Amend_4_-_Attach_2_-_Replacement_spec_31_00_00_Earthwork_0004.pdf

DIVISION 31 – EARTHWORK

SECTION 31 00 00 – EARTHWORK

Klamath Falls N.F.H. 31 00 00-1 New National Fish Hatchery

PART 1 - GENERAL

1.01 DESCRIPTION OF WORK

A. The work includes excavation, trenching, shoring, filling, backfilling, subgrade preparation, grading, and compaction.

B. The site soils generally consist of a fill (reworked native soil), residual soil and mudstone. The site soils and mudstone contain variable amounts of diatoms and gypsum. The presence of these constituents causes these materials to have unique engineering properties such as low dry unit weight, high moisture content, low strength, and moderate to high compressibility. As such, special measures will need to be taken to reuse site soils for proposed embankments.

C. Soil and aggregate generated as a result of excavation may be re-used on site if the material meets the requirements for Fill or Backfill, including moisture content. On-site soils are fine-grained with high moisture content and will require processing such as aerating and mixing prior to reuse as fill or backfill. If the material does not meet the requirements for Fill or Backfill, and cannot be conditioned or mixed to meet the requirement for Fill or Backfill with reasonable effort and measures as determined by the Engineer and as described in this specification, the material may be stockpiled on site as indicated on the Drawings.

D. Use of on-site material as fill or backfill is subject to approval by the Engineer as described in these specifications. If a sufficient volume of on-site soils suitable for use as fill and backfill is not encountered during excavation and, in the opinion of the Engineer, a sufficient quantity of on-site materials cannot be conditioned or mixed to produce suitable material to accomplish fill and backfill requirements, the Contractor shall use Imported Select Structural Fill to supplement on-site material in the quantity necessary to accomplish fill and backfill requirements.

E. On-site material which cannot be conditioned or mixed to meet the requirement for fill or backfill with reasonable effort and measures as determined by the Engineer and as described in this specification may be stockpiled on site as indicated on the Drawings.

F. Excess soil and aggregate generated as a result of the work may be stockpiled on site as indicated on the Drawings.

1.02 QUALITY ASSURANCE

A. On-Site Testing and Inspection: The Contractor shall provide and pay for on-site testing and inspection services. On-Site testing and inspection services shall be performed by independent, testing laboratory firms which are in conformance with ASTM E-329 and certified by Oregon Department of Transportation (ODOT).

B. All inspection and testing personnel shall be under direct supervision of Professional Engineers registered in the State of Oregon. Technicians performing field sampling and testing for earthwork shall be Certified Embankment and Base Technicians (CEBT) by Oregon Department of Transportation (ODOT).

C. Sampling and testing for compliance with the contract provisions will be in accordance with Section 01 45 00 – Quality Control.

Klamath Falls N.F.H. 31 00 00-2

D. Compaction Control Tests: The Contractor shall provide and pay for laboratory and on-site field compaction control tests in accordance with the applicable provisions of these specifications.

E. The compaction control density shall be the maximum density at optimum moisture content as determined by:

1. ASTM D 698, Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort, for onsite fill, backfill and subgrade.

2. ASTM D 1557, Standard Methods for Moisture-Density Relationships of Soil and Soil Aggregates, Methods B, C or D as applicable, for imported granular fill and aggregate.

F. Field tests to determine in-place compliance with required densities as specified, shall be performed in accordance with ASTM D 1556, D 2167, or D 2922.

G. Shoring shall be provided in accordance with Specification 31 41 00 – Shoring and Underpinning, applicable local, State and Federal safety codes. Design, agency approval, permits, construction, maintenance, and removal of all shoring elements are the sole responsibility of the Contractor

1.03 REFERENCE STANDARDS

A. OSS – Oregon Department of Transportation Standard Specifications for Construction, 2021 Edition.

1.04 SUBMITTALS

A. Submit in accordance with Section 01 33 00 – Submittal Procedures, the following:

B. Provide and administer a Quality Assurance and Quality Control Program, as described in Section 01 45 00 – Quality Control.

C. Names, telephone numbers, and copies of certifications for all firms and personnel performing field testing related to earthwork.

D. Results for in-place moisture and density tests for fill and backfill. Perform not less than one moisture and density test for each 50 cubic yards of fill and backfill placed with at least one test for every 2 vertical feet of fill or backfill placed.

