S01. Atch 4. Specifications - Erickson WRE.pdf

USDA

NATURAL RESOURCES CONSERVATION SERVICE

DESIGN PACKAGE

Prepared For: Erickson

Project: Wetland Restoration

Easement # 5463221901QRK

NRCS Field Office: Roseau Minnesota

Conservation Practices: Dike (356)

Job Class II

Date: March 2020

NRCS-Minnesota (210-VI-NEH, May 2005) MN2-1

Minnesota Construction Specification 2—Clearing and Grubbing

1. Scope The work consists of clearing and grubbing and disposal of trees, snags, logs, brush, stumps, shrubs, and rubbish from the designated areas.

2. Protection of existing vegetation Trees and other vegetation designated to remain undisturbed shall be protected from damage throughout the duration of the construction period. Any damages resulting from the contractor's operations or neglect shall be repaired by the contractor.

Earthfill, stockpiling of materials, vehicular parking, and excessive foot or vehicular traffic shall not be allowed within the drip line of vegetation designated to remain in place. Vegetation damaged by any of these or similar actions shall be replaced with viable vegetation of the same species, similar condition, and like size unless otherwise approved by the engineer.

Any cuts, skins, scrapes, or bruises to the bark of the vegetation shall be carefully trimmed and local nursery accepted procedures used to seal damaged bark.

Any limbs or branches 0.5 inch or larger in diameter that are broken, severed, or otherwise seriously damaged during construction shall be cut off at the base of the damaged limb or branch flush with the adjacent limb or tree trunk. All roots 1-inch or larger in diameter that are cut, broken, or otherwise severed during construction operations shall have the end smoothly cut perpendicular to the root.

Roots exposed during excavation or other operations shall be covered with moist earth or backfilled as soon as possible to prevent the roots from drying out.

3. Marking The limits of the area(s) to be cleared and grubbed will be marked by stakes, flags, tree markings, or other suitable methods. Trees to be left standing and uninjured will be designated by special markings placed on the trunk about 6 feet above the ground surface.

4. Clearing and grubbing All trees not marked for preservation and all snags, logs, brush, stumps, shrubs, rubbish, and similar materials shall be cleared from within the limits of the designated areas. Unless otherwise specified, all stumps, roots, and root clusters that have a diameter of 1 inch or larger shall be grubbed out to a depth of at least 2 feet below subgrade for concrete structures and 1 foot below the ground surface at embankment sites and other designated areas.

5. Disposal All materials cleared and grubbed from the designated areas shall be disposed of at locations shown on the drawings or in a manner specified in section 6. The contractor is responsible for complying with all local rules and regulations and the payment of any and all fees that may result from disposal at locations away from the project site.

6. Measurement and Payment

Method—For items of work for which specific lump sum prices are established in the contract, payment for clearing and grubbing is made at the contract lump sum price. Such payment shall constitute full compensation for all labor, equipment, tools, and all other items necessary and incidental to the completion of the work.

NRCS-Minnesota (210-VI-NEH, May 2005) MN2-2

7. Items of work and construction details

Clearing and grubbing shall removal all woody debris from the existing berm area prior to topsoil removal.

All debris shall be disposed of off site or burned with ashes spread in such a manner as to not kill vegetation.

The debris may not be buried on easement site.

Payment method shall be lump sum.

(210-VI-NEH, May 2001)

Construction Specification 8—Mobilization and Demobilization

The work consists of the mobilization and demobilization of the contractor's forces and equipment necessary for performing the work required under the contract. It does not include mobilization and demobilization for specific items of work for which payment is provided elsewhere in the contract. Mobilization will not be considered as work in fulfilling the contract requirements for commencement of work.

2. Equipment and material Mobilization shall include all activities and associated costs for transportation of contractor's personnel, equipment, and operating supplies to the site; establishment of offices, buildings, and other necessary general facilities for the contractor's operations at the site; premiums paid for performance and payment bonds including coinsurance and reinsurance agreements as applicable;

and other items specified in section 4 of this specification.

