Sewerage and Sewage Treatment

by Harold E. Babbitt

Work of the Engineer

119. Duties.—The duties of the engineer during construction consist in giving lines and grades; inspecting materials; interpreting the contract, specifications and drawings; making decisions when unexpected conditions are encountered; making estimates of work done; collecting cost data; making progress reports; keeping records; and in guarding the interests of the City.

120. Inspection.—In the inspection of workmanship and materials, the engineer is assisted by a corps of inspectors and assistants who act under his direction. The duties of the inspector are to be present at all times that work is in progress and to act for the engineer in enforcing the terms of the contract, the details of the drawings, and the tests applicable to the workmanship and materials that he is delegated to inspect. He should have a copy of the contract, or that portion of it which pertains to his work, available at all times. He should examine all materials as they are delivered on the job and see that rejected materials are removed at once. An ordinary recourse of some foremen will be to place rejected material to one side until a brief absence of the inspector will present the opportunity for the use of the rejected material. The methods to be followed in the inspection of materials and workmanship should be such as to discover discrepancies between the specifications and the materials delivered or the work done. Other duties of the inspector are: to record the location of house connections or to drive a stake over them for subsequent location by the engineer; to see that plugs are put in the branches left for future house connections; to inspect the workmanship in the making of joints in pipe sewers; to protect the line and grade stakes from displacement; to check the size, depth, and grade of sewers and elevations of special structures, etc.

Dishonest and unscrupulous workmen have many tricks to get by the inspector. These tricks are best learned by experience as no academic list can impress them properly on the memory. The position of the inspector is not always enviable. He must hold the respect of the workmen, of the contractor, and of the engineer. To do this he must not be unreasonable or arbitrary in his decisions, but when a decision is once made he must be firm in following up its enforcement. He must be careful not to give directions whose fulfillment he cannot enforce, nor for which he cannot give adequate reason to his superiors. His integrity must never be questioned. He must not allow himself to become under obligations to the contractor by the acceptance of favors he cannot return except at the expense of his employer, yet at the same time he must not appear priggish by the refusal of all favors or social invitations. In brief he must be friendly without being intimate, independent without being aloof, and firm without being arbitrary.

The engineer must support his inspectors in their decisions or discharge them if he cannot.

121. Interpretation of Contract.—In interpreting the contract, specifications and drawings, the engineer is supposedly an impartial arbiter between the interests of the city and the contractor. His decisions, as to the meaning of the contract, must be founded on his engineering judgment, and should aim to produce the best results without demanding more from the contractor than, in his honest opinion, it is the intention of the contract to demand. However conscientiously he may attempt to remain impartial, and in spite of the honesty of the contractor, his position, as an employee of the city will almost invariably cause him to favor the city in his decisions on close points. The experienced contractor knows this and fixes his bid accordingly, the personality of the engineer sometimes acting as an important factor in the amount of the bid. The situation arises through the character of the contract, and not through a lack of moral integrity on the part of anyone concerned.

122. Unexpected Situations.—When unexpected or uncertain conditions are encountered in construction the engineer should visit the spot at once and should advise or direct, according to the terms of the contract, the procedure to be followed. Such conditions may be the encountering of other pipes, quicksand, rock, etc. Each case is a problem in itself. Water, gas, telephone and electric wire conduits can be moved above or below the sewer being constructed with comparative ease. Other sewers, if smaller, may be permitted to flow temporarily across the line of the sewer under construction and finally discharge into the completed sewer, or one sewer must be made to pass under the other, either as an inverted siphon or by changing the grade of one of the sewers. Rock, or other material for which a special rate of payment is allowed, must be measured as soon as uncovered in order to avoid delaying the work or losing the record of the amount removed. When quicksand is met special precautions must be taken to safeguard the sewer foundation and to insure that the sewer will remain in place until after the backfilling is completed. These precautions are described in Art. 135.

