20181707 Ver 1_Summary of Buffer Impacts_20190201

II THE IINIYE UNIVERSITY
of NORTH CAROLINA
¢! CHAPEL HILL
SUMMARY OF BUFFER IMPACTS
UNC — Outdoor Education Center
Pond Retrofit Project
Permanent Impacts:
, EWELL
ENGINEERING CONSULTANTS, PC
Within the existing buffer around the open water area, there are a few aspects of the project that may
be considered permanent impacts. There is an existing concrete golf tee pad, which will be removed
and replaced by installation of a pad of the same size and type on the other side of the proposed
wetland. The existing golf tee is within Zone 1, but the future golf tee will be located within the area
currently within Zone 2 of the pond buffer. The existing pond outlet pipe will be replaced by larger
concrete pipes and concrete headwall and endwall structures. These structures are within the Zone 1
buffer area of either the pond or the downstream stream channel, but are necessary for the long-term
stability of the outlet and the control of the wetland water levels. A wooden deck/viewing platform is
proposed for installation within the wetland and a portion of the access ramp will be within the Zone 1
buffer for the existing pond. The purpose of the viewing platform is to educate groups about the
wetland and the impact is necessary for the access to the wetland. All of these impacts are quantified
on Buffer Impact Figure 1.
Temporary Impacts:
Most of the grading for the wetland restoration will occur within Zone 1 buffer areas for the existing
pond or the upstream channel. The grading will involve excavating for the forebay area and building
stable embankments around the wetland area. These impacts are necessary for retrofitting the pond as
a wetland. The Zone 1 buffer area which will become part of the restored wetland footprint (not
highlighted on Figure 1) totals 1317 square feet. All other impact quantities are listed on Figure 1. The
banks of the wetland will be reinforced with boulder steps and geoweb in the area of the incoming flows
from the forested area on the northwest side. There is no grading proposed to change the flow patterns
through the areas above the top of the existing slopes.
Additional fill will be placed to build up a raised pedestrian path along the downstream fairway. This is
not a change of use because the area is used for pedestrian traffic now and the intent is only to build up
an intentional pathway. Some of this open grassed area is within the Zone 2 buffer for the unnamed
tributary between the existing pond and Chapel Creek. The pedestrian path is to be located along the
tree line on the side of the fairway furthest from the stream, such that the fill extending within the Zone
2 buffer will be relatively limited, and the impacts will mostly be for construction access to build up the
path. A small Zone 1 area may have some small amount of fill placed for access to the viewing platform,
but most of the impact will only be for installation of silt fence around the platform. Grass cover similar
to existing conditions will be re-established in all of the disturbed areas of the fairway.
January 29, 2019

THE UNIVERSITY �JEWELL
III of NORTH CAROLINA //,�
"ENGINEERING CONSULTANTS, PC
a! CHAPEL HILL
Figure 2 shows the temporary impacts of the proposed stream restoration. All of the buffer areas will
either become part of the restored stream channel, inclusive of floodplain bench areas, or will be used
for construction access and staging. Some planting of trees outside of the stream area is also planned as
part of the project. Zone 1 and Zone 2 impact quantities are shown on Figure 2. Earlier considerations
of measures to direct flow from the existing pipe outlet (adjacent to the construction entrance from the
parking lot) were abandoned due to concerns about maintaining diffuse flow through the buffer. The
project does not include any modifications to the existing outlet near the parking lot.
January 29, 2019