EARTHWORK

EARTHWORK

PART 1 - GENERAL

1.1      THE REQUIREMENT

A.         The Work of this Section includes all earthwork required for construction of the Work.
Such earthwork shall include, but not be limited to, the loosening, removing, loading, transporting, depositing, grading and compacting in its final location of all materials wet and dry, as required for the purposes of completing the work specified in the Contract Documents, which shall include, but not be limited to, the furnishing, placing, and removing of sheeting, shoring and bracing necessary to safely support the sides of all excavation;  supporting  structures  above  and  below  ground;  all  pumping,  ditching, draining, dewatering, and other required measures for the removal or exclusion of water from the excavation; filling and compacting soil to elevations shown on the Contract Documents; all backfilling around structures and pipe and all backfilling of trenches and pits; the disposal of excess and unsuitable excavated materials; borrow of materials to make up deficiencies for fills; and all other incidental earthwork, all in accordance with the requirements of the Contract Documents.

B. The elevations shown on the drawings as existing are taken from the best available data and are intended to give reasonably accurate information.  The Contractor is responsible for determining exact quantities of excavation and fill required.

C. Pits and fills used for the erection of the Contractor's construction facilities shall be filled or removed upon the completion of the work and leveled to meet the existing contours of the adjacent ground surface.

D. After all structures have been completed, the ground surface shall be brought to the finished grade elevations and relative compaction indicated on the Contract Documents.

E. All finished ground surfaces shall be bladed and dressed to present a surface not varying over 0.10 foot at local humps or depressions and to the satisfaction of the Resident Project Representative.  Local depressions, which can contain water shall be no more than 0.05-foot deep.

F. Contaminated Soil:   The Contractor shall notify the Resident Project Representative if any soil suspected of being contaminated is encountered.  Contaminated soil contains chemical  or  biological  substances  which  are  hazardous  to  the  health  of  individuals working near the soil as defined under Sections 101(14) and 101(33) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), or volatile organic compounds listed in Rule 1166 of the South Coast Air Quality Management District.   Contamination is most likely to be found near underground fuel storage tanks and industrial waste disposal sites.

Upon notification by the Contractor, the Owner will immediately test the atmosphere near the soil for flammability, oxygen deficiency and hydrogen sulfide, and take soil samples as appropriate to determine the nature and extent of contamination.   The Owner will notify the County of Riverside - Health Services Agency, the California Regional Water Quality  Control  Board,  the  South  Coast  Air  Quality  Management  District  and  other required regulatory agencies having jurisdiction and obtain permits as necessary.

1.2      REFERENCE SPECIFICATIONS, CODES, AND STANDARDS

A.         Comply  with  the  applicable  reference  specifications  as  specified  in  the  General
Conditions.

B.         Comply with the current provisions of the following codes and standards:

1.         Commercial Standards

ASTM 136        Test Method for Sieve Analysis of Fine and Coarse Aggregates

ASTM 422        Test Method for Particle-Size Analysis of Soils

ASTM 1556      Test  Method  for  Density  of  Soil  in  Place  by  the  Sand-Cone
Method

ASTM 1557      Test Methods for Moisture-Density Relations of Soils and Soil- Aggregate  Mixtures  Using  10-lb  (4.54-kg)  Rammer  and  18-in (457-mm) Drop

ASTM 1633      Test Method for Compressive Strength of Molded Soil-Cement
Cylinders

ASTM 2166      Test Method for Unconfined Compressive Strength of Soils

ASTM 2419      Test  Method  for  Sand  Equivalent  Value  of  Soils  and  Fine
Aggregate

ASTM 2435      Test Method for One Dimensional Consolidation Properties of
Soils

ASTM 2487      Classification of Soils for Engineering Purposes

ASTM 2901      Test Method for Cement Content of Freshly-Mixed Soil-Cement

ASTM 2922      Test Methods for Density of Soil and Soil-Aggregate in Place by
Nuclear Methods (Shallow Depth)

ASTM 3017      Test Methods for Moisture Content of Soil and Rock in Place by
Nuclear Methods (Shallow Depth)

UBC No. 29-2  Test Method for Expansion Index of Soils

2.         Standard Specifications

SSPWC           Sections 203-1, 203-2, 203-3 - Bituminous Materials

SSPWC           Section 211 - Soil and Aggregate Tests

SSPWC           Section 300 - Earthwork

SSPWC           Section 306-1- Open Trench Operations

3.         California Labor Code.

4.         When  referenced  Standards  and  Standard  Specifications  conflict  with  these
Specifications, these Specifications shall govern.

1.3      SUBMITTALS

A.         Submittals, including samples  of  materials, shall be in accordance with the General
Conditions.

B. The Contractor’s attention is directed to Section 6705 of the California Labor Code and SSPWC Section 306-1.1.   The Contractor, prior to beginning any trench or structure excavation 5 feet deep or over shall submit to the Resident Project Representative the Contractor’s detailed plan showing design of all shoring, bracing, sloping of the sides of excavation,  and  other  provisions  for  worker  protection  against  the  hazard  of  caving ground during the excavation of such trenches or structure excavation.  The plans shall be prepared by a qualified civil or structural engineer licensed in the State of California and employed by an independent design firm.   The submittal(s) shall include a site location  map  referencing  existing  features;  detailed  plans;  elevations,  and  various sections indicating all excavation slopes, shoring components and connections and showing all structures and utilities potentially influenced by the performance of shoring, trenching or structure excavation along with supporting calculations; notes including sequence of construction, materials, and other clarification as required by the California Labor Code, SSPWC, and the Contract Documents.   The Contractor shall be solely responsible for the adequacy of the excavation and surface water drainage control plan or for furnishing all equipment, labor, and materials necessary for performing the various parts of the Work.

C. If dewatering is required, the Contractor shall submit for the drawings and data showing his proposed design and plan for dewatering of all work areas, which shall include the planned method of dewatering, excavation and shoring, the location and capacity of such facilities as dewatering wells, well points, pumps, sumps, collection and discharge lines, the standby units proposed, and protective fills and ditches required for control of groundwater and surface water.   The plan for dewatering shall be submitted to the Resident Project Representative 21 days prior to the start of construction. The Contractor shall furnish such other information as may be required for the complete understanding of the dewatering and excavation plan by the Resident Project Representative.

D. The  Contractor  shall  be  solely  responsible  for  the  adequacy  of  the  dewatering  and excavation plan or for furnishing all equipment, labor, and materials necessary for performing the various parts of the work.   If, during the progress of the work, it is determined by the Engineer that the dewatering system and excavation plan are inadequate or the Contractor’s plan of construction inoperative, the Contractor shall, at his expense, furnish, install and operate such additional dewatering equipment as may be necessary to perform the work in a manner satisfactory to the Resident Project Representative.

