SW3190802_Revised DEQ Calculation Package_11-11-2019_11/12/2019

STORMWATER CALCULATIONS
FOR:
TRINITY ELECTRIC SUBSTATION
MONROE (UNION COUNTY, NC
PREPARED FOR:
UNION POWER COOPERATIVE
04�i
�o
:a SEAL-
AA1 AAL
#070717
JURY 2019
REVISED NOVEMBER, 2019
Prepared by:
D
ENGINEERING
Fort Mill, SC

Trinity Substation Stormwater Management Report
STORMWATER MANAGEMENT REPORT
Project: Trinity Electric Substation
PIKE Job Number: 070717
Location: PID #04-132-016B
Date Prepared: July 2019
Owner: Union Power Cooperative
Address: 1525 North Rocky River Road
Monroe, NC 28110
Engineer: PIKE Engineering
Address: 123 North White Street
Fort Mill, SC 28110
Phone: [phone]
Report Prepared By:
David Sherrill, P.E.
Report Reviewed By:
Nathan Bass, PLA
Date: July 15, 2019
Date: July 16. 2019
Page ii

07117_Trinity Electric Substation Level Spreader -Filter Strip (LS_FS)
Design Summary
Stormwater calculations are required to analyze a proposed new development for its impacts on peak
flows and volumes. Stormwater programs in North Carolina typically include provisions to control and
treat a certain volume of stormwater runoff and/or provisions to control the peak stormwater discharge
rate. The primary method that is used to determine peak runoff rate for North Carolina's stormwater
programs is the Rational Method. The Rational equation is given as:
Q = C * I * A
Where: Q = Estimated design discharge (cfs)
C = Composite runoff coefficient (unitless) for the watershed
I = Rainfall intensity (in/hr) for the designated design storm in the geographic
region of interest
A = Watershed area (ac)
The composite runoff coefficient reflects the surface characteristics of the contributing watershed. The
range of runoff coefficient values varies from 0 —1.0, with higher values corresponding to greater runoff
rate potential. The runoff coefficient is determined by estimating the area of different land uses within
each drainage area. Table 3-2 presents values of runoff coefficients for various pervious and impervious
surfaces. The Division believes that the Rational Method is most applicable to drainage areas
approximately 20 acres or less.
Unimproved Areas
Asphalt
Concrete
Rational Runoff Coefficients, C
0.35
Lawns, sandy soil, average (2-7%)
Lawns, sandy soil, steep (>7%)
Lawns, heavy soil, steep (>7%)
Wooded areas
Pasture (mixed vegetation)
Pasture (mostly grass)
0.95
0.95
0.15
0.20
0.30
0.15
0.45
0.60
The Level Spreader Lip is calculated by determining the Peak Flow with a design intensity of 0.75 in./hr.
multiplied by 10 feet per cfs to determine the minimum required lip of the spreader.
For Channel 1, with an area of 1.2 acres, Q.75 = 0.70 x 0.75 x 1.2 = 0.63 cfs
For Channel 2, with an area of 1.65 acres, Q.75 = 0.70 x 0.75 x 1.65 = 0.86 cfs
For 12" RCP discharge pipe, with an area of 0.5 ac, Q10 = 2.4 cfs (see Storm calculation, following pages)
Total Peak Flow = 0.63 + 0.86 + 2.4 = 3.89 cfs x 10 ft/cfs = 34.9 feet
Length of Level Spreader provided = 55 ft. > 34.9 ft. therefore LS length OK

CHARLOTTE-MECKLENBURG STORM WATER DESIGN MANUAL
Table 2-2
Rainfall Intensities
-
Charlotte, North
Carolina (continued)
Time
Recurrence interval (years)
Hours
Minutes
2
5
10 25
50
100
1
60
1.45
1.98
2.36 2.76
3.05
3.34
2
120
0.88
1.21
1.45 1.70
1.89
2.06
3
180
0.65
0.90
1.07 1.25
1.40
1.52
6
360
0.38
0.53
0.62 0.73
0.82
0.89
12
720
0.22
0.31
0.36 0.42
0.47
0.51
24
1440
0.13
0.18
0.20 0.24
0.27
0.29
P24 (inches - in.)
3.12
4.32
4.80 5.76
6.48
6.96
2.4 RATIONAL METHOD
2.4.1 Introduction
When using the rational method some precautions should be considered.
In determining the C value (land use) for the drainage area, hydrologic analysis should
take into account future land use changes. Drainage facilities shall be designed for future
land use conditions as specified in the County and City Land Use Plans and Zoning Maps
(or existing land use, whichever generates the higher runoff rate).
Since the rational method uses a composite C value for the entire drainage area, if the
distribution of land uses within the drainage basin will affect the results of hydrologic
analysis, then the basin should be divided into two or more sub -drainage basins for
analysis.
• The charts, graphs, and tables included in this section are given to assist the engineer in
applying the rational method. The engineer should use good engineering judgment in
applying these design aids and should make appropriate adjustments when specific site
characteristics dictate that these adjustments are appropriate.
2.4.2 Runoff Equation
The rational formula estimates the peak rate of runoff at any location in a watershed as a function
of the drainage area, runoff coefficient, frequency factor, and mean rainfall intensity for a
duration equal to the time of concentration (the time required for water to flow from the most
remote point of the basin to the location being analyzed). The rational formula is expressed as
follows:
Q = CfCIA (2.2)
Where: Q = maximum rate of runoff (cubic feet/second - cfs)
C = runoff coefficient representing a ratio of runoff to rainfall
I = average rainfall intensity for a duration equal to the time of
concentration (in/hr)
2-6

