HomeMy WebLinkAbout20080989 Ver 1_Stormwater Info_20080709
Stonemont
Stormwater Calculations
B&F Consulting
2805 Tobermory Lane
Raleigh NC 27606
919 618 0180
UIR@f
qow7g f?)
JUL 9 2008
DENR - WATER QUAUTy
WLTIANDS AND STORMWATER BRANrH
•
•
Stonemont
Stormwater Calculations
B&F Consulting
2805 Tobermory Lane
Raleigh NC 27606
9196180180
• Wet Detention Basin Calculations, Worksheets
and
O&M Agreements
0
C7
0 Stonemont
Anti-flotation calculations
Outlet structures for ponds
Provide Concrete "waffle box"
Exterior dimensions 4'X 4'
length width
A 4
B 4
C 4
Bouyant force Concrete factor of
height (Ibs) (Ibs) saftey
4 1.3 1298 2803 2.2
4 1.9 1897 2803 1.5
4 1.3 1298 2803 2.2
Use concrete weight as 150 Ibs/c.f.
Thus, resistant force for concrete is (150-62.4) X 2 X 4 X 4 = 2800 Ibs.
•
0
0-
POND
A
C7
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
•
rI
•
BMP element: Potential problem: How I will rernediate the problem:
The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the
swale sediment off-site.
The pipe is cracked or Replace the pipe.
otherwise damaged.
Erosion is occurring in the Regrade the swale if necessary to
swale. smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design depth for possible. Remove the sediment and
sediment storage. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf Best professional practices Prune according to best professional
show that pruning is needed practices
to maintain optimal plant
health.
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 to establish the
ground cover if a soil test indicates
it is necessary.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it orl
the plants rather than spraying.
The main treatment area Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design sediment possible. Remove the sediment and
storage depth. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over Consult a professional to remove
50% of the area. and control the algal growth.
Cattails, phragmites or other Remove the plants by wiping them
invasive plants cover 50% of with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.3 Page 2 of 4
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
•
BMP element: Potential problem: How I will remediate the problem:
The embankment Shrubs have started to grow Remove shrubs immediately.
on the embankment.
Evidence of muskrat or Use traps to remove muskrats and
beaver activity is present. consult a professional to remove
beavers.
A tree has started to grow on Consult a dam safety specialist to
the embankment. remove the tree.
An annual inspection by an Make all needed repairs.
appropriate professional
shows that the embankment
needs repair.
The outlet device Clogging has occurred. Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is damaged Repair or replace the outlet device.
The receiving water Erosion or other signs of Contact the local NC Division of
damage have occurred at the Water Quality Regional Office, or
outlet. the 401 Oversight Unit at 919-733-
1786.
The measuring device used to determine the sediment elevation shall be such
• that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads 319.0 feet in the main pond, the
sediment shall be removed.
When the permanent pool depth reads 324.0 feet in the forebay, the sediment
shall be removed.
BASIN DIAGRAM
ill in the blanks)
n
0 Permanent Pool Elevation 326.0
Sediment Removal E. 324.0 ol
----------------- Sediment Removal Elevation 319.0 Volume
Bottom E evatio 322.0 ------------------------------- ----------- ---Bottom Elevation 316.0 1-ft n
Storage Sedimei
Storage
FOREBAY MAIN POND
Form SW401-Wet Detention Basin O&M-Rev.3
Page 3 of 4
•
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: Stonemont
BMP drainage area number: "A"
Print name: :::W1 ?.T6 Mdg:S <V-
Title:_ McDU
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, S • rt , 6 7isuC S, .T? , a Notary Public for the State of
A9
County of Gc ?? •2 , do hereby certify that
Cc w o??`S L rv n,e S J ""'p personally appeared before me this
day of ?.?.? 2" S! and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements. Witness my hand and official
seal, _5"'. = (-7
?`?? ZZr
U
G =
`may 'OU g?-` ,?-?'••'`
SEAL
•
My commission expires ? • L/ ?D
Form SW401-Wet Detention Basin O&M-Rev.3
Page 4 of 4
Address: 140 TOyyftsle'Lc,tt C.OUQT
Permit Number:
0-
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin 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.
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
? does ® does not incorporate a vegetated filter at the outlet.
This system (check one):
? does ® does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
- Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
- No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
- Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
- If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
•
- Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must 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 BMP Trash/debris is resent. Remove the trash/debris.
The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to
detention basin 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.
Vegetation is too short or too Maintain vegetation at a height of
long. a roximatel six inches.
Form SW401-Wet Detention Basin O&M-Rev.3
Page 1 of 4
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:
Stonemont
BMP drainage area number:
Print name: Curtis Jones, Jr.
Title: member
Address: 140 Towerview Court, Cary, NC
Phone: 919-669-1246
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, M 152k( 4• PC-?,kL GIl , a Notary Public for the State of
M4 rf?h of n I/ns, , County of 1 Akin , do hereby certify that
C,Jrfis Tones Yr, personally appeared before me this 92??
day of ZC06, and acknowledge the due execution of the
forgoing filter st ip, riparian buffer, and/or level spreader maintenance requirements.
Witness my hand and official seal,
SEAL
0 My commission expires old. 2 ! 700
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 of 3
DWQ Project
0 DIVISION OF WATER QUALITY - LEVEL SPREADER WORKSHEET (112007)
1. PROJECT INFORMATION (please complete the following information):
Project Name : S -DNNSVOAJZ'
Contact Person: I:SS ELL grIg4 rnF Phone Number: (fl l) 69;-D1A0
Level Spreader ID:
Level Spreader Length ft. (perpendicular to flow)
Drainage Area ac. (on-site and off-site drainage to the level spreader)
Impervious Area ac. (on-site and off-site drainage to the level spreader)
Forebay Area cu ft. (0.2% of the contributing impervious surface area)
Maximum Filter Strip/Buffer Slope % (6% for forested, leaf littler cover, 8% for thick ground cover
grass
Max. Discharge from 1"/Hr Storm cfs
Max. Discharge to Level Spreader cfs
Filter Strip/ Zone 2 Buffer Vegetation 4^ (thick ground cover or grass; canopied forest with leaf litter
groundcover)
Pre-treatment or Bypass Method Used
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Applicants Initials
VAA Project Site was visited prior to designing level spreader.
1921
Bypass conveyance method is specified and plan details and calculations are provided.
?,?_Alternative design option is specified and plan details and calculations are provided.
Date of the Site visit. PLEASE ATTACH TIME-DATED DIGITAL PHOTO OF EXISTING BUFFER CONDITIONS.
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 65 ft per cfs in canopied forest with leaf
litter for 50-foot buffer; 50 ft per cfs for 100-foot buffer, or 40 ft. per cfs for 150-foot buffer.
/G_Pre-Formed Scour Holes are on flat slopes only.
No structures are located in protected buffers (must meet no practical alternatives criteria).
Design Alternative (if any) and Bypass method used:
Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
No structures are located in protected buffers.
d1o Plan details for the bypass and outlets are provided.
QAhL_The operation and maintenance agreement includes annual erosion and vegetation repair.
The operation and maintenance agreement signed and notarized by the responsible party is provided.
Permit No.
(to be provided by DWQ)
7 a$oC W A tfigpG
A
,?1i11111111111111?R 0 y
hICDENR `
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Stonemont
Contact person Russell Briggs, P.E.
Phone number 919-618-0180
Date 7-Jul-08
Drainage area number "A"
II. DESIGN INFORMATION
Site Characteristics
Drainage area 244,371.60 ft2
Impervious area 96,703.20 ft2
% impervious 39.57 %
Design rainfall depth 1.00 in
Storage Volume: Non-SR Waters
Minimum volume required 8,349.00 ft3
Volume provided 9,800.00 ft3
Storage Volume: SR Waters
1-yr, 24-hr runoff depth in
Pre-development 1-yr, 24-hr runoff ft3
. Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Peak Flow Calculations
1-yr, 24-hr rainfall depth 2.89 in
Rational C, pre-development 0.25 (unitless)
Rational C, post-development 0.55 (unitless)
Rainfall intensity: 1-yr, 24-hr storm 4.90 in/hr
Pre-development 1-yr, 24-hr peak flow 6.87 ft3/sec
Post-development 1-yr, 24-hr peak flow 15.12 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control 8.25 ft3/sec
Basin Elevations
Basin bottom elevation 316.30 ft
Sediment cleanout elevation 320.00 ft
Bottom of shelf elevation 325.50 ft
Permanent pool elevation 326.00 ft
SHWT elevation 320.00 ft
Top of shelf elevation 326.50 ft
Temporary pool elevation 325.40 ft
•
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2
Permit No.
(to be provided by DWQ)
II. DESIGN INFORMATION
Volume and Surface Area Calculations
SA/DA ratio 1.73 (unitless)
Surface area at the bottom of shelf 4,531.00 ftz
Volume at the bottom of shelf 15,454.00 ft3
Permanent pool, surface area required 4,227.00 ftz
Permanent pool, surface area provided 6,038.00 ftz OK
Permanent pool volume 18,128.00 ft3
Average depth for SA/DA tables 3.00 ft OK
Surface area at the top of shelf 7,637.00 ft2
Volume at the top of shelf 21,547.00 ft3
Forebay volume 3,986.00 ft3
Forebay % of permanent pool volume 21.99 % OK
Temporary pool, surface area provided 8,249.00 ftz
Drawdown Calculations
Treatment volume drawdown time 4.00 days OK
Treatment volume discharge rate 0.50 ft3/s
Pre-development 1-yr, 24-hr discharge 6.87 ft3/s OK
Post-development 1-yr, 24-hr discharge 6.78 ft3/s OK
Additional Information
Diameter of orifice 1 in
Design TSS removal 85 %
Basin side slopes 3.00 :1 OK
Vegetated shelf slope 10.00 :1 OK
Vegetated shelf width 10.00 ft OK
Length of flowpath to width ratio 3.00 :1 OK
Length to width ratio 1.50 :1 OK
Trash rack for overflow & orifice? Y (Y or N) OK
Freeboard provided 1.00 ft OK
Vegetated filter provided? y (Y or N) OK
Recorded drainage easement provided? y (Y or N) OK
Capures all runoff at ultimate build-out? y (Y or N) OK
Drain mechanism for maintenance or emergencies drain via pump
•
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2
Permit No
(to be provided by DWQ)
III. REQUIRED ITEMS CHECKLIST
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.
Pagel Plan
Initials Sheet No.
J0 J21
4n 12 1. Plans (1" 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),
Basin dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW),
Overflow device, and
Boundaries of drainage easement.
P213 C 1?3 3 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
- Outlet structuretwith trash rack or similar,
- Maintenance access,
- Permanent pool dimensions,
- Forebay and main pond with hardened emergency spillway,
- Basin cross-section,
- Vegetation specification for planting shelf, and
- Filter strip.
C17 3 3. Section view of the dry detention basin (1" = 20' or larger) showing:
Side slopes, 3:1 or lower,
Pretreatment and treatment areas, and
Inlet and outlet structures.
!1/?7 CV-3 38 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
?( on the plans prior to use as a wet detention basin.
?C?(Uk)5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
to verify volume provided.
6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
>? /} 9. A copy of the deed restrictions (if required).
10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
•
Form SW401-Wet Detention Basin-Rev.4 Part III. Required Items Checklist, Page 1 of 1
0 Basin "A"
Area of Right of way 1.83 acres
Impervious area in street right of way 1.24 acres
Number of lots 11.5
Typical impervious area per lot (%)
Drive, sidewalk 600 sf
Footprint 3000 sf
Deck 120 sf
3720
Impervious area of lots: 0.98 acres
Total drainage area 5.61 acres
Total impervious area, lots + r/w 2.22
% impervious 40%
Use 40 % criteria 40%
SA/DA ratio for S depth 1.73%
SA 0.10 acres
Treatment volume
V =3630xRox(0.05+0.9xIQ)xA
where
V = Volume of runoff to be controlled (ft3)
Ro = Design storm rainfall depth (1")
A = watershed area (ac.)
