Town of Lewisboro, NY Improvement Construction Specifications

All trees and brush within the limits of the area to be graded must be cleared. On curves, an additional amount shall be cleared wherever necessary to maintain visibility along the inside pavement edge of at least 150 feet.

All dead trees or those in a hazardous condition within the right-of-way or adjacent to it and in danger of falling into the right-of-way shall be removed. Under certain conditions this may include a strip above the upper limits of cut slopes.

[Amended 12-12-1978]

The Planning Board may waive the clearing of certain trees upon request, or upon its own initiative may request that certain trees within the right-of-way be preserved.

All roots and stumps within the limits of areas to be graded shall be grubbed and excavated to a depth of two feet below the final finished grade except in fills greater than two feet where they shall be cut flush with the ground surface. Otherwise, where trees are cleared and grubbing is not required, the trunks shall be cut off not more than six inches above the original ground surface.

Walls, footings, etc., shall be removed to a depth of at least two feet below the proposed finished grades. Such areas shall be backfilled and graded over.

Stripping. The developer shall strip all topsoil from the bed of the proposed roadway and from all surfaces to be disturbed by cut or fill. Topsoil shall be kept separate from all other classes of excavated materials and shall be stockpiled on the site for finished grading. It shall not be removed from the property except in compliance with the Town ordinances.

Unsuitable material. All unstable material such as muck, humus, spongy material, soft clay, bogs and any other objectionable materials below the proposed subgrade shall be removed and the area filled with acceptable materials and well compacted.

Preparation of subgrade.

The subgrade shall be brought to the required grade by excavation or filling. All suitable and acceptable material from excavation shall be used for making embankments and backfilling as required. Tree trunks, limbs and other perishable materials shall not be incorporated in the fill, but shall be removed.

[Amended 12-12-1978]

All grading shall be done to conform to the approved construction plan and profiles and to provide a completed cross section as shown on the construction standards.

Side slopes shall have a graded slope of not more than one foot vertical for each two feet horizontal in cut or fill in earth, and not more than six feet vertical for one foot horizontal in rock.

Backfill for all drainage structures and culverts shall be as specified in § 195-31B.

[Amended 12-12-1978]

The subgrade shall be formed by repeated rolling, shaping, removal of unsuitable material and replacement with suitable materials, rerolling and reshaping until a uniform hard, stable surface properly crowned to shed water laterally is provided.

(6)

Embankments shall be formed of suitable and acceptable excavated materials. The fill shall be spread in layers not to exceed 12 inches in depth extending across the entire fill area. It shall be bladed or spread to an even surface, free from all clods and thoroughly compacted by rolling with approved rollers. Successive layers shall not be placed until the layer under construction is thoroughly compacted. Sections not accessible to the roller may be backfilled in eight inch layers and compacted with approved mechanical hand tampers.

(7)

Fill within 12 inches of finished grade shall be free of stone larger than six inches in greatest dimension.

(8)

All hollows and depressions which develop during the process of rolling and compacting shall be filled with acceptable materials, and the subgrade shall again be compacted.

(9)

Filling and compacting operations shall continue alternately until no depressions result and the subgrade conforms to the lines, grades and typical cross sections shown on the approved road plans.

(10)

If there is not sufficient excavated material of a suitable quality within the limits of work to complete embankments, grading and the backfilling to required lines and grades, the material may be brought in from outside sources subject to the quality being approved by the Town.

(11)

Any surplus suitable material shall be used for extending the shoulders to a greater uniform width or for flattening the embankment slopes or shall be deposited in spoil areas.

(12)

Excavations for head walls shall be made large enough to provide adequate clearance and depths for construction and accurate lines and grades.

(13)

Trenches for pipes shall be excavated to the required line and grade, shall have a firm finished bottom to grade and shall be of sufficient width to lay pipes, enable caulking and jointing to be done advantageously and to permit thorough tamping of backfill.

(14)

Selected materials only shall be used for backfill, free from large lumps, clods, stone or rock, and placed in layers not exceeding six inches in depth, each layer being thoroughly compacted.

(15)

Ledge rock in trenches shall be removed below grade and replaced with a compacted earth cushion of suitable materials at least eight inches in depth below the pipe.

Blasting. Explosives shall be stored and used in conformity with state laws and Town ordinances. Both state and Town permits must be obtained.

Slope grading. Prior to installation of bank gravel foundation, course slopes shall be laid back to proper grade, scarified, topsoiled and seeded. This shall be done in conjunction with the erosion control standards. No more than 500 feet of road shall be brought to subgrade without bank stabilization.

