[Amended 6-18-1990]
The following design and construction standards
are hereby adopted and made part of the subdivision regulations of
the Town of Wethersfield:
A.
Subdivision plan. A subdivision plan shall be so designated
in the title block and shall be prepared at a scale of one inch equals
40 feet in accordance with Class A-2 requirements of the Code of Recommended
Practice for Standards of Accuracy of Surveys and Maps by the Connecticut
Association of Land Surveyors, Inc., and certified by a registered
land surveyor in the State of Connecticut. The plan shall show two
coordinate ties referenced to the National Geodetic System and shall
contain the following:
(1)
The name of the owner or owners or assignee, subdivider,
North point, scale of map and date and revised dates.
(2)
Boundaries of the subdivision from a boundary survey
conforming to Class D, as set forth by the Connecticut Association
of Land Surveyors, Inc.
(3)
Total acreage of the parcel to the nearest tenth of
an acre.
(4)
Names of abutting property owners and property lines
abutting the subdivision boundaries and proposed street names.
(5)
Indication of zones and zone boundary lines.
(6)
Topography, flow line of watercourses and existing
structures and culverts.
(7)
Layout of existing and new streets, buildings and
lots, public open spaces, easements and encroachment lines with approximate
dimensions.
(8)
Proposals for furnishing improvements and utilities.
(9)
In land of difficult topography, where most of the
lots are to be developed by the subdivider, a preliminary site grading
plan may be required.
(10)
Where sewage disposal is proposed through septic
tanks, seepage and groundwater tests shall be made to the satisfaction
of the Director of Health, whose report thereon shall be submitted
with the preliminary study.
(12)
A key map at a scale of one inch equaling not
more than 200 feet shall show the street or streets giving access
to the subdivision extending to the intersections of at least two
other streets.
(13)
Layout of streets to be constructed with accurate
placement of merestones at all PT (point of tangency) and PC (point
of curvature) points and within sight of the next nearest merestone.
The merestone is to be set in accordance with Class A-2 of the Connecticut
Association of Land Surveyors, Inc., and under the direction of a
Connecticut registered land surveyor. Merestones shall be supplied
by the Town of Wethersfield at the developer's expense.
(14)
Street names.
(15)
All easements, rights-of-way and encroachment
lines.
(16)
Building lines on all lots and side and rear
yard lines on odd-shaped lots. On curved streets, the chord distance
of the building line (front yard) shall be shown.
(17)
When more than one sheet is required, a key
map of the entire subdivision shall be included on each sheet.
B.
The subdivider shall provide that all maps which show
horizontal and vertical dimensions data and the design of street patterns
and lot layouts and the staking of such data in the field shall be
performed by a land surveyor registered in Connecticut. The design
of public improvements and utilities shall be performed by a professional
engineer registered in Connecticut, and such professional engineer
shall:
(1)
Supervise construction of all improvements and utilities
shown on such plans; and
(2)
Submit for approval to the Engineering Division an
as-built drawing upon completion of all public improvements. This
plan shall be on a 0.003-mil Mylar and certified by a Connecticut
registered land surveyor. Certification shall show the public utility
improvements in substantial agreement with the approved public utility
improvement plans.
C.
The public utilities and improvements plan shall contain:
(1)
The name of the owner or owners or assignee, subdivider,
North point, scale of map, and date and revised dates.
(2)
Boundaries of the subdivision from a boundary survey
conforming to Class D, as set forth by the Connecticut Association
of Land Surveyors, Inc.
(3)
Total acreage of the parcel to the nearest tenth of
an acre.
(4)
Names of abutting property owners and property lines
abutting the subdivision boundaries and proposed street names.
(5)
Indication of zones and zone boundary lines.
(6)
Topography, flow line of watercourses and existing
structures and culverts.
(7)
Layout of existing and new streets, buildings and
lots, public open spaces, easements and encroachment lines with approximate
dimensions.
(8)
Proposals for furnishing improvements and utilities.
(9)
In land of difficult topography, where most of the
lots are to be developed by the subdivider, a preliminary site grading
plan may be required.
(10)
Where sewage disposal is proposed through septic
tanks, seepage and groundwater tests shall be made to the satisfaction
of the Director of Health, whose report thereon shall be submitted
with the preliminary study.
(12)
A key map at a scale of one inch equaling not
more than 200 feet shall show the street or streets giving access
to the subdivision extending to the intersections of at least two
other streets.
(13)
Plan-profile map or maps showing all streets
to be constructed with stations every 50 feet, curve data with vertical
curve stations every 25 feet, widths of right-of-way paving and sidewalks
where required. Where required, in the judgment of the Engineering
Division, street intersections shall be developed at a larger scale,
showing catch basins, gutter, road center line, curb and sidewalk
elevations.
(14)
Plan-profile maps may also show all utility lines, encroachment lines and all easements for utilities, drainage, walks and other rights-of-way with location, size and inverts of existing and new culverts or the entire drainage system, except for detail required in § 143-41C(13) above, may be shown on a separate map at a scale of one inch equaling not more than 40 feet.
(15)
Drainage analysis map shall show the tributary
watershed area and downstream area affected by runoff. Drainage computations
shall consider the entire watershed area and criteria and computations
used in determining pipe sizes shall be submitted in writing.