V = 8349 cf
•
Pond A
Average Pond Depth = 3.0 NOTE: Excludes sediment storage
Elevation SF Area CF Volume Shelf from e.325.5 to e.326.5
329.5 11177 49405
328 9419 33958
327.5 8317 29524
326.5 7637 21547 <-shelf
326 6038 18128 <-n.pool
325.5 4531 15486 <-shelf
324 3408 9532
322 2100 4024
320 1057 867
319 676 0 <-sediment storage elevation (start avg. depth calc here)
318 305 0
316 0 0 Sed. Storage depth = 3.0 ft
Forebay Volume
Elevation SF Area CF Volume
332 1610 3986
330 950 1426
•
328 476 0
326 140 0
324 0 0
Water Quality Volume: 8349 CF (above normal pool)
This volume occurs 1.12 feet above normal pool
Set weir at 1.3' above normal pool
Volume provided = 9800
0
. Basin A
Pond Routing
1-yr, 24 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TIC [min]
Intensities, I
1-year [in/hr]
• Peak Discharge, Qp
1-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 6 hour storm
1-year [inches]
Volume of Runoff, V, from 6-hour storm
1-year [inches]
1-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
1-year [minutes]
Time Interval for Routing
• 1-year [minutes]
3.39
2.22
5.61
0.55
5.0
4.90
15.12
B
98.0
61.0
75.6
3.2
2.89
v = ((P-.2S)"2)/(P+.8s)
0.92
0.43
Tp = V/(1.39*Qp)
14.9
1
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
• BASIN PARAMETERS
Riser Barrel Emergency Spillway
12 = Weir length 24 = Dia. barrel (inches) 40 =Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
327.3 = Crest elev. Weir 326 = .Invert elev. barrel 329.5 =Crest elev.
326.0 = Initial elev. water level
Results
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
1 6.78 327.61 15.12
• ROUTING AND ANALYSIS - 1-year storm
Time Inflow Storage Stage
[mins] [cfs] [cubic ft] [ft]
0.0 0.0 0 326.00
1.0 0.2 0 326.00
2.0 0.7 10 326.00
3.0 1.5 50 326.01
4.0 2.5 137 326.02
5.0 3.8 289 326.04
6.0 5.3 519 326.08
7.0 6.8 836 326.12
8.0 8.4 1,246 326.18
9.0 10.0 1,752 326.26
10.0 11.4 2,351 326.34
11.0 12.7 3,037 326.44
12.0 13.7 3,799 326.55
13.0 14.5 4,623 326.65
14.0 15.0 5,494 326.76
15.0 15.1 6,393 326.87
16.0 14.9 7,300 326.99
17.0 14.4 8,196 327.10
18.0 13.6 9,059 327.21
• 19.0 12.5 9,873 327.31
20.0 11.5 10,622 327.40
21.0 10.5 11,231 327.48
22.0 9.6 11,681 327.53
23.0 8.8 11,993 327.57
24.0 8.1 12,194 327.59
25.0 7.4 12,308 327.60
26.0 6.8 12,357 327.61
27.0 6.2 12,358 327.61
28.0 5.7 12,324 327.60
29.0 5.2 12,267 327.60
30.0 4.8 12,194 327.59
31.0 4.4 12,110 327.58
32.0 4.0 12,021 327.57
33.0 3.7 11,928 327.56
34.0 3.4 11,834 327.55
35.0 3.1 11,741 327.54
36.0 2.8 11,650 327.53
37.0 2.6 11,560 327.52
38.0 2.4 11,474 327.51
327.6
Outflow
[cfs]
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.3
3.0
4.4
5.5
6.2
6.6
6.8
6.8
6.7
6.4
6.2
5.9
5.6
5.3
4.9
4.6
4.3
4.0
3.8
Outlet Hydraulics
Q_orifice Q Q_riser
em.spil
0.0
0.0
0.0
0.1
0.2
0.3
0.6
0.9
1.4
1.9
2.6
3.4
4.1
4.9
5.7
6.6
7.5
8.3
9.1
9.9
10.6
11.2
11.6
11.8
12.0
12.1
12.1
12.1
12.1
12.1
12.0
11.9
11.9
11.8
11.7
11.6
11.5
11.5
11.4
6.8 < == maximum 1-yr
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 1.3
0 3.0
0 4.4
0 5.5
0 6.2
0 6.6
0 6.8
0 6.8
0 6.7
0 6.4
0 6.2
0 5.9
0 5.6
0 5.3
0 4.9
0 4.6
0 4.3
0 4.0
0 3.8
0
• Basin A
Pond Routing
100-yr, 6 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TC [min]
Intensities, I
100-year [in/hr]
• Peak Discharge, Qp
100-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 6 hour storm
100-year [inches]
Volume of Runoff, V, from 6-hour storm
100-year [inches]
100-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
100-year [minutes]
Time Interval for Routing
• 100-year [minutes]
3.39
2.22
5.61
0.55
5.0
9.12
28.14
B
98.0
61.0
75.6
3.2
5.39
v = ((p-.2S)"2)/(p+.8s)
2.83
1.32
Tp = V/(1.39*Qp)
24.5
2
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
• BASIN PARAMETERS
•
Riser Barrel Emergency Spillway
12 = Weir length 24 = Dia. barrel (inches) 40 =Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
327.3 =Crest elev. Weir 326 = Invert elev. barrel 329.5 = Crest elev.
326.0 = Initial elev. water level
Results, 100-year 6 hour
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
100 14.70 327.95 28.14
0
ROUTING AND ANALYSIS --100-year 6 hour storm
Outlet Hydraulics
Time Inflow Storage Stage Outflow Q_orifice Q
[mins] [cfs] [cubic ft] [ft] [cfs] em.spi l
0.0 0.0 0 326.00 0.0 0.0 0
2.0 0.5 0 326.00 0.0 0.0 0
4.0 1.8 1 326.00 0.0 0.0 0
6.0 4.0 218 326.03 0.0 0.2 0
8.0 6.8 2 326.00 0.0 0.0 0
10.0 10.0 408 326.06 0.0 0.5 0
12.0 13.6 1,010 326.15 0.0 1.1 0
14.0 17.2 1,825 326.27 0.0 2.0 0
16.0 20.5 2,855 326.42 0.0 3.2 0
18.0 23.5 4,088 326.58 0.0 4.4 0
20.0 25.8 5,497 326.76 0.0 5.7 0
22.0 27.4 7,048 326.95 0.0 7.2 0
24.0 28.1 8,692 327.16 0.0 8.8 0
26.0 27.9 10,378 327.37 0.8 10.4 0
28.0 26.8 12,005 327.57 5.5 11.8 0
30.0 24.8 13,281 327.71 10.5 12.9 0
32.0 22.4 14,141 327.81 13.7 13.7 0
34.0 20.2 14,666 327.87 14.1 14.1 0
36.0 18.1 15,029 327.91 14.4 14.4 0
38.0 16.3 15,251 327.93 14.6 14.6 0
40.0 14.7 15,353 327.95 14.7 14.7 0
42.0 13.2 15,351 327.95 14.7 14.7 0
44.0 11.9 15,261 327.94 14.6 14.6 0
46.0 10.7 15,096 327.92 14.5 14.5 0
48.0 9.6 14,868 327.89 14.3 14.3 0
50.0 8.6 14,587 327.86 14.0 14.0 0
52.0 7.8 14,262 327.82 13.8 13.8 0
54.0 7.0 13,902 327.78 13.3 13.5 0
56.0 6.3 13,524 327.74 11.6 13.1 0
58.0 5.7 13,208 327.70 10.2 12.9 0
60.0 5.1 12,936 327.67 9.0 12.6 0
62.0 4.6 12,698 327.65 8.1 12.4 0
64.0 4.1 12,487 327.62 7.3 12.3 0
66.0 3.7 12,298 327.60 6.6 12.1 0
68.0 3.3 12,126 327.58 5.9 11.9 0
70.0 3.0 11,969 327.56 5.4 11.8 0
72.0 2.7 11,825 327.55 4.9 11.7 0
74.0 2.4 11,692 327.53 4.5 11.6 0
76.0 2.2 11,570 327.52 4.1 11.5 0
327.9 14.7 < ==maximum 100-yr 6 hour
Q_riser
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.8
5.5
10.5
14.4
17.0
18.9
20.0
20.6
20.6
20.1
19.2
18.0
16.6
15.0
13.3
11.6
10.2
9.0
8.1
7.3
6.6
5.9
5.4
4.9
4.5
4.1
0
Basin A
Pond Routing
100-yr, 24 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TIC [min]
Intensities, I
100-year [in/hr]
Peak Discharge, Qp
100-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 24 hour storm
100-year [inches]
Volume of Runoff, V, from 24-hour storm
100-year [inches]
100-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
100-year [minutes]
Time Interval for Routing
100-year [minutes]
B
3.39
2.22
5.61
0.55
5.0
9.12
28.14
98.0
61.0
75.6
3.2
7.59
v = ((P-.2S)"2)/(P+.8s)
4.75
2.22
Tp = V/(1.39"Qp)
41.2
2
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
• BASIN PARAMETERS
•
Riser Barrel Emergency Spillway
12 = Weir length 24 = Dia. barrel (inches) 40 =Length
3.3 = Cw weir 0.6 =•Cd barrel 3.00 = Cw
327.3 = Crest elev. Weir 326 = Invert elev. barrel 329.5 = Crest elev.
326.0 = Initial elev. water level
Results, 100-yr 24 hour
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
100 17.67 328.37 28.14
0
ROUTING AND ANALYSIS --100-year 24 hour storm
Outlet Hydraulics
Time Inflow Storage Stage Outflow Q_orifice Q
[mins] [cfs] [cubic ft] [ft] [cfs] em.spi l
0.0 0.0 0 326.00 0.0 0.0 0
2.0 0.2 0 326.00 0.0 0.0 0
4.0 0.7 1 326.00 0.0 0.0 0
6.0 1.4 79 326.01 0.0 0.1 0
8.0 2.5 2 326.00 0.0 0.0 0
10.0 3.9 154 326.02 0.0 0.2 0
12.0 5.5 388 326.06 0.0 0.4 0
14.0 7.3 718 326.11 0.0 0.8 0
16.0 9.2 1,156 326.17 0.0 1.3 0
18.0 11.3 1,710 326.25 0.0 1.9 0
20.0 13.4 2,389 326.35 0.0 2.6 0
22.0 15.6 3,195 326.47 0.0 3.5 0
24.0 17.7 4,130 326.59 0.0 4.4 0
26.0 19.7 5,191 326.72 0.0 5.5 0
28.0 21.6 6,374 326.87 0.0 6.6 0
30.0 23.3 7,670 327.03 0.0 7.8 0
32.0 24.8 9,070 327.21 0.0 9.1 0
34.0 26.1 10,559 327.40 1.2 10.5 0
36.0 27.1 12,054 327.57 5.7 11.9 0
38.0 27.7 13,336 327.72 10.7 13.0 0
• 40.0 28.1 14,356 327.83 13.8 13.8 0
42.0 28.1 15,210 327.93 14.6 14.6 0
44.0 27.8 16,022 328.02 15.2 15.2 0
46.0 27.2 16,777 328.09 15.8 15.8 0
48.0 26.3 17,462 328.16 16.3 16.3 0
50.0 25.1 18,063 328.22 16.7 16.7 0
52.0 23.7 18,568 328.27 17.0 17.0 0
54.0 22.2 18,968 328.30 17.3 17.3 0
56.0 20.8 19,265 328.33 17.4 17.4 0
58.0 19.6 19,469 328.35 17.6 17.6 0
60.0 18.4 19,589 328.37 17.6 17.6 0
62.0 17.2 19,633 328.37 17.7 17.7 0
64.0 16.2 19,608 328.37 17.7 17.7 0
66.0 15.2 19,520 328.36 17.6 17.6 0
68.0 14.3 19,376 328.34 17.5 17.5 0
70.0 13.4 19,182 328.33 17.4 17.4 0
72.0 12.6 18,943 328.30 17.2 17.2 0
74.0 11.8 18,663 328.28 17.1 17.1 0
76.0 11.1 18,349 328.24 16.8 16.8 0
328.4 17.7 < ==maximum 100-yr 24 hour
Q_riser
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.2
5.7
10.7
15.4
19.8
24.1
27.9
31.5
34.8
37.6
39.9
41.6
42.8
43.5
43.8
43.6
43.1
42.3
41.1
39.7
38.1
36.4
L_J
• Analysis of time to empty
Time Inflow Storage Stage 'Outflow
[hrs] [cfs] [cubic ft] IN [cfs]
0.0 0.0 9,800 327.30
6.0 0.0 9,066 327.21
12.0 0.0 8,357 327.12
18.0 0.0 7,672 327.03
24.0 0.0 7,010 326.95
30.0 0.0 6,373 326.87
36.0 0.0 5,760 326.79
42.0 0.0 5,171 326.72
48.0 0.0 4,606 326.65
54.0 0.0 4,066 326.58
60.0 0.0 3,549 326.52
66.0 0.0 3,057 326.45
72.0 0.0 2,592 326.38
78.0 0.0 2,156 326.32
84.0 0.0 1,748 326.26
90.0 0.0 1,369 326.20
96.0 0.0 1,019 326.15
102.0 0.0 697 326.10
108.0 0.0 404 326.06
114.0 0.0 140 326.02
120.0 0.0 (94)
63.0
Outlet Hydraulics
Q_barrel Q Q_riser
em.spil
0.034 9.8 0 0.0
0.033 9.1 0 0.0
0.032 8.5 0 0.0
0.031 7.8 0 0.0
0.030 7.2 0 0.0
0.028 6.6 0 0.0
0.027 6.0 0 0.0
0.026 5.4 0 0.0
0.025 4.9 0 0.0
0.024 4.4 0 0.0
0.023 3.9 0 0.0
0.022 3.4 0 0.0
0.020 2.9 0 0.0
0.019 2.4 0 0.0
0.018 1.9 0 0.0
0.016 1.5 0 0.0
0.015 1.1 0 0.0
0.014 0.8 0 0.0
0.012 0.4 0 0.0
0.011 0.2 0 0.0
0
• Soil Investigation
Pond "A"
A hand auger was used to advance a test hole approximately 30 inches in depth in two
locations of the proposed pond. The soil found appears to be a clay loam. The soil
samples were well drained.