Submit test results in daily, not more than 24 hours following performance of the test. Each test result shall include:

1. Date and time of test;

2. Summary of weather conditions at the time of the test;

3. In place moisture content;

4. In place density;

5. Test elevation and;

6. Diagram indicating approximate location of test.

E. Results for in-place density tests for subgrade and base aggregate for access roads. Perform not less than one density test for each 800 square feet of access

Klamath Falls N.F.H. 31 00 00-3 road subgrade area prepared for placement of base aggregate and one density test for each 800 square feet of base aggregate placed. Submit test results daily, not more than 24 hours following performance of the test. Each test result shall include:

1. Date and time of test;

2. Summary of weather conditions at the time of the test;

3. In place moisture content;

4. In place density;

5. Test elevation and;

6. Diagram indicating approximate location of test

F. Survey data for verification surveys of all pond subgrade areas and Fill and Stockpile Areas. Verification surveys of pond subgrade areas shall include the bottom surface of the pond, and the sloped sides up to the dike elevation.

Verification surveys of Fill and Stockpile Areas shall extend not less than 10 feet in all directions from the toe of the Fill and Stockpile area and shall include spot elevations in a grid pattern, not less than 25 feet apart.

1. Submit verification surveys of all pond subgrade areas to Engineer for review not less than 7 days prior to planned start of sand layer and pond liner material placement.

2. Submit verification surveys of Fill and Stockpile Areas to Engineer for review not less than 7 days prior to planned start of earthwork.

1.05 SITE CONDITIONS

A. Unusual subsurface conditions at the project site have been investigated and documented in the geotechnical report described in the Statement of Work.

Contractor shall be responsible for review of the report.

B. Verify the location of existing utilities at the site, and use an independent private locate company to assist. Those utilities which are to remain shall be protected from damage and remain operational. Damage to utilities which are to remain shall be repaired by the Contractor at its own expense.

PART 2 - PRODUCTS

2.01 FILL AND BACKFILL

A. All material used as fill or backfill should be free of debris, clay balls, roots, organic matter, frozen soil, man-made contaminants, particles with greatest dimension exceeding 4 inches, and other deleterious materials and should meet the appropriate specification provided in the Oregon Standard Specifications for Construction (OSS) (ODOT 2018) Section 00330.12 – Borrow Material, 00330.13

– Selected General Backfill, or 00330.14 – Selected Granular Backfill.

B. Material used for fill and backfill shall be one of the following:

1. On-Site Soils - Material from excavation, trench excavation or other on-site borrow soils generated during construction at the site. On-site soils

Klamath Falls N.F.H. 31 00 00-4 are fine-grained with high moisture content and will require processing such as aerating and mixing prior to reuse as fill or backfill.

2. Imported Select Structural Fill - Imported granular material used as structural fill should be pit or quarry run rock, crushed rock, or crushed gravel and sand and should meet the specifications provided in OSS

00330.14 – Selected Granular Backfill, 00330.15 – Selected Stone Backfill, or 00330.16 – Stone Embankment. The imported granular material should be angular, fairly well graded between coarse and fine material, and have less than 10 percent by dry weight passing the U.S.

Standard No. 200 Sieve.

2.02 AGGREGATE BASE

A. Aggregate base material shall conform to Specification 32 11 23 – Base Aggregates.

2.03 GRAVEL BORROW

A. Gravel Borrow shall meet the requirements of Specification 32 11 23 – Base Aggregates.

2.04 GRAVEL BACKFILL FOR PIPE ZONE BEDDING

A. Gravel backfill for pipe zone bedding shall consist of crushed, processed or naturally occurring granular material. It shall be free from various types of wood waste or other extraneous or objectionable materials. It shall have such characteristics of size and shape that it will compact and shall meet the following specifications for grading and quality:

Sieve Size Percent Passing (by weight) 1-1/2” square 100 1” square 75-100 5/8” square 50-100 U.S. No. 4 20-80 U.S. No. 40 3-24 U.S. No. 200 10.0 Max.

Sand Equivalent 35 min.

