(a) Improvements, enlargements and extensions to the sewage works system shall be subject to the approval of Council with regard to design, construction, operation and financing. Where construction and financing are to be by private organizations, the organizations shall furnish a maintenance and guarantee bond in the amount of 10% of the estimated cost of construction and running for a period of one year after completion of construction and acceptance by the city. Prior to the approval of the plans for improvements, enlargements and extensions, the private organizations shall deposit with the city a sum equal to 2.25% of the estimated cost of construction to cover inspection costs. Any unused balances of the deposits remaining after completion and acceptance of the construction shall be refunded.
(b) All sewage works system improvements, enlargements and extension whether installed by a public agency or a private organization shall conform to the standards as set forth herein.
(1) Sanitary sewers.
A. Sanitary sewers shall not be less than eight inches in diameter and/or of adequate size and capacity to serve their tributary area on the design basis of 100 gallons of daily sewage flow per capita per day. Design not to exceed pipe one-half full or as determined by the Public Utilities Director. Slope of the sanitary sewers shall be so as to provide a minimum velocity of two feet per second or a maximum velocity of 15 feet per second when the sewer is flowing full and the appropriate pipe roughness coefficient, using a coefficient factor (roughness) N = 0.013, as approved by the Public Utilities Director is utilized. Sanitary sewers must be of a type pipe approved by the Director, in accordance with the standard of extra strength specifications of the American Society for Testing and Materials as amended to the date of installation. Where the depth of the trench from finished grade to the top of the sewer pipe exceeds ten feet, the extra strength pipe shall be used. The city reserves the right to specify and require the encasement of any sewer pipe with concrete or the installation of the sewer pipe in concrete cradles if foundation and construction conditions are such as to warrant the protection in the opinion of the Director.
B. Concrete, steel or PVC pipe of suitable diameters and thickness or tunnel liners of adequate internal diameter shall be installed for encasement or enclosures of sanitary sewers to be constructed under all railroads and where directed by the Public Utilities Director for the crossing of the main highways. Joints for sanitary sewers shall be in accordance with ASTM specifications, as amended to the date of installation and all subject to the approval of the Director. The pipe shall be installed according to the manufacturer’s directions and as approved by the Director. Sanitary sewers shall be of the design and construction that infiltration or exfiltration shall conform to city specifications. Leakage tests shall be conducted by the contractor, at his or her expense, in the presence of the Public Utilities Director or an authorized Inspector. The leakage tests shall be performed between manholes and then measuring the rate of details of the method shall be subject to the approval of the Director. The rate of leakage so determined shall be understood to be the equivalent of the infiltration specified above. Sanitary sewers shall be constructed in strict accordance with the standard specifications of the American Society for Testing and Materials, designation C12-58T, and as amended at date of installation except as modified herein.
(Ord. 90-61, passed 5-14-1990)
(2) Manholes. Manholes shall be constructed of precast concrete, complete with cast iron frame cover and steps in accordance with the standard detail drawings on file in the office of the City Manager, unless otherwise approved by the Public Utilities Director. Distance between manholes shall not exceed 400 feet, unless otherwise approved by the Public Utilities Director.
(Ord. 91-90, passed 9-23-1991)