**CONSTRUCTION SPECIFICATION**

**AR-23M EARTHFILL-CLASS M**

**1. Scope**

> The work shall consist of the construction of compacted earth fills
> where the amount of compaction is to be controlled by specifying a
> construction method.

**2. Materials**

> All fill materials shall be obtained from required excavations and
> designated borrow areas. Selection, blending, placement, and
> compaction of fill will be subject to approval of the inspector.
>
> Fill materials shall contain no frozen material, sod, roots or other
> perishable material, or rocks larger than six inches in diameter. Fill
> shall not be placed on a frozen surface.

**3. Foundation Preparation**

> All foundation (including abutment) surfaces shall be shaped one
> horizontal to one vertical or flatter except as otherwise specified.
>
> After stripping (see stripping specification), the foundation shall be
> loosened thoroughly by scarifying or plowing to a minimum depth of
> four inches. The foundation shall then be compacted by the process
> specified for the fill.

**4. Placement**

> All foundation excavation and preparation shall be completed before
> placing fill. Except as required by the drawings, fill material shall
> be mixed and uniformly placed throughout the entire fill without
> lenses, streaks, pockets, or layers of material that differ
> significantly from surrounding material.
>
> Placement and compaction methods must prevent damage to structures and
> allow the structure to assume backfill loads gradually and uniformly.
> Within 2 feet of any structure, fill layer thickness must not exceed 4
> inches and equipment loads must not exceed 400 pounds.
>
> Fill shall be placed in approximately horizontal layers. Except as
> described above, fill layer thickness shall not exceed nine inches for
> compaction by large machines or four inches for small hand directed
> power tampers.
>
> 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 two inches, before the
> next layer is placed.
>
> Except as otherwise specified, openings temporarily left in dam fills
> (for pipe installation, stream flow, etc.,) shall have side slopes
> three horizontal to one vertical or flatter. When filling the opening,
> the bonding surface of the fill in place shall be stripped of all
> material not meeting the requirements of this specification and shall
> be scarified, moistened, and recompacted as new earthfill is placed.

**5. Control of Moisture Content**

> At the time of compaction, earth fill shall have a moisture content
> that when kneaded in the hand will form a ball that does not easily
> crumble when pressed between the hands. If the soil is too wet, it
> will yield free water when kneaded in the hand.
>
> Fill materials must be wetted or dried as needed to achieve proper
> moisture prior to compaction.

**6. Compaction (Class M)**

Fill layers shall be compacted by one of the following methods.

> **a.** By routing the hauling and spreading equipment such that all
> points of the fill are traversed by at least one tread track of the
> loaded equipment traveling parallel to the centerline of the fill.
>
> **b.** By at least 2 passes of a tamping (sheepsfoot) roller weighing
> at least 100 pounds per square inch of bearing area.
>
> Fill adjacent to structures shall be compacted to a density equivalent
> to that of the surrounding fill by means of hand tamping or manually
> directed power tampers or plate vibrators. Within 2 feet of any
> structure, equipment loads must not exceed 400 pounds.
>
> Compaction of fill adjacent to concrete structures shall not be
> started for at least the following number of days after placement of
> the concrete.

**Concrete Structure Days After Concrete Placement**

> Vertical or near-vertical walls with earth load 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 (forms removed) 14\
> Conduits, pre-cast, cradled 2\
> Conduits, pre-cast, bedded 1\
> Anti-seep collars and cantilever pipe supports (backfill both sides
> simultaneously) 3