Township of Byram, NJ Trench Excavation

The contractor shall not open more trench in advance of pipe laying than is necessary to expedite the work. One hundred feet shall be the maximum length of open trench permitted on any line under construction. Except where tunneling, jacking or boring is permitted by the Township or called for on the drawings, all trench excavation shall be open cut from the surface.

The alignment and grade or elevation of each pipeline shall be fixed and determined by means of offset stakes or other approved methods. Vertical and horizontal alignment of pipes and the maximum joint deflection used in connection therewith shall be in conformity with the requirements of the specifications covering the installation of the pipe laid in each case.

Trenches for force mains shall be carefully excavated so that the minimum cover over top of pipe will be 48 inches to existing street surface, or the future street surface when indicated, and so that the force main will slope continuously upward to point of discharge, to air release valves, if any, or to pump station. Greater cover at some locations along the line may be required due to street or ground profile and clearance of culverts, structures, utility lines, etc. Where force mains parallel gravity sewers, a separate trench may be dug, or a common trench may be dug providing a shelf of solid earth for the force main to rest on. When passing a manhole, the force main shall be bowed away from the manhole in a gentle arc not exceeding allowable deflection limits in accordance with manufacturer's recommendations or industry standards, whichever is more stringent.

Trenches shall be excavated to a width which will provide adequate working space and pipe clearance for proper installation, jointing and embedment. The minimum permissible trench widths and clearances between the installed pipe and either trench wall shall be as follows:

Pipe Size (inches)	Minimum Trench Width (inches)	Minimum Side Wall Clearance (inches)
6 or less	20	6
8	22	6
10	24	6
12	26	6
14	29	6
16	32	6
18	35	6

The stipulated minimum clearances are not minimum average clearances, but are minimum clear distances which will be permitted between any part of the pipe as laid and any part, projection or point of rock, shale, stone or boulder.

The maximum permissible trench widths below an elevation six inches above the top of the installed pipe shall not exceed the safe limit for the strength of pipe and class of bedding used. If so directed, the contractor shall provide evidence to the satisfaction of the Township Inspector that pipe strength is not exceeded relative to height of fill above the pipe, trench width and bedding class.

The maximum trench width for cast-iron pipe and ductile iron pipe shall not exceed the outside diameter of the pipe plus 24 inches. Where necessary to reduce the earth load on trench banks to prevent sliding and caving, the banks may be cut back on slopes which shall not extend lower than one foot above the top of the pipe, subject to the limitations above.

Unauthorized trench widths. Where, for any reason, the width of the lower portion of the trench as excavated at any point exceeds the maximum permitted in the foregoing tables, either pipe of adequate strength, special pipe embedment or Class A concrete arch encasement, as required by loading conditions and as determined by the Township, shall be furnished and installed by and at the expense of the contractor.

The use of mechanical equipment will not be permitted in locations where its operation would cause damage to buildings, culverts or other existing property, utilities or structures above or below ground; in all such locations, hand excavating tools and methods shall be used.

Mechanical equipment used for trench excavation shall be of a type, design and construction and shall be so operated that the rough trench excavation bottom elevation can be controlled, that uniform trench widths and vertical side walls are obtained at least from an elevation one foot above the top of the installed pipe to the bottom of the trench, and that the trench alignment is such that the pipe, when accurately laid to specified alignment, will be centered in the trench with adequate clearance between the pipe and side walls of the trench. Undercutting of the trench side wall to obtain clearance will not be permitted.

Cuts in concrete pavement and concrete base pavement shall be no larger than necessary to provide adequate working space for proper installation of pipe, pipe line appurtenances and paving replacement. Cutting shall be started with a groove at least 1 1/2 inches deep along each side of the trench and along the perimeter of cuts for structures.

Concrete pavement and concrete base pavement over trenches excavated for pipe lines shall be removed so that a shoulder no less than 12 inches in width at any point is maintained between the cut edge of the pavement and the top edge of the trench. Pavement cuts shall be made to and between straight or accurately marked curved lines which, unless otherwise required, shall be parallel to the center line of the trench.

Bituminous pavement over trenches shall be removed so that a shoulder not less than 18 inches in width at any point is left between the cut edge of the pavement surface and the top edge of the trench. A minimum of 12 inches in width of base material shall be removed from the edge of the trench to subgrade.

