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PART 3 —EXECUTION

3.01 INSTALLATION:

A. Work shall not be started until all materials and equipment necessary for their construction are
either on the site of the work or satisfactorily available for immediate use as required.

B. _ The sheeting shall be securely and satisfactorily braced to withstand all pressures to which it
may be subjected and be sufficiently tight to minimize lowering of the groundwater level
outside the excavation.

C. __No sheeting may be left so as to create a possible hazard to safety of the public or a
hindrance to traffic of any kind.

D. Ifboulders or very dense soils are encountered, making it impractical to drive a section to the
desired depth, the section shall be cut off.

E. The sheeting shall be left in place where indicated on the drawings or ordered by the
Engineer in writing. At all other locations, the sheeting may be left in place or salvaged at
the option of the Engineer. Steel sheeting permanently left in place shall be cut off at a depth
of not less than two feet below finish grade unless otherwise directed.

F. All cut-off will become the property of the Contractor and shall be removed by him from the
site.

G. Sole responsibility for the satisfactory construction and maintenance of the excavation
support system, complete in place, shall rest with the Contractor. Any work done,
including incidental construction, which is not acceptable for the intended purpose shall
be either repaired or removed and reconstructed by the Contractor at his expense.

H. The Contractor shall be solely responsible for repairing all damage associated with
installation, performance, and removal of the excavation support system.

END OF SECTION
2019 Sewer Replacement Project Support of Excavation

Nashua, NH 02252-2

SECTION 02300

EARTHWORK

PART 1 - GENERAL

1.01

1.02

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7

1.03

WORK INCLUDED:

The Contractor shall make excavations of normal depth in earth for trenches and structures,
shall backfill and compact such excavations to the extent necessary, shall furnish the
necessary material and construct embankments and fills, and shall make miscellaneous
earth excavations and do miscellaneous grading.

RELATED WORK:

Section 01110, CONTROL OF WORK AND MATERIALS

Section 02085, POLYVINYL CHLORIDE GRAVITY PIPE AND FITTINGS
Section 02252, SUPPORT OF EXCAVATION

Section 02370 - EROSION CONTROL

Section 02518, TRACER TAPE

Section 02745, ROAD RESTORATION

REFERENCES:
American Society for Testing and Materials (ASTM)

ASTM C131 Test Method for Resistance to Degradation of Small Size Coarse
Aggregate by Abrasion and Impact in the Los Angeles Machine.

ASTM C136 ~— Method for Sieve Analysis of Fine and Coarse Aggregates.
ASTM C330 _— Specification for Lightweight Aggregate for
Structural Concrete.

ASTM = D1556_ Test Method for Density of Soil in Place by the Sand Cone
Method.

ASTM _D1557 Test Methods for Moisture-density Relations of Soils and Soil
Aggregate Mixtures Using Ten-pound (10 Lb.) Hammer and
Eighteen-inch (18") Drop.

ASTM = D2922 Test Methods for Density of Soil and Soil-aggregate in Place by
Nuclear Methods (Shallow Depth).

2019 Sewer Replacement Project Earthwork
Nashua, NH 02300-1

1.04

1.05

1.06

1.07

SUBMITTALS: IN ACCORDANCE WITH REQUIREMENTS OF GENERAL
SPECIFICATIONS, SUBMIT THE FOLLOWING:

Material test results performed by a certified laboratory shall be submitted to the
Engineer for all materials proposed for use on the project. If required by the Engineer,
samples shall be submitted for independent testing.

PROTECTION OF EXISTING PROPERTY:

The work shall be executed in such manner as to prevent any damage to facilities at the site
and adjacent property and existing improvements, such as but not limited to streets, curbs,
paving, service utility lines, structures, monuments, bench marks, observation wells,
and other public or private property. Protect existing improvements from damage
caused by settlement, lateral movements, undermining, washout and other hazards
created by earthwork operations.

In case of any damage or injury caused in the performance of the work, the Contractor
shall, at its own expense, make good such damage or injury to the satisfaction of, and
without cost to, the Owner. Existing roads, sidewalks, and curbs damaged during the
project work shall be repaired or replaced to at least the condition that existed at the start
of operations. The Contractor shall replace, at his own cost, existing benchmarks,
observation wells, monuments, and other reference points which are disturbed or
destroyed.

