HomeMy WebLinkAboutSW8000505_HISTORICAL FILE_20000816 (2)STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW8 00 0 S 0 5
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
Z000 09 16
YYYYMMDD
State of North Carolina
Department of Environment
and Natural Resources
Wilmington Regional Office
James B. Hunt, Jr., Governor
Bill Holman, Secretary
Division of Water Quality
Mr. Ernest D. Hackney, General Partner
1st Wilmington Properties
PO Box 3442
Wilmington, NC 28406
Dear Mr. Hackney:
1�
NCDENR
NORTH CAROUNA DEPARTMENT OF
ENVIRONMENT AND N/ uRA REsouROEs
August 16, 2000
Subject: Permit No. SW8 000505
Ashcroft at The Commons
High Density Subdivision Stormwater Project
Onslow County
The Wilmington Regional Office received a complete Stormwater Management Permit Application for Ashcroft
at The Commons on July 14, 2000. Staff review of the plans and specifications has determined that the project, as
proposed, will comply with the Stormwater Regulations set forth in Title 15A NCAC 2H.1000. We are forwarding
Pen -nit No. SW8 000505, dated August 16, 2000, for the construction of the project, Ashcroft at The Commons.
This permit shall be effective from the date of issuance until August 16, 2010, and shall be subject to the conditions
and limitations as specified therein. Please pay special attention to the Operation and Maintenance requirements
in this permit. Failure to establish an adequate system for operation and maintenance of the stormwater management
system will result in future compliance problems.
If any parts, requirements, or limitations contained in this permit are unacceptable, you have the right to request an
adjudicatory hearing upon written request within thirty (30) days following receipt of this permit. This request must
be in the form of a written petition, conforming to Chapter 150B of the North Carolina General Statutes, and filed
with the Office of Administrative Hearings, P.O. Drawer 27447, Raleigh, NC 27611-7447. Unless such demands
are made this permit shall be final and binding.
If you have any questions, or need additional information concerning this matter, please contact Scott Vinson, or
me at (910) 395-3900.
Sincerely,
Rick Sliver
Water Quality Regional Supervisor
RSS/:sav S:\WQS\STOP.MR'AT\PERMIT\000505.AUG
cc: Timothy Stewart, P.E.
Mitchell Parker, Onslow Count), Inspections
Scott Vinson
Wilmington Regional Office
Central Files
127 Cardinal Dr. Ext., Wilmington, North Carolina 28405 Telephone 910-395-3900 FAX 910-350-2004
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State Stormwater Management Systems
Permit No. SW8 000505
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
STATE•STORMWATER MANAGEMENT PERMIT
HIGH DENSITY DEVELOPMENT
In accordance with the provisions of Article 21 of Chapter 143, General Statutes of North Carolina as amended, and
other applicable Laws, Rules, and Regulations
PERMISSION IS HEREBY GRANTED TO
1st Wilmington Properties
Ashcroft at The Commons
Onslow County
FOR THE
construction, operation and maintenance of three wet detention ponds in compliance with the provisions of 15A
NCAC 21-1.1000 (hereafter referred to as the "stormwater rules') and the approved stormwater management plans
and specifications and other supporting data as attached and on file with and approved by the Division of Water
Quality and considered a part of this permit.
This permit shall be effective from the date of issuance until August 16, 2010 and shall be subject to the following
specified conditions and limitations:
I. DESIGN STANDARDS
1. This permit is effective only with respect to the nature and volume of stormwater described in the
application and other supporting data.
2. This stormwater system has been approved for the management of stormwater runoff as described on page
3 of this permit, the Proj ect Data Sheet. The subdivision is permitted for 117 lots, each allowed 2,400 square
feet of built -upon area.
3. Approved plans and specifications for this project are incorporated by reference and are enforceable parts
of the permit.
2
State Stormwater Management Systems
Permit No. SW8 000505
DIVISION OF WATER QUALITY
PROJECT DATA SHEET
Project Name:
Ashcroft at The Commons
Permit Number:
SW8 000505
Location:
Onslow County
Applicant:
Mr. Ernest D. Hackney, General Partner
Mailing Address:
1st Wilmington Properties
PO Box 3442
Wilmington, NC 28406
Application Date:
July 14, 2000
Name of Receiving Stream / Index #:
Northeast Creek / WOK02 1946-(0.5)
Classification of Water Body:
"SC NSW"
If Class SA, chloride sampling results:
n/a
Design Storm:
V
Pond #1 Pond 42
Pond 43
Pond Depth, feet:
6.0 6.0
6.0
Permanent Pool Elevation, FMSL:
42.50 43.50
44.00
Drainage Area, acres:
9.23 7.82
8.46
Total Impervious Surfaces, ftz:
194,387 122,643
154,678
117 lots at 2,400 ftz:
103,200 81,600
96,000
Roads/Parking, ftz
91,187 41,043
58,678
Offsite Area entering Ponds, ftz:
None, per Engineer
Required Surface Area, ftz:
10,457 6,473
8,175
Provided Surface Area, ftz:
11,100 11,100
11,100
Required Storage Volume, ft':
16,254 10,618
13,136
Provided Storage Volume, ft':
18,563 18,510
18,458
Temporary Storage Elevation, FMSL:
44.00 45.00
45.50
Controlling Orifice:
1.50" � 1.50" �
1.50" � pipe
3
State Stormwater Management Systems
Permit No. SW8 000505
]I. SCHEDULE OF COMPLIANCE
No homeowner/lot owner/developer shall fill in, alter, or pipe any drainage feature (such as swales) shown
on the approved plans as part of the stormwater management system without submitting a revision to the
permit and receiving approval from the Division.
2. The permittee is responsible for verifying that the proposed built -upon area for the entire lot, including
driveways and sidewalks, does not exceed the allowable built -upon area. Once the lot transfer is complete,
the built -upon area may not be revised without approval from the Division of Water Quality, and
responsibility for meeting the built -upon area limit is transferred to the individual property owner.
If an Architectural Review Committee (ARC) is required to review plans for compliance with the BUA
limit, the plans reviewed must include sidewalks and driveways. Any approvals given by the ARC do not
relieve the homeowner of the responsibility to maintain compliance with the permitted BUA limit.