1.4      DEWATERING

A. Based on the information in the two geotechnical reports performed for the Owner (Phase I Geotechnical Investigation by Leighton Consulting dated May 20, 2005, and Geotechnical Engineering Report Three Barrel Inverted Siphon Crossing Beneath CVWD Stormwater   Channel   by   Earth   Systems   Southwest   dated   June   11,   2004),   the groundwater elevations were encountered at between Elevation 440 and 420 (or 30 to 50
feet below the pond dike).  The borings in the both reports were made in March.  Based on these groundwater elevations, the Owner has assumed that the existing wastewater ponds are not leaking and may not impact the groundwater elevation.   The Contractor shall assess the groundwater situation; determine dewatering needs based on his expertise, assessment, and experience; and include the cost of dewatering as Additive Bid Item A in the Bid Schedule.  If the dewatering is in fact required, the Contractor shall be responsible for providing the necessary dewatering within the price listed in Additive Bid Item A.   If the dewatering is not required, the Owner will deduct the amount for Additive  Bid  Item  A  from  the  contract  amount.    If  the  dewatering  is  required,  the Contractor shall provide the dewatering as specified below.

B. The Contractor shall design, provide and maintain, at all times during construction, ample means and devices with which to promptly remove and properly dispose of all water from any source, including water migrating through existing adjacent pond berms and through the bedding of existing pipelines, entering the excavations or other parts of the work. Dewatering shall be accomplished by methods that will ensure a dry excavation and preserve the final lines and grades of the bottoms of excavations.  For work within the boundaries of the treatment plant, dewatering methods may include deep wells, well points, or other methods suitable for the accomplishment of the work.   The proposed method shall be submitted to the Resident Project Representative for information purpose only.

C. The dewatering shall be accomplished in a manner that will prevent loss of fines from the foundation, will maintain stability of all excavated slopes and bottoms of excavations, and will permit construction operations to be performed in the dry.  Dewatering of excavations shall be performed to the extent required to permit placement of compacted fill materials in the dry and to prevent sloughing of the excavation side slopes.

D. No  concrete  or  masonry  footings,  foundations,  manhole  bases,  or  floors  shall  be constructed in water, nor shall water be allowed to rise over them until the concrete or mortar has set at least 24 hours.  Water shall not be allowed to rise unequally against walls until concrete has attained its 28-day strength.  Water shall not be allowed to rise above pipe subgrade during pipelaying operations.

E. Dewatering equipment shall not cause noise nuisance.  Noise levels shall, at a minimum, comply with the requirements of local jurisdictions or permitting agencies

F. The Contractor shall construct and maintain all permanent and temporary slopes, dikes, levees, drainage ditches, and sumps necessary for removal of water from work areas.

G. Any damage or settlement to the foundation or other work or any existing structures caused by temporary or permanent failure or operation of the dewatering system shall be repaired to the satisfaction of the Resident Project Representative at the Contractor’s expense.  The Contractor should consider the use of recharge systems or other methods of protection of existing facilities.   The Contractor shall monitor settlement, and groundwater levels around existing structures during dewatering.  Records of settlement and groundwater levels shall be kept and evaluated on a daily basis.   The Contractor shall notify the Resident Project Representative immediately if excessive settlement or a significant drop in groundwater is recorded.

H. Standby pumping equipment shall be on the job-site.  A minimum of one standby unit (a minimum of one for each ten in the event well points are used) shall be available for immediate installation should any well unit fail.  The design and installation of well points or deep wells shall be suitable for the accomplishment of the work.  Drawings indicating
the   proposed   dewatering   system   shall   be   submitted   to   the   Resident   Project
Representative for information.

I. If foundation soils are disturbed or loosened by the upward seepage of water or an uncontrolled flow of water, the affected areas shall be excavated and replaced with pipe bedding material at no cost to the Owner.

J. The Contractor shall dispose of the water from the work in a suitable manner without damage to adjacent property.  Conveyance of the water shall not interfere with traffic flow or the operation of the treatment facilities. No water shall be drained into work built or under construction without prior consent of the Resident Project Representative.  Upon written approval of the Owner, water may be disposed of in the treatment plant ponds, effluent system, or trunk sewer at a point designated by the Resident Project Representative.  Water shall be desanded before disposal in any sewer.  Disposal point and maximum flow rate for dewatering waste is subject to the Engineer’s review.  The Resident Project Representative shall have the right to limit the maximum flow rate per disposal point and may direct the Contractor to provide additional disposal points as required at no additional cost.

K. The system used for desanding the water shall be a baffled structure and shall provide not less than 5 minutes detention time and have a "flow-through" velocity not exceeding
0.2 feet per second at the anticipated peak flow.  The desanding box shall be cleaned as required to maintain the detention time and flow-through limitations specified above.  The method of desanding and point of disposal of water shall be subject to the Owner’s approval.  Water shall be disposed of in such a manner as not to be a menace to the public health and shall be done in accordance with Environmental Protection Agency, Army Corps of Engineers and State Water Quality Control Board requirements.

L. Contractor shall dewater all water migrating from the bedding of existing sewers at no additional cost to the Owner.

M. Upon completion of the dewatering and control of water operation, all temporary works and dewatering facilities shall be removed in a manner satisfactory to the Resident Project Representative.

1.5      SHORING OF EXCAVATIONS

A. The Contractor shall be fully and solely responsible for providing and constructing shoring and bracing to prevent slides or cave-ins and to protect all existing improvements in the vicinity from damage as required.

1. Shoring and sheeting shall also be installed during excavation as necessary to prevent disturbing material that is under an adjacent structure or pipe.

2. Whenever the Resident Project Representative considers any Owner facility in jeopardy due to excavation, the Contractor shall take the measures necessary, subject to approval of the Owner, to protect the facility in question.   All costs associated with these protective measures shall be borne by the Contractor. Backfill of any "unauthorized excavation" shall be performed as directed by the Resident Project Representative.   Damage to existing structures due to "unauthorized excavation" shall be immediately repaired or replaced to the satisfaction of the Resident Project Representative at the Contractor’s expense.

3. All piling required for shoring shall be installed by drilling.   Driven piles of any types will not be allowed.

4. The Contractor shall not begin excavation operations until the shoring drawings have been delivered to the Engineer.  Receipt of the Contractor’s shoring plans shall not be constructed to invalidate other provisions of these Specifications or relieve the Contractor of his sole responsibilities inherent in the pursuance of the work.  The Contractor shall, at its cost and for all its shoring work, obtain permits from all regulatory agencies as required.

5. The Contractor shall furnish all labor, equipment, and materials to construct, install,  and  remove  the  entire  shoring  system  including  removal  of  lagging, soldier beams, and bracing and detensioning of tiebacks.  Full compensation for the shoring and its removal shall be considered as included in the Contract Price and no additional compensation will be allowed.

6. Design of shoring shall be in accordance with the applicable requirements of the Safety Orders of the Division of Industrial Safety, State of California.   The Contractor shall be responsible for providing more extensive shoring or bracing systems   than   those   required   by   the   Construction   Safety   Orders   when necessitated by conditions indicated on the drawings, specified, or otherwise required by the work.

7. The shoring and bracing shall be designed in accordance with the data provided in the Geotechnical Investigation Report and shall consider all surcharge loads imposed.

