(a) Trenching. The length, width and location of the trench , also the manner in which the work is done, shall be under the control of the street commissioner. Every precaution shall be taken to safeguard the work and to inconvenience the public as little as possible.
(1) The permittee shall carefully remove the paving material and base course in such a manner that adjacent base and paving is not damaged. Damaged paving, base or both will be removed and replaced as required. Excavated material shall be placed so as not to obstruct gutters or drains and in such manner as will cause minimum inconvenience to the public. If necessary, temporary covers for gutters shall be installed to insure adequate drainage. In special cases it may be necessary to haul excavated material from the street.
(2) Trenches must be properly sheeted and braced, where necessary, to prevent caving, slipping or cracking of sides. Sheeting and bracing used to support the sides of the trench, shall be carefully removed as the backfilling of the trench progresses, but if considered necessary by the Street Commissioner for the protection of the banks , the sheeting and bracing shall be left in the trench. Where, in excavating the trench or laying the pipe and appurtenances, the pavement along the sides of the trench is, or becomes, undermined and unsupported, the permittee shall, at his own cost and expense, break down and remove such pavement and the foundation thereof, remove all loose earth and replace with earth properly compacted in the manner provided in subsection (c) of this section.
(b) Tunnelling. Tunnelling is often necessary where a pipe or conduit passes under the curb, street, railway tracks or other conduits. The permittee, however, shall not do any tunnelling except when required by or given permission by the Street Commissioner. Where the tunnelling has been done, the permittee shall bed the conduit being installed in fine material to a height of one foot above top thereof. This fine material shall be wetted and tamped under, around and over the pipe of conduit in the most thorough and careful manner. The balance of the space from top of this filling to the roof of the tunnel shall be completely filled with 1: 3: 5 concrete of suitable consistency, thoroughly tamped to fill the entire space, and a rigid support shall be afforded
for the tunnel roof for its entire area.
(1) In the installation of small service pipes, it is suggested that the pipe be jacked through and under car tracks, curbs, etc. , or that a hole be bored of sufficient size for the pipe.
(2) Whenever the trench crosses under any railroad, a permit from the railroad must be obtained prior to application for the street opening permit.
(3) The permittee shall use all proper precautions to protect persons from injury. Proper guards shall be placed along the line of the trench and red lights placed to adequately protect traffic.
(c) Backfilling. It is very important that the street paving be restored as quickly as is possible after the backfilling has been completed. It is, therefor, essential that the backfilling be thoroughly compacted to prevent subsequent settlement. Advance notice of the time when the backfilling is to be done may be required, so as to permit the inspection of this work.
(1) After the pipes or other conduits have been laid, the bottom of the trench shall be filled with fine selected material and tamped with proper tools to insure the complete filling of the space at the bottom and sides of the pipes or conduits. The material used for filling to a height of not less than six inches above the top of structure must be free from rock and must be thoroughly tamped to prevent any settlement of the pipe. The trench shall then be filled to the bottom of the paving base in six-inch layers thoroughly compacted. Frozen earth or other material which cannot be properly compacted shall not be used for backfilling under any circumstances. The permittee shall remove from the site any excavated material unsuitable for backfilling and replace with suitable material. Temporary restoration will then be made as provided in Section 905.06.
(2) If the trench is sheeted, the sheeting shall not be removed until sufficient backfill has been placed to provide lateral support to prevent caving of the trench. All voids left by the removal of sheeting must be thoroughly filled with suitable material. If it is necessary to leave the sheeting in the trench, it must be allowed to extend above the subgrade of the proposed restoration.