atch 1 2225 Sub Base.pdf

Sub-Base, Pit Run, & Classified Backfill FA5000-12-R-0001 Attachment 1

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1. SCOPE:

1.1 This section covers the excavation of existing unsuitable soils, and the placement and compaction of sub-base materials and classified fill/backfill for roads and airfields.

2. REFERENCED SPECIFICATIONS:

2.1 Alaska Department of Highways "Standard Specification for High Construction," 2004, is included as part of these specifications to the extent noted hereinafter. Where the referenced specifications conflict with the requirements noted in these specifications, these specifications will take precedence. All testing required by the referenced specifications will be done by the Contractor.

3. EXCAVATION:

3.1 Excavation of the existing soil shall conform to the line items “Remove Unsuitable Soil”, “Remove Unusable Soil”, and “Remove Existing BASE or Sub-base”.

4. CLASSIFIED FILL / PIT RUN:

4.1 Classified material shall be crushed

, WG or PG soil, non-frost susceptible materials (no more than 6.5 percent passing the #200 sieve), consisting of sands, gravels and fines, containing not more than 40 percent by weight passing the #4 sieve with a maximum aggregate size of 2" or accepted equal by the government’s project engineer / project inspector.

4.2 Pit Run material

typically consists of sands, gravels, and fines with a maximum aggregate size of 6” to 8” depending on required lift thickness, or accepted equal by the government’s project engineer / project inspector as taken directly from the mining operation without further processing.

Pit run material typically shall be non-frost susceptible, but in accepted situations may be S1 or S2 frost susceptible. When reject material is used for pipe bedding it is paid as pit run material.

5. SUB-BASE:

5.1 New sub-base shall be non-frost susceptible (no more than 6.0 percent passing the #200 sieve), and shall conform to the gradation requirements for Sub-base as shown in Table 1 below, or accepted equal by the government’s project engineer / project inspector. The sub-base may be either crushed or uncrushed. Reject material from the crushing operation shall not be used for sub-base unless accepted otherwise by the government’s project engineer / project inspector.

Pavements - IDIQ

FXSB 11-2102

Section 2225

Sub-Base, Pit Run, & Classified Backfill

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TABLE 1

Aggregate Gradation - SUB-BASE

* 50% max passing the #10 sieve is a UFGS requirement to meet 50 CBR.

** 40% max passing the #4 sieve is a more stringent local borrow pit requirement to meet compaction and drainage requirements.

6. SUB-BASE / CLASSIFIED / PIT RUN PLACEMENT:

6.1 Shall conform to Section 203-3.01 through 203-3.04 of the Alaska Department of Highways Specification. The depth of compacted sub-base, classified fill/backfill, and/or pit run shall be indicated on the delivery order. The sub-base, classified fill/backfill, or pit run lift thickness shall not exceed 12 inches for roads and shall not exceed 8 inches for airfields, unless approved otherwise by the government’s project engineer / project inspector.

7. COMPACTION:

7.1 Compaction of the existing sub-grade, the existing sub-base, the re-use of the existing base as sub-base, the new classified material, the new pit run, and the new sub-base for roadwork shall be 96 % of the maximum density.

7.2 Compaction of the existing sub-grade, the existing sub-base, the re-use of the existing base as sub-base, the new classified material, the new pit run, and the new sub-base for airfields shall be 98% of the maximum density.

7.3 Densities shall be determined in accordance with ASTM D 1557 (Modified Proctor).

SUB-BASE SUB-BASE SUB-BASE

1” minus" 2” minus" 3” minus"

Sieve Sieve Percent Percent Percent Size Size Passing Passing Passing 3” 75 mm 100 2” 50 mm 100 1” 25 mm 100 --- ---

3/4” 19 mm --- #4 4.75 mm 40 max** 40 max** 40 max**

#10 50 max* 50 max* 50 max* #40 1.18 mm --- --- --- #200 0.075 mm 2-6 2-6 2-6

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7.4 The field density shall be determined using ASTM D 2922 (Nuclear Method). Testing shall be at the responsibility of the Contractor. The field density and gradation tests shall be performed on the existing sub-grade, the existing sub-base, the new classified material, the new pit run, and the new sub-base for each lift placed.

