All standards in these regulations shall be
considered minimum standards, and may be varied from or waived where
the Board considers that alternate conditions will serve substantially
the same objective. A written explanation of all waivers shall be
maintained in the files, with the reasons therefor.
A.
Location and alignment.
(1)
All streets in the subdivision shall be designed so
that, in the opinion of the Board, they will provide safe vehicular
travel. Due consideration shall also be given to the following features:
(a)
Volume of cut and fill;
(b)
Area over which existing vegetation will be
disturbed, especially if within 200 feet of a river, wetland or water
body, or in areas having a slope of more than 15%;
(c)
Extent of waterways or wetlands altered or relocated;
(d)
Dimensions of paved areas (including streets)
except as necessary for safety and convenience, especially in aquifer/recharge
areas;
(e)
Use of collector streets to avoid traffic on
streets providing house frontages;
(f)
Visual prominence of natural features of the
landscape;
(g)
Maintenance within the subdivision of runoff
and vegetative cover equivalent to conditions before development.
(2)
The proposed streets shall conform to the Master Plan
as adopted by the Board.
(3)
Provision satisfactory to the Board shall be made
for the proper projection of streets, or for access to adjoining property
which is not yet subdivided.
(4)
Reserve strips prohibiting access to streets or adjoining
property shall not be permitted, except where, in the opinion of the
Board, such strips shall be in the public interest.
(5)
Access to arterial street. Intersections of collector
and residential streets with arterial streets will not normally be
allowed at intervals of less than 450 feet. Subdivisions of 50 or
more lots will be required to have more than one access to an existing
arterial street or to a proposed arterial street which is to be built
in conjunction with the proposed subdivision.
(6)
Street jogs. Street jogs in arterial and collector
streets with center-line offsets of less than 500 feet shall not be
allowed. Street jogs in minor roads with center-line offsets of less
than 125 feet should be avoided.
(7)
The minimum center-line radii of curved streets shall
be 100 feet for minor roads. One hundred and fifty feet shall be required
for collector streets.
(8)
Streets shall be laid out so as to intersect as nearly
as possible at right angles. No street shall intersect any other street
at less than 60°.
(9)
Property lines at street intersections shall be rounded
or cut back to provide for a curb radius of not less than 25 feet.
(10)
Visibility from center line of a street shall
never be less than 200 feet or as dedicated by a posted speed limit.
(11)
Access through another municipality. In case
access to a subdivision crosses land in another municipality, the
Board may require certification by the appropriate officials that
such access is in accordance with the zoning and subdivision requirements
of such municipality, and that a legally adequate performance bond
has been duly posted, and that such access is adequately improved
to handle prospective traffic. As well, lot lines should be laid out
so as not to crowd municipal boundary lines.
(12)
Streets shall be continuous and in alignment
with existing streets and shall be at least 200 feet apart at intersection
with collector.
B.
Width.
(1)
The minimum width for two-way, paved residential streets
shall be as follows:
|
Streets
|
Street Pavement Width
|
Right-of-Way Width
|
|---|---|---|
|
Minor roads and streets
|
20 feet
|
40 feet
|
|
Secondary collector
|
26 feet
|
50 feet
|
|
Primary collector
|
36 feet
|
50 feet
|
|
Arterial
|
As per State Highway Department design standards
|
As per State Highway design standards
|
(2)
Greater width shall be required by the Board when
deemed necessary for present and future vehicular travel or on-street
parking.
(3)
The minimum width may be reduced if approved by the
Town Planning Board for the following reasons:
(a)
The reduction in width is complemented by enforceable
parking regulations for streets where widths are reduced.
(b)
Reductions which are a part of an overall drainage
plan to reduce the impervious surfaces in the subdivision and reduce
runoff from the parcel shall be permitted if plans for safety, parking,
pedestrian circulation and other factors are deemed adequate by the
Planning Board to accommodate the requested reductions.
(4)
The minimum one-way width for each direction of a
paired system shall be 18 feet. The minimum width for a one-way loop
street shall be 18 feet.
