Unit III - Sanitary Sewer Design Standards - City of Fort Wayne

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Water Resources Development Criteria/Standards Manual Chapter 3UNIT III – Sanitary Sewer Design StandardsPublic Sewers3.3.3 StationingAll sewer stations shall increase upstream. Stationing on manhole structures shall be atthe structure centerline. Every effort shall be made to begin the stationing of a sewerwith Station 0+00.00 at the downstream end. For sewers not requiring curved sections,the PI stations and deflection angles or interior angles shall be shown on the plans at allchanges in alignment.3.3.4 Minimum Horizontal Separation from Water LinesSanitary sewer shall be laid at least ten feet (10’) horizontally from any existing orproposed water main. The distance shall be measured edge to edge. In instances where itis not possible to maintain a ten foot (10’) separation, the authorized agency may allowdeviation on a case-by-case basis. This deviation may allow installation of the sanitarysewer closer to the water main, provided that the water main is in a separate trench or onan undisturbed earth shelf located on one side of the sewer and at an elevation so thebottom of the water main is at least 18 inches (18”) above the top of the sanitary sewer.If it is impossible to maintain proper separation as described above, both the water mainand sanitary sewer must be constructed of slip-on mechanical joint pipe complying withthe water supply standards outlined in Unit IV of this Manual and be pressure tested to150 psi to assure watertightness before backfilling. In all instances when separationcannot be maintained, Water Resources shall be consulted for guidance and approval.All sewers shall be constructed with a straight alignment between manholes. Wheresewer depth is ten feet (10') or less, sewer lines and manholes shall be located a minimumof ten feet (10') horizontally from any part of a building structure or its foundation. Forsewer depths greater than ten feet (10'), this minimum distance shall be 15 feet (15').3.3.5 Rear Lot AlignmentIn certain limited situations, rear lot sewer alignment shall be considered. Writtenapproval from Water Resources for such an alignment will be required. When rear lotalignment is utilized, an exclusive sewer easement shall be required and the sewer shallnot be located within drainage swales.3.3.6 Minimum Distance from Additional UtilitiesAll plans shall show the location of both underground and overhead utilities. Thelocation of the utilities shall be derived from the best information available. Each of theutilities shall receive a set of plans prior to final submittal on which they may notechanges or additions to utility information. The adequacy of the separation of thesanitary sewer line and other utility shall be determined by both the appropriate utilitycompany and the design engineer. Any necessary relocations shall be closelycoordinated with the respective utility company.Created: January 1, 2002 III - 3 - 4 City of Fort WayneRevised:
Water Resources Development Criteria/Standards Manual Chapter 3UNIT III – Sanitary Sewer Design StandardsPublic Sewers3.3.7 Location in Relation to Streams and WaterwaysSewers located along streams and waterways shall be located outside of stream beds andsufficiently removed therefrom to allow for future possible stream widening and toprevent pollution by siltation during construction.3.4 Vertical Alignment Criteria3.4.1 Sewer DepthsSanitary sewers shall have a minimum cover of four feet (4’) as measured from the top ofpipe. Exceptions to this requirement will be addressed by Water Resources on a case-bycasebasis.Basement elevations shall also be taken into account. In instances where only a limitednumber of houses on the sanitary sewer have existing basement facilities, the overallimpact on the entire system shall be considered prior to providing gravity basementservice. In areas where the lowest building level to be served by gravity sanitary sewerservice is less than one foot (1’) above the top of the manhole casting elevation of thefirst upstream manhole on the public sewer to which the connection is made, the DesignEngineer shall design for backflow prevention devices to prevent sanitary sewer backups.The sanitary sewer elevation necessary to serve the entire tributary area shall beconsidered when designing a sanitary sewer line. This design shall include areas beyondthe boundary of a design section.In areas where excessive depths are encountered in the sanitary interceptor sewer, aseparate parallel sanitary sewer collector line constructed at a higher elevation shall beconsidered. The parallel line would end in a drop manhole structure as opposed toindividual property service connections to the interceptor line. Approval of a parallelinterceptor line must be granted by Water Resources.3.4.2 Minimum Vertical Separation from Water LinesA minimum vertical separation of 18 inches (18”) between the outside of water main andthe outside of the sanitary sewer shall be maintained. The distance shall be measurededge to edge. The crossing shall be arranged such that sewer joints shall be as far aspossible from water main joints. Every effort shall be made to construct the sewer belowthe water main. Where a water main crosses beneath a sewer, structural support andexfiltration testing shall be provided to ensure the integrity of the water main. Ininstances where it is not possible to maintain an 18-inch (18”) vertical separation, theauthorized agency may allow deviation on a case-by-case basis. This deviation mayallow installation of the sewer closer to the water main, provided that the water main is ina separate trench or on an undisturbed earth shelf located on one side of the sewer and ata horizontal separation of at least ten feet (10’) as measured edge to edge.Created: January 1, 2002 III - 3 - 5 City of Fort WayneRevised:
Page 1 and 2: Water Resources Development Criteri
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Page 67 and 68: Exhibit III-2-5City Utilities Sanit
Page 69 and 70: Exhibit III-2-7City Utilities IDEM
Page 71 and 72: Exhibit III-3-1City Utilities Waste
Page 73: Exhibit III-3-3City Utilities Minim

Unit III - Sanitary Sewer Design Standards - City of Fort Wayne

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