\O��E W AT F9�G
NCDENR
> ti
Y
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION
APPLICATION FORM
LEVEL SPREADER - VEGETATED FILTER STRIP (LS-VFS) SUPPLEMENT
This form must be completely filled out, printed, initialed, and submitted.
I. PROJECT INFORMATION
Project name
Trinity Electric Substation
Contact name
Pie Engineering
Phone number
[phone]
Date
November 1, 2019
Drainage area number
LS/FS-01
II. DESIGN INFORMATION
The purpose of the LS-VFS
SW Rule: Diffuse flow at the end of a swale discharging to SA waters
Stormwater enters LS-VFS from
A BMP
Type of VFS
Engineered filter strip (graded & sodded, slope < 8%)
Swales diffused by Level Spreader have 500 I.f. additional vegetative conveyance beyond
Explanation of any "Other" responses above
filter strip
If Stormwater Enters the LS-VFS from the Drainage Area
Drainage area
ffz Do not complete this section of the form.
Impervious surface area
ffz Do not complete this section of the form.
Percent impervious
% Do not complete this section of the form.
Rational C coefficient
Do not complete this section of the form.
Peak flow from the 1 in/hr storm
cis Do not complete this section of the form.
Time of concentration
min Do not complete this section of the form.
Rainfall intensity, 10-yr storm
in/hr Do not complete this section of the form.
Peak flow from the 10-yr storm
cfs Do not complete this section of the form.
Design storm
Pick one:
Maximum amount of flow directed to the LS-VFS
cis Do not complete this section of the form.
Is a flow bypass system going to be used?
(Y or N) Do not complete this section of the form.
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from a BMP
Type of BMP
Other: Explained below
Peak discharge from the BMP during the design storm
1.9 cfs
Peak discharge from the BMP during the 10-year storm
7.3 cfs
Maximum capacity of a 100-foot long LS-VFS
10 cis
Peak flow directed to the LS-VFS
3.2 cfs
Is a flow bypass system going to be used?
Y (Y or N)
Explanation of any "Other" responses above
stormwater enters the level spreader from vegetated swale discharge and SPCC pipe
discharge
Form SW401 - LS-VFS - 29June2012 - Rev.10 page 1 of 3

LS-VFS Design
Forebay surface area
1,100
sq ft No forebay is required.
Depth of forebay at stormwater entry point
9
in
Depth of forebay at stormwater exit point
6
in Depth is appropriate.
Feet of level lip needed per cfs
10
ft/cfs
Computed minimum length of the level lip needed
32
ft
Length of level lip provided
63
ft
Width of VFS
30
ft
Elevation at downslope base of level lip
617.20
fmsl
Elevation at the end of the VFS that is farthest from the LS
617.00
fmsl
Slope (from level lip to the end of the VFS)
0.67
%
Are any draws present in the VFS?
N
(Y or N) OK
Is there a collector swale at the end of the VFS?
Y
(Y or N)
Bypass System Design (if applicable)
Is a bypass system provided?
Is there an engineered flow splitting device?
Dimensions of the channel (see diagram below):
M
B
W
y (flow depth for 10-year storm)
freeboard (during the 10-year storm)
Peak velocity in the channel during the 10-yr storm
Channel lining material
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Explanation of any "Other" responses above
N (Y or N)
N (Y or N)
ft
ft
ft
ft
ft
ft/sec
Pick one:
(Y or N)
(Y or N)
W
i B i
Form SW401 - LS-VFS - 29June2012 - Rev.10 page 2 of 3

III. REQUIRED ITEMS CHECKLIST
EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the
following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been
met, attach justification.
Requried Item:
1. Plans (V - 50' or larger) of the entire site showing:
- Design at ultimate build -out,
Off -site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Forebay (if applicable),
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW), and
Boundaries of drainage easement.
2. Plan details (V = 30' or larger) for the level spreader showing:
- Forebay (if applicable),
High flow bypass system,
One foot topo lines between the level lip and top of stream bank,
Proposed drainage easement, and
Design at ultimate build -out.
3. Section view of the level spreader (1" = 20' or larger) showing:
- Underdrain system (if applicable),
Level lip,
Upslope channel, and
Downslope filter fabric.
4. Plan details of the flow splitting device and supporting calculations (if applicable)
5. A construction sequence that shows how the level spreader will be protected from
sediment until the entire drainage area is stabilized.
6. If a non -engineered VFS is being used, then provide a photograph of the VFS showing
that no draws are present.
7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
Initials Page or plan sheet number and any notes:
See proposed Level Spreader -Filter Strip on the Erosion Control sheet
7 and Grading Plan sheet 8, and on detail sheet 13. (DDS)
Forebay has been provided although not required. Bypass is not
required on this system. No stream near project site. Proposed 10'
stormwater maintenance easement is shown on Site Plan sheet 3,
Erosion Control Plan sheet 7 and Grading Plan sheet 8. (DDS)
Section view and level lip are shown on detail sheet 13. Underdrain is
not required for this system. (DDS)
See attached plans and supporting calculations.
(DDS)
Construction Sequence is shown as detail 11-01 on sheet 11.
Sediment protection for the Level Spreader is shown on Erosion
Control Plan sheet 7. (DDS)
In this instance, the site and LS-FS area have been surveyed at 1-foot
contour intervals which more accurately and clearly depicts the
absence of any draw better than any photgraph could. (DDS)
Attached (DDS)
Original to be mailed separately by the responsible party.
(DDS)
Form SW401 - LS-VFS - 29June2012 - Rev.10 page 3 of 3

