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the No. 200 sieve; no stone greater than two-third (2/3) loose lift thickness, or
six inches, whichever is smaller.

2. Select Backfill:

Select backfill shall be granular, well graded friable soil, free of rubbish, ice,
snow, tree stumps, roots, clay and organic matter, and other deleterious or
organic material; graded within the following limits:

Sieve Size Percent Finer by Weight
3” 100
No. 10 30 - 95
No. 40 10-70
No. 200 0-10

H. SPECIAL PIPE BEDDING MATERIAL

1. The special pipe bedding material shall consist of a filter cloth installed on the
trench bottom before backfilling with crushed stone as specified and as shown on
the contract drawings.

2. The filter cloth shall be composed of needle punch, stapled fibers thermally
bonded together to form a sheet.

3. The filter cloths shall possess the following minimum properties:

Grab strength: 1201bs ASTMD4632.
Elongation: 50% ASTM D 4632
Burst Strength: 240 psi ASTM D 3786
Puncture Strength: 65 Ibs. ASTM D 4833
Trapezoid Tear: 4 0 Ibs. ASTM D 4533
Equivalent opening size: No. 70 sieve ASTM D 4751
Permittivity (sec"') 1.8 ASTM D 4491
Flow Rate (gal/min/ft’) 135 ASTMD-4491

4. The filter cloth shall be Mirafi 140N by Muirafi, Inc. Charlotte, NC; Foss-65 by
Foss Manufacturing Co., Haverhill, MA; Supac 4NP, Phillips Fibers Corp.,
Greenville, SC or approved equal.

I, CRUSHED GRAVEL:

1. Crushed 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.

02300-4

2. The gradation shall meet the following requirements:

Sieve Designation Percentage Passing
3 in. 100

2 in. 95 — 100

1 in. 55-85

No. 4 27-52

No. 200 0-12

3. The approved source of bank-run gravel material shall be processed by
mechanical means. The equipment for producing crushed gravel shall be of
adequate size with sufficient adjustments to produce the desired materials. The
processed material shall be stockpiled in such a manner to minimize segregation
of particle sizes. All processed gravel shall come from approved stockpiles.

PART 3 — EXECUTION

3.01

A.

3.02

DISTURBANCE OF EXCAVATED AND FILLED AREAS
DURING CONSTRUCTION:

Contractor shall take the necessary steps to avoid disturbance of sub-grade during
excavation and filling operations, including restricting the use of certain types of
construction equipment and their movement over sensitive or unstable materials,
dewatering and other acceptable control measures.

All excavated or filled areas disturbed during construction, all loose or saturated soil,
and other areas that will not meet compaction requirements as specified herein shall
be removed and replaced with a minimum 12-inch layer of compacted crushed stone
wrapped all around in non-woven filter fabric. Costs of removal and replacement
shall be borne by the Contractor.

The Contractor shall place a minimum of 12-inch layer of special bedding materials
and crushed stone wrapped in filter fabric over the natural underlying soil to
stabilize areas which may become disturbed as a result of rain, surface water runoff
or groundwater seepage pressures, all at no additional cost to the Owner. The
Contractor also has the option of drying materials in-place and compacting to
specified densities

EXCAVATION: A.
GENERAL:

1. The Contractor shall perform all work of any nature and description required
to accomplish the work as shown on the Drawings and as specified.

2. Excavations, unless otherwise required by the Engineer, shall be carried only
to the depths and limits shown on the Drawings. If unauthorized excavation is
carried out below required sub-grade and/or beyond minimum lateral limits
shown on Drawings, it shall be backfilled with gravel borrow and compacted
at the Contractor's expense as specified below, except as otherwise indicated.
Excavations shall be kept in dry and good conditions at all times, and all voids
shall be filled to the satisfaction of the Engineer.

