Construction Specifications.pdf

NATURAL RESOURCES CONSERVATION SERVICE

CONSTRUCTION SPECIFICATIONS

For

___________________ County, Iowa

List of Specifications

Specification Number Title Pages

These specifications are part of the construction plans. The work shall be performed in accordance with the drawings and specifications unless otherwise approved, in writing, by NRCS. For items of work requiring NRCS inspection, it is the responsibility of the contractor to keep the local NRCS office informed of the progress of work so that timely inspections may be performed. Work installed without NRCS inspection will not be certified as meeting NRCS standards.

NRCS, IA SPECIFICATION - Page 1 of 2 July 2013

Construction Specification

000 IA-1 Site Preparation

1. SCOPE

Site preparation work shall consist of clearing, grubbing, stripping, refuse removal, bank sloping and structure removal on the site as necessary to rid the site of all undesirable materials on or near the surface and prepare the site for the structure. All woody growth within the construction area shall be cleared and all stumps and roots one inch in diameter or larger shall be grubbed from the site. In addition, all areas within 25 feet of the footprint of the structure shall be cleared and grubbed except as directed by

NRCS. The work shall also consist of the removal and disposal of structures (including fences) that must be removed to perform other items of work.

For wetland restoration, enhancement, or creation projects, the wetland area shall be disturbed as little as possible and existing naturally vegetated spillway areas shall not be disturbed.

2. FOUNDATION PREPARATION

The construction areas shall be stripped a minimum of 6 inches to remove all unsuitable materials such as organic matter, grasses, weeds, sod, debris, and stones larger than 6 inches in diameter.

In an earth embankment foundation area, all channel banks and sharp breaks shall be sloped to no steeper than 1.5 horizontal to 1 vertical.

The foundation area shall be thoroughly scarified before placement of fill material. The surface shall have moisture added or shall be compacted if necessary so that the first layer of fill material can be compacted and bonded to the foundation.

3. STRIPPED MATERIAL DISPOSAL

Suitable soil material shall be stockpiled for use as topsoil. The other stripped materials shall be buried, removed from the site, or disposed of as directed by the owner or NRCS. Whenever possible, material shall not be disposed of in the pool area created by the structure.

Stockpiled materials around a construction site should be placed so as not to hinder subsequent construction operations.

4. DISPOSAL OF REFUSE MATERIALS

Waste materials from clearing and structure removal shall be burned or buried at locations approved by the owner. Buried materials shall be covered with a minimum of 2 feet of earthfill. Whenever possible, material shall not be disposed of in any pool area created by the structure.

All refuse shall be disposed of in a manner which complies with all local and state regulations.

5. SALVAGE

Items to be salvaged shall be as shown on the drawings. Structures and fencing materials that are designated to be salvaged shall be carefully removed and neatly placed in the specified storage areas.

Natural Resources Conservation Service

NRCS, IA July 2013SPECIFICATION - Page 2 of 2

Specific Site Requirements

NRCS, IA SPECIFICATION - Page 1 of 2 February 2011

000 IA-3 Structure Removal

1. SCOPE

The work shall consist of the removal, salvage and/or disposal of structures (including fences) from the designated areas and as indicated on the drawings.

2. MARKING

Each structure or item to be removed will be marked by means of stakes, flags, painted markers or other suitable methods.

3. REMOVAL

All structures designated for removal shall be removed to the specified extent and depth.

4. SALVAGE

Structures that are designated to be salvaged shall be carefully removed and neatly placed in the specified storage areas. Salvaged structures that are capable of being disassembled shall be dismantled into individual members or sections. Such structures shall be neatly match marked with paint prior to disassembly. All pins, nuts, bolts, washers, plates and other loose parts shall be marked or tagged to indicate their proper location in the structure and shall be fastened to the appropriate structural member or packed in suitable containers. Materials from fences designated to be salvaged shall be placed outside the work area on the property from which they are removed. Wire shall be rolled into uniform rolls of convenient size. Posts and rails shall be neatly piled.

5. DISPOSAL OF REFUSE MATERIALS

Refuse materials resulting from structure removal shall be burned or buried at locations shown on the drawings. Buried materials shall be covered with a minimum of 2 feet of earthfill. Whenever possible, material shall not be disposed of in the pool area created by the structure.

All refuse shall be disposed of in a manner which complies with all local and state regulations.

NRCS, IA February 2011SPECIFICATION - Page 2 of 2

NRCS, IA SPECIFICATION - Page 1 of 3 February 2011

000 000 IA CS-005 Pollution Control 2011

1. SCOPE

The work shall consist of installing measures or performing work to control erosion and minimize the production of sediment and other pollutants to water and air during construction operations.

2. MATERIALS

All materials furnished shall meet the requirements shown on the drawings or in the specifications.

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 so that areas unprotected from erosion will be minimized. These areas will be unprotected for the shortest time feasible.

Seeding: Structures and disturbed areas shall be seeded as soon as possible after construction is completed.

Temporary seedings may be used as an alternative to other stabilization measures as approved by

NRCS.