8. Where  the  shoring  support  system  is  within  10  feet  of  a  street,  it  shall  be designed to withstand a minimum surcharge load equivalent to 2 feet in height of earth added to the active earth pressure in the upper 10 feet of shoring.  Shoring support systems adjacent to other structures shall be designed to withstand all loads applied to the shoring system from adjacent structures.

9. Where  shoring  will  support  adjacent  structures  or  facilities  and  excessive deflection can lead to structure settlement, braced or tieback shoring shall be utilized.  Braced or tieback shoring supporting adjacent nearby facilities shall be designed  and  constructed  to  limit  the  maximum  horizontal  deflection  of  the shoring to 1 inch or less.  Deflection of the shoring system shall be monitored on a weekly basis by a licensed surveyor employed by the Contractor.  Monitoring of the shoring shall be performed in the presence of the Resident Project Representative, with a written report to be submitted to the Resident Project Representative within 24 hours.

10. Any  delay  and/or  expense  incurred  due  to  excess  shoring  deflection  or inadequate shoring performance shall be at the Contractor’s expense.

1.6      SAFETY MEASURES

A. Safe conditions shall be maintained at the jobsite meeting all provisions of the California OSHA and all other applicable safety codes.   Barricades and lighting meeting the requirements of all agencies having jurisdiction shall be placed at each end of all excavations and at such places as may be necessary along excavations to warn all pedestrians and vehicular traffic of such excavations.  Lights shall also be placed along excavations from sunset each day to sunrise of the next day until such excavation is
entirely backfilled, compacted, and paved.   All excavations within the treatment plant fenced property shall be barricaded and lighted in such a way as to prevent persons from falling  or  walking  into  any  excavation.    All  excavations  outside  the  treatment  plant confines shall be fenced with a minimum 7-foot high chain link fence during all non- working hours.  This fence shall be constructed to prevent any person from entering the excavation.  Signs stating "Danger, Deep Hole" shall be clearly displayed on all sides of the excavation.

B. Safe and suitable ladders that project 2 feet above the top of the trench shall be provided for all trenches greater than 4 feet in depth.  A minimum of one ladder shall be provided for each 50 feet of open trench.

1.7      QUALITY ASSURANCE

A. General:   All soils testing will be done by a testing laboratory of the Resident Project Representative’s choice at Owner’s expense except as specified in Subsection C and F below.

B. The Owner will pay for the initial cost of all compaction tests. If any compaction fails to meet the relative compaction tests set forth, the Contractor shall pay for subsequent compaction tests by deducting their costs from the Contract amount.

C. The Contractor shall make all necessary excavations for compaction tests as directed by the Resident Project Representative, and all work in connection with compaction testing by the Contractor shall be included in the various contract bid prices, and no additional allowance will be made therefore.  Safe access shall be provided to conduct the test.

D. Where soil material is required to be compacted to a percentage of maximum dry density, the maximum dry density at optimum moisture content will be determined in accordance with the latest version of ASTM D 1557.  In-place field density tests will be performed in accordance with ASTM D 1556, (sand cone) and/or ASTM D 2922 and ASTM D 3017 (nuclear gauge).  The type, number and location of field density tests will be determined by the Resident Project Representative.   One sand-cone test (ASTM D 1556) will be taken for every four nuclear tests (ASTM D 2922 and 3017).

E. All imported fill material shall be sampled at the Contractor’s expense and shall be subject to approval by the Engineer.

F. Where  imported  fill  material  is  required  to  possess  certain  gradation,  strength,  and settlement properties, the grain size distribution of soils will be determined using ASTM D
422, the gradation of concrete aggregate and base materials will be determined using ASTM C 136, the sand equivalent of soils will be determined using ASTM D 2419, the consolidation  of  soils  will  be  determined  using  ASTM  D  2435,  the  unconfined
compressive strength of soils will be determined using ASTM D 2166, and the expansion
index of soils will be determined using UBC No. 29-2.

G. Testing of soils shall also comply with any permit conditions included as part of this contract.
PART 2 - PRODUCTS

2.1      SUITABLE FILL AND BACKFILL MATERIAL REQUIREMENTS

A. General:  Fill, backfill, and embankment materials shall be suitable selected or processed clean, fine earth, rock, or sand, and free from grass, roots, brush, or other vegetation; contamination; or deleterious material.

Suitable materials may be obtained from onsite excavations, may be processed onsite materials, or may be imported provided these materials meet all the requirements in the Contract Documents.  If imported materials are required to meet the requirements of this Section or to meet the quantity requirements of the project, the Contractor shall provide the imported fill materials and the required reports of test results at no additional expense to the Owner.

B. Select Material:   Select material shall be free from organic matter or debris. All of the material shall pass through a 1-1/2-inch screen. Not more than 10 percent by weight shall pass the 200-mesh sieve and the material shall have sufficient gradation to compact to 95 percent relative compaction. Use of select material shall be subject to the Engineer’s approval.

C.         Unclassified Fill:   Unclassified fill shall consist of all fill unless separately designated.
Unclassified fill shall conform to the requirements of SSPWC Section 300-4 and the requirements stated in the recommendations of the Geotechnical Report.

D. Granular Soil:  Wherever the Term “granular soil” is used in the Contract Documents, it shall be defined as a soil having a minimum sand equivalent of 30 as determined in accordance   with   the   latest   revision   of   the   State   of   California,   Department   of Transportation, Test Method No. CA 217 and not more than 20 percent of it by weight will pass through a 200-mesh sieve.

E. Imported Sand:  Wherever the term “imported sand” is used in the Contract Documents, it shall be defined as sand having a minimum sand equivalent of 70 as determined by the latest revision of the State of California, Department of Transportation, Test Method No. CA 217.

F.         The following types of suitable granular materials are designated and defined as follows:

1. Crushed Aggregate Base (CAB) shall conform to the requirements of SSPWC Section 200-2.2.

2.         Crushed  Miscellaneous  Base  (CMB)  shall  conform  to  the  requirements  of
SSPWC Section 200-2.4.

3.         Crushed Rock:  Crushed rock shall be the product of crushing rock or gravel.
Fifty percent of the particles retained on a 3/8-inch sieve shall have their entire surface area composed of faces resulting from fracture due to mechanical crushing. Not over 5 percent shall be particles that show no faces resulting from crushing. Less than 20 percent of the particles that pass the 3/8-inch sieve and are retained on the No. 7 sieve shall be waterworn particles. Gravel shall not be added to crushed rock.
Where crushed rock is specified on the Contract Documents, it shall conform to the following gradation:



Sieve Sizes 3/4-inch Maximum
Crushed Rock% Passing  
2 inches -  
1 1/2- inches -  
1 inch 100  
3/4 inch 90-100  
1/2 inch 30-60  
3/8 inch 0-20  
No. 4 0-5  
No. 8 -

4. Gravel:     Gravel  shall  be  defined  as  particles  that  show  no  evidence  of mechanical crushing, are fully waterworn and are rounded. For pipe bedding where gravel is specified, crushed rock may be substituted or added. Where gravel is specified on the Contract Documents, the material shall have the following gradations:




