20031 Barker Farm - Stormwater Management Report - 20031 Barker

Issue Dates Description
27 Nov 17 NCDEQ Review

Stormwater Management Report

For

20031 Barker Farm
Solar Power Generation Facility
Hope Mills, Cumberland County, North Carolina

(PIN: 0422513534)

Prepared by:

Ballentine Associates, P.A.
Consulting Engineers
221 Providence Road
Chapel Hill, NC 27514
[phone]

BA Project #: 117013.01

20031 Barker Farm Solar Energy System
27 Nov 17
_________________________________________________________________________________________________________________

Existing Conditions Description:

The 20031 Barker Farm, LLC Solar Energy System is located off Walter Canady Road in Hope Mills,
Cumberland County, North Carolina. The property PIN number is 0422513534. The project site contains
approximately 22.75 acres of agricultural fields and wooded lands. There are no structures located on
the site. The existing soils on the site include: Goldsboro loamy sand (GoA), Lynchburg sandy loam
(Ly), Pantego loam (Pg), Rains sandy loam (Ra), Torhunta and Lynn Haven soils (TR), Wagram loamy
sand (WaB) and Woodington loamy sand (Wo). The site is 1.4% hydrolic soil group (HSG) B, 8.3%
HSG B/D, 72.8% HSG A/D and 17.4% HSG A. The entire site drains toward the southwest direction
towards Run of Gallberry Swamp which is considered a jurisdictional stream. These jurisdictional
features include both intermittent and perennial classification. FIRM Panel 3720042200J indicates the
site does not lie within a special flood hazard area. The surface water classification for the site is C; Sw.
The site is located in the Lumber River basin. Project site Latitude and Longitude is 34.908071° and -
78.912788°.

Description of Proposed Project:

The proposed solar farm will consist of tracker solar panels, dual inverter/transformer areas and a chain
link fence along the perimeter of the array. The project will also include temporary laydown and
parking areas, and a permanent gravel driveway apron along Walter Canady Road The installation of the
solar panels themselves will not generally create significant land disturbance. The panels will be
mounted to racks, which are supported by a series of posts. The posts will be driven directly into the
existing ground without excavation or land disturbance and the existing ground cover will be allowed to
remain to the extent possible. Overall, approximately 17.5 acres of land will be disturbed by
construction; this is our entire project limits. The project areas true disturbance is caused by clearing and
grubbing, rubber tire vehicles accessing the site to distribute and install above grade material and a
dozen or so small trenches (2’ wide, 36” deep) for wiring the array. The rack posts are mechanically
driven directly into the ground. The entire disturbed area will be protected by silt fence with silt fence
outlets. No change in drainage patterns (site drainage remains as sheet flow) or additional ponding of
water will occur as a result of this project. At the completion of construction, the entire site will be
seeded to create a good stand of grass.

Erosion control measures for this site have been designed in accordance with the NCDENR Erosion and
Sediment Control Planning and Design Manual (Revised 5/13).

Stormwater Design:
At the completion of construction, the entire site will be seeded with a permanent grass seed to create a
good stand of grass. Since the panels are supported above the ground surface, grass is allowed to grow
under the panels. Rainwater will sheet flow off the panels and onto the grass. The panels are therefore
not considered to be impervious cover, as confirmed in the attached email from Julie Ventaloro with
NCDENR-DQW, dated May 17, 2013. A copy of this letter is included in the attached exhibits. The
proposed drive, inverter pads and rack posts will contribute a total of 29,350 sf of impervious surface.
As shown in the 20031 Barker Farm Solar Power Generation Facility - Impervious Percentage
Calculations included in in Appendix B, the post development impervious cover will be 2.96% of the
total project area. Therefore, this project is considered Low Density and does not alter the pre-
development stormwater runoff characteristics of the site.
20031 Barker Farm Solar Energy System
27 Nov 17
_________________________________________________________________________________________________________________

List of Exhibits:

· Maps
o NRCS Soils Map
o NRCS Hydrologic Soil Group Map
o USDA Soils Map - Hardbound
o USGS Topo Map
o FIRM Panel 3720042200J
o Aerial Photo

· Calculations
o 20031 Barker Farm Site Impervious Calcs
o NCDENR Impervious Opinion Email from Julie Ventaloro

