SW1200601_2020-08-31 Sanstone Storm & EC Calcs_20200831

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BRODKS Planning & Project Management 1 Civil Engineering Surveying
Soil Science Services % Environmental Engineering & Services
EN G IN EER IN U A s SO 1 ATE s 17 Arlington Street 1 Asheville NC28801 I www.brooksea.com / 828-232-4700
Sanstone Office & Storage Expansion
Mills River, Henderson County, North Carolina
Stormwater and EC Calculations
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Original: May 29, 2020
Revised: August 31, 2020
Brandon M. Thomas, PE

TABLE OF CONTENTS
Storm Water & Erosion Control Narrative...................................................... 1-3
NOAA Precipitation Charts, USGS, FEMA, Soils, SHWT, and Wetlands..............Appendix 1
Collection System Calculations..................................................................Appendix 2
Hydrologic Model and BMP Design.............................................................Appendix 3
Erosion Control Calculations and Specifications .............................................Appendix 4

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Project Description
The proposed Sanstone Office & Storage Expansion is located on two adjacent parcels
(Henderson County PINs: 9632-48-7869 and 9632-48-9561) on Old Haywood Road in
Mills River, North Carolina. The development for the 6.00-acre site consists of one
office building and one storage building. The plans also incorporate a second storage
building to be constructed at a later date. Two driveway connections will be made to the
parking areas associated with the existing Sanstone office building and healthcare
facility.
This report addresses requirements to meet current NPDES Construction and Post
Construction Activities. The site is located outside of a Water Supply Watershed
Overlay District and is therefore designed based on NCDEQ design criteria.
Existing Site Conditions
The existing site is vacant and former farmland. The western half of the property is
wooded and the eastern portion along the Old Haywood Road frontage is a grass field.
The soils for the site are classified by the NRCS as Hayesville loam (HyB & HyC) and
Delanco (dillard) loam (DeB). HyB soils are classified as Hydrologic Soil Group (HSG)
Type B, whereas HyC and DeB are considered to by HSG Type C. The site primarily
drains from west to southeast to an existing drainage ditch along Old Haywood Road.
For analysis purposes, this drainage basin was split in to two areas because runoff exits
the site at two separate locations and rejoins at a common point offsite. The northern
portion of the site drains to the storm drainage system for the existing Sanstone office
building and healthcare facility.
Proposed Developed Conditions
The proposed development is considered high -density and is designed to achieve a
runoff treatment for the first inch with a piped stormwater conveyance system and a
bioretention cell. Runoff from impervious areas associated with buildings, paved drives
with curb & gutter, sidewalk, and parking are to be captured to the extent practical.
Approximately 431 SF of impervious driveway is proposed to drain to storm drainage
infrastructure associated with the existing Sanstone office and healthcare facility (The
Henderson-Beystone Parcel aka The Lodge at Mills River — SanStone Health & Rehab).
The bioretention cell is designed to accommodate approximately 9,100 SF of
impervious area for a future storage building and associated pavement adjacent to the
proposed storage building. Offsite drainage from adjacent western parcels drains to
swales located that allows this stormwater to bypass the proposed SCM.
During construction a temporary construction entrance will be located along Old
Haywood Road in order to minimize construction traffic for the existing healthcare
facility.

Purpose of Report
The purpose of this analysis is to show that the site will be in compliance with NCDEQ
stormwater regulations.
Procedure
Collection System:
The proposed collection system was sized to adequately convey the 25-year, 24-hour
storm. Drainage areas were delineated for each proposed inlet in addition to Rational
`C' coefficients and time of concentration based on the TR-55 method. Energy
dissipation will be handled with riprap pads sized for the 25-year storm. Refer to the
provided plan set for a drainage summary.
Water Quantity:
The SCS Method using a 24-hour, Type II storm was used to determine the pre -
developed and developed annual peak stormwater discharges generated from this site.
The HydroCAD runoff routing program was used to determine these peak flows and
storm volumes as well as routing through the detention basin and bypass areas.
Stage/discharge rates for the ponds were determined based on storage, culvert and
broad crested weir equations within Hydrocad.
Calculations for the 25-year storm event were performed to show the pond is
adequately sized to pass the 25-year storm event. A vegetated spillway with matting
has been provided along with riser/barrel outlet control structures for primary drainage
from basin areas.
Water Quality:
The Simple Method was used to determine the runoff volume for the first -inch of rainfall.
The bioretention cell was then designed to allow a maximum of one -foot of ponding
above the media mix for this design volume. The underdrain system is designed to
discharge the first inch between 2-5 days after the rainfall event.
Seasonal High Water Table (SHWT):
Per NCDEQ MDC guidelines for bioretention cells, the lowest point shall be a minimum
of two feet above the SHWT. On April 21, 2020, Land Resources Management
excavated a test pit at the location of the SCM. The pit was excavated to a depth of 75"
(6.25') with no sign of the SHWT. Existing elevation at the pit location is approximately
2182.0' and the proposed bottom of the bioretention underdrain system is 2178.75'.
Therefore, the bottom of the bioretention cell is at least 2' above the SHWT.
Calculations
Drainage maps are included in the plans associated with this project. These maps
show the predeveloped and developed conditions. A summary of the entire drainage
area for the site and each individual drainage area within the site is included in this

report. Erosion Control calculations including skimmer basin design are included in
Appendix 4.
Stormwater Results
The following table shows the pre/post runoff rates for the project. There is no increase
the annual discharge for Basins 1 & 2 that drain to Old Haywood Road. There is a 0.01
CFS increase in runoff from Basin 3 draining to the storm drainage system for the
existing office and healthcare facility due to a reduction in time of concentration and
wooded area. The 25-year storm calculations show the proposed detention ponds are
adequate to pass the 25-year storm event.
Basin Name
1-Year
25-Year
25-Year Ponding
(cfs)
(cfs)
(Elevation - feet)
Existing Basin 1
2.16
10.09
To BMP #1
4.48
16.68
Out BMP #1
0.33
13.84
2182.90
BMP Bypass
1.19
4.32
Proposed Basin 1
1.19
15.60
Existing Basin 2
0.33
4.35
Proposed Basin 2
0.20
1.90
Existing Basin 3
0.08
1.94
Proposed Basin 3
0.09
0.77
Recommendations
Brooks Engineering recommends that the proposed development utilize stormwater
management facilities as outlined in this study in order to mitigate developed peak
stormwater discharges per NCDEQ regulations. Routine maintenance will need to be
performed in order for the stormwater management areas to operate as designed.

Appendix "l"