2.05 GRAVEL BACKFILL FOR DRAINS

A. Gravel Backfill for Drains shall conform to the following gradation:

1” square 100 3/4” square 80-100 3/8” square 0-40 U.S. No. 4 0-4 U.S. No. 200 0-2

Klamath Falls N.F.H. 31 00 00-5

2.06 PEA GRAVEL

A. Pea gravel material must be non-plastic, rounded to sub-rounded aggregate material. A minimum of 70 percent by weight of the pea gravel must have at least one fractured face. Pea gravel shall conform to the following gradation:

3/8” square 95-100 U.S. No. 4 0-30 U.S. No. 8 0-15 U.S. No. 200 0-2

2.07 RIPRAP

A. Riprap shall meet the requirements of Class 50 loose riprap in accordance with Section 00390.11 of the Oregon Department of Transportation Standard Specifications for Construction, 2021 Edition.

2.08 DRAIN ROCK USED FOR BACK OF WALL SUBSURFACE DRAINAGE

A. Drain rock used for back-of-wall subsurface drainage systems shall be gravel backfill for drains. The rock shall be wrapped in a geotextile fabric that meets the specifications provided in OSS 02320 – Geosynthetics, Table 02320-1 Geotextile Property Values for Drainage Geotextile. The geotextile shall be installed in conformance with the specifications provided in OSS 00350 – Geosynthetic Installation Requirements.

2.09 STABILIZATION MATERIAL

A. Materials used to construct temporary haul roads for construction traffic or for stabilization of the bases of excavations shall include:

B. Material meeting the specifications of OSS 00330.15 – Stone Backfill Material, except recycled glass should not be used.

C. Riprap shall meet the requirements of Class 50 loose riprap in accordance with Section 00390.11 of the Oregon Department of Transportation Standard Specifications for Construction, 2021 Edition.

2.10 TOPSOIL

A. Topsoil shall conform to Specification Section 32 92 19 – Seeding.

2.11 OFF-SITE BORROW SOURCE INSPECTION

A. Off-site borrow source inspection shall be performed by the Contractor to assure that imported materials are natural, native, virgin materials, free of contaminants, including debris or recycled materials, and meet the requirements of the contract documents.

B. Each source of off-site borrow material shall be tested once per year for physical properties.

C. The Engineer maintains the right to reject any materials that have been determined to be substandard for any reason. In the event of rejection, it shall be

Klamath Falls N.F.H. 31 00 00-6 the responsibility of the contractor to remove all stockpiles of rejected material from the site.

D. General: Materials shall of the quality, size, shape, gradation, or equal to that manufacture as specified herein. The Contractor shall submit a characterization report of any and all imported material prior to any on-site placement. The characterization report will include source identification and analyses of a material source sample. The material shall not be imported to the site until approved by the Engineer. Once approved and imported to the site, the Contractor shall perform an on-site inspection of the material to verify that it is the material described in the characterization report.

E. Source Identification: The Contractor shall provide documentation of the origin of imported materials and maps identifying specific location(s) of material source(s).

F. Inspection of Source: The Contractor shall inspect all material sources. During such inspection, the Contractor shall assure that materials to be delivered to the jobsite are likely to meet the appropriate specifications. The Contractor shall provide the Engineer two weeks notice of such inspections. The Engineer or a designated representative may accompany the Contractor to witness such inspections. This witnessing shall in no way release the Contractor from complying with the specifications and in no way shall be construed as approval of any particular source of material.

G. Inspection of Materials at the Jobsite: The Contractor shall visually inspect import material upon delivery. Materials shall be inspected for presence of foreign, recycled, or reprocessed material. The Engineer may at any and all times perform an independent inspection. Material may be rejected due to the presence of deleterious substances or as a result of substandard test results.

2.12 GEOTEXTILE SEPARATION FABRIC

A. Geotextile separation fabric shall meet the specifications provided in OSS

02320.20 – Geotextile Property Values, Table 02320-4 Geotextile Property Values for Subgrade Geotextile (Separation). If riprap is used for Stabilization Material, the geotextile should meet the specifications provided in OSS 02320.20

– Geotextile Property Values, Table 02320-2 Geotextile Property Values for Riprap Geotextile.

2.13 GABION WALL

A. Gabion wall baskets shall be welded wire baskets conforming to the specifications provided in OSS 02340 – Rock Gabion Baskets.

B. Gabion baskets shall be filled with 4 inch to 8 inch rock material meeting the specifications of OSS 00390.11(b) – Riprap Requirements.

