NATURAL RESOURCES CONSERVATION SERVICE



Natural Resources Conservation Service

ILLINOIS CONSTRUCTION SPECIFICATION

WETLAND RESTORATION

Scope

The work consists of excavation and earthfill, along with furnishing and installing pipe and appurtenances for the wetland restoration as shown on the drawings and specified herein.

Utilities

The landowner and/or contractor is responsible for locating all buried utilities in the project area, including drainage tile and other structural measures. The landowner will obtain all necessary permissions from regulatory agencies, or document that no permits are required.

General

CARRY OUT CONSTRUCTION OPERATIONS IN A MANNER AND SEQUENCE THAT EROSION, AIR AND WATER POLLUTION ARE MINIMIZED AND HELD WITHIN LEGAL LIMITS.

The completed job must present a workmanlike appearance and conform to the line, grades, and elevations shown on the drawings or as staked in the field.

Carry out all operations in a safe and skillful manner. Observe safety and health regulations and use appropriate safety measures. Contractor must assure that all state laws concerning buried utilities have been met.

Save documentation of materials used (rock or concrete delivery tickets, geotextile tags, seed tags, photographs of pipe labeling, etc) and provide to NRCS.

Remove all trees, stumps, roots, brush, weeds, and other objectionable materials from work area as designated in the drawings.

Strip designated locations for excavation and earthfill of all vegetation and topsoil containing substantial amounts of organic matter. Stockpile topsoil for use to finish areas disturbed by the construction, embankment slopes, and other required topsoil areas (if the percentage of organic materials is not too great).

Excavation

TO THE EXTENT THEY ARE SUITABLE AND APPROVED BY THE INSPECTOR, EXCAVATED MATERIALS ARE TO BE USED AS FILL MATERIALS.

Place, spread, level, or shape excess spoil material as shown on the construction drawings or as staked in the field. Spoil material must not be spread on existing wetland areas. The completed job must be finished to a degree so the surface can be traveled with farm-type equipment unless otherwise specified in the construction plans.

All excavations must conform to the lines, grades, elevations, bottom width, and side slopes shown on the construction plans or as staked in the field.

The location, extent, and depth of the borrow area must conform to the construction plans or as staked in the field. Borrow must not be taken within 10 feet of the embankment unless shown on the drawings.

Excavate and dress borrow pits in a manner to eliminate steep or unstable side slopes or other hazardous conditions. Side slopes of borrow pits must be no steeper than 3:1 or as specified on the construction plans. Grade and shape surfaces of the borrow pits outside of the wetland area to prevent the ponding of water unless otherwise shown in the construction plans.

Existing Subsurface Drains

Remove subsurface drains as shown on the drawings. Remove all envelope, filter material or other flow-enhancing material. Fill trench in 12 inch lifts of similar soils and compact to achieve a density equal to the adjacent natural soils.

Block the ends of abandoned and disconnected drains with manufactured caps or plugs, plug with concrete, or otherwise seal and make inoperable such that the water holding integrity of the wetland is not impaired.

Existing drains found during construction and not identified on the construction plans must be brought to the attention of the NRCS inspector.

Water Control Structure and Pipe

The materials and manufacture of water control structures, pipe, coupling bands, coatings, and other appurtenances must be as shown on the construction plans and conform to the NRCS material specifications.

Place water control structure and pipe couplers on a stable base. The base may be compacted earth, compacted fill sand, or concrete pad. Extend the stable base no less than 1 foot around structure.

Install structure with all stop boards in tracks. Place impervious backfill material around the structure and other appurtenances by hand and in layers not more than four (4) inches thick before compaction. Thoroughly compact each layer, by means of hand tamping, to the same density requirements as specified for the adjacent embankment. Achieve proper compaction around structure without the use of mechanical compaction.

Increase height of fill at approximately the same rate on all sides of the structure. Heavy equipment must not be operated within 2 feet of any structure.

Lay the pipe to the lines, grades, and elevations shown on the drawings and bed the pipes firmly and uniformly throughout their entire length. Install the pipe according to the manufacturer's instructions.

Select anti-seep collars composed of materials compatible with that of the pipe and install anti-seep collars so that they are watertight.

Install pipe with the outside laps of circumferential joints pointing upstream and with longitudinal laps on the sides at approximately the vertical mid-height of the pipe. Field welding of corrugated galvanized steel pipe will not be permitted. Join pipe sections with coupling bands or other approved methods, as shown on the construction drawings. All pipe connections must be watertight.

The following reference specifications pertain to conduit materials currently acceptable for use.

|REFERENCE SPECIFICATIONS FOR CONDUIT MATERIALS |

|Description |ASTM |

|Plastic |

|Corrugated Polyethylene (PE) Pipe and Fittings |F405 |

| |F667 |

|Poly Vinyl Chloride (PVC) Pipe |F949 |

|and Fittings |D1785 |

| |D2241 |

|Styrene-Rubber (SR) Plastic | D2852 |

|Drain Pipe and Fittings | |

|Dual Wall Polyethylene Pipe |

|Corrugated Polyethylene (PE) Pipe and Fittings |F2306 |

| |F2648 |

| |F405 F667 |

|Elastomeric Seals and Joints (Gaskets) |F477 |

| |D3212 |

|Clay |

|Clay Drain Tile and Pipe |C4 C700 C301|

|Concrete |

|Concrete Drain Tile and Pipe |C412 |

| |C118 C14 C76|

| |C444 |

|Test Methods for Concrete Pipe |C497 |

|Portland Cement |C150 |

|Metal |

|Corrugated Aluminum Pipe |B745 |

|Corrugated Steel Pipe |A760 |

Take special care during backfill operations not to disturb the grade and alignment. Tie down or load pipe sufficiently during backfilling around the sides to prevent its being lifted from the bedding.

