1. (a) An owner must include manholes in a wastewater collection system at:

   1. (1) all points of change in alignment, grade, or size;
   2. (2) at the intersection of all pipes; and
   3. (3) at the end of all pipes that may be extended at a future date.
2. (b) Manholes placed at the end of a wastewater collection system pipe that may be extended in the future must include pipe stub outs with plugs.
3. (c) A clean-out with watertight plugs may be installed in lieu of a manhole at the end of a wastewater collection system pipe if no extensions are anticipated.
4. (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).
5. (e) A manhole must be made of monolithic, cast-in-place concrete, fiberglass, pre-cast concrete, high-density polyethylene, or equivalent material that provides adequate structural integrity.
6. (f) The use of bricks to adjust a manhole cover to grade or construct a manhole is prohibited.
7. (g) Manholes may be spaced no further apart than the distances specified in the following table for a wastewater collection system with straight alignment and uniform grades, unless a variance based on the availability of cleaning equipment that is capable of servicing greater distances is granted by the executive director.
   Attached Graphic
   
8. (h) Tunnels are exempt from manhole spacing requirements because of construction constraints.
9. (i) An intersection of three or more collection pipes must have a manhole.
10. (j) A manhole must not be located in the flow path of a watercourse, or in an area where ponding of surface water is probable.
11. (k) 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.

12. (l) Manholes must meet the following requirements for covers, inlets, and bases.

    1. (1) Manhole Covers.

       1. (A) A manhole where personnel entry is anticipated requires at least a 30 inch diameter clear opening.
       2. (B) A manhole located within a 100-year flood plain must have a means of preventing inflow.
       3. (C) A manhole cover construction must be constructed of impervious material.
       4. (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.

    2. (2) Manhole Inverts.

       1. (A) The bottom of a manhole must contain a U-shaped channel that is a smooth continuation of the inlet and outlet pipes.
       2. (B) A manhole connected to a pipe less than 15 inches in diameter must have a channel depth equal to at least half the largest pipe's diameter.
       3. (C) A manhole connected to a pipe 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.
       4. (D) A manhole connected to a pipe greater than 24 inches in diameter must have a channel depth equal to at least the largest pipe's diameter.
       5. (E) A manhole with pipes of different sizes must have the tops of the pipes at the same elevation and flow channels in the invert sloped on an even slope from pipe to pipe.
       6. (F) A bench provided above a channel must slope at a minimum of 0.5 inch per foot.
       7. (G) An invert must be filleted to prevent solids from being deposited if a wastewater collection system pipe enters a manhole higher than 24 inches above a manhole invert.
       8. (H) A wastewater collection system pipe entering a manhole more than 24 inches above an invert must have a drop pipe.
13. (m) The inclusion of steps in a manhole is prohibited.
14. (n) 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.

15. (o) Venting. An owner must use an alternate means of venting if manholes are at more than 1,500 foot intervals and gasketed manhole covers are required for more than three manholes in sequence. Vents must meet the following requirements:

    1. (1) Vent design must minimize inflow;
    2. (2) Vents must be located above a 100-year flood event elevation; and
    3. (3) Tunnels must be vented in compliance with this subsection.
16. (p) Cleanouts. The size of a cleanout must be equal to the size of the wastewater collection system main.

Source Note:The provisions of this §217.55 adopted to be effective August 28, 2008, 33 TexReg 6843.