02300-5

In all excavation areas, the Contractor shall strip the surface topsoil layer and
underlying subsoil layer separate from underlying soils. In paved areas, the
Contractor shall first cut pavement as specified in paragraph 3.02 B.1 of this
specification, strip pavement and pavement sub-base separately from
underlying soils. All excavated materials shall be stockpiled separately from
each other within the limits of work.

The Contractor shall follow a construction procedure, which permits visual
identification of stable natural ground. Where groundwater is encountered, the
size of the open excavation shall be limited to that which can be handled by the
Contractor's chosen method of dewatering and which will allow visual
observation of the bottom and backfill in the dry.

The Contractor shall excavate unsuitable materials to stable natural ground
where encountered at proposed excavation sub-grade, as directed by the
Engineer. Unsuitable material includes topsoil, loam, peat, other organic
materials, snow, ice, and trash. Unless specified elsewhere or otherwise
directed by the Engineer, areas where unsuitable materials have been
excavated to stable ground shall be backfilled with compacted special bedding
materials or crushed stone wrapped all around in non-woven filter fabric.

TRENCHES:
1.

Prior to excavation, trenches in pavement shall have the traveled way surface
cut in a straight line by a concrete saw or equivalent method, to the full depth
of pavement. Excavation shall only be between these cuts. Excavation support
shall be provided as required to avoid undermining of pavement. Cutting
operations shall not be done by ripping equipment.

Trenches shall be excavated to such depths as will permit the pipe to be laid at
the elevations, slopes, and depths of cover indicated on the Drawings. Trench
widths shall be as shown on the Drawings or as specified.

Where pipe is to be laid in bedding material, the trench may be excavated by
machinery to, or just below, the designated sub-grade provided that the
material remaining in the bottom of the trench 1s not disturbed.

If pipe is to be laid in embankments or other recently filled areas, the fill
material shall first be placed to a height of at least 12-inches above the top of
the pipe before excavation.

Pipe trenches shall be made as narrow as practicable and shall not be widened
by scraping or loosening materials from the sides. Every effort shall be made
to keep the sides of the trenches firm and undisturbed until backfilling has
been completed.

If, in the opinion of the Engineer, the sub-grade, during trench excavation, has
been disturbed as a result of rain, surface water runoff or groundwater seepage
pressures, the Contractor shall remove such disturbed sub-grade to a minimum
of 12 inches and replace with crushed stone wrapped in filter fabric. Cost of
removal and replacement shall be borne by the Contractor.

C. BUILDING AND FOUNDATION EXCAVATION:

1.

Excavations shall not be wider than required to set, brace, and remove forms
for concrete, or perform other necessary work.

02300-6

2.

After the excavation has been made, and before forms are set for footings, mats,
slabs, or other structures, and before reinforcing is placed, all loose or
disturbed material shall be removed from the sub-grade. The bearing surface
shall then be compacted to meet the requirements of this specification.

If, in the opinion of the Engineer, the existing material at sub-grade elevation 1s
unsuitable for structural support, the Contractor shall excavate and dispose of
the unsuitable material to the required width and depth as directed by the
Engineer. If, in the opinion of the Engineer, filter fabric is required; the
Contractor shall place filter fabric, approved by the Engineer, as per
manufacturer's recommendations. Crushed stone shall then be placed in lifts
and compacted to required densities. Backfill shall be placed to the bottom of
the proposed excavation.

D. EXCAVATION NEAR EXISTING STRUCTURES:

1.

Attention is directed to the fact that there are pipes, manholes, drains, and
other utilities in certain locations. An attempt has been made to locate all
utilities on the drawings, but the completeness or accuracy of the given
information is not guaranteed.

As the excavation approaches pipes, conduits, or other underground structures,
digging by machinery shall be discontinued and excavation shall be done by
means of hand tools, as required. Such manual excavation, when incidental to
normal excavation, shall be included in the work to be done under items
involving normal excavation.

Where determination of the exact location of a pipe or other underground
structure 1s necessary for properly performing the work, the Contractor shall
excavate test pits to determine the locations.

