7._Excavation_and_Fill.pdf

PROJECT QUUG 11-1016

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SECTION 31 23 00.00 20

EXCAVATION AND FILL

PART I - GENERAL

1.1 DESIGN REFERENCES: Provide the design and installation in accordance with the following references. This list is not inclusive and shall be used as a guide that shall be further developed by the Prime Contractor’s A-E hired firm. The publications are referred to in the text by the basic designation only.

ASOCIACIÓN ESPAÑOLA DE NORMALIZACIÓN Y CERTIFICACIÓN

UNA NORMA ESPAÑOLA (UNE)

UNE 103501 (1994), Geotechnical. Compaction Test. Modified Proctor

UNE 103503 (1995), Determination “in situ” of Density of Soil by the Sand

Method

1.2 DESCRIPTION: The work includes performing site preparation, excavation, filling, backfilling, compacting, and finished grading necessary to construct the finished grades indicated.

1.3 DEFINITIONS:

1.3.1 Backfill: Material used in refilling a cut or other excavation.

1.3.2 Compaction: The process of mechanically stabilizing a material by increasing its density at a controlled moisture condition. "Degree of Compaction" is expressed as a percentage of the maximum density obtained by the test procedure described in UNE 103501 and UNE 103503 for general soil types abbreviated in this specification as X% maximum density".

1.3.3 Excavation: The removal of soil or hard material to obtain a specified depth of elevation.

1.3.4 Fill: Specified material placed at a specified degree of compaction to obtain an indicated grade or elevation.

1.3.5 Lift: A layer or course of soil placed on top of a previously prepared or placed soil in a fill.

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1.3.6 Soil: The loose surface material of the earth resulting from the chemical and mechanical weathering of rock and organic material.

1.3.7 Subgrade: The bottom layer of material graded or otherwise prepared for supporting the addition of fill material, pavement courses, or a building slab.

1.3.8 Topsoil: In natural soil formations, the fine-grained, weathered material on the surface or directly below any loose or partially decomposed organic matter. Topsoil may be a dark-colored, fine, silty, or sandy material with a high content of well decomposed organic matter.

1.3.9 Unsatisfactory Material: Existing, in-situ soil or other material which can be identified as having insufficient strength characteristics or stability to carry intended loads in fill without excessive consolidation or loss of stability.

1.4 MINIMUM CONSTRUCTION SUBMITTALS: As determined during the design phase by the Designer of Record (DOR), additional submittals may be added to this outline list.

1.4.1 Fill material. Indicate gradation, origin quarry, compaction procedures and levels to be obtained as a minimum requirements.

1.5 DELIVERY AND STORAGE: Deliver and store materials in a manner to prevent contamination or segregation.

1.6 SITE CONDITIONS:

1.6.1 Utilities: Contact the Contracting Officer 72 hours prior to construction for the location of all existing underground utilities. Excavation made with power-driven equipment is not permitted within 60 cm of any known utility or subsurface construction. For work immediately adjacent to or for excavations exposing a utility or other buried obstruction use hand excavation. Support uncovered lines or other existing work as affected by the contract excavation until approval for backfill is granted by the Contracting Officer. Report damage to utility lines or subsurface construction immediately to the Contracting Officer.

PART 2 - PRODUCTS

2.1 FILL MATERIAL: Free of debris, roots, scrap material, vegetation, refuse, soft unsound particles, and deleterious or objectionable materials.

2.1.1 Soil Materials:

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2.1.1.1 Topsoil: Use salvaged topsoil. Provide additional topsoil from approved sources off the Base if salvaged topsoil is not sufficient to complete all indicated topsoil work.

2.1.2 Selected Fill: Shall conform to the following:

a. Organic material content lower than 0,2% (MO < 0,2%), as per UNE 103204.

b. Water soluble salts contents, including gypsum lower then 0,2% (SS < 0,2%), as per NLT 114.

c. Maximum size no higher than 100 mm (Dmax ≤ 100 mm).

d. Amount of material passing 0,40 UNE sieve lower or equal to 15% ( # 0,40 ≤ 15%), or in any case complies with every and all the following:

Amount of material passing 2 UNE sieve lower than 80% ( # 2 < 80%).

Amount of material passing 0,40 UNE sieve lower than 75% ( # 0,40 < 75%).

Amount of material passing 0,080 UNE sieve lower than 25% (# 0,080 < 25%).

Liquid limit lower than 30 (LL < 30), as per UNE 103103.

Plasticity index lower than 10 (IP < 10), as per UNE 103103 y

UNE 103104.