4. The following items will require a modification to the permit:
a. Any revision to the approved plans, regardless of size.
b. Project name change.
C. Transfer of ownership.
d. Redesign or addition to the approved amount of built -upon area.
C. Further subdivision, acquisition, orsale of theproject area. Theprojectarea is defined as allproperty
owned by the permittee, for which Sedimentation and Erosion Control Plan approval was sought.
f. Filling in, altering, or piping of any vegetative conveyance shown on the approved plan.
5. The Director may determine that other revisions to the project should require a modification to the permit.
6. The Director may notify the permittee when the permitted site does not meet one or more of the minimum
requirements of the permit. Within the time frame specified in the notice, the permittee shall submit a written
time schedule to the Director for modifying the site to meet minimum requirements. The permittee shall
provide copies of revised plans and certification in writing to the Director that the changes -have been made.
The stormwater management system shall be constructed in it's entirety, vegetated and operational for its
intended use prior to the construction of any built -upon surface.
8. During constriction, erosion shall be kept to a minimum and any eroded areas of the system will be repaired
immediately.
9. Upon completion of construction, prior to issuance of a Certificate of Occupancy, and prior to operation of
this permitted facility, a certification must be received from an appropriate designer for the system installed.
certifying that the permitted facility has been installed in accordance with this permit, the approved plans
and specifications, and other supporting documentation. Any deviations from the approved plans and
specifications must be noted on the Certification.
10. Decorative spray fountains will not be allowed in the stormwater treatment system.
11. Iffthe stormwater system was used as an Erosion Control device, it must be restored to design condition prior
to operation as a stormwater treatment device, and prior to occupancy of the facility.
12. Unless specified elsewhere, permanent seeding requirements for the stormwater control must follow the
guidelines established in theNorth Carolina Erosion and Sediment Control Planning and Design Manual.
El
State Stormwater Management Systems
Permit No. SW8 000505
13. Prior to transfer of the permit, the pond must be inspected by DWQ personnel, and determined to be in
compliance with all permit conditions. Any items not in compliance must be repaired or replaced to design
condition prior to the transfer. Records of maintenance activities performed to date will be required.
14. The permittee shall at all times provide the operation and maintenance necessary to assure the permitted
stormwater system functions at optimum efficiency. The approved Operation and Maintenance Plan must
be followed in its entirety and maintenance must occur at the scheduled intervals including, but not limited
to:
a. Semiannual scheduled inspections (every 6 months).
b. Sediment removal.
C. Mowing and revegetation of side slopes.
d. Immediate repair of eroded areas.
C. Maintenance of side slopes in accordance with approved plans and specifications.
f. Debris removal and unclogging of outlet structure, orifice device and catch basins and piping.
g. Access to the outlet structure must be available at all times.
15. Records of maintenance activities must be kept and made available upon request to authorized personnel
of DWQ. The records will indicate the date, activity, name of person performing the work and what actions
were taken.
16. Prior to the sale of any lot, deed restrictions must be recorded which limit the built -upon area per lot to the
amount as shown on the Project Data Sheet, per Section I, Part 2. The recorded statements must follow the
form:
a. The maximum built -upon area per lot is 2,400 square feet. This allotted amount includes any built -
upon area constructed within the lot property boundaries, and that portion of the right-of-way
between the front lot line and the edge of the pavement. Built upon area includes, but is not limited
to, structures, asphalt, concrete, gravel, brick, stone, slate, coquina and parking areas, but does not
include raised, open wood decking, or the water surface of swimming pools."
b. "The covenants pertaining to stormwater regulations may not be changed or deleted without
concurrence of the State."
C. Alteration of the drainage as shown on the approved plan may not take place without the
concurrence of the State."
d. "Lots within CAMA's Area of Environmental Concern may be subject to a reduction in their
allowable built -upon area due to CAMA regulations."
e. "All runoff on the lot must drain into the permitted system. This may be accomplished through
providing roof drain gutters which drain to the street, grading the lot to drain toward the street, or
grading perimeter swales and directing them into the pond or street. Lots that naturally drain into the
system are not required to provide these measures."
17. A copy of the recorded deed restrictions must be submitted to the Division within 30 days of the date of
recording the plat, and prior to selling lots. The recorded copy must bear the signature of the Permittee, the
deed book number and page, and stamp/signature of the Register of Deeds.
State Stormwater Management Systems
Permit No. SW8 000505
18. This permit shall become voidable unless the facilities are constructed in accordance with the conditions of
this permit, the approved plans and specifications, and other supporting data.
19. A copy of the approved plans and specifications shall be maintained on file by the Permittee for a minimum
of ten years from the date of the completion of construction.
20. Built upon area includes, but is not limited to, structures, asphalt, concrete, gravel, brick, stone, slate,
coquina and parking areas, but does not include raised, open wood decking, or the water surface of
swimming pools.
I11. GENERAL CONDITIONS
This permit is not transferable. In the event there is a desire for the facilities to change ownership, or there
is a name change of the Permittee, a "Name/Ownership Change Form" must be submitted to the Division
of Water Quality accompanied by appropriate documentation from the parties involved, such as a copy of
the deed of trust. Other supporting materials, such as a signed Operation and Maintenance plan in the case
of engineered systems, will also be required. The project must be in good standing with DWQ. The approval
of this request will be considered on its merits and may or may not be approved.
2. Failure to abide by the conditions and limitations contained in this permit may subject the Permittee to
enforcement action by the Division of Water Quality, in accordance with North Carolina General Statute
143-215.6A to 143-215.6C.
3. The issuance of this permit does not preclude the Permittee from complying with any and all statutes, rules,
regulations, or ordinances which may be imposed by other government agencies (local, state, and federal)
which have jurisdiction.
4. In the event that the facilities fail to perform satisfactorily, including the creation of nuisance conditions,
the Permittee shall take immediate corrective action, including those as may be required by this Division,
such as the construction of additional or replacement stormwater management systems.
5. The permit may be modified, revoked and reissued or terminated for cause. The filing of a request for a
permit modification, revocation and reissuance or termination does not stay any permit condition.
6. Permittee grants permission to staff of the DWQ to access the property for the purposes of inspecting the
stormwater facilities during normal business hours.
The permittee shall notify the Division of any mailing address changes within 30 days.