3.03 BACKFILL PLACEMENT AND COMPACTION:

A. GENERAL:

1.

2.

Prior to backfilling, the Contractor shall compact the exposed natural sub-
grade to the densities as specified herein.

After approval of sub-grade by the Engineer, the Contractor shall backfill areas
to required contours and elevations with specified materials.

The Contractor shall place and compact materials to the specified density in
continuous horizontal layers. The degree of compaction shall be based on
maximum dry density as determined by ASTM Test D 1557, Method C. The
minimum degree of compaction for fill placed shall be as follows:

Percent of
Location Maximum Density
Below pipe centerline 95
Above pipe centerline 92
Below pavement (upper 3 ft.) 95
Embankments 95
Below pipe in embankments 95
Adjacent to structures 92
Below structures 95

02300-7

The Engineer reserves the right to test backfill for conformance to the
specifications and Contractor shall assist as required to obtain the information.
Compaction testing will be performed by the Engineer or by an inspection
laboratory designated by the Engineer, engaged and paid for by the Contractor.
If test results indicate work does not conform to specification requirements, the
Contractor shall remove or correct the defective Work by re-compacting where
appropriate or replacing as necessary and approved by the Engineer, to bring
the work into compliance, at no additional cost to the Owner. All backfilled
materials under structures and buildings shall be field tested for compliance
with the requirements of this specification.

Where horizontal layers meet a rising slope, the Contractor shall key each layer
by benching into the slope.

If the material removed from the excavation is suitable for backfill with the
exception that it contains stones larger than permitted, the Contractor has the
option to remove the oversized stones and use the material for backfill or to
provide replacement backfill at no additional cost to the Owner.

The Contractor shall remove loam and topsoil, loose vegetation, stumps, large
roots, etc., from areas upon which embankments will be built or areas where
material will be placed for grading. The sub-grade shall be shaped as indicated
on the Drawings and shall be prepared by forking, furrowing, or plowing so
that the first layer of the fill material placed on the sub-grade will be well
bonded to the sub-grade.

Where called for on the Drawings, Lightweight Fill shall be placed and
compacted as recommended by the manufacturer. The exact number of passes
shall be approved by the Engineer to insure stability of the layer. As soon as
the compaction of each layer has been completed, the next layer shall then be
placed. The Contractor shall take all necessary precautions during construction
activities in operations on or adjacent to the Lightweight Fill to insure that the
material is not over-compacted. Construction equipment, other than for
compaction, shall not operate on the exposed Lightweight Fill. The top surface
of the Lightweight Fill lying directly below the gravel course shall be chinked
by additional rolling of the Lightweight Fill to prevent infiltration of fines.

B. TRENCHES:

1.

Bedding as detailed and specified shall be furnished and installed beneath the
pipeline prior to placement of the pipeline. A minimum bedding thickness shall
be maintained between the pipe and undisturbed material, as shown on the
Drawings.

As soon as practicable after pipes have been laid, backfilling shall be started.
Unless otherwise indicated on the Drawings, select backfill shall be placed by
hand shovel in 6-inch thick lifts up to a minimum level of 12-inches above the
top of pipe. This area of backfill is considered the zone around the pipe and
shall be thoroughly compacted before the remainder of the trench 1s backfilled.
Compaction of each lift in the zone around the pipe shall be done by use of
power-driven tampers weighing at least 20 pounds or by vibratory compactors.
Care shall be taken that material close to the bank, as well as in all other
portions of the trench, is thoroughly compacted to densities required.

02300-8

3.04

4. Class B backfill shall be placed from the top of the select backfill to the

specified material at grade (loam, pavement sub-base, etc.). Fill compaction

shall meet the density requirements of this specification.

