(a) An owner must include manholes in a collection system at:      
        (1) all points of change in alignment, grade, or nominal diameter;       
        (2) at all intersections of collection system pipes; and       
        (3) at the end of all pipes that may be extended at a future date.       
      (b) Manholes placed at the end of a collection system pipe that may be extended in the future must include pipe stub outs with plugs.     
      (c) A cleanout with watertight plugs may be installed in lieu of a manhole at the end of a collection system pipe if no extensions are anticipated.     
      (d) Cleanout installations must pass all applicable testing requirements outlined for gravity collection pipes in §217.57 of this title (relating to Testing Requirements for Installation of Gravity Collection System Pipes).     
      (e) A manhole must be made of monolithic, cast-in-place concrete, fiberglass, pre-cast concrete, high-density polyethylene, polymer concrete, or other material designed to withstand the anticipated live and static loads.     
      (f) The use of bricks to adjust a manhole cover to grade or construct a manhole is prohibited. Adjustment rings used to adjust a manhole cover to grade must be constructed of concrete, high density polyethylene, or other material that is designed to withstand the anticipated live and static loads.     
      (g) Manholes may not be spaced farther apart than the distances specified in the following table for a wastewater collection system with straight alignment and uniform grades. The executive director may approve different distances, in writing, if the owner has equipment that can clean longer distances.      
        Attached Graphic       
      (h) Tunnels are exempt from manhole spacing requirements.     
      (i) A manhole must not be located in a stream bed or other area that prevents access to the manhole.     
      (j) The inside diameter of a manhole must be no less than 48 inches. A manhole diameter must be sufficient to allow personnel and equipment to enter, exit, and work in the manhole, and to allow proper joining of the collection system pipes in the manhole wall.     
      (k) Manholes must meet the following requirements for covers, inlets, and bases.      
        (1) Manhole Covers.                  (A) A manhole where personnel entry is anticipated requires a clear opening with at least a 30 inch diameter.                   (B) A manhole located within a 100-year flood plain must be gasketed and bolted down to prevent inflow.                   (C) A manhole cover must be constructed of impervious material with no holes that could allow inflow.                   (D) A manhole cover that is located in a roadway must meet or exceed the American Association of State Highways and Transportation Officials standard M-306 for load bearing.                   (E) The engineering report must specify and the owner must follow an appropriate national reference standard for manhole gaskets.                   (F) Manhole covers must be constructed of cast iron, steel, non-metallic composite material, fiberglass, or other material approved in writing by the executive director.         
        (2) Manhole Inverts.                  (A) The bottom of a manhole must contain a U-shaped channel that is a smooth continuation of the inlet and outlet pipes.                   (B) A manhole connected to pipes less than 15 inches in diameter must have a channel depth equal to at least half the largest pipe's diameter.                   (C) A manhole connected to a pipe that is at least 15 inches in diameter but not more than 24 inches in diameter must have a channel depth equal to at least three-fourths of the largest pipe's diameter.                   (D) A manhole connected to a pipe that is greater than 24 inches in diameter must have a channel depth equal to at least the largest pipe's diameter.                   (E) In a manhole with pipes of different sizes, the tops of all the pipes must be at the same elevation and flow channels in the invert must be sloped evenly from pipe to pipe to prevent backpressure.                   (F) A bench provided above a channel must slope at a minimum of 0.5 inch per foot.                   (G) A manhole invert must be filleted to prevent solids from being deposited if a collection system pipe enters a manhole higher than 24 inches above a manhole invert.                   (H) A collection system pipe entering a manhole more than 24 inches above an invert must have a drop pipe.         
      (l) Steps are prohibited in a manhole.     
      (m) Connections. A manhole-pipe connection must use watertight, size-on-size resilient connectors that allow for differential settlement and must conform to American Society for Testing and Materials C 923.     
      (n) Venting.      
        (1) An owner must ensure that the collection system is vented at least every 1,500 feet.       
        (2) Vents must be designed to minimize inflow and must be located above a 100-year flood event elevation.       
        (3) Tunnels must be vented in compliance with this subsection.       
      (o) Cleanouts. A cleanout diameter must be at least equal to the diameter of the pipe to which it is attached.     
     Source Note:        The provisions of this §217.55 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254