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Filter Strip, Restored Riparian Buffer and Level Spreader
Operation and Maintenance Agreement
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
Important maintenance procedures:
— Immediately after the filter strip is established, any newly planted vegetation
will be watered twice weekly if needed until the plants become established
(commonly six weeks).
— Once a year, the filter strip will be reseeded to maintain a dense growth of
vegetation
— Stable groundcover will be maintained in the drainage area to reduce the
sediment load to the vegetation.
— Two to three times a year, grass filter strips will be mowed and the clippings
harvested to promote the growth of thick vegetation with optimum pollutant
removal efficiency. Turf grass should not be cut shorter than 3 to 5 inches and
may be allowed to grow as tall as 12 inches depending on aesthetic requirements
(NIPC, 1993). Forested filter strips do not require this type of maintenance.
— Once a year, the soil will be aerated if necessary.
— Once a year, soil pH will be tested and lime will be added if necessary.
After the filter strip is established, it will be inspected quarterly and within 24 hours
after every storm event greater than 1.0 inch (or 1.5 inches if in a Coastal County).
Records of operation and maintenance will be kept in a known set location and will be
available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element:
Potential problem:
How I will remediate the problem:
The entire filter strip
Trash/debris is present.
Remove the trash/debris.
system
The flow splitter device
The flow splitter device is
Unclog the conveyance and dispose
(if applicable)
clogged.
of any sediment off -site.
The flow splitter device is
Make any necessary repairs or
damaged.
replace if damage is too large for
repair.
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 1 of 3

BMP element:
Potential problem:
How I will remediate the problem:
The swale and the level
The swale is clogged with
Remove the sediment and dispose
lip
sediment.
of it off -site.
The level lip is cracked,
Repair or replace lip.
settled, undercut, eroded or
otherwise damaged.
There is erosion around the
Regrade the soil to create a berm
end of the level spreader that
that is higher than the level lip, and
shows stormwater has
then plant a ground cover and
bypassed it.
water until it is established. Provide
lime and a one-time fertilizer
application.
Trees or shrubs have begun
Remove them.
to grow on the swale or just
downslo e of the level lip.
The bypass channel
Areas of bare soil and/or
Regrade the soil if necessary to
erosive gullies have formed.
remove the gully, and then
reestablish proper erosion control.
Turf reinforcement is
Study the site to see if a larger
damaged or ripap is rolling
bypass channel is needed (enlarge if
downhill.
necessary). After this, reestablish
the erosion control material.
The filter strip
Grass is too short or too long
Maintain grass at a height of
(if applicable).
approximately three to six inches.
Areas of bare soil and/or
Regrade the soil if necessary to
erosive gullies have formed.
remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.
Sediment is building up on
Remove the sediment and
the filter strip.
restabilize the soil with vegetation if
necessary. Provide lime and a one-
time fertilizer application.
Plants are desiccated.
Provide additional irrigation and
fertilizer as needed.
Plants are dead, diseased or
Determine the source of the
dying.
problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application.
Nuisance vegetation is
Remove vegetation by hand if
choking out desirable species.
possible. If pesticide is used, do not
allow it to get into the receiving
water.
The receiving water
Erosion or other signs of
Contact the NC Division of Water
damage have occurred at the
Quality local Regional Office, or the
outlet.
401 Oversight Unit at 919-733-1786.
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 2 Of 3

Permit Number:
(to be provided by DWQ)
I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Project name: Trinity Electric Substation
BMP drainage area number: Level Spreader -Filter Strip - 01
Print name: Matt Baucom_ RE
Title: Plant Development Engineer, Union Power Cooperative
Address: 1525 North Rocky River Road, Monroe, NC 28110
Phone: [phone] ext. 3141
Signature:
Date:
Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.
I, , a Notary Public for the State of
County of , do hereby certify that
personally appeared before me this
day of 1 , and acknowledge the due execution of the
forgoing filter strip, riparian buffer, and/or level spreader maintenance requirements.
Witness my hand and official seal,
SEAL
My commission expires
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 Of 3