Pavement restoration or temporary restoration shall comply with the standard details of the contract drawings.

Except where otherwise required, pipe trenches shall be excavated below pipe subgrade elevations to provide for the installation of granular fill pipe foundation material.

(1)

Bell holes. Bell holes shall provide adequate clearance for the tools and methods used in installing the pipe. No part of any bell or coupling shall be in contact with the trench bottom, trench walls or the granular fill when the pipe is jointed.

§ 201-134 Dewatering and drainage.

The contractor shall keep all excavations free from water at all times. Drainage systems and pumping equipment shall be provided, maintained and operated as necessary. Drainage shall be controlled by a properly pumped system of well points, wells, sumps or other suitable means to protect excavations from an inflow or upflow of groundwater and to control groundwater to a sufficient depth below footing excavations and utilities to prevent any groundwater head from acting against the soil on which foundations and utilities are placed. Soil under foundations which has been disturbed by pressure or flow of groundwater shall be removed and foundations shall be lowered accordingly. Dewatering procedures will continue until the structures to be built are completed to the extent that no damage from hydrostatic pressure, flotation or other causes will result.

Flows from dewatering of trench or other excavation shall be discharged in an acceptable manner so as not to cause soil erosion or transport of silt. The contractor shall be responsible to provide a suitable temporary measure or siltation basin of such size and material as may be directed by the Engineer or Soil Conservation District representative consistent with practices set forth in the New Jersey Standards for Soil Erosion and Sediment Control.

Surface water shall be diverted or otherwise prevented from entering excavated areas or trenches to the greatest extent practicable without causing damage to lands adjacent to the project.

No pipe or reinforcing steel shall be installed in water nor shall water be allowed to come in contact with concrete for 12 hours after placing.

§ 201-135 Stabilization.

Subgrades for concrete structures shall be firm, dense and thoroughly compacted and consolidated; shall be free from mud and muck; and shall be sufficiently stable to remain firm and intact under the feet of the workmen.

Subgrades for concrete structures which are otherwise solid but which become mucky on top due to construction operations shall be reinforced with one or more layers of granular fill material or other crushed stone or gravel embedded therein. Not more than one-half-inch depth of mud or muck shall be allowed to remain on stabilized subgrade when the bedding material is placed thereon. The finished elevation of stabilized subgrades for concrete structures shall not be above the subgrade elevations shown on the plans.

Materials for stabilization shall be as specified hereinafter.

§ 201-136 Standard compaction and field density tests.

Wherever the terms "percent of maximum density" or "optimum moisture" are used, maximum density and optimum moisture shall be determined by the Standard Compaction Test described below.

Standard Compaction Test. The Standard Compaction Test shall be in accordance with AASHTO Design T99, except as modified below:

(1)

For samples containing no material retained on the No.4 sieve, use Method A or B. When the plasticity index of the soil is greater than 25 (heavy clays), the soil shall be placed in the mold in four layers, each compacted as outlined in the test method used.

(2)

For samples containing material retained on the No. 4 sieve, use Method D, preferably, or Method C. The amount retained on the three-fourths-inch sieve shall be weighed and discarded. To prepare the sample for the compaction test, the same amount of three-fourths-inch to No. 4 sieve material shall be substituted for the portion discarded.

Field Density Test. Field Density shall be obtained using the sand cone method ASSHTO Design T191, by the balloon method, nuclear densimeter or by use of any satisfactory materials or equipment suitable to the conditions prevailing in the material being tested. Maximum density as determined by the Standard Compaction Test to determine the percent compaction obtained.

§ 201-137 Pipe embedment and encasement.

Embedment materials both below and above the bottom of the pipe, the classes of embedment to be used, and the placement and compaction of embedment materials shall at a minimum conform to the following requirements.

Embedment materials. Granular bedding material shall be as specified hereinafter.

Placement and compaction.

(1)

All granular fill material beneath the pipe shall be spread and the surface graded to provide a uniform and continuous support beneath the pipe at all points between bell holes or pipe joints. It will be permissible to slightly disturb the finished subgrade surface by the withdrawal of pipe slings or other lifting tackle.

(2)

After each pipe has been graded, aligned and placed in final position on the bedding material and shoved home, sufficient pipe embedment material shall be deposited and compacted around each side of the pipe and back of the bell or end thereof to firmly hold and maintain the pipe in proper position and alignment during subsequent pipe jointing, embedment and backfilling operations.

