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3.02 EXCAVATION:

A. GENERAL:

1.

2.

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

Excavations, unless otherwise required by the Engineer, shall be carried only to
the depths and limits shown on the Drawings. If unauthorized excavation 1s
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.

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.

B. 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

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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.

2.

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

After the excavation has been made, and before forms are set for footings, mats,
slabs, or other structures, and before reinforcing 1s 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 is
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.

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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
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.

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B. TRENCHES:

1.

Qo

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 1s 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.

Trench 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.

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.

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.

Should the Engineer order crushed stone for utility supports or for other

purposes, the Contractor shall furnish and install the crushed stone as directed

by the Engineer.

In roadways, the specified base course gravels and pavement shall be placed as

specified.

A tracer tape shall be furnished and installed as specified Section 02518,

TRACER TAPE

C. 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
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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 is 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.

3.04 DISPOSAL OF SURPLUS MATERIALS:

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

B. — 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.

C. Surplus excavated clean material not needed as specified above shall be hauled away
and disposed of by the Contractor at the Nashua Landfill. Arrangements must be
made with the landfill prior to delivery. Disposal of all rubble shall be in accordance
with all applicable local, state and federal regulations.

END OF SECTION

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SECTION
02324

ROCK STRUCTURE
EXCAVATION AND DISPOSAL

PARTI-GENERAL

1.01 WORK INCLUDED:
The Contractor shall excavate rock, if encountered, to the lines and grades indicated in
the specifications 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.

1.02 RELATED WORK:
A. Section 02300, EARTHWORK
B. Section 02252, SUPPORT OF
EXCAVATION

1.03 DEFINITIONS:

A. 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."

B. 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.

1.04 QUALITY ASSURANCE:

A. 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.

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B. The Contractor shall procure all permits required for blasting.

1.05 SUBMITTALS:
A. At least two weeks before beginning blasting operations, the Contractor shall submit
to the

Engineer for record the following data:

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

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

D. 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:

A. 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.

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

B. Ifrock 1s excavated beyond the limits of payment as 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:

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.

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.

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, if 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 is to be placed on rock, the rock shall be free of all vegetation, dirt,
sand, clay, boulders, scale, excessively 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

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« 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.

3.04 BLASTING RECORDS:

The Contractor shall prepare and submit to the Engineer daily blast reports, including
logs of each blast. Reports shall be submitted to the Engineer no later than the start of
the next day's work. However, during each day of blasting, the Contractor shall review
and shall provide access for the Engineer to review the data from that day's blasting.
Reports after each blast shall include at least the following information for each blast:

Date, time, and location of
blast

Permit number and expiration
date

Amount and type of explosives used by weight and number of
cartridges

Total number of delays used and number of holes used for each
delay

On a diagram of the blast pattern, indicate total number and depth of holes,
maximum charge per delay, maximum charge per hole, and corresponding delay
number

An evaluation of the blast indicating areas of significant over-break, unusual
results, and any recommended adjustments for the next blast.

3.05 POST BLASTING INSPECTIONS:

The Contractor shall examine any properties, structures, and conditions where
complaints of damage have been received or damage claims have been filed. Advance
notice shall be given to all interested parties so that the parties may be present during
the final examination. Records of the final examination shall be signed and distributed
to the owner of the property, the head of the local fire department, and the Engineer.

END OF

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SECTION

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