C.
Grade. Grades of streets shall not be less than 1%.
Grades shall not be more than 6.0% for primary collector streets,
nor more than 12.0% for secondary collector streets, minor roads or
streets.
D.
Dead-end streets/culs-de-sac.
(1)
The length of a cul-de-sac shall not exceed 500 feet
unless a greater length is deemed desirable by the Planning Board
because of topography or other local conditions;
(2)
Every dead-end street shall have a turnaround designed
to accommodate vehicles. A circular turnaround shall have an outside
roadway diameter of at least 100 feet, and a property line diameter
of 130 feet.
A.
Easements for utilities across lots or centered on
rear or side lot lines shall be provided where necessary.
B.
Where a subdivision is traversed by a watercourse,
drainageway, channel or stream, the Board may require that there be
provided a stormwater easement or drainage right-of-way of adequate
width to conform substantially to the lines of such watercourse, drainageway,
channel or stream, and to provide for construction or other necessary
purposes. In no case shall the width be less than 20 feet, or the
side slope be steeper than two horizontal, or one vertical.
C.
Access easements or parcels to adjacent property shall
be provided, if required by the Board, for use by emergency vehicles
and for the benefit of the town. They shall be a minimum width of
20 feet. Bikeways or walkways may satisfy this requirement.
D.
Slopes adjacent to roadways, natural or man-made,
may be placed within easements on individual properties rather than
acquired as rights-of-way.
E.
Lots shall be prepared and graded consistent with
drainage into the subdivision, and in such manner that development
of one shall not cause detrimental drainage on another or on areas
outside the subdivision, to the extent permitted by law. If provision
is necessary to carry drainage to or across a lot, an easement or
drainage right-of-way of a minimum width of 20 feet and proper slope
shall be provided.
The Board may require the plan to show a park
or parks, suitably located for playground or recreation purposes,
or for providing light and air. The park or parks shall not be unreasonable
in area in relation to the land being subdivided, and to the prospective
uses of such land, and shall be at least equal to one acre of land
for each 20 single-family dwelling units or fraction thereof shown
on the plan, but not less than 6% of the gross area of the subdivision.
Each area reserved for such purpose shall be of suitable area, dimensions,
topography and natural character for the purpose of a park and/or
playground. The area or areas shall be so located as to serve adequately
all parts of the subdivision as approved by the Board. The Board may
require that the area or areas reserved shall be located and laid
out so as to be used in conjunction with similar areas of adjoining
subdivisions or of probable subdivisions.
All natural features, such as trees, wooded
areas, watercourses, scenic points and historic spots, shall be preserved
as much as possible. Any clearance, backfilling, cutting, thinning
or other disturbance to trees six inches or over in diameter, measured
four feet above finished ground level (dbh), located within the unpaved
portions of the right-of-way, or other natural vegetation shall be
prohibited unless deemed proper by the Board after a site inspection.
Any such proposed clearance shall be shown on the plan, and written
reasons therefor may be requested by the Board. Tree wells or retaining
walls shall be of such design to meet the standards as set forth in
the Tree Experts Manual, or some similar publication.
In order to reduce erosion accompanying the
installation of ways, utilities and drainage, and the resultant pollution
of streams, wetlands and natural drainage areas, the applicant shall
submit a sediment control plan, including control methods such as
berms, dikes, detention ponds, mulching and temporary sodding.
A.
Street drainage utilizing curbs and gutters shall
be designed to keep the velocity of the flow of water in the gutter
below levels which are hazardous to pedestrian safety.
B.
Storm drains, culverts, and related facilities shall
be designed to permit the unimpeded flow of all natural watercourses,
to ensure adequate drainage at all low points along streets, to control
erosion, and to intercept stormwater runoff along streets at intervals
reasonably related to the extent and grade of the area being drained.
To the maximum extent feasible, stormwater shall be recharged rather
than piped to surface water.
C.