We recommend a geotechnical engineer, or B&F Consulting be present during
construction of this pond in particular to ascertain whether a lining material (clay) will be
required as the pond is excavated to its proposed depths. The presence of the nearby
stream does indicate groundwater availability at a depth of the invert of the stream.
0
•
E
POND B
•
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
is
•
Wet Detention Basin Operation and Maintenance Agreement
of structures, safety of the public, and the removal efficiency of the BMP.
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
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
? does ® does not incorporate a vegetated filter at the outlet.
This system (check one):
? does ® does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
- Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
- No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
- Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
- If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
•
- Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must be available upon request.
Inspection activities shall be petformed as follows. Any problems that are found shall
be repaired immediately.
BMP element: Potential problem: How I will remediate the problem:
The entire BMP Trash/debris is resent. Remove the trash/debris.
The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to
detention basin 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.
Vegetation is too short or too Maintain vegetation at a height of
long. approximately six inches.
Form SW401-Wet Detention Basin O&M-Rev.3
Page 1 of 4
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
•
C]
E
BMP element: Potential problem: How I will remediate the problem:
The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the
swale sediment off-site.
The pipe is cracked or Replace the pipe.
otherwise damaged.
Erosion is occurring in the Regrade the swale if necessary to
swale. smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design depth for possible. Remove the sediment and
sediment storage. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf Best professional practices Prune according to best professional
show that pruning is needed practices
to maintain optimal plant
health.
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 to establish the
ground cover if a soil test indicates
it is necessary.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design sediment possible. Remove the sediment and
storage depth. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over Consult a professional to remove
50% of the area. and control the algal growth.
Cattails, phragmites or other Remove the plants by wiping them
invasive plants cover 50% of with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.3 Page 2 of 4
Permit Number:
•
(to be provided by DWQ)
Drainage Area Number:
BMP element: Potential problem: How I will remediate the problem:
The embankment Shrubs have started to grow Remove shrubs immediately.
on the embankment.
Evidence of muskrat or Use traps to remove muskrats and
beaver activity is present. consult a professional to remove
beavers.
A tree has started to grow on Consult a dam safety specialist to
the embankment. remove the tree.
An annual inspection by an Make all needed repairs.
appropriate professional
shows that the embankment
needs repair.
The outlet device Clogging has occurred. Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is damaged Repair or replace the outlet device.
The receiving water Erosion or other signs of Contact the local NC Division of
damage have occurred at the Water Quality Regional Office, or
outlet. the 401 Oversight Unit at 919-733-
1786.
The measuring device used to determine the sediment elevation shall be such
. that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads 323.0 feet in the main pond, the
sediment shall be removed.
•
When the permanent pool depth reads 326.0 feet in the forebay, the sediment
shall be removed.
BASIN DIAGRAM
ill in the blanks)
0 Permanent Pool Elevation 330.0
Sediment Removal E. 326.0 Pe anen Pool
- - - - - - - - - - - - - - - - - Volume Sediment Removal Elevation 323.0 Volume
-
Bottom E evatio 324.0 -ft Min.
-------------------------------------------- -----Sediment Bottom Elevation 320.0 1-ft r
Storage Sedimei
Storage
FOREBAY MAIN POND
Form SW401-Wet Detention Basin O&M-Rev.3
Page 3 of 4
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: Stonemont
BMP drainage area number: "B"
Print name: 1-11U23:5 I_f,S' JV_
Title:
T
Address: . GAJ2 -e d C_
Phone
Signat
Date: 3/o S
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, S, xl L 444?s .Q , a Notary Public for the State of
VLl L , County of l)u le e , do hereby certify that
& Js personally appeared before me this 13
day of T,,LL?e_ 200k, and acknowledge the due execution of the
forgoing wet detention basin aintenance requirements. Witness my hand and official
seal, r ??
OTAR}
S
03
?C)
SEAL
My commission expires i • I-/ Zm[/
•
Form SW401-Wet Detention Basin O&M-Rev.3 Page 4 of 4 '
Permit No.
(to be provided by DWQ)
oC W nT?q
EWA
AYNIbIIk .A111111111111I111111F ?' y
WaENR `
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
11. PROJECT INFORMATION
Project name Stonemont
Contact person Russell Briggs, P.E.
Phone number 919-618-0180
Date 7-Jul-08
Drainage area number "B"
II. DESIGN INFORMATION
Site Characteristics
Drainage area 300,564.00 ft
Impervious area 143,748.00 f'
% impervious 47.83 %
Design rainfall depth 1.00 in
Storage Volume: Non-SR Waters
Minimum volume required 12,044.00 ft3
Volume provided 15,068.00 ft3
Storage Volume: SR Waters
1-yr, 24-hr runoff depth in
Pre-development 1-yr, 24-hr runoff
• Post-development 1-yr, 24-hr runoff ft3
ft3
Minimum volume required ft3
Volume provided ft3
Peak Flow Calculations
1-yr, 24-hr rainfall depth 2.89 in
Rational C, pre-development 0.25 (unitless)
Rational C, post-development 0.62 (unitless)
Rainfall intensity: 1-yr, 24-hr storm 4.90 in/hr
Pre-development 1-yr, 24-hr peak flow 8.45 ft3/sec
Post-development 1-yr, 24-hr peak flow 20.96 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control 12.51 ft3/sec
Basin Elevations
Basin bottom elevation 320.00 ft
Sediment cleanout elevation 323.00 ft
Bottom of shelf elevation 329.50 ft
Permanent pool elevation 330.00 ft
SHWT elevation 323.00 ft
Top of shelf elevation 330.50 ft
Temporary pool elevation 331.55 ft
•
401 CERTIFICATION APPLICATION FORM
STORMWATER This form must be filled MANAGEMENT out, printed PERMIT and submitted. APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2
Permit No.
(to be provided by DWQ)
ll. DESIGN INFORMATION
Volume and Surface Area Calculations
SA/DA ratio 2.03 (unitless)
• Surface area at the bottom of shelf 4,531.00 ftz
Volume at the bottom of shelf 15,454.00 ft3
Permanent pool, surface area required 4,227.00 ftz
Permanent pool, surface area provided 6,007.00 ftz OK
Permanent pool volume 18,094.00 ft3
Average depth for SA/DA tables 3.01 ft OK
Surface area at the top of shelf 7,592.00 ftz
Volume at the top of shelf 21,494.00 ft3
Forebay volume 3,800.00 ft3
Forebay % of permanent pool volume 21.00 % OK
Temporary pool, surface area provided 8,249.00 ftz
Drawdown Calculations
Treatment volume drawdown time 4.00 days OK
Treatment volume discharge rate 0.04 ft3/s
Pre-development 1-yr, 24-hr discharge 8.45 ft3/s OK
Post-development 1-yr, 24-hr discharge 8.03 ft3/s OK
Additional Information
Diameter of orifice 1 in
Design TSS removal 85 %
Basin side slopes 3.00 :1 OK
Vegetated shelf slope 10.00 :1 OK
Vegetated shelf width 10.00 ft OK
Length of flowpath to width ratio 3.00 :1 OK
Length to width ratio 1.50 :1 OK
Trash rack for overflow & orifice? Y (Y or N) OK
Freeboard provided 1.00 ft OK
. Vegetated filter provided? Y (Y or N) OK
Recorded drainage easement provided? y (Y or N) OK
Capures all runoff at ultimate build-out? y (Y or N) OK
Drain mechanism for maintenance or emergencies drain via pump
•
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2
Permit N
(to be provided by DWQ)
• III. REQUIRED ITEMS CHECKLIST
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.
Pagel Plan
Initials Sheet No.
pip ?F 1. Plans (1" 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),
- Basin dimensions,
- Pretreatment system,
- High flow bypass system,
- Maintenance access,
- Proposed drainage easement and public right of way (ROW),
- Overflow device, and
- Boundaries of drainage easement.
•
detention basin.
M G
A CS 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
to verify volume provided.
3 ?1 r" 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
_?_ ?F 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
1 _ -
-Maintenance access,
- Permanent pool dimensions,
Forebay and main pond with hardened emergency spillway,
- Basin cross-section,
-Vegetation specification for planting shelf, and
Outlet on the plans structure prior to with use as trash a rack wet or similar,
- Filter strip.
G17 3 (?
3. Section view of the dry detention basin (1" = 20'or larger) showing:
-Side slopes, 3:1 or lower,
- Pretreatment and treatment areas, and
-Inlet and outlet structures.
C 3.3;F 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
7. The supporting calculations.
n
U
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
_ F 9. A copy of the deed restrictions (if required).
bt lf*-t 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
Form SW401-Wet Detention Basin-Rev.4
Part III. Required Items Checklist, Page 1 of 1
0 Basin "B"
Area of Right of way 3.5 acres
Impervious area in street right of way 2.12 acres
Number of lots 8
Typical impervious area per lot (%)
Drive, sidewalk 600 sf
Footprint 3000 sf
Deck 120 sf
3720
Impervious area of lots: 0.68 acres
Area of Rec Center 1.004 acres
Impervious area of Rec Cen ter 0.4 acres
Total drainage area 6.90 acres
Total impervious area, lots + r/w + rec center 3.20
% impervious 46%
Use 50 % criteria 50%
SA/DA ratio for 3' depth 2.06%
SA 0.14 acres
6191.62
•
Treatment volume
V =3630xROx(O.05+0.9x1a)xA
where
V = Volume of runoff to be controlled (ft3)
Ro = Design storm rainfall depth (P)
A = watershed area (ac.)
