Sheet Flow Construction Erosion Control

September 8, 2020

Biodegradable Wattles

I wrote this biodegradable wattles specification for a riverbank habitat restoration project.

I wrote the last three sentences for this particular project, which has a 2:1 slope above an intertidal river. We will place 12 inches of compost before installing native plants this winter; without the wattles, wet compost will slide to the base of the slope.

BIODEGRADABLE WATTLES

  1. Wattles shall consist of 100% biodegradable straw, coir, excelsior or compost encased in 100% biodegradable fabric or mesh.
  2.  Wattles shall be a minimum of 8 inches in diameter free of cuts tears and damage.
  3. The installation of straw wattles shall be per WSDOT Standard Plan I-30.30-00 “Wattle Installation on Slope”.
  4. Wattles shall be staked in place using wooden stakes a minimum of 16 inches long.  The stakes shall be cut flush with the top of the wattles.
  5. Wattles shall be installed on the Site 25 slope above +12 elevation.
  6. Wattles shall be installed in two rows across the slope parallel to the 12 + elevation. 
  7. Rows shall be approximately 7 feet above the +12 elevation and 7 feet below the top of the slope.

January 10, 2020

Plastic Netting

I saw this plastic netting today while looking at site we will be working on this summer. The straw wattle was left over from a previous project, completed almost six years ago. The straw filler is almost completely degraded. The netting is partially degraded, but in places is too strong to tear apart with my fingers. We need more 100% biodegradable best management practices and less plastic netting.

Six year old straw wattle. Photo: David Jenkins
Close up of plastic netting. Photo: David Jenkins

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