puncture a hole through the chamber ring for the inlets and prepare the box-outs at the hacked openings before the 150mm concrete surround to the external of the manhole.
3.8. Remove the formwork to the concrete surround the next day and lay the main drain lines to the openings of the manhole.
3.9. Prepare to cast the main drain at the end of the day.
3.10. Remove all formwork in the trench and at the pit of the manhole.
3.11. Backfill once the pit and trench are cleared of debris.
3.12. Apply sulphate-resistant cement to the internal of the manhole.
3.13. Render smooth gaps between chamber rings.
3.14. Proceed to render the benching with cement mortar and construct the channels with glazed vitrified half channels according to the numbers of main or branch drain lines.
3.15. Place/cut the HDPE pipe with the required size and length inside the manhole.
3.16. Joint the HDPE pipes and fittings with butt fusion saddle heater- Electro fusion flange connection for transition fittings for joining HDPE pipe to other fittings pipes gate valves installation.
3.17. Place the isolation gate valve inside the manhole using hydraulic block (chain block) exact level of HDPE pipe flanges. Connect both sides flanges of HDPE pipe and isolation gate valve. Heading upward above the ground.
3.18. Joint and connect the HDPE pipe ends with G.I. flange butt fusion saddle heater- Electro fusion.
3.19. Form up the opening to the manhole with timber and wait for the commencements of the external finishes work by the builder before installing the approved type of frame and covers
3.20. Call for Inspection.
4. MATERIAL
4.1. Timber for formwork
4.2. Glazed vitrified clay half channels of various sizes.
4.3. Portland cement and plastering sand
4.4. Manhole frame and cover.
4.5. BRC or rebar
4.6. Grade 20 concrete.
4.7. HDPE pipe and fittings
4.8. G.I. Flange schedule No. 40 with built in rubber gaskets
4.9. Isolation Gate Valve PN 16 with built in rubber gaskets
5. MACHINERY
5.1. Man-operated excavator
5.2. Hand-held cutter
5.3. Rammer
5.4. Levelling equipment
5.5. Joining machines (Butt fusions saddle heater- Electro fusion) All complying with the specifications and standards & safety plan.
5.6. Grinders with guards and plugged cable ends.
5.7. Hand tools (wrenches, mallet) of required size.
5.8. Lifting tools (chain blocks – Hydraulic jacks)
6. MANPOWER
6.1. Resident Engineer
6.2. Supervisor
6.3. QC Inspector
6.4. Excavator operator
6.5. Butt fusion welder operator
6.6. General workers
7. SAFETY & ENVIRONMENT
7.1. Safety
The following KEY POINTS is to take for the safe working practice and should be observed by all workers as well as sub-contractor’ workforce who are involved to carry them out within the company’s or its client’s premises.
7.1.1. Wear Plain, tough, close-fitting clothing and keep them buttoned up.
7.1.2. Wear Safety shoes or boots and keep them in good repair.
7.1.3. Wear Hand gloves when holding objects which are hot, sharp-edged, and covered with chemical or oily surfaces.
7.1.4. Wearing a safety helmet at the construction site.
7.1.5. Use ear protection devices and masks where necessary.
7.1.6. In addition, the personnel protection equipment shall be practiced all the time such as wearing Safety Helmet, Safety
7.1.7. Shoes, Eye Goggles, Safety belt, welding Mask, Visible jackets etc.
7.2. Environment
All workers shall be responsible and ensure that the site works carried out shall conform to the Employer’s Environment Policy and comply with the Environment Act 1974 and any other Federal and State Government act. All EMPLOYEES/WORKFORCE shall;
7.2.1. Any waste and unwanted installation materials arising from the works are not harmful and do not cause deposits and contamination in drains and sewers.
7.2.2. Keep roads and footpaths clear of mud, unwanted installation debris, boxes and the like. Cooperates with Main Contractor and the employer in this respect.
7.2.3. Ensure that existing services are not damaged and are maintained in good order.
7.2.4. Take effective action to protect occupies of adjacent buildings or land, and the public from any danger, discomfort, disturbances, trespass, or nuisance.
7.2.5. Take effective measures to reduce the nuisance from dust during the site installation works.
7.2.6. Take effective measures to minimize the noise from the installation works.
8. Emergency Contact Numbers
Project Engineer
HSE Engineer
Police
Ambulance
Fire
9. Manpower Resourcing
Project Engineer
Technician
Helper
10.INSPECTION & TEST PLAN
All work-in-progress shall be inspected by the designated project staff and the site resident engineer/site clerk of work at various inspection points as per the relevant project quality plan. Refer to the attachment.
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