5. Water Jetting:

a. Water jetting may be used when the backfill material contains less than
10 percent passing the number 200 sieve, but shall be used only if
approved by the Engineer.

b. Contractor shall submit a detailed plan describing the procedures he
intends to use for water jetting to the Engineer for approval prior to any
water jetting taking place.

c. Compaction of backfill placed by water jetting shall conform to the
requirements of this specification.

6. If the materials above the trench bottom are unsuitable for backfill, the
Contractor shall furnish and place backfill materials meeting the requirements
for trench backfill, as shown on the drawings or specified herein.

7. Should the Engineer order crushed stone for utility supports or for other
purposes, the Contractor shall furnish and install the crushed stone as directed.

8. In shoulders of streets and the road, the top 12-inch layer of trench backfill
shall consist of crushed gravel for sub-base, satisfying the requirements of
NHDOT.

BACKFILLING ADJACENT TO STRUCTURES:

1. The Contractor shall not place backfill against or on structures until they have
attained sufficient strength to support the loads to which they will be
subjected. Excavated material approved by the Engineer may be used in
backfilling around structures. Backfill material shall be thoroughly compacted
to meet the requirements of this specification.

2. Contractor shall use extra care when compacting adjacent to pipes and drainage
structures. Backfill and compaction shall proceed along sides of drainage
structures so that the difference in top of fill level on any side of the structure
shall not exceed two feet (2') at any stage of construction.

3. | Where backfill 1s to be placed on only one side of a structural wall, only hand-
operated roller or plate compactors shall be used within a lateral distance of
five feet (5') of the wall for walls less than fifteen feet (15') high and within ten
feet (10') of the wall for walls more than fifteen feet (15') high.

DISPOSAL OF SURPLUS MATERIALS:

No excavated material shall be removed from the site of the work or disposed of by
the Contractor unless approved by the Engineer.

Surplus excavated materials, which are acceptable to the Engineer, shall be used to
backfill normal excavations in rock or to replace other materials unacceptable for
use as backfill. Upon written approval of the Engineer, surplus excavated materials
shall be neatly deposited and graded so as to make or widen fills, flatten side slopes,
or fill depressions; or shall be neatly deposited for other purposes as indicated by
the Owner, within its jurisdictional limits; all at no additional cost to the Owner.

02300-9

Surplus excavated clean material not needed as specified above shall be hauled away
and disposed of by the Contractor at no additional cost to the Owner, to the Nashua
Landfill. Arrangements must be made with the Owner prior to delivery. Disposal
of all rubble shall be in accordance with all applicable local, state and federal
regulations.

END OF SECTION

02300-10

SECTION 02324

ROCK EXCAVATION AND DISPOSAL

PART1-GENERAL

1.01

1.02

1.03

1.04

A.

B.

WORK INCLUDED:

The Contractor shall excavate rock, if encountered, to the lines and grades indicated on the
drawings or as directed, shall dispose of the excavated material, and shall furnish the
required material as specified in Section 02300 EARTHWORK for backfill in place of the
excavated rock.

RELATED WORK:

Section 02300, EARTHWORK

Section 02252, SUPPORT OF EXCAVATION
Section 03302, FIELD CONCRETE
DEFINITIONS:

The word "rock," wherever used as the name of the excavated material or material to be
excavated, shall mean only boulders and pieces of concrete or masonry exceeding one
cubic yard in volume, or solid ledge rock which, in the opinion of the Engineer, requires for its
removal, drilling and blasting, wedging, sledging, barring, or breaking up with a
power-operated tool. No soft or disintegrated rock which can be removed by normal earth
excavation methods, no loose, shaken, or previously blasted rock or broken stone in rock
fillings or elsewhere, and no rock exterior to the maximum limits of measurement allowed,
which may fall into the excavation, will be measured or allowed as "rock."

The word "earth," wherever used as the name of an excavated material, or material to be
excavated shall mean all kinds of material other than rock as above defined.

