310 THE IMPROVEMI-.XT OF RIVERS. 



timber." The remaining materials used shall be furnished by the contractor at his 

 own cost and covered by his price for " Coffer-dam timber." 



17. Ownership. The payments made for the different parts of the coffer-dam 

 and cement-testing shed and the cement storehouse shall cover the entire cost thereof 

 to the United States, and by virtue thereof- they shall become the property of the 

 United States. 



18. Floods. Whenever the river rises to a stage which, in the opinion of the Engi- 

 neer, endangers the safety of the coffer-dam, the inclosure shall be filled through the 

 sluiceways. The cost of all pumping shall be borne by the contractor. 



EXCAVATION, EMBANKMENT, AND PAVING. 



19. Clearing Site. The removal from the site for the lock, cribs, paving, and coffer- 

 dam, before and during construction of all trees, bushes, stumps, logs, roots, drift, and 

 other rubbish, shall be performed by the contractor at his own expense, and the cost 

 shall be included in the price paid for Excavation. 



20. Classification.* Excavation will be classified as " Rock Excavation," " Earth Ex- 

 cavation," and " Deposit, " and will all be measured by contents in place, before removal. 

 Rock which cannot be loosened by pick or bar, but requires blasting for its removal, and 

 also all boulders of a volume greater than 9 cubic feet, will be classified as " Rock Exca- 

 vation." Rock that can be loosened by pick or bar, and boulders having a volume of 9 

 cubic feet or less, and all other materials of whatever nature, except "Deposit," will 

 be classified as "Earth Excavation." Material washed or left in the coffer-dam 

 inclosures by floods, except that which slides in from the bank, will be classified as 

 " Deposit," and the price paid for " Deposit" shall cover the cost of all necessary cleaning 

 and scrubbing. The Engineer will give directions as to what part or how much of such 

 deposit shall be removed. In general, deposit will not be ordered for removal, unless 

 it interfere with the work, nor will any payment be made for deposit removed by the 

 contractor without orders from the Engineer. The deposit or earth excavation which 

 may be removed by the contractor in tearing out the coffer-dam will not be estimated 

 for payment. No payment will be made for removing material washed into the inclos- 

 ures from the coffer-dam, or from any dump made by the contractor on or above the 

 work, nor for duplicating foundation excavation in cases where the hole has filled again 

 because the masonry construction did not promptly follow the excavation, of which 

 lack of promptness the Engineer shall be the judge. The prices paid for all excavation 

 shall include the removal of the material to its place of deposit. 



* The classification of " Deposit," especially where the banks are soft, results usually in uncertainty and 

 dispute as to what part of the excavation actually was deposit and what part earth For this reason it 

 will be found advisable, except in a few rare cases, to omit it entirely, and to include it in " Earth Excavation." 

 For similar reasons it is usually best to omit "Loose Rock" classification, as where the stones are imbedded 

 in earth, it is usually impossible to obtain an accurate estimate for each material. 