Mulching: Construction areas that have been disturbed but have no construction activity scheduled for

21 days or more shall have erosion protection measures applied by the 14th day. This erosion protection may be mulching or other approved temporary measures. Construction areas shall not be left open during a winter shutdown period and shall be protected by mulching.

All seeding and mulching shall be completed in accordance with the seeding plan and Iowa Construction

Specification IA-6, Seeding and Mulching for Protective Cover.

The following works may be temporary. If they are installed as a temporary measure, they shall be removed and the area restored to its original state when they are no longer needed or when permanent measures are installed.

Diversions: Diversions may be required to divert clean runoff water away from work areas and to collect runoff from work areas for treatment and safe disposition.

Stream Crossings: Culverts or bridges may be required where construction equipment must cross streams.

Sediment Basins: Sediment basins may be required to settle and filter out sediment from eroding areas to protect properties and streams below the construction site.

Sediment Filters: Straw bale filters, geotextile sediment fences, or other equivalent methods may be used to trap sediment from areas of limited runoff. Sediment filters shall be properly anchored to prevent erosion under them.

Waterways: Waterways may be required for the safe removal of runoff from fields, diversions, and other structures or measures.

4. CHEMICAL POLLUTION

The Contractor shall provide watertight tanks or barrels or construct a sump sealed with plastic sheets to be used to dispose of chemical pollutants, such as drained lubricating or transmission oils, greases, soaps, concrete mixer wash water, asphalt, etc., produced as a by-product of the construction work.

At the completion of the construction work, sumps shall be removed and the area restored without causing pollution.

Sanitary facilities such as chemical toilets or septic tanks shall not be placed adjacent to live streams, wells, or springs. They shall be located at a distance sufficient to prevent contamination of any water sources. At the completion of construction work, facilities shall be disposed of without causing pollution.

5. AIR POLLUTION

The burning of brush or trash or disposal of other materials shall adhere to local and state regulations.

Fire prevention measures shall be taken to prevent the start or the spreading of wild fires, which result from project work. Fire breaks or guards shall be constructed 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 insure safe operations at all times. If chemical dust suppressants are used, 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 five working days before use.

6. MAINTENANCE, REMOVAL, AND RESTORATION

All pollution control measures and works shall be adequately maintained in a functional condition as long as needed during the construction operation. All temporary measures shall be removed and the site restored to as near original conditions as practical.

NRCS, IA February 2011SPECIFICATION - Page 2 of 3

NRCS, IA February 2011SPECIFICATION - Page 3 of 3

000 IA-6 Seeding and Mulching for Protective Cover

1. SCOPE

The work shall consist of seeding, mulching, and fertilizing all disturbed areas and other areas as indicated on the drawings or otherwise designated.

2. SEEDBED PREPARATION AND APPLICATION

The entire area to be seeded shall be reasonably smooth and all washes and gullies shall be filled to conform to the desired cross-section before actual seedbed preparation is begun. At this stage of the operation, the required fertilizer and lime shall be applied uniformly and incorporated into the top 3 inches of the soil with suitable tillage equipment. The seedbed preparation operation shall be suspended when the soil is too wet or too dry. The seedbed shall be loosened to a depth of at least three inches.

On side slopes steeper than 2-1/2 horizontal to1 vertical, the 3 inch minimum depth of seedbed preparation is not required, but the soil shall be worked enough to insure sufficient loose soil to provide adequate seed cover.

Unless otherwise specified, the seeding operation shall be performed immediately after preparation of the seedbed. The seed shall be drilled or broadcast by equipment that will insure uniform distribution of the seed.

3. MATERIALS

The seeding, fertilizing, and mulching requirements are as specified on Form IA-CPA-4.

Straw from cereal grains or hay will be used as mulching material. It shall be relatively free of weeds.

4. MULCH APPLICATION

The required mulching shall be performed as soon as possible after seeding unless otherwise specified.

The mulch shall be applied uniformly over the area. The type and rate shall be as specified. When mulching is required, all areas seeded during any one day shall be mulched within 24 hours. The mulch may be spread by any means that results in a uniform cover.

The mulch shall be anchored. Anchoring of the mulch may be performed by a mulch anchoring tool or regular farm disk weighted and set nearly straight, by installation of mulch netting, or by other methods approved by NRCS.

Site 1

Site 2

Site 3

Site 4

210-VI-NEH SPECIFICATIONS CS-008, Page 1 of 2 May 2001

CONSTRUCTION SPECIFICATION

Construction Specification 8—Mobilization and Demobilization

1. SCOPE

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

A. Measurement and Payment

Compensation for any work item described in the contract documents but not listed in the bid schedule will be included in the payment for the item of work to which it is made subsidiary. Such items and bid items to which they are made subsidiary are identified in Items of Work and Construction Details section of this specification.

210-VI-NEH SPECIFICATIONS CS-008, Page 2 of 2 May 2001

For items of work which lump sum prices are established in the contract, the quantity of work will not be measured for payment. Payment for each item will be made at the contract lump sum price and will constitute full compensation for completion of the work.

For items of work for which specific unit prices are established in the contract, the payment will be made based on the approved quantity measured by the engineer or weight tickets. Payment will constitute full compensation of the work completed as defined by each work item.

