Rone Creek Subdivision - 229-001-STORMWATER-SUMMARY

SUPPORTING DOCUMENTS
FOR
RONE CREEK STATION
RESIDENTIAL SUBDIVISION
WAXHAW, NC
114111
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3/28/19
PREPARED BY
R.D. DAVIS ENGINEERING, PLLC
P.O. BOX 470085, CHARLOTTE, NC 28247

STORM WATER DESIGN SUMMARY
The Rone Creek subdivision proposes to maintain all impervious surfaces at 24% or less of the
total project area outside of the existing right of way. This percentage will be considered low
density per the MS4 Stormwater Program. The primary treatment device will be dispersed flow
from houses and roads. The dispersed flow consists of vegetated areas (primarily grass) directly
adjacent to impervious surfaces, such as houses, drives, sidewalks and roads. As indicated on
the accompanying plans, the lots around the perimeter of the project are directly adjacent to
natural areas that consist of well -established vegetation (primarily trees). Stormwater runoff
will be diffused through the grass vegetation then enter these areas for further treatment. In
other areas where storm drain pipes are proposed, RDD limited to the maximum extent
possible to increase the quantity of pipes to lower the concentrated quantity of runoff. The
pipe outlets have been carefully analyzed to maximize the diffusion into natural areas after
exiting the pipe. Also, vegetated swales have been designed to provide a "disconnected" flow
regime prior to entering the piped system.
All stream crossings for utilities (sewer) are designed to be bored under the stream flowline
with zero disturbance to streams below the normal high water line. We have had a stream and
wetland study performed by Len Rindner of Wetlands and Environmental Planning Group, PLLC
and it is attached. It should be noted that the stream buffer shown on stream D is determined
by the USGS and NRCS maps per ordinance and not by this determination. (the stream was
evaluated in wet season and exhibited base flow not normally present in summer). Union
County Stormwater has required the establishment of reserved low land hardwood
preservation area as mitigation for the utility location within the buffer area.