Sieve Sizes 1-inch
Maximum
Gravel % Passing 3/8-inch
Maximum
Gravel % Passing  
2 inches - -  
1 1/2- inches 100 -  
1 inch 90-100 -  
3/4 inch 60-80 100  
1/2 inch - -  
3/8 inch 0-15 90-100  
No. 4 0-5 0-15  
No. 8 - 0-5

5. Drainrock shall be crushed rock or gravel, durable and free from slaking or decomposition under the action of alternate wetting or drying.  The material shall be uniformly graded and shall meet the following gradation requirements:


Sieve Size Percentage Passing  
1-inch 100  
3/4-inch 90 - 100  
3/8-inch 40 - 100  
No. 4 25 - 40  
No. 8 18 - 33  
No. 30 5 - 15  
No. 50 0 - 7  
No. 200 0 - 3

The drainrock shall have a sand equivalent value not less than 75.   The finish-graded surface of the drainrock immediately beneath hydraulic structures shall be stabilized to provide a firm, smooth surface upon which to construct reinforced concrete floor slabs.

G. Structure Backfill material shall conform to the requirements of SSPWC Section 300-3.5.1 and the requirements stated in the recommendations of the Geotechnical Report.
H. Pervious Backfill material shall conform to the requirements of SSPWC Section 300-3.5.2 and the requirements in the recommendations stated in the recommendations of the Geotechnical Report.

I. Pipe  Bedding  Material:    Unless  otherwise  indicated,  pipe-bedding  material  shall  be crushed rock, aggregate fill, granular soil, imported sand, or 3/8-inch maximum gravel as specified herein.

1. Type A Bedding material shall conform to the requirements for 3/4-inch Crushed Rock, 1-inch Crushed Rock, No. 3 Concrete Aggregate, No. 4 Concrete Aggregate, or Portland Cement Concrete Sand in SSPWC Section 200-1 for pipes larger than 24 inches in diameter.  Type A Bedding material shall conform to the requirements for Type B Bedding material or the requirements for Portland Cement Concrete Sand in SSPWC Section 200-1 for pipes 24 inches or smaller in diameter.

2.         Type B Bedding material shall conform to the requirements for 1-inch Crushed
Rock or No. 4 Concrete Aggregate in SSPWC Section 200-1.

3. Bedding material for concrete pipe shall conform to the requirements for ¾-inch or ½-inch crushed rock in SSPWC Section 200-1.

4. Pipe zone materials for ductile iron pipe with polyethylene wrap shall be granular soil, imported sand, or 3/8-inch maximum gravel in conformance with the requirements of SSPWC Section 200-1.

J. Sand-Cement Slurry material shall conform to the requirements of SSPWC Section 201-1 for Trench Backfill Slurry.

K. Soil Cement material shall conform to the requirements of SSPWC Section 301-3.1. L. Topsoil material shall conform to the requirements of SSPWC Section 212-1.1.
M. Provide Geotextile (Mirafi 140NC Non-woven, or equal) and Geogrid (Tensar BX 1300 Bi- axial or equal) as shown on the drawings.

2.2      USE OF FILL, BACKFILL, AND EMBANKMENT MATERIAL TYPES

A. The Contractor shall use the types of materials as designated herein for all required fill, backfill, and embankment construction hereunder.

B.         Fill and backfill types shall be used in accordance with the following provisions:

1. Pipe zone backfill, as defined in Paragraph 3.14 "Pipe and Utility Trench Backfill" herein, shall consist of the following materials for each pipe material listed below.

a. Mortar coated pipe, concrete pipe, and uncoated ductile iron pipe shall be provided Type A Bedding, Type B Bedding, or Concrete Pipe Bedding materials as defined in Subsection 2.1.J.2.

b. Coal tar enamel coated pipe, polyethylene encased pipe, tape wrapped pipe, and other non-mortar coated pipe shall be backfilled with Portland cement concrete sand conforming to SSPWC Section 200-1 or Concrete Pipe Bedding material as defined in Subsection 2.1.J.2.
c. Plastic  pipe  and  vitrified  clay  pipe  shall  be  backfilled  with  3/4-inch Crushed Rock conforming to SSPWC Section 200-1 or Concrete Pipe Bedding material as defined in Subsection 2.1.J.2.

2. Trench  zone  backfill  for  pipelines  as  defined  in  Paragraph  3.14  shall  be Unclassified  Fill  material  as  defined  in  Subsection  2.1.c,  unless  conditions require the use of a designated material as indicated in the Contract Documents.

3.         Final backfill material for pipelines under paved areas, as defined in Paragraph
3.14 shall be Crushed Aggregate Base (CAB) or Crushed Miscellaneous Base
(CMB) material as defined in 2.1.F.1 and 2.1.F.2.

4. Trench backfill and final backfill for pipelines under structures shall be the same material as used in the pipe zone, except where concrete encasement is required by the Contract Documents.

5. Aggregate base materials under pavements shall be Crushed Aggregate Base (CAB) or Crushed Miscellaneous Base (CMB) material constructed to the thicknesses shown or specified.

6. Backfill around or behind structures shall consist of Structure Backfill as defined in Subsection 2.1.H, unless indicated otherwise in the Contract Documents.

7. Fill materials beneath structures shall be as follows unless otherwise indicated on the drawings:

a. Fill beneath hydraulic structures or other water retaining structures with underdrain systems shall be drainrock material, as defined in Subsection
2.1.F.5, constructed to the limits and thicknesses shown or specified.

b. Fill  beneath  structures  without  underdrain  systems  shall  be  CAB  as defined in Subsection 2.1.F.

c. Fill beneath structures where groundwater must be removed to allow placement of concrete shall be crushed rock as defined in Subsection
2.1.F.

8. Backfill used to replace pipeline trench over-excavation shall consist of Type B Bedding material as defined in Subsection 2.1 I. 2.

9. The top 6 inches of fill on reservoir roofs, embankment fills around hydraulic structures, and all other embankment fills shall consist of Topsoil as defined in Subsection 2.1.L.

PART 3 - EXECUTION

3.1      CLEARING, GRUBBING AND STRIPPING

A.         Clearing, grubbing and stripping shall be performed in accordance with Section 02110.

3.2      GRADING AND STOCKPILING

A. The Contractor shall control grading in a manner to prevent water from running into excavations.   Obstruction of surface drainage shall be avoided and means shall be provided whereby storm water flow is not interrupted in existing gutters, and other surface drains, or temporary drains.   Material for backfill or for protecting excavation in public roads from surface drainage shall be neatly placed and kept shaped so as to cause the least possible interference with public travel.   Free access must be provided to all fire hydrants, watergates, meters, and private drives. Stockpiling of excavated material is not allowed in the street right-of-way.

B. Finished grading at any point shall not vary more than 0.10 foot above or below the grade established by the Contract Documents.

