(a) Plans. Any person intending to install trunk line and interceptor sewers, which are to be a part of or connected with the City sewer system, shall submit to the Service Director, for his approval, plans governing the proposed design. Such plans shall indicate for the purpose of analysis the following:
(1) Area of lands to be served, in acres.
(2) Estimated number of persons per acre.
(3) Area of land which possibly may be connected to the proposed system in the future, in acres.
(4) Gallons per day average flow, based on one hundred gallons per day per person.
(5) Gallons per day of permitted industrial flow, if any.
(6) Infiltration allowance.
(7) Total flow.
(8) Future increase estimated.
(9) Total future average daily flow.
(10) Maximum daily future flow.
(11) Slope of sewer.
(12) Pipe sizes.
(13) Percentage depth of flow.
(14) The velocity of such sewers flowing one-half full shall not be less than two feet per second to prevent settling out of solids, nor more than eight feet per second, unless special conditions warrant.
(15) The trench loading on the sewer and the strength of pipe and type of installation to be followed to adequately support the calculated trench load.
(b) Structural Requirements. Any person installing trunk lines or interceptor sewers, which are to be a part of or connected with the City sewer system, shall install such sewers according to specifications set forth in this section, and in accordance with the following rules and regulations:
(1) Lines and grades.
A. Grade stakes shall be set not more than fifty feet apart and shall establish both lines and grade.
B. Batter boards shall be used to carry a grade string.
C. A grade rod shall be used to establish the grade of the trench and to set each pipe.
(2) Supplementary foundations.
A. If the bottom of the trench is not sufficiently stable or firm to prevent vertical or lateral displacement of the pipe after installation, supplementary foundation shall be used irrespective of loading requirements.
B. The type of supplementary foundation to be used shall be sand and gravel to stabilize the trench bottom or concrete, cradle, timber or masonry bridging supported upon a pile foundation, as determined by the Municipal engineering representative.
C. Pipe laid in rock trenches shall be supported on a supplementary foundation of at least four inches of clay cushion or sand and gravel cushion to support the bottom quadrant.
(3) Tamping.
A. Tamping to prevent lateral displacement of the pipe shall be accomplished by tamping coarse graded backfill in successive layers of not more than six inches each, to a depth of at least eighteen inches above the pipe. The remainder of the backfill shall be reasonably uniform, free from large stones and chunks of frozen material.
B. Where pavement is to be placed or replaced over the trench, the compaction of the backfill shall be in accordance with State highway specifications for soil compaction requirements.
(4) Manholes.
A. The manholes shall have a minimum bottom diameter of four feet inside and provide for a two-foot clear opening through a cast iron frame and cover at the top. The top elevation shall be that of the existing or proposed finished street grade.
B. Materials of construction shall be eight-inch concrete base at least six inches larger than the outside diameter of the manhole as measured at the flow line.
C. The walls shall be either brick or precast concrete.
D. Brick walls shall not be less than eight inches thick, and thicker walls shall be required where, in the opinion of the City, heavier wall construction is necessary.
E. Precast concrete manholes shall be Salem City Standard or equal, subject to approval of the City before installation.
F. A minimum of three-eighths inch plaster coat shall be placed inside and outside the brick masonry walls.
(5) Storm water.
A. Storm water runoff shall not be permitted in sanitary sewers either during or after construction.
B. During construction the contractor or others shall use every precaution in blocking the entrance of storm water into sanitary sewers at all times with suitable expansion plugs or heavy sand bags.
(c) Inspections. Any person constructing a sewer which is to be connected to the sewer system of the City shall have an inspector at the site of the work during the entire construction period. Such inspector shall be furnished by the City and shall be available as nearly as possible during the entire working period. The cost of such inspector furnished shall be paid by the person installing the sewer system at the prevailing rate of pay received by the inspector.
(d) Retainer Fee. The person shall deposit with the City a retainer fee prior to the start of the work of sixteen cents (16¢) per foot of pipe as indicated on the plans. Such retainer fee shall be used to defray the cost of the inspector but shall not relieve the above persons from paying the entire inspection cost should it exceed the retainer fee.
(e) Liability of Installers. The person installing such sewer system shall save harmless the City and its authorized agents or representatives for all damages to persons or property, public or private, and shall be liable for all maintenance of sewers, due to faulty construction or materials, for a period of twelve months after formal acceptance of the sewer by the City authority.
(Ord. 880216-14. Passed 3-15-88.)