Section 02100 - Timber Retaining Walls and Gravel Pad.doc

SECTION 02100

Timber retaining walls & gravel pad

PART 1 - GENERAL

1.1 SUMMARY

This work shall consist of the construction of timber retaining walls around designated permitters of the Ramada shelters. Timber wall shall be stabilized with #3 rebar & 1/2" x 12” Lag Bolts to maintain stability and structural integrity. This work will also include the construction of a gravel drainage pad between the existing Ramada concrete slab and the new retaining wall.

1.2 MEASUREMENT

A. Timber ties will be measured per unit. One unit is defined as one (1) 7”x9”x8’ tie.

B. Gravel will be measured in cubic yards.

C. #3 Rebar & 1/2" x 12” Lag Bolts will be incidental to Timber Ties in item A.

D. Quantities of timber ties will be the number of individual ties utilized for the construction of one (1) wall. The phrase one (1) wall is defined as the entire wall designated for each respective shelter.

Quantities of gravel will be the total volume of gravel (Cubic Yards) needed to construct the entire gravel pad designated for each respective shelter.

E. The actual quantities will be paid for at the contract unit price for each pay item shown in the Schedule of items. Actual quantities are defined as the actual physical quantity of material needed to accomplish the work outlined in this section to deliver a product that is both safe and acceptable. If construction requires a higher quantity of material than what has been shown in the Schedule of items, contractor shall coordinate with the CO for approval prior to construction and/or purchasing and billing.

PART 2 – PRODUCTS

F. The timbers shall be treated timber ties. Ties shall be treated with Copper Nathenate. Nominal dimension shall be 7” x 9” x 8’. The COR will inspect and approve all ties prior to construction. Should the Contractor supply ties that are deemed non-acceptable per the COR, additional ties shall be purchased and supplied at no additional cost to the Federal Government.

G. Gravel shall be 2” Seepage Gravel. Gravel shall be “washed.”

H. Rebar shall be a minimum of #3 rebar.

I. Lag Bolts shall be 1/2" x 12” Galvanized Steel bolts with 1/2" washers.

PART 3 – EXECUTION

1.3 Timber retaining walls

A. All debris, trees, stumps, roots, and other protruding vegetative material within the area of retaining wall, not DESIGNATED to remain, shall be cleared, grubbed, removed, and disposed of only with COR approval.

B. Contractor shall be responsible for ensuring the subgrade is compacted, level and suitable for the placement of timber ties.

C. Contractor shall stack timbers in a staggered manner to ensure individual ties interlock with each other (rows below and above).

D. Contractor shall install # 3 rebar at 4-foot intervals +/- 6” along the base row of retaining wall. First and last stakes shall not exceed a horizontal distance of 1 FT from outermost edge of wall on both sides. Stakes shall extend to a minimum of 1 FT into existing subgrade. Contractor shall pre-drill ties prior to installation of rebar with a 1/4" drill bit.

E. For all rows above base row, Contractor shall anchor all ties to the row below with 0.5” x 12” Galvanized Steel Lag Bolts complete with 0.5” washers. Lags shall be installed at 4-foot intervals +/- 6” throughout the entire length of wall. First and last lags shall not exceed a horizontal distance of 1 FT from outermost edge of wall. Lag bolts shall be countersunk 0.5” into ties. Contractor shall pre-drill ties prior to installation of lag bolts with a 3/8” drill bit.

F. Where one wall ties into another perpendicularly, corners shall be notched & staked with # 3 rebar. Rebar shall be countersunk 0.5” below wall finish elevation and extend to a minimum of 1 FT into existing subgrade. Contractor shall pre-drill ties prior to installation of rebar with a 1/4" drill bit.

G. All recessed holes shall be sealed with caulking.

H. Length & Height of walls vary depending on respective shelter. Refer to construction drawings.

I. Contractor shall be responsible to ensure top of wall is level with the existing Ramada Shelter concrete slab.

J. Contractor shall place over excavated material associated with excavation for Gravel Pads on the outer side of retaining wall for further stabilization of wall as shown in the construction drawings.

1.4 Gravel pad

A. Gravel pad shall be 4 feet wide. Length & Depth of pads vary depending on respective shelter. Refer to construction drawings.

B. Contractor shall be responsible to ensure top of gravel pad is level with the existing Ramada Shelter concrete slab.

PART 4 – MEASUREMENT & PAYMENT

4.1

MEASUREMENT & PAYMENT

A.

Payment for the timbers shall be per unit to include associated #3 Rebar and Lag Bolts. (EA).

B.

Payment for gravel shall be per cubic yard (CY).

END OF SECTION 02100

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TIMBER RETAINING WALLS AND GRAVEL PAD