Question

This problem involves building an earth dam using 22,000, 000 cubic yards of clay and 4,000,000 cubic yards of clean sand all compacted to 95% of maximum density based on ASTM D698. The sand and clay are placed in separate sections on the natural ground level. Below ground level 30 feet of wet sand needs to be removed and replaced with compacted clay to a depth of 30 feet with an excavation width averaging 100 feet. The clay will obtained three miles from the project at an elevation 100 feet below the project site that is only accessed using a dirt road. The clay is very hard.The sand is available paved road, 17 miles away, 300 feet below the project site. The project needs to be completed in 800 days. Determine the amount and types of equipment you feel should be used on this project. Assume the dam is 200 feet high above the natural ground level and has a 20 foot wide top width and 2:1(H:V) side slopes.

Answer 1

Solution) Given

Clay = 22,000,000 yd^{​​​​​3}​

Excavation of wet sand quantity = 30 x 100 x 10 = 30000 ft^{​​​​​3}​

As to balance we have to fill the same quantity as we excavated which is filled by 50% sand and 50% clay

Consider capacity of one vehicle = 150ft³

​​​​​ Thus number of trips to be done is equal to 3000000/150 = 2000 trips of vehicle shall be done

As we have to arrange the one vehicle for transportation of clay and sand

Only daily basis we can complete the fillng work within 800 days

One excavator can excavate 250ft in one day = 3000000/250= 1200

If we have to complete the excavation in 800 days = 1200/800= 1.5 approximately equal to 2

Thus we need 2 number of excavators for excavation and same excavator for sand and clay.