Demobilization shall include all activities and costs for transportation of personnel, equipment, and supplies not required or included in the contract from the site; including the disassembly, removal, and site cleanup of offices, buildings, and other facilities assembled on the site specifically for this contract.

This work includes mobilization and demobilization required by the contract at the time of award.

If additional mobilization and demobilization activities and costs are required during the performance of the contract as a result of changed, deleted, or added items of work for which the contractor is entitled to an adjustment in contract price, compensation for such costs will be included in the price adjustment for the item or items of work changed or added.

3. Payment Payment will be made as the work proceeds, after presentation of paid invoices or documentation of direct costs by the contractor showing specific mobilization and demobilization costs and supporting evidence of the charges of suppliers, subcontractors, and others. When the total of such payments is less than the lump sum contract price, the balance remaining will be included in the final contract payment. Payment of the lump sum contract price for mobilization and demobilization will constitute full compensation for completion of the work.

Payment will not be made under this item for the purchase costs of materials having a residual value, the purchase costs of materials to be incorporated in the project, or the purchase costs of operating supplies.

4. Items of work and construction details

Mobilization/Demobilization is a single lump sum bid item. The contractor and NRCS representative will identify an onsite staging area prior to mobilization.

NRCS-Minnesota (210-VI-NEH, May 2005) MN5-1

Minnesota Construction Specification 5—Pollution Control

The work consists of installing measures or performing work to control erosion and minimize the production of sediment and other pollutants to water and air from construction activities.

2. Material specification All material furnished shall meet the requirements of the material specifications listed in section 7 of this specification.

3. Erosion and sediment control measures and works The measures and works shall include, but are not limited to, the following:

Staging of earthwork activities—The excavation and moving of soil materials shall be scheduled to minimize the size of areas disturbed and unprotected from erosion for the shortest reasonable time.

Seeding—Seeding to protect disturbed areas shall occur as soon as reasonably possible following completion of that earthwork activity.

Mulching—Mulching to provide temporary protection of the soil surface from erosion.

Diversions—Diversions to divert water from work areas and to collect water from work areas for treatment and safe disposition. They are temporary and shall be removed and the area restored to its near original condition when the diversions are no longer required or when permanent measures are installed.

Stream crossings—Culverts or bridges where equipment must cross streams. They are temporary and shall be removed and the area restored to its near original condition when the crossings are no longer required or when permanent measures are installed.

Sediment basins—Sediment basins collect, settle, and eliminate sediment from eroding areas from impacting properties and streams below the construction site(s). These basins are temporary and shall be removed and the area restored to its original condition when they are no longer required or when permanent measures are installed.

Sediment filters—Straw bale filters or geotextile sediment fences trap sediment from areas of limited runoff. Sediment filters shall be properly anchored to prevent erosion under or around them. These filters are temporary and shall be removed and the area restored to its original condition when they are no longer required or when permanent measures are installed.

Waterways—Waterways for the safe disposal of runoff from fields, diversions, and other structures or measures. These works are temporary and shall be removed and the area restored to its original condition when they are no longer required or when permanent measures are installed.

Other—Additional protection measures as specified in section 7 of this specification or required by Federal, State, or local government.

4. Chemical pollution

NRCS-Minnesota (210-VI-NEH, May 2005) MN5-2

The contractor shall provide watertight tanks or barrels or construct a sump sealed with plastic sheets to dispose of chemical pollutants, such as drained lubricating or transmission fluids, grease, soaps, concrete mixer washwater, or asphalt, produced as a by-product of the construction activities. At the completion of the construction work, sumps shall be removed and the area restored to its original condition as specified in section 7 of this specification. Sump removal shall be conducted without causing pollution.

Sanitary facilities, such as chemical toilets, or septic tanks shall not be located next to live streams, wells, or springs. They shall be located at a distance sufficient to prevent contamination of any water source. At the completion of construction activities, facilities shall be disposed of without causing pollution as specified in section 7 of this specification.

5. Air pollution The burning of brush or slash and the disposal of other materials shall adhere to state and local regulations.