3.3      STRUCTURE, ROADWAY, AND EMBANKMENT EXCAVATION

A. General:  Except when specifically provided to the contrary, excavation shall include the removal of all materials of whatever nature encountered, including all obstructions of any nature that would interfere with the proper execution and completion of the work.  The removal of said materials shall conform to the lines and grades shown or ordered. Unless otherwise provided, the entire construction site shall be stripped of all vegetation, debris, and all deleterious materials, and such materials shall be removed from the site prior to performing any excavation or placing any fill.   The Contractor shall furnish, place, and maintain all supports and shoring that may be required for the sides of the excavations, and all pumping, ditching, or other measures for the removal or exclusion of water, including  taking  care  of  storm  water,  groundwater  (dewatering  if  required),  and wastewater reaching the site of the work from any source so as to prevent damage to the work or adjoining property.  Excavations shall be sloped or otherwise supported in a safe manner in accordance with applicable State of California safety requirements and the requirements of OSHA Safety and Health Standards for Construction (29CFR1926), and the Contract Documents.

Structure excavation shall conform to the dimensions and elevations indicated on the Contract  Documents  for  each  structure  including  trenching  for  adjacent  piping.    In locations where soil of suitable bearing value is encountered at a different elevation from that indicated on the Contract Documents, the Resident Project Representative may direct  in  writing  that  the  excavation  be  carried  to  elevations  above  or  below  those indicated on the Contract Documents. Excavation shall extend at least 24 inches from walls and footings to allow for placing and removal of forms, installation of services, and inspection.  Undercutting  will  not  be  permitted.  Where  a  structure  would  be  located partially on fill and partially on undisturbed native material, the entire area shall be over- excavated to a depth of 6 inches below the elevations indicated and recompacted to 95 percent  maximum  density.    Existing  ground  that  is  not  satisfactory  shall  be  over- excavated as specified in Section D below. Scarification shall continue until soils are broken down and free of large clay lumps or clods and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction.

Safe and suitable ladders that project 2 feet above the top of the trench shall be provided for all trenches greater than 4 feet in depth.  A minimum of one ladder shall be provided for each 50 feet of open trench.

B. Excavation Beneath Structures and Embankments:  Except where otherwise specified for a particular structure or ordered by the Resident Project Representative, excavation shall be carried to the grade of the bottom of the footing or slab.  Where shown or ordered, areas beneath structures or fills shall be over-excavated.  The subgrade areas beneath embankments shall be excavated to remove not less than the top 8 inches of native material and where such subgrade is sloped, the native material shall be benched.  When such over-excavation is shown, both over-excavation and subsequent backfill to the required grade shall be performed by the Contractor.  When such over-excavation is not shown on the drawings and not specified but is ordered by the Resident Project Representative, such over-excavation and any resulting backfill will be paid for under a separate bid item if such bid item has been established prior to commencing the work; otherwise payment will be made in accordance with a negotiated price.  After the required excavation  or  over-excavation  has  been  completed,  the  exposed  surface  shall  be scarified to a depth of 8 inches, brought to optimum moisture content, and rolled with heavy compaction equipment to obtain the required relative compaction.

C. Excavation  in  Poor  Soil:    If  excessively  wet,  soft,  spongy,  unstable,  or  otherwise unsuitable   material,   as   determined   by   the   Resident   Project   Representative,   is encountered at the bottom of the excavation or the surface upon which the pipe bedding material is to be placed including the vertical sides of a specified pipe trench, the unsuitable material shall be removed to a depth as required by the Resident Project Representative,  disposed  of,  and  replaced  with  approved  fill  or  bedding  material. Removal and replacement of material so ordered shall be paid for by the Owner as "Extra Work" unless provided for in the Schedule of Prices.   The Contractor shall maintain adequate dewatering procedures to ensure that an otherwise stable foundation will not be rendered unfit due to accumulation or movement of water in the excavation.   If the necessity for such additional excavation and material has been occasioned by an act or failure to act on the part of the Contractor, the Contractor shall bear the full expense of the additional excavation and backfill to the required depth.

D. Overexcavation:   In addition to removals and over-excavations recommended in the referenced geotechnical report(s) and the drawings, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be over-excavated to competent ground as directed by the Resident Project Representative. All undocumented fill soils under proposed structure footprints shall be excavated. Where excavation is carried below the limits shown on the Contract Documents, adjustments shall be made as determined by the Resident Project Representative to meet requirements incurred by the deeper excavation beneath pipe or structure. Overdepth excavation in such locations shall be rectified by backfilling with approved fill or bedding material or other means specified.   Overexcavation not required by the Contract Documents or directed by the Resident Project Representative shall be rectified at the expense of the Contractor.

E. Benching: Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units) or where indicated (>20 percent grade) the ground shall be stepped or benched as depicted on the Keying and Benching figure at the end of this appendix. The lowest bench or key shall be a minimum of 15 feet (4.5 m) wide and at least 2 feet (0.6 m) deep, into competent material.  Other benches shall be excavated a minimum height of 4 feet (1.2 m) into competent material. Fill placed on ground sloping flatter than 5: 1 (horizontal  to vertical units),  (less  than  20  percent grade) shall also be benched or otherwise overexcavated to provide a flat subgrade for the fill.

F. Excavation Beneath Paved Areas:  Excavation under areas to be paved shall extend to the bottom of the aggregate base, if such base is called for; otherwise it shall extend to the paving thickness.   After the required excavation has been completed, the exposed surface shall be scarified to a depth of at least 12 inches, brought to optimum moisture content, and rolled with heavy compaction equipment to obtain 95 percent of maximum dry density.

G.        Excavation Subgrade and Below Subgrade

1. Excavate  and  shape  subgrade  to  line,  grade,  and  cross-section  shown  on drawings.  Following receipt of written acceptance for the subgrade by the Owner and local building official, compact the subgrade with approved equipment until the top 6-inches is compacted to 95 percent of maximum dry density at optimum moisture content as determined by ASTM D 1557.   Remove all soft, loose, or otherwise unsuitable material and replace with suitable sandy material.   The finished subgrade shall be firm, hard and unyielding.   The subgrade shall be considered to extend over the full width of the base course.  Compaction shall extend 18 inches beyond the edge of paving, curb, or form.

2. Where  the  Resident  Project  Representative  deems  subgrade  material  to  be unsatisfactory, excavation below subgrade will be required to such depths as necessary to remove the unsatisfactory material.  Excavation below grade shall be of the same classification as that above it provided it is removed in the same operation as the normal excavation.  Special equipment or hand excavation may be required because of the presence of shallow utilities or other unforeseen conditions.

H. Notification of Resident Project Representative:  The Contractor shall notify the Resident Project Representative at least 2 working days in advance of completion of any structure excavation and shall allow the Engineer a review period of at least two days before the exposed foundation is scarified and compacted or is covered with backfill or with any construction materials.

3.4      PIPELINE AND UTILITY TRENCH EXCAVATION

A. General:  Any water evident in the excavation shall be pumped out or otherwise removed per Subsection 1.4 as necessary to keep the bottom of the excavation free and clear of water during the progress of the work.   Typical pipe trench details are shown on the drawings.