Buried drainage structures and pipes, observation wells and piezometers, including those
which project less than eighteen inches (18") above grade, which are subject to damage
from construction equipment shall be clearly marked to indicate the hazard. Markers shall
indicate limits of danger areas, by means which will be clearly visible to operators of trucks
and other construction equipment, and shall be maintained at all times until completion
of project.

DRAINAGE:

The Contractor shall provide, at its own expense, adequate drainage facilities to complete

all work items in an acceptable manner. Drainage shall be done in a manner so that runoff
will not adversely affect construction procedures or cause excessive disturbance of
underlying natural ground or abutting properties.

FROST PROTECTION AND SNOW REMOVAL:

The Contractor shall, at its own expense, keep earthwork operations clear and free of
accumulations of snow as required to carry out the work.

The Contractor shall protect the sub-grade beneath new structures and pipes from frost
penetration when freezing temperatures are expected.

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Nashua, NH 02300-2

PART 2 - PRODUCTS

2.01 MATERIAL:

A.

C.

CRUSHED GRAVEL:
The Gravel Road Base will be NHDOT - Item 304.3 Crushed Gravel, or Item
304.4 Crushed Stone (Fine Gradation).

TRENCH BACKFILL MATERIALS:

Trench backfill shall be material excavated from the trench that is granular, well
graded friable soil; free of pavement, rubbish, ice, snow, tree stumps, roots, clay
and organic matter; with 30 percent or less passing the No. 200 sieve; no stone
greater than two-third (2/3) loose lift thickness, or six inches, whichever is
smaller.

SEWER AND DRAIN PIPE BEDDING MATERIAL

1. Sewer and drain pipe bedding material shall be Crushed Stone meeting the ASTM
C33/C33M stone size No. 67..

2. Sand Blanket material for sewer and drain pipe shall be graded sand free from
organic materials, graded such that 100 percent passes a %-inch sieve and a
maximum of 15 percent passes a #200 sieve.

PART 3 — EXECUTION

3.01

A.

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

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Nashua, NH 02300-3

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 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.

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.

2. 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.

3. 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 is not disturbed.

4. If pipe is to be laid in embankments or other recently filled areas, the fill

2019 Sewer Replacement Project Earthwork
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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 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 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:

L.

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 is necessary for properly performing the work, the Contractor shall
excavate test pits to determine the locations.

2019 Sewer Replacement Project Earthwork

Nashua, NH

02300-5

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.

2019 Sewer Replacement Project Earthwork

Nashua, NH

02300-6

B. TRENCHES:

1.

we

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 is 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
to meet the requirements of this specification.

2019 Sewer Replacement Project Earthwork
Nashua, NH 02300-7

2. Contractor shall use extra care when compacting adjacent to pipes and
drainage structures. Backfill and compaction shali 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

2019 Sewer Replacement Project Earthwork
Nashua, NH 02300-8

SECTION 02370
EROSION CONTROL
PART 1 - GENERAL

1.01 WORK INCLUDED:
A. Provide temporary erosion control for the entire duration of project in accordance with

plans, specifications.
B.
1.02 RELATED WORK:
A. Section 02300: EARTHWORK
B. Section 02745: ROAD RESTORATION
C. Section 02920: LOAMING AND SEEDING

1.03 SITE CONDITION:

A. All soil erosion and sediment control measures to be in accordance with standards and
specifications thereof in "Stormwater Management, and Erosion and Sediment Control
Handbook for Urban and Developing Areas in New Hampshire," April 1997, prepared
by Rockingham County Conservation District for NHDES in cooperation with USDA-
SCS.

B. The work area shall be graded, shaped, and otherwise drained in such a manner as to
minimize soil erosion, siltation of drainage channels, damage to existing vegetation,
and damage to property outside the limits of the work area. Silt fences, hay bales
and/or detention basins will be necessary to accomplish this end.

PART 2 —- PRODUCTS
2.01 MATERIALS:

A. SILTSACK®:

Sediment control devices at catch basins shall be SILTSACK® as manufactured by
Terrafix Geosynthetics, Inc., or approved equal.

B. Stabilized Construction Entrance:

2019 Sewer Replacement Project Erosion Control
Nashua, NH 02300-1