EPA Spill Prevention Control & Countermeasures Plan (SPCC)
Containment Pipe Calculations
The following calculations explain how the proposed 30" RCP pipes intended for oil containment were
designed to contain not only the maximum capacity of oil for any single vessel failure, but also for
simultaneous above -ground runoff from a 25-year storm event as well.
The calculation titled Oil Storage computes the depth of 5,000 gallons of oil within a determined length
of RCP pipe at a certain diameter. The largest amount of oil contained on -site within any single piece of
electrical equipment is 5,000 gallons. The total length of RCP pipe is 330 I.f. In the event of an oil spill,
the maximum depth of oil contained in the SPCC pipe system will be 11.67" or 11.8'. The proposed
Oil/Water Separator structure will contain oil via the specific weight of the lighter liquid while allowing
water to continue to pass through the outfall pipe.
The attached HydroCAD calculation shows the depth stormwater will rise within the SPCC pipe system
during a 25-year storm event. The predetermined tailwater depth was set at 11.9' above the pipe invert
of 619.5 to account for 5,000 gallons of oil. The resulting calculations show that the peak flow elevation
is at 623.27, which is 1.62' lower than the ridgeline shown on the grading plan. Therefore oil will be
contained within the SPCC pipes and not overtop the above -ground ridgeline.
The attached HydraFlow Storm Sewers calculation shows that the 12" RCP discharge pipe has been
adequately sized for 10-year and 25-year storm events. The rip -rap outlet calculation has also been
provided to show the required design specifications for proper energy dissipation.

TRINITY OIL STORAGE SYSTEM VOLUMES
Pipe Dia.
30 in
Pipe Length
330 ft
*Note: for 5,000 gal, depth = 11.67"
4420 GAL
Number Of CB
Catch Basin Round
Diameter
48 in
Catch Basin Box(s)
4
Width Length
48in 48in
Elev.
(inches)
Pipe
(cubic ft)
Catch Basin Round
(cubic ft)
Catch Basin Box(s)
(cubic ft)
Total Storage
(cubic ft)
Total Storage
(gallons)
1
110.00
1.05
5.33
115.33
862.75
2
46.38
2.09
10.67
57.04
426.72
3
84.31
3.14
16.00
100.31
750.33
4
128.40
4.19
21.33
149.73
1120.06
5
177.46
5.24
26.67
204.13
1526.97
6
230.64
6.28
32.00
262.64
1964.65
7
287.26
7.33
37.33
324.59
2428.12
8
346.78
8.38
42.67
389.45
2913.25
9
408.72
9.42
48.00
456.72
3416.51
10
472.67
10.47
53.33
526.00
3934.75
11
538.24
11.52
58.67
596.90
4465.14
12
605.08
12.57
64.00
669.08
5005.02
13
672.85
13.61
69.33
742.18
5551.91
14
741.24
14.66
74.67
815.91
6103.41
15
809.94
15.71
80.00
889.94
6657.21
16
878.64
16.76
85.33
963.97
7211.01
17
947.03
17.80
90.67
1037.70
7762.52
18
1014.81
18.85
96.00
1110.81
8309.40
19
1081.65
19.90
101.33
1182.98
8849.28
20
1147.22
20.94
106.67
1253.88
9379.67
21
1211.16
21.99
112.00
1323.16
9897.91
22
1273.10
23.04
117.33
1390.44
10401.17
23
1332.62
24.09
122.67
1455.29
10886.30
24
1389.25
25.13
128.00
1517.25
11349.77
25
1442.42
26.18
133.33
1575.76
11787.45
26
1491.49
27.23
138.67
1630.15
12194.36
27
1535.58
28.27
144.00
1679.58
12564.09
28
1573.51
29.32
149.33
1722.84
12887.70
29
1603.32
30.37
154.67
1757.98
13150.59
30
1619.88
31.42
160.00
1779.88
13314.42
11 /7/2019

