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Method Statement for Stormwater Drainage

Below is precise method statement for drainage works covering sanitary, vent and stormwater pipes.

Stormwater drainage is an important system for any kind of construction project.

This plumbing method statement covers the installation of sanitary, vent and stormwater drainage piping system.

The purpose of stormwater drainage installation procedure is to ensure that drainage and vent piping have been installed as per the contract requirements and project specifications.

Necessary Materials

Plant and Equipment for Storm Water Drainage Installation

a. Tools and Equipment Schedule

b. Personnel Protective equipment: All personnel should wear at all time safety shoes, helmet and coverall.

c. Working Platforms: Scaffolding as required within the specific work area.

Roles and Responsibilities

Overall project manager is responsible for the implementation of this plumbing method statement on site.

Mechanical engineers will monitor all work on site in order to ensure that all standards and specs are being followed and that the work being executed is of the highest levels of professionalism and accuracy.

Quality Control engineer inspects and ensures the construction and fabrication work for storm drainage is carried out according to project’s standards and specifications.

Safety Officer shall be responsible for the implementation of Health and Safety aspects on site as per approved Health & Safety Manual requirements.

Foremen shall be present on site at all time to give out the correct instructions and coordination with the technician and other staff assigned to his area, while ensuring the work required are being implemented accordingly based on the mechanical standard and project schedule.

Qualified technicians shall be responsible to ensure the best quality of drain piping , also to ensure that works are executed progressively as per schedule.

Store keepers shall ensure that the materials are stored in safe environment with proper conditions of storage.

Safety officers shall guarantee that all personnel are abiding by the safety rules and regulations of site work.

Storage and Handling of  Materials

All materials stored on site are monitored by qualified storekeepers that ensure they are in good conditions and safe from environmental conditions that might endanger them ( e.g. moisture, heat, dust and friction etc. )

Materials shall be stocked and stored in safe space to prevent from deterioration and damage, the delivered material shall be checked to conform to the project specifications.

As for the handling, workers are instructed to treat all equipment and materials with care and engineers as well as foremen shall monitor the material handling process for extra assurance.

Health and Safety

Health and safety standards as per project hse plan are always implemented on site through experienced health and safety officers and engineers.

HSE team shall ensure prevention of accidents and control all safety hazards that might lead to serious injuries, it is compulsory to use approved Personal Protective Equipment PPE.

Environmental Requirements

All construction related works shall be executed to the highest levels of quality while at the same time avoiding any operation that might endanger the environment.

Therefore, materials are carefully chosen to be as environment friendly as possible.

Any hazardous material is carefully stored as mentioned in material safety data sheets MSDS and scrap materials are carefully and safely disposed off.

Sequence of Work

Submittal / approval of drawings for construction of drainage piping system.

Submittal / approval of materials.

Check availability of material and lead time to order material.

Clean pipes and fittings, remove oil, grease and any other loosely adhering deposits

Carefully unload required lengths and sizes of pipes in storage and to the work area.

Keep the materials in good storage conditions, special care must be taken to protect the units from moisture, corrosion and dust.

Pipes must be stored horizontally with adequate support and handled with care when moving the material around.

Before excavation work obtain excavation permit.

Trenching & Shoring Requirements for Storm Drainage

Check for setting out and mark piping location on ground using pegs confirm the approved drawing.

Excavate trenches under building slab for 300mm cover over the pipe. A minimum of 600mm cover to be provided where pipe may be exposed to heavy overhead traffic.

Shoring of trenches is to be provided if the excavation depth exceeds 1.5m.

Barricade around the area that have been excavated on soft ground.

Keep excavations dry wherever necessary.

Stormwater drainage pipes shall not rest on rock at any point, including joints.

Side fill should be shoveled under the storm drainage pipe to make sure that there are no voids in the side fill.

The haunch areas adjacent to the pipe between the bottom of pipe and its horizontal center-line shall be filled with a clean course-grain materials such as sand, gravel, or soil. Such side fill shall be compacted to provide lateral support for the pipe.

Stormdrain Slope Requirements

Install Sanitary, Vent and Storm drainage piping at the following minimum slopes unless otherwise indicated.

Building Sanitary and Storm Drain: 2 percent downward in the direction of flow for piping NPS 3 (DN 80) and smaller;1 percent downward in direction of flow for piping NPS 4 (DN 100) and larger.

Horizontal Sanitary and Storm Drainage Piping: 2 percent downward in direction of flow.

Vent Piping: 1 percent down toward vertical fixture vent or toward vent stack.

Make changes in direction for Sanitary, Vent and Storm drainage piping using appropriate branches, bends, and long-sweep bends.

Use proper size of standard increasers and reducers if pipes of different sizes are connected.

Reducing size of drainage piping in direction of flow is prohibited.

Install pipes on the concrete pads making sure that they are secured in place and to the required slope.

Follow below details for drainage pipes and fittings as per its application.

Sanitary and Vent piping application guidelines

Storm water Drainage Piping Installation Requirements

Lay buried building storm water drainage piping beginning at low point of each system. Install true to grades and alignment indicated, with unbroken continuity of invert.

Place hub ends of storm water drainage piping upstream.

Install required gaskets according to manufacturer’s written instructions for use of lubricants, cements, and other installation requirements.

Maintain swab in piping and pull past each joint as completed.

Install encasement on storm water drainage piping according to ASTM A 674 or AWWA C105/A 21.5 applicable to Ductile pipe and Cast Iron pipe.

Check pipe straightness and invert level.

Leakage Testing of Stormwater Drainage System

Test drainage and vent piping except outside leaders on completion of roughing-in.

Close openings in piping system and fill with water to point of overflow, but not less than 10-foot head of water (30 kPa).

From 15 minutes before inspection time up to completion of inspection, water level must not drop.

Inspect all the joints for leaks.

Test force main piping on static-water pressure of 50 psig (345 kPa) above operating pressure, without exceeding pressure rating of piping system materials.

See specific specification requirements for the project.

Do not enclose, cover, or put piping into operation until it has been inspected and approved by consultant and authorities having jurisdiction.

Backfilling of storm drainage system

Backfilling of pipe trench for installed underground drainage piping shall be done as below.

Conformance Criteria for Storm Drainage System

The quality personnel on site ensures that the work done conforms to the standard and the required specifications.

Piping materials shall bear label, stamp, or other markings of specified testing agency.

Storm water drainage shall comply with following Local and International Standards.

For solvent cements, adhesive and primers etc. necessary documentation shall be provided indicating that products comply with the health, safety and environmental requirements.

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