B. Items of Work and Construction Details

1. Bid Item No. 2

This item shall consist of mobilizing and demobilizing personnel and equipment in preparation to perform the work within the scope of this contract. Mobilization and demobilization for seeding is incidental to this item.

Any work that is necessary to provide access to the site including, but not limited to, grading, temporary culverts, and clearing will be included in this item. When construction is completed access areas will be restored, as close as practical, to its original condition.

Any fence removed for access and /or to provide work area shall be replaced with same or like materials as approved by the engineer.

The Contractor shall exercise caution to minimize the amount of damage caused by the grading and clearing operations.

This item shall not include transportation of personnel, equipment and operating supplies within the work limit areas of this contract.

Payment will constitute full compensation for related subsidiary item, Pollution Control.

Payment will be made as the work proceeds and will paid out on the percent of the project complete as the work progresses. Payment of the lump sum contract price for mobilization and demobilization will constitute full compensation for the completion of the work.

Contractor is to contact “Iowa One Call” for utility locations a minimum of two (2) days prior to any excavation/construction. The ticket number must be provided to Engineer.

Iowa SPECIFICATION IA CS-009, Page 1 of 3 December 2014

CONSTRUCTION SPECIFICATION

IA-9 SUBSURFACE DRAIN INVESTIGATION,

REMOVAL, AND REPAIR

The work shall consist of investigation, location, repair, and/or removal of subsurface drains (tile) near new or existing animal waste storage facilities or in wetland restoration, enhancement, or creation project areas, or other situations where subsurface drains may be present.

2. INVESTIGATION AND LOCATION

An inspection trench at least 10 inches wide shall be dug at the location shown on the drawings or as directed by the engineer or his representative. The trench shall be at least 6 feet deep measured from the original ground line, unless otherwise shown on the plans. The Engineer or his representative shall examine the trench and excavated material to identify tile lines.

Size, material, operating condition and direction of flow of each conduit shall be documented. Location and flow line elevation of each conduit shall be surveyed with horizontal and vertical control based on benchmarks shown on the plans.

The inspection trench shall be documented by surveying the natural ground and trench bottom location and elevations at the beginning, end, and every 50 feet for trenches longer than 50 feet.

Backfilling shall not be started without approval of the Engineer. See Section 5 for backfill specifications.

Trench shields, shoring and bracing, or other methods necessary to safeguard the workers and work, and to prevent damage to the existing improvements shall be furnished, placed, and subsequently removed by the contractor.

3. TILE REPAIR

Unless designated for removal, replace damaged conduit with new conduit having equal or greater capacity using material specified in Section 6 or 7. When replacing short sections of clay or concrete tile with single-wall corrugated polyethylene pipe, use the next larger nominal size.

Make connections with manufactured fittings and tight joints. Where joints have gaps that would allow soil to enter, cover the joint with a permanent type material such as coal tar pitch treated roofing paper, fiber glass sheet or mat, or plastic sheet.

If the investigation trench has been excavated below the existing drain grade, backfill the trench with gravel or well-pulverized soil in layers not over four (4) inches thick and tamp by hand or manually directed power tamper to provide a firm foundation for the conduit at the existing grade. Do not backfill with any soil containing broken tile fragments.

Using selected soil free of hard clods, rocks, or frozen soil, hand tamp the backfill material around the haunch of the pipe in layers not over four (4) inches thick to provide support. Hold the conduit in place mechanically while placing excavated material around and over the conduit to ensure proper alignment and grade is maintained.

Complete the backfill operation according to Section 5.

Iowa SPECIFICATION IA CS-009, Page 2 of 3 December 2014

4. TILE REMOVAL

Remove conduits as shown on the plans or directed by the Engineer or his representative, including envelope filter material or other flow enhancing material when present.

Cap or plug the open ends of the disconnected conduit to prevent soil entry when the conduit will continue to function downstream, or otherwise shown on the plans. For a minimum distance of two feet around each sealed conduit end, backfill in layers not over four (4) inches thick and tamp by hand or manually directed power tamper to a density equal to or greater than the surrounding undisturbed soil. Do not backfill with any soil containing broken tile fragments, large stones, frozen material, or large dry clods.

Where tile are located beneath an existing animal waste facility, remove the tile or fill the entire length of tile with concrete or Portland cement grout as shown on the plans. When tile removal is specified, the owner shall contact the Iowa Department of Natural Resources (IDNR) for permission to remove the drainage tile under the structure. The structure shall be emptied of waste or lowered to a point below the tile prior to its removal. The structure must be retested for percolation and the results submitted to IDNR and approval received prior to reusing the structure.

If shown on the plans or directed by the engineer, reroute upstream drain lines so the capacity of the upstream drainage system is maintained. Install conduit in accordance with Iowa Construction Specification IA-46, Tile Drains for Land Drainage.

5. BACKFILL

Compact soil around disturbed tile as specified in Section 3 (Tile Repair) and Section 4 (Tile Removal). Keep the backfill within 5 feet of the conduit free from large stones, frozen material, and large dry clods. Unless otherwise shown on the plans, backfill the remainder of the trench as follows:

For trenches located under or near structures, backfill in 12-inch layers and compact each layer to a density equal to or greater than the surrounding undisturbed soil.

