HomeMy Public PortalAboutBUTLER AV_1705.pdfCI,
COASTAL
November 15, 2018 Civil Engineering
Ms. Lisa L. Shaaf
Planning and Zoning
City of Tybee Island
403 Butler Avenue
Tybee Island, GA 31328
Re: Tybee Beach Resort -1705 Butler Avenue — P.I.N. 4-0009-02-006
Dear Ms. Shaaf,
Please find enclosed the following materials:
2 sets of plans entitled Beachview Resort and Spa, sheets C1-C3 dated 11/15/18.
We have addressed the comments received from the City Staff as follows:
Downer Davis —City Engineer
1) On the drainage calculations, markup of removed impervious areas & new impervious
areas needs a little clarification. Clearer labeling and consistent heavier lines are what is
needed. The pre and post calculations indicating no added runoff from the site is
accepted. See revised drainage report.
2) The calculations indicate that runoff will be to the rear. Even if this is existing, runoff
needs to be directed to R.O.W.'s and easements that give drainage outfall rights to this
property. Absent of legal rights of drainage outfall (other than to Butler), with changed
footprint of impervious areas and new construction, I have no basis to recommend runoff
from this project onto the property of others. The drainage scheme now includes
shallow swales to direct the water to small detention areas to assist in natural
percolation onsite, with the flow oriented towards Butler Avenue instead of
neighboring properties.
The sidewalk design slopes south to property of others, indicating new runoff direction of
flow onto property of others. This is not allowed. The cross slope of the sidewalk
directs drainage to the r/w along Butler.
3) Drainage conveyance through channels (swales, gutters, pipes, etc...) need to be
properly sized with adequate details on the plans. See attached calculations in
drainage report.
4) There is no soil and erosion control design for this project. Proper best management
practices for controlling sediment runoff from this site are required. Erosion control
design has been added to depict best management practices.
5) If this site is considered a commercial site and not "residential", onsite maneuvering of
vehicles is required. The current layout does not provide that. Parking layout approval
will be deferred per discussion between the owner and George Shaw.
30011/2 River Drive . Thunderbolt, GA 31404 . Tel 912.232.9402 . Fax 912.232.9403
tomhavens cOCORa,talCiViLcom ■ coastalcivil.com
6) The design indicates that handicapped parking requirements are met on the prior project
to the north. Supporting information is needed for that (number of total and handicapped
spaces on the prior lot. At least an exhibit is needed to show the pathway on the
adjacent site to handicapped spaces from the proposed sidewalk at the front of the
building. (I believe it connects to parking spaces and not an adjacent pathway. Also, I
the sidewalk shown in the R.O.W. at the front is routed through the van accessible aisle
for the handicapped space on the lot to the north. I do not prefer this, but I defer to
the City on this matter. Unless designed as ramps, slopes on handicapped pathways
should not exceed 2%. Per Item 5. above this will be determined at a later date.
If you have any comments or questions regarding the enclosed information, or require additional
copies of the plans, please contact me at 912-232-9402 at your convenience.
C 0 A S i A
C s V I L ENGINEERING
Hydrology Report
For
Tybee Beach Resort
PIN 4-0009-02-006
1705Butler Avenue
Tybee Island, GA
Rev 11/15/18
'. '�,q• X9892
��GFl�iQN�1l.
Stork Drainage Narrative
This project entails the remodeling/reconfiguration of an existing structure on Butler
Avenue on Tybee Island and addition of three pervious parking spaces and sidewalk.
The removal of existing impervious surfaces is approximately equal to the addition of
new impervious surfaces, with the pre -project impervious area of 2,222 sf and post -
project area of 2,210 sf. Due to this balance, the run-off volume generated by
construction of the proposed improvements is unchanged from the current condition.
The existing drainage pattern directs storm water overland from the Butler Street frontage
westerly towards the southwest corner of the lot. The drainage pattern post construction
will direct water easterly towards Butler Avenue, but it will be intercepted by small
detention facilities before reaching the public right of way.
The soils on the site are comprised of Chipley Urban land complex soils, as characterized
by the NRCS website. The soils are good for hydraulic conductivity, and assumed that
they are in Hydrologic Group A for the purpose of generating calculations for storm
water quantities. These quantities have been indicated in the attached calculations, and
25 year storm values have been included in the site development drawings.