\ 15" OK
\ \ \ \ \ 625 \
\\ \ \ \ \\ 50\\
\ �\ 252 '
\\ \ \ / \\ S K-3 62s
NS Post2.50 ac. \
/ Inv. 630.90 ` \ \ \ ^ �// \ ` 8S�'o '111\�400 s.f.)
\ N// // �3 , \ \
\A)\\\,
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ir
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2'1.7'
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15" OK
\ N89°57'52"E 1706.27' e
/ 1631.26' I 7\ 15" OK >> /
13 OK
\ PROP. NAG SC 150 MATTING
/ SEE DETAIL 4, SH. 12
\ 140' REAR YARD SETBACK I /
623 — — --- — — — — °-
- ° 0„ OK
--- 625
00
00
\
� . XX \. X\ X
6.2� . 45��24
,
K +
\\ \\ ' PROPOSED UNION POWER
T.
�
x : ELECTRIC SUBSTATION
j . \\ \ \\—\ \\\\ �.\ - PAD ELEVATION = 625.0
+ H.P. RIDGE LINE DESIGNATION
\ \ - 625�0 DRAINAGE PURPOSES (TYP.)
\ \ '53,150
\\ ; s.f:
?s \ '
.625.10 6251.0
..0
SLOPE TRACKING, SEE
625.1 _ - - - DETAIL 1, SHT. 11
\ - - -STORM 625
\ \ \,290 PIPE 03
.624.50 - 00 CB-01 5,290
4�4 \ S..f .624 4� —
624.40. - �.CB
A- / l - 62r- \' - O PROPOSED FIBER ROLLS
PLACED @ 60' ON CENTER
P625-05
os5ac. 350 625.1. X (TYPICAL)
624.50624.50
(64-, QO s.f.) o STORM 0\ 9MH-01
PIPE 01 A
� ° \ —624-.50624.50. S. ���
615U
CB-04
WELL' f l\ I STORM co ,6 51 _
2"6�5.00 624
4.90 \\ �PIPE 05 I /
I
�.- STORM `89 v
� � � frn 7
24.50 PIPE 02 / 9
\ I I \ \ fi
C STORM 616
\..X� \ X : X `, X� X X X PIPE 06 \ —
Gr \ 1 II I \ \O /l /l \ \\ l - - \ \ -49,6 PIPE0RM 0411>0
Or SJ
OUTLET PROTECTION DISSIPATOR \
SEE DET. 11, SHT. 10FLA\ \
SEERDDEND ET. 1SECTION 0, SHT. 10
\
��, I \\ �)
SUBSTATION GRADING ENLAREGEMENT \ �� I I I , PROPOSED FIBER ROLLS ° 630 /
\ ) I / PLACED @ 60' ON CENTER \ \ \ \
GRAPHIC SCALE \ \ \�� I I / I (TYPICAL) \ 630
SEE DETAIL 12, SHT. 10 -O`` \\ \\ 625
20 D 10 2 RAI AGF PURPOSES (TYP.)
(IN FEET) r \\�� /// °� ��� \\ \\ \ \ ) �� \ \\ PROP. NAG SC 150 MATTING / //
1 INCH = 0 FT. I \ \ \ / \ \ \ \ I \ \ SEE DETAIL 4, SH. 12
PROPOSED TOP OF
LANDSCAPED BERM,
°� `S�j \\\\ /�\\ \\ \\ \ \ \ \ ELEVATION = 631.0--------/ 6„ O // //
,K
624.90
\ ,
625.00
PERMIT REVIEW 1
m
PROPOSED ROCK CHECK
OUTLET (TYPICAL)
SEE DETAIL SHEET 10
/
/
/
/
LEGEND
PROPERTY LINE
LIMITS OF DISTURBANCE
EDGE OF PAVEMENT
_ PROPOSED TRANSMISSION LINE —
\ \ GENERAL NOTES:
\ \ \ \ \ \ \ — — / / / / / / / PROP. TRANSMISSION LINE R/W — — —
\\\\ 1. FOR RIP RAP APRON SIZING, SEE 16872SDR DIET. 3 SHT. 3.
PROPOSED SUBSTATION FENCE X
2. FRAME AND GRATE - NCDOT STANDARD 840.29 —
3. TRAFFIC RATED PRECAST STRUCTURE NCDOT STANDARD 840.46 EXISTING MAJOR CONTOUREXISTING MINOR CONTOUR
--------------
624.40 ,� \ \ \ — _ _ , / 4. STORM DRAINAGE STRUCTURE DIMENSIONS ARE INNER LENGTH PROPOSED MAJOR CONTOUR
1 I \ \ \ \ \ \ \ —� — _ — _ — _ — — / / / — I AND WIDTH. PROPOSED MINOR CONTOUR
5. ALL PIPES TO BE CLASS III RCP UNLESS OTHERWISE SPECIFIED.
�' \ �\\ PROPOSED ACCESS ROAD EDGE
X \ ° \ \ \ 6. UNDERGROUND OIL CONTAINMENT SYSTEM (DRAINAGE PIPES 1,
2, 3, 5, AND 6) IS DESIGNED FOR THE 25 YEAR RAINFALL STORM EXISTING ROAD RIGHT-OF-WAY —
EVENT WHILE RETAINING 4,760 GALLONS OF OIL. EXISTING POWER POLE
�—
opd \ \ — _ — _ — — — — J / ' — — 7. UNDERGROUND OIL CONTAINMENT SYSTEM REQUIRES 0% PIPE PROPOSED STORM PIPE
�r \ \ \ SLOPE TO MAXIMIZE THE SYSTEM STORAGE CAPABILITIES IN THE
\ \ — — / — - EVENT OF A TRANSFORMER FAILURE. SEE 16872SDR DET. 5 SHT. PROPOSED STORM INLET -BOX
625 � � --_------- _- --
- _ �� — — — — — ' 3 FOR ADDITIONAL DETAILS. O \ / X \ G \ — _ — — — — — — \
El
624.50
G �
yg \ \ \ /O.
\ 624.5.0 1
TYP.) � � �
:. -- D
GRAPHIC SCALE
X \I I
ao o zo ao so \ 160
624.89 m m
( IN FEET)
1 INCH = 40 FT. \ \ \ \ Inv. \604.19
—OE
i
Stp,�\\ \\ \ /l \\ \\ \\ \\\----
625.10 ,
SST\ EXIST. MATURE TREE TO REMAIN
\o \\ \ 6, \ \ TREE SHALL BE PROTECTED FROM-
\ \ / C' , \ \ \ GRADING ACTIVITIES-
\ SEE DETAIL 9, SHT. 10
3 4. 4------ / //
PROPOSED STORM INLET - ROUND --
FLARED END W/ RIP -RAP OUTLET
PROPOSED SILT FENCE
EXCAVATED CONCRETE WASHOUT o e
o w
/ ROCK INLET PROTECTION
PROPOSED GRAVEL
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Jul 15, 2019 — 4:19pm C:\Users\dsherrill\OneDrlw — Pike Enterprises, LLC\FPS\Trinity — Union County\06_DWG\Trinity_07117.dwg