123. Cost Data and Estimates.—Cost account keeping and the making of monthly or other estimates are closely connected. Cost accounts are of value in estimating the amount of work done to date, and in making preliminary estimates of the cost of similar work. Although the engineer is not always required to keep such accounts, they are usually of sufficient value to pay for the labor of keeping them. Under some contracts the contractor’s accounts are open to examination by the engineer. Usually, however, he must depend on reports from the inspectors for information concerning the man-hours required on different pieces of work, and on his own measurements of materials used and his knowledge of their unit costs, in order to make up an estimate of total cost.

The measurement of a completed structure and a summary of the materials used in its construction may act as a check on the use of proper materials as called for in the contract. For example, if it is known that 2,000 bricks are required for the construction of a manhole and if only 15,000 have been used in the construction of ten manholes, it is probable that some or all of the manholes have been skimped. Similar conditions may show in the proportions of concrete, backfilling in tunnels, sheeting to be left in place, etc.

The statement of a few principles of cost accounting, and the illustration of a few blanks in use should be sufficiently suggestive to lead a resourceful engineer in the right direction.[^[79]] Costs should be divided into four general classifications: labor, materials, equipment, and overhead. Labor should be subdivided under its several different classifications arranged in accordance with rates of pay. The number of laborers under each classification and the amount of work done per day should be recorded. Fig. 86 is an example of a form which may be used for such a purpose.

Fig. 86.—Foreman’s Daily Payroll Report.
From Engineering and Contracting, 1907.

Materials may be recorded as they are delivered on the job, as they are used, or in both cases. Measurements are usually easier to make at the time of delivery, but records made at the time materials are used are more serviceable. For example, 100 barrels of cement may be delivered on a job in November, 50 of them are used before the job freezes up and the other 50 are held over until spring. It would be misleading to charge 100 barrels used in November. Fig. 87 is a form in use for an inspector’s report on materials. The total cost must be made up in the office from these records and a knowledge of unit costs.

Fig. 87.—Foreman’s Daily Material Report.
From Engineering and Contracting, 1907.

Equipment consists of tools, animals, machinery, and apparatus used in construction. Only equipment that is actually used should be charged to the job and a credit should be made at the completion of the job for the fair value of the equipment remaining after the completion of the work.

Overhead charges include the expense of the office force, superintendence, and miscellaneous items such as insurance, rent, transportation, etc., which cannot be charged to any particular portion of the work but are equally applicable to all portions. It happens frequently that many jobs are handled in the same main office. The division of overhead becomes more difficult and is frequently arranged on an arbitrary basis, e.g., each job may be charged the proportion of overhead that its contract price bears to the total contract prices being performed under that office. This rule may be modified when it becomes evident that some job is taking distinctly more than its share of the overhead.

Estimates of work done in any period can be made with the above data in hand by subtracting the total costs of the work up to the beginning of the period from the total costs up to the end of the period. Fig. 88 shows a sample blank from the final estimate sheets used at Scarsdale, N. Y.

124. Progress Reports.[^[80]]—These are kept by the engineer in order that he may see that the work is progressing as called for in the contract, and any portion which is lagging behind without reason may be pushed. Such reports are most useful when the information is expressed graphically, as the eye quickly catches points where the work is falling behind schedule.

125. Records.—The contract drawings are supposed to show exactly where and how construction is to be done. Due to unexpected contingencies changes occur, of which a record should be made and preserved. These records may be kept in a form similar to the contract drawings, or if the changes are not extensive, they can be recorded on the original contract drawings. The location of house and other connections should be recorded in a separate note book available for immediate consultation. The engineer should keep a diary of the work in which are recorded events of ordinary routine as well as those of special interest and importance. This diary should be illustrated by photographs showing the condition of the streets before and after construction, methods of construction, accidents, etc. Such accounts are of great value in defending subsequent litigation and their existence sometimes prevents litigation. A contractor may wait a year or so after the completion of a piece of work until the engineer and other city officials have broken their connection with the city. Suit is then brought against the city and unless good records are available the administration may be forced to buy the claimant off or may elect to enter court, only to be beaten.

Fig. 88.—Samples of Cost Record Forms.
From Engineering and Contracting, 1909.