Fire prevention measures shall be taken to prevent the start or spreading of wildfires that may result from project activities. Firebreaks or guards shall be constructed and maintained at locations shown on the drawings.

All public access or haul roads used by the contractor during construction of the project shall be sprinkled or otherwise treated to fully suppress dust. All dust control methods shall ensure safe construction operations at all times. If chemical dust suppressants are applied, the material shall be a commercially available product specifically designed for dust suppression and the application shall follow manufacturer's requirements and recommendations. A copy of the product data sheet and manufacturer's recommended application procedures shall be provided to the engineer 5 working days before the first application.

6. Maintenance, removal, and restoration All pollution control measures and temporary works shall be adequately maintained in a functional condition for the duration of the construction period. All temporary measures shall be removed, and the site restored to near original condition.

7. Measurement and Payment Method—For items of work for which lump sum prices are established in the contract, payment is made as the work proceeds and supported by invoices presented by the contractor that reflect actual costs. If the total of all progress payments is less than the lump sum contract prices for this item, the balance remaining for this item will be included in the final contract payment. Payment of the lump sum contract price will constitute full compensation for completion of the work.

8. Construction details The erosion prevention and sediment control BMPs below must be followed at all construction sites where one or more acres of land is disturbed, unless additional or alternative storm-water control practices are specifically required in a permit issued for the construction activity.

The contractor is responsible for the pollution control and the plan to control must get approval of the inspector prior to final approval. Additional erosion control may be required, depending on weather conditions, time of year and contractor construction methods

a. Minimize size of disturbed area – When permanent vegetation must be disturbed, limit the area of disturbance to the minimum required for the project.

NRCS-Minnesota (210-VI-NEH, May 2005) MN5-3

b. Sediment controls – Where disturbed areas have steep slopes or concentrated flow, use a combination of buffers and/or other sediment control measures (e.g., silt fences or properly keyed and staked hay bales) as necessary to protect water quality. All sediment control practices must be established on down gradient perimeters before beginning construction activities that disturb the soil. These practices shall remain in place until final stabilization has been established.

c. Soil stockpiles – Place topsoil or other temporary stockpiles of soil in locations where they will not be subject to erosion from channelized flow (e.g., avoid grassed waterways, tile inlets, gullies, road ditches, drainage ditches, intermittent streams or other water conveyance systems). If stockpiles are placed within 300 feet and up-slope of a water of the state or tile inlet, maintain a minimum 50-foot-wide grass buffer or use equivalent sediment control measures between the stockpile and resource of concern (e.g., silt fences or properly keyed and staked hay bales).

d. Immediately seed and temporarily stabilize disturbed areas – Seed and temporarily stabilize disturbed areas with mulch or blanket until the seed establishes a permanent vegetative cover. Temporary stabilization (e.g., mulch or blanket) must be done within the following timeframes after final grading:

• Slopes 3:1 or steeper – 1 days

• Slopes 10:1 to 3:1 – 3 days

• Slopes 10:1 or flatter – 7 days

e. Control sediment losses over the winter/spring months – If construction is completed after the fall seeding cutoff date, use any combination of the following practices that are necessary to avoid erosion, control sediment, and protect water quality from snow melts and spring rains.

• Grade along the contour. The tracks should be horizontal to the slope. Track the finished grade to compact the soil surface for temporary erosion protection.

• Apply mulch for erosion and frost protection (e.g., straight disk, tacking tool, tackifier added to hydro-mulch).

• Apply temporary seeding/ winter wheat seeding

• Apply mulch, blanket and dormant seeding.

• Install silt fence or stake hay bales downslope of disturbed area.

• Implement seeding and final stabilization as soon as feasible the following spring.

f. Project Erosion Control – The contractor shall ensure that no soil leaves the property due to erosion. Construction staging and stockpiling shall be conducted so that any rainfall does not erode soil into waterways. The methods used to prevent erosion is the contractor’s responsibility.

