essay 2-3 pages Cost & Estimating

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CSMT 441

Site Works-Excavation

Lecture 6

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Division 2 – Existing Conditions

• Surveys

• Geotechnical Investigation

• Site Demolition

• Transportation and Disposal of Hazardous Materials

• Asbestos Remediation

• Lead Remediation

• Mold Remediation

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BCN 5618 5

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Division 31 - Earthwork

• Site Clearing

• Earth Stripping & Stockpiling

• Excavation and Fill

• Erosion and Sedimentation Control

• Dewatering

• Excavation Support/Protection

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Earthwork

• Specifications

– Excess excavated materials (how far must it be

hauled)

– Clearing and grubbing (who is responsible?)

– Topsoil (must it be stockpiled for future use?

Where?)

– Trenching for mechanical and electrical work

(who is responsible for?)

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Type of Soil

• Soil Borings

• Visiting the site

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Calculating Excavation

• Unit (cubic yard, 1 cy = 27 cf)

• Swell and shrinkage

– 1.0 cy in natural condition (bank yard) = 1.25

cy after digging (loose yards) = 0.9 cy after

compaction (compacted yards)

– swell factor = loose yard/bank yard

– shrinkage factor = compacted yard/bank yard

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Equipment

• Minimize hand digging and shoveling

• Select suitable equipment

– The bulldozer is suitable for moving soil for short distances only up to about 150 ft.

– Rubber-tired scrapers are excellent for earthmoving up to 1.5 miles.

– Dump trucks are used for hauls beyond the economic range of rubber-tired scrapers.

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Equipment Selection

• The sheeps foot roller is suitable for compacting very

cohesive soil in lifts of about 6 in or less.

• Vibration is an excellent means of compacting sands,

and vibratory rollers are designed to use this method.

It is normally a steel wheel roller with an auxiliary

device to provide vibration to the roller.

• Pneumatic tired rollers, impart a kneading action as

well as vertical pressure on the soil being compacted.

They are good for sands, gravels, or those materials

in combination with some cohesive material.

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New site grades and rough grading

• Cutting and filling to reshape the grade

– Cross Section Method

• For building sites and parking areas

• Dividing the site into a grid and determining the cut

or fill for each of the grids

– Average End Area

• For long narrow tracts such as roads

• The site is divided into stations

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Labeling Convention

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BCN 5618 17

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Fill Volume (Grid 13)

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Cut Volume (Grid 40)

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Cut and Fill (Grid 10)

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New site grades and rough grading

• Cutting and filling to reshape the grade

– Average End Area

• For long narrow tracts such as roads.

• The site is divided into stations;

• a profile at each station line is drawn;

• the cut or fill area of two adjacent profiles is

averaged and multiplied by the distance between the

two stations.

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Road Site Plan

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Topsoil Removal

• Unit (cubic yard)

• Depth

• Stockpile location

• Clearance

– buildings: 5'

– walks, roadways, and parking areas: 1' to 2'

• Equipment: a bulldozer or a front-end loader

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General Excavation

• Removal of all types of soil that can be handled in

fairly large quantities using power equipment

(basement, cut for a highway, ..)

• Add 1' on all sides of the footing to allow workers

to install and remove forms

• Allow for the sloping of the banks (angle of

repose)

• What must be done with the excess excavation?

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Typical Excavation

BCN 5618 30

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Special Excavation

• Portions of the work that require hand

excavation or special equipment other than

general excavation (footing holes, small

trenches)

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Backfilling

• Volume of excavation minus volume of the

building within the area of excavation.

• Tamping or compaction is required

• Soil shrinkage must be considered

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Backfill Section

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Excess and Borrow

• If volume of cut > volume of fill, excess materials must be

disposed off

• If volume of fill > volume of cut, shortage materials must

be borrowed

• Topsoil is not included in this comparison.

• Consider soil swell for excess materials

• Determine the distance excess materials must be hauled

away

• Consider shrinkage for borrowed materials

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Support of Excavation Systems

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BCN 5618 36

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Division 32 – Exterior Improvements

• Base Course

• Flexible Paving

• Rigid Paving

• Landscaping

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Spreading Topsoil, Finish Grade

• Stockpiled topsoil is usually placed over

the rough grade to make it a finish grade. If

the volume is not sufficient, it will have to

be purchased.

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Asphalt Paving

• Unit (SY or Ton)

• Determine the surface area to be paved (SF)

• Determine the compacted thickness of each

course and type of materials required (inches)

• Use the following table to find the tonnage of

asphalt, granular materials, and subgrade

materials.

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Approximate Asphalt and

Granular Material Tonnage

BCN 5618 42

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Landscaping

• Seeding and fertilizing (type, no. of # per

square, area to be covered)

• Sodding (type, area to be filled)

• Trees and shrubs (number, size, and

species)

• Maintenance of landscaping and guarantee

period