Unless otherwise specified or waived by the Planning Board (upon recommendation by the Planning Board engineer or by the Highway Surveyor), all aspects of roadway construction, including materials and methods of construction, inspections, reporting, etc., shall be in accordance with the specifications of the Massachusetts Department of Transportation in effect at the time of construction.
A.
Clearing, grubbing and excavation.
(1)
The entire area within the right-of-way shall be cleared of all trees, stumps, brush, roots, rocks or boulders and all unsuitable materials. No loam suitable for reuse shall be removed from the subdivision unless adequate loam will remain or is otherwise assured to provide all disturbed areas within the subdivision with a loam depth of at least four inches and also that there is assurance that all streets from which loam is being removed will be brought to subgrade with the approved foundation materials within six months.
(2)
The entire area to be occupied by the roadway, and an additional four feet wider than the paved width or extending outward to the top of slopes in fill areas, shall be excavated a minimum of 15 1/2 inches below finish grade in cut sections or as necessary to remove the topsoil in fill sections. Only areas directly in path of pavement, sidewalks and Cape Cod berms are to be excavated. The Planning Board engineer or his representative may require greater depths of excavation if soft or yielding material detrimental to the subgrade is encountered. All fill or undisturbed material shall be non-frost-susceptible for a minimum depth of three feet below the finished road grade.
(3)
An inspection of this phase of the work will be made when completed.
B.
Gravel base.
(1)
A minimum of 12 inches of clean gravel, approved by the Planning Board engineer, shall be deposited for the full width of the traveled way and shoulders, so as to form a roadway center-line grade, allowing for the pavement thickness, below the proposed finished grade at all points.
(2)
The gravel shall be compacted to 98% of the maximum dry density as determined by the modified Proctor Test in accordance with ASTM 1557, Method "D."
(3)
Gravel shall consist of the following as set forth in the Standard Specifications for Highways and Bridges for the Massachusetts Department of Transportation.
(a)
M1.03.0, Gravel Borrow.
[1]
Gravel borrow shall consist of inert material that is hard, durable stone and coarse sand, free from loam and clay, surface coatings and deleterious materials. Gradation requirements for gravel shall be determined by AASHO-T11 and T27 shall conform to the following:
Sieve | Percent Passing |
|---|---|
1/2 inches | 50% to 85% |
No. 4 | 40% to 85% |
No. 50 | 8% to 28% |
No. 200 | 0 to 8% |
[2]
Maximum size of stone in gravel shall be as follows: three inches largest dimension.
[3]
The following may be considered as alternative specifications only if approval is given by the Planning Board Engineer.
(b)
M1.03.1, Processed gravel for subbase gravel shall consist of inert material that is hard, durable stone and coarse sand, free from loam and clay, surface coatings and deleterious materials. The coarse aggregate shall have a percentage of wear, by the Los Angeles Abrasion Test, of not more than 50.
[1]
The gradation shall meet the following requirements:
Sieve | Percent Passing |
|---|---|
3 inches | 100% |
1 1/2 inches | 70% to 100% |
3/4 inch | 50% to 85% |
No. 4 | 30% to 60% |
No. 200 | 0 to 12% (based on fraction passing No. 4) |
[2]
The approved source of bank run gravel shall be processed by mechanical means. The equipment for producing crushed gravel shall be of adequate size and with sufficient adjustments to produce the desired materials. The processed material shall be stockpiled in such a manner as to minimize segregation of particle sizes. All processed gravel shall come from approved stockpiles.
(c)
M2.01.7, Dense graded crushed stone for subbase.
[1]
This specification covers the quality and gradation requirements for a subbase material combining crushed run coarse aggregates of crushed stone or gravel and fine aggregates of natural sand or stone screenings uniformly mixed with a pre-determined quantity of water.
[2]
Coarse aggregate shall consist of hard, durable particles or fragments of stone or gravel. Materials that break up when alternately frozen and thawed or wetted and dried shall not be used.
[3]
Coarse aggregate shall have a percentage of wear by the Los Angeles Test of not more than 42.
[4]
Fine aggregate shall consist of natural or crushed sand. The composite material shall be free from clay, loam or other plastic material and shall conform to the following grading requirements:
Sieve | Percent Passing |
|---|---|
2 inches | 100% |
1 1/2 inches | 70% to 100% |
3/4 inch | 50% to 85% |
No. 4 | 30% to 55% |
No. 50 | 8% to 24% |
No. 200 | 3% to 10% |
C.