7.5 Tests shall be performed by the independent quality controller and taken at random locations.

7.6 When required by the project engineer, additional tests shall be taken at locations selected by the contracting officer or his designated technical representative. When an area fails the field density test, the Contractor shall further compact the area and retest, at the Contractor's expense, until the area has attained the required field density.

8. TESTING REQUIREMENTS:

New Sub-base/Classified Material/Pit Run

8.1 The aggregate gradation tests and the density tests shall be performed on the new sub-base, new classified material, and new pit run per lift in a lot size as indicated below:

8.1.1 The aggregate gradation tests shall be performed in the field on the new in-place material at the rate of 1 field gradation test per 1000 tons

8.1.2 The aggregate density tests shall be performed in the field on the new in-place material at the rate of 2 field density tests per 500 tons

(compacted in place).

8.1.3 The aggregate gradation tests and density tests on the new sub-base are included in the line item “Base Course/Sub-base Testing”.

Re-Use Existing Base as Sub-base

8.2 The gradation and density tests shall be performed on the Re-Use Existing base as Sub-base per top 6” lift in a lot size as indicated below:

8.2.1 The aggregate gradation tests shall be performed in the field on the Re-Use Existing Base as Sub-base at the rate of 1 field gradation test per 500 CY

8.2.2 The aggregate density tests shall be performed in the field on the Re-Use Existing Base as Sub-base at the rate of 2 field density tests per 250 CY

8.2.3 The aggregate gradation tests and density tests on the Re-Use Existing Base as Sub-base are included in the line item “Base Course/Sub-base Testing”.

Existing Sub-base/Sub-grade

8.3 The gradation and density tests shall be performed on the existing sub-grade and existing sub-base per top 6” lift in a lot size as indicated below:

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8.3.1 The aggregate gradation tests shall be performed in the field on the existing sub-grade and sub-base at the rate of 1 field gradation test per 5,000 SY

8.3.2 The aggregate density tests shall be performed in the field on the existing sub-grade and sub-base at the rate of 2 field density tests per 2,500 SY

8.3.3 The aggregate gradation tests and density tests on the existing sub-grade and existing sub-base are included in the line item “Base Course/Sub-base Testing”.

9. SUBMITTALS:

9.1 Provide density test results and gradation test results to the project engineer/project inspector.

10. SURFACE PREPARATION OF EXISTING SUB-BASE/SUB-GRADE:

10.1 The line item for the “Surface Preparation of Existing Sub-base/Sub-grade” includes the surface preparation (grading and compacting) of gravel or dirt shoulders on airfields or roads. This line item also includes the dozing, grading, and compacting of new drainage ditches. Excess dirt will be blended into the adjacent on-site landscape.

10.2 For payment, “new drainage ditches” will be counted as 2.0 square yards (SY) of “Surface Preparation of Existing Sub-base/Sub-grade” for each 1.0 square yards (SY) of “new drainage ditches” measured in place.

11. INDEPENDENT QUALITY CONTROL (IQC):

11.1 The IQC shall establish and maintain quality control of the work covered under this section for each delivery order with sub-base, classified material, or sub-grade line items to ensure compliance with the contract requirements, including but not limited to the items listed below:

11.1.1 Gradations of aggregates meet the specifications, work areas are properly compacted, and thickness measurements are performed.

11.2 The services of the IQC are in the line item “IQC for Base Course/Sub-base Testing”. The required lots or sub lots for quality control or inspection on each work area for new sub-base/classified material and existing sub-base/sub-grade will be delineated on the issued delivery orders. See 1020 para 15 for additional IQC requirements.

12. UNIT OF MEASUREMENT AND PAYMENT: Per the Bid Schedule and Section 1020.

End of Section