A.
General. All pipe used for storm drainage shall be either Class IV
reinforced concrete pipe (RCP) or high-density corrugated polyethylene
smooth interior pipe (CPEP).
B.
Minimum cover. The minimum cover over all storm drainage located
within the right-of-way shall be two feet. Where conflicts with other
subsurface facilities occur, and with approval of the Board of Selectmen
or the Town Engineer, pipe may have as little as 18 inches of cover,
but in such cases extra-strength Class V RCP shall be used with a
crushed stone bedding extending to a minimum depth of four feet below
finished grade.
C.
Slotted or perforated storm drains. Where water is encountered in the pipe trenches, or where underdrains are required under § 187-57, storm drains shall either be slotted RCP or perforated high-density corrugated polyethylene smooth interior pipe.
D.
Additional underdrains. Where additional underdrains are deemed necessary
in locations not requiring other storm drainage, perforated high-density
corrugated polyethylene smooth interior pipe with a minimum internal
diameter of six inches shall be used.
E.
Materials and methods. Except as noted herein, construction methods
shall conform to the State Standard Specifications for Culverts and
Underdrain and Outlets. Where high-density corrugated polyethylene
smooth interior pipe is used for storm drains, it shall be installed
in a Type II installation shown in the Standard Detail Drawings, regardless
of the internal pipe diameter, with backfill material conforming to
the State Standard Specifications Section M.08-01-21. Where reinforced
concrete pipe is used for storm drains, it shall be installed in a
Type II installation with backfill material conforming to the State
Standard Specifications Section M.02.06 (Grading A). For underdrains,
pipe shall be installed with holes in a downward position. Aggregate
used for backfilling around underdrains and slotted or perforated
pipe shall conform to the State Standard Specifications Section M.08.03-1
(No. 8 crushed stone). Sand shall not be permitted as backfill around
underdrains. Geotextile fabric, conforming to the State Standard Specification
Section M.08.01-26, shall be wrapped around the aggregate as shown
in the Standard Detail Drawings. Reinforced concrete pipe shall conform
to the State Standard Specifications Section M.08.01-6, or Section
M.08.0-10 for slotted reinforced concrete pipe. Material used for
sealing joints in concrete pipe shall conform to the State Standard
Specifications for Cold-Applied Bituminous Sealer (Section M.08.01-18),
or Pre-formed Plastic Gaskets (Section M.08.09.19). High-density corrugated
polyethylene smooth interior pipe shall conform to the AASHTO Standard
Specifications M 294 Type S, or M 294 Type SP/M 252 Type SP for perforated
high-density corrugated polyethylene smooth interior pipe.
A.
General. Catch basins and manholes shall be precast reinforced concrete
constructed in accordance with the Connecticut Department of Transportation
Standard Sheets.
B.
Materials and methods. Except as noted herein, all materials and
construction methods shall conform to the requirements of the State
Standard Specifications for Catch Basins, Manholes and Drop Inlets.
All catch basin and manhole structures shall be of precast reinforced
concrete construction. Use of brick, concrete building brick or masonry
concrete units shall not be permitted unless otherwise approved by
the Board of Selectmen or the Town Engineer. However, a course of
brick or concrete building brick may be permitted to allow for adjustment
of catch basin tops and manhole frames. In such instances where brick
or concrete brick is permitted, all joints shall be completely filled
with mortar, and the interior and exterior surfaces of the brick shall
be completely covered with a mortar frostproofing. All pipe penetrations
shall be cut flush with the inside walls and shall be bricked and
mortared inside and outside of all catch basin and manhole structures.
All catch basin frames and grates shall be 507K - Type A, constructed
of galvanized steel. Manhole frames and covers shall be heavy-traffic
duty, constructed of cast iron. Frames shall have a twenty-four-inch
internal opening. Covers shall be marked "STORM." Where required by
the Board of Selectmen or the Town Engineer, covers shall be bolted.
A.
General. Flared end sections and headwalls shall be constructed in
accordance with the Connecticut Department of Transportation Standard
Sheets.
B.
Materials and methods. All materials and construction methods shall
conform to the State Standard Specifications for Culvert Ends and
Retaining Walls, Endwalls and Steps. When high-density corrugated
polyethylene smooth interior pipe is used, and culvert ends are specified,
they shall be metal culvert ends. High-density polyethylene culvert
ends shall not be permitted.
A.
General. Stone for this work shall be of the size, and placed to
the limits and depth, specified on the drawings.
B.
Materials and methods. Construction methods shall conform to the
requirements of the State Standard Specifications for Riprap, and
materials shall conform to the requirements of the State Standard
Specification Section M.12.02. Where geotextile fabric is specified
underneath riprap, it shall conform to the requirements of the State
Standard Specification Section M.08.01-26.
A.
General. Open channels shall be stabilized with riprap, sod, or seed
protected with turf reinforcement mats. When conditions are such that
lining of the open channel with riprap is necessary to prevent erosion,
the size of the riprap shall be no less than intermediate, and the
thickness shall be no less than 18 inches. The method of stabilization
shall be as specified on the drawings.
B.
Materials and methods. For stabilization with riprap, all work shall conform to the requirements specified in § 187-62 above. For stabilization with sod or seed protected with turf reinforcement mats, all materials and methods shall conform to the State Standard Specifications for Sodding and Turf Establishment, respectively.
A.
General. Special structures, including but not limited to bridges, box culverts, retaining walls and stormwater treatment units, shall be designed and constructed in accordance with the most current applicable standards of the Connecticut Department of Transportation, or as otherwise directed by the Board of Selectmen or the Town Engineer. Plans and specifications prepared and sealed by a licensed professional engineer registered in the State of Connecticut who is competent in the field of structural engineering shall be submitted for all special structures. In the case of bridges, such plans and specifications shall be accompanied by a written statement from the design engineer certifying that the bridge has been designed to withstand AASHTO HS20 live loads, and that any waterway opening conforms to the Standards established in § 187-50L of these Design and Construction Standards. Upon completion of construction of any special structure, the licensed professional engineer shall be required to provide a written statement to the Town Engineer that the special structure was constructed in substantial conformance with the approved design drawings and specifications.
B.
Private drain access structure. Where private drain access structures
are required prior to a direct connection to a storm drain, they shall
be fabricated from high-density corrugated polyethylene pipe and fittings
conforming to AASHTO Standard Specification Sections M 294 Type S
and M 252 Type S. The fabrication of the access structures shall conform
to the Standard Detail Drawings, and shall include as a minimum a
standard twelve-inch by twelve-inch by twelve-inch tee with reducers
and couplings as required at each end of the horizontal run, and a
twelve-inch inside diameter vertical riser pipe extending to grade.
A snap-on end cap shall be securely fastened at the end of the vertical
riser pipe, and shall be set flush with the proposed finish grade
elevation.