Roadway surface.
(1)
All roadways shall be paved to conform with the finished grade and width as specified, with Class I bituminous concrete paving, Type I-1 in accordance with the standard specifications and subject to the approval of the Planning Board engineer. The applicant shall submit a specification job mix formula to the Planning Board engineer for approval prior to starting work. All material shall conform to the current Standard Specifications for Highways and Bridges for the MassDOT.
(2)
The total thickness of bituminous concrete (compacted) shall be 3 1/2 inches. It shall be applied in two courses: two-inch binder and 1 1/2-inch top course. Spreading and rolling shall also be in conformance with these specifications. Bituminous concrete shall not be placed on muddy or frozen surface. The air temperature must be at least 40° F. and rising.
A.
Underground utilities. All utilities within a subdivision shall be placed underground and shall be shown on the plan. Adequate provisions for streetlighting shall be made where underground electrical service is provided.
B.
Disposal of surface water.
Town Counsel note. The Board should review the impact of controlling so as to require no increase of rate in addition to no increase in volume with a stormwater drainage expert.
(1)
Adequate disposal of surface water shall be provided such that no increase in runoff rate or runoff volume leaves the subdivision. Runoff quality and quantity shall be addressed in accordance with the Massachusetts Department of Environmental Protection Stormwater Management Standards, except as modified in this regulation.
(2)
In order to minimize the maintenance requirements of the subdivision, protect the safety of the inhabitants, and enhance the aesthetics of the completed subdivision, the applicant shall submit a drainage design based on "low-impact design" principles, employing the concepts of "country drainage". Drainage systems shall consist of an integrated series of surface features, such as roadside grassed swales, bioretention areas, infiltration trenches, sheetflow to conserved open space, and constructed wetlands. "Traditional" drainage systems employing catch basins, water quality inlet structures, pipe networks, and detention basins are discouraged and shall only be allowed by waiver if no other alternative exists.
(a)
Stormwater management report. Each drainage plan submitted for approval shall be accompanied by a stormwater management report prepared by a qualified registered professional engineer. The analysis shall follow the requirements of the Stormwater Management Regulations, and any local regulations in effect at the time of submittal. In order to facilitate the employment of the low-impact design principles stated above, the designer may vary from the Stormwater Management Regulations and employ the credits for runoff reduction cited in the Center for Watershed Management Technical Memorandum: The Runoff Reduction Method (4-18-2008 and as revised). All rainfall intensities shall be computed using the Atlas of Precipitation Extremes for the Northeastern United States and Southeastern Canada (the "Cornell Study").
(b)
Design storm. Where a "traditional" drain system has been permitted by waiver, a rainfall having a frequency of occurrence of once in 10 years has been selected for design computations for drain lines. Intensities for small areas correspond to the time of concentration for the area. A rainfall having a frequency of once in 50 years shall be used for roadway culvert design.
(c)
Computation of runoff. Runoff for any area shall be calculated using the Natural Resource Conservation Service TR-55 or TR-20 methodology. The analysis shall assume the development of each lot to the maximum extent permitted by the zoning regulations, unless a restrictive covenant is to be enforced. If the latter, then a copy shall be submitted to the Planning Board along with the Stormwater Management Report.
(d)
Selection of drain size. Where a "traditional" drain system has been permitted by waiver, the proper drain size may be calculated by using "Manning's Formula" with a "Kutter's" "n" value of 0.013 for concrete pipe, and 0.024 for corrugated metal pipe. For culverts less than 30 feet in length and all drains, the minimum size of pipe shall be 12 inches in diameter. The culverts and drains shall be large enough to pass the design storm without surcharge.
(e)
Type of pipe. Where a "traditional" drain system has been permitted by waiver, pipe 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 Planning Board. Concrete pipe shall conform to the Commonwealth of Massachusetts Standard Specifications for Highways and Bridges, as amended.
(f)
Slope of pipe. Where a "traditional" drain system has been permitted by waiver, all pipes shall be laid on a slope so that the minimum velocity with the pipe flowing full shall be 2.0 feet per second. Drain lines shall be laid on a slope of not less than 0.5%. Consideration may be given to flatter slopes if adequate self-cleaning velocity is demonstrated. All plans having drains with slopes which will produce actual velocities less than 2.0 feet per second, excepting catch basin leaders, shall not be permitted. The maximum allowable velocity with the pipe flowing full shall be 10.0 feet per second.