9
Custom Soil Resource Report
Soil Map
3864700386480038649003865000386510038652003864700386480038649003865000386510038652003865300689900 690000 690100 690200 690300 690400 690500 690600 690700 690800
689900 690000 690100 690200 690300 690400 690500 690600 690700 690800
34° 54' 44'' N 78° 55' 17'' W34° 54' 44'' N78° 54' 39'' W34° 54' 23'' N
78° 55' 17'' W34° 54' 23'' N
78° 54' 39'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,510 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Cumberland County, North Carolina
Survey Area Data: Version 17, Sep 19, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Feb 14, 2011—Mar 3,
2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
10
Map Unit Legend
Cumberland County, North Carolina (NC051)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
GoA Goldsboro loamy sand, 0 to 2
percent slopes, Southern
Coastal Plain
0.9 1.4%
Ly Lynchburg sandy loam, 0 to 2
percent slopes
3.6 5.5%
Pg Pantego loam 1.8 2.8%
Ra Rains sandy loam, 0 to 2
percent slopes
19.9 30.8%
TR Torhunta and Lynn Haven soils 23.2 35.9%
WaB Wagram loamy sand, 0 to 6
percent slopes
11.2 17.4%
Wo Woodington loamy sand 4.0 6.1%
Totals for Area of Interest 64.5 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
Custom Soil Resource Report
11
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
Custom Soil Resource Report
12
Hydrologic Soil Group—Cumberland County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/26/2017
Page 1 of 43864700386480038649003865000386510038652003864700386480038649003865000386510038652003865300689900690000690100690200690300690400690500690600690700690800
689900 690000 690100 690200 690300 690400 690500 690600 690700 690800
34° 54' 44'' N 78° 55' 17'' W34° 54' 44'' N78° 54' 39'' W34° 54' 23'' N
78° 55' 17'' W34° 54' 23'' N
78° 54' 39'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,510 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Cumberland County, North Carolina
Survey Area Data: Version 17, Sep 19, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Feb 14, 2011—Mar 3,
2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Hydrologic Soil Group—Cumberland County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/26/2017
Page 2 of 4
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit — Cumberland County, North Carolina (NC051)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
GoA Goldsboro loamy sand,
0 to 2 percent slopes,
Southern Coastal
Plain
B 0.9 1.4%
Ly Lynchburg sandy loam,
0 to 2 percent slopes
B/D 3.6 5.5%
Pg Pantego loam B/D 1.8 2.8%
Ra Rains sandy loam, 0 to
2 percent slopes
A/D 19.9 30.8%
TR Torhunta and Lynn
Haven soils
A/D 23.2 35.9%
WaB Wagram loamy sand, 0
to 6 percent slopes
A 11.2 17.4%
Wo Woodington loamy sand A/D 4.0 6.1%
Totals for Area of Interest 64.5 100.0%
Hydrologic Soil Group—Cumberland County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/26/2017
Page 3 of 4
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Cumberland County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/26/2017
Page 4 of 4
PROPOSEDPROJECT LIMITS
Area (sf) Area (ac) % of Total
75,218 1.727 7.59%
911,094 20.916 91.93%
4,799 0.110 0.48%
0 0.000 0.00%
4,799 0.110 0.48%
991,111 22.753 100.00%
Area (sf) Area (ac) % of Total
75,218 1.727 7.59%
886,543 20.352 89.45%
4,799 0.110 0.48%
0 0.000 0.00%
24,409 0.560 2.46%
# of Pads Area/Pad (sf)
0 100 0 0.000 0.000%
# of Inverters Area/Inverter
(sf)
1 120 120 0.003 0.01%
Posts/Rack # of Racks Area/Post (in2)
5 90 2.7 8 0.000 0.00%
8 93 2.7 14 0.000 0.00%
29,350 0.673 2.96%
991,111 22.752 100.00%
Total Site Area =
Proposed Drives (Gravel/Conc./Asphalt)
(Assumes entire graded area)
Proposed Impervious=
Wooded Areas
Impervious
Pervious
Impervious
Pervious
Agricultural Fields/Lawns
Switchgear Pads
Existing Structures to Remain
Agricultural Fields/Lawns
Inverter Total
Rack Posts Total
Inverter Areas
Rack Posts
Inverter Total
Existing Drives to Remain
Existing Impervious=
20031 Barker Farm Solar Power Generation Facility - Impervious Calculation
Existing Conditions
Drives (Gravel/Conc./Asphalt)
Structures
Total Site Area =
Proposed Conditions
Wooded Areas
20031 Barker Farm Site Impervious Calcs
Impervious Calcs 7/26/2017
1
George Retschle
From:Brent Niemann <[e-mail]>
Sent:Friday, May 31, 2013 4:33 PM
To:Cameron Weaver; Carol Miller
Cc:George Retschle
Subject:Fwd: Fixed-tilt rack mounted photovoltaic solar panels
And here is Julie's response.........