PART 3 - EXECUTION

3.01 GENERAL

A. Excavating, filling and grading shall be completed within the tolerances established or within reasonably close conformity with the alignment grade and cross sections indicated on the Drawings or as established within these specifications.

Klamath Falls N.F.H. 31 00 00-7

B. Existing site soils consists primarily of fine-grained silt and clay overlying mudstone. Earthwork shall be completed in a manner that reduces disturbance to exposed subgrades.

C. The site soils are easily disturbed due to their high moisture content. If not carefully executed, site preparation, utility trench work, and roadway excavation can create extensive soft areas that will require repair at the Contractor’s expense. Earthwork planning shall include considerations for minimizing subgrade disturbance, such as using track-mounted excavation equipment, and loading removed material into trucks supported on granular haul roads.

3.02 EXCAVATION

A. Excavation: Shall be the naturally occurring and previously placed fill including earth, sand, gravel, clays, or mixtures of the above, required to be moved for the construction of ponds, access roads, water control piping and vaults, buildings and associated work.

B. Excavation material shall be moved with the use of mechanical equipment, such as shovels, loaders, bulldozers, graders, rippers, etc., but shall not require drilling and blasting or drilling and line breaking.

C. Excavation by sluicing method will not be permitted.

D. In general, excavation shall be removed in horizontal layers in such a way that the resulting material will be a reasonable blend of the naturally occurring materials.

E. Protect excavated material, stockpiled for reuse as fill or backfill, from contamination by other materials and from precipitation by covering with waterproof sheeting and other effective means.

F. Stockpiles shall be employed for excavated material to be reused as fill or backfill. At end of project, material remaining in stockpile for reuse shall be considered surplus material. Surplus material shall be placed in the Fill and Stockpile Areas indicated on the Drawings.

G. Following completion of all earthwork and prior to substantial completion, Contractor shall perform a topographic survey of Fill and Stockpile areas to document the area and volume of the Fill and Stockpile area. Topographic survey of Fill and Stockpile areas shall extend not less than 10 feet in all directions from the toe of the Fill and Stockpile area. Submit topographic survey data as indicated in this Specification.

H. Unsuitable Subgrade Excavation: Shall consist of materials excavated below the design subgrade surface as directed by the Engineer including unstable materials such as soft soil, peat, muck, water impregnated clays, swampy or other undesirable materials, including buried logs, stumps, or trash. Unsuitable Subgrade Excavation materials shall be removed to the depth designated by the Engineer.

Unsuitable Subgrade Excavation material shall be replaced with Gravel Backfill for Drains per paragraph 2.05, Aggregate Base per paragraph 2.02, or Stabilization Material per paragraph 2.09 as directed by the Engineer. The replacement material shall be underlain by a geotextile fabric that meets the specifications provided in OSS 02320 – Geosynthetics, Table 02320-4 Geotextile

Klamath Falls N.F.H. 31 00 00-8

Property Values for Subgrade Geotextile (Separation). The geotextile shall be installed in conformance with the specifications provided in OSS 00350 – Geosynthetic Installation Requirements.

Unsuitable Subgrade Excavation materials shall be transported off-site by the Contractor and disposed of in accordance with all applicable regulatory requirements at a disposal facility that is appropriate for the material being disposed.

3.03 TEMPORARY OPEN CUTS

A. Temporary soil cuts for site excavations that are more than 4 feet deep should be adequately sloped back to prevent sloughing and collapse, in accordance with Occupational Safety and Health Administration (OSHA) guidelines.

B. The stability and safety of cut slopes depend on multiple number of factors, including:

1. Type and density of the soil

2. Presence and amount of groundwater seepage

3. Depth of cut

4. Proximity and magnitude of the cut to any surcharge loads, such as soil stockpiles, stored materials, equipment, traffic loads, or structures

5. Duration of the open excavation

6. Care and methods used by the Contractor

C. The Contractor shall ensure that the excavation is properly sloped or braced for worker protection, in accordance with OSHA guidelines. Most of the site soils to be excavated are weak, fine-grained soils that are classified as OSHA Class C for excavation purposes. If site constraints do not allow proper excavation slopes for trenching, shoring may be used to support trench excavations. Shoring selection and design should be the responsibility of the Contractor.