NRCS-Minnesota (210-VI-NEH, May 2005) MN6-1

Minnesota Construction Specification 6—Seeding, Sprigging, and Mulching

1. Scope The work consists of preparing the area for treatment; furnishing and placing seed, sprigs, mulch, inoculants, lime, and other soil amendments; and anchoring mulch in designated areas as specified.

2. Material Seed—All seed shall conform to the current rules and regulations of the state where it is being used and shall be from the latest crop available. It shall meet or exceed the standard for purity and germination listed in section 6.

Seed shall be labeled in accordance with the state laws and the U.S. Department of Agriculture rules and regulations under the Federal Seed Act in effect on the date of invitations for bids. Bag tag figures are evidence of purity and germination. No seed will be accepted with a test date of more than 9 months before the delivery date to the site.

Seed that has become wet, moldy, or otherwise damaged in transit or storage will not be accepted.

The percent of noxious weed seed allowable shall be as defined in the current State laws relating to agricultural seeds. Each type of seed shall be delivered in separate sealed containers and fully tagged unless exception is granted in writing by the engineer.

Inoculants—The inoculant for treating legume seeds shall be a pure culture of nitrogen-fixing bacteria prepared specifically for the species and shall not be used later than the date indicated on the container or as otherwise specified. A mixing medium, as recommended by the manufacturer, shall be used to bond the inoculant to the seed. Two times the amount of the inoculant recommended by the manufacturer shall be used except four times the amount shall be used when seed is applied using a hydraulic seeder. Seed shall be sown within 24 hours of treatment and shall not remain in the hydraulic seeder longer than 4 hours.

Mulch tackifiers—Asphalt emulsion tackifiers shall conform to the requirements of ASTM D 977, Specification for Emulsified Asphalt. The emulsified asphalt may be rapid setting, medium setting, or slow setting. Nonasphaltic tackifiers required because of environmental considerations shall be as specified in section 6.

Straw mulch material—Straw mulch shall consist of wheat, barley, oat or rye straw, hay, grass cut from native grasses, or other plants as specified in section 6. The mulch material shall be air-dry, reasonably light in color, and shall not be musty, moldy, caked, or otherwise of low quality. The use of mulch that contains noxious weeds is not permitted. The contractor shall provide a method satisfactory to the engineer for determining weight of mulch furnished.

Other mulch materials—Mulching materials, such as wood cellulose fiber mulch, mulch tackifiers, synthetic fiber mulch, netting, and mesh, are other mulching materials that may be required for specialized locations and conditions. These materials, when specified, must be accompanied by the manufacturer's recommendations for methods of application.

3. Seeding mixtures, sod, sprigs, and dates of planting The application rate per acre for seed mixtures, sprigs, or sod and date of seeding or planting shall be as shown on the plans or as specified in section 6.

4. Seedbed preparation and treatment

NRCS-Minnesota (210-VI-NEH, May 2005) MN6-2

Areas to be treated shall be dressed to a smooth, firm surface. On sites where equipment can operate on slopes safely, the seedbed shall be adequately loosened (4 to 6 inches deep) and smoothed. Depending on soil and moisture conditions, disking or cultipacking, or both, may be necessary to properly prepare a seedbed. Where equipment cannot operate safely, the seedbed shall be prepared by hand methods by scarifying to provide a roughened soil surface so that broadcast seed will remain in place.

If seeding is to be accomplished immediately following construction operations, seedbed preparation may not be required except on a compacted, polished, or freshly cut soil surface.

Rocks larger than 6 inches in diameter, trash, weeds, and other debris that will interfere with seeding or maintenance operations shall be removed or disposed of as specified in section 6.

Seedbed preparation shall be discontinued when soil moisture conditions are not suitable for the preparation of a satisfactory seedbed as determined by the engineer.

5. Seeding, sprigging, fertilizing, mulching, and stabilizing All seeding or sprigging operations shall be performed in such a manner that the seed or sprigs are applied in the specified quantities uniformly in the designated areas. The method and rate of seed application shall be as specified in section 6. Unless otherwise specified, seeding or sprigging shall be accomplished within 2 days after final grading is completed and approved.