(g)
Inlets. Where a "traditional" drain system has been permitted by waiver, inlets shall have an adequate waterway opening to pass the design storm with not more than 0.2 foot 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 inches 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 0.02 foot 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.
(h)
Catch basins; manholes. Where a "traditional" drain system has been permitted by waiver, 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, and at or near the corners of the roadway at intersecting streets. The Planning Board may require a lesser distance if deemed advisable by the Board because of unusual local conditions. All catch basins must have a three-foot sump and discharge directly into manholes. Basins shall be provided with granite headers containing storm inlets as necessary. (See Detail Plate 4-A.) Manholes shall be required at every change in direction, slope, or diameter in the drainpipe and also at every intersection of drain pipes. (See Detail Plates 1, 1A, 2, 2A, 3, 3A, 3B.)[1]
[1]
Editor's Note: The Details are in Appendix B, included as an attachment to this chapter.
(i)
Excavation. Where a "traditional" drain system has been permitted by waiver, the trench for the pipe shall be excavated to the required line and grade, including earth boulders and ledge. Trenches for storm drains shall be no wider than the outside diameter of the pipe plus 16 inches for pipes through 18 inches nominal diameter, and the outside diameter plus 24 inches for pipes larger than 18 inches. This trench width shall apply from the top of the pipe to the bottom of the trench. Above the top of the pipe the trench may be as necessary to properly install the pipe. Trenches with side slopes steeper than the natural angle of repose of the soil shall be sheeted in an approved manner, as necessary to avoid cave-ins and sloughing. All excavations shall be properly barricaded and lighted at night where they are close to pedestrian or vehicular traffic. Before any pipe is placed in a newly constructed fill, the contractor shall, as directed, place the filling two feet above the top of the pipe, after which the pipe trench may be excavated. If any cross pipes, conduits, drains or other unforeseen obstacles are encountered in the excavation which cannot be relocated, the drain shall be redesigned to avoid the obstruction in a manner suitable to the Planning Board or its agent. Possible obstructions to the line shall be investigated prior to the construction of the drain in its immediate vicinity.
(j)
Bedding. Where a "traditional" drain system has been permitted by waiver, trenches may be excavated with a flat bottom, but the full length of the pipe, except the bell, must rest upon undisturbed soil, except as hereinafter specified. Where trenches have been overexcavated, a flat bottom or gravel foundation, thoroughly compacted, shall be provided for proper pipe bedding. Soil which is considered to be unstable by the Planning Board or its agent shall be removed to a depth of not less than two feet below the bottom of the pipe and replaced with compacted sand and gravel to the bottom of the pipe. Unstable soil or other excavated material shall be disposed of off site as directed by the Planning Board or its agent.
(k)
Pipe laying. Where a "traditional" drain system has been permitted by waiver, pipes shall be laid starting with the downstream end. Grade boards, lasers, or other approved devices shall be provided to insure that the pipe is laid true to line and grade. Reference benchmarks shall be clearly marked to elevations. The joints of all pipes shall be filled with mortar composed of one part Portland cement to three parts clean sharp sand. Lime may be added up to 25% of the cement and enough water to make a workable mix. The downstream pipe shall be laid with groove or bell end facing upstream in the proper position, and a dab of mortar shall be placed in the bell or groove. The spigot or tongue end shall be placed in the bell or groove, such that the inverts match, and the peripheral space shall be filled with stiff mortar. All mortar squeezed out on the inside of the pipe shall be removed before it sets.
(l)
Backfilling. Where a "traditional" drain system has been permitted by waiver, after the pipe has been laid and inspected, the trench shall be backfilled. The space under the pipe haunches shall be carefully filled with selected material, free from stones or frozen earth, and compacted carefully to prevent the pipe from moving. The layer of backfill up to 12 inches over the top of the pipe shall also be selected material free from stones and frozen earth, well compacted. The remainder of the trench shall be backfilled in twelve-inch layers except as noted below, and each layer shall be fully compacted in an approved manner. Under roads or other traffic areas, the trench shall be backfilled in six-inch layers, with each layer compacted to the density of the surrounding soil. Pavement and base course materials removed during the excavation process shall be replaced with pavement and base course to match those removed. When, in the opinion of the Planning Board or its agent, the excavation is deep enough to warrant it, temporary pavement shall be provided as directed. Trenches not in pavement shall be left in a mounded condition as directed by the Planning Board or its agent.
