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waterline angle of repose of fine to medium sand

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Buckaloo

Civil/Environmental
Dec 16, 2012
1
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CA
The site I'm concerned about is a forested (40-50 foot pitch pine and white oak mix) bay sand dune that is in a tidal zone (+/- 9 inch tide) that had a 25 horizontal feet sand loss due to super storm Sandy. The dune height is 15 feet above high tide and peaks 75 feet (horizontal) back from the high tide mark it drops as two steps of roughly 10-15 wide for the somewhat horizontal aspect, a half dozen pitch pine tree stumps are within 10 feet of the current high water mark. There is a house at 12 feet vertical elevation and 75 feet horizontal distance from current mean high tide or 100 feet back from historic high tide. The sand of the dune is fine to medium sand with scant fines to fill voids (90% of the material between a #40 and a #16 screen), an 1/8 rod can be pushed to 5 feet with approximately 50 feet of downward force everywhere, wave heights are usually 0 to 2 feet from boat wakes and wind. At the waters edge is course sand with a few percent gravel this soon becomes (25 feet from high tide) a submerged sand mud mix that slopes from the mean high tide mark to approximately 2.5 feet of depth at high tide approximately 100 horizontal feet from mean high tide mark. The 1/8 inch rod can be pushed to 5 feet deep in the submerged bottom as well. The state of NJ limits stabilization to plantings. Bulk heads, geocloth, retaining walls within first 50 feet from the mean high water mark, and large rock isn't allowed but an "approved" replenishment sand is possible.

The restoration utility is two fold: 1.) restoring the earlier mean high tide mark allows greater latitude in stabilizing the dune near the house; 2.) two provide a buffer to resist erosion during a future storm and 3.) stabilize the dune against the 2 feet of ocean rise expected in the next 80 years. I am sorry I do not have hard quantifiables and just a qualitative site description. My question/ concern is where will I end up if I purchase 300 yards of course sand or a sand gravel road mix (if they (NJ) approve it). So it has a lot to do with the layman's angle of repose for submerged aggregates that on previous posts have been pore pressure/ friction and bouyancy of natural silica sand. I don't have the experience or judgement to foresee where I will end up. Any services contracted in NJ is profit driven.
 
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