For other locations, backfill the remainder of each trench with the excavated soil material which shall extend above the ground surface and be well rounded over the trench.

6. MATERIALS

Unless otherwise shown on the plans, conduit and fittings used for repair shall conform to the specifications listed in Table 1. Perforated pipe shall have a water inlet area of at least 1 square inch per foot, provided by perforations spaced uniformly along the long axis of the pipe. The perforations shall be circular or slots. Circular perforations shall not exceed 3/16 inch in diameter. Slots shall not be more than 1/8 inch wide.

Table 1. Acceptable pipe for subsurface drain repair

Kind of Pipe# Specification

Corrugated Polyethylene (PE) Pipe and Fittings, 3 to 6 inch ASTM F 405

Corrugated Polyethylene (PE) Pipe and Fittings, 3 to 24 inch ASTM F 667

Corrugated Profile Wall (Dual Wall) Polyethylene (PE) pipe, 2 to 60 inch ASTM F 2648$

Corrugated Profile Wall (Dual Wall) Polyethylene (PE) pipe, 12 to 60 inch ASTM F 2306$

Iowa SPECIFICATION IA CS-009, Page 3 of 3 December 2014

Polyvinyl Chloride (PVC) Plastic Pipe, Schedules 40, 80 and 120 ASTM D 1785

PVC Pressure-Rated Pipe (SDR Series) ASTM D 2241

Clay drain tile ASTM C 4

Concrete drain tile ASTM C 412

#Pipe sizes are nominal and the ranges are inclusive $Pipe conforming to AASHTO M 252 (3 to 10 inch), or AASHTO M 294 (12 to 60 inch) is acceptable.

7. SPECIFIC SITE REQUIREMENTS

000 IA-11 Removal of Water

The work shall consist of the removal of surface water and ground water as needed to perform the required construction in accordance with the plans and specifications.

2. DIVERTING SURFACE WATER

The Contractor shall build, maintain and operate all cofferdams, channels, diversions, flumes, sumps, and other temporary protective works needed to divert surface water away from the construction site while construction is in progress.

3. DEWATERING THE CONSTRUCTION SITE

Foundations, cutoff trenches, borrow areas and other parts of the construction site shall be dewatered as needed for proper execution of the construction work. The Contractor shall furnish, install, operate and maintain all works and equipment needed to perform the dewatering.

4. EROSION AND POLLUTION CONTROL

Removal of water from the construction site, including the borrow areas shall be accomplished in such a manner that erosion and the transmission of sediment and other pollutants are minimized.

5. REMOVAL OF TEMPORARY WORKS

After temporary works have served their purposes and before the Contractor leaves the site, they shall be removed.

NRCS, IA SPECIFICATION - Page 1 of 2 July 2013

000 IA-21 Excavation

The work shall consist of the excavation required by the drawings and specifications and disposal of the excavated materials. The cutoff trench and any other required excavations shall be dug to the lines and grades shown on the drawings or as staked in the field. Structure or trench excavations will conform to all safety requirements of OSHA.

2. USE OF EXCAVATED MATERIALS

Suitable materials from the specified excavations shall be used in the construction of required permanent earth fill. The suitability of materials for specific purposes shall be determined by the NRCS Inspector.

3. DISPOSAL OF WASTE MATERIAL

All surplus or waste material shall be disposed of in areas shown on the drawings or as approved by the

NRCS Inspector. The waste material shall be smoothed and sloped to provide drainage.

4. STRUCTURE AND TRENCH EXCAVATION

Structure or trench excavations will conform to all safety requirements of OSHA.

5. BORROW EXCAVATION

When the quantities of suitable materials obtained from specified excavations are insufficient to construct the specified fills, additional materials shall be obtained from the designated borrow areas as shown on the drawings or as approved by NRCS and the landowner. On wetland projects, borrow shall not be taken from the wetland area within 10 feet of the embankment or as shown on the drawings.

Borrow areas shall be excavated and grading completed in a manner to eliminate steep or unstable side slopes or hazardous or unsightly conditions.

6. OVER-EXCAVATION

Excavation beyond the specified lines and grades shall be corrected by filling the resulting voids with compacted earthfill, except that if the earth is to become the subgrade for riprap, sand or gravel bedding or drainfill, the voids shall be filled with material conforming to the specifications for the riprap, bedding or drainfill, as appropriate.

NRCS, IA July 2013SPECIFICATION - Page 2 of 2

NRCS, Iowa SPECIFICATION - Page 1 of 4 March 2025

IA-23 Earthfill

1. Scope

The work shall consist of the construction of earth fills required by the drawings and specifications. The completed work must conform to the lines, grades, and elevations shown on the drawings or as staked in the field.

2. Materials Obtain all fill materials from required excavations and designated borrow areas. Fill materials must not contain sod, brush, roots or other bio-degradable materials. Remove rocks larger than 6 inches in diameter prior to compaction of the fill.

3. Foundation Preparation

Strip foundations for earthfill a minimum of 6 inches to remove vegetation and other unsuitable materials. Scarify foundation surfaces to a minimum depth of 2 inches prior to placing fill material.

