(a) A sanitary sewage disposal system serving all lots in any subdivision shall be required.
(b) Where a public sanitary sewer system is available as determined by the City, every lot within the subdivision shall be provided with a connection thereto.
(c) Where a public sanitary sewer is not accessible as determined by the City, the subdivider shall be required to provide an acceptable disposal system subject to the approval of the City or County agency having jurisdiction.
(d) Materials and specifications for the design and construction of sanitary sewage disposal facilities as required by this section shall be in conformity with current specifications on file in the office of the City Service Director and Water Operator in charge.
(e) Design Standards for Sanitary Sewers.
(1) Design capacity:
Average flow | 400 gallons per day - single-family dwelling |
Peak flow factor | Trunk sewer - 2.7 Local sewer - 4.0 |
Pipe coefficient of friction | N = .013 |
(2) Minimum design velocity: 2 fps when sewer is flowing at average daily flow rate or 1/4 full.
(3) Maximum infiltration allowance: 50 gallons/inch/mile/day.
(4) Acceptable pipe materials:
Composite ABS or PVC | ASTM D-2680, joints D-2235 PVC (depth limit 25 feet) |
PVC plastic sewer pipe | ASTM D-3034, joints D-3212 |
Depth limitations for PVC | 1 to 16 feet deep - SDR 35 16 to 25 feet deep - SDR 26 |
(5) Minimum sewer size: No sewer shall be less than 8 inches in diameter. Trunk sewers shall be sized in accordance with master plans in the Office of the Service Director and Water Operator in charge.
(6) Minimum grade: All sewers shall have a minimum grade of 0.5% unless it can be shown by the above design criteria that the sewers shall have sufficient cleaning velocity (2 feet per second) at lesser grades. Sections of sewer that shall have the equivalent of 10 or less single-family dwellings connected upstream from it shall have a minimum grade of 0.8%. If cleaning velocities (2 feet per second) can be documented, the minimum grades for sewers 8 inches to 15 inches are as follows:
8 inches | 0.40% |
10 inches | 0.28% |
12 inches | 0.22% |
15 inches | 0.15% |
Sewers larger than 15 inches shall be reviewed on an individual basis | |
(7) Manholes:
A. Sections: Precast reinforced concrete ASTM C-478; C76 wall B with ASTM C-443 joints.
B. Connections:
Rubber sleeve w/stainless steel banding | "Kor-n-seal" by National Pollution Control Systems, Inc., or "Lock Joint" by Interpaca Corporation or equivalent |
Rubber gasket compression | Press Wedge II by Press-Seal Gasket Corporation or Dura-Seal by DuraTech Incorporated or equivalent |
C. Connections to existing manholes: Must be core drilled and rubber gasket installed. No "hammer taps" will be permitted.
D. Frames and covers: Iron castings of the heavy-duty pattern (with the word "sewer" cast in).
Vented and solid covers | Neenah R-1767 or equal, where flush with finished grade |
Locking covers | Neenah R-1926-B, or equal bolted down to the cone section with four 7/8-inch x 9-inch anchor bolts, where frames are above the finished grade, off highway |
Watertight | Neenah R-1916-F or equal, where required by the engineer |
E. Steps: Extruded aluminum conforming to ASTM B221, 6061.
(8) Bedding material: Clean granular material - Aggregates not to be larger than 3/4-inch and not smaller than Number 8 sieve, free of silt and fines, ASTM D-2321 Class 1B for pipe sizes 8 inches to 15 inches. Bedding to be a minimum of 6 inches below and 12 inches above the pipe.
(9) Manhole spacing: Manholes shall be located at all changes in sewer size, material, grade and alignment. Manholes shall also be located at all junctions of public sewer. Maximum spacing for all pipe sizes is 400 feet.
(10) Inspection:
A. Requirements: An authorized agent of the City must inspect all work and materials. Contractors must notify the Service Director at least 24 hours in advance of initiating construction or amending a construction schedule.
B. Fees: Fees are to be paid and set according to a schedule kept by the Service Director and Water Operator in charge that have been adopted by City Council.
C. Tests: Air test per City standards for low pressure air testing. Specifications can be found in the office of the Service Director. Vacuum test at least 25% of the manholes to be selected by the Service Director in accordance with ASTM C-1244. If more than 5% of the manholes tested fail the initial test, an additional 25% of the manholes shall be tested.
D. Acceptance: Initial acceptance will be made when the sewer mains and all appurtenances have been installed, tested and approved and a 1-year 10% maintenance bond is submitted. Final acceptance will be made and the maintenance bond released when final grade is established, appurtenances are adjusted to final grade, and at least one full year of satisfactory operation is achieved.
(11) Private sewer laterals: A private sewer lateral shall be installed for each lot or building site during the construction of local sewers. Said private sewer laterals shall terminate at a point 12 feet inside of the property line or right-of-way line. Said laterals shall be 6 inches in diameter.
(12) Sewer easements: Sewers installed outside the public right-of-way shall reside in an easement having a minimum width of 20 feet (10 feet each side of the sewer). Private sewer laterals installed within said easement shall extend to the edge of the easement.
(13) Extension to development boundaries: All sewers shall be extended to the upstream boundary of the property or development being served except for those areas where the natural or planned topography makes it unreasonable to plan for later extensions of the sewer.
(Ord. 12-2002. Passed 7-2-02.)