Vicksburg District Maintenance Part 2

Inlet free of
Adequate scour
protection provided
Inlet free of obstructions
Positive Seal on Flap Gate
Adequate Scour
Tree growth next to levee
Levee Excavations : Approximately 6 to 12 inches of topsoil shall be
removed from the slide area and stockpiled for re-use. The excavation line
must extend at least (1 ft ) below the failure slide plane. At the toe of the
excavated slope, a key approximately (3 ft. ) deep and of minimum width to
be compacted by conventional equipment shall be excavated. The end
slopes of the levee excavation shall be ( 1 ft. ) vertical on (3 ft. ) horizontal
to allow for access and proper compaction. The stockpiled soil shall not
exceed (6 ft ) in height if placed on the existing levee slope.
Preparation of Foundation: All trees, brush, sod, vegetation, decayed
organic matter, stumps and debris of every description shall be removed
from the foundation surfaces. Also, grubbing may be required but is
uncommon for these foundations. The entire earth surface on or against
which levee fill is to be placed, shall be thoroughly broken to a depth of 6
inches. If for any cause, this broken surface becomes compacted a plane
of seepage or weakness might be induced, therefore it shall again be
adequately scarified before depositing material thereon.
Soil Processing Areas: When the size of the slide being repaired permits,
and it is practical , the lime-soil mixture can be processed in lifts in the
embankment and then compacted. Lift thickness shall not exceed 6 to 8
inches. If a processing area is needed to process material removed from
the slide, 4 to 6 inches of topsoil shall be removed from the area and
stockpiled for re-use. The processing area shall be large enough to mix a
minimum of on truck load of lime (approx 24 tons) and be located riverward
of the existing levee.
Spreading and Mixing Lime: After the excavated soil to be treated with lime
is placed in the processing area in 6 to 8 inch layer, checks should be made to
ensure proper moisture content. The dry unit weight of 80 lbs per cubic foot
will be used for the soil to compute the required rate of application of lime by
weight. Approx 4.8 lbs of lime per cubic ft of material should be used. In highly
plastic clays a double application of lime will be required to achieve
satisfactory pulverization. Six percent of more lime will require the double
application method. The first application of lime , which will be one-half the
total recommended percentage, shall be mixed by at least one pass with a
rotary pulverizer and sealed to maintain moisture and allowed to cure for a
minimum of 48 hrs. After the 48 hour curing time the remainder of the lime
shall be added. After application of lime a liberal amount of water shall be
applied over the surface to prevent dusting and achieve good distribution of
the lime. Water shall be added even if the moisture content is above the
optimum moisture content for compaction. A high speed rotary pulverizer
shall be used to mix the soil and lime. Several passes of the rotary pulverizer
may be required. After final mixing of lime with soil, the mixture shall be placed
in the embankment and compacted as soon as possible. When moving the
soil – lime mixture from the processing area precautions shall be taken to
avoid unmixed material. Any lime that has been exposed to the open air for a
period in excess of 6 hours, and lime lost or damaged before soil incorporation
due to rain, wind or other cause should not be used.
Embankment. The lime-soil mixture shall be placed in the levee
embankment by conventional methods. The moisture content of the limesoil mixture, to be compacted, shall be within a specified range. Lift
thicknesses will be limited to 6 to 8 inches. The soil-lime mixture shall be
benched into the existing embankment in a stair stepped pattern at
approximately 1-foot intervals. Each lift shall be compacted by at least
three passes of a crawler type dozer weighing at least 20,000 pounds and
exerting a unit tread pressure of at least 6 pounds per square inch or
other compacting equipment which will attain comparable compaction. A
pass shall consist of one complete coverage of the surface of a layer by
the treads of a dozer or other compacting equipment.
Turfing. After completion of the reconstruction operation, the previously
removed top soils shall be returned and distributed over their primary
locations, and the portions of the levee and berms where the new fill has
been placed shall be fertilized and seeded.
Fertilizing. Prior to seeding, all processing areas, the entire
surface of the repaired portions of the levees, berms, and all
areas distributed shall be fertilized. Fertilizer shall be applied at
the rate of 60 lbs per acre of 13-13-13 commercial fertilizer.
Fertilizer shall be uniformly distributed over the surface and
worked into the top 2 to 4 inches of the soil by light disking or
Seeding. After completion of the fertilizing operation, all
processing areas, the entire surface of the repaired portions of
the levees, berms, and all areas disturbed shall be seeded.
Compaction. After completion of the seeding, the areas of the
levees and berms shall be compacted by making one complete
pass over the entire surface. A pass shall consist of one
complete coverage of the surface by compacting equipment.
Processing lime/soil mixture

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