312323-Backfill.pdf

Steam Supply and Condensate Backfill Return Piping Replacement 312323-1 PGRU, Geneva, NY

SECTION 312323

BACKFILL

PART 1 GENERAL

1.1 SUMMARY

A. Section Includes:

1. Fill under grass areas.

2. Fill under and around concrete HPS tunnel.

3. Fill for over-excavation.

B. Related Sections:

1. Section 310516 - Aggregate.

2. Section 312316 - Excavation and Fill.

3. Section 329219 - Seeding and Soil Supplements.

1.2 REFERENCES

A. American Association of State Highway and Transportation Officials:

1. AASHTO T180 - Standard Specification for Moisture-Density Relations of Soils

Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop.

B. ASTM International:

1. ASTM D1556 - Standard Test Method for Density of Soil in Place by the Sand-

Cone Method.

2. ASTM D1557 - Standard Test Method for Laboratory Compaction

Characteristics of Soil Using Modified Effort (6,000 ft-lbf/ft3 (2,700 kN-m/m3)).

3. ASTM D2922 - Standard Test Method for Density of Soil and Soil-Aggregate in

Place by Nuclear Methods (Shallow Depth).

1.3 SUBMITTALS

A. Product Data: Submit data for geotextile fabric indicating fabric and construction.

PART 2 PRODUCTS

2.1 FILL MATERIALS

A. Subsoil Fill: Type S1 as specified in Section 310516.

B. Topsoil Fill: Type S2 as specified in Section 329219.

C. Crushed No. 1 Stone: Type A1 as specified in Section 310516.

D. Item 4: Type A4 as specified in Section 310516.

Return Piping Replacement 312323-2 PGRU, Geneva, NY

E. Concrete: Structural concrete as specified in Section 033000.

2.2 ACCESSORIES

A. Filter Fabric: (Separation, Drainage, Erosion & Sediment Control): Amoco CEF 4545, CEF 4551; Exxon Chemical Co. GTRF 150 EX; Mirafi Inc. 140N, 140NL; Nicolon Corp. Filterweave 70/06; Phillips Fibers Corp. Supac 4Np, 5NP, 7NP; Wellman Quline Inc. Q60, Q80, Q100.

PART 3 EXECUTION

3.1 PREPARATION

A. Compact subgrade to density requirements for subsequent backfill materials.

B. Cut out soft areas of subgrade not capable of compaction in place. Backfill with select structural fill and compact to density equal to or greater than requirements for subsequent fill material.

C. Proof roll subgrade in areas where there will be compacted fill surfaces under concrete tunnel slabs. The subgrade shall be proof rolled by three passes of a 10-ton static smooth wheeled roller or a pneumatic tired power roller under low inflation pressures. Any areas that do not stabilize under proof rolling must be undercut and replaced with well-compacted gravel.

3.2 BACKFILLING

A. Backfill areas to original grades with unfrozen materials.

B. Systematically backfill to allow maximum time for natural settlement. Do not backfill over porous, wet, frozen or spongy subgrade surfaces.

C. Place geotextile fabric over Subsoil Type S1 fill prior to placing next lift of fill.

D. Place fill material in continuous layers and compact in accordance with schedule at end of this section.

E. Employ placement method that does not disturb or damage other work.

F. Maintain optimum moisture content of backfill materials to attain required compaction density.

G. Backfill against supported foundation walls. Do not backfill against unsupported foundation walls.

H. Slope grade away from building minimum 1/4 inch in 10 ft, unless noted otherwise.

I. Make gradual grade changes. Blend slope into level areas.

Return Piping Replacement 312323-3 PGRU, Geneva, NY

J. Remove surplus backfill materials from site.

K. Leave fill material stockpile areas free of excess fill materials.

3.3 TOLERANCES

A. Top Surface of Backfilling Under Paved Parking and Drive Areas, Walkways, Curbs:

Plus or minus 1/2 inch from required elevations.

B. Top Surface of General Backfilling: Plus or minus 1 inch from required elevations.

3.4 FIELD QUALITY CONTROL

A. Perform laboratory material tests in accordance with ASTM D1557.

B. Perform in place compaction tests in accordance with the following:

1. Density Tests: ASTM D1556, ASTM D2167, or ASTM D2922.

2. Moisture Tests: ASTM D3017.

C. When tests indicate Work does not meet specified requirements, remove Work, replace and retest.

D. Proof roll compacted fill surfaces under tunnel base slab.

E. Frequency of Tests:

1. Every 30 linear feet (185 sq. ft.) of tunnel base slab placed.

3.5 PROTECTION OF FINISHED WORK

A. General Conditions - Execution Requirements - Protecting finished work.

B. Regrade and re-compact fills subjected to vehicular traffic.

3.6 SCHEDULE

A. Fill Under Grass Areas:

1. Fill Type S2, to 4 inches below finish grade, compact uniformly to 85 percent of maximum density per ASTM D1557 Modified Proctor Test Method.

B. Fill to Correct Over-excavation:

1. Fill Type A4, flush to required elevation, compact uniformly to 90 percent of maximum density per ASTM D1557 Modified Proctor Test Method.

C. Fill under and around concrete HPS tunnel:

1. Fill Type A4, flush to required elevation, compact uniformly to 95 percent of maximum density per ASTM D1557 Modified Proctor Test Method.

END OF SECTION

Return Piping Replacement 312323-4 PGRU, Geneva, NY