Specifications and drawings on Figures 7, 7A,
7B show the minimum acceptable construction for typical catch basins
and curb inlets. Whenever, in the opinion of the Town Highway Superintendent,
ground conditions or other circumstances require larger or heavier
materials and additional materials, reinforcing or other modifications
and improvements in design and construction shall be made as directed
by the Town Highway Superintendent at any time prior to paving.
A. Location. Catch basins shall be located at all points
of change of slope or alignment and at all junction points. Catch
basins shall be located in the lows of sag vertical curves as necessary
to prevent ponding. At no time shall catch basins be spaced farther
apart than 300 feet on slopes up to 6% and 250 feet on slopes over
6% in steepness.
B. Construction. All construction and materials shall
comply with Section 604 of the current Standard Specification of the
State of New York Department of Transportation.
C. Installation of pipes.
(1) Openings in catch basins around all pipes entering
and leaving the basin shall be cut to fit the contours of the pipes
as closely as possible. Remaining intercises shall be solidly filled
with mortar for the full thickness of the wall. Ends of all pipes
shall be cut off flush with the inside surface of the catch basin
walls and shall project outside a sufficient distance to allow for
proper connection with adjoining pipe section.
(2) When the diameter of the effluent pipe is greater
than that of the influent pipe, the elevation of the top of the influent
pipe shall be no lower than the elevation of the top of the effluent
pipe.
(3) When the diameter of the effluent pipe is the same
or smaller than the influent pipe, the elevation of the invert of
the influent pipe shall be no lower than the elevation of the invert
of the effluent pipe. In no case shall the top of any influent pipe
be more than five feet above the invert of the effluent pipe.
D. Curb inlets.
(1) Wherever required, catch basins shall be capped with
inlets having a minimum frame opening of 30 inches by 30 inches or
a type as designated by the Town Superintendent of Highways.
(2) Curb-type inlets shall be installed so that the top
of the grating shall be no more than one inch below the finished grade
of the wearing surface, and the pavement shall be sloped toward the
inlet as shown in Figure 7B. Catch basin covers and cast iron curb boxes shall conform
to the current Standard Specifications of the State of New York Department
of Transportation, Division of Construction, and be designed to carry
H-20 highway loading. All catch basins shall be square unless otherwise
approved by the Town Superintendent of Highways.
E. Steps for catch basins. Catch basins having a depth
greater than 48 inches from the finished surface to the top of the
concrete base shall be provided with steps. The steps shall extend
4 1/2 inches inside the wall of the catch basin. The top step
shall not be more than 18 inches below the finished surface. Intermediate
steps shall be no more than 18 inches apart. Reinforced plastic steps
meeting Section 725-02 of the Standard Specifications, State of New
York Department of Transportation, Construction Division, may be used.