I certify that these calculations and associated plans meet the requirements of the City of
Tybee Storm Water Management Ordinance.
0' 20' 40'
Graphic Scale 1"' = 20'
EQUIPMENT USED: TOTAL STA71ON
ANGULAR ERROR = 2" PER
ADJU57ED BY OBSERVA770M
PLAT CLOSURE = 1/30,000+
FIELD CLOSURE = 1/71,783
CONCRETE
THIS AREA RESERVED FOR
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REFERENCES
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1. PLAT BOOK 7-P, PAGE 478.
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2. A TOPOGRAPHIC SURVEY OF LOT 5A,
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SURVEYING, DATED 3/14/2014
3. DEED BOOK 300 V, PAGE 269.
4. PLAT BOOK 48-P, PAGE 80
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THIS SURVEY IS A RETRACEMENT OF AN EXISTING " EDGE OF
PARCEL OF LAND AND DOES NOT SUBDIVIDE OR 'o
CREATE A NFW PARCFL. THE RECORDING ASPHALT
.� N
INFORMATION OF THE DOCUMENT(S), MAP(S),
PLAT(S) OR OTHER INSTRUMENT(S) WHICH
CREATED THE PARCEL(S) ARE STATED HEREON.
RECORDATION OF THIS SURVEY DOES NOT IMPLY
APPROVAL OF THE LOCAL JURISDICTION,
AVAILABILITY OF PERMITS, COMPLIANCE WITH
LOCAL REGULATIONS OR REQUIREMENTS, NOR
SUITABILITY FOR ANY USE OR PURPOSE OF THE
LAND. FURTHER, THE UNDERSIGNED LAND
SURVEYOR CERTIFIES THAT THIS MAP, PLAT, OR
PLAN COMPLIES WITH THE MINIMUM TECHNICAL
STANDARDS FOR PROPERTY SURVEYS IN GEORGIA
AS SET FORTH IN CHAPTER 180-7 OF THE RULES
OF THE GEORGIA BOARD OF REGISTRATION FOR
PROFESSIONAL ENGINEERS AND LAND SURVEYORS
AND AS SET FORTH IN THE GEORGIA PLAT ACT
OCGA 15-6-67. /1 ._'*l ..a
BUTLER AVENUE 80'. RIGHT OF WAY
TAX ASSESSORS PROPERTY
IDENTIFICATION NUMBER: 4-0009-02-006
CURRENT ZONING. C-1
TOTAL LOT AREA: 0.125 ACRES
STREET ADDRESS.• 1705 BUTLER AVENUE
SURVEY NOTES:
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1. THE ELEVATIONS SHOWN ARE BASED ON
NAVD 88 DATUM.
2. COORDINATES AND DIRECTIONS ARE BASED
ON GEORGIA STATE PLANE COORDINATE
SYSTEM (NAD83), EAST ZONE.
3. ACCORDING TO F.I.R.M. MAP NO. 13051CO326F,
REVISED SEPTEMBER 26, 2008, THE
PROPERTY SHOWN ON THIS SURVEY LIES IN
ZONE AE(BFE 13).
4. ONLY ABOVEGROUND, READILY VISIBLE
STRUCTURES AND UTILITIES WERE LOCATED
FOR THIS SURVEY. THIS SURVEYOR MAKES
NO WARRANTY OR GUARANTEE AS TO THE
LOCATION, EXISTENCE, OR NON-EXISTENCE
OF ANY BELOWGROUND, NON-VISIBLE
UTILITIES OR STRUCTURES.
su m o A SURVEY Or
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B R E W E R
EASTERN PORTION OF LOT 7, WARD S
CITY OF TYBEE ISLAND. CHATHAM COUNTY. GEORGIA LAND SURVEYING
P.O. Box 441
N — -- - — ---' ---
__f _ Poolcr,GA31322
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Phone(912)856
PREPAREDFOR craig(u:brewersurvey.rnm
-2205 N FRANK KELLY www.BreecrrSurvcy.com
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Hydrograph Plot
Hydraflow Hydrographs by Intelisolve
Friday, Jan 19 2018, 10:22 AM
Hyd. No. 1
Tybee Beach Reso rt -P re -p roject
Hydrograph type
= SCS Runoff
Peak discharge
= 0.607 cfs
Storm frequency
= 25 yrs
Time interval
= 1 min
Drainage area
= 0.124 ac
Curve number
= 69
Basin Slope
= 0.0%
Hydraulic length
= Oft
Tc method
= TR55
Time of cone. (Tc)
= 3.30 min
Total precip.
