To the editor:
Great issue (February/March 2013), read it from cover to cover.
One thing I noticed though, on page 40 it states: “..were made of polypropylene, which has a specific gravity greater than 1,…” is incorrect. Typically polypropylene has a sg of 0.905 and that is why it floats, not sinks, as alluded to in the article.Â
Have a good one and, again, great issue!
Russ Sutton, P.E.
Civil Engineer–Water, Wastewater & Utilities
U.S. Forest Service–Region 9 Technical Services Team
Correct sentence from February/March Geosynthetics:
Because the geotextiles that were used in this project were made of polypropylene, which has a specific gravity less than 1, UESI had to find a solution that would allow erosion control protection under the waterline while ensuring that the products would stay in position during the service life of the project.