2.1.3 Adequate Fill: Shall conform to the following:

a. Organic material content lower than 1% (MO < 1%), as per UNE 103204.

b. Water soluble salts contents, including gypsum lower then 0,2% (SS < 0,2%), as per NLT 114.

c. Maximum size no higher than 100 mm (Dmax ≤ 100 mm).

d. Amount of material passing 2 UNE sieve lower than 80% ( # 2 < 80%).

e. Amount of material passing 0,080 UNE sieve lower than 35% (# 0,080 < 35%).

f. Liquid limit lower than 40 (LL < 40), as per UNE 103103.

g. Whenever liquid limit is higher than 30 (LL > 30), plasticity index shall be higher than 4 (IP > 4) as per UNE 103103 and UNE 103104.

PART 3 - EXECUTION

3.1 PROTECTION:

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3.1.1 Shoring and Sheeting: Provide shoring and sheeting where indicated or required to accomplish the following:

a. Prevent undermining of pavements, foundations and slabs.

b. Slope banks as indicated in project drawings where space permits; maximum slope 2:1 or provide shoring. For trenches to a depth of 1 m, maximum slope will be 1:1.

3.1.2 Dewatering: Dispose of surface water which may accumulate in open excavations, unfinished fills, or other low areas. Remove water by trenching where approved, pumping, or other methods to prevent softening of exposed surfaces. Collect and dispose of surface water.

3.1.3 Protection and Restoration of Surfaces: Protect newly graded areas from traffic, erosion, and settlements. Repair and reestablish damaged or eroded slopes, elevations or grades prior to acceptance. Protect existing streams, ditches and storm drain inlets from water-borne soil.

3.2 SURFACE PREPARATION:

3.2.1 Clearing and Grubbing: Unless indicated otherwise, remove trees, logs, stumps, shrubs, and brush within the limits of construction. Protect from damage trees and shrubs which are indicated to be saved or which are outside the limits of construction. Brush, refuse, stumps, roots, and timber shall become the property of the Contractor and removed from the Base.

3.2.2 Stockpiling Topsoil: Strip approved topsoil to a depth of 10 cm from the site where excavation or grading is indicated and stockpile separately from other excavated material. Locate topsoil so that the material can be used again for the finished grading. Protect and store in segregated piles until needed. Location of piles shall be coordinated with Government representatives to prevent dislocation that may result from wind.

3.3 EXCAVATION: Excavate to the contours, elevations, and dimensions indicated.

Keep excavations free from water while construction is in progress.

3.3.1 Shoring and Sheeting: Shore and sheet excavations with members sized and arranged to prevent injury to persons and damage to structures. Also arrange shoring and sheeting to preclude injurious caving during removal.

3.3.2 Trenches: Excavate to the dimensions indicated. Grade bottom of trenches.

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3.4 FILLING AND BACKFILLING: Fill and backfill to contours, elevations, and dimensions indicated. Compact each layer before placing next one.

3.4.1 General Fill and Backfill: Fill and backfill trenches with same material excavated to avoid noticeable discontinuities between the type of fill material used and surrounding material.

Place satisfactory material in horizontal lifts not exceeding 20 cm in loose depth. Do not place material on surfaces that are muddy, frozen, or contain frost. Compact with equipment well suited to the soil being compacted. Moisten or aerate material as necessary to provide the moisture content that will readily facilitate obtaining an adequate compaction. Compact each lift as specified before placing the overlaying lift. Backfill as rapidly as construction and acceptance of work permits.

3.4.2 Weather Limitations: Fill and backfill shall not be constructed when weather conditions detrimentally affect the quality of the finished course. Place fill and backfill only if the atmospheric temperature is above freezing in the shade and is rising. Do not construct fill and backfill in the rain or on saturated subgrades. If weather conditions are windy or hot with a high rate of evaporation, schedule the placement in cooler portions of the day and furnish equipment to add moisture to the fill or backfill during and after placement.

3.5 COMPACTION: Compact each layer or lift of material specified so that apparent density is adequate to project purpose.

3.6 FINISH OPERATIONS:

3.6.1 Site Grading: Grade to grades indicated within 3 cm. Grade areas to drain water away from manholes and to provide suitable surfaces for moving machines. Existing grades which are to remain but are disturbed by construction operations shall be restored.

3.6.2 Disposition of Surplus Material: Surplus or other soil material not required or suitable for filling and backfilling shall be wasted by disposition off the Base.

3.6.3 Protection of Surfaces: Protect newly graded areas from traffic, erosion, and settlements that may occur. Repair or reestablish damaged grades, elevations, or slopes prior to acceptance of work.

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