3.04 SUBGRADE PREPARATION AND EVALUATION

A. Initial site preparation and earthwork operations shall include clearing and grubbing, stripping, and grading to establish subgrade elevation for improvements. The surficial topsoil and organic soils shall to be removed from within the footprint of buildings, ponds, and areas of new fill. Contractor shall assume that the depth of organic material to be stripped is typically less than 6 inches. Actual stripping depths shall be based on field observations at the time of construction. Stripped material shall be transported off site for disposal.

B. Following stripping and prior to the placement of fill, the suitability of the subgrade shall be evaluated by proof rolling with a fully loaded dump truck or similar heavy rubber-tired construction equipment to identify soft, loose, or unsuitable areas. Contractor shall provide equipment acceptable to the Engineer for proof roll and proof roll shall be observed by the Engineer who will evaluate the suitability of the subgrade and identify areas of yielding that are indicative of soft or loose soil. Contractor shall provide not less than 48 hours notice to the Engineer prior to proof rolling of each area.

Klamath Falls N.F.H. 31 00 00-9

C. Subgrade areas for shallow footings and water control structures, vaults, catch basins and manholes shall be evaluated by the Engineer by probing with a steel foundation probe. Contractor hall provide not less than 48 hours notice to the Engineer requesting the subgrade evaluations

3.05 GEOTEXTILE SEPARATION FABRIC

A. Construct geotextile separation fabric at the locations indicated on the Drawings and in conformance with specifications provided in OSS 00350 – Geosynthetic Installation.

3.06 CONTRACTOR HAUL ROADS AND STAGING AREAS

A. The use of granular haul roads and staging areas will be likely necessary for support of repeated construction traffic in order to reduce subgrade disturbance.

The extent of staging and haul road areas as well as the required thickness of granular material will vary with the Contractor’s sequencing of a project and type/frequency of construction equipment.

B. Base aggregate indicated on the Drawings for access roads is not sufficient for support of construction traffic. If proposed Contractor haul roads are proposed through or along areas to be surfaced for access roads as indicated on the plans, access road base aggregate shall be placed over the top of stabilization materials used for construction of Contractor haul roads.

C. Contractor haul roads and staging areas shall be constructed using Stabilization Material placed to a depth of not less than 12 inches, actual thickness required will be dependent on Contractor’s means and methods.

D. A geotextile should be placed as a barrier between the native soil subgrade and the Stabilization Material. The Stabilization Material should be placed in conformance with the specifications provided in OSS 00331 – Subgrade Stabilization. The geotextile should meet the specifications provided in OSS

02320.20 – Geotextile Property Values, Table 02320-4 Geotextile Property Values for Subgrade Geotextile (Separation). If riprap is used for Stabilization Material, the geotextile should meet the specifications provided in OSS 02320.20

– Geotextile Property Values, Table 02320-2 Geotextile Property Values for Riprap Geotextile. The geotextile should be installed in conformance with the specifications provided in OSS 00350 – Geosynthetic Installation.

E. Stabilization material shall be placed in lifts between 12 and 18 inches thick and be compacted to a well-keyed condition with appropriate compaction equipment without using vibratory action.

3.07 EXCAVATION FOR STRUCTURES AND UTILITIES

A. Excavate as necessary for structure and utilities to the lines and grades indicated on the drawings.

B. Excavation below the designed depth, except as directed by the Owner, shall be backfilled with aggregate base, gravel backfill for drains, or other suitable backfill material as approved by the Engineer and compacted as specified, at no extra cost to the Owner.

C. Brace and shore sides of excavations. Comply with all federal, state, and local regulations regarding shoring, bracing, and other protection requirements.

Klamath Falls N.F.H. 31 00 00-10

D. Keep water out of excavated pits and trenches by pumping or other means of dewatering. Water level shall be kept below the bottom of concrete pours before, during, and for a minimum of three days thereafter.

E. Protect excavated material, stockpiled for use as fill or backfill, from contamination by other materials and from damage by weather by covering with waterproof sheeting or other suitable means.

3.08 FILL AND EMBANKMENT

A. Fill and embankment shall only be placed over a prepared subgrade that consists of firm, inorganic on-site soils or structural fill.