(16)
When a site grading plan is required by the
Commission, such plan shall become part of the public utilities and
improvement plan.
A.
All streets shown on the public utilities and improvements
plan shall be constructed in conformance with standard cross sections
of the Engineering Division of the Town.
B.
Streets grades at the center line shall not exceed
7% for primary streets nor 10% for residential streets. No street
grades shall be less than 1% except in a specific case where the Engineering
Division agrees that there is practical difficulty, in which case
grades not less than 0.5% may be permitted.
C.
Street specifications.
(1)
Road pavements shall be constructed in accordance
with specifications of the State of Connecticut Department of Transportation.
(2)
Subbase gravel: six inches or more thick after compaction
(if required by the engineering division).
(3)
Base course: eight inches processed stone applied
in two courses four inches thick after compaction, well-keyed and
dry-bound, and two inches bituminous concrete binder.
(4)
Surface: two inches dense graded bituminous concrete
pavement.
D.
Branch offsets for all underground services to be
individual parcels shall be extended by the developer beyond the street
right-of-way lines prior to installation of the bituminous surface
course.
E.
Bituminous concrete curbs shall be constructed on
both sides of all streets in accordance with the Design and Construction
Standards for Public Improvements, Wethersfield, Connecticut. Wherever
possible, curb cuts for driveways shall be formed as the bituminous
lip is installed.
F.
Gutters and shoulders shall be formed as a continuation
of street paving, as shown on typical cross-section sheets.
G.
Sidewalks, where required, shall be portland cement
concrete, as shown on the standard details of the Engineering Division
and in accordance with the sidewalk specifications of the Town of
Wethersfield. Pedestrian access ramps are to be installed at all intersecting
streets as shown on the detail typical intersection. Ramps are to
be portland cement concrete and shall not have a slope greater than
one foot rise in 12 feet, or 8.33%, unless otherwise approved by the
Town Engineer.
H.
All of the area which is not covered by sidewalk or
pavement within the street right-of-way shall be graded, loamed and
seeded in conformance with Form 811 and amendments thereto of the
Connecticut State Highway Department specifications.
A.
A complete system of storm drainage shall be constructed
in accordance with the best standard practice and in accordance with
the typical standard details of the Engineering Division and the following
design criteria:
(1)
Design storm (return frequency):
(2)
Time of concentration shall be computed on the sum
of overland flow time (sheet flow), plus time in swales and gutters,
plus time in pipes (pipes assumed flowing full), with minimum of 10
minutes to be used for storm sewer design.
(3)
Runoff factors:
(a)
Areas containing pavement, sidewalks and roofs:
90%. Areas containing lawns and natural ground: 15% to 30%, depending
on the slope of the ground.
(b)
Weighted runoff factors are to be used in drainage
computations. Runoff factors for adjacent undeveloped land are to
be based on ultimate development of the land in accordance with existing
zoning and the Table of Weight and Runoff Factors.
|
Table of Runoff Factors
| |
|---|---|
|
Types of Terrain
|
Value C
|
|
Impervious surfaces
|
0.90-0.95
|
|
Steep barren surfaces
|
0.80-0.90
|
|
Rolling barren surfaces
|
0.60-0.80
|
|
Flat barren surfaces
|
0.50-0.70
|
|
Rolling meadow
|
0.40-0.65
|
|
Deciduous timberland
|
0.35-0.60
|
|
Conifer timberland
|
0.25-0.50
|
|
Orchard
|
0.15-0.40
|
|
Rolling farmland
|
0.15-0.40
|
|
Flat farmland
|
0.10-0.30
|
|
Table of Runoff Factors
| |
|---|---|
|
Types of Surface
|
Value C
|
|
Watertight surfaces such as roofs and pavements
|
0.70-0.90
|
|
Block pavements with open joints
|
0.50-0.70
|
|
Macadam pavements
|
0.25-0.60
|
|
Gravel surfaces
|
0.15-0.30
|
|
Parks, cultivated lands, lawns, etc., depending
on slopes and character of soil
|
0.50-0.30
|
|
Wooded areas
|
0.01-0.20
|
(4)
Design method: The Rational Method shall be used,
where "Q" equals "Air."
B.
Storm sewer design.
(1)
Minimum size pipe: 15 inches' diameter.
(3)
Minimum slope shall be sufficient to provide velocity
of two feet per second when flowing 1/4 full:
|
Size
(inches)
|
RCP
(n = 0.015)
|
RCP
(n = 0.013)
|
ACCMP
(n = 0.021)
|
|---|---|---|---|
|
12
|
0.0054
|
0.0110
| |
|
15
|
0.0040
|
0.0080
| |
|
18
|
0.0032
|
0.0060
| |
|
21
|
0.0025
|
0.0050
| |
|
24
|
0.0021
|
0.0042
| |
|
30
|
0.0012
|
0.0031
| |
|
36
|
0.00095
|
0.0024
| |
|
42
|
0.00075
|
0.0019
| |
|
48
|
0.00062
|
0.0018
| |
|
54
|
0.00053
|
0.0014
| |
|
60
|
0.00045
|
0.0012
| |
|
72
|
0.00035
|
0.00098
|
(5)
All reinforced concrete pipe (RCP) shall have gaskets.
All trenches shall be covered with six-mil (0.006 inch) polyethylene
wrap.