Do not slope foundation and abutment surfaces steeper than 1.5 horizontal to 1 vertical unless otherwise shown on the drawings.

4. Placement

Do not place fill until the required excavation and foundation preparation have been completed and the foundation has been inspected and approved by NRCS. Do not place fill upon a frozen surface, nor shall snow, ice, or frozen material be incorporated in the fill.

Adjacent to structures or pipes, place fill in a manner which will prevent damage. Increase the height of the fill adjacent to structures or pipes at approximately the same rate on all sides.

The materials used throughout the earth fill must be essentially uniform. Use selective placement as shown on the drawings or approved by NRCS.

If the surface of any layer becomes too hard and smooth for proper bond with the succeeding layer, scarify it to a minimum depth of 2 inches before the next layer is placed.

Maintain the top surfaces of embankments approximately level during construction, except maintaining a cross-slope of approximately 2% to ensure effective drainage.

When moving fill material from the borrow area(s) to the embankment by use of bulldozers only, use the following steps:

• Immediately after the borrow material is pushed to the embankment, spread it in horizontal lifts placed parallel to the centerline of the embankment.

• Compactive effort will then be applied by operating equipment parallel to the centerline of the fill or embankment.

• Lift thicknesses must be in strict compliance with Clause 6, below.

Sectional fills are not allowed unless they are shown on the construction drawings.

5. Control Of Moisture Content The moisture content of the fill material must be adequate for obtaining the required compaction.

Material that is too wet must be dried to meet this requirement, and add water to material that is too dry and mix until the requirement is met.

NRCS, Iowa March 2025 SPECIFICATION - Page 2 of 4

The moisture content of the fill material must be such that a ball formed with the hands does not crack or separate when struck sharply with a pencil and will easily ribbon out between the thumb and finger.

Prevent earth foundations under and adjacent to concrete structures from drying and cracking before concrete and backfill are placed.

Apply water to the fill materials at the borrow areas insofar as possible.

6. Compaction

Compact earth fill by one of the following methods as specified on the plans or in Section 8, Special Specifications. If no method is specified, compaction will be in accordance with Method 1.

• Method 1 – Place earthfill so that the wheels or tracks of the loaded hauling equipment, traveling in a direction parallel to the centerline of fill, pass over the entire surface of each layer being placed.

• Method 2 - Two (2) complete passes of a tamping-type roller will be made over each layer.

The roller must be capable of exerting a minimum of two hundred (200) pounds per square inch.

• Method 3 - Minimum density must be 90% of the maximum density as determined by

ASTM D 698 and as shown on the plans.

The maximum thickness of a lift of fill before compaction is9 inches, unless otherwise indicated on the drawings.

Place fill adjacent to structures, pipe conduits, and appurtenances in layers not more than 4 inches thick and compacted to a density equivalent to that of the surrounding fill.

Methods used to obtain compaction for fine or coarse grained materials are as follows:

• For fine grained materials, hand tamping or manually directed power tampers may be used.

Use hand compaction only to compact the earthfill under the bottom half of circular pipes.

Do not use manually directed power tampers in tight spaces where applying full compactive effort will result in direct contact of the tamper plate with the pipe. Care should be taken so that compaction around the spillway pipe does not cause uplift of the pipe resulting in a void beneath the pipe.

• For coarse grained materials (sands and gravels), use vibratory plate compactors for obtaining compaction. However, use hand tamping to compact the material under the bottom half of circular pipes.

In all cases, follow manufacturer instructions for the specific compaction equipment being used. Do not operate heavy equipment within 2 feet of any structure or pipe.

Do not start compacting of fill adjacent to concrete structures until the concrete is 7 days old.

7. Islands Mounds, And Loafing Areas On Wetland Restoration, Enhancement, Or Creation Projects

Locate islands randomly within the wetland area at locations shown on the drawings or as staked in the field. Locate the orientation of island shorelines randomly with attention given to prevailing winds to limit wave damage. In general, make the side of the island with the longest dimension parallel to the prevailing wind direction. Side slopes of islands must be as shown on the drawings, but in no case will be steeper than 6 horizontal to 1 vertical. Island shapes must be irregular.

NRCS, Iowa March 2025 SPECIFICATION - Page 3 of 4

Construct loafing areas in the areas shown on the drawings or as staked in the field and shall be graded to drain runoff water. The elevation of at least one loafing area should be above the maximum water level whenever possible.

Excavated material not suitable for embankments, wetland dikes, or islands can be used to create mounds or blended into surrounding topography to create a natural appearance. Do not spread spoil material on existing wetland areas.

NRCS, Iowa March 2025 SPECIFICATION - Page 4 of 4

Reset

Site-Specific Requirements

000 IA-26 Topsoiling

The work shall consist of salvaging topsoil from borrow areas or required excavations and spreading it on the exposed disturbed areas.

2. QUALITY OF TOPSOIL

Topsoil shall consist of friable surface soil reasonably free of grass, roots, weeds, sticks, stones, or other foreign materials.

3. EXCAVATION

After the site has been cleared and grubbed, the topsoil shall be removed from borrow areas and required excavation areas to the depth as shown on the drawings. Topsoil shall be stockpiled at locations approved by NRCS.

