EXCAVATING, BACKFILLING, AND COMPACTING

EXCAVATING, BACKFILLING, AND COMPACTING


PART 1 -- GENERAL

1.01     SUMMARY

Division 0, Contract requirements and Division 1, General Conditions apply to this section.

1.02     DESCRIPTION

Work included:  Rough grading and compaction of the site and building pad areas to a tolerance of ±0.10 of a foot.  Excavate for foundations, backfill and compact as necessary and fine grade the site to the elevations shown on the Drawings, as specified herein, and as needed to meet the requirements of the construction shown in the Contract Documents.

1.03     QUALITY ASSURANCE

A. Use adequate numbers of skilled workmen who are thoroughly trained and experienced in the necessary crafts and who are completely familiar with the specified requirements and the methods needed for proper performance of the work of this Section.

B. Use equipment in size, capacity, and numbers to accomplish the work of this Section in a timely manner.

C. In addition to complying with requirements of governmental agencies having jurisdiction, comply with the directions of the Soils Engineer.

1.04     SUBSTITUTIONS

Substitutions will be considered per Article 6.4 of the General Conditions.

1.05     SUBMITTALS

In accordance with Article 6.13 of the General Conditions.


PART 2 -- PRODUCTS

2.01     SOILS MATERIALS

Fill and backfill materials:

1. Provide soil materials free from organic matter and deleterious substances, containing no rocks or lumps larger than 2" in their greatest dimension, and equal to the on-site material.

2. Fill material is subject to the acceptance of the Soils Engineer, and is that material removed  from  excavations  or  imported  from  off-site  borrow  areas,  predominantly granular, non-expansive soils free from roots and other deleterious matter.

3. Imported materials shall be tested and accepted by the Soils Engineer before being brought to the site.

4. Cohesion-less  material  used  for  structural  backfill:    Provide  sand  free  from  organic material and other foreign matter, and as accepted by the Soils Engineer.

5. Provide  granular  base  under  building  slabs.     Fine  aggregate  shall  comply  with requirements of Section 03300 of these Specifications.

2.02     WEED KILLER

A. Provide a dry, free-flowing, dust-free chemical compound containing not less than 30% sodium chlorate or a chlorpyritos or Permethrin  compound, non-flammable, not creating a fire hazard when applied in accordance with the manufacturer's recommendations, soluble in water, and capable of being spread dry or in solution.   Chemical shall comply with Section 815-3.6 of FMA MP 5.

B.         Acceptable products:

1.         "Duraban TC":

2.         "Dragnet":

3.         An approved equal will be accepted if substitution submitted according to Section
01340.

2.03     OTHER MATERIALS

Provide  other  materials,  not  specifically  described  but  required  for  a  complete  and  proper installation, as selected by the Contractor subject to the acceptance of the Landscape Architect.


PART 3 -- EXECUTION

3.01     SURFACE CONDITIONS

A.         Examine the areas and conditions under which work of this Section will be performed.
Correct conditions detrimental to timely and proper completion of the Work.   Do not proceed until unsatisfactory conditions are corrected.

B. If the Contractor encounters conditions at the site that (a) are materially different from those indicated in the contract plans or in specifications, or (b) could not have been reasonably anticipated as inherent in the work of the character provided in the contract, the Contractor shall immediately notify the Owner verbally and in writing within 24 hours. This notification shall be a condition precedent before any negotiations for "changed or differing site conditions" can proceed.   If the Owner determines that conditions do materially so differ and cause an increase or decrease in the Contractor's cost of, or the time required for, performance of any part of the work under this contract, then negotiations shall commence between Owner and Contractor to provide equitable adjustment to Owner or Contractor resulting therefrom.

3.02 PROCEDURES

A. Utilities:
1. Unless shown to be removed, protect active utility lines shown on the Drawings or otherwise made known to the Contractor prior to excavating.   If damaged, repair or replace at no additional cost to the Owner.

2. If active utility lines are encountered, and are not shown on the Drawings or otherwise  made  known  to  the  Contractor,  promptly  take necessary steps to assure that service is not interrupted.

3. If  existing  utilities  are  found  to  interfere  with  the  permanent  facilities  being constructed under this Section, immediately notify the Architect and secure his instructions.

4. Do not proceed with permanent relocation of utilities until written instructions are received from the engineer.

B.         Protection of persons and property:

1. Barricade open holes and depressions occurring as part of the Work, and post warning lights on property adjacent to or within public access.

2. Operate  warning  lights  during  hours  from  dusk  to  dawn  each  day  and  as otherwise required.

3. Protect  structures,  utilities,  sidewalks,  pavements,  and  other  facilities  from damage caused by settlement, lateral movement, washout, and other hazards created by operations under this Section.

C.         De-watering:

1. Remove all water, including rain water, encountered during trench and sub- structure work to an approved location by pumps, drains, and other approved methods.

2.         Keep excavations and site construction area free from water.

D. Use  means  necessary  to  prevent  dust  from  becoming  a  nuisance  to  the  public,  to neighbors, and to other work being performed on or near the site.

E.         Maintain access to adjacent areas at all times.

3.03     EXCAVATING

A. Perform excavating of every type of material encountered within the limits of the Work to the dimensions and elevations indicated and specified herein.

B. Excavated materials:   Transport to, and place in, fill or embankment areas within the limits of the Work; dispose of such excess material away from the site in a location arranged and paid for by the Contractor.

C. Excavate and backfill in a manner and sequence that will provide proper drainage at all times.

D.         Unauthorized excavation:

1. Unauthorized  excavation  consists  of  removal  of  materials  beyond  indicated subgrade elevations or dimensions without specific instruction from the Architect or the Soils Engineer.