C
1 (7S3>
Watershed CB1 Watershed CB3
CB-1 CB-3
C -1
C B-2
CB-2
CWS2
C -3
C B-4
CB-4
WS4
Watershed CB2 Watershed CB4
S4
Reach on L
ink
CH-1
Channel
[3RJ
(new Reach)
C0]IIW:I
2R
(new Reach)
CH-2
Channel 2

Trinity Substation
07117_Trinity Printed 11/11/2019
Prepared by PIKE
HydroCAD® 10.00-25 s/n10975 ©2019 HydroCAD Software SolutionsLLC Page2
Area Listing (all
nodes)
Area CN Description
(acres) (subcatchment-numbers)
1.219 80 >75% Grass cover, Good, HSG D (CH-1, CH-2)
2.119 91 Gravel roads, HSG D (CH-1, CH-2, WS1, WS2,
3.338 87 TOTAL AREA
Soil Listing (all
nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000 HSG A
0.000 HSG B
0.000 HSG C
3.338 HSG D CH-1, CH-2, WS1, WS2, WS3,
0.000 Other
3.338 TOTAL AREA
Ground Covers (all
nodes)
HSG- HSG- HSG- HSG- Othe
A B C D r
Total Ground
(acres Cover
Subcatchm
ent
0.000 0.000 0.000 1.219 0.000 1.219 >75% Grass cover, CH-1,
CH-2
0.000 0.000 0.000 2.119 0.000 2.119 Gravel roads CH-1,
CH-2,
WS1,
WS2,
WS3,
0.000 0.000 0.000 3.338 0.000 3.338 TOTAL AREA

Trinity Substation
07117_Trinity
Prepared by PIKE Engineering Printed 11/11/2019
HydroCAD® 10.00-25 s/n 10975 © 2019 HydroCAD Software Solutions LLC Page 6
Pipe Listing (all nodes)
Line# Node In -Invert Out -Invert Length Slope n DiamMidth Height Inside -Fill
Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches)
1
CB-1
619.50
619.50
74.0
0.0000
0.012
30.0
0.0
0.0
2
CB-2
619.50
619.50
129.0
0.0000
0.012
30.0
0.0
0.0
3
CB-3
619.50
619.50
74.0
0.0000
0.012
30.0
0.0
0.0
4
CB-4
619.50
619.50
48.0
0.0000
0.012
30.0
0.0
0.0
5
OC-MH
618.80
618.50
44.0
0.0068
0.012
12.0
0.0
0.0

07117_Tri nity
Prepared by PIKE Engineering Printed 11/9/2019
HydroCAD® 10.00-25 s/n 10975 © 2019 HydroCAD Software Solutions LLC Page 1
Pipe Listing (selected nodes)
Line# Node In -Invert Out -Invert Length Slope n DiamMidth Height Inside -Fill
Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches)
1 OC-MH 618.80 618.50 44.0 0.0068 0.012 12.0 0.0 0.0