C!!t[I'AKIKIl
Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: Mills River, North Carolina, USA*�'°
Latitude: 35.4251*, Longitude:-82.5765°
Elevation: 2225.91 ft *��������
L *source: ESRI Maps
source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1
Average recurrence interval (years)
Duration
1 2 5 10 25 50 100 200 500 1000
5-min]F 0.367 0.437 0.523 0.589 0.675 0.740 0.806 0.872 0.957 1.03
(0.331-0.408) (0.394-0.484) (0.472-0.581) (0.530-0.652) (0.602-0.746) (0.657-0.818) (0.712-0.893) (0.764-0.968) (0.829-1.07) (0.880-1.15)
[10-min]F 0.586 0.698 0.838 0.942 1.08 1.18 1.28 1.38 1.51 1.62
(0.528-0.651) (0.631-0.775) (0.755-0.930) (0.847-1.04) (0.960-1.19) (1.05-1.30) (1.13-1.42) (1.21-1.54) (1.31-1.69) (1.39-1.82)
[15-min]F 0.732 0.878 1.06 1.19 1.36 1.49 1.62 1.74 1.91 2.03
(0.660-0.814) (0.793-0.974) (0.955-1.18) (1.07-1.32) (1.22-1.51) (1.32-1.65) (1.43-1.79) (1.53-1.94) (1.65-2.13) (1.74-2.28)
30-min 1.00 1.21 1.51 1.73 2.02 2.25 2.48 2.71 3.03 3.29
(0.905-1.12) (1.10-1.35) (1.36-1.67) (1.55-1.91) (1.80-2.23) (1.99-2.48) (2.19-2.75) (2.38-3.02) (2.63-3.39) (2.82-3.69)
60-min 1.25 1.52 1.93 2.25 2.69 3.05 3.42 3.81 4.35 4.80
(1.13-1.39) (1.37-1.69) (1.74-2.14) (2.02-2.49) (2.40-2.97) (2.70-3.37) (3.02-3.78) (3.34-4.23) (3.77-4.86) (4.11-5.39)
[72-hr 1.47 1.78 2.25 2.62 3.14 3.56 4.01 4.48 5.15 5.68
(1.32-1.63) (1.61-1.97) (2.02-2.48) (2.34-2.90) (2.79-3.48) (3.15-3.95) (3.52-4.45) (3.90-4.98) (4.42-5.74) (4.83-6.38)
3-hr 1.57 1.90 2.38 2.77 3.35 3.83 4.33 4.89 5.68 6.33
(1.42-1.76) (1.71-2.11) (2.14-2.64) (2.48-3.08) (2.97-3.72) (3.37-4.25) (3.79-4.82) (4.22-5.44) (4.83-6.37) (5.33-7.14)
[76-hr 1.97 2.35 2.89 3.36 4.04 4.62 5.24 5.92 6.90 7.73
(1.80-2.17) (2.14-2.58) (2.64-3.18) (3.05-3.69) (3.64-4.44) (4.12-5.07) (4.63-5.77) (5.17-6.52) (5.93-7.65) (6.56-8.62)
12-hr 2.48 2.96 3.63 4.17 4.92 5.53 6.16 6.82 7.72 8.44
(2.29-2.71) (2.72-3.23) (3.34-3.96) (3.82-4.55) (4.49-5.37) (5.03-6.04) (5.56-6.74) (6.11-7.48) (6.85-8.55) (7.42-9.41)
24-hr 2.97 3.56 4.37 5.02 5.92 6.65 7.40 8.18 9.28 10.2
(2.75-3.21) (3.30-3.85) (4.05-4.73) (4.64-5.43) (5.45-6.39) (6.10-7.18) (6.76-7.98) (7.43-8.84) (8.35-10.0) (9.06-11.0)
2-day 3.53 4.21 5.13 5.86 6.87 7.68 8.52 9.38 10.6 11.6
(3.29-3.80) (3.92-4.53) (4.78-5.51) (5.45-6.29) (6.36-7.37) (7.09-8.24) (7.83-9.15) (8.58-10.1) (9.60-11.4) (10.4-12.5)
3-day 3.77 4.49 5.43 6.17 7.17 7.97 8.79 9.63 10.8 11.7
(3.52-4.04) (4.19-4.81) (5.06-5.81) (5.74-6.60) (6.66-7.67) (7.38-8.54) (8.11-9.43) (8.84-10.3) (9.82-11.6) (10.6-12.6)
4-day 4.01 4.77 5.72 6.47 7.48 8.27 9.07 9.88 11.0 11.9
(3.75-4.28) (4.47-5.10) (5.35-6.11) (6.04-6.91) (6.96-7.98) (7.67-8.83) (8.38-9.70) (9.10-10.6) (10.0-11.8) (10.8-12.8)
7-day 4.69 5.57 6.68 7.56 8.75 9.70 10.7 11.7 13.0 44.1
(4.40-5.02) (5.23-5.96) (6.26-7.14) (7.07-8.08) (8.16-9.35) (9.03-10.4) (9.89-11.4) (10.8-12.5) (11.9-14.0) (12.8-15.2)
10-day 5.38 6.37 7.55 8.49 9.76 10.8 11.8 12.8 14.2 15.3
(5.08-5.71) (6.01-6.76) (7.14-8.02) (8.01-9.01) (9.18-10.4) (10.1-11.4) (11.0-12.5) (11.9-13.6) (13.1-15.2) (14.1-16.4)
20-day 7.32 8.61 9.99 11.1 12.5 13.5 14.6 15.6 16.9 17.9
(6.94-7.73) (8.16-9.10) (9.47-10.6) (10.5-11.7) (11.8-13.2) (12.8-14.3) (13.7-15.4) (14.6-16.5) (15.8-17.9) (16.6-19.0)
30-day 8.98 10.5 12.1 13.2 14.6 15.7 16.7 17.7 18.9 99.7
(8.53-9.46) (10.0-11.1) (11.5-12.7) (12.5-13.9) (13.9-15.4) (14.9-16.5) (15.8-17.6) (16.7-18.6) (17.7-19.9) (18.5-20.9)
45-day 11.4 13.4 15.0 16.3 17.8 18.8 19.8 20.7 21.7 22.6
(10.9-12.0) (12.7-14.0) (14.3-15.8) (15.5-17.1) (16.9-18.7) (17.9-19.8) (18.8-20.8) (19.6-21.7) (20.6-22.9) (21.2-23.7)
60-day 13.7 16.0 17.9 19.2 20.8 21.9 22.9 23.8 24.9 25.6
(13.1-14.4) (15.3-16.8) (17.0-18.8) (18.3-20.2) (19.8-21.9) (20.9-23.1) (21.8-24.1) (22.6-25.1) (23.6-26.3) (24.2-27.1)
Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for
a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are
not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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PF graphical
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4/14/2020 Precipitation Frequency Data Server
PIDS-based clep,tgii-duiratiion-firequieiicy (DIDF) cuirves
Latitude: 35,.4251"., Longitude:: -82.5765'
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Maps & aerials
Small scale terrain
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(years)
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Precipitation Frequency Data Server
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National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring, MD 20910
Questions?: [e-mail]
Disclaimer
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C!!t[I'AKIKIl
Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: Mills River, North Carolina, USA*�'°
Latitude: 35.4251*, Longitude:-82.5765°
Elevation: 2225.91 ft *��������
L *source: ESRI Maps
source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1
Average recurrence interval (years)
Duration
1
2
5
10
25
50
100
200
500
1000
5-min
4.40
(3.97-4.90)
5.24
(4.73-5.81)
6.28
(5.66-6.97)
7.07
(6.36-7.82)
8.10
(7.22-8.95)
8.88
(7.88-9.82)
9.67
(8.54-10.7)
10.5
(9.17-11.6)
11.5
(9.95-12.8)
12.3
(10.6-13.8)
3.52
4.19
5.03
5.65
6.46
7.07
7.69
8.29
9.08
9.70
10-min
(3.17-3.91)
(3.79-4.65)
(4.53-5.58)
(5.08-6.26)
(5.76-7.14)
(6.28-7.82)
(6.79-8.51)
(7.27-9.21)
(7.87-10.2)
(8.31-10.9)
2.93
3.51
4.24
4.77
5.45
5.97
6.48
6.98
7.62
8.11
15-min
(2.64-3.26)
(3.17-3.90)
(3.82-4.71)
(4.28-5.28)
(4.86-6.03)
(5.30-6.60)
(5.72-7.1 7)
(6.12-7.74)
(6.60-8.52)
(6.96-9.12)
2.01
2.42
3.01
3.45
4.04
4.50
4.96
5.43
6.07
6.57
30-min
(1.81-2.23)
(2.19-2.69)
(2.71-3.34)
(3.10-3.82)
(3.60-4.47)
(3.99-4.97)
(4.38-5.49)
(4.76-6.03)
(5.26-6.78)
(5.63-7.38)
1.25
1.52
1.93
2.25
2.69
3.05
3.42
3.81
4.35
4.80
60-min
(1.13-1.39)
(1.37-1.69)
(1.74-2.14)
(2.02-2.49)
(2.40-2.97)
(2.70-3.37)
(3.02-3.78)
(3.34-4.23)
(3.77-4.86)
(4.11-5.39)
0.733
0.890
1.12
1.31
1.57
1.78
2.00
2.24
2.57
2.84
[72F7]F
(0.660-0.813)
(0.802-0.984)
(1.01-1.24)
(1.17-1.45)
(1.40-1.74)
(1.57-1.97)
(1.76-2.22)
(1.95-2.49)
(2.21-2.87)
(2.41-3.19)
0.524
0.631
0.792
0.923
1.12
1.27
1.44
1.63
1.89
2.11
3-hr
(0.473-0.585)
(0.569-0.702)
(0.712-0.879)
(0.827-1.02)
(0.990-1.24)
(1.12-1.42)
(1.26-1.60)
(1.41-1.81)
(1.61-2.12)
(1.77-2.38)
0.329
0.392
0.483
0.562
0.675
0.771
0.875
0.988
1.15
1.29
[6F7]F
(0.301-0.362)
(0.358-0.431)
(0.440-0.531)
(0.510-0.617)
(0.607-0.741)
(0.688-0.846)
(0.773-0.963)
(0.863-1.09)
(0.990-1.28)
(1.10-1.44)
0.206
0.246
0.301
0.346
0.408
0.459
0.511
0.566
0.641
0.701
[�12-hr]F
(0.190-0.225)
(0.226-0.268)
(0.277-0.329)
(0.317-0.378)
(0.373-0.446)
(0.417-0.501)
(0.462-0.559)
(0.507-0.621)
(0.569-0.709)
(0.615-0.781)
0.124
0.148
0.182
0.209
0.247
0.277
0.308
0.341
0.387
0.423
[�24-hr]F
(0.115-0.134)
(0.137-0.161)
(0.169-0.197)
(0.193-0.226)
(0.227-0.266)
(0.254-0.299)
(0.282-0.333)
(0.310-0.368)
(0.348-0.418)
(0.378-0.459)
0.074
0.088
0.107
0.122
0.143
0.160
0.177
0.195
0.220
0.240
2-day]F
(0.069-0.079)
(0.082-0.094)
(0.099-0.115)
(0.113-0.131)
(0.132-0.153)
(0.148-0.172)
(0.163-0.191)
(0.179-0.210)
(0.200-0.238)
(0.216-0.260)
0.052
0.062
0.075
0.086
0.100
0.111
0.122
0.134
0.150
0.163
3-day]F
(0.049-0.056)
(0.058-0.067)
(0.070-0.081)
(0.080-0.092)
(0.092-0.107)
(0.102-0.119)
(0.113-0.131)
(0.123-0.144)
(0.136-0.161)
(0.147-0.175)
0.042
0.050
0.060
0.067
0.078
0.086
0.094
0.103
0.114
0.124
4-day]F
(0.039-0.045)
(0.047-0.053)
(0.056-0.064)
(0.063-0.072)
(0.072-0.083)
(0.080-0.092)
(0.087-0.101)
(0.095-0.110)
(0.105-0.123)
(0.112-0.133)
0.028
0.033
0.040
0.045
0.052
0.058
0.064
0.069
0.078
0.084
7-day]F
(0.026-0.030)
(0.031-0.035)
(0.037-0.043)
(0.042-0.048)
(0.049-0.056)
(0.054-0.062)
(0.059-0.068)
(0.064-0.074)
(0.071-0.083)
(0.076-0.090)
0.022
0.027
0.031
0.035
0.041
0.045
0.049
0.053
0.059
0.064
[10-day]F
(0.021-0.024)
(0.025-0.028)
(0.030-0.033)
(0.033-0.038)
(0.038-0.043)
(0.042-0.048)
(0.046-0.052)
(0.050-0.057)
(0.055-0.063)
(0.059-0.068)
0.015
0.018
0.021
0.023
0.026
0.028
0.030
0.032
0.035
0.037
20-day
(0.014-0.016)
(0.017-0.019)
(0.020-0.022)
(0.022-0.024)
(0.025-0.027)
(0.027-0.030)
(0.029-0.032)
(0.030-0.034)
(0.033-0.037)
(0.035-0.040)
0.012
0.015
0.017
0.018
0.020
0.022
0.023
0.025
0.026
0.027
30-day
(0.012-0.013)
(0.014-0.015)
(0.016-0.018)
(0.017-0.019)
(0.019-0.021)
(0.021-0.023)
(0.022-0.024)
(0.023-0.026)
(0.025-0.028)
(0.026-0.029)
0.011
0.012
0.014
0.015
0.016
0.017
0.018
0.019
0.020
0.021
[Fday]F
(0.010-0.011)
(0.012-0.013)
(0.013-0.015)
(0.014-0.016)
(0.016-0.017)
(0.017-0.018)
(0.017-0.019)
(0.018-0.020)
(0.019-0.021)
(0.020-0.022)
0.010
0.011
0.012
0.013
0.014
0.015
0.016
0.017
0.017
0.018
60-day
(0.009-0.010)
(0.011-0.012)
(0.012-0.013)
(0.013-0.014)
(0.014-0.015)
(0.014-0.016)
(0.015-0.017)
(0.016-0.017)
(0.016-0.018)
(0.017-0.019)
Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a
given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.4251 & Ion =-82.5765&data=intensity&units=english&series=pds 1 /4