Permit issued this the 16th day of August, 2000.
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
Kerr T. Stevens, Director
Division of Water Quality
By Authority of the Environmental Management Commission
Permit Number SW8 000505
State Stormwater Management Systems
Permit No. SW8 000505
Ashcroft at The Commons
Stormwater Permit No. SW8 000505
Onslow County
Designer's Certification
Page 1 of 2
1, , as a duly registered in
the State of North Carolina, having been authorized to observe (periodically/weekly/full time) the construction of
the project,
for (Project Owner) hereby state that, to the best of my abilities, due care
and diligence was used in the observation of the project construction such that the construction was observed to be
built within substantial compliance and intent of the approved plans and specifications.
The checklist of items on page 2 of this form are a part of this Certification.
Noted deviations from approved plans and specifications:
SEAL
Signature
Registration Number
Date
State Stormwater Management Systems
Permit No. SW8 000505
Certification Requirements:
Page 2 of 2
_I . The drainage area to the system contains approximately the permitted acreage.
_2. The drainage area to the system contains no more than the permitted amount of built -upon area.
_3. All the built -upon area associated with the project is graded such that the runoff drains to the system.
_4. The outlet/bypass structure elevations are per the approved plan.
5. The outlet structure is located per the approved plans.
6. Trash rack is provided on the outlet1bypass structure.
All slopes are grassed with permanent vegetation.
8. Vegetated slopes are no steeper than 3:1.
_9. The inlets are located per the approved plans and do not cause short-circuiting of the system.
10. The permitted amounts of surface area and/or volume have been provided.
_11. Required drawdown devices are correctly sized per the approved plans.
12. All required design depths are provided.
13. All required parts of the system are provided, such as a vegetated shelf, a forebay, and the vegetated filter.
14. The overall dimensions of the system, as shown on the approved plans, are provided.
cc: NCDENR-DWQ Regional Office
Mitchell Parker, Onslow County Building Inspector
DETENTION POND ANALYSIS
FILE NAME: S:\WQS\POND\000505.WK1
PROJECT #: SW8 000505 Pond #1
PROJECT NAME: Ashcroft at the Commons
REVIEWER: sav
DATE: 16-Aug-2000
Receiving Stream: Northeast Creek Class: SC N$W Chlorides: _
Drainage Basin: White Oak Index No. WOK02 19-6-(0.5)
Site Area 29.03 acres
Drainage Area 402Q58.80' square feet needs to be verified
Area in Acres 9.23 acres
IMPERVIOUS AREA Rational C-list beside
each item below in E15 to E20
On -Site Buildings & Drives 103200.00 square feet
On -Site Streets & Sidewalks 91187.00 square feet
square feet
square feet
square feet
square feet
TOTAL 194387:9 Cc= 0.10
% IMPERVIOUS 48.35%
Des. Depth
6.0 TSS: 90
SURFACE AREA CALCULATION
Rational ?
If Rational is used put a
SNDA
2.60%
"1" in box E26. If not, leave it blank.
Req. SA
10457
square feet
Prov. SA
111'00;; square feet
[From plan Contours]
VOLUME CALCULATION
Perm. Pool Volume= 34887
Req. Forebay Volume= 6977.4
Bottom
36.50
MSL
Provided Volume= 6900
Perm. Pool
42'50'
MSL
Percent= F7720W
Design Pool
44.00
MSL
Design SA
13650
square feet
inches
Des. Storm
Req. Volume
16254
cubic feet
Rv= r13113
Prov. Volume
18563,1
cubic feet
SA @ _
Elevation=
Avg. Head = 0.72 ft
Flow Q2, cfs 0.094 Area, in 3.32
Flow Q5, cfs 0.038 Area, in 1.33
No. of Orifices C 1 JDiameter, in. Area = 1.767 in'
Q, cfs = 0.050 Drawdown 38" days
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines.
DETENTION POND ANALYSIS
FILE NAME: S:\WQS\POND\000505.WK1
PROJECT* SW8 000505 Pond #2
PROJECT NAME: Ashcroft at the Commons
REVIEWER: sav
DATE: 16-Aug-2000
Receiving Stream: Northeast Creek Class: $SSW Chlorides:
Drainage Basin: White Oak Index No. WOK02 19-6-(0.5)
Site Area 29.03 acres
Drainage Area square feet needs to be verified
Area in Acres 7.82 acres
IMPERVIOUS AREA Rational C-list beside
each item below in E15 to E20
On -Site Buildings & Drives 81600.00 square feet
On -Site Streets & Sidewalks 41043.00 square feet
square feet
square feet
square feet
square feet
TOTAL 122643.00' Cc= 0.13
1:1� ,
% IMPERVIOUS 36.00%
Des. Depth
6.0 TSS: 90
SURFACE AREA CALCULATION
Rational ?
OIf Rational is used put a
SA/DA
1.90%
"1" in box E26. If not, leave it blank.
Req. SA
6473
square feet
Prov. SA
77
square feet
[From plan Contours]
VOLUME CALCULATION
Perm. Pool Volume= 34887
Req. Forebay Volume= 6977.4
Bottom
37.50
MSL
Provided Volume= 6900
Perm. Pool
F: 43.
MSIL
Percent= FFE20%i
Design Pool
45.00
MSIL
Design SA
13580
square feet
inches
IDes. Storm ij�,,!i�:,tOO
Req. Volume
i 106,18:icubic
feet
Rv= 0.37403405
Prov. Volume
Fr 3.18510
cubic feet
SA @
Elevation=
Avg. Head = 0.72 ft
Flow Q2, cfs 0.061 Area, in' 2.17
Flow Q5, cfs 0.025 Area, in 2 0.87
No. of Orifices 01 Diameter, in. 1.5Q Area 1.767 in 2
Q, cfs = 0.050 Drawdown days
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines.