[Added 12-12-1978]

§ 195-30 Pavement.

General. All road pavements shall be composed of five inches of asphalt consisting of 3 1/2 inches of binder and 1 1/2 inches of top course. Thicknesses stated are after compaction.

[Amended 12-12-1978]

Conditions for laying of pavement. The laying of asphalt concrete and penetrated macadam pavement will be permitted between April 15 and November 15, when the air temperature is 50° F. and rising or warmer and the temperature of the surface on which the paving is to be laid is 45° F. or higher. Such paving at other times or conditions will require the written permission of the Town's Engineer.

Bank gravel foundation course. Foundation course for all roads shall be of crushed run-of-bank gravel placed on a properly prepared subgrade to the compacted thickness shown on the construction standards.

Acceptable material. Material acceptable for foundation courses shall consist of sound, hard, durable gravel, well-graded from coarse to fine. Particles shall have a maximum diameter equal to 2/3 of the thickness of the compacted layer of the foundation course under construction, but shall not exceed such size as will pass through a two-inch-square screen. Thirty percent to 65% by weight shall pass a one-fourth-inch-square mesh sieve, and not more than 10% by weight shall pass a No. 200 mesh sieve. The material passing a No. 40 mesh sieve shall have a maximum Plasticity Index of 5, when tested according to ASTM D424. When the material is subjected to four cycles of magnesium sulphate soundness test (ASTM C88), the weighted loss shall not exceed 20%. All material acceptable for this course shall contain suitable proportions of coarse and fine particles so that by the addition of proper amounts of water, a thoroughly stable, well-bound course will be produced whose surface will not weave or be displaced after compaction.

Spreading and compaction.

After the subgrade has been properly prepared, the gravel shall be spread evenly so that it will have, after rolling, the proper thickness. No segregation of large or fine particles will be allowed, but the gravel as spread shall be well graded, with no pockets of fine material.

The finished thickness of the foundation course shall consist of one four-inch layer of crushed gravel spread, rolled and filled, plus an additional four-inch layer of crushed gravel spread, rolled and filled.

(c)

After the gravel has been spread, it shall be thoroughly rolled with an approved roller weighing not less than 10 tons. All holes or depressions found in rolling shall be filled with gravel and the surface rerolled until it conforms to the lines and grades as shown on the construction standards and the approved construction plans for the particular subdivision. In all cases, the foundation course shall be true to grade and section, and so thoroughly compacted that it will not weave under a roller.

Asphalt concrete.

General requirements. Asphalt concrete pavement shall be constructed as shown on the construction standards. Asphalt concrete up to two inches in thickness shall consist of one top course meeting all requirements of Item 51, Asphalt Concrete, Type 1A, top course only, of the state specifications. Asphalt concrete over two inches in thickness shall consist of two equal thicknesses of binder and top courses meeting all requirements of Item 51, Asphalt Concrete, Type 1A, of the state specifications.

Priming or penetration of previous course.

Where asphalt concrete pavement is to be placed on a crushed bank-run gravel foundation, the foundation course shall be primed with a medium curing liquid asphalt, Grade MC-1, as per ASTM D598, heated to a temperature between 80° F. and 150° F. It shall be applied uniformly over the surface by means of pressure distributors at a rate of 0.2 gallon to 0.6 gallon per square yard, dependent on the gradation of the surface, to ensure a minimum penetration of one inch.

Where asphalt concrete pavement is to be placed on a penetrated macadam base, the macadam base shall be constructed as specified by the Town Engineer.

Composition of binder course. Composition of the bituminous plant mixture for the binder course shall conform to the following:

Screen Size (inches)	General Limits Percent Passing	Job Mix Percent Tolerance
1 1/2	100%	0
1	90% to 100%	+/-5
1/2	35% to 65%	+/-6
1/4	10% to 35%	+/-4
1/8	5% to 20%	+/-3*

Type of Mix	Percent of Mix	Job Mix Percent Tolerance
Hydrated lime	0.5 to 1.0	+/-0.2
Liquifier	0.4 to 1.0	+/-0.2
Asphalt cement**	4.0 to 5.5	+/-0.4

	NOTES:
	*	The No. 20 mesh screen and subsequent screens do not apply to the aggregates of the binder courses passing the one-eighth-inch screen.
	**	Asphalt cement shall be as specified in Subsection D(5), Composition of asphalt cement.