QUALITY ASSURANCE:

The Contractor shall conform to all municipal ordinances and state and federal laws
relating to the transportation, storage, handling, and use of explosives. In the event that any of
the above mentioned laws, ordinances, or regulations require a licensed blaster to
perform or supervise the work of blasting, said licensed blaster shall, at all times, have his
license on the work site and shall permit examination thereof by the Engineer or other
officials having jurisdiction.

The Contractor shall procure all permits required for blasting.

02324-1

1.05 SUBMITTALS:

A. At least two weeks before beginning blasting operations, the Contractor shall submit to the
Engineer for record the following data:

Name of Contractor or Subcontractor responsible for blasting and monitoring
operations and license number.

1.

Name, affiliation, and license number of the person or persons who will be directly

2.
responsible for designing each blast, supervising the loading of the shot, and firing it.

B. Copies of all permits required for blasting.

C. Results of pre-blast survey.
When blasting is in progress, daily reports on blasting operations and blast monitoring
results.

1.06 DELIVERY/STORAGE AND HANDLING:

Delivery, storage and handling of explosives shall conform to all federal, state and local

regulations and permits.

PART 2 - PRODUCTS - NOT APPLICABLE

PART 3 - EXECUTION

3.01 PREPARATION/PRE-BLAST SURVEY

If required, the pre-blast survey shall be conducted in accordance with state regulations

and/or local permit requirements.

3.02 EXCAVATION:

The Contractor shall excavate rock to the lines and grades indicated on the drawings or as
directed by the Engineer. The excavated rock shall be removed and disposed of by the
Contractor as specified for surplus excavated materials under Section 02300,

EARTHWORK.

A.

B. Work damaged by blasting shall be repaired or replaced at the Contractor's expense.

If rock 1s excavated beyond the limits of payment indicated on the drawings, specified, or
authorized in writing by the Engineer, the excess excavation, whether resulting from
over-breakage or other causes, shall be backfilled, by and at the expense of the Contractor,

as specified below:

C.

In pipe trenches, excess excavation shall be filled with the required material and
compacted in the same manner as specified for the material in the zone around the

pipe under Section 02300 EARTHWORK.

1.

02324-2

2. In excavations for structures, excess excavation in the rock beneath foundations shall be
filled with concrete which shall have a minimum 28-day compressive strength of 3000
psi. Other excess excavation shall be filled with Class B backfill compacted to a
minimum of 92 percent density (ASTM D1557 Method C) as specified under
Section 02300, EARTHWORK.

3. — If the rock below normal depth is shattered due to drilling or blasting operations of
the Contractor, and the Engineer considers such shattered rock to be unfit for
foundations, the shattered rock shall be removed and the excavation shall be
backfilled with concrete as required, except that in pipe trenches crushed stone may be
used for backfill, 1f approved. All such removal and backfilling shall be done by and at
the expense of the Contractor.

D. When directed by the Engineer, the Contractor shall remove all dirt and loose rock from
designated areas and shall clean the surface of the rock thoroughly to determine whether
seams or other defects exist.

E. When concrete 1s to be placed on rock, the rock shall be free of all vegetation, dirt, sand,
clay, boulders, scale, excesstvely cracked rock, loose fragments, water, ice, snow, and other
objectionable substances.

3.03 VIBRATION AND AIR BLAST MONITORING:

A. The Contractor shall measure air blast and vibration levels of blasting operations to assure
compliance with all applicable regulations and local permits.

B. — Records of each day's air blast and vibration measurements shall be submitted to the
Engineer in writing no later than the start of the next day's work. Records shall include, as a
minimum:

Identification of instrument
Name of observer
Name of interpreter
Distance and direction of recording station from the area of detonation

Date and exact time of reading

Type of ground at recording station

Peak particle velocity for all components as well as resultant for all frequencies of
vibrations

Duration of motion with a velocity in excess of one thousandth of an inch per second A

copy of the photographic record of seismograph readings Peak air blast level.

02324-3