CHAPTER XII.

OVERSIGHT AND MEASUREMENT OF WORK.

ART. 65.

INSPECTION OF WORK.

THE specifications are practically the instructions to the contractor as to the way in which the sewerage system is to be built, the lines, grades, and dimensions being given by the engineer, chief or assistant. If the contractor were left unwatched to carry out these instructions it would be impossible to know whether he had done so or not, since only the inside of the sewer can be examined, and this only with difficulty. And if it were found, after the completion of the work, that it had been improperly built or of poor material, even though the contractor could be compelled to replace it with satisfactory work, the delay and inconvenience of this might better be avoided by proper oversight during construction. It is advisable, therefore, that a competent inspector be constantly on hand when any construction is progressing. This is not necessary during excavation, but even this should be looked after at least once a day, that any unforeseen underground condition which may modify the plans may be noted, and in general to ascertain that the contractor is obtaining the proper width of trench, is not interfering unnecessarily with private drains, water- or gas-pipes, and is in general following the directions for trenching, blasting, etc.

For this oversight it will usually be necessary to have an inspector for each set of pipe-layers and of masons. But if

only one or two trenches are being worked at a time the instrument-man may also be inspector. The omissions and poor work which may be accepted from the contractor if such inspection is not constantly made may be seen from a statement of the inspector's duty.

The inspector should be on hand before work is begun at morning and noon to see that no mortar left from the previous day is worked over, that new mortar is properly proportioned and mixed, and to examine grade-lines or -stakes. In the case of pipe sewers he should examine the inside of the sewer near the end and see that any stones, dirt, or other matter which may be there be removed before the laying begins. He should also examine the one or two cemented joints nearest the end, and if they are not sound the pipe should be removed and relayed. In the case of brick sewers he should examine the toothing at the end of the brick-work and have removed any loose brick and all mortar and dirt that may be lodged there.

He should continually keep an eye upon material and workmanship, examining each pipe before it is lowered into the trench, each load of brick and of sand as they are brought 'upon the ground, each barrel or bag of cement to see that it bears the engineer's mark or is of the required make and that it is not caked by moisture. He should see that the proper proportions of cement and sand are used for the mortar, and that no mortar partially set is retempered and used.

On brick sewers he should see that each templet used is one approved by the engineer and that it is set to the proper grade and line, that the brick are laid to line and in accordance with the specifications, that slants or other branches are set where needed, and he should keep an accurate account of these, their size and length, and mark the position of each by a stake driven in the bank directly over it for the information of the engineer. He should see that the arch-centre is solid

and does not spring under the brick-work, and that it is not drawn too soon.

On pipe sewers he should see that each pipe is laid to grade and line by the use of the grade-rod and a plumb-bob in connection with the grade-cord, that each pipe is pushed "home," each joint properly cemented and the swab or piston in the sewer pulled forward, and that the back-filling is properly placed and tamped around the pipe. He should see that house-branches are placed where directed, that covers are cemented in each one (about this he is sometimes careless, to the great detriment of the sewer), and should drive a stake in the bank directly over each.

He should keep a record of all extra work, or work, such as foundations or sheathing left in the trench, which cannot be measured after the completion of the sewer.

If the ground is wet he should see that no water flows over the brick-work or through the pipe, except as permitted by the engineer. In general he should be thoroughly familiar with the specifications and have a copy constantly on the work, and see to their enforcement, reporting to the engineer any difficulty in obtaining this.

He should not be permitted to be in any way indebted to, or under the influence and power of, the contractor, and should receive orders from the engineer only.

He should be a man with some experience in the character of work he is inspecting, sober, and having the respect of the contractor and workmen.

ART. 66. DUTIES OF THE ENGINEER.

The engineer should keep constantly in touch with the work, visiting each point at least once a day, and giving necessary instructions to the contractor and inspector, as well as giving and testing line and grade. If he has many

inspectors on work under his charge they should be required to report at the engineer's office after each day's work the amount done and return a detailed statement of any extra work, asking instructions on any points concerning which they are in doubt. The daily reports may be made in writing upon blanks furnished to the inspectors for this purpose.

The engineer must see that each inspector is performing his duty, and if necessary enforce instructions given by him to the contractor. He must inspect all material to be used, where this is possible, or give the inspector full instructions on this point where it is not. It is well to mark each accepted barrel or bag of cement; to inspect the pipe after it is delivered upon the street, but well in advance of the laying, seeing that all defective pipe is removed; also to inspect and weigh all iron-work before it is used.

The engineer must decide where and how much sheathing shall be left in the trench, making a note at the time of its exact location and length, must decide as to the classification of the material being excavated, and must measure promptly all material classed as rock. He should each day take measurements necessary to locate the house-branches as indicated by the inspectors' stakes. It is well to measure each stretch of sewer, each manhole and other appurtenance as soon as completed.

The engineer should see that the contractor respects the rights of property-owners and keeps the streets and sidewalks open where possible, that the laborers are efficient and, where necessary, skilled in the work to which they are assigned, and that they create no disturbance along the streets in any way for which the contractor is responsible. He should compel the contractor to work with sufficient force and in such a manner as will lead to the completion of the work in the specified time, to place such shoring and sheathing as may be necessary to prevent any accidents to property or lives or to

the sewer, to provide pumps in sufficient number and of ample size to handle all ground-water, and to use excavatingmachinery where necessary. In general he should see that the work is carried on by proper methods, with proper materials, with a force and a plant satisfactory in both character and extent, and that the inspector enforces his directions as to details.

The specifications should state in what way the measurements shall be taken for each description of work or material. The measurements so made for the final estimate (which is the name customarily given to the measurements and calculations on which is based the final payment for a piece of work) should be accurately and carefully taken and checked at least once, as should be the calculations based thereon. The engineer should be able to swear upon the witness-stand, as he may be called upon to do, that the final estimate is a truthful and correct statement of the work actually done. Quantities given in this estimate should be stated in the units used in bidding for the work.

Measurement of the sewer laid is usually made from centre to centre of manholes, flush-tanks, etc., not horizontally, but parallel to the sewer (the surface of the street being practically this in most cases), no deduction being made for branch specials or the lengths of manholes. Payment is sometimes made uniformly for all depths of sewer, sometimes varying with varying depths. The latter seems the fairer way, particularly where some lines contracted for may be omitted or new ones added. Usually no changes in price are made for less differences in depth than two feet, the measurement being made from the surface to the under side of sewer or of foundation-platform. These depths are ascertained from the