The rate, amount, and kind of mulching or mesh shall be as specified in section 6. Mulches shall be applied uniformly to the designated areas. They shall be applied to areas seeded not later than 2 working days after seeding has been performed. Straw mulch material shall be stabilized within 24 hours of application using a mulch crimper or equivalent anchoring tool or by a suitable tackifier. When the mulch crimper or equivalent anchoring tool is used, it shall have straight blades and be the type manufactured expressly for and capable of firmly punching the mulch into the soil. Where the equipment can be safely operated, it shall be operated on the contour. Hand methods shall be used where equipment cannot safely operate to perform the work required.

The tackifier shall be applied uniformly over the mulch material at the specified rate, or it shall be injected into the mulch material as it is being applied. Mesh or netting stabilizing materials shall be applied smoothly, but loosely on the designated areas. The edges of these materials shall be buried or securely anchored using spikes or staples as specified in section 6.

The contractor shall maintain the mesh or netting areas until all work under the contract has been completed and accepted. Maintenance shall consist of the repair of areas damaged by water erosion, wind, fire, or other causes. Such areas shall be repaired to reestablish the intended condition and to the design lines and grades required by the contract. The areas shall be re-fertilized, re-seeded, and re-mulched before the new application of the mesh or netting.

6. Measurement and payment

Method —For items of work for which lump sum prices are established in the contract, payment will be prorated and provided in equal amounts on each monthly progress payment estimate. The number of months used for prorating shall be the number estimated to complete the work as

NRCS-Minnesota (210-VI-NEH, May 2005) MN6-3 outlined in the contractor's approved construction schedule. The final month's prorate amount will be provided with the final contract payment. Payment as described will constitute full compensation for completion of the work.

7. Construction details Seed all the disturbed and grading areas and side slopes of the construction area.

Mulch earth construction areas and earthen spillways with clean straw free of weed seed as described in section 5. Straw mulch shall be applied at two tons/acre to achieve at least 90 percent soil coverage and crimped into the soil to prevent wind and rain displacement.

The seeding mixture shall consist of the following species, varieties and rates of Pure Live Seed per acre.

Nurse Crop—Seed Oats at rate of 1 bushel per acre.

Common Name Scientific Name Sod/Bunch Lbs Per Acre Side-oats Grama Bouteloua curtipendula Sod 4 Switchgrass Panicum virgatum Sod 4 Western Wheatgrass Pascoptrum smithii Sod 5 Canada Wildrye Eltmus canadensis Bunch 7

Seeding dates Spring May 1st -- Sept 1st Summer N/A (cover crop) Dormant Nov. 1 – Freeze-up

No permanent seeding will take place during the period of Sept 1st through October 31th. A cover crop shall be seeded during this time, with a permanent seeding done as soon as possible at the next seeding window.

Seeding Method—Apply seed uniformly at the specified rate by broadcasting or drilling. Harrow lightly following the seeding operation to cover the seed unless the cultipacker seeder equipment cannot operate then cover the seed by hand using a rake or similar tool or a drag behind an ATV.

Mulch Certification—Mulch shall consist of clean grain oat or wheat straw that is certified by the Minnesota Crop Improvement Association (MCIA) to be noxious weed free. For information on obtaining certified mulch or getting a source of straw mulch certified go to the web address:

http://www.mncia.org/noxious-weed-seed-free-forage-mulch

Payment will be lump sum for each of the following

• Disturbed Area Seeding

• Mulching

Seeding of a cover crop is subsidiary to disturbed area seeding and will not result in additional payment.

NRCS-Minnesota (210-VI-NEH, May 2005) MN23-1

Minnesota Construction Specification 23—Earthfill

The work consists of the construction of earth embankments, other earthfills, and earth backfills required by the drawings and specifications.

Earthfill is composed of natural earth materials that can be placed and compacted by construction equipment operated in a conventional manner.

Earth backfill is composed of natural earth material placed and compacted in confined spaces or adjacent to structures (including pipes) by hand tamping, manually directed power tampers or vibrating plates, or their equivalent.