(3)

Embedment material shall be deposited and compacted uniformly and simultaneously on each side of the pipe to prevent lateral displacement of the pipe and brought to the height above top of pipe as shown on the details.

(4)

Tamped pipe embedment material (that portion of the embedment above the granular fill) shall be selected earth or granular fill, free from sod, sticks, roots or rocks over three-fourths-inch size, and to be of proper moisture content for compaction.

(5)

Tamped pipe embedment material shall be compacted to 90% of maximum density, except where trench backfill is specified as 96% compacted backfill. In this case, the embedment material shall be compacted to 96% maximum density.

§ 201-138 Trench backfill.

General. All trench backfill above pipe embedment shall conform to one of the following specifications:

New Jersey Department of Transportation (NJDOT) rights-of-way. Work in, on or along rights-of-way belonging to the State of New Jersey shall be governed by the rules and regulations of the New Jersey Department of Transportation relating to the laying of pipe or construction of other structures on their right-of-way. The contractor shall be responsible for complying with said regulation and shall be fully responsible to the NJDOT for any work preformed upon these rights-of-way. All backfill within rights-of-way ditch lines shall be made with an approved granular material.

County roads and rights-of-way. All work in county roads and rights-of-way shall be governed by the rules and regulations of Sussex County.

Street and road rights-of-way. All backfill for pipe trenches between the ditch lines in street and road rights-of-way shall be made with an approved granular material. If the contractor elects to use excavated material for backfill, he shall mechanically tamp the backfill in layers not exceeding the depth that can be properly compacted by the equipment in use. The contractor shall demonstrate the compaction technique and provide compaction tests at his expense to determine the depth of layers to be placed.

Lawns and unimproved areas. All backfill for pipe trenches in lawns and unimproved areas may be placed by any method or combination of methods which will not impose excessive concentrated or unbalanced loads, shock, impact on or displacement of the installed pipe. Backfilling shall be completed in a manner to prevent trench settlement. In fields and unimproved areas, the trench shall receive reasonable compaction and may be mounded. The mounded area shall not impound water or otherwise damage the property through which the pipeline is constructed. The contractor shall maintain and clean up all work through private property, and he shall be responsible for any damage. The trenches shall be maintained for a period of one year after acceptance of the entire contract.

Special compacted backfill. When directed in writing by the Township, the following specifications shall prevail. Payment shall be made by the unit price bid for special compacted backfill as included in the bid schedule.

(1)

Ninety-percent compacted backfill. Backfill material shall be selected earth or granular fill material, free from sod, sticks and roots over 1/2 inches in diameter, and free from hard lumps, clods or rocks in such quantity or concentration as to interfere with the specified compaction. Material shall be of proper moisture content for specified compaction.

(a)

If specified density cannot be obtained with available earth, the contractor shall furnish and haul granular fill material or suitable earth at his expense. Unsuitable earth shall be disposed of and transported in conformance with local, county and state regulations.

(b)

Backfill shall be compacted to 90% of maximum density. The Township will call for density tests to be made whenever deemed necessary. The specified density will be the minimum allowed and the obtainment thereof will be entirely the contractor's responsibility.

(c)

Thickness of backfill layers will be determined by the coordination of test results with field performance and equipment used. The contractor shall maintain established procedures except where unusual conditions arise. If greater than twelve-inch-thick compacted layers are used, the contractor shall hand excavate to the test level as directed by the Township Inspector and then refill the test excavation with compacted backfill to the specified density.

(2)

Ninety-six percent compacted backfill. Specification is the same as in Subsection E(1) except that 96% of maximum density is required.

§ 201-139 Fill below concrete slabs.

After completion of the subgrade preparation work and all required filling, compacting and rough grading work to bring the subgrade to proper alignment and cross section at proper elevation, provide a layer of granular drainage fill, six inches thick, minimum, after compaction as a base course for all concrete slabs on grade or fill. Fill under walks and paved areas shall be a minimum of six inches. This shall include the entire area inside building and all concrete paved areas outside the building such as walks, approaches, etc. Compaction of material shall be to 96% of maximum density at optimum moisture content.