V = 11717 cf
0
•
C
Pond B
Average Pond Depth = 3.01 (excludes sediment storage)
Elevation SF Area CF Volume Shelf from e.329.5 to e.330.5
334 11239 54420
332 9153 34052
331.5 8618 29599
330.5 7592 21494
330 6007 18094 <-n.pool 20% of NP volume = 3619 cf
329.5 4536 15458 <-shelf
328 3412 9497
326 2095 3990
324 1053 842
323 631 0 <-sediment storage elevation (start avg. depth calc here)
322 309 0
320 0 0 Sed. Storage depth = 3.0 ft
Forebay Volume
Elevation SF Area CF Volume
332 1630 4565
330 967 1968
328 476 525
326 49 0
Water Quality Volume: 12044 CF (above normal pool)
This volume occurs 1.55 feet above normal pool
Set weir at 1.9' above normal pool
Volume provided = 15068
0
Pond Routing
1-yr, 24 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TC [min]
Intensities, I
1-year [in/hr]
• Peak Discharge, Qp
1-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 6 hour storm
1-year [inches]
Volume of Runoff, V, from 6-hour storm
1-year [inches]
1-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
1-year [minutes]
Time Interval for Routing
1-year [minutes]
• Basin B
B
3.70
3.20
6.90
0.60
5.0
4.90
20.29
98.0
61.0
78.2
2.8
2.89
v = ((p-.2S)"2)/(p+.8s)
1.06
0.61
Tp = V/(1.39"Qp)
15.7
1
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
0.30
0.98
0 BASIN PARAMETERS
L J
Riser Barrel Emergency Spillway
12 = Weir length 24 = Dia. barrel (inches) 40 = Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
331.90 = Crest elev. Weir 330 ='Invert elev. barrel 334.0 = Crest elev.
330.0 = Initial elev. water level
Results
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
1 8.03 332.25 20.29
0
• ROUTING AND ANALYSIS - 1-year storm
Time Inflow Storage Stage
[mins] [cfs] [cubic ft] IN
0.0 0.0 0 330.00
1.0 0.2 0 330.00
2.0 0.8 12 330.00
3.0 1.8 60 330.01
4.0 3.1 167 330.02
5.0 4.7 352 330.05
6.0 6.5 632 330.09
7.0 8.4 1,020 330.15
8.0 10.5 1,526 330.22
9.0 12.5 2,153 330.32
10.0 14.4 2,901 330.43
11.0 16.1 3,763 330.54
12.0 17.6 4,731 330.66
13.0 18.8 5,789 330.79
14.0 19.7 6,920 330.93
15.0 20.2 8,102 331.08
16.0 20.3 9,314 331.23
17.0 19.9 10,530 331.38
18.0 19.2 11,726 331.52
• 19.0 18.1 12,880 331.65
20.0 16.8 13,969 331.78
21.0 15.5 14,977 331.89
22.0 14.2 15,904 332.00
23.0 13.1 16,689 332.07
24.0 12.1 17,304 332.13
25.0 11.1 17,761 332.18
26.0 10.2 18,079 332.21
27.0 9.4 18,284 332.23
28.0 8.7 18,400 332.24
29.0 8.0 18,447 332.25
30.0 7.3 18,444 332.24
31.0 6.8 18,403 332.24
32.0 6.2 18,335 332.23
33.0 5.7 18,249 332.23
34.0 5.3 18,151 332.22
35.0 4.9 18,045 332.21
36.0 4.5 17,934 332.19
37.0 4.1 17,822 332.18
38.0 3.8 17,709 332.17
332.2
Outflow
[cfs]
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.2
2.8
4.5
5.8
6.8
7.5
7.9
8.0
8.0
7.9
7.7
7.4
7.0
6.7
6.3
6.0
5.6
Outlet Hydraulics
Q_orifice Q
em.spil
0.0 0
0.0 0
0.0 0
0.1 0
0.2 0
0.4 0
0.7 0
1.1 0
1.7 0
2.4 0
3.2 0
4.1 0
5.0 0
6.0 0
7.1 0
8.2 0
9.3 0
10.4 0
11.5 0
12.5 0
13.4 0
14.3 0
15.1 0
15.6 0
16.1 0
16.4 0
16.6 0
16.7 0
16.8 0
16.9 0
16.9 0
16.8 0
16.8 0
16.7 0
16.7 0
16.6 0
16.5 0
16.4 0
16.4 0
8.0 < _= maximum 2-yr
Q_riser
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.2
2.8
4.5
5.8
6.8
7.5
7.9
8.0
8.0
7.9
7.7
7.4
7.0
6.7
6.3
6.0
5.6
0
• Analysis of time to empty
Time Inflow Storage Stage Outflow
[hrs] [cfs] [cubic ft] [ft] [cfs]
•
0.0 0.0 12,044 331.56 0.037
6.0 0.0 11,246 331.47 0.036
12.0 0.0 10,471 331.37 0.035
18.0 0.0 9,719 331.28 0.034
24.0 0.0 8,990 331.19 0.033
30.0 0.0 8,286 331.10 0.032
36.0 0.0 7,605 331.02 0.030
42.0 0.0 6,947 330.94 0.029
48.0 0.0 6,314 330.86 0.028
54.0 0.0 5,704 330.78 0.027
60.0 0.0 5,118 330.71 0.026
66.0 0.0 4,556 330.64 0.025
72.0 0.0 4,018 330.58 0.024
78.0 0.0 3,503 330.51 0.023
84.0 0.0 3,012 330.44 0.021
90.0 0.0 2,549 330.37 0.020
96.0 0.0 2,115 330.31 0.019
102.0 0.0 1,709 330.25 0.017
108.0 0.0 1,332 330.20 0.016
114.0 0.0 984 330.14 0.015
120.0 0.0 665
63.0
66.0
69.0
0
Basin B
t Pond Routing
100-yr, 6 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TIC [min]
Intensities, I
100-year [in/hr]
• Peak Discharge, Qp
100-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 6 hour storm
100-year [inches]
Volume of Runoff, V, from 6-hour storm
100-year [inches]
100-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
100-year [minutes]
Time Interval for Routing
. 100-year [minutes]
3.60
3.30
6.90
0.65
5.0
9.12
40.90
B
98.0
61.0
78.7
2.7
5.39
V = ((P-.2S)"2)/(P+.8s)
3.06
1.76
Tp = V/(1.39*Qp)
22.5
2
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
Basin B
Pond Routing
100-yr, 24 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
Tc [min]
Intensities, I
100-year [in/hr]
Peak Discharge, Qp
100-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 24 hour storm
100-year [inches]
Volume of Runoff, V, from 24-hour storm
100-year [inches]
100-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
100-year [minutes]
Time Interval for Routing
• 100-year [minutes]
3.60
3.30
6.90
0.65
5.0
9.12
40.90
B
98.0
61.0
78.7
2.7
7.59
v = ((p-.2S)"2)/(p+.8s)
5.03
2.89
Tp = V/(1.39"Qp)
36.9
2
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
0 BASIN PARAMETERS
•
Riser Barrel Emergency Spillway
12 = Weir length 24 = Dia. barrel (inches) 40 = Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
331.90 =Crest elev. Weir 330 = Invert elev. barrel 340.0 = Crest elev.
z
width of basin
330.0 = Initial elev. water level
Results 100 year 24 hour storm
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
100 22.73 333.26 40.90
•
• ROUTING AND ANALYSIS --100-year 24 hour storm
Outlet Hydraulics
Time Inflow Storage Stage .Outflow Q_orifice Q
[mins] [cfs] [cubic ft] [ft] [cfs] em.spil
0.0 0.0 0 330.00 0.0 0.0 0
2.0 0.3 0 330.00 0.0 0.0 0
4.0 1.2 1 330.00 0.0 0.0 0
6.0 2.6 142 330.02 0.0 0.2 0
8.0 4.6 2 330.00 0.0 0.0 0
10.0 7.0 275 330.04 0.0 0.3 0
12.0 9.8 693 330.10 0.0 0.8 0
14.0 12.9 1,278 330.19 0.0 1.4 0
16.0 16.2 2,050 330.30 0.0 2.3 0
18.0 19.6 3,021 330.44 0.0 3.4 0
20.0 23.1 4,199 330.60 0.0 4.5 0
22.0 26.5 5,585 330.77 0.0 5.8 0
24.0 29.7 7,175 330.97 0.0 7.3 0
26.0 32.7 8,958 331.19 0.0 9.0 0
28.0 35.3 10,918 331.43 0.0 10.8 0
30.0 37.4 13,034 331.67 0.0 12.6 0
32.0 39.1 15,281 331.92 0.2 14.5 0
34.0 40.3 17,619 332.16 5.4 16.3 0
36.0 40.8 19,712 332.37 12.7 17.7 0
38.0 40.8 21,399 332.53 183 18.7 0
• 40.0 40.2 22,726 332.66 19.5 19.5 0
42.0 39.0 23,969 332.79 20.2 20.2 0
44.0 37.3 25,101 332.90 20.8 20.8 0
46.0 35.1 26,092 332.99 21.3 21.3 0
48.0 32.8 26,920 333.08 21.8 21.8 0
50.0 30.6 27,581 333.14 22.1 22.1 0
52.0 28.5 28,089 333.19 22.4 22.4 0
54.0 26.5 28,456 333.23 22.5 22.5 0
56.0 24.7 28,697 333.25 22.7 22.7 0
58.0 23.1 28,822 333.26 22.7 22.7 0
60.0 21.5 28,843 333.26 22.7 22.7 0
62.0 20.0 28,768 333.26 22.7 22.7 0
64.0 18.7 28,609 333.24 22.6 22.6 0
66.0 17.4 28,372 333.22 22.5 22.5 0
68.0 16.2 28,067 333.19 22.3 22.3 0
70.0 15.1 27,699 333.15 22.2 22.2 0
72.0 14.1 27,277 333.11 21.9 21.9 0
74.0 13.1 26,805 333.06 21.7 21.7 0
76.0 12.2 26,291 333.01 21.4 21.4 0
333.3 22.7 < _= maximum 100-yr 24 hour storm
Q_riser
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
5.4
12.7
20.0
26.5
33.1
39.5
45.4
50.5
54.7
58.1
60.5
62.1
63.0
63.1
62.6
61.5
60.0
57.9
55.5
52.8
49.8
46.6
0 Soil Investigation
Pond "B"
A hand auger was used to advance a test hole approximately 30 inches in depth in two
locations of the proposed pond. The soil found appears to be a sandy loam, with a
predominance of quartz material throughout the sample. The soil samples were well
drained.
We recommend a geotechnical engineer, or B&F Consulting be present during
construction of this pond in particular to ascertain whether a lining material (clay) will be
required as the pond is excavated to its proposed depths. The presence of the nearby
stream does indicate groundwater availability at a depth of the invert of the stream.
•
POND C
0
0
Permit Number:
CJ
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin Operation and Maintenance Agreement
of structures, safety of the public, and the removal efficiency of the BMP.
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
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
? does ®does not incorporate a vegetated filter at the outlet.
This system (check one):
? does ® does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
- Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
- No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
- Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
- If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
•
- Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must 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 BMP Trash/ debris is resent. Remove the trash/ debris.
The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to
detention basin 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.
Vegetation is too short or too Maintain vegetation at a height of
long. a roximatel six inches.
Form SW401-Wet Detention Basin O&M-Rev.3
Page 1 of 4
Permit Number:
•
•
E
(to be provided by DWQ)
Drainage Area Number:
BMP element: Potential problem: How I will remediate the problem:
The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the
Swale sediment off-site.
The pipe is cracked or Replace the pipe.
otherwise damaged.
Erosion is occurring in the Regrade the swale if necessary to
swale. smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design depth for possible. Remove the sediment and
sediment storage. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf Best professional practices Prune according to best professional
shoal that pruning is needed practices
to maintain optimal plant
health.
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 to establish the.
ground cover if a soil test indicates
it is necessary.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design sediment possible. Remove the sediment and
storage depth. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over Consult a professional to remove
50% of the area. and control the algal growth.
Cattails, phragmites or other Remove the plants by wiping them
invasive plants cover 50% of with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.3
Page 2 of 4 .
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element: Potential problem: How I will remediate the problem:
The embankment Shrubs have started to grow Remove shrubs immediately.
on the embankment.
Evidence of muskrat or Use traps to remove muskrats and
beaver activity is present. consult a professional to remove
beavers.
