(A) Trench dimensions. The minimum width of the trench shall be equal to the outside diameter of the pipe at the joint plus eight inches for unsheeted trench, or 12 inches for the sheeted trench, and the maximum width of trench, measured at the top of the pipe, shall not exceed the outside pipe diameter plus two feet, unless otherwise shown on the drawing details, or approved by the city.
(B) Utility bedding.
(1) Class B (minimum utility bedding). The bottom of the trench shall be shaped to provide a firm bedding for the pipe. The pipe shall be firmly bedded in undisturbed firm soil, or hand shaped unyielding material. The bedding shall be shaped so that the pipe will be continuous therewith for its full length.
(2) Class A (special utility bedding). Should special bedding be required due to depth of cover, impact loadings, or other conditions, "Class A" bedding shall be installed.
(C) Unsuitable material below trench grade. Soil unsuitable for a proper foundation encountered at or below trench grade, such as muck or other deleterious material, shall be removed for the full width of the trench and to the depth required to reach suitable foundation material, unless special design considerations received prior approval from the city. Backfilling below trench grade shall be in compliance with the applicable provisions of division (K) below.
(D) Extra utility-bedding material. When rock or other non-cushioning material is encountered at trench grade, excavation shall be extended to six inches below the outside of the bottom of the utility, and a cushion of sand or suitable crushed rock shall be provided.
(E) Sheeting and bracing. In order to prevent damage to property, injury to persons, erosion, cave-ins, or excessive trench widths, adequate sheeting and bracing shall be provided in accordance with standard practice.
(F) Excavated material. Excavated material to be used for backfill shall be neatly deposited at the sides of the trenches where space is available. Where stockpilings of excavated material is required, the contractor shall be responsible for obtaining the sites to be used.
(G) Material disposal. Excess, unsuitable, and cleared or grubbed material resulting from the utility installation, shall be removed from the work site and disposed of at locations secured by the contractor. Excess excavated material shall be spread on the disposal site and graded in a manner to drain properly and not disturb existing drainage conditions.
(H) Borrow. Should there be insufficient satisfactory material from the excavations to meet the requirements for fill material, borrow shall be obtained from pits secured by the contractor.
(I) Dewatering. Utilities shall be laid "in the dry" unless otherwise approved. Dewatering system shall be utilized in accordance with good standard practice and must be efficient enough to lower the water level in advance of the excavation and maintain it continuously to keep the trench bottom and sides firm and dry.
(J) Obstructions. It shall be the contractor's responsibility to acquaint himself with all existing conditions and to locate all structures and utilities along the proposed utility alignment in order to avoid conflicts. Where actual conflicts are unavoidable, work shall be coordinated with the facility owner and performed so as to cause as little interference as possible with the service rendered by the facility disturbed.
(K) Backfill.
(1) Backfill material shall be clean earth fill composed of sand, clay and sand, sand and rock, crushed rock, or an approved combination thereof.
(2) When trenches are cut in pavements or areas to be paved, compaction as determined by AASHO Specification T-180, shall be equal to 98% of maximum density, with compaction in other areas not less than 95% of maximum density.
(3) If, in the opinion of the city, densities are questionable, density tests for determination of the above specified compaction shall be made by testing laboratory approved by the city at the expense of the contractor. Test locations will be determined by the city.
(4) If any test results are unsatisfactory, the contractor shall re-excavate and re-compact the backfill at his expense until the desired compaction is obtained.
(5) Protective concrete slabs shall be installed over the top of trenches, where required, to protect the installed pipe against excessive loads.
(6) Existing sidewalks and driveways removed, disturbed, or destroyed by construction, shall be replaced or repaired.
(L) Roadway and pavement restoration.
(1) Pavement or roadway surfaces cut or damaged shall be replaced by the contractor in equal or better condition than the original, including stabilization, base course, surface course, curb and gutter, or other appurtenances. The contractor shall obtain the necessary permits and all applicable authorizations from the proper agencies prior to any roadway work. Additionally, the contractor shall provide advance notice to the appropriate authority, as required, prior to construction operations.
(2) Restoration shall be in accordance with requirements set forth by the city. The materials of construction and method of installation, along with the proposed restoration design for items not referred to or specified herein, shall receive prior approval from the department.
(3) Where existing pavement is removed, the surfacing shall be mechanically saw cut prior to trench excavation, leaving a uniform and straight edge, with minimum disturbance to the remaining adjacent surfacing. The width of cut of this phase of existing pavement removal shall be minimal.
(4) Immediately following the specified backfilling and compaction, a temporary sand seal coat surface shall be applied to the cut areas. This temporary surfacing shall provide a smooth traffic surface with the existing roadway and shall be maintained until final restoration.
(M) Protection and restoration of property. During the course of construction, the contractor shall take special care and provide adequate protection in order to minimize damage to vegetation, surface areas, and structures within the construction of right-of-way, easement or site, and take full responsibility for the replacement or repair thereof.
(N) Clean-up. Work site clean-up and property restoration shall follow behind construction operations without delay.
(Ord. 348, passed 12-3-87) Penalty, see § 77