(m)
Security bars. Security bars shall be provided at the entrance and outface of all culverts or open pipe drains. Bars shall be constructed according to the detail indicated on Plate 9 or of a design approved by the Planning Board or its agent, and the grate shall be installed in a manner approved by the Planning Board or its agent. A suitable drawing of the grate and method of installation shall be submitted for approval with the plans for the drains and appurtenances.
(n)
Headwalls. Concrete or field stone masonry headwalls shall be provided at both ends of culverts and the discharge ends of storm drains. They shall conform to the tables on Detail Plate 8 and be placed at a distance of not less than 65 feet from the way line.
(o)
Scour protection. The discharge of all drains shall be protected with a riprap apron of a width not less than 10 times the normal pipe diameter from the end of the discharge pipe. The riprap for exit velocities of 10 feet per second or less shall be composed of a layer of stones 12 inches in thickness or more, placed upon a bed of sand and gravel six inches in thickness. The stones shall be sized so that not less than 60% shall have one dimension 12 inches or more. The stones after being laid shall be carefully chinked by hand to make a reasonable smooth and shaped surface. Where exit velocities are greater than 10 feet per second, the thickness of stones and the dimensions of the individual pieces shall be sized to prevent displacement by the flow. In this case, details shall be submitted to the Planning Board or it agent for approval. In addition, riprap will be required for all drainage channels having design flow velocities greater than five feet per second and for any change in direction or intersection of drainage channels.
A.
General. Two sidewalks shall be required for all minor, major, and secondary streets. Bikeways shall be considered as separate from sidewalks and should be located according to Planning Board recommendations. Where bikeways and sidewalks are adjacent, the minimum right-of-way shall be 25 feet. The profile dimensions and location of separately located sidewalks and bikeways shall be subject to the approval of the Planning Board. The grade shall be at least one inch above curb elevation. Sidewalks and bikeways shall be in accordance with either specification (1) or (2) below:
(1)
Four-inch-thick cement concrete, reinforced with No. 4, four inches by six inches mesh, 3,000-pound concrete, wood float finished, laid on a base of at least six inches of well-compacted bank gravel. An expansion joint (3/4 inch open) shall be provided at least every 20 feet; dividing joints shall be scored into walks every four feet. Base gravel material shall be in accordance with the specifications outlined above for street construction, provided that no stone shall have a dimension in excess of 2 1/2 inches. It shall be thoroughly compacted, using a sidewalk roller weighing at least two tons. (See Detail Plate 4A.[1])
[1]
Editor's Note: The Details are in Appendix B, included as an attachment to this chapter.
(2)
Bituminous concrete. The foundation shall be eight inches of bank gravel as specified in Subsection A(1) above (material and compaction). The wearing surface shall be laid in two courses, a 1-1/2-inch binder course and a one-inch top course, the thickness to be measured after compaction. The material and application shall conform to the specifications for roadway surfacing. All edges of the walks shall be formed with wood screeds which are securely anchored and left in place. (See Detail Plate 4A.[2])
[2]
Editor's Note: The Details are in Appendix B, included as an attachment to this chapter.
B.
Design standards. The following design guidelines shall be observed during the design and construction of bikeways:
(1)
Minimum pavement width: 10 feet.
(2)
Maximum gradient: 5%.
(3)
Minimum center-line radius: 25 feet.
(4)
Vertical curves shall be required for changes in grade which exceed 1%.
(5)
Curb cuts shall be provided at the intersection of bikeways and streets.
(6)
Signs of a design approved by the Board shall clearly mark each "Bikeway."
A.
General. Curbing is not required where the subdivision is designed incorporating roadside swales as part of a "country drainage" system. When a waiver is granted for a "traditional" drainage system, it is required where needed to contain runoff and shall be one of the types specified under Subsection B as determined by the Planning Board, except that granite curb shall be used in the following cases:
(1)
All finished grades over 6%: vertical granite. Granite curbing will be required on both sides of the roadway in this case.
(2)
All headers for catch basins: vertical granite.
(3)
All street intersections along turning radii and extending six feet tangent along each side of each roadway at the intersection.
(4)
Approved types of curbing:[1]
[1]
Editor's Note: The Details are in Appendix B, included as an attachment to this chapter.