B. Fill and embankment shall be placed and compacted in accordance with OSS

00330.43 – Earthwork Compaction, except as noted in this Specification.

C. On-site soils should be compacted using quad-drummed/-wheeled sheepsfoot-/padfoot-style rollers. Where use of quad-drummed rollers is not feasible due to space constraints, single-drummed sheepsfoot-/padfoot-style rollers may be used provided that the rubber-tired rear wheels are not inducing excessive deflection or pumping of the subgrade. Due to the high moisture content and fine-grained nature of the site soils, vibratory rollers shall not be used for compaction of the on-site soils.

D. Place fill or backfill in uniform horizontal lifts with a thickness appropriate for the material type and compaction equipment. Table 31 00 00 - 3.08.1 provides requirements for uncompacted lift thicknesses.

Table 31 00 00 - 3.08.1 – Maximum Lift Thickness, Fill and Embankment

Compaction Equipment

Maximum Uncompacted Lift Thickness (inches)

On-Site Soils

Granular and Crushed Rock, Max. Particle Size

1.5 Inch

Crushed Rock, Max. Particle Size Greater Than 1.5 Inch

Plate Compactors and Jumping Jacks

8 8 Not Permitted

Rubber-Tire Equipment 8 12 8

Light Roller 10 12 10

Heavy Roller 12 18 16

Hoe Pack Equipment (trenches or Structure backfill only)

16 24 16

E. Construct earth embankment in compacted layers of uniform thickness. Carry the layers up full width from the bottom of the embankment. Compact the slopes

Klamath Falls N.F.H. 31 00 00-11 of all embankments to the required density as part of the embankment compaction work. For slopes greater than 8 feet tall, the faces of the slope should be overbuilt by at least 6 inches and then trimmed back to the required grade to ensure appropriate compaction at the finished grade.

F. Do not place fill and backfill until the required tests and evaluation of the underlying materials have been performed and the appropriate approvals have been obtained.

G. Limit the maximum particle size within the fill to two-thirds of the loose lift thickness.

H. Control the moisture content of fill and backfill materials to within the specified percentage of the optimum moisture content based on laboratory Proctor tests.

1. Imported select structural fill: within 3 percent

2. On-site soils with optimum moisture content above 40 percent: within 5 percent

3. On-site soils with optimum moisture contents above 80 percent: within 10 percent

I. For on-site soils with optimum moisture contents above 40 percent, control the moisture content of the fill to within 5 percent of the optimum. For on-site soils with optimum moisture contents above 80 percent, control the moisture content of the fill to within 10 percent of the optimum. The optimum moisture content corresponds to the maximum attainable Proctor dry density.

J. Perform in-place moisture and density tests on fill and backfill in the field to verify moisture control and compaction. Perform not less than one moisture and density test for each 50 cubic yards of fill and backfill placed, with at least one test for every 2 vertical feet of fill or backfill placed. Submit test results in accordance with these Specifications.

K. Compact fill soils to the percentages of maximum dry density as shown in Table 31 00 00 - 3.08.2.

Table 31 00 00 - 3.08.2 – Fill and Backfill Compaction

Fill Material

Percent of Maximum Dry Density Determined in Accordance with ASTM D698 and ASTM D1557 as indicated in Paragraph 1.02

0 To 2 Feet Below Subgrade

>2 Feet Below Subgrade

Fill – On-Site Material 92 90

Fill – Import 95 90

Aggregate Base 95 95

Trench Backfill 95 92

Nonstructural Trench Backfill 88 88

Klamath Falls N.F.H. 31 00 00-12

Nonstructural Zones 88 88

L. Place material used for the construction of fill or embankment in horizontal layers upon earth which has been prepared in accordance with these Specifications or otherwise approved by the Engineer for embankment construction.

M. The right is reserved for the Engineer to order the use of any particular compacting unit discontinued if it is not capable of compacting the material to the required density within a reasonable time, or if the equipment may damage underlying or adjacent soils or structures.

3.09 TALL EMBANKMENT CONSTRUCTION

A. For construction embankments with over 10 feet of fill thickness, the fill shall be constructed in stages. Once the fill has reached the 10-foot thickness, it shall be allowed to rest through a Wait Period to allow dissipation of excess pore pressures. Contractor shall assume that each the Wait Period for an embankment depth of 10 feet will be 4 weeks, though actual Wait Period duration will depend upon pore pressure and settlement monitoring results.