2.         Under footings, foundations, or retaining walls:

a. Sub-excavate and recompact earth materials in the affected area as directed by the Soils Engineer.

b. When acceptable to the Soils Engineer, lean concrete fill may be used to bring the bottom elevation to proper position.

3. Elsewhere,  backfill  and  compact  unauthorized  excavations  as  specified  for authorized excavations, unless otherwise directed by the Soils Engineer.

E.         Stability of excavations:

1.         Slope sides of excavations to 1:1 or flatter, unless otherwise directed by the Soils
Engineer.

2. Shore and brace where sloping is not possible because of space restrictions or stability of the materials being excavated.

3. Maintain sides and slopes of excavations in a safe condition until completion of backfilling.

F.         Shoring and bracing:

1. Provide materials for shoring and bracing as may be necessary for safety of personnel, protection   of   work,   and   compliance   with   requirements   of governmental agencies having jurisdiction.

2. Maintain  shoring  and  bracing  in  excavations  regardless  of  the  time  period excavations will be open.

3.         Carry shoring and bracing down as excavation progresses.

G.         Excavating for structures:
1.         Conform to elevations and dimensions shown within a tolerance of 0.10 ft.

2. Where concrete is anticipated to be placed directly against earth surfaces, widen excavations by one inch at each contact surface beyond that specified on the plans.

3. In excavating for footings and foundations, take care to create accurate and straight planes and shapes.

a.         Excavate by hand tools to final grade where necessary.

b. Trim bottoms to required lines and grades to leave solid base to receive concrete.

H.         Excavating for pavements:

1. Cut surface under pavements to comply with cross-sections, elevations, and grades.

3.04 FILLING AND BACKFILLING
A. General:
1. For each classification listed below, place acceptable soil material in layers to required subgrade elevations.

2.         In excavations, use satisfactory excavated or borrowed material.

3.         Under asphalt pavements, use subbase materials.

B.         Placing and compacting:
1.         Place backfill and fill materials in layers not more than 8" in loose depth.

2. Before compacting, moisten or aerate each layer as necessary to provide the optimum moisture content.

3.         Compact each layer to required percentage of maximum density for area.

4. Do  not  place backfill or fill  material  on  surfaces  that  are muddy, frozen, or containing frost or ice.

5. Place  backfill  and  fill  materials  evenly  adjacent  to  structures,  to  required elevations.

6. Take care to prevent wedging action of backfill against structures by carrying the material uniformly around the structure to approximately the same elevation in each lift.

C. Backfill excavations as promptly as progress of the Work permits but not until completion of the following:

1. Acceptance  of  construction  below  finish  grade  including,  where  applicable, damp-proofing and waterproofing.

2.         Inspecting, testing, approving, and recording locations of underground utilities.

3.         Removing concrete formwork.

4. Removing  shoring  and  bracing,  and  backfilling  of  voids  with  satisfactory materials.

5.         Removing trash and debris.

6.         Placement of horizontal bracing on horizontally supported walls.

3.05     COMPACTING

A. Control  soil  compaction  for  any  areas  disturbed  during  construction  to  provide  the minimum percentage of density specified for each area as determined according to ASTM D1557.   Soils Engineer’s recommendations found in the Soils Report will take precedence.

B. Provide  not  less than the following  maximum  density of soil material compacted at optimum moisture content for the actual density of each layer of soil material in place, and as approved by the Soils Engineer.

1. Structures:  Compact each layer of fill and material or backfill material at 90% of maximum density.

2.     Lawn and unpaved areas:

3. Compact the top 8" of subgrade and each layer of fill material or backfill material at 90% of maximum density.

4.         Compact the upper 12" of filled areas, or natural soils exposed by excavating, at
85% of maximum density.

5. Paving:    Compact  each  layer  of  fill  material  or  backfill  material  at  95%  of maximum density.

C.         Moisture control:

1. Where subgrade or layer of soil material must be moisture-conditioned before compacting, uniformly apply water to surface of subgrade or layer of soil material to prevent free water appearing on surface during or subsequent to compacting operations.

2. Remove and replace, or scarify and air dry, soil material that is too wet to permit compacting to the specified density.

3. Soil material that has been removed because it is too wet to permit compacting may be  stockpiled or spread and allowed to  dry.   Assist drying by discing, harrowing, or pulverizing until moisture content is reduced to a satisfactory value as determined by moisture-density relation tests approved by the Soils Engineer.

3.06 FINE GRADING
A. General:
1. Uniformly grade the areas within limits of grading under this Section, including adjacent transition areas.

2.         Smooth the finished surfaces within specified tolerance.

3. Compact with uniform levels or slopes between points where elevations are shown on the Drawings, or between such points and existing grades.

B.         Grading outside building lines:

1. Grade areas adjacent to buildings to achieve drainage away from the structures, and to prevent ponding.

2.         Finish the surfaces to be free from irregular surface changes, and:

a. Shape the surface of areas scheduled to be under walks to lines, grade, and cross-section, with finished surface not more than 0.10 ft. above or below the required subgrade elevation.

b. Shape the surface of areas scheduled to be under pavement to line, grade, and cross-section, with finished surface not more than 0.05 ft. above or below the required subgrade elevation.

3.07     MAINTENANCE

A.    Protection of existing graded areas:

1. Protect existing graded areas from traffic and erosion, and keep free from trash and weeds;

2. Repair  and  re-establish  grades  in  settled,  eroded  and  rutted  areas  to  the specified tolerances.

B. Where completed compacted areas are disturbed by subsequent construction operations or adverse weather, scarify the surface, reshape, and compact to the required density prior to further construction.