B. Limit  of  Open  Trench:    Except  by  express  written  permission  of  the  Engineer,  the maximum amount of open trench permitted in any one location shall be 500 feet, or the length necessary to accommodate the amount of pipe installed in a single day, whichever is  greater.    All  trenches  shall  be  fully  backfilled  and  paved  with  the  first  course  of pavement at the end of each day or, in lieu thereof, shall be covered by heavy steel plates adequately braced and capable of supporting vehicular traffic in those locations where it is impractical to backfill at the end of each day.   The above requirements for backfilling or use of steel plate will be waived in cases where the trench is located further than 100 feet from any traveled roadway or occupied structure.  In such cases, however, barricades and warning lights meeting OSHA requirements shall be provided and maintained. The maximum working length allowed without the first course of pavement is
1,000 feet.

C. Trench Bottom:  Except when pipe bedding is required, the bottom of the trench shall be excavated uniformly to the grade of the bottom of the pipe.  The trench bottom shall be given a final trim, using a string line for establishing grade, such that each pipe section when first laid will be continually in contact with the ground along the extreme bottom of the pipe.   Rounding out the trench to form a cradle for the pipe will not be allowed. Trench bottom raked by toothed excavators is not acceptable.

D. Trench  Over-Excavation:    Where  the  drawings  indicate  that  trenches  shall  be  over- excavated, they shall be excavated to the depth shown, and then backfilled to the grade of the bottom of the pipe.

E. Excavation  in  Poor  Soil:    If  excessively  wet,  soft,  spongy,  unstable,  or  otherwise unsuitable   material,   as   determined   by   the   Resident   Project   Representative,   is encountered at the bottom of the excavation or the surface upon which the pipe bedding material is to be placed including the vertical sides of a specified pipe trench, the unsuitable material shall be removed to a depth as required by the Resident Project Representative,  disposed  of,  and  replaced  with  approved  fill  or  bedding  material. Removal and replacement of material so ordered shall be paid for by the Owner as "Extra Work" unless provided in the schedule of prices.  The Contractor shall maintain adequate dewatering procedures to ensure that an otherwise stable foundation will not be rendered unfit due to accumulation or movement of water in the excavation.  If the necessity for such additional excavation and material has been occasioned by an act or failure to act on the part of the Contractor, the Contractor shall bear the full expense of the additional excavation and backfill to the required depth.

F. Where pipelines are to be installed in embankment or structure fills, the fill shall be constructed to a level at least one foot above the top of the pipe before the trench is excavated.

G. Obtain  Engineer’s  approval  before  beginning  excavation.     Complete  clearing  and grubbing prior to the start of trenching.  Do not permit excavated materials to cover brush or trees prior to disposal.

3.5      OVER-EXCAVATION NOT ORDERED, SPECIFIED, OR SHOWN

A. Any over-excavation by the Contractor carried below the grade not ordered, specified, or shown, shall be backfilled to the required grade with the specified material and compaction.  Such work shall be performed by the Contractor at his own expense.

3.6      EXCAVATION IN LAWN AREAS

A. Where  excavation  occurs  in  lawn  areas,  the  sod  shall  be  carefully  removed  and stockpiled to preserve it for replacement.  Excavated material may be placed on the lawn; provided, that a drop cloth or other suitable method is employed to protect the lawn from damage. The lawn shall not remain covered for more than 72 hours.  Immediately after completion of backfilling, compaction and testing of the pipeline, the sod shall be replaced in a manner so as to restore the lawn as near as possible to its original condition and to the satisfaction of the Resident Project Representative.  Contractor shall provide new sod if stockpiled sod has remained so for more than 72 hours within the scope of the contract. The top 3” of backfill shall remain uncompacted to promote growth.

3.7      EXCAVATION IN VICINITY OF TREES

A. Except where trees are shown to be removed, trees shall be protected in place from injury during construction operations.  No tree roots over 2 inches in diameter shall be cut without  express  permission  of the  Resident  Project  Representative.    Trees  shall  be supported and irrigated during excavation by means previously reviewed by the Engineer. The Contractor shall replace all trees that die that are shown on the Contract Drawings as being protected in place.

3.8      ROCK EXCAVATION

A. Rock excavation shall include removal and disposal of the following: (1) all boulders measuring 1/3 of a cubic yard or more in volume; (2) all rock material in ledges, bedding deposits, and unstratified masses which cannot be removed without systematic drilling and blasting; (3) concrete or masonry structures which have been abandoned; and (4) conglomerate   deposits   which   are   so   firmly   cemented   that   they   possess   the characteristics of solid rock and which cannot be removed without systematic drilling and blasting.

Where solid rock is encountered, it shall be removed below grade and the excavation backfilled  with  approved  pipe-bedding  material  to  provide  a  compacted  foundation cushion with a minimum thickness of 3 inches under the pipe bell.  Removal of rock and additional pipe bedding material over and above bedding required in the Contract Documents shall be paid for by the Owner as "Extra Work" unless provided for in the Schedule of Prices.

Cobbles  or  boulders  encountered  at  the  trench  bottom  or  pipe  subgrade  shall  be removed a minimum of 12-inches beneath the pipe and replaced with approved pipe bedding material.  Bedding material shall be compacted to 95 percent relative density per the Contract Documents to provide uniform support and a firm foundation.

B. Said rock excavation shall be performed by the Contractor; provided, that should the quantity of rock excavation be affected by any change in the scope of the work, an appropriate adjustment of the Contract Price will be made under a separate bid item if such bid item has been established; otherwise payment will be made in accordance with a negotiated price.

C. Explosives and Blasting:  Blasting will not be permitted, except by express permission of governing agencies on a case-by-case basis.  The use of explosives will be subject to the approval and regulations of all agencies having jurisdiction.  If blasting is utilized at the site of the Work, the Contractor shall take all precautions and provide all protective measures necessary to prevent damage to property and structures or injury to person. Prior to blasting, the Contractor shall secure all permits required by law for blasting operations and shall provide any additional hazard insurance required by the Owner.  The Contractor shall have fully qualified and experienced blasting personnel and foreman in charge of all blasting operations.

D. The Contractor will be held responsible for all and shall make good any damage caused by blasting or resulting from its possession or use of explosives on the Work.

E. All operations involving the handling, storage, and use of explosives shall be conducted in accordance with the requirements of the OSHA Standards for Construction, and in accordance with all local laws and regulations.

3.9      DISPOSAL OF EXCESS EXCAVATED MATERIAL

A. The Contractor shall remove and dispose of all excess excavated material at a site selected by the Contractor and reviewed by the Engineer.  All incurred expenses shall be borne by the Contractor.

B. Unsuitable material shall be defined as material containing excessive amounts of organic matter, peat, blue clay, trash or debris; or as designated by the Resident Project Representative; or debris produced by clearing, grubbing, and demolition of existing structures, pavement, or pipe; or soil classified by test method ASTM D2486 as groups OL, CH, MH, OH or PT; or not meeting the grading or classification specified for the work.