4/14/2020
111010101GON
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Precipitation Frequency Data Server
IRDS-based iiintenisity-duratiorii-frequency (DIF) curves
Latitude: 35,.4251"., Longitude: -82.5765'
0001 I
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NOAA Atlas 14, VOILIme 2, Version 3, Created fGMT�: Tue Api, 14 20:04:19 2020,
Back to Top
Maps & aerials
Small scale terrain
Average recurrence
imprVal
(years)
2
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https://hdsc.nws.noaa.gov/hdsc/pfds/pfds-printpage. html?lat=35.4251 & Ion =-82.5765&data= intensity&u nits=e ng lish&series=pds 2/4

C!f[I'AKIN11
Precipitation Frequency Data Server
Large scale map
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https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.4251 & Ion =-82.5765&data=intensity&units=english&series=pds 3/4

Precipitation Frequency Data Server
Back to Top
US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring, MD 20910
Questions?: [e-mail]
Disclaimer
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.htmI?Iat=35.4251 &Ion=-82.5765&data=intensity&units=english&series=pds 4/4

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/, eooGEsxHor uDR �
? n� FIRM 37009632001

Hydrologic Soil Group —Henderson County, North Carolina
(SANSTONE_BOUNDARY)
v
m
356800 356830 356860 356890 356920 356950 356980 357010 357040
35° 25' 32" N
357070 357100
357010 357040 357070 357100
v
m
357130
S2 35° 25' 32" N
4/3/2020
Pagel of 4

Hydrologic Soil Group —Henderson County, North Carolina
(SANSTONE_BOUNDARY)
MAP LEGEND
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating
Polygons
0
A
0
A/D
D
B
®
B/D
0
C
0
C/D
0
D
Q
Not rated or not available
Soil Rating
Lines
"""'01
A
r�0"
A/D
B
rw
B/D
C
r ux"
C/D
r�
D
01 10,
Not rated or not available
Soil Rating
Points
A
13
A/D
®
B
®
B/D
MAP INFORMATION
® C
The soil surveys that comprise your AOI were mapped at
1:20,000.
13 C/D
D
Warning: Soil Map may not be valid at this scale.
® Not rated or not available
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
Water Features
line placement. The maps do not show the small areas of
Streams and Canals
contrasting soils that could have been shown at a more detailed
scale.
Transportation
Rails
Please rely on the bar scale on each map sheet for map
Interstate Highways
measurements.
�v US Routes
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Major Roads
Coordinate System: Web Mercator (EPSG:3857)
Local Roads
Maps from the Web Soil Survey are based on the Web Mercator
Background
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Aerial Photography
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: Henderson County, North Carolina
Survey Area Data: Version 19, Sep 16, 2019
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: May 21, 2015—Nov
28, 2017
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.
uSd')A; Natural Resources Web Soil Survey 4/3/2020
Conservation Service National Cooperative Soil Survey Page 2 of 4

Hydrologic Soil Group —Henderson County, North Carolina
SANSTONE_BOUNDARY
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
DeB
Delanco (dillard) loam, 2
to 7 percent slopes
C
0.2
2.7%
HyB
Hayesville loam, 2 to 7
percent slopes
B
3.6
59.5%
HyC
Hayesville loam, 7 to 15
percent slopes
C
2.3
37.8%
Totals for Area of Interest
6.0
100.0%
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.
uSDA Natural Resources Web Soil Survey 4/3/2020
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group —Henderson County, North Carolina
SANSTONE_BOUNDARY
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff.- None Specified
Tie -break Rule: Higher
OSl)A Natural Resources Web Soil Survey 4/3/2020
Conservation Service National Cooperative Soil Survey Page 4 of 4

aind Ev aV, ation by Land Experts
July 21, 2020
Brooks Engineering Associates, PA
17 Arlington St.
Asheville, NC 28801
Attention: Mark Brooks, PE
Regarding: Report of Findings
Storm Water -Soil Evaluation
LRM Project # 70120
Dear Mr. Brooks:
Land Resource Management, PLLC (LRM) appreciates the opportunity to provide this Report of
Findings. The subject site is a proposed Storm Water Basin utilized to infiltrate storm water on
Henderson County, NC Tax ID 9632-48-7869. The background and findings are discussed below.
Background
The purpose of the study is to access the sites suitability for storm water infiltration, by providing site
specific soils information. One test pit was excavated and described in the center of the proposed
basin. The purpose of the test pit was to described the soil profile and identify if a Seasonal High -
Water Table (SHWT) existed beneath the basin.
Findings
The placement of the test pits was coordinated with Brooks Engineering Associates, PA (BEA) to be
representative of the proposed Storm Water Basin. The soil was described to a depth of 75 inches
beneath the ground surface. The soil description identified a Residual soil with a clay loam texture.
No SHWT was observed in the test pit. The full soil profile description is provided as Enclosure 1.
LRM appreciates the opportunity to provide this Report of Findings. Please do not hesitate to call
with any questions or concerns.
Sincerely,
Walker Ferguson, LSS
President, Land Resource Management, PLLC
Enclosure:
1) Soil Profile Description

