| (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.
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