4. SPREADING

Spreading shall not be done when the ground or topsoil is frozen, excessively wet, or otherwise in a condition detrimental to the work. Surfaces designated to be covered shall be lightly scarified just prior to the spreading operation. Where compacted fills are designated to be covered by topsoil, the topsoil shall be placed concurrently with the fill and shall be bonded to the compacted fill with the equipment.

Topsoil shall be placed to the minimum depth shown on the drawings. After the spreading operation is completed, the surface shall be finished to a reasonably smooth surface.

NRCS, Iowa Specification – Page 1 of 5 December 2025

IA-45 Plastic (PE, PVC) Pipe

The work consists of furnishing and installing plastic pipe and the necessary fittings specified herein or as shown on the drawings. This specification does not cover subsurface drainage systems.

2. MATERIALS

Corrugated Polyethylene (PE) Tubing. Corrugated PE tubing and fittings must conform to the requirements of the applicable specification listed below:

Kind of Pipe Specification

Standard Specification for 3 through 24 in. Corrugated Polyethylene Pipe and Fittings ASTM F667

Standard Specification for Polyethylene (PE) Large Diameter Profile Wall Sewer and Drain Pipe

ASTM F894

Poly(Vinyl Chloride) (PVC) Plastic Pipe. PVC pipe and fittings must conform to the requirements of the applicable specification listed below:

Kind of Pipe Specification

Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40,80, and 120

ASTM D1785

Standard Specification for Poly(Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)

ASTM D2241

Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 in. through 60 in.

for Water Transmission and Distribution

AWWA C900

PVC,PE, and PEX Plastic Pipe. Plastic pipes meant for non-potable irrigation and livestock water supply must conform to the requirements of the applicable specification listed below:

Kind of Pipe Specification

Standard Specification for Polyethylene (PE) Plastic Pipe (SIDR-PR) Based on Controlled Inside Diameter

ASTM D2239

Standard Specification for Polyethylene (PE) Plastic Tubing ASTM D2737

Standard Specification for Polyethylene (PE) Plastic Pipe (DR-PR) Based on Controlled Outside Diameter

ASTM D3035

Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40,80, and 120

ASTM D1785

Standard Specification for Poly(Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)

ASTM D2241

Standard Specification for Crosslinked Polyethylene (PEX) Tubing ASTM F876

3. FITTINGS AND JOINTS

Pipe joints must conform to the details shown on the drawings. Install and join pipe in accordance with the manufacturer’s recommendations.

NRCS, Iowa Specification – Page 2 of 5 December 2025

Joints may be bell and spigot type with elastomeric gaskets, coupling type with elastomeric gasket on each end, or solvent cemented. Gaskets must conform to ASTM D 1869. Do not use solvent cemented joints for pond spillway pipes. Solvent cemented joints for PVC pipe and fittings must be in accordance with ASTM D 2855. When a lubricant is required to facilitate joint assembly, it must be a type having no detrimental effect on the gasket or pipe material.

Mechanical joints (split couplings and snap couplings) may be used when joining PE pipe and fittings when the pipe is used for non-pressure flow and a free draining sand or gravel bedding material is provided.

Elastomeric-sealed mechanical joints must be used when joining PE pipe and fittings under pressure flow or where seepage cannot be tolerated. Where non-pressure pipe is specified, the fittings must be of the same or similar materials as the pipe and shall provide the same durability and strength as the pipe.

A special case of livestock water supply involves pipes through a dam or embankment. Only PE pipe meeting the above specification may be used. Install PE pipe, of 1 ¼, 1 ½, or 2-inch diameter so that there are no joints within the embankment area.

Where pressure pipe is specified, fittings must have a design capacity equal to or exceeding that specified for the pipe to which it is attached. Fittings must be cast iron, steel, one piece injection molded plastic fitting or fabricated from plastic pipe and one piece injection molded plastic fittings. Pressure pipe fittings must conform to the requirements of the applicable specification listed below. Other fittings may be approved by NRCS, but ONLY prior to installation.

Pipe Fittings

Kind of Fitting Specification

Pressure Pipe

Standard Specification for Threaded Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80

ASTM D2464

Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule

ASTM D2466

Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule

ASTM D2467

Standard Specification for Plastic Insert Fittings for Polyethylene (PE) Pipe ASTM D2609

Standard Specification for Socket-Type Polyethylene Fittings for Outside Diameter- Controlled Polyethylene Pipe and Tubing

ASTM D2683

Standard Specification for Joints for Plastic Pressure Pipes Using Flexible Elastrometric Seals

ASTM D3139

Standard Specification for Butt Heat Fusion Polyethylene (PE) Plastic Fittings for Polyethylene (PE) Plastic Pipe and Tubing

ASTM D3261

Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 in. through 60 in.

for Water Transmission and Distribution

AWWA C900

Solvents

Standard Specification for Solvent Cements for Poly(Vinyl Chloride) (PVC) Plastic Piping Systems

ASTM D2564

Standard Practice for the Two-Step (Primer and Solvent Cement) Method of Joining Poly(Vinyl Chloride) (PVC) or Chlorinated Poly(Vinyl Chloride) (CPVC) Pipe and Piping Components with Tapered Sockets

ASTM D2855

All PEX fittings must be approved by NRCS prior to installation N/A

NRCS, Iowa Specification – Page 3 of 5 December 2025

4. HANDLING AND STORAGE

Deliver pipe to the job site and handle by means which provide adequate support to the pipe and does not subject it to undue stresses or damage. When handling and placing plastic pipe, take care to prevent impact blows, abrasion damage, and gouging or cutting (by metal surfaces or rocks). Strictly obvserve all special handling requirements of the manufacturer. Take special care to avoid impact when the pipe must be handled at temperatures of 40 degrees F (4.4 degrees C) or less.