LAND RESOURCE MANAGEMENT
--- Land Evaluation by Land Experts --
po T. sQX rs251. ASr,aVtLl.r go 21�415 11 are 2$1.16sj 11 WWW I.ANEMA.�QatA
r--Kf/ AAIM KI ARAC. in_. e�­ f__
PIT: 5r,-wz wp,Tea
LOT:
COUNTY: H&DERSorJ
DATE: �i Z1 2o
PERCENT SLOPE Rufe .1940 : I Z°/D
CLAY MINERALOGY Rule .1941 : N/A SE MX EX
LANDSCAPE POSITION Rule .1940 : SltE Sw*
SOIL DEPTH Rule .1943 : 6e
TOPOGRAPHY Rule .1940 . Uniform
�1
RESTRICTIVE HORIZON Rule .1944 : i % s
PARENT MATERIAL: AL CO RE A/C AIR C/R
SEASONAL HIGH WATER TABLE Rule .1942 : > 7s
SOIL GROUP Rule .1955 : 4
TYPE OF WATER TABLE (Rule. 942:
SAPROLITE GROUP Rule .1956 :
CLASSIFICATION Rule .1 948ZUS
NOTES:
RECLASSIFIED Rule .1 948. N/ PS
inches = trench depth
inches = slope correction soil depth
inches = regulated soil depth
+ inches = regulated saprolite depth
inches total depth needed
Calculated for
t*
FIELD ESTIMATES
HORIZON
DEPTH
MOIST COLOR
MATRIX MOTTLES TEXTURE STRUCT- CONSIST
CLAY
L I HR
AEROBIC
CONV.
URE -ENCE
DRIP
(Rule
.1939
(inches)
(Rule .1941) (Rule(Rule
1941)
(Rule
.1969)
(Rule
.1955)
X7
ScL
IM58y
Ilrt
ZSclo
0=35
Q5
J 1
0 i(GI t1
J 1, �`I�
r
l._L
ZT
9111-391,
Z: k,4
Bc°
3g!�Z`t
��Sy,�S�s
Mcs
IM,�_
F�
0,q
5j6ti7S-PA
n
LRM- NO Revised 10/2012
MCA � Multicolored Alluvium
MCC = Multicolored colluvium
MCS = Multicolored saprolite
LTAR = Long Term Acceptance Rate in
gallons per square foot per day
RF = Rock fragments
DESCRIBED BY: CHECKED BY: W 6F
RLHB = Restrictive layer-- Hard bedrock
RLWB = Restrictive layer —Weathered bedrock
SBRF = Stopped by rock fragments

U.S. Fish and Wildlife Service
InventoryNational Wetlands
Sanstone Office & Storage Expansion
July 15, 2�2� This map is for general reference only. The US Fish and Wildlife
y Service is not responsible for the accuracy or currentness of the
Wetlands base data shown on this map. All wetlands related data should
Freshwater Emergent Wetland Lake be used in accordance with the layer metadata found on the
Wetlands Mapper web site.
Estuarine and Marine Deepwater Freshwater Forested/Shrub Wetland % Other
Estuarine and Marine Wetland Ej Freshwater Pond 11 Riverine
National Wetlands Inventory (NWI)
This page was produced by the NWI mapper

Appendix "2"

Hydraulic Grade Line Computations- 25 YEAR
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)
(ftls)
(ft)
(ft)
N
(ft)
(ft)
(ft)
(ft)
(sgft)
(ft/s)
(ft)
(ft)
N
N
(ft)
(K)
(ft)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
1
30
17.25
2181.00
2181.98
0.98
1.77
9.73
1.47
2183.45
0.00
23.73
2181.29
2182.27
0.98
1.77
9.73
1.47
2183.45
0.00
1.21
0.29
0.00
0.51
2
30
14.99
2181.29
2182.90
1.61
3.33
5.78
0.52
2183.21
0.17
24.00
2181.65
2182.96
1.31
2.59
4.50
0.31
2183.21
0.33
0.25
0.06
0.00
0.35
3
24
11.95
2182.15
2183.48
1.33
2.23
5.83
0.53
2183.93
0.32
166.03
2183.81
2185.05
1.24
2.05
5.37
0.45
2183.93
0.40
0.36
0.60
0.00
0.30
4
24
6.66
2183.81
2185.39
1.58
2.67
4.75
0.35
2185.49
0.07
202.98
2189.59
2190.50
0.91
1.40
2.50
0.10
2185.49
0.34
0.20
0.41
0.00
0.12
5
24
5.21
2189.59
2190.68
1.09
1.76
4.40
0.30
2190.82
0.11
100.90
2198.32
2199.12
0.80
1.18
2.96
0.14
2190.82
0.33
0.22
0.22
0.00
0.00
6
18
4.76
2200.33
2200.70
0.37
0.34
13.86
2.99
2203.69
0.00
88.86
2207.44
2207.81
0.37
0.34
13.86
2.99
2203.69
0.00
7.93
7.05
0.00
1.43
7
18
4.03
2209.31
2210.13
0.82
0.99
4.42
0.30
2210.39
0.31
101.05
2215.37
2216.14
0.77
0.91
4.07
0.26
2210.39
0.39
0.35
0.35
0.00
0.09
8
18
2.98
2215.37
2216.27
0.89
1.10
4.01
0.25
2216.38
0.13
120.51
2216.58
2217.23
0.66
0.74
2.72
0.11
2216.38
0.37
0.25
0.30
0.00
0.06
9
18
2.70
2216.58
2217.35
0.77
0.91
3.89
0.23
2217.48
0.17
55.12
2217.13
2217.75
0.62
0.69
2.96
0.14
2217.48
0.36
0.27
0.15
0.00
0.05
10
18
2.54
2217.13
2217.86
0.73
0.85
3.82
0.23
2218.00
0.18
67.16
2217.80
2218.40
0.60
0.67
2.99
0.14
2218.00
0.36
0.27
0.18
0.00
0.10
11
18
1.91
2217.80
2218.53
0.73
0.85
3.50
0.19
2218.61
0.10
53.81
2218.34
2218.86
0.52
0.55
2.24
0.08
2218.61
0.35
0.23
0.12
0.00
0.12
12
18
1.30
2218.34
2219.00
0.66
0.74
3.14
0.15
2219.04
0.07
69.83
2219.04
2219.46
0.43
0.41
1.75
0.05
2219.04
0.35
0.21
0.15
0.00
0.03
13
18
0.43
2220.48
2220.64
0.16
0.10
4.18
0.27
2220.91
0.00
24.00
2220.96
2221.12
0.16
0.10
4.18
0.27
2220.91
0.00
1.98
0.48
0.00
0.05
14
18
0.51
2212.95
2213.13
0.18
0.12
4.39
0.30
2213.43
0.00
23.86
2213.43
2213.60
0.18
0.12
4.39
0.30
2213.43
0.00
1.99
0.47
0.00
0.06
15
18
0.50
2191.17
2191.35
0.17
0.11
4.37
0.30
2191.64
0.00
23.92
2191.65
2191.82
0.17
0.11
4.37
0.30
2191.64
0.00
1.99
0.47
0.00
0.06
16
18
2.21
2184.43
2185.38
0.95
1.18
3.66
0.21
2185.43
0.06
44.04
2185.31
2185.87
0.56
0.60
1.88
0.05
2185.43
0.35
0.21
0.09
0.00
0.04
Project File: MILLS RIVER 25-YR FIXED Number of lines: 16 Run Date: 07/14/2020
Notes:

P 0 IN ID IR: 1l P lRAIP 0 U 1f 11 FT
ST1
4
3 ro�
Outlet T' W = Do �' to
Pipe
I
diameter (Do)
L, —A
. . . . . . T ilwater.- 0.5DO
0 25-YEAR FLOW= 17.25CFS
0 PIPE SIZE= 301N.
0 RIP RAP PAD PARAMETERS
0 L= 14 FT
0 W= 18 FT
0 d50= 0.5
0 depth= 14 in 90
80
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full, minimum tailwator condition (Tw < 0.5 diameter),
Rev. 12/93 8,063

P 0 IN ID IR: 1lP lRAIP 0 U 1f IL..IFT
BMP#1
us=
4
3 0
Outlet W = Do La
pipe
diameter (Do)
La --A
----- A
T 'I te_L:< 0. 5 Do
0 25-YEAR FLOW= 13.84CFS
0 PIPE SIZE= 181N.
0 RIP RAP PAD PARAMETERS
0 L= 10 FT
0 W= 12 FT
* d50= 0.3
* deDth=12 in
0n
60
50
I i I I I II --*J- �__-L I I - 1 0
3 5 10 20 so 100 200 500 1000
Discharge (0/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet prolocfion protection from a round pipe flowing full, minimum tailwator condition (Tw < 0.5 diameter).
Rev, 12193 8.063

Appendix " 3"

Simple Method for RO Volume
BMP #1
Rv = 0.05 + 0.9 * la
DV = 3630 * Rd * Rv * A
Rv
0.3509
la
0.3343
Rd (in)
1.0
A (ac)
4.41
Design Vol (CF)
Design Vol (acre-ft)
5,622
0.129
Temporary Pool Surface Area for Bioretention
Max. Allowable Ponding Depth (ft)
BMP #1
1.0
Min. Required Surface Area (SF) 5,622
Provided Surface Area at bottom (SF) 5,873
Provided Surface Area 1 ft above bottom (SF) 6,809
Calculated Ponding Depth for RO Volume (ft) 0.89 --> Set Peak attentuation at 12"