2. Material specifications All fill material shall be obtained from required excavations and designated borrow areas. The selection, blending, routing, and disposition of material in the various fills shall be subject to approval by the engineer.

Fill materials shall contain no frozen soil, sod, brush, roots, or other perishable material. Rock particles larger than the maximum size specified for each type of fill shall be removed prior to compaction of the fill.

The types of material used in the various fills shall be as listed and described in the specifications and drawings.

3. Foundation preparation Foundations for earthfill shall be stripped to remove vegetation and other unsuitable material or shall be excavated as specified.

Except as otherwise specified, earth foundation surfaces shall be graded to remove surface irregularities and shall be scarified parallel to the axis of the fill or otherwise acceptably scored and loosened to a minimum depth of 2 inches. The moisture content of the loosened material shall be controlled as specified for the earthfill, and the surface material of the foundation shall be compacted and bonded with the first layer of earthfill as specified for subsequent layers of earthfill.

Earth abutment surfaces shall be free of loose, uncompacted earth in excess of 2 inches in depth normal to the slope and shall be at such a moisture content that the earthfill can be compacted against them to produce a good bond between the fill and the abutments.

Rock foundation and abutment surfaces shall be cleared of all loose material by hand or other effective means and shall be free of standing water when fill is placed upon them. Occasional rock outcrops in earth foundations for earthfill, except in dams and other structures designed to restrain the movement of water, shall not require special treatment if they do not interfere with compaction of the foundation and initial layers of the fill or the bond between the foundation and the fill.

Foundation and abutment surfaces shall be no steeper than one horizontal to one vertical unless otherwise specified. Test pits or other cavities shall be filled with compacted earthfill conforming to the specifications for the earthfill to be placed upon the foundation.

4. Placement

NRCS-Minnesota (210-VI-NEH, May 2005) MN23-2

Earthfill shall not be placed until the required excavation and foundation preparation have been completed and the foundation has been inspected and approved by the engineer. Earthfill shall not be placed upon a frozen surface nor shall snow, ice, or frozen material be incorporated in the earthfill matrix.

Earthfill shall be placed in approximately horizontal layers. The thickness of each layer before compaction shall not exceed the maximum thickness specified in section 9 or shown on the drawings.

Materials placed by dumping in piles or windrows shall be spread uniformly to not more than the specified thickness before being compacted.

Hand compacted earth backfill shall be placed in layers whose thickness before compaction does not exceed the maximum thickness specified for layers of earth backfill compacted by manually directed power tampers.

Earth backfill shall be placed in a manner that prevents damage to the structures and allows the structures to assume the loads from the earth backfill gradually and uniformly. The height of the earth backfill adjacent to a structure shall be increased at approximately the same rate on all sides of the structure.

Earthfill and earth backfill in dams, levees, and other structures designed to restrain the movement of water shall be placed to meet the following additional requirements:

(a) The distribution of materials throughout each zone shall be essentially uniform, and the earthfill shall be free from lenses, pockets, streaks, or layers of material differing substantially in texture, moisture content, or gradation from the surrounding material. Zone earthfills shall be constructed concurrently unless otherwise specified.

(b) If the surface of any layer becomes too hard and smooth for proper bond with the succeeding layer, it shall be scarified parallel to the axis of the fill to a depth of not less than 2 inches before the next layer is placed.

(c) The top surface of embankments shall be maintained approximately level during construction with two exceptions: A crown or cross-slope of about 2 percent shall be maintained to ensure effective drainage, or as otherwise specified for drainfill or sectional zones.

(d) Dam embankments shall be constructed in continuous layers from abutment to abutment except where openings to facilitate construction or to allow the passage of streamflow during construction are specifically authorized in the contract.