DETENTION POND ANALYSIS
FILE NAME: S:\WQS\POND\000505.WK1
PROJECT* SW8 000505 Pond #3
PROJECT NAME: Ashcroft at the Commons
REVIEWER: sav
DATE: 16-Aug-2000
Receiving Stream: Northeast Creek Class: S_C_N,$W Chlorides:
Drainage Basin: White Oak Index No. WOK02 19-6-(0.5)
Site Area 29.03 acres
Drainage Area square feet needs to be verified
Area in Acres 8.46 acres
IMPERVIOUS AREA Rational C-list beside
each item below in E15 to E20
On -Site Buildings & Drives
On -Site Streets & Sidewalks
TOTAL
% IMPERVIOUS 41.97%
SURFACE AREA CALCULATION
96000.00 square feet
58678.00 square feet
square feet
square feet
square feet
square feet
Cc= 0.12
Des. Depth 6.0 TSS: 90
Rational ?
SA/DA 2.22%
Req. SA 8175 square feet
Prov. SA 111 square feet
Req. Volume 131.�cubic feet
Prov. Volume .,�1.8458 cubic feet
Avg. Head =
Flow Q2, cfs 0.076
Flow Q5, cfs 0.030
If Rational is used put a
"'I" in box E26. If not, leave it blank.
[From plan Contours]
Forebay Volume= 6977.4
ded Volume= 6900
Des. Storm
Rv=
SA @
0.72 ft
Area, in' 2.68
Area, in 2 1.07
No. of Orifices Diameter, in 1.50 Area = 1.767 in 2
Q, cfs = 0.050 Drawdown days
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines.
PARKER & ASSOCIATES, INC.
Consulting Engineers - Land Surveyors - Land Planners
306 New Bridge Street ♦ P.O. Box 976
Jacksonville, NC 28541-0976
(910) 455-2414 ♦ Fax:(910) 455-3441
Scott Vinson
NCDENR
Division of Water Quality
127 Cardinal Drive Extension
Wilmington, NC 28405-3845
Dear. Mr. Vinson,
Jul'
RE C E i V ED
JUL 14 2000
DWO
PAOJB
RE: Ashcrofl at the Commons
Stormwater Project No. SW8000505
Onslow County, North Carolina
This letter is in response to comments in your letter dated June 30, 2000 concerning the
above referenced project.
The Application and all three (3) Supplemental Forms have now been hand
initialed in the areas required. Please find enclosed the original forms that you had
returned to me to initial, and one copy of the forms for your use.
2. I have recalculated the required Temporary Storage Volume and Orifice Size as
you requested. I lowered the Temporary Storage height in all of the ponds to 1.5
feet instead of 3 feet as originally designed, and the Orifice Diameter changed to
1.5 inches instead of 2 inches as originally designed. These volumes and sizes are
reflected in the enclosed calculations and revised forms. Also the changes are
reflected on the enclosed two copies of the revised sheet 10 of 10 Stormwater
Pond Detail Sheet.
Along with the above enclosed revised plans and forms, please find enclosed two sets of
the revised specifications.
If you have any questions or need any additional information, please call.
Sincerely,
PARK R & AS O I TES, INC.
Timothy Swart, P.E.
xc: Mr. Deans Hackney w/enclosures
CIF (P) LAM
TMS/ees
c3: %TAmshms/ashcroB.Itr
ENVIRONMENTAL ENGINEERING ♦ STORM WATER MANAGEMENT ♦ WATER AND WASTEWATER SYSTEMS
DEVELOPMENT CONSULTING ♦ FEASIBILITY REPORTS ♦ COMPUTER AIDED DESIGN ♦ CONSTRUCTION PLANS
ASHCROFT AT THE COMMONS
Stormwater Narrative
Ashcroft at The Commons is being developed by I' Wilmington Properties. The
subdivision consists of H 7 Lots. The asphalt roads will be constructed with curb inlet catch
basins to collect stormwater and route it to the stormwater detention ponds prior to releasing the
stormwater runoff to the existing ditches. Due to the flatness of the site and the shallow existing
ditches, three stormwater ponds were necessary to serve this site. The ponds have been designed
with a maximum impervious area for each lot to be 2,400 square feet (this includes house,
driveway and sidewalk at house).
As shown on the typical Lot Grading Sketches #1 and #2 shown on Sheet 2 of 10, the
exterior lots shall be built up so that all of the runoff from all impervious areas shall flow to the
roads and then to the stormwater ponds.
The project drains into an unnamed tributary which flows into Northeast Creek which is
classified as SC -NSW.
For additional information, see the plans and specifications, and the rest of the permit
application package.
c:mydocumcnts\tm \ash.nu
TECHNICAL SPECIFICATIONS
FOR
STORMWATER DETENTION PONDS #1, #2 AND #3
TO SERVE
ASHCROFT AT THE COMMONS
-New-Hanover County, North Carolina
(l)nsloo
OWNER:
1ST Wilmington Properties
Wilmington, North Carolina
April 2000
Revised July 2000
PARKER & ASSOCIATES, INC.
Engineering - Surveying - Land Planning
P.O. Box 976
Jacksonville, North Carolina 28541.
N
�n
M.5
a�ECE1V'E0
JUL 14EM
Dwo
PROD ®--
Copyright ® 2000 by Parker & Associates, Inc.
tLl rights reserved. No part of this document may
bc. reproduced in any form or by any means without prioz
written permission. lase of this document, except by
those expressly authorized, is strictly prohibited.
w
PROJECT INFORMATION SHEET
OWNER:
1st Wilmington Properties
P.O. Box 3442
Wilmington, North Carolina 28406
Contact Person: Mr. Deans Hackney, General Partner
(910) 815-8012
ENGINEER:
Parker & Associates, Inc.
P. 0. Box 976
Jacksonville, NC 28541-0976
Contact Person: Timothy M. Stewart, P.E.
(910) 455-2414
ASHCROFT AT THE COMMONS
STORMWATER DETENTION PONDS #1, #2 and #3
GENERAL REQUIREMENT ................................... GR 1 - 4
1. Summary of Work
2. Field Engineering
3. Submittals
4. Testing Lab Services
5. Inspection/Certification
6. Guarantee of Work
SITE WORK ................................................. SW 1 - 5
1. Clearing and Grubbing
2. Excavation and Grading
3. Dewatering
4. Backfill
5. Piping System
6. Grassing
7. Erosion and Sediment Control Measures
DWQ STORMWATER APPLICATION AND SUPPLEMENT ................1 - 10
STORMWATER NARRATIVE.........................................1
ENGINEERING CALCULATIONS...............................ENG 1 -15
C: mydocumenls\specs�ash. cov
2.
GENERAL REQUIREMENTS
SUMMARY OF WORK
The CONTRACTOR for this.section shall furnish all materials,
supplies, equipment, labor, tools and all other incidentals
necessary to construct the Stormwater Detention Pond and
appurtenances, complete, and ready for use, as shown on the
plans and as enumerated herein.
Work necessary for the construction of the Stormwater Pond
includes but is not limited to clearing and grubbing,
dewatering, excavation, backfill, install piping system,
grassing, and erosion control as shown on the plans and as
outlined hereinafter.
FIELD ENGINEERING
A. OWNER will establish base lines for Project and a site
benchmark for use by the CONTRACTOR. OWNER will furnish
boundary surveys if required.
B. CONTRACTOR shall:
Develop and make all detail surveys and measurements
needed for construction including slope stakes,
batter boards, and all other working lines,
elevations and cut sheets.
2. Be solely responsible for all locations, dimensions`
and levels. No data other than written orders of
the ENGINEER shall justify departure from the
dimensions and levels required by the Drawings.
3. Safeguard all points, stakes, grade marks, monuments
and bench marks made or established on the Work, re-
establish same if disturbed and rectify all Work
improperly installed because of not maintaining, not
protecting or removing without authorization such
established points, stakes, marks and monuments.
4. When requested by ENGINEER, provide such facilities
as may be necessary for ENGINEER to check line and
grade points placed by CONTRACTOR. Where
applicable, CONTRACTOR shall do no excavation or
embankment work until cross -sectioning necessary for
determining pay quantities has been completed and
checked by ENGINEER.
GR-2
3. SUBMITTALS
The CONTRACTOR shall a minimum of three (3) copies of all
submittals of the various materials and products to the
ENGINEER for approval. Of these, one (1) copy will be
returned to the CONTRACTOR.
Each set of submittals shall include but not be limited to:
1. Drawings showing all dimensions units and locations of
all other accessory equipment, including a piping layout.
2. All technical information needed by the ENGINEER to
determine if the proposed equipment meets the plans and
specifications.
4. TESTING LAB SERVICES
A. General: Testing of materials, testing for moisture
content during placement and compaction .of fill
materials, and of compaction requirements for compliance
with technical requirements of the specifications shall
be performed by a testing laboratory.
B. Testing Services:
1. Test the CONTRACTOR'S proposed materials in the
laboratory and/or field for compliance with the
specifications.
2. Perform field moisture content and density tests to
assure that the specified compaction of backfill
materials has been obtained.
3. Report all test results to the ENGINEER and the
CONTRACTOR.
C. Authority and Duties of Testing Agency: Technicians
representing the testing laboratory shall inspect the
materials in the field and perform tests, and shall
report their findings to the ENGINEER and the CONTRACTOR.
When the materials furnished or work performed fails to
fulfill specification requirements, the technician will
direct the attention of the ENGINEER and. CONTRACTOR to
such failure.
The technician shall not act as foreman or perform other
duties for the CONTRACTOR. Work will be checked as it
progresses, but failure to detect any defective work
or materials shall not in any way prevent later rejection
when such defect is discovered, nor shall it obligate the
ENGINEER for acceptance. Technicians are not authorized
to revoke, alter, relax, enlarge, or release any
requirements of the specifications, nor to approve or
accept any portion of the work.
GR-3
5.
6.
D. Responsibilities and Duties of CONTRACTOR: The use of
testing services shall in no way relieve the CONTRACTOR
of his responsibility to furnish materials and
construction in full compliance with the drawings and
specifications.
To facilitate testing services, the CONTRACTOR shall:
Secure and deliver to the testing agency, without
cost, preliminary representative samples of the
materials he proposes to use and which are required
to be tested.
2. Furnish such casual labor as is necessary to obtain
and handle samples at the project or at other
sources of material.
Advise the testing agency sufficiently in advance of
operations to allow for completion of quality tests
and for the assignment of personnel.
INSPECTION/CERTIFICATION
Inspection by an ENGINEER is required in order to issue the
Certification of Construction as required by the Division of
Water Quality to assure the pond is built according to the
plans and specifications.
Parker & Associates, Inc., as ENGINEER, if authorzed by the
OWNER, will provide inspection throughout the performance of
this Contract. Inspections will be made periodically or on a
full time basis as the work progresses to insure compliance..
with these specifications and with the specification
requirements shown on the plans. When requested by the
ENGINEER, CONTRACTOR shall provide his services to insure to
the ENGINEER's satisfaction that all dimensions, lines and
grades are as designed. In order for the ENGINEER to
adequately inspect and approve this construction, testing
services shall be provided by an approved testing laboratory.
GUARANTEE OF WORK
A. Except as otherwise specified, all work .shall be
guaranteed by the CONTRACTOR and his sureties against
defects resulting from the use of faulty or inferior
materials, equipment, or workmanship for 12 months from
the date of final completion of the work as signified by
acknowledgement of receipt of Final Payment by the
CONTRACTOR.
If, within any guarantee period, repairs, or changes are
required in connection with guaranteed work, which, in
the opinion of the ENGINEER, are rendered necessary as
GR-4
the result of the use of materials, equipment, or
workmanship, which are inferior, defective, or no*. in
accordance with the terms of the CONTRACT, the CONTRACTOR
shall, promptly upon receipt of notice from the OWNER,
and without expense to the OWNER:
1. Place in satisfactory condition, in every
particular, all of such guaranteed work.
2. Correct all defects therein.
3. Make good all damage •to the site, which in the
opinion of the ENGINEER, is the result of the use of
materials, equipment, or workmanship which are
inferior, defective, or not in accordance with the
terms of the CONTRACT.
4. Make good any work or material, or the equipment and
contents of said building site, disturbed in
fulfilling any such guarantee.
C. If in fulfilling the requirements of the CONTRACT or of
any guarantee embraced therein or required thereby, the
CONTRACTOR disturbs any work guaranteed under another
CONTRACT, he shall restore such disturbed work to
condition satisfactory to the ENGINEER, and shall
guarantee such restored work to the same extent as it was
guaranteed under such other CONTRACT.
D. If the CONTRACTOR, after notice, fails to proceed
promptly to comply with the terms of the guarantee, the
OWNER may have the. defects corrected and the CONTRACTOR
and/or his Surety shall be liable for all expenses
incurred.
E. All special guarantees applicable to definite parts of
the work that may be stipulated in the specifications or
other papers forming a part of the CONTRACT shall be
subject to the terms of this section during the first
year of the life of such special guarantee.
SITE WORK
1. CLEARING AND GRUBBING
Clearing shall consist of the cutting, removal, and
satisfactory disposal of all trees, down timber, project
roots, stumps, lap wood rubbish, trash, and all other
objectionable material within the construction limits as
directed. Any specific trees or shrubs designated to be saved
by the OWNER shall be protected from injury during
construction.
Grubbing shall consist of the excavation, removal, and
disposal of all stumps, roots, logs, and other perishable
and objectionable material within the construction limits
as directed. ..
All clearing and grubbing shall be accomplished in such a
manner as not to injure or destroy any merchantable timber or
other property on land adjacent to the project site.
Before any burning of debris shall occur, contractor shall
contact owner and engineer for permission and location and
contractor will be required to secure ANY and ALL burning
permits required. All perishable material shall be burned in
such a manner as not to injure trees or shrubs outside the
project site or any tree or shrub designated to be saved. Any•
material that cannot be completely burned will be removed and
disposed of at an off -site location at the expense of the
contractor. If burning is not allowed, contractor is
responsible to remove all material from the site.
2. EXCAVATION AND GRADING
All grading and excavation shall be in accordance with typical
dimensions and cross -sections shown on the plans and
specifications contained herein.
During excavation all topsoil suitable for reuse shall be
stockpiled in an area designated by the OWNER. All soils
suitable for reuse as backfill material shall be stockpiled. in
a separate area designed by OWNER. All soils unsuitable for
reuse shall be stockpiled in a separate location as designated
by the OWNER. Services of the testing laboratory shall be
used to determine which soils are best suitable for reuse as
backfill.
In areas requiring back fill to construct the pond dikes, a
minimum of 12-inches of topsoil and subsoil stripping shall
occur prior to the commencement of backfill.
SV7-2
3.
DEWATERING
1. The CONTRACTOR shall provide and maintain adequate
dewatering equipment to remove and dispose of all surface
and ground water entering excavations, trenches, or other
parts of the work. Each excavation shall be kept dry
during subgrade preparation and continually thereafter
until the structure to be built,. or the pipe to be
installed therein is completed to the extent that no
damage from hydrostatic pressure, flotation., or other
cause will result.
A. The working areas on the site (exclusive of sediment
entrapment devices) shall be kept free of surface
water at all times. The CONTRACTOR shall install
drainage ditches and dikes and shall perform all
pumping and other work necessary to divert or remove
rainfall and all other accumulations of surface
water from the excavations and fill areas. The
diversion and removal, of surface eater shall be
performed in a manner that will prevent the
accumulation of water behind temporary structures or
at any other locations within the construction area
where it may be detrimental.
B. Water used for working or processing, resulting from
dewatering operations, or containing oils or
sediments that will reduce the quality of the water
sediments that will reduce the quality of the water
downstream of the point of discharge shall not be
directly discharged. Such waters shall be diverted
through a settling basin or filter before being
discharged.
C. The CONTRACTOR is responsible for the condition of
any pipe, conduit or channel which he may use for
drainage purposes and all such pipes, conduits or
channels shall be left clean and free of sediment.
2. The CONTRACTOR shall provide, install, and operate
sufficient trenches, sumps, pumps, hose, piping,
wellpoints, deep wells, etc., necessary to depress and
maintain the ground water level below the base of the
excavations during all stages of construction operations.
The ground water table shall be lowered in advance of
subgrade excavation and maintained two feet below the
lowest subgrade excavation made until the structure has
sufficient strength and weight to withstand horizontal
and vertical soil and water pressures from natural ground
water. The system must be operated on a 24-hour basis
and standby pumping facilities and personnel shall be
provided to maintain the continued effectiveness of the
system. If, in the opinion of the ENGINEER, the water
levels are not being lowered or maintained as required by
SW-3
these specification, the CONTRACTOR shall .install
additional or alternate dewatering devices as necessary,
at no additional cost to the OWNER.
4. BACKFILL
After completion of stripping the area to receive embankment
backfill and compaction, the CONTRACTOR shall place compacted
backfill to construct the dikes for the stormwater pond in
accordance with typical dimensions and cross -sections shown on
the plans and requirements contained in the specifications
herein.
Any soft areas of subgrade containing unsuitable, wet or
yielding material not readily capable of site compaction shall
be removed and replaced with compacted select borrow material.
Services of a testing laboratory shall be used to determine
which soils are suitable as select borrow material.
All fill shall be placed in horizontal loose lifts not
exceeding 8-inches in thickness and shall be mixed and spread
in a manner assuring uniform lift thickness after placing.
Each lift shall be compacted by not less than two (2) complete
coverages of the specified compactor. The compaction of the
complete area of the backfill shall have i minimum compacted
density of 95 percent as obtained by test procedures in ASTM
D 1557 (modified proctor). Services of a testing laboratory
shall be required to provide the CONTRACTOR with the required
compaction density results to insure compliance with the above
required compaction density.
No fill material shall be placed when free water is standing
on the surface of the area where the fill is to be placed. No
compaction of fill will be permitted with free water on any
portion of the fill to be compacted. No fill shall be placed
or compacted in a frozen condition or on top of frozen
material. Any fill containing organic materials or other
unacceptable material previously described shall be removed
and replaced with approved fill material prior to compaction.
Each lift of compacted fill shall be compacted by the
designated number of coverages of all portions of the
surface of each lift by a smooth -drum vibratory roller for
granular material having a static weight not less than 5,500
pounds, a sheepsfoot roller for cohesive material exerting a
pressure of 250 psi on the surface of the feet, or equivalent
equipment approved by the ENGINEER prior to commencement of
the work. One coverage is defined as the condition obtained
when subjected to the direct contact of the compactor. The
compactor shall be operated at a forward speed not exceeding
40 feet per minute.
SW-4
In some ares where soft soils are removed, it may be difficult
to properly compact the first lift or two on the base of the
undercut area. If the base is excessively wet, a working mat
of compacted crushed stone shall be placed prior to placement
and compaction of the fill.
5. PIPING SYSTEM
A. GENERAL
The piping system required shall be constructed and
installed as shown on the plans and as further described
herein. The stormwater pond piping system shall include
but not be limited to one 18-inch outlet pipe, one 18-
inch riser pipe, one trash rack, an anti -seep plate and
all appurtenances required for a complete installation.
B. PIPING
The piping included shall be to the diameters and lengths
shown on the plans. These pipes shall be fabricated of
corrugated aluminum made from alloys of ALCAD 3004 or
5052. They shall be helically corrugated Corlix as
manufactured by Kaiser Aluminum or an approved equal.
All welding required shall be done in the factory. The
units shall arrive to the site ready for installation.
Flanges shall be welded to the pipes for easy
connections in the field. The flanges shall be bolted
together using 3/8-inch stainless steel bolts, nuts and
washers and using 3/16-inch neoprene gaskets.
A trash rack shall be provided to the dimensions shown on
the plan. The trash rack shall include an aluminum
grate top with %-inch opening welded to the top.
An aluminum anti -seep plate shall be provided and
installed per the dimensions and locations shown on the
plans.
6. GRASSING
A. DIKES AND EMBANKMENTS
The CONTRACTOR after grading and shaping the dikes and
remaining areas as shown on the plans, shall furnish
labor, tools and equipment to till and seed any and all
areas, as outlined hereinbefore under site work.
The entire .area shall be given one application of
agricultural lime at the rate of 2,000 pounds per acre;
super phosphate at 500 pounds per acre; a 12-4-8 grade
fertilizer at the rate of 600 pounds per acre, all
harrowed to a point that it is thoroughly mixed with the
SW-5
soil. The Contractor shall then furnish and sow, Rebel
Fescue seed, at the rate of 100 pounds per acre mixed
with 25 pounds per acre of Bermuda.
A suitable cover of straw mulch shall be placed at a rate
of 1.5 to 2 tons per acre on the entire area following
the entire area to prevent the straw much from blowing
away and to assist in earlier germination. In the case
of extreme slopes, the straw mulch shall be stabilized by
the application of an asphalt or other approved binding
material.
The Contractor shall guarantee a full stand of grass over
the entire area. A stand of grass shall be considered
acceptable when cover is at least 95 percent.
7. EROSION AND SEDIMENT CONTROL MEASURERS
The erosion and sedimentation control measures shown on
the plans and contained in the Contract Documents
indicate the approximate locations of those measures on
the basis of the existing topography within the area or
on the basis of the predetermined need for any specific
area. Upon commencement'of the operations in those areas
where measures are proposed, the ENGINEER may make minor
adjustments in location. CONTRACTOR shall note and
observe all conditions as outlined in the Erosion and
Sedimentation Control Approval Letter.
It will be the CONTRACTOR'S responsibility to provide the
erosion and sediment control measures as shown on the
plans or as otherwise specified in the Contract Documents
or as directed by the Engineer. The CONTRACTOR is
cautioned that these facilities will be installed as
shown on the plans and/or as directed by the ENGINEER
during the construction process. Any citations,
penalties, or fines issued by the N.C. Department of
Environment and Natural Resources or any other agency
resulting from negligence of the CONTRACTOR shall hold
the ENGINEER or OWNER harmless from any resulting damages
or fines.
OFFICE USE ONLY -
Date Received
Fee Paid
Permit Number
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form maybe photocopied for use as an original
I. GENERAL INFORMATION
1. Applicants name (specify the name of the corporation, individual, etc. who owns the project):
1st Wilmington Properties
2. Print Owner/Signing Official's name and title (person legally responsible for facility and compliance):
3. Mailing Address for person listed in item 2 above:
P.O. Box 3442
City: Wilmington State: (AC Zip: 281i06
Telephone Number: ( 910 ) 7 6 3- 1 7 6 4
4. Project Name (subdivision, facility, or establishment name - should be consistent with project name on
plans, specifications, letters, operation and maintenance agreements, etc.):
Ashcroft at The'Commons -
5. Location of Project (street address):
Commons Drive South and Fairway Road
City: Jacksonville' County: Onslow-
6. Directions to project (from nearest major intersection):
On Western Boulevard Extension turn onto Gateway Drive h, then turn
onto Commons Drive South then turn right on West Fairway Road, across from,
Northside High School
7. Latitude: N 34°47' 20" Longitude: W77023' 31" of project
8. Contact person who can answer questions about the project:
Deans Hackne
IL PERMIT INFORMATION:
1. Specify whether project is (check one):
Telephone Number: ( 910 ) 7 6 3-17 6 4
X New
Renewal Modification
Donn SN't,1-101 Version 3.99 1 01-1
2. If this application is being submitted as the result of a renewal or modification to an existing permit, list the
existing permit number and its issue date (if known)
3. Specify the type of project (check one):
_Low Density X High Density _Redevelop _General Permit _Other
4. Additional Project Requirements (check applicable blanks):
_LAMA Major XSedimentation/Erosion Control _404/401 Permit NPDES Stormwater
Information on required state permits can be obtained by contacting the Customer Service Center at
1-877-623-6748.
III. PROJECT INFORMATION
1. In the space provided below, summarize how stormwater will be treated. Also attach a detailed narrative
(one to two pages) describing stormwater management for the project.
Subdivision will drain to three stormwater ponds
2. Stormwater runoff from this project drains to the
3. Total Project Area: 29.03 acres
White Oak
5. How many drainage areas does the project have? 3
River basin.
4. Project Built Upon Area: 37.3
6. Complete the following information for each drainage area. If there are more than two drainage areas in the
project, attach an additional sheet with the information for each area provided in the same format as below.
Pond 111 Pond #2
Pond #3
r .aYA(stt;"AMMRaa^...MY> #•$a ..>
Nam
u...« ..
....
Receiving Stream Name
Northeast Creek
-Northeast Creek -'Northeast
Creek
Receiving Stream Class
S
Drainage Area
Existing Impervious* Area
0
0
0
Proposed Imervious'Area
4.463 Acres
2.816 Acres
3.551 Acres
% Impervious* Area (total)
48%
36%
42%
ervious` Stiff ce Area
�s Diiinage .
arvl
. r
ge Area 3 ..