Trinity Substation
07117_Trinity Type 1124-hr 10yrRainfall=5.05"
Prepared by PIKE Engineering Printed 11/11/2019
HydroCAD® 10.00-25 s/n 10975 © 2019 HydroCAD Software Solutions LLC Page 7
Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points x 2
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment CH-1: Channel 1
Runoff Area=52,275 sf 0.00% Impervious Runoff Depth=3.61"
Flow Length=480'
Slope=0.0100 '/' Tc=11.6 min CN=87 Runoff=6.12 cfs 0.361 of
Subcatchment CH-2: Channel 2
Runoff Area=71,925 sf 0.00% Impervious Runoff Depth=3.51"
Flow Length=490'
Slope=0.0100 '/' Tc=11.9 min CN=86 Runoff=8.15 cfs 0.483 of
Subcatchment WS1: Watershed CB1
Runoff Area=5,300 sf 0.00% Impervious Runoff Depth=4.03"
Flow Length=85'
Slope=0.0130 '/' Tc=1.2 min CN=91 Runoff=0.94 cfs 0.041 of
Subcatchment WS2: Watershed CB2
Runoff Area=5,300 sf 0.00% Impervious Runoff Depth=4.03"
Flow Length=45'
Slope=0.0100 '/' Tc=0.8 min CN=91 Runoff=0.95 cfs 0.041 of
Subcatchment WS3: Watershed CB3
Runoff Area=5,300 sf 0.00% Impervious Runoff Depth=4.03"
Flow Length=85'
Slope=0.0130 '/' Tc=1.2 min CN=91 Runoff=0.94 cfs 0.041 of
Subcatchment WS4: Watershed CB4
Runoff Area=5,300 sf 0.00% Impervious Runoff Depth=4.03"
Flow Length=45'
Slope=0.0100 '/' Tc=0.8 min CN=91 Runoff=0.95 cfs 0.041 of
Reach 2R: (new Reach) Avg. Flow Depth=1.47' Max Vet=0.53 fps Inflow=8.15 cfs 0.483 of
n=0.240 L=480.0' S=0.0100 '/' Capacity=18.91 cfs Outflow=5.21 cfs 0.483 of
Reach 3R: (new Reach) Avg. Flow Depth=1.29' Max Vet=0.48 fps Inflow=6.12 cfs 0.361 of
n=0.240 L=475.0' S=0.0095 '/' Capacity=18.40 cfs Outflow=3.75 cfs 0.361 of
Pond CB-1: CB-1 Peak EIev=622.04' Storage=49 cf Inflow=0.94 cfs 0.041 of
30.0" Round Culvert n=0.012 L=74.0' S=0.0000 '/' Outflow=1.13 cfs 0.042 of
Pond CB-2: CB-2 Peak EIev=622.04' Storage=49 cf Inflow=1.85 cfs 0.083 of
30.0" Round Culvert n=0.012 L=129.0' S=0.0000 '/' Outflow=1.82 cfs 0.084 of
Pond CB-3: CB-3 Peak EIev=622.04' Storage=49 cf Inflow=0.94 cfs 0.041 of
30.0" Round Culvert n=0.012 L=74.0' S=0.0000 '/' Outflow=1.13 cfs 0.042 of
Pond CB-4: CB-4 Peak EIev=624.74' Storage=269 cf Inflow=3.68 cfs 0.166 of
30.0" Round Culvert n=0.012 L=48.0' S=0.0000 '/' Outflow=6.92 cfs 0.175 of
Pond OC-MH: Oil MH Peak EIev=623.27' Storage=68 cf Inflow=6.92 cfs 0.175 of
12.0" Round Culvert n=0.012 L=44.0' S=0.0068 '/' Outflow=5.95 cfs 0.175 of
Total Runoff Area = 3.338 ac Runoff Volume = 1.008 of Average Runoff Depth = 3.63"
100.00% Pervious = 3.338 ac 0.00% Impervious = 0.000 ac

Trinity Substation
07117_Trinity Type 1124-hr 25yrRainfall=6.11"
Prepared by PIKE Engineering Printed 11/11/2019
HydroCAD® 10.00-25 s/n 10975 © 2019 HydroCAD Software Solutions LLC Page 68
Summary for Pond OC-MH: Oil MH
[44] Hint: Outlet device #1 is below defined storage
[80] Warning: Exceeded Pond C13-4 by 0.10' @ 0.02 hrs (0.85 cfs 0.009 af)
Inflow Area = 0.487 ac, 0.00% Impervious, Inflow Depth = 5.36" for 25yr event
Inflow = 6.92 cfs @ 0.00 hrs, Volume= 0.217 of
Outflow = 5.95 cfs @ 0.01 hrs, Volume= 0.217 af, Atten= 14%, Lag= 0.6 min
Primary = 5.95 cfs @ 0.01 hrs, Volume= 0.217 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 623.27' @ 0.01 hrs Surf.Area= 16 sf Storage= 68 cf
Plug -Flow detention time= 5.7 min calculated for 0.216 of (100% of inflow)
Center -of -Mass det. time= (not calculated: outflow precedes inflow)
Volume Invert Avail.Storage Storage Description
#1 624.00' 449 cf Custom Stage Data (Irregular) Listed below (Recalc)
#2 619.00' 80 cf 4.00'W x 4.00'L x 5.00'H MH Box
529 cf Total Available Storage
Elevation
Surf.Area Perim. Inc.Store Cum.Store
Wet.Area
(feet)
(sq-ft)
(feet) (cubic -feet) (cubic -feet)
(sq-ft)
624.00
48
32.0 0 0
48
624.50
300
25.0 78 78
83
625.00
1,300
66.0 371 449
381
Device Routing
Invert
Outlet Devices
#1 Primary
618.80'
12.0" Round Culvert RCP
L= 44.0' CMP, projecting, no headwall,
Ke= 0.900
Inlet / Outlet Invert= 618.80' / 618.50' S=
0.0068 '/' Cc= 0.900
n= 0.012, Flow Area= 0.79 sf
Primary OutFlow Max=5.95 cfs @ 0.01 hrs HW=623.27' (Free Discharge)
L1=Culvert RCP (Inlet Controls 5.95 cfs @ 7.57 fps)

07117_Trinity Type 1124-hr 25yrRainfall=6.11"
Prepared by PIKE Engineering Printed 11/11/2019
HydroCAD® 10.00-25 s/n 10975 © 2019 HydroCAD Software Solutions LLC Page 108
w
1
jj
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)
Pond OC-MH: Oil MH
Stage -Discharge
3 4
Discharge (cfs)
❑ Inflow
❑ Primary
■ Primary

Hydraflow Storm Sewers Extension for Autodesk® AutoCAD® Civil 3D® Plan
4 5
3 2 Outfall
Project File: Storm-2.stm Number of lines: 5 Date: 11/7/2019
Storm Sewers 02.00