B. For each tall embankment work area, Contractor shall install vibrating wire piezometers with data loggers to monitor pore pressure dissipation. A minimum of four vibrating wire piezometers shall be installed at depths of 10, 5, and 0 feet below native grade and 5 feet above native grade. The three vibrating wire piezometers installed at or below existing grade shall be installed prior to placement of embankment materials. The fourth vibrating wire piezometer installed at 5 feet above existing grade (e.g. within the embankment) shall be installed prior to placement of additional embankment materials above that elevation. The vibrating wire piezometers shall be protected from damage during earthwork activities. Monitoring shall continue until it is demonstrated the excess pore pressures have dissipated.

C. If construction sequencing allows the initial embankment depth of 10 feet to rest for at least 8 weeks, then no pore pressure monitoring is will be required.

D. Subsequent to the placement and Wait Period for the initial 10 feet depth of embankment, additional fill may be placed in 5-foot- thick stages with associated Wait Periods between each stage.

E. In addition to pore pressure monitoring, the Contractor shall perform settlement monitoring to measure potential slope movement and ground settlement.

Settlement monitoring shall include the following:

F. At least one settlement plate and rod shall be installed on the native subgrade near the point of thickest fill prior to the placement of fill. Additional plates may be required depending upon the variation of thickness of fill.

G. Once the embankment has reached a depth that requires a Wait Period (after initial 10 feet and after subsequent 5-foot layers), at least two surface settlement monitoring points shall be installed on the ground surface at the top of the each stage of fill.

Klamath Falls N.F.H. 31 00 00-13

H. The settlement plate(s) and adjacent ground, and surface monitoring points, shall be surveyed at the following intervals:

1. Immediately upon installation

2. Daily during all earthwork activities

3. Daily for the first week of the Wait Period

4. Three times weekly for the second and third weeks of the Wait Period

5. Once weekly after the first three weeks of the Wait Period

I. Survey equipment used for settlement monitoring shall have an accuracy of at least 1/100th of a foot and be referenced to a stationary datum at least 100 feet from the edge of active work areas.

J. Settlement monitoring data shall be provided to the Engineer each day collected, and the monitoring shall continue until the data show that settlement is substantially completed, as determined by the Engineer.

3.10 FILL, BACKFILL AND COMPACTION FOR STRUCTURES AND UTILITIES

A. Excavations for all underground structures including manholes, catch basins, flow splitters, vaults, handholes and/or other structures, shall be over excavated by two feet. The subgrade shall be prepared, and a minimum of 24 inches of Aggregate Base or Gravel Backfill for Drains, or more if specified on the Drawings shall be placed and compacted. If subgrade is soft and cannot be adequately compacted, contact Engineer for direction.

B. Place backfill and structural backfill to lines and grades indicated on the Drawings.

C. Remove water from excavated areas, by pumping or other means, before placing any fill material.

D. Prepare subgrade, as specified in paragraph 3.04, before placing any fill or backfill material.

E. Do not place any fill against concrete walls/structures until the concrete has attained its specified design strength and/or certain other construction sequence criteria, if noted on the drawings, are met, or as specifically approved by the Engineer.

F. Pipe zone bedding material shall provide uniform support along the entire pipe barrel, without load concentration at joint collars or bells. All adjustments to line and grade shall be made by scraping away or filling in with bedding material under the body of the pipe and not by blocking or wedging. Bedding disturbed by pipe movement, or by removal of shoring movement of a trench shield or box, shall be reconsolidated prior to backfill. Pipe zone bedding shall be placed in loose layers and compacted to 90 percent maximum density. Bedding shall be placed, spread, and compacted before the pipe is installed so that the pipe is uniformly supported along the barrel. Lifts of not more than 6 inches in thickness shall be placed and compacted along the sides of the pipe to the height shown in the Drawings. Material shall be worked carefully under the pipe haunches and then compacted. If the Engineer determines that the material existing in the

Klamath Falls N.F.H. 31 00 00-14 bottom of the trench is satisfactory for bedding the pipe, the existing material shall be loosened, regraded, and compacted to form a dense, unyielding base.

G. Backfill trenches and structure excavations by placing and compacting material in horizontal layers as specified in paragraph 3.08.