C. All unsuitable and surplus material outside of the confines of the treatment plants shall be disposed of in a legal manner by the Contractor and all costs associated with disposal shall be borne by the Contractor.  No unsuitable or surplus material shall be dumped on private property unless written permission is furnished by the owner of the property and unless a grading permit is issued from the local jurisdiction.

D. Unsuitable and surplus material within the confines of the treatment plants shall be disposed of by the Contractor as specified above.

E.         Excess unsuitable and surplus materials shall be kept separated from materials of other
Contractors working in the same area.

3.10    PROTECTION OF SUBGRADE

A.         After preparing the subgrade as specified, all traffic on the subgrade shall be avoided.
Should it be necessary to haul over the prepared subgrade, the Contractor shall drag and roll the traveled way as frequently as may be necessary to remove ruts, cuts, and breaks in the surface.   All cuts, ruts, and breaks in the surface of the subgrade that are not
removed by the above operations shall be raked and hand tamped.  All equipment used
for transporting materials over the prepared subgrade shall be equipped with pneumatic tires.

B. Continued use of sections of prepared subgrade for hauling, so as to cut up or deform it from the  true cross-section,  will  not  be  permitted.   The Contractor shall protect the prepared subgrade from all traffic.

C. The  Contractor  will  be  required  to  plank  the  subgrade  before  hauling  materials  or equipment over it.

D. The subgrade shall be maintained in the finished condition until the first succeeding course or steel or concrete is placed.

E. The Resident Project Representative has the right to test the reworked subgrade and approve or disapprove the subgrade depending on its condition.

3.11    BACKFILL – GENERAL

A. Fill Quality:  Material to be used as fill shall be essentially free of organic matter and other deleterious substances. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall not be used for backfill.

B. Oversize:    Oversize  material  defined  as  rock,  or  other  irreducible  material  with  a maximum dimension greater than 6 inches (15 cm), shall not be buried or placed in fill unless location, materials and placement methods are specifically accepted by the Geotechnical Engineer. Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 feet (3 m) measured vertically from finish grade, or within 2 feet (0.61 m) of future utilities or underground construction.

C. If importing of fill material is required for grading, proposed import material shall meet the requirements of Section D-3.1, and be free of hazardous materials ("contaminants") and rock larger than 3-inches (8 cm) in largest dimension. All import soils shall have an Expansion Index (EI) of 20 or less and a sulfate content no greater than 500 parts-per- million (ppm). Representative samples from a potential import source shall be given to the Resident Project Representative at least 15 full working days so that suitability of the import material can be determined and appropriate tests performed, before importing begins.

D. Backfill consists of the preparation and placement of materials for structural foundations, pipeline bedding, backfill for excavations and fill for roadways and embankments. In public rights-of-way, the requirements of the local agency having jurisdiction shall take precedence over these Specifications.

E. Backfill shall not be dropped directly upon any structure or pipe. Backfill shall not be placed around or upon any structure until the concrete has attained specified strength to withstand the loads imposed.   Backfill around water retaining structures shall not be placed until the structures have been tested and coated.

F. Material used in the work shall be uniform and shall contain no trash, wood, vegetation, sludge, peat and no rocks or clods larger than the size allowed by the Contract Documents. No material greater than 4 inches in any dimension shall be placed within 1 foot of any pipe, manhole or structure. Excavated material and material from borrow sites may be used where they meet the requirements of the Contract Documents. Blending or other processing may be necessary before a material is acceptable to the Resident Project Representative. Borrow sites shown on the drawings shall be excavated within the  limits  indicated.  All  costs  for  testing,  processing  and  transporting  materials  are included in the contract price.

G. Except for drainrock materials being placed in over-excavated areas or trenches, backfill shall be placed after all water is removed from the excavation.

3.12    PLACING AND SPREADING OF BACKFILL MATERIALS

A. Backfill materials shall be carefully placed, leveled and compacted in horizontal layers of the depth specified in the Contract Documents.   When compaction is achieved using mechanical equipment the layers shall be evenly spread in loose lifts not exceeding 8 inches in thickness so that when compacted each layer shall not exceed 6 inches in thickness.  Each layer of fill material shall cover the length and width of the area to be filled before the next layer of material is placed. The moisture content of the material shall be  controlled  and  water  shall  be  applied  as  necessary  to  achieve  the  specified compaction and for the prevention of dust nuisance. No fill or rock shall be placed on standing water in any excavation.

B. Fill under Structures:  The fill under structures, including fill to replace unsuitable material removed below the specified excavation or unauthorized over-excavation, shall be constructed in horizontal layers of select material not to exceed 8 inches in depth, or if under footings, the heights of the walls or footings shall be increased, or space shall be refilled with Class A concrete as specified in Section 03300, Cast-in-Place Concrete at the   expense   of   the   Contractor,   as   may   be   directed   by   the   Resident   Project Representative.   Any fill material used shall be compacted to a minimum relative compaction of 95 percent throughout.

Where the underlying soil has been disturbed by any activity, such as clearing and grubbing, it shall be compacted to a minimum relative compaction of 95 percent before placing any fill.

C. Structural Backfill:   All backfill around structures shall be made with select material or imported sand compacted to a minimum relative compaction of 95 percent up to the street zone.  Compaction shall be performed in horizontal layers not to exceed 8 inches in depth.  No backfill shall be placed against concrete structures until the 28-day concrete strength has been reached as specified spreading each layer shall be thoroughly mixed as necessary to promote uniformity of material in each layer.  Pipe zone backfill materials shall be manually spread around the pipe so that when compacted the pipe zone backfill will provide uniform bearing and side support.

D. Where the backfill material moisture content is below the optimum moisture content water shall be added before or during spreading until the proper moisture content is achieved.

E. Where the backfill material moisture content is too high to permit the specified degree of compaction the material shall be dried until the moisture content is satisfactory, at or slightly above optimum moisture content.

3.13    COMPACTION OF FILL, BACKFILL, AND EMBANKMENT MATERIALS

A. Each layer of fill shall be mechanically compacted using proper compaction equipment (not rubber tire or wheel rolling) to the specified percentage of maximum dry density. Equipment that is consistently capable of achieving the required degree of compaction shall be used and each layer shall be compacted over its entire area while the material is at the required moisture content.

The backfill shall be placed in horizontal layers of the specified depths or of such depths and compatible with the compacting equipment being used and the backfill material being placed. Each layer shall be evenly spread, properly moistened, or dried as necessary and compacted to the specified relative compaction. Any damage or displacement to pipes or structures as a result of the Contractor’s operation shall be repaired or replaced at the Contractor’s expense.

B. Fill on reservoir and structure roofs shall not be placed until at least 30 days after the concrete roof slab has been placed or the concrete has reached design strength. Equipment weighing more than 10,000 pounds when loaded shall not be used on a roof. A roller weighing not more than 8,000 pounds shall be used to compact fill on a roof.