Store pipe on a relatively flat surface so that the barrels are evenly supported. Unless the pipe is specifically coated to withstand exposure to ultraviolet radiation, cover it with an opaque material when stored outdoors for a period of 15 days or longer.

5. TRENCHING

Install plastic pipe conduits in trenches or plowed in according to the following methods:

1. Trencher Constructed - When conditions permit, trenching for pipelines, which are buried from 5 to 6 feet deep, are usually done with a narrow 4 to 6 inch wide chain trencher. Where there is little gravel and the ground is not too wet, these trenchers bring up well pulverized soil that makes good backfill material. Where rocks are not present, any of this material may be backfilled directly around the pipe.

There is no practical way to compact the fill in these narrow trenches. The owner must be made aware that this material normally consolidates to its maximum extent in two to five years, but depressions or low spots can be hazards to livestock, humans and equipment.

2. Backhoe Constructed Trench – Backhoe trenches are usually a minimum of 12 inches wide. The material frequently comes out of the trench as clods, large chunks, and rocks. Immediately backfill over the pipe with 4 to 6 inches of soil that is free of these clods, large chunks, and rocks. If adequate excavated material is not available, then material such as sand or fine gravel should be imported and placed around the pipe to a depth of 4 to 6 inches over the top of the pipe. Fill the trench with the remaining excavated material.

3. Plowing – Plowing, or ripping, is a trenchless method for installing plastic pipe. It is a multi-stage process consisting of positioning a vibrating or static (non-vibrating) plow equipped with a trailing product guide which feeds pipe to the depth setting of the plow as it moves forward. The pipe is inserted into the ground continuously along a predetermined path and depth. The vertical depth of installation is controlled by hydraulic adjustment of the plow shear head and the surface contours. The depth of insertion must be continually adjusted to compensate for changes in terrain.

6. LAYING AND BEDDING THE PIPE

Install plastic pipe conduits and fittings as shown on the drawings and specified herein. Lay the pipe so that there is no reversal of grade between joints, unless otherwise shown on the drawings. Place the pipe with the bell end upstream, unless otherwise specified. Carefully place the pipe on the bedding or into the pipe trench.

Take care to prevent distortion and damage during unusually hot (over 90 degrees F) or cold weather (under 40 degrees F). After the pipe has been assembled in the trench, allow it to reach ground temperature before backfilling to prevent pull out of joints due to thermal contraction.

The pipe ends and the couplings must be free of foreign material when assembled. During the placement of the pipe, close off each open end of the pipeline by a suitable cover or plug at the end of work on the pipeline each day and until work resumes or installation is complete.

Lay perforated pipe with the perforations down and oriented symmetrically about the vertical centerline.

Perforations must be clear of any obstructions when the pipe is laid.

Firmly and uniformly support the pipe throughout the entire length. Make bell-holes in the bedding under bells or couplings and other fittings to prevent the pipe from being supported by fittings.

1. Earth Bedding. When bedding is specified, firmly and uniformly bed the pipe in a shaped bedding groove that closely conforms to the bottom of the pipe for a depth equal to a minimum of 1 inch or 5 percent of the diameter of the pipe, whichever is greater. The bedding material must be free of rocks or stones greater than 0.5 inch diameter and earth clods greater than 2 inch diameter.

NRCS, Iowa Specification – Page 4 of 5 December 2025

2. Sand or Gravel Bedding. When sand or gravel bedding is specified, firmly and uniformly place the pipe on a sand or gravel bed. Carefully place sand or gravel fill and compact as specified herein and as shown on the drawings.

Plastic pipe installed above ground must be designed to withstand exposure to ultraviolet radiation. Install and anchor above ground pipe as detailed in the construction drawings.

Adequate thrust control shall be incorporated in these installations.

7. BACKFILL

Hold the pipe down during backfilling to the top of the pipe to prevent its being lifted from its original placement.

Within 2 feet of the pipe, carefully place and compact backfill by means of hand tamping or manually directed power tampers or plate vibrators to form a continuous uniform support around the pipe. Maximum thickness of layers before compaction within 2 feet of the pipe is 4 inches and at more than 2 feet from the pipe a maximum thickness before compaction is 9 inches. Unless otherwise specified, compact the initial backfill to a density equivalent to that of the adjacent fill or foundation materials.

The water content of cohesive backfill material must be such that, kneaded in the hand, the soil will form a ball which does not readily separate. For non-cohesive sand and gravel backfill material, water content is not a concern for thin lifts.