3.11 BENCHING FOR FILL ON SLOPES

A. In locations where fills are to be placed on slopes steeper than 5H:1V (20 percent gradient), level benches shall be cut into the existing sloping surfaces.

B. Each bench shall be at least 5 feet wide and no more than 5 feet tall. The benches shall be level or have an outward gradient of 0.5 percent or less. The lowest bench, also known as the keyway, shall be a minimum of 8 feet wide or one and one-half times the width of the compaction equipment, whichever is wider. The keyway shall slope back into the hillside at a 1 percent gradient.

C. If identified by the Engineer as being required, a gravel subdrain shall be constructed at the back of the keyway. The subdrain shall consist of a minimum of a 3-foot-wide by 3-foot-tall “wedge” of drain rock placed at the back of the keyway. The drain rock shall be completely wrapped with a geotextile drainage fabric. A perforated pipe shall be installed at the base of the gravel to collect water seepage. The collector pipe shall “daylight” at an appropriate location near the base of the slope.

3.12 GABION WALL

A. Construct gabion walls in accordance with the requirements of OSS 00396B – Prefabricated modular retaining walls and OSS 02340 – Rock Gabion Baskets.

3.13 COMPACTION

A. Compaction shall be performed with approved compaction equipment suited to the soil and the area being compacted and as noted in paragraph 3.07. Moisten or aerate material as necessary to provide the moisture content that will readily facilitate obtaining the specified compaction with the equipment used. Each lift of material placed shall be uniformly compacted to the density indicated for the specific material and use set forth in paragraph 3.08. The percent of density required is in relation to the maximum density obtainable at optimum moisture content (Compaction Control Density) as determined in paragraphs 1.02 and 3.08.

3.14 COMPACTION CONTROL TESTS

A. Laboratory and field tests shall be performed in accordance with the applicable provisions of these Specifications.

B. Compaction control density shall be the maximum density at optimum moisture content as determined by ASTM D 1557 or ASTM D698 as specified in paragraph 1.02 as applicable but shall be no less than the dry densities indicated in Table 31 00 00 - 3.08.2.

C. Field tests to determine in place compliance with required densities as specified, shall be performed in accordance with ASTM D1556, D2167, or D2922.

3.15 PREPARATION FOR BASE AGGREGATE SURFACING OF ACCESS ROADS

Klamath Falls N.F.H. 31 00 00-15

A. Preparation of Subgrade: Immediately prior to placement of surfacing materials, clean the entire width of the area of all debris. All depressions or ruts which contain storm water shall be drained.

B. Shape the entire subgrade to a smooth uniform surface, true to line, grade, and cross section. Compact the subgrade material to a depth of at least 8 inches to at least 95% of the maximum density as determined by compaction tests ASTM Designation D1557. If soft or spongy material underlying the upper eight inches of the area being prepared precludes satisfactory compaction of the upper eight inches, loosen, aerate, or excavate, replace and compact to the required density as directed by the Engineer.

C. Remove and dispose of excess material which cannot be disposed of by normal drifting to low spots during blading and shaping operations or by placing in subgrade areas deficient in materials or by wasting. Subgrade areas deficient in materials shall be brought to grade by importing suitable materials from other subgrade areas or other sources as directed by the Engineer. Materials added to subgrade areas deficient in materials shall be watered and compacted as necessary to yield a true finished subgrade as described above.

D. Once it is prepared, maintain the subgrade for surfacing in the finished condition until the first course of surfacing has been placed.

E. Subgrade Protection: Take all precautions necessary to protect the subgrade from damage; hauling over the finished subgrade shall be limited to that which is essential for construction purposes. Areas that require repetitive hauling shall have stabilization haul roads constructed over the subgrade.

F. Equipment used for hauling over the prepared subgrade which, in the opinion of the Engineer, is causing undue damage to the prepared subgrade or to the underlying materials, shall be removed from the work at the request of the Engineer.

G. Repair at the Contractor's expense all cuts, ruts and breaks in the surface of the subgrade prior to placing surfacing, treated base, or paving materials.

H. Protect the prepared subgrade from both the Contractor's traffic and public traffic and maintain the subgrade by blading and rolling as frequently as may be necessary to preserve the subgrade in a completely satisfactory condition.

END OF SECTION