(e) Embankments built at different levels as described under (c) or (d) above shall be constructed so that the slope of the bonding surfaces between embankment in place and embankment to be placed is not steeper than 3 feet horizontal to 1 foot vertical. The bonding surface of the embankment in place shall be stripped of all material not meeting the requirements of this specification and shall be scarified, moistened, and recompacted when the new earthfill is placed against it. This ensures a good bond with the new earthfill and obtains the specified moisture content and density at the contact of the inplace and new earthfills.

5. Control of moisture content During placement and compaction of earthfill and earth backfill, the moisture content of the material being placed shall be maintained within the specified range.

The application of water to the earthfill material shall be accomplished at the borrow areas insofar as practicable. Water may be applied by sprinkling the material after placement on the earthfill, if necessary. Uniform moisture distribution shall be obtained by disking.

NRCS-Minnesota (210-VI-NEH, May 2005) MN23-3

Material that is too wet when deposited on the earthfill shall either be removed or be dried to the specified moisture content prior to compaction.

If the top surface of the preceding layer of compacted earthfill or a foundation or abutment surface in the zone of contact with the earthfill becomes too dry to permit suitable bond, it shall either be removed or scarified and moistened by sprinkling to an acceptable moisture content before placement of the next layer of earthfill.

6. Compaction Earthfill—Earthfill shall be compacted according to the following requirements for the class of compaction specified:

Class A compaction—Each layer of earthfill shall be compacted as necessary to provide the density of the earthfill matrix not less than the minimum density specified in Section 9 or identified on the drawings. The earthfill matrix is defined as the portion of the earthfill material finer than the maximum particle size used in the compaction test method specified.

Class B compaction—Each layer of earthfill shall be compacted to a mass density not less than the minimum density specified.

Class C compaction—Each layer of earthfill shall be compacted by the specified number of passes of the type and weight of roller or other equipment specified or by an approved equivalent method.

Each pass shall consist of at least one passage of the roller wheel or drum over the entire surface of the layer.

Earth backfill—Earth backfill adjacent to structures shall be compacted to a density equivalent to that of the surrounding inplace earth material or adjacent required earthfill or earth backfill. Compaction shall be accomplished by hand tamping or manually directed power tampers, plate vibrators, walk-behind, miniature, or self-propelled rollers. Unless otherwise specified heavy equipment including backhoe mounted power tampers or vibrating compactors and manually directed vibrating rollers shall not be operated within 2 feet of any structure. Towed or self-propelled vibrating rollers shall not be operated within 5 feet of any structure. Compaction by means of drop weights operating from a crane or hoist is not permitted.

The passage of heavy equipment will not be allowed:

• Over cast-in-place conduits within 14-days after placement of the concrete

• Over cradled or bedded precast conduits within 7 days after placement of the concrete cradle or bedding

• Over any type of conduit until the backfill has been placed above the top surface of the structure to a height equal to one-half the clear span width of the structure or pipe or 2 feet, whichever is greater, except as may be specified in section 9.

Compacting of earth backfill adjacent to structures shall not be started until the concrete has attained the strength specified in section 9 for this purpose. The strength is determined by compression testing of test cylinders cast by the engineer for this purpose and cured at the work site in the manner specified in ASTM C 31 for determining when a structure may be put into service.

NRCS-Minnesota (210-VI-NEH, May 2005) MN23-4

When the required strength of the concrete is not specified as described above, compaction of earth backfill adjacent to structures shall not be started until the following time intervals have elapsed after placement of the concrete.

Time interval Structure (days)

Vertical or near-vertical walls with earth loading on one side only 14 Walls backfilled on both sides simultaneously 7 Conduits and spillway risers, cast-in-place (with inside forms in place) 7 Conduits and spillway risers, cast-in-place (inside forms removed) 14 Conduits, pre-cast, cradled 2 Conduits, pre-cast, bedded 1 Cantilever outlet bents (backfilled both sides simultaneously) 3

7. Reworking or removal and replacement of defective earthfill Earthfill placed at densities lower than the specified minimum density or at moisture contents outside the specified acceptable range of moisture content or otherwise not conforming to the requirements of the specifications shall be reworked to meet the requirements or removed and replaced by acceptable earthfill. The replacement earthfill and the foundation, abutment, and earthfill surfaces upon which it is placed shall conform to all requirements of this specification for foundation preparation, approval, placement, moisture control, and compaction.