NRCS, Iowa Specification – Page 5 of 5 December 2025

NRCS, Iowa Specification – Page 1 of 4 December 2025

IA-46 Tile Drains for Land Drainage

The work consists of furnishing and installing drainage pipe (tubing) and tile and the necessary fittings and appurtenances.

2. MATERIALS

Materials must meet the requirements as shown on the drawings. Field inspect for any deficiencies such as thin spots or cracking prior to installation.

Perforated tubing shall have a water inlet area of at least 1 square inch per foot, provided by perforations spaced uniformly along the long axis of the tubing. The perforations shall be circular or slots. Circular perforations shall not exceed 3/16 inch in diameter. Slots shall not be more than 1/8 inch wide.

All pipe material must meet the following reference specifications:

Plastic Pipe

Standard Specification for 3 through 24 in. Corrugated Polyethylene Pipe and Fittings ASTM F667

Standard Specification for 12 to 60 in. Annular Corrugated Profile-Wall Polyethylene (PE) Pipe and Fittings for Non-Pressure Gravity-Flow Storm Sewer and Subsurface Drainage Applications

ASTM F2306

Standard Specification for 2 in. to 60 in. Annular Corrugated Profile Wall Polyethylene (PE) Pipe and Fittings for Land Drainage Applications

ASTM F2648

Standard Specification for 3 through 24 in. Lined Flexible Corrugated Polyethylene Pipe for Land Drainage Applications

ASTM F3390

Standard Specification for Corrugated Polyethylene Drainage Pipe 3”-10” AASHTO M252

Standard Specification for Corrugated Polyethylene Drainage Pipe 12”-60” AASHTO M294

Clay and Concrete Pipe

Standard Specification for Clay Drain Tile and Perforated Clay Drain Tile ASTM C4

Standard Specification Concrete Drain Tile ASTM C412

3. EXCAVATION

Unless otherwise specified, begin excavation for and subsequent installation of each drain line at the outlet end and progress upstream.

Construct the trench or excavation for the conduit to the line, depth, cross section, and grade shown on the drawings, or as directed by the NRCS Inspector. The trench bottom must be smooth and free of exposed rock.

If rock is encountered in the trench bottom, over-excavate the trench and place at least 6 inches of compacted earth or sand bedding in the trench to bring it up to the conduit grade.

If not otherwise shown on the drawings, trench width at the top of the conduit must be the minimum required to permit installation and provide bedding conditions suitable to support the load on the conduit, but with not less than three (3) inches of clearance on each side of the conduit. Maximum trench width is the conduit diameter plus 12 inches measured at the top of the conduit, unless approved bedding is installed.

The contractor must furnish, place, and subsequently remove trench shields, shoring and bracing, or other

NRCS, Iowa Specification – Page 2 of 4 December 2025 methods, necessary to safeguard the workers and work, and to prevent damage to the existing improvements.

Plow installation is allowed. The minimum allowable trench width is two (2) inches wider than the conduit on each side. Grade control and bedding conditions must be closely inspected during plow installation. Boulders, cobbles, or cemented soils can cause the plow to jump and lose grade. These hardpoints can also puncture or dimple and deform the pipe.

4. PREPARING THE BEDDING

Unless otherwise specified, no filter or envelope is required. In stable soils, shape the bottom of the trench to form a semicircular, trapezoidal, or 90-degree “V” groove in its center. Shape the groove to fit the size of tile.

Do not use the 90-degree “V” groove on conduits greater than 6 inches in diameter.

If the bottom of the trench does not provide a sufficiently stable or firm foundation for the drain tile, use a sand-gravel mix or other approved materials to stabilize the bottom of the trench.

5. FILTER OR ENVELOPE MATERIAL

When a filter is specified, the shape of the bottom of the trench, gradation and the thickness of the filter or envelope material to be placed around the conduit will be as shown on the drawings. Place the envelope or filter material in the bottom of the trench just prior to the laying of the conduit. Then lay the conduit and place the envelope or filter material over the conduit.

6. PLACEMENT AND JOINT CONNECTIONS

All drains must be laid to grade.

Joints between lateral concrete and clay drain tiles must vary with soil type as follows:

1. Peat and muck - 1/4 inch preferred, 3/8 inch maximum

2. Clay - 1/8 inch preferred, 1/4 inch maximum

3. Silt and loam - 1/16 inch preferred, 1/8 inch maximum

4. Sand - tightest possible fit.

Joints between main drain tile, which serve only to collect and transport drainage water from lateral tile lines, should be the tightest fit possible.

Where the joint width exceeds the maximum above, cover the joint with a permanent type material such as coal tar pitch treated roofing paper, fiber glass sheet or mat, or plastic sheet.

After placement and blinding of plastic tubing, but prior to backfilling, sufficient time must elapse to allow the tubing to reach the ambient temperature of the trench. Securely tie all split fittings with nylon cord before backfill is placed. When corrugated plastic tubing is used, no more than 5% stretch is allowed.

7. CONNECTIONS

Make lateral connections with manufactured appurtenances (wyes, tees, etc.) comparable in strength and durability with the specified conduit unless otherwise shown on the drawings.

Existing…