Underdrain Sizing (Per NCDEQ Stormwater Design Manual Sec A-S)
Determine Flow Rate
Surface Area at top of Media 5873 SF
Hydraulic Conductivity of Media (5 in/hr) 0.000116 ft/s
Flow Rate 0.680 cfs
Apply Safety Factor (2-10 times max. flow) 2.00
Design Q 1.36 cfs
Calculate the Diameter of a Single Pipe needed
to carry all the water, D 8.94 in where,
Per Section A-5 (Table 2) use 3 - 6" pipes for the underdrain system.
n `C
n 3/8
D=16
s
D = diameter, in inches
n = Manning's roughness coefficent (0.011)
s = slope, ft/ft (0.005 ft/ft)
Q = discharge, in cfs

IWS Drawdown Time Calculation
Use the following equations to determine the necessary orifice size to
achieve a drawdown time between 2 - 5 days.
DV
Q = t
Q=CdxAx �2gxn1)
3
Set Drawdown Time = 2.0 days
---) A =
DVIt
Cd x r2gx (H°1 )
3
where:
DV = 5,622 Design Volume calculated using the simple method (CF)
t = 172,800 Drawdown Time (sec)
Q = 0.0325 IDischarge rate (CFS)
Cd = 0.6 orifice coefficient
g = 32.2 acceleration of gravity (ft/seC2)
Ho= 1.00 maximum head (ft), divide by three to model diminishing head
A = 0.01170 Cross sectional Area of the orifice (ft)
Solve for orifice diameter (A = 0.25nD2)
D = 1.902 Calculated Orifice Diameter (in)
Specify orifice size, D = 1.90 in (Round down to nearest tenth)

E1 P1 P5
Existing Basin 1 Propose t
o BMP P2 Proposed Basin 2
E2 P6
P3 B P Bypass
Existing Basin 2 \,, Proposed Basin 3
BMP1 u
E3 P4
Existing Basin 3 Total Proposed Basin 1
Subcat Reach on Link Routing Diagram for Sanstone
Prepared by Brooks EA, Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HvdroCAD® 10.00-24 s/n 05122 © 2018 HvdroCAD Software Solutions LLC Paae 2
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment E1: Existing Basin 1 Runoff Area=138,603 sf 0.00% Impervious Runoff Depth>0.57"
Flow Length=513' Tc=17.1 min CN=69 Runoff=2.16 cfs 0.152 of
Subcatchment E2: Existing Basin 2 Runoff Area=94,309 sf 0.00% Impervious Runoff Depth>0.22"
Flow Length=515' Tc=15.7 min CN=58 Runoff=0.33 cfs 0.039 of
Subcatchment E3: Existing Basin 3 Runoff Area=43,914 sf 0.00% Impervious Runoff Depth>0.15"
Flow Length=217' Tc=12.1 min CN=55 Runoff=0.08 cfs 0.013 of
Subcatchment P1: Proposed to BMP Runoff Area=192,269 sf 33.43% Impervious Runoff Depth>0.79"
Flow Length=649' Tc=16.9 min CN=74 Runoff=4.48 cfs 0.292 of
Subcatchment P2: BMP Bypass Runoff Area=40,018 sf 0.80% Impervious Runoff Depth>0.80"
Flow Length=345' Tc=10.1 min CN=74 Runoff=1.19 cfs 0.061 of
Subcatchment P5: Proposed Basin 2 Runoff Area=34,170 sf 0.00% Impervious Runoff Depth>0.27"
Flow Length=379' Tc=13.5 min CN=60 Runoff=0.20 cfs 0.018 of
Subcatchment P6: Proposed Basin 3 Runoff Area=11,791 sf 3.66% Impervious Runoff Depth>0.30"
Flow Length=161' Tc=10.6 min CN=61 Runoff=0.09 cfs 0.007 of
Pond P3: BMP 1 Peak Elev=2,182.19' Storage=7,672 cf Inflow=4.48 cfs 0.292 of
Outflow=0.33 cfs 0.129 of
Link P4: Total Proposed Basin 1 Inflow=1.19 cfs 0.190 of
Primary=1.19 cfs 0.190 of
Total Runoff Area = 12.743 ac Runoff Volume = 0.582 of Average Runoff Depth = 0.55"
88.29% Pervious = 11.250 ac 11.71% Impervious = 1.493 ac

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 3
Summary for Subcatchment E1: Existing Basin 1
Runoff = 2.16 cfs @ 12.12 hrs, Volume= 0.152 af, Depth> 0.57"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (sf) CN Description
20,567
61
>75% Grass cover, Good, HSG B
15,093
61
>75% Grass cover, Good, HSG B, Offsite
92,037
74
>75% Grass cover, Good, HSG C
23
74
>75% Grass cover, Good, HSG C, Offsite
10,883
55
Woods, Good, HSG B
138,603
69
Weighted Average
138,603
100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.4
100
0.0691
0.13
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
4.7
413
0.0850
1.46
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
17.1 513 Total
w
0
LL
Subcatchment E1: Existing Basin 1
Hydrograph
2.16 cfs
1y
r
Rai
fall
2.
7"
RunoffAr
a=
38,603
sf
Runoff
Vo l
u m
0.152
of
Ru�nof
Deh
pt
0.
7"
Tc
17
1 rr
in
N=69
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
El RunoffIll

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 4
Summary for Subcatchment E2: Existing Basin 2
Runoff = 0.33 cfs @ 12.15 hrs, Volume= 0.039 af, Depth> 0.22"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (sf) CN Description
544
61
>75% Grass cover, Good, HSG B
4,899
74
>75% Grass cover, Good, HSG C
79,315
55
Woods, Good, HSG B
9,551
70
Woods, Good, HSG C
94,309
58
Weighted Average
94,309
100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
11.0
100
0.0929
0.15
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
4.7
415
0.0875
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
15.7 515 Total
0.36
0.34
0.32
0.3
0.28
0.26
0.24
0.22
0.2
3 0.18
0
LL 0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
Subcatchment E2: Existing Basin 2
Hydrograph
_______________
-_____
_______
I______
-_____
___fffflMMM
_MMMMMM
-_____-
______-
-_MM===M
-EM7
M
MM
-_____.
-M_TiTil�MMM"M
i i
• �
-_____.
______.
-MMUMMI�MOM
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 5
Summary for Subcatchment E3: Existing Basin 3
Runoff = 0.08 cfs @ 12.12 hrs, Volume= 0.013 af, Depth> 0.15"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (so CN Description
43,914 55 Woods, Good, HSG B
43,914 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.8
100
0.0987
0.16
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
1.3
117
0.0926
1.52
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
12.1 217 Total
0
0
0
N
0
3
0
LL 0
0
0
0
Subcatchment E3: Existing Basin 3
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p� Runoff

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 6
Summary for Subcatchment P1: Proposed to BMP
Runoff = 4.48 cfs @ 12.11 hrs, Volume= 0.292 af, Depth> 0.79"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (sf) CN Description
12,953
98
Impervious - Buildings
3,177
98
Impervious - Sidewalk
38,203
98
Impervious - Pavement, Curb
833
98
Impervious - Pavement, Curb - Offsite
9,100
98
Impervious - Future Storage
44,737
61
>75% Grass cover, Good, HSG B
15,093
61
>75% Grass cover, Good, HSG B - Offsite
30,204
74
>75% Grass cover, Good, HSG C
1,005
74
>75% Grass cover, Good, HSG C - Offsite
36,964
55
Woods, Good, HSG B
192,269
74
Weighted Average
128,003
66.57% Pervious Area
64,266
33.43% Impervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.8
100
0.0640
0.13
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
2.3
236
0.1160
1.70
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.8
313
0.0210
2.94
Shallow Concentrated Flow, Curb Flow
Paved Kv= 20.3 fps
16.9 649 Total

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 7
N
0
LL
Subcatchment P1: Proposed to BMP
Hydrograph
4.48 cfs
Ty
e 124
h r
1
yr
ai
fall
2.
7"
Runof
Ar
a=
92,269
sf
j
u
o
o
um
a
j
Runof
Depth
0.
9"
_
Tc
16
9 rr
in
N=74
10 11 12 13 14 15 16 17 18 19 20
Time (hours)
El Runoff