New drainage systems shall be properly connected to
any existing drains in adjacent streets or easements which may exist.
Where no adequate drainage system exists, or where it is inadequate,
it shall be the responsibility of the subdivider to extend his system
outside the subdivision in a manner specified or approved by the Board
to dispose properly of all the drainage from the proposed subdivision.
D.
When the subdivision causes a requirement for drainage
improvements outside its area, the subdivider shall be required to
secure the necessary approvals and provide such improvements in the
public interest.
E.
Where the adjacent property is not subdivided, adequate
provision shall be made for the extension of the drainage system beyond
the boundaries of the subdivision, and for it to carry the additional
load that may be placed on the system. This shall be done by providing
drains of adequate size and at proper slopes as specified by the Planning
Board in order to permit their extension to the boundaries, and the
proper connection of those of future subdivisions in the adjacent
area.
F.
Storm drains and culverts shall be a minimum of 12
inches inside diameter, and shall be greater when required by the
Board. The proper drain size may be calculated by using Manning's
Formula with a kutter's "n" value of .013 for concrete pipe and .024
for corrugated metal pipe.
G.
All storm drains shall be reinforced concrete of adequate
strength except that in off-street locations bituminous coated, galvanized,
corrugated metal pipe or pipe arch may be used if approved by the
Board. Concrete pipe shall conform to the State of Massachusetts'
Standard Specifications for Highways and Bridges, as amended.
H.
Water velocities in pipes and gutters shall be between
two and 10 feet per second, and not more than five feet per second
on ground surfaces. All undeveloped tributary areas shall be assumed
to be fully developed in accordance with the Zoning Bylaw.[1] Consideration will be given to flatter slopes if adequate
provisions are made for cleaning the pipes. All plans having drains
with slopes which will produce pipe velocities less than two feet
per second, flowing full, shall be accompanied by a letter stating
the reason for the flat slope. The letter shall have a space for approval
by the Planning Board or its agent, and the drain shall not be constructed
until the letter has been approved.
I.
Catch basins shall be installed on both sides of the
roadway on continuous grades at intervals not to exceed 300 feet,
at low points and sags in the roadway, near the corners of the roadway
at intersecting streets, and at other locations as required by the
Board. Such catch basins shall be provided with granite headers with
storm inlets. Drain pipes may extend through an adjacent catch basin
and, thereafter, through manholes to the point of discharge, with
a manhole being required at every change in direction, slope or diameter
in the drain pipes. All catch basins, except for the first two, shall
discharge into the drain through a manhole. Any catch basins and manholes
used shall be at least six feet deep and four feet in diameter (inside
measurements), with a thirty-inch or greater sump below pipe invert,
and shall be constructed of concrete blocks or precast concrete units.
Manhole covers and grates shall be in conformance with Massachusetts
DPW Specifications, designed and placed so as to cause no hazard to
bicycles.
J.
Inlets shall have an adequate waterway opening to
pass the design storm with not more than 0.2 feet of surcharge. Grates
and frames shall be cast iron suitable for the loads which can occur
either during the construction or afterward. Inlets shall be constructed
either of brick and mortar with eight-inch-thick walls, precast segmental
concrete blocks not less than six-inch-thick mortared in place, or
of precast pipe sections. Inlets shall be set on a base of either
poured concrete eight inches in thickness, or precast segmental base
blocks not less than four inches in thickness. Inlets shall be used
in off-street locations, and the grate frame shall be mortared in
position with the top 0.2 feet below the grade of the finished ground
surface. Side openings may be used in lieu of a grate if the quantity
of runoff exceeds the capacity of a grate of reasonable size, as approved
by the Planning Board or its agent. Inlets shall be 4.0 feet inside
diameter below the corbelling, and shall not be used on drains greater
than 30 inches in diameter. A shaped invert is not required, but the
bottom of the inlet shall be finished at the same grade as the lowest
pipe invert. At inlets where the outlet pipe is larger than the inlet
pipe, the crown of the outlet pipe shall be at the same elevation
or lower than the crown of the inlet pipe.
