20200237 Ver 1_5_Diffuse_Flow_20200214

Alamance Church Road Diffuse Flow Plan
The roadway improvements are located on Alamance Church between Martin Luther King Jr and the
Greensboro City limits. The NCDOT Stormwater Best Management Practices Toolbox was used to
minimize impacts from stormwater.
Impacts to buffers at site 1 and 2 mainly result from temporary impacts during retaining wall
installation. Stormwater pipe at site 1 will be replaced with the same size pipe. Site 2 stormwater pipe
will increase in size. A new stormwater pipe will be installed at site 3. The impact to the buffer is minimal
as there is almost no buffer in these areas. Stormwater flows completely bypass the buffer as the pipes
currently discharge directly into the unnamed tributary (UT) to South Buffalo Creek.
The surrounding area has a high percentage of development and existing impervious areas. Historically,
the UT was channelized to make room for this development and Alamance Church Road. The UT flows
between the roadway and a number of commercial buildings and parking lots. Riprap and maintained
herbaceous vegetation line the stream banks. Existing and proposed outfalls in this drainage area
discharge directly into the UT. Achieving diffuse flow for these pipes is not feasible due to the location of
the UT. A level spreader is not feasible due to space constraints and a preformed scour hole would lead
to additional impacts to jurisdictional waters as the riprap would have to be placed in the bed of the
channel. An offsite SCM is not feasible due to surrounding development and utility conflicts and the
proximity of the UT.
Impacts to buffers at site 4 include impacts from the culvert extension. Diffuse flow will be achieved
with the installation of a wet pond near the stream.