Quantcast Man-hour Costs of Bioengineering Treatments

 
  
 
Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines
Man-hour Costs of Bioengineering Treatments
Brush Mattress or Matting
The cost of the brush mattress is moderate according to Schiechtl (1980), requiring 2 to
5 man-hours per square metre. In a training session that WES conducted, a crew of 20
students using hand tools installed about 18 sq m of brush mattress at a rate of about 1 man-
hour per square metre. This rate included harvesting the brush, cutting branches into
appropriate lengths, and constructing the mattress. This rate of production compares
favorably to an average rate of .92 sq m of brush mattress per man-hour by a leading
bioengineering firm in the United States.
Brush Layering
There are few references on the cost of brush layering. Schiechtl (1980) reported the cost
to be low, presumably in comparison to techniques using riprap or other similar materials.
In the training session mentioned earlier, a crew of 20 students using hand tools installed
about 20 m of brush layering along one contour-slope in about 30 min. This equates to 2 m
per man-hour. Often, costs can be reduced if machinery such as bulldozers or graders can
gain access to the shoreline site and reduce the hand labor required in digging the trenches.
Then, this would only require workers to fill the trenches with brush, which can also be
covered with machinery.
Wattling Bundles (Fascines) and Cuttings
Leiser (1983) reported man-hour costs for installing wattling and willow cuttings at Lake
Tahoe, California (Table 4). These man-hour costs can be extrapolated to streambanks as
well and run about 6 linear ft of wattling per man-hour and 46 small willow cuttings per
manhour. Robin Sotir1 quoted an average installation rate of 5 linear ft of fascine production
per man-hour. Obviously, if one were to place a coir fabric between contours of wattling
bundles, production rates would decrease substantially. According to Ms Sotir6, who has
done this extensively, it would probably half the amount of linear ft per man-hour.
1
Ms. Robin Sotir, President, Robin Sotir and Associates, Marietta, GA, 2 Aug
1996, personal communication.
B-84

 


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