Water Line Replacement

Often cities are faced with rehabilitation and replacement projects. Planning the project can include traffic control, material and equipment cost, manpower, permits, etc., and of course, math. As most operators are slowly finding out, math is still an element that they cannot avoid when it comes to being an operator. Even when one does not realize it, math is a vital part of most applications in the operator community. So keep the formula sheet handy even after you take the test. The following scenario shows only some of the many costs associated with this type of infrastructure repair or replacement. Make sure you don’t add more accidental cost to a project.


Part One

The city has decided to take on the project of replacing the water line that runs along the bypass around town. This will entail digging up and replacing 4.4 miles of 18-inch line that is buried, on average 5 feet deep. The trench boxes that the city owns are 5 feet wide and 8 feet long, so assume the trench has to be 5 feet wide and 5 feet deep and 4.4 miles long. How many cubic yards (1 cubic yard = 27 cubic feet) of soil have to be removed to replace this line?

Part Two

In the specifications, the engineer specified 6 inches of bedding in the bottom of the ditch to protect the pipe. How many 20 yd3 dump truck loads will it take to provide the bedding for the replacement project and at a $52.50 per load delivery fee, what will it cost?

To find out how to solve this problem, click here.

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