C. Flooding, ponding, or jetting shall not be used to densify any fill materials with the exception of holes remaining from the extraction of H-beams, plates and piles.

D. Equipment weighing more than 10,000 pounds shall not be used closer to walls than a horizontal distance equal to the depth of the fill at that time, but not less than 5 feet. Hand operated power compaction equipment shall be used where use of heavier equipment is impractical or restricted due to weight limitations.

E. Compaction  Requirements:    The  following  compaction  test  requirements  shall  be  in accordance with ASTM D 1557.  Where agency or utility company requirements govern, the highest compaction standards shall apply.

F.



Location or Use of Fill Percentage of
Maximum Density  
Pipe zone backfill portion above bedding for flexible pipe 95  
Pipe zone backfill bedding and over-excavated zones under bedding/pipe for flexible pipe 95  
Pipe zone backfill portion above bedding for rigid pipe 95  
Pipe zone backfill bedding and over-excavated zones
under bedding/pipe for rigid pipe 95  
Final backfill, beneath paved areas or structures 95  
Final backfill, not beneath paved areas or structures 95  
Trench zone backfill 95  
Embankments See 3.15  
Embankments, beneath paved areas or structures 95  
Backfill beneath structures, hydraulic structures 95  
Backfill around structures, on reservoir or structure roof 95  
Topsoil 85  
Aggregate base 95

3.14    PIPE AND UTILITY TRENCH BACKFILL

A. Pipe Zone Backfill:  The pipe zone is defined as that portion of the vertical trench cross- section lying between a plane 12 inches below the bottom surface of the pipe, i.e., the trench subgrade, and a plane at a point 12 inches above the top surface of the pipe.  The bedding for flexible pipe is defined as that portion of pipe zone backfill material between the trench subgrade and the bottom of the pipe.  The bedding for rigid pipe is defined as that portion of the pipe zone backfill material between the trench subgrade and a level line which varies from the bottom of the pipe to the spring line as shown.

B. Bedding:  The bottom of a pipe trench excavation indicated on the Contract Documents is the foundation line where pipe-bedding material is placed. Contractor shall replace any material below the foundation line that has been disturbed or removed during excavation at no additional cost to the Owner.  Material shall be replaced with crushed rock bedding CAB CMB as directed by the Resident Project Representative.   Crushed rock bedding shall be mechanically consolidated to the satisfaction of the Resident Project Representative before laying pipe. Where poor soil is encountered, it shall be replaced as specified in Paragraph 3.4 of this Specification.

Bedding shall be provided for all sewers, drainage pipelines, and other gravity flow pipelines, unless otherwise specified or shown on the drawings.  For other pipelines the bedding may be omitted if all the following conditions exist.

1. The pipe bears on firm, undisturbed native soil, which contains only particles that will pass a one-inch sieve.
2.         The trench excavation is not through rock or stones.

3.         The trench subgrade soils are classified as suitable fill and backfill materials per
Subsection 2.

4. The trench subgrade soils have, as a maximum, a moisture content that allows compaction.

C. Where bedding is required, after compacting the bedding the Contractor shall perform a final trim using a string line for establishing grade, such that each pipe section when first laid will be continually in contact with the bedding along the extreme bottom of the pipe.

Pipe shall be carefully bedded as shown on the appropriate bedding detail.   Particular attention shall be given to the underside of the pipe and fittings to provide a firm bedding support  along  the  full  length  of  the  pipe.  The  Contractor  shall  be  responsible  for accurately shaping the pipe subgrade to fit the bottom of the pipe for a width of at least
0.4 times the pipe outside diameter.  Use of a drag template shaped to conform to the outer surface of the pipe will be required if other methods do not give satisfactory results.

Each bell and spigot joint shall be recessed in the bedding material in such a manner as to minimize loading on the bell of the pipe.  Backfilling shall be carried on simultaneously on each side of the pipe to prevent displacement.  Care shall be exercised in backfilling to avoid damage to the pipe.

D. The pipe zone shall be backfilled with the specified backfill material.  The Contractor shall exercise care to prevent damage to the pipeline coating, cathodic bonds, or the pipe itself during the installation and backfill operations.

E. Backfill at manholes over 60-inches in diameter shall be the same specified backfill material composition and compaction as in the adjacent pipe trench.  Backfill materials for manholes 60-inches and less in diameter shall be backfilled with sand-cement slurry per Subsection 2.1 K.

F. Trench Zone Backfill:  After the pipe zone backfill has been placed as specified above, and after all excess water has completely drained from the trench, backfilling of the trench zone may proceed.   The trench zone is defined as that portion of the vertical trench cross-section lying between a plane 12 inches above the top surface of the pipe and a plane at a point 30 inches below the finished surface grade, or if the trench is under pavement, 18 inches below the roadway subgrade.   If concrete or sand-cement slurry backfill are used, the Contractor shall secure the pipe to prevent flotation.

G. Final Backfill:   Final backfill is all backfill in the trench cross-sectional area within 18 inches of finished grade, or if the trench is under pavement, all backfill within 18 inches of the roadway subgrade.

3.15    EMBANKMENT CONSTRUCTION

A. Embankments and roadway fills shall mean all earth fills in holes, pits or depressions necessary to bring the final grade or pavement subgrade to the specified contours.
B. The area where an embankment is to be constructed shall be cleared of all vegetation, roots and deleterious materials.  Following this, the surface shall be moistened, scarified to a depth of 6 inches, and rolled or otherwise mechanically compacted.  Embankment fill material shall be placed and spread evenly in horizontal layers.   Each layer shall be moistened or aerated, as necessary.  Each layer shall not exceed 6 inches of compacted thickness.   The embankment fill and the scarified layer of underlying ground shall be compacted to 95 percent of maximum dry density.

C. Material  for  embankments  or  roadway  fills  may  consist  of  excavated  material  from structures or of a mixture of such excavated materials and materials borrowed by the Contractor from other approved sources.  The material shall have no rocks or clods larger than 6 inches and shall be compacted in 8-inch maximum lifts to a minimum relative compaction of 90 percent, up to the street zone.

D. If the ground surface is in a loose, uncompacted condition, it shall be compacted to a minimum relative compaction of 90 percent or to 95 percent if included in the street zone.

E. No material shall be placed beyond the sloping lines of embankment unless so ordered by the Resident Project Representative.  Compaction shall be as specified for each zone.

F.         When an embankment fill is to be made and compacted against fill slopes steeper than
4:1, the slopes of fills shall be horizontally benched to key the embankment fill to the underlying ground.  A minimum of 12 inches normal to the slope of the hillside or fill shall be removed and recompacted as the embankment fill is brought up in layers.  Material thus  cut  shall  be  recompacted  along  with  the  new  fill  material  at  the  Contractor’s expense. Hillside  or  fill  slopes  4:1  or  flatter  shall  be  prepared  in  accordance  with Paragraph A, above.

G. Where embankment or structure fills are constructed over pipelines, the first 4 feet of fill over the pipe shall be constructed using light placement and compaction equipment that does not damage the pipe.

END OF SECTION