This section is from the book "A Treatise On Architecture And Building Construction Vol4: Plumbing And Gas-Fitting, Heating And Ventilation, Painting And Decorating, Estimating And Calculating Quantities", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
Matters To Be Considered. Excavation is generally measured by the cubic yard, although, in a few localities, measurement by the perch is still in use. If the latter method is adopted, it should be stated just what is meant by a perch, as this varies considerably in different parts of the country.
Before fixing the price for excavation, it is advisable to investigate the character of the soil, by making boring tests. Where there is rock excavation which requires to be blasted, a special price should be given in the estimate. If the ground is wet, rendering pumping necessary, provision should be made for the cost of the extra labor needed. The disposition to be made of the excavated material should also be considered, as, if it must be hauled a long distance, the cost will be much greater than if the soil may be wasted near by. To aid in estimating the actual cost, it is convenient and approximately correct to consider 1 cubic yard of ordinary earth as a load for an ordinary two-horse wagon.
In making calculations of the amount of material to be removed, care must be taken to note the existing levels of the ground and those required by the drawings. The excavation should be figured (and made) at least 1 foot greater than the size of the foundation, so as to provide room for setting the masonry, pointing, etc.
Excavation for pipes, drains, etc. should be at least 9 inches wider than the diameter of the pipe to be laid therein. If the soil in which the excavation is made is of a loose and sandy nature, likely to crumble and slide, a slope, say of 3 inches horizontal to 1 foot vertical, should be allowed on both sides of the trenches. If the latter are of considerable depth, it is sometimes necessary to curb or shore up the sides, in which case an allowance should be made in the estimate for the lumber required.
If piles are required, figure them at so much per lineal foot, driven.