S-10-0296 912_excavation_std.doc

Section 912 -- Excavation and Embankment

Description

912.01 Work. Work consists of the excavation and placement of excavated material, regardless of its nature, from within the trailway or from other sources, except for material included under other pay items SHOWN IN THE SCHEDULE OF ITEMS.

Includes excavation, embankment, and backfill construction required to shape and finish the trailbed, ditches, back-slopes, and fill slopes. Also includes excavation and embankment work required to construct talus and rubble rock sections.

Materials

912.02 Requirements. Use materials meeting the requirements of Section 961.

Construction

912.03 Use and Disposal of Excavated Material. Conserve and use all suitable material for specified work. Conserve excess excavated rock suitable for specified project work and use in place of materials from designated sources.

Remove all duff and debris from within trailway limits unless otherwise SHOWN ON THE DRAWINGS.

Scatter excess and unsuitable material beyond the downslope edge of the trailway. Do not obstruct drainage or create piles, berms, or windrows of debris. This includes any material removed in the grubbing operation and deposited in the same area.

912.04 Trailway Excavation and Embankment. Minor deviations of ±1 foot in vertical alignment and 2 feet in horizontal alignment with smooth transitions of at least 20 feet on each side of the deviation are acceptable unless otherwise SHOWN ON THE DRAWINGS. Make necessary adjustments of horizontal or vertical alignment, within the tolerances, to produce the designed trailway section and balance earthwork. Such adjustments shall not be considered as changes.

Construct embankments with suitable compacted material. Compact all disturbed soil within the trailbed area.

Remove any rock within or above the backslopes that is unstable. Use or dispose of rock in accordance with Subsection 912.03.

Leave the finished slope in a uniform and roughened condition.

912.05 Trailbed Finish. Fill holes with suitable material, compact, and cut high points to provide a uniform trailbed finish.

912.06 Talus or Rubble Rock Sections. Through talus or rubble rock slide areas, fill all voids with suitable material to the depth SHOWN ON THE DRAWINGS. Use cap rocks that are a minimum of ¾-cubic foot in size and have a length of at least twice their width. At least 50 percent of all hand-placed outer rocks should be a minimum of 1 cubic foot in size. Construct tread by building out rather than by removing material from the inner bank.

912.07 Retaining Walls. Trailbed sections utilizing rock retaining walls may be constructed in place of full-bench construction. Construct rock retaining walls in accordance with Section 935.

912.08 Drainage. Install the permanent drainage structures NOTED ON THE TRAIL LOG or temporary drainage upon excavation of trail to grade.

Construct outlet ditches for drain dips where NOTED ON THE TRAIL LOG or as necessary to provide drainage. Where NOTED ON THE TRAIL LOG or where outlet ditches will not drain within 20 feet, construct an 18-inch diameter drain sump to a minimum depth of 24 inches and located at least 5 feet from edge of trailbed. Fill sump with coarse rock.

Construct side ditches to be free of loose rocks, roots, sticks, and other obstructions.

912.09 Geotextiles. Where NOTED ON THE TRAIL LOG place geotextile fabric flat and parallel to centerline of the trail before placing backfill or embankment. Overlap geotextiles a minimum of 24 inches.

Measurement

912.10 Method. Measure the quantities in accordance with Section 906.

Payment

912.11 Basis. Pay for the accepted quantities in accordance with Section 906 at the contract unit price for each PAY ITEM SHOWN IN THE SCHEDULE OF ITEMS.

The following will be considered incidental to the PAY ITEMS SHOWN IN THE SCHEDULE OF ITEMS and extra payment will not be given:

(a) Outlet ditches, drain sumps, geotextile fabric, borrow, and talus or rubble rock sections.

(b) Retaining walls on the lower side of the trailbed constructed in place of full-bench construction.

Make payment under:

PAY ITEM

PAY UNIT

912(01) Excavation

LF

912(02) Heavy Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LF

912(03) Ditch

LF

912(04) Ditch Re-construction

LF

912(05) Shallow Stream Ford- Rock. . . . . . . . . . . . . . . . . . . . . . . . . . . . EA

912(06) Shallow Stream Ford- Native Log. . . . . . . . . . . . . . . . . . . . . . . . . EA

912-1 (12/10/2009)