20200564 Ver 1_JNX PCN - Cumulative Impacts Discussion_20200423

G3c. Although this project is specifically geared toward alleviation of flooding and ponding water, the
implementation of a closed drainage network may facilitate future development at the airport. Related
potential future development could include parking facilities over the pipe network. The intent of the
cumulative impact assessment process is to determine the potential for growth and land use changes,
typically on the scale of new subdivisions, shopping centers, etc. In the case of this project, the
development would be limited to the potential conversion of approximately 0.5 acres of grass lawn to
paved parking.
The conversion of grass to paved parking over 0.5 acres could result in a discharge increase of 1.8 cfs
(based on "C" factors of 0.3 (grass) and 0.9 (pavement) and an intensity of 6 in/hr). This increase is
negligible compared to the ultimate system outfall of approximately 100 cfs.
Any future projects would be pursuant to the Town of Smithfield stormwater ordinance. The purpose of
the ordinance is to:
"establish minimum criteria to control and minimize quantitative and qualitative
impacts of stormwater runoff from development within the Town of Smithfield, a
nutrient management program for new development in accordance with 15A
NCAC 2B.0235 Neuse River Basin Nutrient Sensitive Waters Management
Strategy: Basinwide Stormwater Requirements."
Finally, there is a project which is currently under construction at the airport, but it is not related to this
drainage project. The intent of the other project is to construct a new Fixed Based Operator,
Maintenance Facility, and expanded parking area. The outfall from the project under construction will
discharge to the proposed system of this project but is not a factor in the sizing of the proposed 54" pipe
and is not linked to this project in any other way.