For Steam Generation, Compressed Air Distribution A Central Station Comprising

Items 1 to 7, of proper capacity (9) Steam piping to compressors

(10) Compressors including foundations

(11) House for compressors

(12) Cooling and condensing water supply

(13) Air receivers

(14) Air distribution piping

For Steam Generation, Electric Distribution

Items 1 to 7, house for engines or turbines

(15) Steam piping to engines or turbines

(16) Engines or turbines, including foundations Item 12

(17) Generators

(18) Switchboard

If distance is large

(19) Step-up transformers

(20) Transmission line

For Steam Generation, Electric Distribution

(21) Step-down transformers or

(22) Motor-generator

(23) Sub-station building

(24) Switchboard

(25) Distribution wiring

(26) Motor

(27) Compressor and item 14

For Hydro-Electric Generation, Electric Distribution

(28) Diversion dam

(29) Head gates

(30) Canal

(31) Flume (32) Forebay

(33) Screens

(34) Penstock

(35) Water-wheel including setting

(36) Water-wheel governor

Item 11 for water-wheels, generators, etc. Items 17 to 27 inclusive

For Purchased Electric Power

Items 20 to 27 inclusive.

In addition to the above it may be desirable to build a railroad to the work, for which estimate ties, track and fastenings, locomotives, cars, etc. The construction of such a road is here considered under Erection of Plant.

The main items of plant are merely suggested, others may be necessary on any particular piece of work. Selection of the proper kind and amount of plant can be definitely made only after a rather thorough study of the situation, including the amount and character of all the materials to be excavated, handled or disposed of; stream flow and measures for handling water; price and character of labor; climate; desired rate of progress, etc. For certain of the processes (as pumping) one cannot predict accurately the amount of plant required. It is well to provide largely, even an amount that will certainly meet any contingency, as carrying excess plant may be vastly cheaper than delay from insufficient plant. For the same reason duplicate or repair parts should be provided, especially for any items of plant whose breakdown would seriously affect the progress of the work.

Prices are practically never mentioned in any machinery or equipment catalogues. The estimator should aim to keep generally informed as to such prices, sufficiently so to be able to form an approximate estimate. Freight rates upon A, plant, B, expendible material, and C, material entering the work, should be a matter of inquiry at the time the site is being examined. In addition to the rates the total quantities and weights should be estimated as closely as may be. The haul from railroad to dam site may be of as much or more importance than the railroad freight. To settle properly the question involves estimates of cost of haul per ton-mile under the alternate or several possible methods. These estimates taken in connection with the total weights involved will indicate the justifiable expenditure for building or improving highways and bridges or for building and equipping a railroad. (See pages 127 and 128.) Broadly speaking any division between plant and erection of plant is largely fictitious, for an expenditure under head of erection is really a plant charge. The distinction is only made here in order that the items may be listed so that none will be overlooked, and to point the difference between plant which has a salvage value, and plant which has none.

Erection labor includes labor on highway or railroad to facilitate haul, building machinery foundations and housing, assembling the machinery and putting into running order, building cableway towers, grading for their foundations and laying track if they are traversing cableways, erecting camp and office buildings, stables, cement storage, sand and crushed stone bins, etc.

Erection materials would include cement for foundations, lumber, hardware, brick, etc., for the various buildings, or for culverts and bridges on the lines of transportation.

If, as is often the case, the contractor must construct the cofferdams and other temporary work for the diversion and handling of water, and does not directly receive pay as an item in the contract, such works should be properly estimated as plant, or rather under the subdivision of erection of plant. Such estimate involves the determination of a scheme of diversion and a more or less definite plan for adequate works, unless both are specified. In any case it calls for a determination of quantities of materials required as piles, wood or metal sheet piling, lumber, hardware, cement, etc., and an estimate of the labor of building, including the necessary earth or rock excavation, embankment, etc. Whether such work and the expenditure on it is classified as plant or as an item of the contract is immaterial and only a matter of book-keeping; the item itself, it need not be pointed out, is of the utmost importance. It requires the ripest judgment as to design, plant and methods, and is usually after all the item principally in mind when estimating the amount which it is desirable to allow for contingencies.

Items A-5 and A-6 require no explanation; the information upon which they are based has been acquired and used for items A-2 and A-3. The destination and disposition of plant after a job is often an uncertainty, and in any case the transportation expense may be approximated closely enough.

Wherever and however disposed of item A-7, salvage, means the value of certain items of plant at some point of demand or place where they can be used on other work by the same or another contractor. The job under consideration must be charged with the cost of dismantling and transportation to some point where it becomes chargeable to another job. Where as is often the case the plant is to be used by the same contractor on other work the division of charges may be more or less arbitrary, in other words, a matter of book-keeping between two contracts and based upon a more or less casual valuation or estimate of depreciation. Where the plant is sold to another party the matter is not so simple. It will then depend, somewhat at least, upon cost to the purchaser of new or other second-hand plant at the point where he desires to use it. Entering into the problem then is the location of the second point of use as well as of the first point in their relation to centers of supply; also the amount and location of other secondhand plants which may be released at about the same time. It is quite possible if much work is in contemplation or is being prosecuted in a locality near the work under consideration and at the same time remote from a center of supply, that the salvage value will be a large per cent, of the original cost.