Storm Sewer Tabulation
Page 1
Station
Len
Drng Area
Rnoff
Area x C
Tc
Rain
Total
Cap
Vol
Pipe
Invert Elev
HGL Elev
Grnd / Rim Elev
Line ID
coeff
(1)
flow
full
Line
To
Incr
Total
Incr
Total
Inlet
Syst
Size
Slope
Dn
Up
Dn
Up
Dn
Up
Line
(ft)
(ac)
(ac)
(C)
(min)
(min)
(in/hr)
(cfs)
(cfs)
(ft/s)
(in)
M
(ft)
(ft)
(ft)
(ft)
(ft)
(ft)
5
2
74.000
0.02
0.02
0.02
0.00
0.00
5.0
5.0
7.0
0.02
0.00
0.00
30
0.00
619.50
619.50
622.00
622.00
624.50
624.40
STRM PIPE-03
4
3
74.000
0.02
0.02
0.02
0.00
0.00
5.0
5.0
7.0
0.02
0.00
0.00
30
0.00
619.50
619.50
622.00
622.00
624.50
624.40
STRM PIPE-01
3
2
129.000
0.02
0.04
0.02
0.00
0.00
5.0
270.4
0.8
0.04
0.00
0.13
30
0.00
619.50
619.50
619.78
619.78
624.50
624.50
STRM PIPE-02
2
1
48.000
0.02
0.08
0.02
0.00
0.00
5.0
502.2
0.5
0.08
0.00
0.84
30
0.00
619.50
619.50
619.59
619.78
624.55
624.50
STRM PIPE-04
1
End
43.818
0.02
0.10
0.02
0.00
0.00
5.0
545.5
0.4
0.10
2.41
1.51
12
0.46
619.10
619.30
619.23
619.45
620.79
624.55
STRM PIPE-06
Project File. Storm-2.stm
Number of lines: 5
Run Date: 111712019
NOTES:Intensity = 84.35 / (Inlet time + 15.10) ^ 0.83; Return period =Yrs. 10 ; c = cir e = ellip b = box
Storm Sewers 02.00

Storm Sewer Inlet Time Tabulation
Page 1
Line
Line ID
Tc
Sheet Flow
Shallow Concentrated Flow
Channel Flow
Total
No.
Method
n-
flow
2-yr
Land
Travel
flow
Water
Surf
Ave
Travel
X-sec
Wetted
Chan
n-
Vel
flow
Travel
Travel
Value
Length
24h P
Slope
Time
Length
Slope
Descr
Vel
Time
Area
Perim
Slope
Value
Length
Time
Time
(ft)
(in)
(%)
(min)
(ft)
M
(ft/s)
(min)
(sqft)
(ft)
M
(ft)
(min)
(min)
5
STRM PIPE-03
User
5.00
4
STRM PIPE-01
User
5.00
3
STRM PIPE-02
User
5.00
2
STRM PIPE-04
User
5.00
1
STRM PIPE-06
User
5.00
Project File: Storm-2.stm
Min. Tc used for intensity calculations = 5 min
Number of lines: 5
Date: 11/7/2019
Storm Sewers 02

Hydraulic Grade Line Computations
Page 1
Line
Size
Q
Downstream
Len
Upstream
Check
JL
Minor
coeff
loss
Invert
HGL
Depth
Area
Vel
Vel
EGL
Sf
Invert
HGL
Depth
Area
Vel
Vel
EGL
Sf
Ave
Enrgy
elev
elev
head
elev
elev
elev
head
elev
Sf
loss
(in)
(cfs)
(ft)
(ft)
(ft)
(sqft)
(ft/s)
(ft)
(ft)
M
(ft)
(ft)
(ft)
(ft)
(sqft)
(ft/s)
(ft)
(ft)
M
M)
(ft)
(K)
(ft)
5
30
0.02
619.50
622.00
2.50*
4.91
0.00
0.00
622.00
0.000
74.000
619.50
622.00
2.50**
4.91
0.00
0.00
622.00
0.000
0.000
n/a
1.00
0.00
4
30
0.02
619.50
622.00
2.50*
4.91
0.00
0.00
622.00
0.000
74.000
619.50
622.00
2.50**
4.91
0.00
0.00
622.00
0.000
0.000
n/a
1.00
0.00
3
30
0.04
619.50
619.78
0.28
0.30
0.14
0.00
619.78
0.001
129.00
619.50
619.78
0.28
0.30
0.13
0.00
619.78
0.001
0.001
0.002
1.50
0.00
2
30
0.08
619.50
619.59
0.09*
0.06
1.41
0.03
619.62
0.648
48.000
619.50
619.78
0.28
0.30
0.27
0.00
619.78
0.006
0.327
0.157
1.50
0.00
1
12
0.10
619.10
619.23
0.13
0.06
1.68
0.04
619.27
0.615
43.818
619.30
619.45
0.15
0.08
1.34
0.03
619.48
0.322
0.468
0.205
0.50
0.01
Project File. Storm-2.stm
Number of lines: 5
TRun Date: 11/7/2019
Notes: * depth assumed; ** Critical depth. ; c = cir e = ellip b = box
Storm Sewers 02.00