DRAINAGE METHODS FOR COUNTY ROADS. 83 
All trees, stumps, and roots within the limit of the improvement shall be 
grubbed up so that no part of them shall be within 6 inches of the surface 
of the ground or within 18 inches of the surface of the subgrade. 
Embankments shall be formed of good, sound earth and carried up full width. 
The earth shall be deposited in layers not more than 1 foot in thickness, and 
each layer shall be rolled or otherwise suitably compacted by distributing 
traffic uniformly over the surface until thoroughly compacted. 
All existing slopes and surfaces of embankments shall be plowed or scarified 
where additional fill is to be made, in order that the old and new material 
may bond together. When sufficient material is not available within the fence 
lines to complete the embankments, suitable borrow pits, from which the con- 
tractor must obtain the necessary material, will be designated by the engineer. 
If there is more material taken from the cuts than is required to construct the 
embankments as shown on the plans, the excess material shall be used in 
uniformly widening the embankments or shall be deposited where the engi- 
neer may direct. Wherever embankments are formed of stone the material 
shall be carefully placed, so that all large stones shall be well distributed and 
the interstices shall be completely filled with smaller stone, earth, sand, or 
gravel, so as to form a solid embankment. 
During the work of grading, the sides of the road shall be kept lower than 
the center and the surface maintained in condition for adequate drainage. 
The grading of any portion of the road shall be complete before any sur- 
facing material is placed on that portion ; and where the plans do not call for 
any substantial change in the grade of any existing section of the road the 
surface shall be completely scarified to a depth of 3 inches or more before the 
subgrade is prepared. 
SUBGRADE. 
The subgrade, or that portion of the road upon which the roadway is to be 
constructed shall consist of good, sound earth brought to the proper elevation, 
alinement, and cross section, and shall be rolled until firm and hard. The 
rolling shall be done with a power roller, weighing not less than 10 tons and 
not more than 15 tons. Should earth be encountered which will not compact by 
rolling, so as to be firm and hard, it shall be removed and suitable material 
put in its place, and that portion of the subgrade shall be again rolled. When 
the rolling is completed the surface of the subgrade shall conform to the cross 
section shown on the plans, and shall have the proper elevation and aline- 
ment, and shall be so maintained until it is covered by the foundation or road 
crust. 
CRUSHED-STONE FOUNDATION. 
Where a crushed-stone foundation is called for on the plans it shall be con- 
structed after the curbs are set and in two courses of such thickness that the 
finished foundation will have the required depth shown on the plans. 
The first course of stone shall consist of a single layer of No. 1 stone spread 
uniformly to a depth of not more than 6 inches before compacting. The stone 
shall be spread by hand from dumping boards or from dump wagons of a type 
that will distribute each load of stone evenly over that part of the subgrade to 
be covered by the load. 
After the crushed stone of the first course has been spread to the required 
depth, it shall be rolled until it is thoroughly compacted and firm with a three- 
wheeled power roller weighing not less than 10 tons and not "more than 15 tons. 
The rolling shall begin at the curbs and progress gradually toward the crown. 
All irregularities and depressions that may develop shall be immediately cor- 
