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.
[1] 
On culs-de-sac and lanes with no on-street parking, the width may be reduced to 18 feet.
[2] 
On a secondary street with on-street parking permitted on one side only, the width may be reduced to 24 feet.
[3] 
On a collector with no on-street parking, the width may be reduced to 26 feet.
(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.
[1]
Editor's Note: See Ch. 140, Zoning.
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.
B. 
Curbs and gutters.
(1) 
Curbs and gutters will be required when they are:
(a) 
Necessary to handle runoff for the section of the roadway to which they are applied.
(b) 
Necessary for the maintenance of the pavement and the prevention of pavement edge reveling.
(c) 
Necessary for safety.
(2) 
Curb and gutter may be eliminated along certain roadways when drainage is provided in swales which are designed to reduce the rate of runoff, restore and/or supply needed water to vegetation in the street right-of-way.
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.
A. 
Sidewalks shall be placed parallel to the roadway(s) providing direct access to:
(1) 
Commercial/retail facilities;
(2) 
Schools;
(3) 
Public recreational facilities; and
(4) 
Elsewhere in accordance with the pedestrian circulation system as necessary.
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%.
Lots, buildings and structures involved in subdivision shall comply with the Town Zoning Bylaw[1] then in effect as varied thereunder.
[1]
Editor's Note: See Ch. 140, Zoning.