APPENDIX B. 3 n 



21. Removal of Bed-rock. In removing bed-rock by blasting care shall be used not 

 to shatter the rock where any superstructure is to be laid upon it. No heavy charges 

 shall be exploded in the bed-rock within 2 feet of the final surface, nor within 10 feet 

 of any masonry ; the final portions shall be removed by light blasts and picks and bars. 



22. Extent of Excavation. Preliminary lines, slopes, and grades will be given by 

 the Engineer for all excavation, but they may be changed by him from time to time, 

 as the nature of the work may demand; these lines, slopes, and grades will be the 

 limits beyond which the contractor must not go. It must be understood, however, 

 that the excavation will not necessarily be made to these limits, unless it is specifically 

 ordered so by the Engineer, and that the slope of any excavation shall be as much 

 steeper than the marked slope as the material will stand. The contractor will be paid 

 only for the material actually removed. Any slip occurring through the negligence, 

 fault, or delay of the contractor (of which negligence, fault, or delay the Engineer 

 shall be the judge) must be removed and back-filled by him at his own expense if so 

 ordered by the Engineer; but any slip occurring without negligence, fault, or delay on 

 the part of the contractor will be estimated for payment if ordered by the Engineer to 

 be removed. Any material excavated in the absence of, or in disregard of instruc- 

 tions from, the Engineer, or removed from outside of the lines, slopes, or grades given 

 by him, will not be paid for, and must be back-filled by the contractor at his own 

 expense, if so ordered. 



In case any of the material to be excavated is removed and carried away by floods 

 during the execution of the contract, the contractor will receive pay only for so much 

 of it as may have been included in the limits of the latest slopes given him by the Engi- 

 neer, except that if any of the space is filled up again, or partly filled up by deposit 

 from the river, the contractor will not be paid both for the original material and for 

 that deposited by the river in its place, but only for so much of that deposited as 

 may be ordered to be removed. 



The extent to which the contractor will be allowed to remove the bank inside the 

 coffer-dam by dredging, and the time for commencing such work, will be subject to 

 the orders of the Engineer, and if work be started too late in the season to permit 

 laying sufficient masonry no dredging will be permitted. If it be started in time to 

 build up most of the foundation, dredging will be permitted for so much of the founda- 

 tions as may be deemed advisable, commencing with the river-wall. Should the con- 

 tractor desire to tear out a certain portion of the coffer-dam in the following season, 

 subject to the approval of the Engineer, in order to continue dredging, he will be 

 allowed to do so, but such tearing-out, and the rebuilding, refilling, and backing of the 

 coffer-dam to the original lines shall be at his own expense. 



No dredging for the land- wall will be permitted beyond a line distant 10 feet from 

 the chamber face of that wall, measured toward the bank. The remainder of th- 

 excavation must be done in the dry, after the coffer-dam has been pumped out. 



Material in the chamber and entrances will not be removed except as may be 