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment P2: BMP Bypass
Runoff = 1.19 cfs @ 12.03 hrs, Volume= 0.061 af, Depth> 0.80"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (so CN Description
39,696 74 >75% Grass cover, Good, HSG C
322 98 Impervious - Sidewalk
40,018 74 Weighted Average
39,696 99.20% Pervious Area
322 0.80% Impervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
7.5
100
0.0877
0.22
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
2.6
245
0.0515
1.59
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
10.1 345 Total
Subcatchment P2: BMP Bypass
Hydrograph
1.19 cfs
Ty
e 124
h r
.
11
Runoff
rea
40,
18
sf
Runoff
Vo I
u m
=0.061
of
Runoff
Depth
0.
0"
How
Le
gt
=3
5'
Tc
10
1
in
N=74
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment P& Proposed Basin 2
Runoff = 0.20 cfs @ 12.11 hrs, Volume= 0.018 af, Depth> 0.27"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (sf) CN Description
5,294
61
>75% Grass cover, Good, HSG B
3,397
74
>75% Grass cover, Good, HSG C
19,464
55
Woods, Good, HSG B
6,015
70
Woods, Good, HSG C
34,170
60
Weighted Average
34,170
100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.0
100
0.1191
0.17
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
3.5
279
0.0724
1.35
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
13.5 379 Total
0.22
0.21
0.2
0.19
0.18
0.17
0.16
0.15
0.14
0.13
0.12
3 0.11
° 0.1
LL 0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Subcatchment P& Proposed Basin 2
Hydrograph
iMMMMMM�_
����w�w■�
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment P6: Proposed Basin 3
Runoff = 0.09 cfs @ 12.06 hrs, Volume= 0.007 af, Depth> 0.30"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-yr Rainfall=2.97"
Area (sf) CN Description
431 98 Impervious - Pavement, Curb
8,479 61 >75% Grass cover, Good, HSG B
2,881 55 Woods, Good, HSG B
11,791 61 Weighted Average
11,360 96.34% Pervious Area
431 3.66% Impervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.6
100
0.0475
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
1.0
61
0.0205
1.00
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.1
0.095
0.09
0.085
0.08
0.075
0.07
0.065
H 0.06
0.055
0 0.05
LL 0.045
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
5
Subcatchment P6: Proposed Basin 3
Hydrograph
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 11
Summary for Pond P3: BMP 1
Inflow Area = 4.414 ac, 33.43% Impervious, Inflow Depth > 0.79" for 1-yr event
Inflow = 4.48 cfs @ 12.11 hrs, Volume= 0.292 of
Outflow = 0.33 cfs @ 13.79 hrs, Volume= 0.129 af, Atten= 93%, Lag= 100.7 min
Primary = 0.33 cfs @ 13.79 hrs, Volume= 0.129 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 2,182.19' @ 13.79 hrs Surf.Area= 7,002 sf Storage= 7,672 cf
Plug -Flow detention time= 224.1 min calculated for 0.128 of (44% of inflow)
Center -of -Mass det. time= 131.0 min ( 951.2 - 820.2 )
Volume Invert
#1 2,181.00'
UV01
Description
21,991 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area
Inc.Store
Cum.Store
(feet)
(sq-ft)
(cubic -feet)
(cubic -feet)
2,181.00
5,873
0
0
2,182.00
6,809
6,341
6,341
2,183.00
7,809
7,309
13,650
2,184.00
8,873
8,341
21,991
Device Routina Invert Outlet Devices
#1 Primary 2,177.75' 18.0" Round Culvert
L= 42.0' CPP, projecting, no headwall, Ke= 0.900
Inlet / Outlet Invert= 2,177.75' / 2,177.00' S= 0.0179'/' Cc= 0.900
n= 0.011 HDPE, Flow Area= 1.77 sf
#2 Primary 2,182.25' 5.0' long x 18.5' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
#3 Device 1 2,182.00' 48.0" Vert. Orifice/Grate C= 0.600
Primary OutFlow Max=0.33 cfs @ 13.79 hrs HW=2,182.19' (Free Discharge)
1=Culvert (Passes 0.33 cfs of 12.91 cfs potential flow)
L3=Orifice/Grate (Orifice Controls 0.33 cfs @ 1.49 fps)
2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

Sanstone
Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 12
N
U
Pond P3: BMP 1
Hyd rog raph
5...
4.48 cfs
nfl
w
Ar
a=
.4
4 ac
Pak
Elev=
2.199
4:
,1
Strae7
72
cf
3...
2...
0.33 cfs
, ,, ,,%ifs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
� Inflow
p Primary

Sanstone Type 1124-hr 1-yr Rainfall=2.97"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 13
Summary for Link P4: Total Proposed Basin 1
Inflow Area = 5.333 ac, 27.81% Impervious, Inflow Depth > 0.43" for 1-yr event
Inflow = 1.19 cfs @ 12.03 hrs, Volume= 0.190 of
Primary = 1.19 cfs @ 12.03 hrs, Volume= 0.190 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
M
Link P4: Total Proposed Basin 1
Hyd rog raph
1.19 cfs
1.19cfs
nfl
w
Ar
a=
.3
3 ac
anion
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
� Inflow
p Primary

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HvdroCAD® 10.00-24 s/n 05122 © 2018 HvdroCAD Software Solutions LLC Paae 14
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment E1: Existing Basin 1 Runoff Area=138,603 sf 0.00% Impervious Runoff Depth>2.42"
Flow Length=513' Tc=17.1 min CN=69 Runoff=10.09 cfs 0.641 of
Subcatchment E2: Existing Basin 2 Runoff Area=94,309 sf 0.00% Impervious Runoff Depth>1.52"
Flow Length=515' Tc=15.7 min CN=58 Runoff=4.35 cfs 0.275 of
Subcatchment E3: Existing Basin 3 Runoff Area=43,914 sf 0.00% Impervious Runoff Depth>1.31"
Flow Length=217' Tc=12.1 min CN=55 Runoff=1.94 cfs 0.110 of
Subcatchment P1: Proposed to BMP Runoff Area=192,269 sf 33.43% Impervious Runoff Depth>2.87"
Flow Length=649' Tc=16.9 min CN=74 Runoff=16.68 cfs 1.054 of
Subcatchment P2: BMP Bypass Runoff Area=40,018 sf 0.80% Impervious Runoff Depth>2.87"
Flow Length=345' Tc=10.1 min CN=74 Runoff=4.32 cfs 0.220 of
Subcatchment P5: Proposed Basin 2 Runoff Area=34,170 sf 0.00% Impervious Runoff Depth>1.68"
Flow Length=379' Tc=13.5 min CN=60 Runoff=1.90 cfs 0.110 of
Subcatchment P6: Proposed Basin 3 Runoff Area=11,791 sf 3.66% Impervious Runoff Depth>1.76"
Flow Length=161' Tc=10.6 min CN=61 Runoff=0.77 cfs 0.040 of
Pond P3: BMP 1 Peak Elev=2,182.90' Storage=12,865 cf Inflow=16.68 cfs 1.054 of
Outflow=13.84 cfs 0.878 of
Link P4: Total Proposed Basin 1 Inflow=15.60 cfs 1.098 of
Primary=15.60 cfs 1.098 of
Total Runoff Area = 12.743 ac Runoff Volume = 2.449 of Average Runoff Depth = 2.31"
88.29% Pervious = 11.250 ac 11.71% Impervious = 1.493 ac

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 15
Summary for Subcatchment E1: Existing Basin 1
Runoff = 10.09 cfs @ 12.10 hrs, Volume= 0.641 af, Depth> 2.42"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (sf) CN Description
20,567
61
>75% Grass cover, Good, HSG B
15,093
61
>75% Grass cover, Good, HSG B, Offsite
92,037
74
>75% Grass cover, Good, HSG C
23
74
>75% Grass cover, Good, HSG C, Offsite
10,883
55
Woods, Good, HSG B
138,603
69
Weighted Average
138,603
100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.4
100
0.0691
0.13
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
4.7
413
0.0850
1.46
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
17.1 513 Total
7
6
LL 5
Subcatchment E1: Existing Basin 1
Hydrograph
0.09 cfs
Ty
a 124
h r
j
25
yr lRair
fall
5.
2"
RL
noff
Ar
a=
38,603
sf
Ru
off
Vo
u m
=0.641
of
R
not
D
pth
2.
2"
'lomf
Lengt
=5
3'
T
=17.1
min
j
=
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p� Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 16
Summary for Subcatchment E2: Existing Basin 2
Runoff = 4.35 cfs @ 12.09 hrs, Volume= 0.275 af, Depth> 1.52"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (sf) CN Description
544
61
>75% Grass cover, Good, HSG B
4,899
74
>75% Grass cover, Good, HSG C
79,315
55
Woods, Good, HSG B
9,551
70
Woods, Good, HSG C
94,309
58
Weighted Average
94,309
100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
11.0
100
0.0929
0.15
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
4.7
415
0.0875
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
15.7 515 Total
N
3
0
LL
Subcatchment E2: Existing Basin 2
Hydrograph
4.35 cfs
j
25
yr
Rair
fall
5.
2
Runoff
rea
94,
09
Sf
j
Ru
off
Vol
u m
=0.275
of
Runof
Depth
1.
2"
Tc
15
7 rr
in
N=58
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 17
Summary for Subcatchment E3: Existing Basin 3
Runoff = 1.94 cfs @ 12.06 hrs, Volume= 0.110 af, Depth> 1.31"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (so CN Description
43,914 55 Woods, Good, HSG B
43,914 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.8
100
0.0987
0.16
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
1.3
117
0.0926
1.52
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
12.1 217 Total
w
0
LL
Subcatchment E3: Existing Basin 3
Hydrograph
1.94 cfs
Ty
a 124
h r
25
yr
Rair
fall
5.
2"
Runoff
rea
43,
14
sf
Runoff
Vo l
u m
=0.110
of
jRunoff
Depth
1.
1"
Flow
Le
gt
=2
7'
Tc
12
1 rr
in
N=55
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p� Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 18
Summary for Subcatchment P1: Proposed to BMP
Runoff = 16.68 cfs @ 12.09 hrs, Volume= 1.054 af, Depth> 2.87"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (sf) CN Description
12,953
98
Impervious - Buildings
3,177
98
Impervious - Sidewalk
38,203
98
Impervious - Pavement, Curb
833
98
Impervious - Pavement, Curb - Offsite
9,100
98
Impervious - Future Storage
44,737
61
>75% Grass cover, Good, HSG B
15,093
61
>75% Grass cover, Good, HSG B - Offsite
30,204
74
>75% Grass cover, Good, HSG C
1,005
74
>75% Grass cover, Good, HSG C - Offsite
36,964
55
Woods, Good, HSG B
192,269
74
Weighted Average
128,003
66.57% Pervious Area
64,266
33.43% Impervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.8
100
0.0640
0.13
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
2.3
236
0.1160
1.70
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.8
313
0.0210
2.94
Shallow Concentrated Flow, Curb Flow
Paved Kv= 20.3 fps
16.9 649 Total