(5)
Terminal curb section. A tapered terminal curb section of vertical granite curb construction having a minimum length of four feet and a tapered section two feet in length will be required as the first and last stones along each section of granite curbing and adjacent to each separately placed curb inlet.
B.
Where a "traditional" drain system has been permitted by waiver, Cape Cod berms will be required on all cul-de-sacs and in other locations as specified by the Planning Board. Berm shall consist of Class I bituminous concrete, Type I-1, and shall conform to the requirements for either top course or dense mix. All berms shall be placed over a suitable foundation for support. (See Detail Plate 5A.[2])
[2]
Editor's Note: The Details are in Appendix B, included as an attachment to this chapter.
The area in back of the sidewalk shall be sloped at the rate of three to one (maximum) to a point where it precisely coincides with the finished grade of abutting lots, except as required to facilitate "country drainage".
A.
On all areas within roadway, walkway, and bikeway rights-of-way, except areas not receiving treatment or areas requested by the Planning Board to be left in a "natural condition", the ground shall be cleared and grubbed and at least six inches of an approved loam topsoil shall be applied. These areas shall be protected from erosion and seeded with an acceptable perennial lawn grass or other approved ground cover. Planted areas will not be accepted until there is a substantial, uniform, and healthy growth for a period of not less than two years and until building construction has been completed. This portion of the passbook account will be held for this period in an amount to be determined by the Planning Board and the Town Engineer.
B.
A six-inch thickness of loam shall be provided throughout the entire disturbed area of all lots and on the planting strips along the roadway. Only such areas as roadway, driveways, building sites and areas requiring filling may be stripped of topsoil. Areas on a lot where cut or fill is not required for construction of the buildings on that lot shall not be stripped of topsoil.
A.
Monuments shall be installed at all street intersections, at all points of change in direction or curvature of streets and at other points where, in the opinion of the Planning Board, permanent monuments are necessary. Such monuments shall be at least five inches by five inches reinforced concrete or granite posts and must extend to not more than four inches above finished ground unless otherwise specifically authorized by the Planning Board in writing.
B.
No permanent monuments shall be installed until all construction which could destroy or disturb the monuments is completed.
A.
Existing trees which, in the opinion of the Planning Board, are suitable for street trees shall be maintained and left as such. Where trees are inadequate, new trees of at least two-inch caliper measured at a height of 42 inches from the ground and at least 12 feet in height shall be planted. All trees shall be planted within the right-of-way at a distance not to exceed 30 feet. The species and variety of the trees shall be selected and approved by the Tree Warden. No evergreen trees such as fir, pine, hemlock or spruce shall be planted along the way. No trees shall be planted at any intersection so as to obstruct vision of safe vehicle traffic. All planted trees shall be planted in 1/2 cubic yard of loam, mulched with four inches of wood chips and guyed in a manner to ensure their survival. Developer shall warrantee all planted trees for two years as determined by the Tree Warden.
B.
Every effort shall be made to maintain existing stone walls and significant trees within the subdivision. Significant trees are any tree (excepting white pine) with a girth of 16 inches or greater at forty-eight-inch height. All existing stone walls and significant trees shall be field located and shown on the subdivision plan, and a notation made as to whether they will remain or be disturbed. There shall be no disturbance greater than 20% of either significant trees or stone walls.
The developer shall furnish and erect necessary signs to designate the name of each street in his development. Said signs shall conform with those used by the Town.
The developer shall be responsible for furnishing and erecting streetlights at location approved by the Planning Board and the Board of Selectmen. Any such streetlights shall meet the requirements of the Lighting Bylaw. Use of lampposts on each lot is encouraged.
In recognition that no municipal water system is present to provide hydrants convenient to the proposed subdivision, and that each new subdivision presents an incremental burden on the existing Fire Department resources, a secure water source shall be provided for all subdivisions consisting of five lots or more, and an additional source shall be provided for each five additional lots. This water source shall consist of a dry hydrant connected to a storage tank with minimum capacity of 10,000 gallons (or such other capacity as may be designated by the Chief of the Town Fire Department), which tank shall be automatically maintained at full capacity by recharge from a well and pump system satisfactory, as shown to the Board in writing, to the Chief of the Town Fire Department. This water source shall be located within an easement on a lot within the subdivision, located at or near a roadway intersection. The easement shall be graded and provided with access meeting the Chief's requirements.
The entire area must be cleaned up so as to leave a neat and orderly appearance free from debris and other objectionable materials.