A tree has started to grow on Consult a dam safety specialist to
the embankment. remove the tree.
An annual inspection by an Make all needed repairs.
appropriate professional
shows that the embankment
needs repair.
The outlet device Clogging has occurred. Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is damaged Repair or replace the outlet device.
The receiving water Erosion or other signs of Contact the local NC Division of
damage have occurred at the Water Quality Regional Office, or
outlet. the 401 Oversight Unit at 919-733-
1786.
• The measuring device used to determine the sediment elevation shall be such
that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads 316.0 feet in the main pond, the
sediment shall be removed.
When the permanent pool depth reads 320.0 feet in the forebay, the sediment
shall be removed.
BASIN DIAGRAM
ill in the blanks)
•
0 Permanent Pool Elevation 324.0
Sediment Removal . 320.0 ;Pe anen Pool
--------------Volume Sediment Removal Elevation 316.0 Volume
-------------------------------------------- ------
ottom E evaho 318.0 ft Min.
Sediment Bottom Elevation 313.6 1-ft n
Storage Sedimet
Storage
FOREBAY MAIN POND
Form SW401-Wet Detention Basin O&M-Rev.3
Page 3 of 4
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: Stonemont
BMP drainage area number: "C"
Print name: 6/765 JA. J r.
Title: ,Ov?
Address: /* 7i¢.. r4olew cl-- 4A-e-c /t/C
Phony
Signa
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 s =? -_
• . ., cu s _L, , a Notary Public for the State of
VO E , County of e , do hereby certify that
Cc w ?;s t! SVe,S J r personally appeared before me this _L
day of ZCO £f , and acknowledge the due execution of the
forgoing wet detention basin ai enance requirements. Witness my hand and official
seal, 1?-
`l ADg4f
'•?N0TAR? ??.
C?• 'z?
•
-_ AVBLDG =Vr
SEAL
My commission expires y ZOO
Form SW401-Wet Detention Basin O&M-Rev.3
Page 4 of 4
Permit No.
(to be provided by DWQ)
III. REQUIRED ITEMS CHECKLIST
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.
•
•
Pagel Plan
Initials Sheet No.
]Z? 1. Plans (1" 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),
Basin dimensions,
Pretreatment system,
- High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW),
- Overflow device, and
Boundaries of drainage easement.
C D 3 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
Outlet structure with trash rack or similar,
- Maintenance access,
Permanent pool dimensions,
Forebay and main pond with hardened emergency spillway,
Basin cross-section,
Vegetation specification for planting shelf, and
- Filter strip.
3. Section view of the dry detention basin (1" = 20' or larger) showing:
- Side slopes, 3:1 or lower,
- Pretreatment and treatment areas, and
- Inlet and outlet structures.
CD 3.3 I 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
on the plans prior to use as a wet detention basin.
_ ,,- 1 6
Cx 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
CO 36 to verify volume provided.
6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
f t `?- *"4 7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
A 9. A copy of the deed restrictions (if required).
FAY) A 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
Form SW401-Wet Detention Basin-Rev.4
Part III. Required Items Checklist, Page 1 of 1
Permit No.
(to be provided by DWQ)
,?> ??F w Fl rr,9Q
O G
>
• NCaENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part lll) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Stonemont
Contact person Russell Briggs, P.E.
Phone number 919-618-0180
Date 30-Jun-08
Drainage area number "C
II. DESIGN INFORMATION
Site Characteristics
Drainage area 300,564.00 ft2
Impervious area 118,918.80 ft2
% impervious 39.57 %
Design rainfall depth 1.00 in
Storage Volume: Non-SR Waters
Minimum volume required 10,177.00 ft3
Volume provided 11,488.00 ft3
Storage Volume: SR Waters
1-yr, 24-hr runoff depth in
Pre-development 1-yr, 24-hr runoff ft3
`Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Peak Flow Calculations
1-yr, 24-hr rainfall depth 2,89 in
Rational C, pre-development 0.30 (unitless)
Rational C, post-development 0.55 (unitless)
Rainfall intensity: 1-yr, 24-hr storm 4.90 in/hr
Pre-development 1-yr, 24-hr peak flow 10.14 ft3/sec
Post-development 1-yr, 24-hr peak flow 18.60 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control 8.45 ft3/sec
Basin Elevations
Basin bottom elevation 313.60 ft
Sediment cleanout elevation 316.00 ft
Bottom of shelf elevation 323.50 It
Permanent pool elevation 324.00 It
SHWT elevation 320.00 ft
Top of shelf elevation 324.50 ft
Temporary pool elevation 325.30 ft
•
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2
Permit No.
(to be provided by DWQ)
II. DESIGN INFORMATION
Volume and Surface Area Calculations
SA/DA ratio 1.73 (unitless)
•
Surface area at the bottom of shelf 5,155.00 ftz
Volume at the bottom of shelf 17,590.00 ft3
Permanent pool, surface area required 5,199.76 ftz
Permanent pool, surface area provided 6,800.00 ft OK
Permanent pool volume 20,578.00 ft3
Average depth for SA/DA tables 3.03 ft OK
Surface area at the top of shelf 8,640.00 ft2
Volume at the top of shelf 24,438.00 ft3
Forebay volume 4,500.00 ft3
Forebay % of permanent pool volume 21.87 % OK
Temporary pool, surface area provided 9,595.00 ftz
Drawdown Calculations
Treatment volume drawdown time 4.00 days OK
Treatment volume discharge rate 0.50 ft3/s
Pre-development 1-yr, 24-hr discharge 10.14 ft3/s OK
Post-development 1-yr, 24-hr discharge 8.70 ft3/s OK
Additional Information
Diameter of orifice 1 in
Design TSS removal 85 %
Basin side slopes 3.00 :1 OK
Vegetated shelf slope 10.00 :1 OK
Vegetated shelf width 10.00 ft OK
Length of flowpath to width ratio 3.00 :1 OK
Length to width ratio 1.50 :1 OK
Trash rack for overflow & orifice? Y (Y or N) OK
Freeboard provided 1.00 ft OK
• Vegetated filter provided? y (Y or N) OK
Recorded drainage easement provided? y (Y or N) OK
Capures all runoff at ultimate build-out? y (Y or N) OK
Drain mechanism for maintenance or emergencies drain via pump
?J
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2
• Basin "C"
•
Area of Right of way 1.72 acres
Impervious area in street right of way 1.28 acres
Number of lots 17
Typical impervious area per lot (%)
Drive, sidewalk 600 sf
Footprint 3000 sf
Deck 120 sf
3720
Impervious area of lots: 1.45 acres
Total drainage area 6.90 acres
Total impervious area, lots + r/w 2.73
% impervious 40%
Use 40% criteria 40%
SA/DA ratio for 3' depth 1.73%
SA 0.12 acres
Treatment volume
Treatment volume =
V =3630xRox(0.05+0.9xIa)xA
where
V = Volume of runoff to be controlled (ft3)
Ro = Design storm rainfall depth (1")
A = watershed area (ac.)
10177 cubic feet
•
•
Pond C
Average Pond Depth = 3.03 (excludes sediment storage)
Elevation SF Area CF Volume Shelf from e.323.5 to e.324.5
327.5 12349 55827
326 10431 38742
325.3 9595.2 32067 water quality pool
324.5 8640 24438 <-shelf (upper)
324 6800 20578 <-n.pool 20% of NP volume = 4116 cf
323.5 5155 17590 <-shelf (lower) 1543 sf
322 3751 10910
320 2242 4917
318 1143 1532
316 389 0 <-sediment storage elevation (start avg. depth calc here)
315 159 0
314 20 0
313.6 0 0 Sed. Storage depth = 2.4 ft
Forebay Volume
Elevation SF Area CF Volume
326 1644 4953
324 996 2313
322 475 842
320 176 191
318 15 0
Water Quality Volume: 10177 CF (above normal pool)
This volume occurs 1.16 feet above normal pool
Set weir at 1.3' above normal pool
Volume provided = 11488 cubic feet
0
Pond "C"
Pond Routing
1-yr, 24 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TC [min]
Intensities, I
1-year [i n/h r]
• Peak Discharge, Qp
1-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 6 hour storm
1-year [inches]
Volume of Runoff, V, from 6-hour storm
1-year [inches]
1-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
1-year [minutes]
Time Interval for Routing
• 1-year [minutes]
4.17
2.73
6.90
0.55
5.0
4.90
18.60
B
98.0
61.0
75.6
3.2
2.89
v = ((p-.2S)"2)/(p+.8s)
0.92
0.53
Tp = V/(1.39*Qp)
14.9
1
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
• BASIN PARAMETERS
r-?
Riser Barrel Emergency Spillway
12 = Weir length 30 = Dia. barrel (inches) 40 =Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
325.30 =Crest elev. Weir 324 = Invert elev. barrel 327.5 = Crest elev.
324.0 = Initial elev. water level
Results
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
1 8.68 325.66 18.60
0
0 ROUTING AND ANALYSIS - 1-year storm
Time Inflow Storage Stage
[mins] [cfs] [cubic ft] [ft]
0.0 0.0 0 324.00
1.0 0.2 0 324.00
2.0 0.8 12 324.00
3.0 1.8 61 324.01
4.0 3.1 169 324.02
5.0 4.7 356 324.05
6.0 6.5 638 324.08
7.0 8.4 1,028 324.13
8.0 10.4 1,533 324.20
9.0 12.3 2,155 324.28
10.0 14.1 2,892 324.37
11.0 15.6 3,736 324.48
12.0 16.9 4,673 324.59
13.0 17.9 5,688 324.70
14.0 18.4 6,759 324.82
15.0 18.6 7,865 324.94
16.0 18.3 8,980 325.06
17.0 17.7 10,081 325.18
18.0 16.7 11,143 325.30
• 19.0 15.4 12,144 325.40
20.0 14.1 12,993 325.48
21.0 12.9 13,652 325.55
22.0 11.8 14,131 325.60
23.0 10.9 14,456 325.63
24.0 9.9 14,657 325.65
25.0 9.1 14,762 325.66
26.0 8.4 14,795 325.66
27.0 7.7 14,775 325.66
28.0 7.0 14,718 325.66
29.0 6.4 14,634 325.65
30.0 5.9 14,533 325.64
31.0 5.4 14,421 325.63
32.0 4.9 14,302 325.61
33.0 4.5 14,180 325.60
34.0 4.2 14,058 325.59
35.0 3.8 13,936 325.58
36.0 3.5 13,817 325.57
37.0 3.2 13,700 325.55
38.0 2.9 13,588 325.54
325.7
Outflow
[cfs]
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.2
3.1
4.9
6.4
7.5
8.2
8.6
8.7
8.6
8.4
8.1
7.8
7.4
7.0
6.6
6.2
5.8
5.4
5.1
4.7
Outlet Hydraulics
Q_orifice Q Q_riser
em.spil
0.0
0.0
0.0
0.1
0.2
0.5
0.9
1.4
2.1
2.9
4.0
5.1
6.2
7.4
8.6
9.9
11.2
12.5
13.7
14.8
15.7
16.4
16.9
17.2
17.4
17.5
17.6
17.5
17.5
17.4
17.3
17.2
17.0
16.9
16.8
16.7
16.5
16.4
16.3
8.7 < ==maximum 2-yr
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 0.0
0 1.2
0 3.1
0 4.9
0 6.4
0 7.5
0 8.2
0 8.6
0 8.7
0 8.6
0 8.4
0 8.1
0 7.8
0 7.4
0 7.0
0 6.6
0 6.2
0 5.8
0 5.4
0 5.1
0 4.7
• Analysis of time to empty
r?