Brent Niemann, PE
Civil Engineer
Right-click here to download pictures. To help protect your privacy, Outlook prevented automatic download of this picture from the Internet.
1119 U.S. Hwy. 15-501 South
Chapel Hill, NC 27517
O: 919.960.6015 x133
M: 919.268.7137
www.stratasolar.com

---------- Forwarded message ----------
From: Ventaloro, Julie <[e-mail]>
Date: Fri, May 17, 2013 at 10:16 AM
Subject: RE: Fixed-tilt rack mounted photovoltaic solar panels
To: Brent Niemann <[e-mail]>
Cc: Michael Harvey <[e-mail]>, "Joshua Crumpler PE, LEED AP"
<[e-mail]>, "Bennett, Bradley" <[e-mail]>, Cullen Morris
<[e-mail]>

Hi Brent,

Based on the information you provided, I would say that your solar panels could be considered pervious for purposes of 
calculating percent imperviousness for compliance with the Water Supply or Phase 2 stormwater rules.  I conferred with 
Mike Randall who coordinates the state’s Phase 2 program, and he agrees.  As you described, the concrete pads and 
posts would be considered impervious.    If you will be using heavy machinery that compacts the soil and significantly 
reduces infiltration, you may also need to consider those areas impervious.

Please let me know if you have further questions.

Julie Ventaloro
2
Coordinator, Water Supply Watershed Protection Program
NC Division of Water Quality
Wetlands & Stormwater Branch
1617 Mail Service Center, Raleigh, NC  27699‐1617
Phone:  (919) 807‐6370    Fax:  (919) 807‐6494
Website: http://watersupplywatershed.nc.gov

E‐mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be disclosed to third 
parties.

From: Brent Niemann [mailto:[e-mail]]
Sent: Wednesday, May 15, 2013 12:16 PM
To: Ventaloro, Julie
Cc: Michael Harvey; Joshua Crumpler PE, LEED AP; Bennett, Bradley; Cullen Morris
Subject: Fixed-tilt rack mounted photovoltaic solar panels

Good morning Julie.
As a follow up to our conversation, I have attached some pertinent information for your review.

We met with Michael Harvey at Orange County last week regarding an upcoming project we have received
zoning approval for & are moving forward with construction drawings. Based on the information provided in
this memo, your conversation with Terry Hackett was specific to "tracker" solar systems.

We install fixed-tilt rack mounted PV panels facing south, which do not rotate. Our racks provide a minimum
of 30" of clearance at the front & are tilted at 20-25 degrees from horizontal, making them less than 8' tall at the
back. Each rack contains between 24-38 panels in portrait, depending on the equipment specified for the
farm. This makes each rack between 45'-65' long. There is approximately a 1" gap between each panel on each
rack (horizontal gap & vertical gap). Also, there is a minimum 6" gap between racks horizontally (sometimes
more to accommodate site access). The rows of racks are spaced between 9'-20', to provide access & prevent
racks from shading each other. I have attached some pictures to help with my descriptions. Also, here is a link
to our website and you can look through various project photos (http://www.stratasolar.com/utility/utility-
project-spotlight/).
We have permitted over a dozen farms throughout the state (mostly through NCDENR regional offices) & our
rack mounted panels have never been considered impervious. The only proposed impervious surfaces we install
are the driven posts (cross sectional area is about 2.5 sq, in. each, about 3,000-4,000 per site based on soil
conditions & system size) and pre-cast concrete pads for inverter/transformer equipment (about 100 sf each, 6-
10 per site). Overall the impervious calculations for our farm placed in an agricultural field, are less than
3
0.5%. We utilize logging mats during construction to provide access in wet, rutted areas. Following
construction, we remove the mats, regrade, seed & stabilize.

Based on this information, can you provide us your interpretation of how you would consider our solar farms
from a pervious/impervious standpoint? Please feel free to call or email me if you have any questions or require
additional information.
Thanks
Brent

Brent Niemann, PE
Civil Engineer
Right-click here to download pictures. To help protect your privacy, Outlook prevented automatic download of this picture from the Internet.
1119 U.S. Hwy. 15-501 South
Chapel Hill, NC 27517
O: 919.960.6015 x133
M: 919.268.7137
www.stratasolar.com