K.
A design analysis shall be submitted with each definitive
plan submitted for approval. The design analysis shall include at
least the following information:
(1)
Storm drainage system. The data shall include consideration
of the entire watershed, and the calculations used in designing the
drainage system including area calculations, intensity of rainfall,
coefficient of runoff, time of concentration, discharge, pipe coefficients
of roughness and quantity and velocity of flow under design conditions.
(2)
Storm sewers shall be based on a ten-year frequency
storm, retention basins on twenty-five-year, and culverts shall be
based on a fifty-year frequency storm, with consideration given to
damage avoidance for a one-hundred-year storm.
(3)
Any areas designated as drainage areas shall be tested
for adequate percolation.
L.
Retention basins or other means shall be provided
to control the rate of runoff at the property lines from a twenty-five-year
storm after development to the predevelopment level.
A.
Curbing shall be installed as required by the Planning
Board, and may consist of granite bituminous concrete, Portland cement
or other materials, depending upon factors of safety, convenience
and cost.
A.
Where adjacent property is not subdivided, or where
all the property of the applicant is not being subdivided at the same
time, and the expense is deemed reasonable by the Board, provision
shall be made for the extension of the utility system by continuing
the mains the full length of streets and to the exterior limits of
the subdivision at such grade and size which will, in the opinion
of the Board, permit their proper extension at a later date.
B.
Sanitary sewers.
(1)
No portion of sewerage system shall be approved if
a requires a connection to municipal system over land of other owners
unless appropriate easements are first obtained.
(2)
The calculations used in designing the sewerage system
including the method of estimating average flows (including infiltration
allowances), the peaking factor used, the hydraulic design of the
system including quantity and velocity of flow under both average
and peak flow conditions shall be included.
(3)
Sanitary sewers, including all appurtenances, shall
be designed to serve as many lots in a subdivision as possible, and
to provide connection to municipal sewerage system, as approved by
the Sewer Commissioners.
(4)
Minimum sewer pipe size shall be eight inches, and
sanitary sewers shall be such as to ensure the flow of not less than
two feet per second, nor more than 10 feet per second, except that
house connections shall be at least six inches in diameter and shall
pitch up towards the lot at least 3/16 inches per foot.
(5)
Manholes shall be no more than 300 feet apart.
C.
Water supply.
(1)
Water mains, laterals and appurtenances shall be of
the size, material and location as directed by the Water Commissioners.
(2)
Hydrants, with valves of a type approved by the Chief
of the Fire Department and the Water Commissioners, shall be installed
on all water mains at a spacing of not more than 500 feet. In addition,
there shall be a hydrant or blowoff and valve placed at the end of
every water main, as directed by the Chief of the Fire Department
or the Water Commissioners.
D.
Streetlighting shall be installed as required by the
Board.
E.
Fire alarm boxes shall be installed as directed by
the Chief of the Fire Department. The applicant shall furnish and
install the necessary ducts, fire alarm boxes, and electric cable.
B.
Sidewalks may also be eliminated along one or both
sides of a primary street if the subdivision provides an alternative
pedestrian circulation system. Ordinarily, one sidewalk will be required.
C.
Pedestrian-vehicular separation shall be considered
where possible. Design solutions which achieve this separation shall
receive priority consideration. Planting strips shall be a minimum
of two feet.
D.
Walkways connecting existing trails should be created
wherever reasonable, and developed in new locations.
E.
Paths or sidewalks shall be located within the street
right-of-way. However, horizontal alignment may be varied to minimize
disturbance of land vegetation. If necessary, a sidewalk easement
shall be obtained when the sidewalk goes outside the minimum street
right-of-way.
F.
Sidewalks shall be pitched or sloped towards the roadway
to maximize runoff of water.
G.
Sidewalks shall have a minimum width of four feet.
H.
Sidewalks shall have a maximum grade of 6%, and a
minimum grade of .5%.
