SECTION: 33 30 00 SANITARY SEWERAGE
Note: Sanitary systems owned and operated by American Water are constructed/maintained by American Water. The following is for JBLM owned sanitary systems.
Changes or Criteria Notes to Unified Facilities Guide Specifications (UFGS)
Paragraph # and Title (if any)
Note to Designer
2.2.17 Manhole Steps
Add the following:
Manhole steps shall be constructed to meet all requirements of ASTM C-478, be rated for a minimum 300-foot-pound concentrated load, and meet the latest OSHA requirements. Co-polymer polypropylene steel-reinforced steps are recommended, with the steel core specified as a minimum half-inch-steel bar fully enclosed in the co-polymer polypropylene.
22.214.171.124 Hydrostatic Sewer Test
If used, the required minimum test pressure:
150-psi in excess of that under which they will operate.
- Construction of new sewer systems or extensions of existing systems will be allowed only if the existing receiving system is capable of supporting the added hydraulic load.
- Collection and interceptor sewers shall be designed for the ultimate development of the tributary areas.
- Sewer systems shall be designed and constructed to achieve total containment of sanitary wastes and maximum exclusion of infiltration and inflow.
- Construction of new sewer service connections, including extensions of existing systems will be allowed only after the discharge has received a discharge characterization and approval from the Public Works Environmental Division Pretreatment program manager.
- Whenever possible, the sewer main shall run parallel to and 5 feet southerly or westerly of street centerline. The sewer main shall maintain a minimum 10 foot horizontal separation from proposed or existing water mains.
- All sewers shall be designed to prevent damage from superimposed loads. Proper allowance for loads on the sewer because of the width and depth of trench should be made. When standard-strength sewer pipe is not sufficient, extra-strength pipe, or sleeves, shall be used.
- For sanitary sewers constructed of flexible pipe, engineers should test for deflection not less than 30 days after the trench backfill and compaction has been completed. The engineer must conduct the test by pulling a properly sized “go/no-go” mandrel through the completed pipeline. On a manhole-to-manhole basis, the engineer will conduct the testing after the line has been completely flushed out with water.
- Designer shall determine depth of pipe based on project requirements, and determine loading anticipated on pipe and select appropriate pipe. The allowable cover (finished grade) for the various types of pipe shall be as recommended by the manufacturer.
- Minimum cover over sewer pipes must be 2 feet; or sufficient to support imposed dead and live loads for the pipe materials used; whichever is more stringent. Under roadway, cover shall not be less than 3 feet deep.
- All sewers shall be designed and constructed to give mean velocity, when flowing full, of not less than 2.0 fps. Self-cleaning velocity shall be provided and demonstrated by the engineer. See WA DoE Orange Book (2008) Table C1-1 Minimum slope of sewers for minimum allowable slopes; however slopes greater than those listed are desirable.
- Bedding material shall be as specified in WSDoT Standard Plans B-55.20-02 Pipe Zone Bedding and Backfill including linked requirements to WSDoT Standard Specifications.
- Manholes shall be installed at all intersections and at distances not greater than 400 feet for sewers less than 18 inches in diameter, and 500 feet for sewers with diameters of 18 inches to 30 inches provided the velocity is sufficient to prevent sedimentation of solids.
- All manholes shall be accessible to maintenance vehicles. Manholes located out of roadways shall be provided with a manhole locator marker post.
- Terminating manholes, where sewer extension may occur, shall be provided with knock-outs and channeled accordingly.
- Invert elevations at beginnning and end of pipelines and at manholes or similar structures are required.
- Stamp or cast the words "Sanitary Sewer" into covers so that it is plainly visible.
- The ends of all pipes shall be trimmed flush with the inside walls of the manhole.Flexible pipes connecting to sanitary sewer manholes shall be provided with an entry coupling or gasket. No pipe joint in flexible pipe shall be placed within 10 feet of the manhole.
- Rigid pipes connected to the sanitary sewer manhole shall be provided with a flexible joint at a distance from the face of the manhole of not more than 1.5 times the nominal pipe diameter or 18 inches, whichever is greater.
Restoration: Road restoration shall be per JBLM Design Standards.Lift Stations: Lift stations shall be built according to UFGS 33 32 16 Packaged Utility Wastewater Pumping Stations Demolition/abandon: Pipes within 5 feet of surface should be removed. All abandoned pipes should be removed if feasible. Backfill (pressure grout) is required for pipes 12 inches in diameter or greater.
- All side sewers constructed in conjunction with the main sewer shall, for purposes of testing, have a 6-inch tee fitting pipe placed at the point where the side sewer crosses the street or specified location outside paved area. The tee opening shall be positioned perpendicular to the side sewer slope, unless otherwise directed by the Engineer..
- For side sewers that are not connected during construction, The location of side sewers at the property line shall be marked by the Contractor with a 2 by 4-inch wooden stake 4 feet long buried in the ground a depth of 3 feet. The low end shall have a 2 by 4-inch cleat nailed to it to prevent withdrawal of the stake. The exposed end shall be painted traffic white and the depth to the side sewer or tee shall be indicated in black paint on the 2 by 4. In addition, a length of 12-gage galvanized wire shall be provided to extend from the plugged end of the side sewer or tee. The upper end shall emerge at the 4-foot stake, but shall not be fastened to it.
- Connect pipe to existing manholes such that finish work will conform as nearly as practicable to the applicable requirements specified for new manholes, including all necessary concrete work, cutting, and shaping.
Notes to Designers on Drawing Content
- Detailed plans shall be submitted for review which provide the location, size, type and direction of flow of the proposed sewers and the connection with existing sewers. These plans shall be separate from water plans unless otherwise directed by Public Works.
- All survey control shall be based on the nearest Corps of Engineer’s benchmarks. Project plans shall have a horizontal scale of not more than 50 feet to the inch and a vertical scale of not more than 5 feet to the inch. Plans and profiles shall show:
- Locations of streets, existing utilities, and sewers, ground surface, pipe type, class and size, manhole stationing, invert and rim elevation at each manhole, and grade of sewer between adjacent manholes. All manholes shall be numbered on the plans and correspondingly numbered on the profile. Where there is any question of the sewer being sufficiently deep to serve any structure, the elevation and location of the basement floor, if basements are served, shall be plotted on the profile of the sewer which is to serve the structure in question. All sewers shall be sufficiently deep to serve adjacent basements, except where otherwise noted on the plans.
- All known existing structures, both above and below ground, which might interfere with the proposed construction, particularly water mains, gas mains, storm drains, overhead and underground power lines, telephone lines, and television cables shall be indicated including all utility easements.
- Details included in the plan set shall clearly show special sewer joints and cross-sections, and sewer appurtenances such as manholes and related items.
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