LJ
Time Inflow Storage Stage Outflow
[hrs] [cfs] [cubic ft] [ft] [cfs]
0.0 0.0 11,154 325.30 0.034
6.0 0.0 10,420 325.22 0.033
12.0 0.0 9,708 325.14 0.032
18.0 0.0 9,016 325.07 0.031
24.0 0.0 8,346 324.99 0.030
30.0 0.0 7,696 324.92 0.029
36.0 0.0 7,068 324.85 0.028
42.0 0.0 6,461 324.79 0.027
48.0 0.0 5,874 324.72 0.026
54.0 0.0 5,309 324.66 0.025
60.0 0.0 4,765 324.60 0.024
66.0 0.0 4,242 324.54 0.023
72.0 0.0 3,740 324.48 0.022
78.0 0.0 3,260 324.42 0.021
84.0 0.0 2,806 324.36 0.020
90.0 0.0 2,376 324.31 0.019
96.0 0.0 1,972 324.26 0.018
102.0 0.0 1,593 324.21 0.016
108.0 0.0 1,239 324.16 0.015
114.0 0.0 911 324.12 0.014
120.0 0.0 608
63.0
66.0
69.0
0
• Pon "C"
Pond Routing
100-yr, 6 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TIC [min]
Intensities, I
100-year [in/hr]
Peak Discharge, Qp
100-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 6 hour storm
100-year [inches]
Volume of Runoff, V, from 6-hour storm
100-year [inches]
100-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
100-year [minutes]
Time Interval for Routing
100-year [minutes]
B
4.17
2.73
6.90
0.55
5.0
9.12
34.61
98.0
61.0
75.6
3.2
5.39
v = ((P-.2S)"2)/(P+.8s)
2.83
1.63
Tp = V/(1.39*Qp)
24.5
2
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
0 BASIN PARAMETERS
•
Riser Barrel Emergency Spillway
12 = Weir length 30 = Dia. barrel (inches) 40 =Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
325.15 =Crest elev. Weir 324 = Invert elev. barrel 327.5 =Crest elev.
324.0 = Initial elev. water level
Results 100-year 6-hour storm
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
100 26.23 326.49 34.61
0
ROUTING AND ANALYSIS --100-year, 6 hour storm
Outlet Hydraulics
t
Time Inflow Storage Stage Outflow Q_orifice Q
[mins] [cfs] [cubic ft] IN [cfs] em.spil
0.0 0.0 0 324.00 0.0 0.0 0
2.0 0.6 0 324.00 0.0 0.0 0
4.0 2.2 68 324.01 0.0 0.1 0
6.0 4.9 334 324.04 0.0 0.5 0
8.0 8.3 918 324.12 0.0 1.3 0
10.0 12.4 1,915 324.25 0.0 2.6 0
12.0 16.7 3,398 324.44 0.0 4.6 0
14.0 21.1 5,404 324.67 0.0 7.1 0
16.0 25.3 7,937 324.95 0.0 10.0 0
18.0 28.9 10,970 325.28 0.0 13.5 0
20.0 31.8 14,438 325.63 7.4 17.2 0
22.0 33.7 17,358 325.92 19.3 20.3 0
24.0 34.6 19,086 326.08 22.0 22.0 0
26.0 34.3 20,599 326.21 23.4 23.4 0
28.0 32.9 21,912 326.33 24.6 24.6 0
30.0 30.5 22,914 326.42 25.5 25.5 0
32.0 27.6 23,518 326.47 26.1 26.1 0
34.0 24.8 23,697 326.49 26.2 26.2 0
36.0 22.3 23,523 326.47 26.1 26.1 0
38.0 20.1 23,070 326.43 25.7 25.7 0
40.0 18.0 22,398 326.37 25.0 25.0 0
42.0 16.2 21,559 326.30 24.3 24.3 0
44.0 14.6 20,595 326.21 23.4 23.4 0
46.0 13.1 19,543 326.12 22.4 22.4 0
48.0 11.8 18,431 326.02 21.4 21.4 0
50.0 10.6 17,285 325.91 19.0 20.2 0
52.0 9.5 16,282 325.81 14.5 19.1 0
54.0 8.6 15,687 325.75 12.1 18.5 0
56.0 7.7 15,270 325.71 10.4 18.1 0
58.0 6.9 14,945 325.68 9.2 17.7 0
60.0 6.3 14,672 325.65 8.2 17.4 0
62.0 5.6 14,432 325.63 7.4 17.2 0
64.0 5.1 14,217 325.61 6.7 16.9 0
66.0 4.5 14,020 325.59 6.1 16.7 0
68.0 4.1 13,838 325.57 5.5 16.5 0
70.0 3.7 13,669 325.55 5.0 16.4 0
72.0 3.3 13,512 325.54 4.5 16.2 0
74.0 3.0 13,366 325.52 4.1 16.1 0
76.0 2.7 13,230 325.51 3.7 15.9 0
Q_riser
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
7.4
19.3
27.3
34.6
41.3
46.8
50.1
51.1
50.2
47.6
43.9
39.5
34.6
29.5
24.4
19.0
14.5
12.1
10.4
9.2
8.2
7.4
6.7
6.1
5.5
5.0
4.5
4.1
3.7
326.5 26.2 < _= maximum 100-yr 6 hr storm
• Pon "C"
Pond Routing
100-yr, 24 hour storm
Stonemont
HYDROGRAPH PARAMETERS
Item
Drainage Area
Area Type
Lawn, Landscape [acres]
Impervious [acres]
Drainage Area [acres]
Rational C
Composite Rational C
Time of Concentration, Tc
TC [min]
Intensities, I
100-year [in/hr]
• Peak Discharge, Qp
100-year [cfs]
Curve Number, CN
Hydrologic Soil Group
Impervious CN
Lawn, Landscaped CN
Composite CN
S
Precipitation Amount, P for 24 hour storm
100-year [inches]
Volume of Runoff, V, from 24-hour storm
100-year [inches]
100-year [acre-feet]
Time-to-Peak, Tp (for use in routing)
100-year [minutes]
Time Interval for Routing
• 100-year [minutes]
4.17
2.73
6.90
0.55
5.0
9.12
34.61
B
98.0
61.0
75.6
3.2
7.59
v = ((p-.2S)^2)/(p+.8s)
4.75
2.73
Tp = V/(1.39"Qp)
41.2
2
B&F Consulting, Inc.
2805 Tobermory Lane
Raleigh, NC 27606
(919) 618-0180
• BASIN PARAMETERS
Riser Barrel Emergency Spillway
12 = Weir length 30 = Dia. barrel (inches) 40 =Length
3.3 = Cw weir 0.6 = Cd barrel 3.00 = Cw
325.15 =Crest elev. Weir 324 = Invert elev. barrel 327.5 =Crest elev.
324.0 = Initial elev. water level
Results 100-year, 24-hour storm
Event Post Development
With Controls No Control
Peak Peak Peak
Discharge Elevation Discharge
[cfs] [cfs]
100 29.28 326.79 34.61
0
0 ROUTING AND ANALYSIS --100-year, 24 hour storm
•
Time Inflow Storage
[mins] [cfs] [cubic ft]
0.0 0.0 0
2.0 0.2 0
4.0 0.8 24
6.0 1.8 120
8.0 3.1 334
10.0 4.8 709
12.0 6.8 1,284
14.0 9.0 2,096
16.0 11.4 3,172
18.0 13.9 4,536
20.0 16.5 6,205
22.0 19.2 8,189
24.0 21.8 10,488
26.0 24.2 13,099
28.0 26.6 15,602
30.0 28.7 17,384
32.0 30.5 18,495
34.0 32.1 19,590
36.0 33.3 20,748
38.0 34.1 21,921
40.0 34.5 23,063
42.0 34.6 24,130
44.0 34.2 25,083
46.0 33.5 25,889
48.0 32.3 26,519
50.0 30.8 26,948
52.0 29.1 27,156
54.0 27.3 27,133
56.0 25.6 26,899
58.0 24.1 26,488
60.0 22.6 25,930
62.0 21.2 25,253
64.0 19.9 24,481
66.0 18.7 23,637
68.0 17.6 22,739
70.0 16.5 21,804
72.0 15.5 20,844
74.0 14.5 19,869
76.0 13.6 18,890
Stage Outflow
IN [cfs]
Outlet Hydraulics
Q_orifice Q Q_riser
em.spil
324.00 0.0 0.0 0
324.00 0.0 0.0 0
324.00 0.0 0.0 0
324.02 0.0 0.2 0
324.04 0.0 0.5 0
324.09 0.0 1.0 0
324.17 0.0 1.8 0
324.27 0.0 2.9 0
324.41 0.0 4.3 0
324.57 0.0 6.1 0
324.76 0.0 8.0 0
324.97 0.0 10.3 0
325.23 0.0 12.9 0
325.49 3.4 15.8 0
325.74 11.7 18.4 0
325.92 19.4 20.3 0
326.03 21.4 21.4 0
326.13 22.4 22.4 0
326.23 23.5 23.5 0
326.33 24.6 24.6 0
326.43 25.6 25.6 0
326.52 26.6 26.6 0
326.61 27.5 27.5 0
326.68 28.2 28.2 0
326.73 28.7 28.7 0
326.77 29.1 29.1 0
326.79 29.3 29.3 0
326.79 29.3 29.3 0
326.77 29.1 29.1 0
326.73 28.7 28.7 0
326.68 28.2 28.2 0
326.62 27.6 27.6 0
326.55 27.0 27.0 0
326.48 26.2 26.2 0
326.40 25.3 25.3 0
326.32 24.5 24.5 0
326.24 23.6 23.6 0
326.15 22.7 22.7 0
326.06 21.8 21.8 0
326.8 29.3 < == maximum 100-yr 24-hr storm
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.4
11.7
19.4
24.7
29.7
35.3
41.4
47.6
53.6
59.2
64.1
68.0
70.7
72.0
71.8
70.4
67.8
64.3
60.2
55.7
50.8
45.8
40.8
35.8
31.0
26.4
0
Soil Investigation
Pond "C"
A hand auger was used to advance a test hole approximately 30 inches in depth in two
locations of the proposed pond. The soil found appears to be a sandy loam, with a
predominance of quartz material throughout the sample. The soil samples were well
drained.
We recommend a geotechnical engineer, or B&F Consulting be present during
construction of this pond in particular to ascertain whether a lining material (clay) will be
required as the pond is excavated to its proposed depths. The presence of the nearby
stream does indicate groundwater availability at a depth of the invert of the stream.
•
r1
U
Level Spreader Calculations, Worksheets
and
O&M Agreements
40
Permit Number:
(to be provided by DWQ)
Drainage Area Number: r-
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 an 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: Stonemont
BMP drainage area number:- 4
Print name: Curtis Jones, Jr.
Title: member
Address: 140 Towerview Court, Cary NC
?. Phon
Sigm
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, P1.5-Ty W"t nn a Notary Public for the State of
?lvA t'ti Ltd ha , County of do hereby certify that
(1--ot 5 ?hncs '_'I?' • personally appeared before me this 9 7d
day of Zbo , and acknowledge the due execution of the
forgoing filter strip, riparian buffer, and/or level spreader maintenance requirements.
My commission expireswr- Z 7 ?,p/ V
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 of 3
Witness my hand and official seal,
DWQ Project
is DIVISION OF WATER QUALITY - LEVEL SPREADER WORKSHEET (112007)
1. PROJECT INFORMATION (please complete the following information):
Project Name : _`?7?bA./CNO,t_/7"
Contact Person: TS us SEL _ e_ Phone Number:
Level Spreader ID: _F E
Level Spreader Length /D ft
Drainage Area O.31 ac.
Impervious Area ?, L 5 ac.
Forebay Area cu ft
Maximum Filter Strip/Buffer Slope -5_ %
grass
(perpendicular to flow)
(on-site and off-site drainage to the level spreader)
(on-site and off-site drainage to the level spreader)
(0.2% of the contributing impervious surface area)
(6% for forested, leaf littler cover, 8% for thick ground cover
Max. Discharge from 1"7Hr Storm O 3 cfs
Max. Discharge to Level Spreader cfs
Filter Strip/ Zone 2 Buffer Vegetation cam (thick ground cover or grass; canopied forest with leaf litter
groundcover)
Pre-treatment or Bypass Method Used
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
• requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Applicants Initials
---1?,_Project Site was visited prior to designing level spreader.
-Date of the Site visit. PLEASE ATTACH TIME-DATED DIGITAL PHOTO OF EXISTING BUFFER CONDITIONS.
