Natural Resources Conservation Service

Conservation Practice CONSTRUCTION Specification

DIKE

> CODE 356

1.  **SCOPE**

> The work shall consist of constructing a Class II or Class III dike
> embankment as shown on the drawings. This construction specification
> does not apply to Class I dikes.

2.  **SITE PREPARATION**

Site preparation (mobilization and demobilization, clearing and
grubbing, structure removal, pollution control, and water for
construction) shall be in accordance with Construction Specification
587.

> Preparation of sites for dike construction shall be done in a manner
> that destroys as little vegetation outside the areas to be occupied by
> dikes and borrow pits as feasible. Special efforts shall be made to
> save trees of significant value which are not in the area to be
> occupied by the dike.
>
> A minimum area should be stripped of vegetation at any one time to
> provide an adequate work site and to minimize dust, air borne
> pollution, et cetera.

3.  **FOUNDATION WORK**

> Foundation work (diverting surface water, dewatering the construction
> site, dewatering borrow areas, and foundation preparation) shall be in
> accordance with Construction Specification 587 except that following
> satisfactory completion of clearing operations, all channel banks and
> sharp breaks shall be sloped to no steeper than 2:1.

4.  **EARTHWORK**

> Earthwork (common excavation and earthfill) shall be in accordance
> with Construction Specification 587. Where it is necessary to use
> materials of varying texture and gradation, the more impervious
> material shall be placed in the upstream and center portions of the
> fill.
>
> Compaction of backfill for Class II dikes shall be acceptable when one
> of the following conditions have been met:

-   Making two complete passes over the entire surface area of each lift
    with heavily loaded rubber-tired scrapers.

-   Making three complete passes over the entire surface area of each
    lift with heavily loaded rubber-tired scrapers.

-   Using track type (crawler) equipment provided it is routed so the
    entire surface area of each lift is traversed by not less than four
    passes of the tracks.

> Compaction of backfill for Class III dikes shall be achieved through
> normal routing of rubber-tired or track-type equipment.
>
> Drainfill shall be kept from being contaminated by adjacent soil
> materials during placement by either placing it in a cleanly excavated
> trench, or by keeping the drain at least 1 foot above the adjacent
> earthfill.
>
> When borrow areas are made behind dikes, undisturbed strips of
> compacted plugs shall be placed every 660 feet, or closer as needed,
> to prohibit flow through the borrow area.

5.  **CONDUIT INSTALLATION**

> The pipe conduit barrel shall be placed on a firm foundation to the
> lines and grades shown on the drawings. The pipe conduit material
> shall be as specified or otherwise indicated on the drawings.
>
> The trench for the pipe conduit shall be free of projecting rocks when
> the pipe is installed, and the trench side slopes shall not be steeper
> than 1:1.
>
> All pipe conduit joints shall be watertight.
>
> Select backfill material shall be placed around the conduit in 6-inch
> layers, and each layer shall be thoroughly compacted using hand or
> power driven tampers to a density equaling the undisturbed foundation.
> All backfill material shall be at the moisture content required for
> earthfill.
>
> Filter and drain material shall be as specified or otherwise shown on
> the drawings.

6.  **TOLERANCE**

> The embankments shall be constructed within the following tolerance:

-   All cross-sections of the completed embankment shall equal or exceed
    the neat lines shown on the design.

-   All constructed side slopes of the embankment shall be full-bodied;
    i.e., straight or convex from the edge of the crest to the toe of
    the slope. Slopes designed at 2:1 shall have no slope length steeper
    than 1¾:1. Slopes designed at 3:1 shall have no slope length steeper
    than 2¾:1.

7.  **MEASUREMENT**

> [Site Preparation]{.underline}
>
> There is no measurement for mobilization and demobilization, structure
> removal, pollution control, or water for construction.
>
> The area cleared and grubbed shall be measured to the nearest 0.1
> acre.
>
> [Foundation Work]{.underline}
>
> There is no measurement for diverting surface water, dewatering the
> construction site, or foundation preparation.
>
> [Earthwork]{.underline}
>
> The volume of excavation shall be measured within the specified limits
> and computed to the nearest cubic yard by the method of average
> cross-sectional end areas.
>
> The earthfill volume shall be measured within the specified limits and
> computed to the nearest cubic yard by the method of average
> cross-sectional end areas.
>
> The drainfill volume shall be measured within the specified limits and
> computed to the nearest cubic yard by the method of average
> cross-sectional end areas.
>
> Project Name:
>
> Date:

8.  **ITEMS OF WORK AND CONSTRUCTION DETAILS**

> Items of work to be prepared in conformance with this specification
> and the construction details are: