Sec 839 Restore Drainage Functions.pdf

SECTION 839 – RESTORE DRAINAGE FUNCTION

1. DESCRIPTION

Work consists of log, limb, and debris removal; blading and shaping of the roadbed to restore drainage function. This work includes shoulders, ditches, drainage dips, leadoff ditches, turnouts, and intersections; cleaning drainage facilities; and removing washes and sloughs that inhibit drainage.

2. MAINTANENANCE REQUIREMENTS

a. General

1. The existing traveled way and shoulders, including turnouts unless otherwise ordered, shall be bladed and shaped to produce a surface which is uniform, consistent to grade, and crowned or cross-sloped as indicated by the character of the existing surface unless otherwise Marked on the Ground, to at least one half inch (1/2") per foot of width, but not more than three quarter inch (3/4") per foot of width. Surfacing materials shall be thoroughly loosened to a depth of no less than 2 inches or the depth of potholes or corrugations. Corrugations are washboarding and similar defects.

Scarification to facilitate cutting to the full depth of potholes or corrugations may be elected by the Contractor but will be considered incidental to blading. Scarification shall not go deep enough to cause contamination of the surfacing.

2. The Contractor shall apply water during blading when sufficient moisture is not present to prevent segregation.

3. Existing native, rock or aggregate surfaced drainage dips shall be cleaned and shaped incidental to blading to divert surface runoff to existing outlet devices, ditches and discharge locations.

4. The Contractor shall establish a blading pattern which provides a uniform driving surface, retains the surfacing on the roadbed and provides a thorough mixing of the materials within the completed surface width.

b. Drainage Facilities

Cleaning existing drainage facilities includes roadside drainage ditches, drainage dips, inlet and outlet ditches, overside drains and flumes, inverts and interiors of culverts, culvert catch basins, drop inlets, trash racks, and sediment basins. Slash and debris shall be scattered below the road in a uniform matter to prevent piles.

Drainage structures not included under this specification are bridges, cattle guards, and culverts over 72 inches in diameter.

c. Ditches, Lead Off and Roadside

Wood, rock, trees, brush and other debris shall be removed from ditches to provide unobstructed flow of water. Slash and debris (woody or organic) shall be scattered in such a manner as not to impede the flow of water. The backslope of ditches shall not be undercut by cleaning operations. Existing ditch blocks shall be restored, reshaped, and compacted as needed for effective drainage through culverts. Catch basins shall be cleaned of material above the invert of the culvert.

d. Dips (Also called intercepting dips or rolling dips)

Existing drainage dips shall be cleaned and the outslope gradient sufficiently restored to remove surface water from roadbed, conducting the water through drainage facilities.

e. Culverts

Inlet and outlet ends, as well as four feet inside each end, of existing culvert, shall be cleaned to provide unobstructed flow of water. Natural drain culvert channels shall be cleared of all down trees, limbs, stumps, brush, rocks and other debris, that restricts the flow of water, 6 feet in width for 15 linear feet at each end. Slash and debris (woody or organic) within 5 feet from the inlet shall be scattered in such a manner as not to impede the flow of water. The channel shall be shaped to natural streambed with constant grade at inlet and outlet ends.

f. Overside Drains and Flumes

Overside drains shall be cleaned of debris to provide an unobstructed flow of water. Debris (woody or organic) shall be scattered in such a manner as not to impede the flow of water.

g. Designed Earth Berms

Berm breaches of less than 5 cubic yards shall be filled, shaped, and compacted by wheel rolling. Fill material shall be located within 500 feet of breach or by ripping to the depth and width necessary to obliterate such defects; providing a smooth transition to adjacent satisfactory roadbed. Filling with loose material will not be acceptable.

h. Settlements

Settlements 12 inches or less in depth shall be scarified and then repaired by cutting from the roadbed on each end of the settled area, filling and wheel rolling the material into the settled area providing a smooth transition to adjacent satisfactory roadbed.

i. Washouts

Washouts in roadway of less than five cubic yards shall be filled and compacted by wheel rolling. Fill material shall be located within 500 feet of washout or as directed by the Contracting Officer.

3. METHOD OF MEASUREMENT

Measurement for maintenance will be “by the mile”, measured by slope distance along the centerline of the roadway. Measurement will be to the nearest one-tenth mile. No separate measurement will be made for any of the elements of work described in the foregoing

4. PAYMENT

Payment will be made for all units inspected and accepted at the unit price shown on the schedule of items.

Payments will be made under:

PAY ITEM PAY UNIT

839(01) Restore Drainage Function, Mile with water