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 19
18
17
16
15-:
14:
13-:
12-'
11!!!
N
u 10:
o
LL
7.::
6.i!!
5.i:
4.::
3:
2.i!!
0!!!
5
Subcatchment P1: Proposed to BMP
Hydrograph
i��wwww�ww�www�ww
______■
I______■
-Mwwwm�.M
-MQ=LQ=iMlwlWLw
-_____■
-_"M"=wM
______■
-_MI=MN!UfliiXA
______■
-_____■
I______■
I_____
-___�WRMM
I .___MMwM
1 .____M�.
_______
�,pE"
_____
_______
_______
VA�
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p� Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 20
Summary for Subcatchment P2: BMP Bypass
Runoff = 4.32 cfs @ 12.02 hrs, Volume= 0.220 af, Depth> 2.87"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (so CN Description
39,696 74 >75% Grass cover, Good, HSG C
322 98 Impervious - Sidewalk
40,018 74 Weighted Average
39,696 99.20% Pervious Area
322 0.80% Impervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
7.5
100
0.0877
0.22
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
2.6
245
0.0515
1.59
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
10.1 345 Total
N
3
0
LL
Subcatchment P2: BMP Bypass
Hydrograph
4.32 cfs
25
yr
Rai
fall
5.
2"
Runoff
Area
40,018
sf
j
Runoff
Vo I
u rn
=0.220
of
Runoff
Depth
2.
7"
Tc
10
1 rnin
N=74
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 21
Summary for Subcatchment P& Proposed Basin 2
Runoff = 1.90 cfs @ 12.07 hrs, Volume= 0.110 af, Depth> 1.68"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (sf) CN Description
5,294
61
>75% Grass cover, Good, HSG B
3,397
74
>75% Grass cover, Good, HSG C
19,464
55
Woods, Good, HSG B
6,015
70
Woods, Good, HSG C
34,170
60
Weighted Average
34,170
100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.0
100
0.1191
0.17
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
3.5
279
0.0724
1.35
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
13.5 379 Total
Subcatchment P& Proposed Basin 2
Hydrograph
1.90 cfs
Ty
e 124
h r
j
25
yr
Rair
fall
5.
2"
Runoff
Area
34,170
sf
Runoff
Volum
0.110
of
Runoff
De
th
1.
8"
Flow
Le
gt
=3
9'
Tc
135
rr
_in
N=
30
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 22
Summary for Subcatchment P6: Proposed Basin 3
Runoff = 0.77 cfs @ 12.03 hrs, Volume= 0.040 af, Depth> 1.76"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25-yr Rainfall=5.92"
Area (sf) CN Description
431 98 Impervious - Pavement, Curb
8,479 61 >75% Grass cover, Good, HSG B
2,881 55 Woods, Good, HSG B
11,791 61 Weighted Average
11,360 96.34% Pervious Area
431 3.66% Impervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.6
100
0.0475
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
1.0
61
0.0205
1.00
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.85 :,
0.8 :i
0.75
0.7.:
0.65:
0.6 :i
0.55
0.5
N
0.45
0 0.4
LL
0.35 iii
0.3
0.25
0.2 :i
0.15 iii
0.1
0.05
0.:ii
5
Subcatchment P6: Proposed Basin 3
Hydrograph
®---------------
------��-------
-----
------■
�---MMMM
--MMWMMM
------■
------■
--M�"�""M
-©�.I.WLJ!
MM7
9�110M
-_____■
i7Til�
------■
--���:T.'S
7 SSG
!�
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
p Runoff

Sanstone Type/1 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 23
Summary for Pond P3: BMP 1
Inflow Area = 4.414 ac, 33.43% Impervious, Inflow Depth > 2.87" for 25-yr event
Inflow = 16.68 cfs @ 12.09 hrs, Volume= 1.054 of
Outflow = 13.84 cfs @ 12.18 hrs, Volume= 0.878 af, Atten= 17%, Lag= 5.1 min
Primary = 13.84 cfs @ 12.18 hrs, Volume= 0.878 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 2,182.90' @ 12.18 hrs Surf.Area= 7,708 sf Storage= 12,865 cf
Plug -Flow detention time= 77.9 min calculated for 0.875 of (83% of inflow)
Center -of -Mass det. time= 30.2 min ( 823.6 - 793.4 )
Volume Invert
#1 2,181.00'
UV01
Description
21,991 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area
Inc.Store
Cum.Store
(feet)
(sq-ft)
(cubic -feet)
(cubic -feet)
2,181.00
5,873
0
0
2,182.00
6,809
6,341
6,341
2,183.00
7,809
7,309
13,650
2,184.00
8,873
8,341
21,991
Device Routina Invert Outlet Devices
#1 Primary 2,177.75' 18.0" Round Culvert
L= 42.0' CPP, projecting, no headwall, Ke= 0.900
Inlet / Outlet Invert= 2,177.75' / 2,177.00' S= 0.0179'/' Cc= 0.900
n= 0.011 HDPE, Flow Area= 1.77 sf
#2 Primary 2,182.25' 5.0' long x 18.5' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
#3 Device 1 2,182.00' 48.0" Vert. Orifice/Grate C= 0.600
Primary OutFlow Max=13.65 cfs @ 12.18 hrs HW=2,182.89' (Free Discharge)
1=Culvert (Passes 6.73 cfs of 14.08 cfs potential flow)
L3=Orifice/Grate (Orifice Controls 6.73 cfs @ 3.22 fps)
2=Broad-Crested Rectangular Weir (Weir Controls 6.92 cfs @ 2.15 fps)

Sanstone Type // 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 24
1E
17
1E
1E
14
1�
12
11
N
1C
3 E
0
LL E
Pond P3: BMP 1
Hyd rog raph
M i
NO",
FI t•TE'
IE, li
L FTM
IMMMMM��
■ 1�
3L�J
C��fl
t�JL�
=====�®
=aolt-
MMMMMM=
Le laame
&AAM
MMMMMM=
______
---------------
■��
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
� Inflow
p Primary

Sanstone Type 11 24-hr 25-yr Rainfall=5.92"
Prepared by Brooks EA Printed 8/28/2020
HydroCAD® 10.00-24 s/n 05122 © 2018 HydroCAD Software Solutions LLC Page 25
Summary for Link P4: Total Proposed Basin 1
Inflow Area = 5.333 ac, 27.81% Impervious, Inflow Depth > 2.47" for 25-yr event
Inflow = 15.60 cfs @ 12.16 hrs, Volume= 1.098 of
Primary = 15.60 cfs @ 12.16 hrs, Volume= 1.098 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
17
1E
1E
14
1�
12
11
H 1c
U c
o E
LL
I
Link P4: Total Proposed Basin 1
Hyd rog raph
_____�'
-______
-___
-_____,
MMMMM`t`FM
______-
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
� Inflow
p� Primary