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 65 ft per cfs in canopied forest with leaf
litter for 50-foot buffer; 50 ft per cfs for 100-foot buffer, or 40 ft. per cfs for 150-foot buffer.
S! Pre-Formed Scour Holes are on flat slopes only.
-WA No structures are located in protected buffers (must meet no practical alternatives criteria).
Design Alternative (if any) and Bypass method used:
----Bypass conveyance method is specified and plan details and calculations are provided.
Alternative design option is specified and plan details and calculations are provided.
Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
No structures are located in protected buffers.
Plan details for the bypass and outlets are provided.
E The operation and maintenance agreement includes annual erosion and vegetation repair.
The operation and maintenance agreement signed and notarized by the responsible party is provided.'
0
•
,f
•
0
10010 SF
FFE=329.0
PAD T01 F RAP MN \\?
"E$2 R
N SAY so 108
\
AyARRiEE?Af s. c 10010 SF
32'X9 31. TH c. MIN FFE=329.5 -
'2lY' SPILL WAY 109
.S. 1 D 11419 SF j
6,112 SF MIN FE=329,5
11302
?? ' TANDAR
CONSTRUCn
NTRANCE . . .FUTURE. 5.0.
. CL-ROW DON,
\ '. WHEN ADJAC
-` 12U ?\ 11291 SF Z \ \ ` / .` ,
19 ?.
`.` B 10894 F \ /
o
Al-
-? Z110Z", , Z- i 14 / 10274 SF Gay r cy?
?MID, lk?
3A
14'704 IN FFE= 6.0 ?fi
. SED BASIN 10 fo
DRAINA .AREA: 0.28 AC
DENUDED 0.28 AC - ON
SED. STORA .580 CF 't-
49''18'X3.5'. TN Wt ILLWAY rImMER SF D2
MIN FE=33>5
TEMP. SED BASIN RY
NAOE AREA: QA AC-1
26 .1 AC
0 AREA
I ..
TOR uw szo
4 01 43 SF 10,006 SF
MIN FFE
=333.5 MH 116
i
112
13148 SF;
10903 F//
\
IH A`F\` MIN FFE \
??••??CC??-- 1 =334.0
51 13
TEMPORARY
10
MIN 000ESF BARRICADE W/
i MFN =335.0 \ `\ TORS SIGNAGE
Tea 5 114
\ / WEI PIPE. GeF ??, . AGe \? ::::::. ' •.. OLI SF
E 2 G ?j ? .:::++i:%. FFE
Y IN 20 E E G' J `\
S 00
Fa F.:. 1536 \
L 7
SED BASIN 2
.JORAINAGE AREA: 2.08 AC
I-' NOTE TH' / AA? ippIUDED AREA. 1.42 AC
\ / K 11ibbEEEEDDDDD STORACE: 1835 CF
FBI (CAPE FE F 1? h 1. 39'X1 18X3.5' DEPTH
WILL BE LEFT UNDISTURBED. 10` SPILLWAY SHOWN
THIS IS THE 20' ON EITHER SIDE ? NO SKIMMER PROMDED
OF THE STREAM BANK EDGE, MHTEXANNA PA U,
RECREATI QN
B Y WILL
S l AREA 1 B AREA = 13.561 AC
' i ALKING TRAILS/PICNIC AREA \ LAND USE. S. F. H04
B 98,639 SF \
l ° I FLOOD
Q B P ` `\
EL. 3
! ?1 N 1 O. TEMP. ;'BASIN 30J
DRAINACE AREA: 5.15 AC
g34 DENUDED AREA: 251 F
S
J m I ? SEO. STORAGE: 2451 CF b ? PJ \ '
46,X139'X3.5' DEPTH
J I T20' SPILLWAY SHO 'y0
PRgNDE %gMM5A Qw , F
124 ?j
11976 SF r?,o ; ((,?, ?F
O
IN FFE='349.0
v?/ ,/CN?p? \\
\ 1' 'A, Q? ^3AQ
<IV
125
15861 SF \ \
J IN FFE=352.0
11
f
126
\7465 SF
/
-7
16789 SF % 3
Permit Number:
(to be provided b QWQ)
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 pefformed 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 an 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: Stonemont
BMP drainage area number: _[??-:5 J
Print name: Curtis Jones, Jr.
Title: member
Address:, 140 Tower-view Court, CM, NQ
,:Ph6r
Sign,
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.
1, PUTY a Notary Public for the State of
1?1 t`? t-APD? Irea , County of ,cam , do hereby certify that
U? hnec ? . personally appeared before me this 9 7d
day of .. ? ZpD , and acknowledge the due execution of the
forgoing filter strip, riparian buffer, and/or level spreader maintenance requirements.
Witness my hand and official seal,
My commission expires dw,?Ir Z7 ? o,1V
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 of 3
DWQ Project
•
DIVISION OF WATER QUALITY - LEVEL SPREADER WORKSHEET (1/2007)
I. PROJECT INFORMATION (please complete the following information):
Project Name 51r4<-9641
Contact Person: _ 7?5 %F?_ Phone Number:
Level Spreader ID: FCs S
Level Spreader Length ,/D ft.
Drainage Area 0,44 ac.
Impervious Area d . 1 95 ac.
Forebay Area 1 cu ft
Maximum Filter Strip/Buffer Slope ¢ %
grass
Max. Discharge from 1°/Hr Storm 02 cfs
Max. Discharge to Level Spreader O cfs
Filter Strip/ Zone 2 Buffer Vegetation u Lan,-
Pre-treatment or Bypass Method Used ?46
II. REQUIRED ITEMS CHECKLIST
(perpendicular to flow)
(on-site and off-site drainage to the level spreader)
(on-site and off-site drainage to the level spreader)
(0.2% of the contributing impervious surface area)
(6% for forested, leaf littler cover, 8% for thick ground cover
(thick ground cover or grass; canopied forest with leaf litter
groundcover)
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
• a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details,' a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
A_ pplicants Initials
Project Site was visited prior to designing level spreader.
Date of the Site visit. PLEASE ATTACH TIME-DATED DIGITAL PHOTO OF EXISTING BUFFER CONDITIONS.
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 65 ft per cfs in canopied forest with leaf
C litter for 50-foot buffer; 50 ft per cfs for 100-foot buffer, or 40 ft. per cfs for 150-foot buffer.
l 4 ?f+R Pre-Formed Scour Holes are on flat slopes only.
No structures are located in protected buffers (must meet no practical alternatives criteria).
Design Alternative (if any) and Bypass method used:
.?' Bypass conveyance method is specified and plan details and calculations are provided.
Alternative design option is specified and plan details and calculations are provided.
_ Z?ld Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
-__LT•B No structures are located in protected buffers.
Plan details for the bypass and outlets are provided.
The operation and maintenance agreement includes annual erosion and vegetation repair.
The operation and maintenance agreement signed and notarized by the responsible party is provided.'
•
in
'J1
'U
•
0
\Iumr- JIAIIVN -<I I'll r.
„ W 1566 Sv „a? -'r -
551
AREA DEEDED TO .74 MH
7 25 2J
H'Q .LY SPRINGS N 07-262J"
¢7529 SF
EES 8. B C11Ap?NEL
W/ CONC. WEIR. 10' %tIR \ \
LEVEL SPREAD. AND FES8
FOMASI IN 20' EASEM i ° , \? !• \. i i
230 \ s R. ,?o
2
3 F 15047 SF , D NTp?P. SED 8AS8V 9?? v?zi 1 0 5
NET. 14846 SF / OE AREA: 0.4AAC (? i0 1192 SF
? D UDED AREA: 0,42 WC \ P\ fV?
MIN FFE=323. . STORAGE: Tao w IN FFE=328.0
i 8 TM
40SSPILWAY 1, O p ?
231 1 OE
14975 SF 10010
j NET: 14872 SF MIN FFE
vl MIN FF'E=323.5 =328.5
36 \ `- B +
Na M O ?L
4 TEMPI AREA 0A? A ! \\ W/ EL FF
ENUDEO AREA 0.44 AC
232 SEO' STORAGE: 810 CF I '! B CHANNEL 'c
fES2
20'%87'X3:5' DEPTH I W( C. ."PIPE & IM
4' SPILLWAY SHOWN I
17690 SF VEL AND 13 CF \ \ C`P PAY
NO SKIMMER PROVIDED I FOREBAY I 2q EASEMENT \\ m: \\\ ` FS :5+ !. BAY
D
MIN FFE=324.5 1 \ \\\ :
l \ D D. AREA: 0. .88
p
I I \\ 00\ ?? 32'%9 3.3' DEPTH
245 ?0' SPILLWAY
20898 SF 0. s,
' s'
233 MIN FFE=325.0 i 246
S??°??A 6112 SF
MIN 8608 SF • \` ??`?e qi4 `.\` ?' ro
SF 20804 SF i I 1
i _
NET.- 1623 58 \ \0
I 1 `MIN FFEFE=327.0 .0
MH E2 UT1$SS??
'BYPASS CHANNEL t
244C. 9 W/ CONR.
}$ PIPE AND 10' ER 11 ,? \\ C S
LEVEL SPREADER.
14309 SF ; MH 247
?qM
3 0
3.
DRAT AGE A EA::
BASIN 5 224 AC E1 16369 SF
DENUDED A:0.54 AC
sE0.-_. I NET: 16348 SF
ei?u Y ?? _a MIN FFE=328.0
NO SKIMM RPRONDED + \
40 241 243
'F ?10 SF 12110 SF 10010 SF 248
I? 11179 SF
a
-yr f 4
P. AMAGE SED BASIN AREA: POND 'a" 00 ?• '/ /
8.90 AC BO
• -""-^ ! 1 7 X66. SF ?epDENUDEO AREA 2.74 AC
j 53'25' SPILLWAYPTM
14-70,
G MIN FFE
MH (,'2 DRAINA AREA: 0N .2a AC
' CBS 25 r
DENUDED : 0.2e Ac
SED. STINtA 580 CF
205 49'X18'X3.5' 1H
ILLWAY
207 10010 S 10 06
204 203 I MER
10010 S 202 13138 SF
10010 SF 10010 SF 20 10394 SF 15068 SF )•
----
S 0322'19 "W --??. rS-rMM6-'ER E7ER ------------
769. 19 ?
? PORARY
/ RICADE w/j 3363 S /
i OH GNAGE !
! I
1,34
11200 SF
SO, 133
mw4%4 11200 Sf?
_ Hol FAl1Q A/ /Q n F) r- K I / . , A:h oy ay -7,
1 7 // ???, i VdIN
Permit Number:
(to be provided by DW )
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) clog ed. of an sediment off-site.
The flow splitter device is Make any necessary repairs or
damaged. replace if damage is too large for
re air.
•
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
DWQ Project
• DIVISION OF WATER QUALITY - LEVEL SPREADER WORKSHEET (1/2007)
I. PROJECT INFORMATION (please
Project Name : ! ThA.1.?
Contact Person: Ru%SFs
the following information):
Level Spreader ID: -5;6 6 7
Level Spreader Length 10 ft
Drainage Area 0,54 ac.
Impervious Area O. i fi3 ac.
Forebay Area
Maximum Filter Strip/Buffer Slope ? o ft.
grass
Phone Number:
(perpendicular to flow)
(on-site and off-site drainage to the level spreader)
(on-site and off-site drainage to the level spreader)
(0.2% of the contributing impervious surface area)
(6% for forested, leaf littler cover, 8% for thick ground cover
Max. Discharge from 1 '/Hr Storm 0.3 cfs
Max. Discharge to Level Spreader C9. cfs
Filter Strip/ Zone 2 Buffer Vegetation 64)W- (thick ground cover or grass; canopied forest with leaf litter
groundcover)
Pre-treatment or Bypass Method Used
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, '4 detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Applicants Initials
? G?" Project Site was visited prior to designing level spreader.
i 7 bg Date of the Site visit. PLEASE ATTACH TIME-DATED DIGITAL PHOTO OF EXISTING BUFFER CONDITIONS.