Composition of top course. Composition of the bituminous plant mixtures for the top course shall conform to the following:

Screen Size	Type 1A, Hot Process General Limits Percent Passing	Job Mix Percent Tolerance
1 inch	100%	0
1/2 inch	95% to 100%	+/-5
1/4 inch	65% to 85%	+/-5
1/8 inch	32% to 65%	+/-6
No. 20 mesh screen	15% to 39%	+/-7
No. 40 mesh screen	7% to 25%	+/-6
No. 80 mesh screen	3% to 12%	+/-3
No. 200 mesh screen	2% to 6%	+/-2

Type of Mix	Percent of Mix	Temperature	Job Mix Percent Tolerance
Asphalt cement	5.8 to 7.0	—	+/-0.4
Penetration of asphalt cement	—	85° F. to 100° F.	—
Placing temperature	—	225° F. to 300° F.	—

Composition of asphalt cement. The asphalt cement used in the binder and top courses shall be a paving grade asphalt meeting the requirements hereafter specified, and shall be introduced into the pugmill at a temperature compatible with the aggregates between the limits of 225° F. and 350° F. Asphalt cement shall conform to the following:

	Type	Specification
	Grade	85 to 100
	Water	0.0
	Homogeneous	Yes
	Pen. @ 77° F. 100 g. 5 sec.	85 to 100
	Pen. Ratio (39.2° F./77° F. x 100)	30.0+
	% Loss @ 325° max.	See Note A below
	% Pen. of Res. min.	60.0
	% Sol. in CCI4 min.	See Note B below
	Flash Point, °F. min.	347
	Duct. @ 77° F. min.	60

	Note A: 1.0% limit for Pet. Asphalts; 3.0% for Fluxed Nat. Asphalt.
	Note B: 99.5+ Pet. Asphalts; 95.0+ Bermudez; 81.0+ Cuban; 66.0+ Trinidad.
	Method of tests: AASHTO

(6)

Approval of job mix formulas. The subdivider shall submit to the Town's engineer for approval the actual job mix formulas. Once approved, the composition of the mix shall lie within the job mix tolerance set forth in Subsection D(3), Composition of binder course, or Subsection D(4), Composition of top course, of these specifications. The aggregate tolerances shall be based on the total weight of the aggregate, and the asphalt cement tolerances shall be based on the total weight of the mix. In no case shall the job mix tolerances fall outside the general limits for a particular mix. Before approving the paving, the Planning Board shall require the subdivider to submit a certificate from a responsible representative of the plant supplying the paving mixture, stating the compositions, daily quantities and delivery dates of the mix furnished to the subdivider.

(7)

Asphalt concrete; method for rolling.

After placing, and while still hot and workable, the course shall be rolled with a ten- to twelve-ton, three-wheel, power-driven roller, an eight- to ten-ton tandem roller or a roller producing a compression with the rear wheels of not less than 250 pounds per inch of tread. Rollers shall have steel wheels and shall travel parallel to the center line of the pavement, beginning at each edge and working toward the center, overlapping on successive trips by 1/2 the rear wheel of the roller. All rollers shall be of a type acceptable to the Town's engineer. Rollers shall be operated at a speed satisfactory to the Town's engineer, but not to exceed three miles per hour. Rolling shall proceed continuously. Wheels of the roller and of the paver shall be kept clean at all times. They may be kept moist with water or a mixture of water with not more than 10% lubricating oil, as directed. Dirty water, petroleum solvents or grease shall not be allowed to drop from the roller or paver onto the pavement.

If depressions remain after rolling, additional pavement mixture shall be added at such points and firmly rolled into place. After rolling has been completed, the surface of the course shall have the required crown, density and thickness and shall be of the grade established for the surface of the finished pavement. Any unsatisfactory areas shall be removed and replaced with suitable material.

§ 195-31 Other improvements.

Gutters.

[Amended 12-12-1978]

In general, gutters shall not exceed 300 feet in length to a point of discharge.

Where required, paved gutters shall be constructed on grades of 5% or more with asphaltic concrete or Portland cement concrete, laid on a six-inch compacted bank gravel base. The Portland cement concrete shall have a minimum thickness of three inches and the asphaltic concrete shall be a minimum of three inches thick after compaction.

Gutters shall be paved integral with road binder and top course.

All runoffs shall be paved with asphaltic concrete, a minimum thickness of three inches after compaction, and shall extend the full length of the slope.