Appendix "4"

sr
Sanstone Office & Storage Expansion
SKIMMER SEDIMENT BASIN SIZING CHART
Basin
Drainage Area 1 Flow Calcs.:
Min. Size Calcs.:
Basin Storage Dimensions:
#:
Drainage area (ac.)
Weighted
C:
10yr
intensit :
50yr
intensit :
Q10
cfs :
Q50
(cfs):
Min. Surface
Area ft2
Min. Volume
ft3
Bottom
Elevation:
1
Length (ft):
Width (ft.):
Area ftZ :
( )
Depth
(ft.):
Volume
ft3 :
Total:
Disturbed:
To
Bottom:
Top:
Bottom:
1
5.10
3,10 1
0.48
7.06
1 8.87
17.37
21.82
5,644.5
5,580.0
2178:0' 1
130.0
117.0
1 78.0
65.0
1 8,873.0
1 3,,25
28,835.6
Skimmer Sediment Basin Design Notes:
1. Sediment Basins have been designed in accordance with the North Carolina Erosion
and Sediment Control Planning and Design Manual Standard (Revision number
6/06) Standard number 6.64
2. Maximum Drainage Area = 10 Acres
3. Minimum Volume = 1800 ft3 per Acre of Disturbed Area.
4. Minimum Surface Area = 325 ft2 per Q10 (cfs) of peak inflow.
5. Dewatering time is from 24 to 72 hours
6. Each basin requires 3 baffles
BRC"KS
1�
N d N E.ER1 N G AS C O C'.pAl"'Ek'�iry .
f7 As4ingtnit Street 0' Asheville, NC 7. 01 / 232-4700

sr
Basin
SpillwayCalcs.:
M
Dewatering
1
Number of
Skimmer
Skimmer
Ponding
Emergency
Emergency
Emergency
Water
Free -board
Top of
Time (hrs.):
Skimmers:
Size:
Orifice Size:
Elevation:
Spillway El.:
Spillway Dim.:
Spillway V(f/s):
Depth (ft):
(ft):
Dam El.:
1
48,houm
1
2.0 in
1.8in
1 2181.25'
1 2181.75'
11.0' X 2.0'
1 1.98
1 0.82
1 1.93
2184.0'
General Notes:
Date: 04/14/20
Calculations By: BMT
BROOKS
ENO, dNEERING ASSOCpAl ES
IlMingtoafteet I Asheville, NCMOI / 820-232-4700

PIPE CHART PIPE CALCULATIONS
Road Pipe Road Up Down Pipe Pipe
Station Name Elevation Invert Invert Size Material Length Slope
�'
uPs[ReaM now :DESIGN FLOW RESULTS OUTLET PROTECTION CALCS
Upstream I Total iFlowDepthl Velocity I 605tone SUe I Apron Thickness Pad Length Pad Width
10+20 B 2224.02220.5' 2220.0' 18.0 m I H DPE 64 ft ,, 7 <
2,187 sF
0.30 1
5 min
S W2 I 0.75 cfs I 0.86 cfs I 3 6 in 1 3.6 fps 6 in B In 10 ff 15 ff

7/14/2020
ECMDS 7.0
I��� NORT f
AMERICAN
SPILLWAY ANALYSIS
> > > BMP Spillway
North American Green
5401 St. Wendel -Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
> Fax [phone]
www.nagreen.com
ECMDS v7.0
Name
BMP Spillway
Discharge
6.92 CFS - DISCHARGE OVER SPILLWAY PER 25-YEAR HYDROCAD REPORT
Peak Flow Period
24
Channel Slope
0.5
Channel Bottom Width 5
Low Flow Liner
Retardence Class
C 6-12 in
Vegetation Type
Bunch Type
Vegetation Density
Very Good 80-95%
Soil Type
Loam (MH)
P300 - Class C
- Bunch Type - Very Good 80-95%
Normal
Permissible
Permissible
Calculated
Safety
Staple
Phase
Reach
Discharge
Velocity
Mannings IN
Depth
Shear Stress
Shear Stress
Factor
Pattern
P300
Straight 6.92 cfs 10.68 ft/s
0.13 ft
0.024 2.3 Ibs/ft2
4.04 Ibs/ft2
0.57
UNSTABLE E
Unvegetated
Underlying
Straight 6.92 cfs 10.68 ft/s
0.13 ft
0.024 1.85 Ibs/ft2
3.84 Ibs/ft2
0.48
UNSTABLE E
P300 Reinforced Straight 6.92 cfs 10.07 ft/s 0.14 ft 0.027 10 Ibs/ft2 4.28 Ibs/ft2 2.34 STABLE E
Vegetation
Underlying Straight 6.92 cfs 10.07 ft/s 0.14 ft 0.027 2.3 Ibs/ft2 4.06 Ibs/ft2 0.57 UNSTABLE E
Substrate
https://ecmds.com/project/l 43924/spillway-analysis/182676/show 1 /1

IIIh e e t, ­IIE r II t,"' IIP3 0 0 " IIPeni'T ti tvt IIEroso ti (�"
The permanent erosion control blanket shall be a machine -produced
mat of 100% UV stable polypropylene fiber. The matting shall be of
consistent thickness with the synthetic fibers evenly distributed over
the entire area of the mat. The matting shall be covered on the top
side with black heavyweight UV -stabilized polypropylene netting
having ultraviolet additives to delay breakdown and an approximate
O.SO x O.SO inch (1.27 x 1.27 cm) mesh. The bottom net shall also be UV
stabilized polypropylene with a 0.63 x 0.63 inch (1.S7 x 1.S7 cm) mesh
size. The blanket shall be sewn together on IS inch (3.81 cm) centers
with non -degradable thread. All mats shall be manufactured with a
colored thread stitched along both outer edges as an overlap guide for
adjacent mats. The P300 shall meet Type SA, S13, specification
requirements established by the Erosion Control Technology Council
(ECTC) and Federal Highway Administration's (FHWA) FP-03
Section 713.18
Matrix
100% UV stable
0.7Ibs/sq yd
Polypropylene Fiber
(0.38 kg/sm)
Top: UV -stabilized Polypropylene
S Ibs/1000 sq ft
(24.4 g/sm)
Netting
Bottom: UV -stabilized Polypropylene
3 Ibs/1000 sq ft
(14.7 g/sm)
Thread
Polypropylene, UV stable
culllvU
m . m
�
Width
6.5 ft (2.0 m)
8 ft (2.44 m)
Length
108 ft (32.92 m)
112 ft (3S.14 m)
Weight ±10%
61 Ibs (27.66 I(g)
76.25 Ibs (34.59 I(g)
Area
80 sq yd (66.0 sm)
100 sq yd (83.61 sm)
Slope Gradients (S)
Slope Length (L) <- 3:1
3:1 - 2.1 > 2:1
<- 20 ft (6 m) 0.001
0.029 0.082
20-SO ft 0.036
0.060 0.086
2SO ft (1S.2 m) 0.070
0.090 0.110
Tensar International Corporation
lIU ip �f��% a
2SOO hwinds Parkway
Suite500
Alpharetta, GA 30009
map. H�
800-TENSAR-1
tensarcorp.com
Thickness
ASTM DISS2S
0.47 in.
(11.94 mm)
Resiliency
ASTM D6524
91.5%
Density
ASTM D792
0.916 g/Cm3
Mass/Unit Area
ASTM 6566
13.03 oz/sy
(443 g/m2)
UV Stability
ASTM D43SS/
90%
1000 hr
Porosity
ECTC Guidelines
95.89%
Stiffness
ASTM D1388
0.94 in -lb
(108S378 mg -cm)
Light Penetration
ASTM D6567
17.9%
438 Ibs/ft
Tensile Strength - MD
ASTM DISS67
(6.49 kN/m)
Elongation - MO
ASTM D6818
28.1%
291.9 Ibs/ft
Tensile Strength - TO
ASTM D6818
(4.32 kN/m)
Elongation - TO
ASTM D6818
26.7%
Biomass Improvement
ASTM D7322
497%
Short Duration Long Duration
Phase 1: Unvegetated
3.0 psf (144 Pa) 2.0 psf (96 Pa)
Phase 2: Partially Veg.
8.0 psf (383 Pa) 8.0 psf (383 Pa)
Phase 3: Fully Veg.
8.0 psf (383 Pa) 8.0 PSF (383 Pa)
Unvegetated Velocity
9.0 fps (2.7 m/s)
Vegetaged Velocity
16 fps (4.9 nri
Flow Depth
Manning's n
<- O.SO ft (0.1S m)
0.034
O.SO - 2.0 ft
0.034-0.020
22.0 ft (0.60 m)
0.020
'Tensar International Corporation warrants that at the time of delivery the product furnished
hereunder shall conform to the specification stated herein. Any other warranty Including
merchantability and fitness for a particular purpose, are hereby executed. If the product
does not meet specifications on this page and Tensar is notified prior to installation, Tensar
will replace the product at no cost to the customer. This product specification supersedes
all prior specifications for the product described above and is not applicable to any
products shipped priorto January 1, 2912.
©2013, Tensar International Corporation EC_RMX_MPDS_1`300_5.13