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 65 ft per cfs in canopied forest with leaf
litter for 50-foot buffer; 50 ft per cfs for 100-foot buffer, or 40 ft. per cfs for 150-foot buffer.
Pre-Formed Scour Holes are on flat slopes only.
No structures are located in protected buffers (must meet no practical alternatives criteria).
Design Alternative (if any) and Bypass method used:
Bypass conveyance method is specified and plan details and calculations are provided.
Alternative design option is specified and plan details and calculations are provided.
zzR Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
-- L? -No structures are located in protected buffers.
_1EE -Plan details for the bypass and outlets are provided.
The operation and maintenance agreement includes annual erosion and vegetation repair.
The operation and maintenance agreement signed and notarized by the responsible party is provided.'
0
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: Stonemont
BMP drainage area number: F 7
Print name: Curtis Jones, Jr.
Title: member
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, 15Ty L • Inn f? , a Notary Public for the State of
)]a/ t? t-r4?o? /rte , County of do hereby certify that
?Ur his ..?hr?cs JTr • personally appeared before me this 9 7W
day of , _Z008, and acknowledge the due execution of the
forgoing filter strip, riparian buffer, and/or level spreader maintenance requirements.
• My commission expires - Z ? Q/ D
i
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 of 3
Address: 140 Towerview Court, CM, NQ
Witness my hand and official seal,
L41VG i). m??
20' ON EITHER SIDE OF THE STREAM BAN
t \ \
NOTE THAT THE DOWNSTREAM
\\ ?\ PROPERTY LINE FLOOD ELEVATION
/? \ \ IS BASED ON FUTURE CONDITIONS
AND IS INTERPOLATED FROM
(9 / ?'?' \ \ UPSTREAM AND DOWNSTREAM
FEMA CROSS SECTIONS
? to ,p F,p \?p?`\\\ \\ e G'(
<s;\ THE OLl t
/ P. SED BASIN.. s\ ?\\
4 R NAGE AREA: 0.54 c, O
-° 1 UDED AREA: 0.34 AC 'n \l "?9\ \\ Q
\ LS p
11 M , 88 ST 9 \` \ \ 9?(n??\\ ??? D.U.
1 10
1 EE BYPASS ANNd LAND
? O G W/"" :ANC. WEIR PIPE a f ?\
LEVE7_ S':REAO. AND IB CF \ \ \
0 \ e"FOREBAY IN 20' EASEMENT \ \?\ \
i
9v/ ?`` \ 16461 SF
NET- SF'/ Ciy ?y4+ i t
222 \ MIN FFE=319.
16983 SF 224 /T: 12180 SF 16844 SF
E .-
//MIN FFE=322.0 - NET: 11609 SF \ 3` '
MIN FFE=321.5 \ ?? \ 12' WIDE
??CB \ `? ?\ M \ 8" ABC DRIVE
TO PUMP STAT10
` MH. \\'QP E N F1 \?` ?\ \ . ? WITHIN .40' ESM"
SEE ENLARGEMENT I
W21 225 SPACE 2A \\ o ? \
?p \ 2 2
MINA FFE=323.0 10532 SF \
FHB BG, ???,
I 1 MIN FFE=322.0 208,06), SF
PUMP STATION G?? r
AREA DEEDED TO FP \ ??o? ??? .
SLY SPRINGS
220 4,752,r SF
10010 SF 226 \
` W S CO8. 8 NC.RE . Nr :HEIR \
MIN FFE=324.0 WEIR
' 1 10010 SF
vEl SPAO. AND .FESB
FOREBAY IN 20' EASO /
TEMP.SED BASML 9
. 2 2 7 229 230
21C
15047 SF , o Auk AREA: AREA: o 0. Nc
100101 13330 SF NET: 14646 SF 7 ?
. SEO BASIN 7 MIN FIFE ` 10010 SF ' STORAGE: Teo CF
0.30 Ac_ I' MIN FFE=323. ..STORAGE- DEPTH 1
`8'30'110'-Q SPIKIM MLLWAYER
$TORAGE: 590.CF I r j 0 S ?1yF??
17'X3.5' DEPTH 231
4! Ol
4' SPILLWAY
NO SKIMMER/ I -
?, 228 14975 SF
1306 SF -- / NET: 14872 SF
N FFE a 11306 SF
MIN FFE=323.5
' _9- •7
- I - 31 TEMP. SEO BASIN 4 1' \
AINAGE AREA: 0.44 AC
RA r H - - UDED AREA., 0.44 AC
B
O SM. STORAGE: 810 CF- .I ?I.W •. R. PIPPEE k 1
-- =- S 2 3 2 '20'Xd1 %3.3' DEPTH 1 , - AND 13 C
4' SPILLWAY SHOWN 1 . 1 FORE13AY 2q EASEIM
17690 SF NO SKIMMER PROVIDED
<- 9 MIN FfE=324:5
I ' 1 \
2.1 /T 245 1
IN oo I 20898 SF ' 246
M
I ; FFE6 330.0 r 1
T ABLE SF I L 3 6 I 235 234 Z Z3 MIN FFE=325.0 ) 18608 SF.
INS =30.0 I! I 11976 SE 12110 SF 12110 SF 23 1 NET: 16258 SF
( 20804 SF , MIN FFE=327.0
1nLANDS10225 SF
NET: 10049 SF 1 ! ,/ C
L D H A E 2 244 16 --' 24
33o0 ?1 J 4 I BANS 14309 SF MH 1636
11226 SF ?u?NRACE 2.24 Ac NET: 16:
NET. 10041 SF D A. ENUOEO 0.54 AC MIN FFE:
., 1 aq I I SED. STIR -
31'X93'X .9' DEPTH
. t lYI _ r
8' SPILLAY SHOWN
•
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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 rernediate 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 an sediment off-site.
The flow splitter device is Make any necessary repairs or
damaged. replace if damage is too large for
repair.
C7
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 1 of 3
C]
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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: Stonemont
BMP drainage area number: ?C !
Print name: Curtis Jones. Jr.
Title: member
Address: 140 Towerview Court, Cary, NC
Phone
Signat
Date:_ W 9 /U6
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, ?i.5-ry L. P &Canne fl , a Notary Public for the State of
?CJ' 4 at,21 /ha- , County of ke , do hereby certify that
(fUt h s 'Tt . personally appeared before me this 9 ?d
day of 2!6) , and acknowledge the due execution of the
forgoing filter strip, riparian buffer, and/or level spreader maintenance requirements.
• My commission expires410)6w,?Ir Z rT 2 D/ a
i
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 of 3
Witness my hand and official seal,
DWQ Project No.
0 DIVISION OF WATER QUALITY - LEVEL SPREADER WORKSHEET (1/2007)
1. PROJECT INFORMATION (please
Project Name : 5 r7d) c-
Contact Person: Rus SFt
Level Spreader ID: 1=j?6 P.
the following information):
Level Spreader Length /O ftDrainage Area O . Z ac.
Impervious Area , l ac.
Forebay Area cu ft
Maximum Filter Strip/Buffer Slope %
grass
Phone Number:
(perpendicular to flow)
(on-site and off-site drainage to the level spreader)
(on-site and off-site drainage to the level spreader)
(0.2% of the contributing impervious surface area)
(6% for forested, leaf littler cover, 8% for thick ground cover
Max. Discharge from 1VHr Storm d ),z cfs
Max. Discharge to Level Spreader 0.14 cfs
Filter Strip/ Zone 2 Buffer Vegetation C AdT (thick ground cover or grass; canopied forest with leaf litter
groundcover)
Pre-treatment or Bypass Method Used S
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Applicants Initials
-.._Project Site was visited prior to designing level spreader.
-Date of the Site visit. PLEASE ATTACH TIME-DATED DIGITAL PHOTO OF EXISTING BUFFER CONDITIONS.
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 65 ft per cfs in canopied forest with leaf
litter for 50-foot buffer; 50 ft per cfs for 100-foot buffer, or 40 ft. per cfs for 150-foot buffer.
APre-Formed Scour Holes are on flat slopes only.
fj, No structures are located in protected buffers (must meet no practical alternatives criteria).
Design Alternative (if any) and Bypass method used:
? Bypass conveyance method is specified and plan details and calculations are provided.
Alternative design option is specified and plan details and calculations are provided.
,j Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
,B No structures are located in protected buffers.
Plan details for the bypass and outlets are provided.
The operation and maintenance agreement includes annual erosion and vegetation repair.
The operation and maintenance agreement signed and notarized by the responsible party is provided.'
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16 461 SF
11Z 'NET- 13028 SF//
IN FFE=319. i \? Y ?0 c?L ?6l ?\ v' i
? 16983 SF \ \ cS?
224 ?pET: 12180 SF 16844 SF
'MIN FFE=322.0 NET: 11609 SF
MIN FFE=321.5 \
12' W
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MH. TO PUMP
WITHIN 4C
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10532 SF / 225 SPACE 2A \\ o? ?,, ;
MIN FFE=323.0 10532 SF
! ( L MIN FFE=322.0 208,06 ?. ` ?GOy S'S ,?1
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10010 SF 226 'i Z529 SF
MIN FFE=324.0 r 10010 SF w coNa WfiR,N?10
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1 SPREAD. AND FE
FOREBAY IN 20' EASEME i S -
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219 230
229 TEMP.D 9ASML
10010 SF 22 15047 SF / D AINAGE AREA: 0.421AC
TEMP. SED BASIN 7 MIN FFE J ( 0010 SF 13. 30 SF NET: 14846 SF o uDEO AREA: 0.42 nc
• 0.30 AC_ •Q ' 1 MIN FFE=323. STORAGE: 780 CF \\\
DFD AR 630-AC i 6 'X20 X3.5' DEPTH \ y,R,c1
STORAGE: 590 CF
4' SPILLWAY V"
50'X17'X3.5' DEPTH
4' SPILLWAY/ ?' ' ?^ ? 0 SKIMMERJ•(.
NO SKIMMERZ I 8 I 228 23
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1306 SF 14975 SF BLS n
N FFE o 11306 SF NET: 14872 SF
7,- MIN FFE=323.5
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S'RF' 0 UDED AREA: 0.44 AC I CHAN
p _ SM. STORAGE: 810 OF I W 8 PIPE
? ? 232 2WX61'X3.5' DEPTH.. I
14' SPILLWAY SHOWN I fOREBAY '2 ' CAND I
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7690 SF NO SKIMMER PROVIDED
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2 I ?7 ( I 7 MIN FFE=324:5
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SF 245
MIN FFE F 30.0 ? 2 898 SF j
g ATMWE ? I 1 l9 3 6F 235 234 233 MIN FFE=325.0 i I 246 ? ? TT j I 12110 SF i t 18608 SS
?acnoNAL 12110 SF 20804 'SF I NET. 162 6258 SF
r 10225 SF MIN FFE=327.0
NE.: 100,49 SF + r B
I CB\
MIN FFE ?1 H A E 2 244 18
5 2
=330.011226 SF I I 14309 SF t1 MH
1 \ 1631
NET: 10041 SF ( BASIN s E1
DRAINA A
GE 2.24 AC
?. , DENUDED A. 0.54 AC NET: 11
SED.. srOR MIN FFI
BAY "I1 31'X93 'X 5' DEPTH
i 8' SPILL AY SHOWN
IN FFE 214 LJ `? 238 No SKIM PROVIDED
IN FF 10, 1 SF ? , 1T976 SF 12110 SF 239 240 24 1 2 4 3 24.
12110 SF 10010 SF ( I
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10000 SF +
12110 ,SF 1
2110 SF 11179 S
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MIN FFE _ ! ! j
=334.5 213 I i ( Jill.
10010 SF I i `? q
o NET: 10008 SF M t SFm L "
F 11066 SF
212
11516 SF 1 I ° _ -- -
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NET: 10058 SF
MIN FFE=336.0 , ?_-- CMH1 C2
B 25 210 209 2`? r ? --=-?:
211 1081 SF 10010 S 8 207 206
i •12707 SF i 10010 S 10010 S 10010 S 10010 s 204 203 202
-j NET: 10688 SF , TEMPORARY / 10010 SF 10010 SF 10394 SF
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