= 8.00 in
Distribution
= Type III
Storm duration
= 24 hrs
Shape factor
= 300
Hydrograph Volume = 1,972 tuft
TybeeBeachResort-Pre-project
Q (cfs) Hyd. No. 1 -- 25 Yr Q (cfs)
1.00 - — 1.00
0.90 - -- — — 0.90
I ' -
0.80 — - - - 0.80
0.70 — - 0.70
i
0.60 - j j — 0.60
i
0.50 -i r— 0.50
0.40 -- - — 0.40
0.30 - -- — --- 0.30
0.20 - - ! -- — -i 0.20
0.10 -- — 0.10
000 000
0 2 5 7 9 12 14 16 19 21 23 26
Hyd No. 1 Time (hrs)
Y
Hydrograph Plot
Hydraflow Hydrographs by Intelisolve
Hyd. No. 2
Tybee Beach Resort -Post -p roject
Hydrograph type
= SCS Runoff
Storm frequency
= 25 yrs
Drainage area
= 0.124 ac
Basin Slope
= 0.0%
Tc method
= TR55
Total precip.
= 8.00 in
Storm duration
= 24 hrs
Friday, Oct 19 2018, 8:8 AM
Peak discharge = 0.607 cfs
Time interval
= 1 min
Curve number
= 69
Hydraulic length
= Oft
Time of cone. (Tc)
= 3.30 min
Distribution
= Type III
Shape factor
= 300
Hydrograph Volume = 1,972 cult
TybeelBeachResort-Post-project
Q (cfs) Hyd. No. 2 -- 25 Yr Q (cfs)
1.00 �— - - —� 1.00
0.90 - — 0.90
i
0.80 — ! - — - 0.80
0.70 0.70
j I
0.60 1—--�- —�- -; ;- - - - - 0.60
I I
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0.50- -
I
r -� � - i 0.50
I I
0.40 -1 - -�- — 0.40
i
0.30 r - -}— r -- - - { 0.30
I
I I
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0.20 h - - - -- - - �— i - -�— — I 0.20
0.10-- - - -- h - - -- 0.10
0.00 - -- — - i 0.00
0 2 5 7 9 12 14 16 19 21 23 26
Hyd No. 2 Time (hrs)
r
EL=8.1,0
'JUIN' OR 170F;MEl'-U
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'HAIRLES J. WILKINS JR P
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"IN: 4-0009-0,2-0030
MATCOH EUVA110N OF
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ING HEADER CURD
DOWNSPOUT I" -LONG R.
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SWALE PERCOtxnot4 SEECl 4 F -G= 10.40
DETAIL, M�G ,
Channel Report
Hydraflow Express by Intelisolve
Area A Swale
Q (cfs)
Triangular
Area (sgft)
Side Slope (z:1)
= 6.00
Total Depth (ft)
= 0.50
Invert Elev (ft)
= 100.00
Slope (%)
= 0.40
N -Value
= 0.035
Calculations
Compute by:
Known Q
Known Q (cfs)
= 0.15
Elev (ft)
101.00 —
100.75
Section
_ t
i
100.50 - - --
100.25 ---...- -- -
i
100.00 -+- - - -
99.75 -- -- -- —
0 1 2 3 4 5 6
Thursday, Nov 15 2018,12:5 PM
Highlighted
Depth (ft)
= 0.21
Q (cfs)
= 0.150
Area (sgft)
= 0.26
Velocity (ft/s)
= 0.57
Wetted Perim (ft)
= 2.55
Crit Depth, Yc (ft)
= 0.14
Top Width (ft)
= 2.52
EGL (ft)
= 0.21
Reach (ft)
i
7
Depth (ft)
1.00
0.75
0.50
-- 0.25
mennoffly1ril
I
1 -0.25
8
Channel Report
Hydraflow Express by Intelisolve
Area B Swale
Triangular
= 0.29
Side Slope (z:1)
= 6.00
Total Depth (ft)
= 0.50
Invert Elev (ft)
= 100.00
Slope (%)
= 0.25
N -Value
= 0.035
Calculations
Compute by: Known Q
Known Q (cfs) = 0.27
Thursday, Nov 15 2018, 12:8 PM
Highlighted
Depth (ft)
= 0.29
Q (cfs)
= 0.270
Area (sqft)
= 0.50
Velocity (ft/s)
= 0.54
Wetted Perim (ft)
= 3.53
Crit Depth, Yc (ft)
= 0.17
Top Width (ft)
= 3.48
EGL (ft)
= 0.29
Elev (ft) Section
101.00 -�---- -- �- —� —�-
100.75
!
