Maximum Depth Of The Trench In Pipe Line Project

There are going to be several factors involved in determining the safe load capacity of the pipe:

1. Pipe material type and strength class.

2. Maximum Working (Internal) water pressure, or maximum Hydrostatic Testing Pressure; the maximum of these governs.

3. Maximum Water Temperature.

4. Pipe bedding zone material type, configuration, and trench width at the top of this zone.

5. Pipe zone backfill material type, configuration, and trench width at the top of this zone.

6. pipe trench width, depth, backfill material, and compacted material density above the pipe backfill zone.

7. Maximum Service loads at the surface, such as highway or railway live loads typically.

The Engineer of Record (EOR) should have done the necessary calculations during the project design phase and prior to the Submission of Bidders.

If this is a field change requiring the Contractor install the water main deeper, then it is the Contractor's responsibility to immediately notify the EOR in written for a design recheck to ascertain whether it is safe to do so or not. I have no knowledge of the contents of the Project Manual that you're using there, so I am going on what is normally done here in the USA generally using the ASCE/Engineer's Joint Council boiler plate language, as well as standard practice.

What is the water main material type and strength class? I have no idea what X52 represents as whatever it is we don't use that here. Looking at the 9.5 mm thickness information that you supplied I'm assuming it's a welded steel pipe; probably spiral weld type specifically.

Regardless of the pipe type (be it ductile iron, PVC, Steel, or RCP), there are design handbooks published by the various pipe manufacturing associations, where the design/analysis calculations and load tables are presented.