20200516 Ver 1_SLP-Comment Response_20200527

Equinox and S20 Design and Engineering
Silverline Park Boat Ramp, Asheville NC
Comment Response - 05/27/2020
Amor
1
NC Wildlife Resources
Comment
1
On Sheet ww1.0, Construction Sequence, Item #14 calls for installation of a coffer dam around
the base of the ramp if water level is higher than the ordinary high-water elevation at the time of
construction. I do not see that the OHWM elevation is called out anywhere on the plan
Commision drawings? I would expect the OHWM would be well above the footing elevation. How do they
plan to pour the end footing in place and in the dry (shown on Sheet 5.0, detail 3/D-1) with the
river level is below that mark?
1) The OHW line has been called out in the drawings, in planview, profile, and in the notes. OHW Elevation is 1945.1'.
2) Installation of the boat ramp and boulder toe footer will be completed in the dry using a coffer dam and silt basin
combo. This detail has been provided and elaborated on page WW-6.0.
Is this ramp intended only for carry -down canoe & kayak launching? If the ramp does not extend
to the river bed, it will not be well suited for launching and retrieving boats (Jon boats, McKenzie
NC Wildlife Resources
boats, etc.) with trailers. There could be attempts to launch these types of boats at this ramp.
1) This ramp is for all boats, and therefore does key in at the riverbed elevation at 1942.84 . This has been clarified on the
2
With a ramp that ends abruptly at the water edge, boaters may try to back a trailer too far, and
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Commision
could get it hung up on the boulder line across the end. This could result in damage to the trailer,
planset in planview, profile, and the notes.
boat, river bed and/or ramp structure. Suggest that the designer consider a push slab for the end
of ramp section or installing bollards at the top of ramp to restrict vehicle access.
1) LOD has been adjusted to accomidate the space required for the coffer dam installation and footing construction. This
is represented in planview. An estimate of the area necessary for dry work encompassed by the coffer dam and including
On Sheet ww2.0, the LOD line runs through the line of boulders to be placed over the end
the silt basin dewatering system has been calculated based on standard detail calculations and displayed on plans - this is
NC Wildlife Resources
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footing. If a coffer dam is to be installed for the footing construction, it seems that this line
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subject to change once decided if the stone toe construction will or will not be included, but for now it has been assumed
Commision
should run several feet to the outside of the footing and boulder line.
that it will and that space has also been taken into account. LOD area allows for 10' dry space outward from permanent
constructed features, space for the temporary stilling basins and dewatering methods, and an addition 4' outward for the
actual coffer dams.
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On Sheet ww5.0, notes for Placing Concrete should mention that no wet concrete is to come in
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Commision
contact with surface water.
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1) Suggested notes has been added on sheet WW-5.0, Notes: Placing Concrete: (A) General.
V IF
1) Detail of cofferdam and silt basin has been provided on page WW-6.0 AND WW-7.0. The coffer dam detail is a typical
S20 detail that has multiple options of dam composition that can be selected. The silt basin detail had been altered to
Construction sequencing details for boat ramp notes installation of coffer dam. Will need
meet design requirements from NCDOT Erosion &Sediment control manual. (4.8.3 Stilling Basin, pg. 4-197)
5 US Army Corps of Engineers
details submitted for the coffer dam and if below OHWM then will need to include in the PCN as
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(https://connect.ncdot.gov/resources/roadside/SoilWaterpocuments/Erosion%20and%2OSediment%2OControl%2ODesig
temporary open water impact.
n%20and%20Construction%20Manual.pdf ) and had been noted in General Note 8) on WW-6.0. General Notes 9) and 10)
specifically.
Suggested impact noted was a result of the triangle resolution of the surface created in AutoCAD. No fill will take place
On Plan Sheet L0.4, there's a wetland impact that appears unaccounted for (see red circle on
6 US Army Corps of Engineers
attached plan sheet). This will need to be included in the PCN if not already.
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beyond the LOD as revised to accommodate the Coffer Dam. The sheet L.0.4 has been adjusted to reflect more
accurately the fill locations.
Please see the attached exhibit highlighting the cubic yards of impact below the OHWM. linear feet from end of boat
,For the boat ramp, will need linear footage of impact to river bank as well as cubic yards of
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material excavated and/or filled below OHWM. Also, will need to provide information as to why
ramp to the bank is 2 LF. The ramp is designed to be wider than 20-feet to accommodate multiple uses and to reduce
7 US Army Corps of Engineers
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congestion. As a major entry into the river for the Woodfin blueway, the ramp was designed to be 30-feet. At 30-feet,
ramp will be wider than 20-feet and please address what type of/expected boats will be using the
the ramp will have a 16-foot width marked for trailers and a 14-foot width striped off for no trailers. This section will be
ramp. This will need to be included in the PCN.
for non -motorized blueway users.
8 US Army Corps of Engineers
I will process the PCN under NWP #42 which should cover the wetland fill and the boat ramp
OK
5 trees will be removed along the French Broad River as identified on sheet L1.0 to lower the berm. Plantings have been
9 US Army Corps of Engineers
Please clarify if any trees/number of trees that will be removed along the French Broad River.
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added to the bank, see sheet L13.1
Will the proposed boardwalk be constructed without any temporary impacts to the existing
Yes; the road that is proposed to cross the wetland will be contructyed first, then we will use that road in addition to
10 NC Division of Water Resources
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wetland, particularly with regard to construction equipment and access. [15A NCAC 02H .0502]
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edges of the wetland
Has any consideration been given to a push in place concrete slab for the end of the ramp? The
use of wet concrete below the OHWM, even with a coffer dam, leaves the river highly vulnerable
A discussion about a push in place concrete slab has not been had with the team, but we can certainly have that
11 NC Division of Water Resources
Ito accidental discharges of wet concrete, which can significantly affect pH and be toxic to aquatic
Considering
conversation about the feasibility based on design parameters.
life. [15A NCAC 02B .0200]