Backfill material will have sufficient moisture so that optimum compaction can be obtained. Add water to backfill as necessary to achieve desired moisture content. Place backfill around the pipe and anti-seep collars in layers not more than 4 inches thick before compaction.

Compact each layer of backfill with power tampers, hand tampers, or plate vibrators to the same density requirements as specified for the adjacent embankment. Select compaction method based on soil type. Bring up backfill over and around the pipe and anti-seep collar uniformly on all sides. The passage of earth moving equipment will not be allowed over the pipe or anti-seep collar until backfill has been placed above the top of the pipe or collar to a depth of two (2) feet.

Hand tamping, only, should be used to compact the fill under the bottom half of circular pipes. Do not operate equipment weighing 400 pounds or more per foot of width within 2 feet of any structure or pipe.

Animal Guards

All inlet and outlet pipes must have animal guards, as shown on the construction drawings. Guards on outlet pipe must allow passage of debris. Install all animal guards to manufacturer specifications.

Earthfill

SCARIFY THE FOUNDATION AREA WHERE THE EMBANKMENT IS TO BE BUILT TO A MINIMUM DEPTH OF 4 INCHES BEFORE THE FILL MATERIAL IS PLACED, SO THAT THE FIRST LAYER OF FILL MATERIAL CAN BE BONDED TO THE FOUNDATION.

Fill material must be free of detrimental amounts of sod, roots, frozen soil, stones more than 6 inches in diameter, and other objectionable material that might endanger the performance of the embankment. The moisture content of the fill material must be sufficient to permit satisfactory compaction. Moisture content can generally be considered satisfactory if fill material can be molded into a ball with the hands without readily separating or squeezing out free water, and will easily ribbon out between the thumb and finger. Material that is too wet must be dried and material that is too dry must have water added and mixed until the requirements are met.

Place and spread fill starting at the lowest point of the foundation and bring fill up in horizontal layers not to exceed 9 inches in thickness prior to compaction. Compact each lift by routing hauling equipment over the fill in such a manner that the entire surface will be traversed by not less than one wheel track.

The completed work must conform to the lines, grades, and elevations shown on the construction drawings or as staked in the field.

Auxiliary Spillway Lining

WHERE SPECIFIED ON THE CONSTRUCTION PLANS, AUXILIARY SPILLWAYS ARE TO BE LINED WITH PROTECTIVE MATERIALS SUCH AS TURF REINFORCEMENT MAT (TRM) OR GEOTEXTILE-LINED ROCK. IF TRM IS SPECIFIED, INSTALL TRM ACCORDING TO THE CONSTRUCTION PLANS AND MANUFACTURER’S SPECIFICATIONS.

Geotextile

If geotextile is specified on the construction plans, geotextile must be nonwoven, needle-punched, and meet the minimum criteria specified in the plan.

Place geotextile fabric on the base/subgrade as shown on the drawings, over and outside of the entire area of base/subgrade. The fabric must be loosely laid (not stretched). No cuts or punctures in the fabric will be permitted. Fabric edges should extend at least 12 inches past the edges of the rock when laid. Use a minimum lap of 18 inches if the filter fabric is installed in more than one piece, with upstream or upslope geotextile laid over the downslope geotextile.

Geotextile fabric must not be left exposed for more than 48 hours.

Rock Riprap

If rock is specified on the construction plans, rock must be dense; sound; and free from cracks, seams, or other defects conducive to accelerated weathering. The rock fragments must be angular to sub-round in shape with the least dimensions not less than 1/3 the greatest dimension of the fragment. Riprap will meet the IDOT gradation and quality designation shown on the plans.

Place the rock to the depths specified on the drawings. Construct the riprap to the full course thickness in one operation and in such a manner as to avoid serious displacement of the underlying materials. The rock in place must be reasonably homogeneous with the larger rocks uniformly distributed and firmly in contact one to another and with the smaller rocks filling the voids. Some hand placing may be required to provide a neat and uniform surface. Place rock riprap in a manner to prevent damage to geotextile.

Vegetation

ADD TOPSOIL, IF NEEDED TO ESTABLISH VEGETATION. ESTABLISH A PROTECTIVE COVER OF VEGETATION ON ALL EXPOSED SURFACES OF THE EMBANKMENT, SPILLWAY, OUTLET CHANNEL, AND BORROW AREAS EXPOSED ABOVE THE PERMANENT WATERLINE AND NON-CROP AREAS DISTURBED BY CONSTRUCTION, AS SPECIFIED IN THE CONSTRUCTION PLANS. ESTABLISH VEGETATION AS SOON AFTER CONSTRUCTION AS POSSIBLE.

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