Wastewater Service Design Criteria

Design Criteria

The requirements below are critical items required by Tennessee Department of Environment and Conservation (TDEC) and the Rules, Regulations, Rates, and Policies of LCUB's Water Department. The engineer must ensure all requirements are met. LCUB strongly recommends a pre-design conference to review the development layout, including topography and sewer features, to ensure a successful project.

TDEC Requirements

The following items are required by TDEC's General and Detailed Plans of Water Distribution Systems:

TDEC Requirements: General Plan of Sewer

  1. All plans must be approximately 24" x 36"
  2. Plans must include a location map.
  3. The plans shall show the location, size, and direction of flow of all proposed and existing sewers draining to the concerned treatment facility.
  4. Plans must be stamped and signed by a licensed engineer.
  5. Hydraulic calculations are required for all lines in the project. All receiving lines must be shown to be adequate for the proposed project and must appear either on the plans or in the supplementary report using the TDEC format (TDEC Design Criteria for Sewage Works Item 2.1.5 / Appendix 2-B).
  6. Topography and elevations, both existing and any changes proposed, and all bodies of water (including the direction of flow and high water elevations) should be clearly shown.

TDEC Requirements: Plan and Profiles of Sewers

  • Profiles for sewer detail should have a horizontal scale of not more than 50 feet to 1 inch (LCUB's requirement is more restrictive than TDEC) and a vertical scale of not more than 10 feet to 1 inch. Plan views should be drawn to a corresponding horizontal scale.
  • Plans and profiles should show:
    • Locations of streets and sewers.
    • Sewer Details - Lines of ground surface, pipe type and size, manhole stationing, invert and surface elevation at each manhole, and grade of sewer between adjacent manholes. Manholes should be labeled on the plan and also on the profile correspondingly. MH of distance should be less than 350 feet.
    • When there is any question of the sewer being sufficiently deep to serve any residence or other source, the elevation and location of the basement floor or other low point source shall be plotted on the profile of the server which is to serve the house or source in question.
    • Locations of all special features, such as inverted siphons, concrete encasements, elevated sewers, and flow monitoring key manholes.
    • Location of all existing structures below and above ground which might interfere with the proposed construction; particularly water mains, gas mains, storm drains, etc.
    • Detailed drawings of all stream crossings with elevations of the stream bed and or normal and extreme high and low water levels to include 25- and 100-year flood plain (see TDEC 2.4.3 Sewers in Relations to Streams).
      o Detailed drawings of special sewer joints, cross sections, and appurtenances such as manholes, flush valves, inspection chambers, etc.
    • Location of adjacent streams and the extent of streamside vegetation.
    • General topography, including trees within 25 feet of center lines, of the proposed sewer main.

LCUB Requirements

LCUB requires the following items, in addition to the list above:

  • The first page of the plans must include the following:
    • The developer's name, address, and phone number.
    • The property owner's name, address, and phone number.
    • The engineer's name, address, and phone number.
    • Servicing utility's name, address, and phone number (LCUB, 200 Depot Street, Lenoir City, TN 37771, (865) 986-6591).
  • The items below must be included in the plans:
    • Profiles must be on the same sheet as the plan and oriented in the same direction.
    • Overall project and project layout map with project name and design date.
    • Rights of way and easements needed for the water that falls inside / outside of the property.
    • Lot lines and locations shown on all plan views, including lot numbers.
    • Street names, edge of pavement locations, and the appropriate rights of way.
    • Location and size of services including the distance upstream from downstream manhole and length of 6 inch lateral and depth of the lateral needed at the end of the lateral to serve the lot.
    • Inverts for the manholes including inlet inverts and outlet inverts, rather than a single manhole, and the centerline invert. The outlet invert should be a minimum of 0.1 feet lower than the invert.
    • Manhole deflection angles.
    • A 100 foot stationing of sewer lines and stationing of all appurtenances on plan and included profile views.
    • Project name, date, scale, north arrow, and sheets numbers on all pages.
    • Inclusion of all LCUB detail sheets.
    • Revisions tabulated on resubmissions.
    • Inclusion of all benchmarks. All plans must include the establishment of a minimum of one benchmark for each project. Benchmark and its elevation are to be shown on the plan set. Benchmark must be maintained through the completion of the project.
  • The developer (owner) and / or contractor must adhere to LCUB Standard Specifications and Details,
  • The engineer shall provide documentation of the existing and new sewer collections system's Hydraulic Analysis.
  • The Sewer Collection System must be a minimum of 8 inch diameter. Gravity sewers 12 inches or less in diameter shall be either ductile iron pipe or PVC (SDR 35). Ductile iron pipe shall be used for trench depths of 12 feet or greater and roadways (No Exceptions). Gravity sewers greater than 12 inches in diameter shall be Class 150 ductile iron pipe.
  • Upon review of the plans, LCUB has the right to require the Sewer Collection System to be a larger diameter pipe size or ductile iron pipe in lieu of 8 inch based on the hydraulic analysis, depth, soil, and future conditions.
  • The developer (owner) and / or contractor is responsible for any existing sewer collection system improvements required to provide hydraulic sewer capacity to the new development and maintain the existing / future hydraulic sewer capacity.
  • The developer (owner) and / or contractor is responsible for installing all 6 inch sewer taps, 6 inch sewer lines, and 6 inch 2-way cleanout (Plastic Trends G1006) per LCUB Standards and Specifications for the new development.
  • The Sewer Lateral Discharge (Main Floor Elevation) must be a minimum of 6 inches above the top of the lowest of the two adjacent manholes.
  • The developer (owner) and / or contractor is responsible for installing a minimum of SDR 35 pipe for sanitary sewer services to a depth of 12 feet. Any sanitary sewer services that are over 12 feet deep shall require water line and / or mechanical joint quality pipe.
  • A Low Pressure Sewer System will not be approved for acceptable sewer service.

Design Notes

The following notes must appear on all plans:

  1. All work to be performed will be in accordance with lenoir city utilities board's water and wastewater department (current edition) specification and details.
  2. Pre-construction conference shall be conducted with lenoir city utilities board's representatives, design engineer, and utility contractor prior to any utilities construction activities beginning.
  3. Sewer line materials, installation and testing per lenoir city utilities board water and wastewater department standards (current edition).
  4. All service laterals shall be 6" to property line and installed at a minimum 1% slope unless field verified by the engineer. . A 6" x 4" increaser bushing - eccentric (part number 32642) shall be used for single family residential connection.
  5. Service laterals cleanout shall be a 2-way cleanout as manufactured by plastic trends (g1006) and extend 3" above finished grade to mark sewer service connections until building connection is made..
  6. Sewer lateral discharge (main floor elevation shall be a minimum of 6" above the top of the lowest of the two adjacent manholes.
  7. No individual e-one grinder pump systems shall be used on this project. Individual basement pumps may be used and maintained by the property owner in order to pump basements to the main level (where necessary).
  8. If pump stations are required for a project, they must be approved by lcub and must be submersible flyght pump stations.
  9. Construction and inspection must be supervised by lcub and / or a representative of the design engineering firm so that the required professional engineer certification can be made to lcub. Lcub will not accept utilities that have not been certified in writing. All associated costs will be reimbursed by the developer.