8. Measurement and payment

As described in the contract.

9. Construction details

Earthfill for the berm be Class C fill. Inspector to approve foundation base prior to fill placement.

Class C fill:

Class C Earthfill shall consist primarily from an approved borrow area. The material may be mineral soil from an adjacent area or similar material type. The soil types may be SM, SC, SP-SM, CL or ML.

Organic soil may be used for topsoiling (4-6 inch thickness)

The maximum thickness of a layer of fill before compaction shall be 9 inches except that with a manually directed power tamper it shall be 4 inches.

The maximum size of rock fragments incorporated in the earthfill shall be 6 inches except hand compacted backfill shall have no rock fragments larger than 3 inches.

The moisture content of the earthfill material shall be maintained within the limits required to: (a) prevent bulking of the fill under the action of the hauling or compacting equipment; (b) prevent adherence of the fill to the treads and tracks of the compacting equipment and (c) insure the blending of the fill into a reasonably homogeneous mass.

The moisture content of the fine grained backfill material shall be such that when kneaded in the hand, the soil will form a ball that does not readily separate.

Each layer of fill shall be compacted by routing the hauling and spreading equipment over the fill in such a manner that every point on the surface of each layer of fill will be traversed by not less than 1 tread track of the loaded equipment traveling in a direction parallel to the main axis of the fill.

A settlement allowance has been added to the fill height. No additional height is required.

NRCS-Minnesota (210-VI-NEH, May 2005) MN26-1

Minnesota Construction Specification 26—Topsoiling

The work consists of furnishing and spreading topsoil to specified depths at locations shown on the drawings.

2. Quality of topsoil Topsoil shall consist of friable surface soil reasonably free of grass, roots, weeds, sticks, rocks, or other unsuitable material. Additional quality requirements, if any, are in section 6 of this specification.

3. Furnishing Topsoil shall be salvaged from designated earth surfaces that will be disturbed by construction activities. After designated sites have been cleared and grubbed, the topsoil shall be removed from the designated areas and stockpiled at locations shown on the drawings or acceptable to the engineer.

Unsuitable material encountered during removal of topsoil shall be disposed of at locations shown on the drawings or approved by the engineer, or it will be otherwise hauled and disposed of at locations removed from the construction site. The contractor is responsible for complying with all local rules and regulations and the payment of any and all fees that may result from the disposal at locations outside the construction work limits.

4. Stockpiling Stockpiles of topsoil shall not conflict with the requirements of Construction Specification 5, Pollution Control, when made a part of this contract.

5. Spreading Spreading shall not be performed when the ground or topsoil is frozen, excessively wet, or otherwise in a condition detrimental to uniform spreading operations. Surfaces designated to receive a topsoil application shall be lightly scarified just before the spreading operation. Where compacted earthfills are designated to be topsoiled, the topsoil shall be placed concurrently with the earthfill and shall be bonded to the compacted fill with the compacting equipment.

Following the spreading operation, the topsoil surface shall be left reasonably smooth and without ruts or surface irregularities that could contribute to concentrated waterflow downslope.

6. Measurement and payment Method—For items of work for which lump sum prices are established in the contract, payment is made as the work proceeds and supported by invoices presented by the contractor that reflect actual costs. If the total of all progress payments is less than the lump sum contract prices for this item, the balance remaining for this item will be included in the final contract payment. Payment of the lump sum contract price will constitute full compensation for completion of the work.

7. Construction Details Stripping, stockpiling, and re-spreading topsoil are included in one line item on the bid sheet and shall be paid by the lump sum method.

The topsoil shall be salvaged from within the work limits or as shown on the drawings. All areas beneath the embankments will be stripped to a depth of 6 inches minimum or as directed by the technician. The topsoil shall be spread to a minimum depth of 0.3 ft. (4 inches) on the earthfill and excavations. The maximum size of rock fragments shall be 3 inches.