Culverts and storm drains.

Pipes of sufficient size and capacity shall be located where necessary to provide adequate drainage without ponding.

Pipes.

[Amended 12-12-1978]

Pipes for all culverts shall be fully asphalt-coated helically corrugated steel pipe. Corrugated steel pipe shall conform to the requirements of AASHTO designation M-36. Pipe shall be helically corrugated with all pipe seams continuously welded. On each pipe end there shall be two rolled annular corrugations to facilitate band connection. Pipe and connecting bands shall be plain galvanized in accordance with AASHTO designation M-36. Connecting bands shall be 0.064 inch thick minimum, and shall be the hugger band type or the annular corrugated band type. Connecting bands must engage each pipe end with at least one matching annular corrugation. Dimple bands, flat bands, helical bands, etc., are not acceptable. Pipe shall be of the following minimum gauges:

	Pipe Diameter (inches)	Gauge
	15 to 24	16
	30	14
	36 to 48	12
	Over 48	10

Minimum pipe diameter shall be 15 inches. All culverts shall have a minimum cover of 18 inches. Culvert pipes shall extend to the toe of the embankment. All culverts shall be laid on a firm earth foundation which shall have been carefully shaped to line and grade.

Materials used in bedding and backfill shall be select materials from the on-site excavation. Backfill material shall be placed on both sides of the culvert or structure at the same time in equal approximately horizontal layers not exceeding eight inches in thickness before compaction and thoroughly compacted with an approved mechanical tamper of the whacker type to a subgrade level and shaped to receive other materials specified. The equipment used for compaction must be in good working order and subject to the approval of the Engineer. For compaction equipment in good working order, the Engineer may consider the manufacturer's recommendations or the results of actual field tests and allow an increase in thickness of uncompacted backfill, not exceeding 12 inches, based on the nature and moisture of the material to be compacted and the number of passes to be made with the compactor. A minimum dry density of 95% of the maximum density, which is the maximum dry weight in pounds per cubic foot as determined by the AASHTO Designation T-99, Method C, will be required. The contractor shall exercise special care in placing and compacting material immediately adjacent to pipe to avoid damage to a culvert or structure, or its alignment, regardless of cause, shall be replaced. Any material backfilled and/or compacted which does not comply with these specifications shall be removed and replaced.

[Amended 12-12-1978]

All excess mortar and debris shall be removed from the inside of the pipe, and the pipe shall be left in a clean, satisfactory working condition.

Storm drains discharging into streams or ponds shall maintain the invert at least one foot above normal high water mark. Velocity dissipation structures shall be provided at all culvert discharges.

[Amended 12-12-1978]

Headwalls.

At the inlet and discharge ends of culverts in embankments and the terminus of stormwater drains, a headwall shall be constructed to protect against erosion, unless catch basins or other drainage structures are required according to the design.

Headwalls shall be built of rubble stone masonry or first class concrete, with a top width of 18 inches and the rear face battered 1:4 as shown on the construction standards. The minimum length shall be six feet. The top elevation shall equal the ground surface and the bottom elevation shall be a minimum of 30 inches below the pipe invert.

Concrete headwalls shall be constructed of one-to-two-to-four concrete as shown on the construction standards.

Rubble stone masonry headwalls shall be built of clean stone, free from structural defects, laid in full cement mortar beds of one part Portland cement and three parts mortar sand. Vertical joints shall be flushed with mortar. Selected stone, roughly squared and pitched to line, shall be used for the copings and ends of walls.

The stone shall be laid on its natural bed to form substantial masonry, presenting a neat and finished appearance. Spalls and pinners shall not be allowed to show on the face of the wall and shall be used only where necessary. All stones shall be laid to break joints six inches or more and to thoroughly bond the work.

Catch basins.

At the inlet end of pipe drains or culverts in cut sections, a catch basin shall be constructed having minimum interior dimensions of two feet wide by three feet long. They shall be constructed on a base eight inches in thickness of one-to-two-to-four concrete at such an elevation that the floor of the basin is 18 inches below the elevation of the lowest outlet pipe.

Side walls shall have a minimum thickness of eight inches and shall be built of one-to-two-to-four concrete as specified for base, brick in mortar or concrete block in mortar.

Brick or concrete block shall be laid in mortar consisting of one part Portland cement and two parts mortar sand by a competent mason in a workmanlike manner, and both interior and exterior walls shall be plastered with the same mortar at least 1/4 inch thick.