I
I
100.50 - • i — -� ---r
rt
100.25
100.00 ---r - T----
99.75 --- - — - ^f
0 1 2 3 4 5
Reach (ft)
Depth (ft)
1.00
0.75
0.50
-- 0.25
0.00
6 7
-0.25
8
1
Table 2.1.5-1 Runoff Curve Numbers
Cover description
Cover type and Average percent
hydrologic condition impervious area
Cultivated land: without conservation treatment
with conservation treatment
Pasture or range land: poor condition
good condition
Meadow: good condition
Wood or forest land: thin stand, poor cover
good cover
3
Open,space (lawns, parks, golf courses, cemeteries, etc.)
Poor condition (grass cover <50%)
Fair condition (grass cover 50% to 75%)
Good condition (grass cover > 75%)
Impervious areas:
Paved parking lots, roofs, driveways, etc.
(excluding right-of-way)
Streets and roads:
Paved; curbs and storm drains (excluding
right-of-way)
Paved; open ditches (including right-of-way)
Gravel (including right-of-way)
Dirt (including right-of-way)
Urban districts:
Commercial and business 85%
Industrial 72%
Residential districts by average lot size:
1/8 acre or less (town houses) 65%
1/4 acre 38%
1/3 acre 30%
1/2 acre 25%
1 acre 20%
2 acres 12%
Developing urban areas and
Newly graded areas (pervious areas
only, no vegetation)
1 Average runoff condition, and'la = 0.2S
Curve numbers for
hydrologic soil groups
A
B
C
D
72
81
88
91
62
71
78
81
68
79
86
89
39
61
74
80
30
58
71
78
45
66
77
83
25
55
70
77
68 al. 86 89
49 69 79 84
39 61 74 80
98 98 98 98
98 98 98 98
83 89 92 93
76 85 89 91
72 / 82 87 89
89
92
94
95
81
88
91
93
77-
85
90
92
61
75
83
87
57
72
81
86
54
70
80
85
51
68
79
84
46
65
77
82
77
86
91
94
2 The average percent impervious area shown was used to develop the composite CNs. Other assumptions are as
follows: impervious areas are directly connected to the drainage system, impervious areas have a CN of 98, and pervious
areas are considered equivalent to open space in good hydrologic condition. If the impervious area is not connected, the
SCS method has an adjustment to reduce the effect.
3 CNs shown are equivalent to those of pasture. Composite CNs may be computed for other combinations of open space
cover type.
2.1.22 Georgia Stormwater Management Manual Volume 2 (Technical Handbook) i„
31° 59'27'N
Hydrologic Soil Group—Bryan and Chatham Counties, Georgia
0
514050 514070 514080
fi
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'T� '��,. r •cif. � .,:�• �`. .,r -
31° 59' 24" N
514060 514070 514060 514090 514100 514110 514120 514130 514140 514150 514160 514170 514180 514190 5142M 514210 514220 514210
3
k
Map Scale: 1:828 f printed on A landscape (11" x 8.5") deet
NMeters
n0 10 20 40 60
/V
0 40 80 160 240
Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UiM Zone 17N WGS84
31° 59'27" N
r
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i
31° 59' 24' N
3
F`
Natural Resources Web Soil Survey 1/19/2018
f i Conservation Service National Cooperative Soil Survey Page 1 of 4
Hydrologic Soil Group ---Bryan and Chatham Counties, Georgia
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
Cue Chipley-Urban land A 3.5
complex
Totals for Area of Interest 3.5
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long -duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink -swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff. None Specified
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
100.0%,
100.0%
1/19/2018
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1 Miles
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Feet
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