Water & Sediment Control Basin

(WASCOB)Mike Cox

State Conservation Engineer

Contractor Certification

Training

March 2008

Purpose: 1) Reduce gully erosion 2) Trap Sediment 3) Reduce and manage downstream runoff

Water & Sediment Control Basin (638)

WASCOBs are typically used when drainage

areas are smaller.

WASCOB Spacing is to reduce slope length and accommodate equipment width

Farmed - WASCOB

• Slopes are flatter (5:1 to 10:1)• More yardage must be used during construction• Harder to fit into steep areas

Grassed - WASCOB

• Slopes are steeper (3:1 to 5:1)• Less yardage used during construction• Fits better into steep areas• Slopes steeper than 5:1 must be grassed

Compaction of Earth Fill

• Use 6-9” Lifts• Dozer or Loaded Pan on Each Lift – 2 passes• Sheepsfoot Roller – 1 pass

Borrow Areas

• Don’t get borrow at the channel– Unless plans call for the channel to be excavated

• Borrow should come from field above• Remember to stockpile topsoil

Outlets for WASCOBs

• Underground Outlet (620)• Outlet tile is sized per orifice diameter• Orifice plates must be installed

Risers

• Must be minimum of 2.5’ in height

Installation Report http://www.in.nrcs.usda.gov/technical/engineering/engineering.html

Look Under Contractor Certification Section

Landowner:WASCoB Number:TBM # and description:TBM Elev: TBM reading: HI:

Orifice diameter: Orifice elev.: Outlet tile diam:Riser diameter: Riser height: Outlet tile elev at riser:

Channel RidgeRod Rod Description

I certify that I have constructed the WASCoB in accordance with this report and the NRCS plans and specifications.Contractor: Signature: Date:

(print name)

ElevationStation Elevation

PROFILE

WASCoB CONSTRUCTION CHECKOUT SHEET

Construction Tolerances-WASCOB

Orifice Elevation: +0.1 foot

Levee Width: Planned width or wider

Top of Levee: Grade or above  

Side Slopes:     Planned slope or flatter  

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