Compact bottom of all footing excavations in granular soils with vibratory compactor with minimum of three passes over each area just prior to placing of reinforcing steel.

§ 201-140 Backfill around structures.

Backfill around structures shall meet the same requirements as for the pipeline connected thereto. Methods used shall be such as not to damage the structure or cause the structure to float due to hydrostatic uplift.

§ 201-141 Granular fill material and placement.

Granular fill for stabilization, pipe bedding or pipe embedment shall be crushed stone meeting the allowable gradation envelope of NJDOT No. 57 Stone as follows:

1 1/2 inches	Square mesh sieve	100%	Passing
1 inch	Square mesh sieve	95 to 100%	Passing
1/2 inch	Square mesh sieve	25 to 60%	Passing
No. 4 Mesh	Square mesh sieve	0 to 10%	Passing
No. 8 Mesh	Square mesh sieve	0 to 5%	Passing

Place granular fill on a suitable prepared subgrade in lifts not exceeding six inches and bring up evenly on both sides of pipe. Do not dump over side of trench in any manner that will bring earth into the granular fill area or displace the pipe. Compact, vibrate or slice with a shovel, in such manner that granular fill will take its final compaction and provide uniform and solid bearing under the pipe and its final compaction and provide uniform and solid bearing under the pipe and its haunches.

Around structures and above the pipe embedment, granular fill shall be brought up evenly on all sides in lifts not exceeding 12 inches.

Minimum compaction requirement for granular fill is 95% of maximum density.

Where granular fills are to be covered with concrete after the fills have been installed, the top surface thereof shall be graded to the required subgrade and covered with six mil polyethylene film.

§ 201-142 Surplus excavation.

Excavated material in excess of that required for backfill, fill or other purposes, including any stored surplus, shall be disposed of properly. Conformance with local, county and state regulations relative to disposal and transport of materials shall be observed.

§ 201-143 Rough grading.

Rough grading shall be accomplished over all areas within the grading limit lines and over all areas which are disturbed by any work for the project. Rough grading shall consist of bringing grade to elevations as specified and thoroughly compacting by machine or by hand as necessary. Do grading to approved stakes.

Do no grading until sewers, water mains and other utilities are installed.

Later, if fill and/or backfill has settled, fill shallow places to bring them up to grade. Include areas where trenches were backfilled.

Rough grading of all areas within the project, including excavated and filled sections and adjacent transition areas, shall be reasonably smooth, compacted and free from irregular surface changes. The degree of finish shall be that ordinarily obtainable from either blade-grader or scraper operations, except as otherwise specified.

§ 201-144 Final grading.

Pavement and pavement base materials, excavated rock, junk and debris encountered in excavation work, and other similar waste material, shall be disposed of away from the site of the work.

Where uncompacted backfill is permitted or specified, excess earth from excavation shall be mounded directly over the pipe trench, in such a manner that the earth will settle into the trench as natural consolidation occurs. Openings for natural drainage shall be provided. The mounded earth shall be graded to a smooth, uniform surface. That portion of the earth displaced by the pipe shall be uniformly and smoothly graded adjacent to the trench.

For all types of backfill other than uncompacted, the contractor shall dispose of excess excavated material above the surface of the ground or subgrade of pavement, walks, etc.

Fine grade, suitable for seeding or sodding. Hand rake earth off grass in established lawn areas, unless directed to leave excess earth as outlined above.

Just prior to completion and acceptance of the project, the contractor shall final grade over all pipe trenches and around structures, filling any places that may have settled during the period between construction and the completion of the entire contract.

§ 201-145 Responsibility of contractor for backfill settlement.

The contractor shall be responsible financially and otherwise for all settlement of trench and other backfill which may occur from the time of original backfilling until the expiration of one year after the date of acceptance of the entire contract under which the backfilling work was performed, and for the refilling and repair of all backfill settlement and the repair or replacement or the original walks, surface structures, utilities, drainage facilities and sod which have been damaged as a result of backfill settlement or which have been removed or destroyed in connection with backfill replacement operations, and for all damage claims or court actions against the Township for any damage directly or indirectly caused by backfill settlement.

The contractor shall make all necessary backfill replacements and repairs, or replacements appurtenant thereto, within 30 days after notification by the Township. Upon the contractor's failure to do so, the Township may do, or have done, the necessary work and charge the cost to the contractor.