(i) The additional cost. The Contractor naturally adds the estimated expense of maintenance to his bid. Should the Owner assume the responsibility of maintenance he might be able to make his own repairs at a less expense.

(ii) The difficulty of accurately defining the term “maintenance." Shall the work appear as good as new at the end of the maintenance period? If not, how much wear shall be considered reasonable? Many foolish requirements, impossible of enforcement, have found their way into specifications in the attempt to set an arbitrary limit to the amount of ordinary wear.

(iii) The annoyance of forcing the Contractor to make the repairs. A dishonest Contractor has many excuses to offer in the effort to shirk this responsibility.

As applied to pavements, a most perplexing situation arises when portions of the pavement are necessarily disturbed by others (as for water or sewer connections). Another bone of contention is likely to appear where the amount of vehicular traffic suddenly increases during the period of guarantee, as in the case of a street which changes from a residence to a business street.

The period of maintenance of pavements has been steadily decreasing. Formerly ten years was a common requirement, now periods of from one to five years are the rule where any guarantee at all is required. Under most conditions better results can perhaps be attained at less expense without the maintenance clause at least in the case of pavements.

(the

(4) The Contractor agrees to make all the needed repairs
on the said work during a period of one year after its
final completion and he agrees that
Owner)
is authorized to retain out of the
moneys payable to the Contractor under this agree-
ment the sum of two (2) per cent of the amount of the
contract and to expend the same or as much thereof
as may be required in making the aforesaid repairs to
the satisfaction of the Engineer if within ten days
after the delivery or mailing of a notice in writing to
the Contractor or his agents he or they shall neglect to

make the aforesaid needed repairs; provided, however,
that in case of an emergency where in the opinion of
the Engineer delay would cause serious loss or damage
(the Owner)
may make repairs
without previous notice and at the expense of the Con-

tractor.

(B) The Contractor hereby further agrees that all the structures built by him under this contract shall be kept in good and satisfactory condition for the period of one year after the completion of the work to be done under this contract. Should any defects in the work or structures become evident before the expiration of the above guarantee the Contractor shall within five days from the date of the receiving of personal notice or the mailing of a notice by the Engineer to the Contractor proceed to remedy such defects of whatever nature or extent or whenever and wherever found in a proper manner and to the satisfaction of the Engineer and at the expense of the Contractor. In the event of the failure of the Contractor to begin such repairs within the five days above noted

that

(the Owner) .. shall have the right to make
'such repairs and the cost thereof shall be paid by the
Contractor; and it is expressly agreed by and between
the Contractor and ...... (the Owner) ...
the surety bond attached to and made a part of this
contract shall be in full force until the expiration of
one year from the date of the payment of the final
amount due the Contractor for work done and materials
furnished under this contract.

CHAPTER XII

SPECIFIC CLAUSES

In the preparation of the specific or technical clauses, it is well to observe a few simple but important directions; in addition to those given in Chapter V, which the student should review at this point. For the distinction between specific and general clauses see Chapter II.

60. Grouping. - It is much easier to refer to these clauses as a whole if they be segregated from the general clauses and preceded by a proper heading.

61. Sequence. As far as is practicable, they should be arranged, for convenience of reference, in chronological sequence (the order in which it is natural to expect the work to be done). This does not, of course, restrict the Contractor to the order observed in the specifications. In some specifications the clauses relating to materials are further segregated from those referring to workmanship.

62. Indefinite Terms. - Descriptive terms or units, unless perfectly definite, should be studiously qualified so as to make them definite.

(a) For the measurement of masonry, units such as cubic feet or cubic yards would appear to be, and in the case of many engineering structures are, perfectly definite. Certain well established trade rules, varying somewhat locally, affect the measurement of masonry in buildings. Such rules not infrequently provide for the double measurement of corners (or returns), and for the complete or partial disregard of openings (such as doors and windows).

Building stone is frequently required to be furnished by the cubic unit. In such cases it should be made clear as to whether

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the measurement is to be based on the volume of each separate stone, or of a heap of stone, or of the finished wall.*

(b) As applied to earth, the handling of some of which is necessitated in almost every engineering project, the term "cubic yard" needs qualification, for earth may be and is measured in one of three ways:

(i) Before it has been disturbed (in situ), as in railroad grading and similar work.†

(ii) In transit, as in a scow on dredging contracts, or in a cart.

(iii) In its final resting place, as in certain kinds of filling, for example the reclaiming of marsh land by the hydraulic process. In such cases the date of measurement and other points may need careful attention in the specifications, as some material continues to change volume for a long period of time.

(c) The lack of a proper differentiation of earth and rock in the specifications has occasioned a vast amount of unpleasant feeling and of litigation in connection with contract work of a certain character. Geologists make no real distinction between the two. In common parlance earth is soft and rock hard, but these adjectives lose much of their force where there is an almost imperceptible gradation between the two materials in situ. Three methods of classification follow:

(i) The distinction most commonly made is that anything requiring blasting for its removal will be estimated as rock. Not infrequently boulders of a certain minimum volume, and tree stumps, both of which it might be possible — though perhaps not economical to remove in some other way, are

* Such units as "perch" should never be used by Engineers. A perch of masonry properly contains 24 cubic feet (161⁄2 by 11⁄2 by 1). In country districts where it is still in use as a unit a perch of masonry is variously assumed to contain anywhere from 22 to 25 cubic feet of stone.

Of interest in this connection is a publication of the Bureau of Standards, Department of Commerce and Labor, Washington, D. C., 1912, entitled "State and National Laws Concerning the Weights and Measures of the United States." †The measurement of rock excavation is almost invariably made in situ.

classed as rock. In many instances "loose rock" is classified separately.*

"No soft, loose or broken rock, impacted boulders or hardpan, but only such solid rock as may be approved by the Engineer in advance as requiring blasting for its removal, and boulders of one half (1) cubic yard or more found in and removed from the excavation, are to be considered as rock excavation."

(ii) Another plan for differentiation is based on the possibility of removing the material with a plow.

"Dry excavation of rock will include the removal of all ledge rock and hardpan which, in the opinion of the resident Engineer, cannot be plowed, and all boulders measuring one-half a cubic yard or more." (N. Y. State Canals, 1904.)

(iii) A recent specification fixes the dividing line between earth and rock at three on the scale of mineral hardness (sometimes called the "Mohs" scale). The student should point out two difficulties apparently involved.

"Whenever the word 'rock' occurs in these specifications, it shall be interpreted to mean any material geologically in place and of a hardness when first exposed of three or greater in the scale of mineral hardness, which corresponds to the hardness of the transparent variety of calcite. Other material will not be classed as rock, although it may be more economical to remove the same by blasting." (Chicago Sewers, 1911.)

The student should note that certain materials, such as hardpan or quicksand, while properly classed as earth, may in reality be more expensive to excavate than some grades of rock, and further, that it is sometimes advisable to classify earth or rock according to depth of excavation, length of haul, number of times it must be handled, amount of contained moisture, or in other respects. While it is practically impossible to draft a clause covering earth and rock which will be applicable to all local conditions geological and otherwise, painstaking definition in the specifications, and provision for special prices will lead to mutual understanding and often to lower bids. On large and important excavation contracts the expedient of using, as illustrations, samples obtained from borings may

* Solid rock has been defined in some specifications as rock which rings when struck with a light hammer.