On -site Buildings &drives
103,200 SF
81 600 SF
96 000 SF
On -site Streetsgsidewalks
On.site-P-arking-
On-site Sidewalks -
Other on -site
Off -site
Total:19
3S7 F=4.463
=2
-
Impervious area is defined as the built upon area including, but not limited to, buildings, roads, parking areas,
sidewalks, gravel areas, etc. 43 L:> s [' 31 k4k � }
Form SNU-Illl Version 3.99 Page 2 of 4
s
/. How was the off -site impervious area listed above derived?
-V. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
the following italicized deed restrictions and protective covenants are required to be recorded for all
subdivisions, outparcels and future development prior to the sale of any lot. if lot sizes vary significantly, a
table listing each lot number, size and the allowable built -upon area for each lot must be provided as an
attachment.
1. The following covenants are intended to ensure ongoing compliance with state stormwater management Permit
number .S W S 600,Yos- as issued by the Division of Water Quality. These covenants may
not be changed or deleted without the consent of the State.
2. No more than 21400 square feet of any lot shall be covered by structures or impervious materials.
Impervious materials include asphalt, gravel, concrete, brick, stone, slate or similar material but do not include wood
decking or the water surface of swimming pools.
3. Swales shall not be filled in, piped, or altered except as necessary to provide driveway crossings.
4. Built -upon area in excess of the permitted amount requires a state stormwater management permit modification prior to
construction.
5. All permitted runoff from outparcels or future development shall be directed into the permitted stormwater control
system. These connections to the stormwater control system shall be performed in a manner that maintains the
integrity and performance of the system as permitted.
By your signature below, you certify that the recorded deed restrictions and protective covenants for this project
shall include all the applicable items required above, that the covenants will be binding on all parties and -.
persons claiming under them, that they will run with the land, that the required covenants cannot be changed or
deleted without concurrence from the State, and that they will be recorded prior to the sale of any lot.
V. SUPPLEMENT FORMS
The applicable state stormwater management permit supplement form(s) listed below must be submitted for
each BMP specified for this project. Contact the Stormwater and General Permits Unit at (919) 733-5083 for the
status and availability of these forms.
Form SWU-102
Wet Detention Basin Supplement
Form SWU-103
Infiltration Basin Supplement
Form SWU-104
Low Density Supplement
Form SWU-105
Curb Outlet System Supplement
Form SWU-106
Off -Site System Supplement
Form SWU-107
Underground Infiltration Trench Supplement
Form SWU-108
Neuse River Basin Supplement
Form SWU-109
Innovative Best Management Practice Supplement
Fuxin SWt:-Illl Version 3.99 Pa@e 3 of 4
VI. SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Water Quality (DWQ).
A complete package includes all of the items listed below. The complete application package should be
submitted to the appropriate DWQ Regional Office.
1. Please indicate that you have provided the following required information by initialing in the space
provided next to each item.
Initials
• Original and one copy of the Stormwater Management Permit Application Form _ --J m 5
• One copy of the applicable Supplement Form(s) for each BMP _ 11VAS
• Permit application processing fee of $420 (payable to NCDENR) I iti 1
• Detailed narrative description of stormwater treatment/management TtM j
• Two copies of plans and specifications, including: 1M�
- Development/Project name
- Engineer and firm
-Legend
- North arrow
- Scale
- Revision number & date
- Mean high water line
- Dimensioned property/project boundary
- Location map with named streets or NCSR numbers
- Original contours, proposed contours, spot elevations, finished floor elevations
- Details of roads, drainage features, collection systems, and stormwater control measures
- Wetlands delineated, or a note on plans that none exist
- Existing drainage (including off -site), drainage easements, pipe sizes, runoff calculations
- Drainage areas delineated
- Vegetated buffers (where required)
VII. AGENT AUTHORIZATION
If you wish to designate authority to another individual or firm,so that they may provide information on your
behalf, please complete this section. '
Designated agent (individual or firm): Parker & Associates, Inca
Mailing Address: P.O. Box 976,
City: Jacksonville State: NC Zip: 28540
Phone:( 910 ) 455- 2414 Fax: ( 910 1 455-3441
VIII. APPLICANT'S CERTIFICATION
I, (print or type name of person listed in General Information, item 2) Ernes Deans Hackney
certify that the information included on this permit application form is, to the best of my knowledge, correct and
that the project will be constructed in conformance with the approved plans, that the required deed restrictions
and protective covenants will be recorded, and that the proposed project complies with the requirements of 15A
NCAC 2H I nnn
Date: �Z_6 -oa
Form S%v1;-101 Version I(A) Pale 4 of 4
Pennit No. G�c� O60 6 r
(to be provided b7 DWQ)
State of North Carolina
Department of Envirorunent and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWQ Stormwater Management Plan Review:
A. complete stormwater management plan submittal includes an application form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: Ashnrnft at The Commons
Contact Person: neant Harkney Phone Number: ( 910) 763 1764
For projects with multiple basins, specify which basin this worksheet applies to: 1
elevations
Basin Bottom Elevation 36.5 ft.
Permanent Pool Elevation 42.5 ft.
Temporary Pool Elevation 44.0, ft,
areas
Permanent Pool Surface Area i i I oo sq. ft.
Drainage Area
Impervious Area
volumes
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
Other parameters
SA/DAI
Diameter of Orifice
9.23 ac.
(floor of the basin)
(elevation of the orifice)
(elevation of the discharge structure overflow)
(wuter surface area at the orifice elevation)
(on -site and off -site drainage to the basin)
(on -site and off -site drainage to the basin)
34 - 887 cu. ft. (combined volume of main basin and forebay)
18,365 cu. ft. (volume detained above the permanent pool)
6,900 cu. ft. (approximately 20% of total volume)
2 Ty (surface area to drainage area ratio from DWQ table)
1 .5 in. (2 to 5 day temporan, pool draw -down required)
Design Rainfall 1
Design TSS Removal z 90
in.
% (minimum 85% required)
Form SWU-102 Rey V)Q Page I of 4
Footnotes:
When using the Division SAIDA tables, the correct SAIDA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90%c TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
.,
IMS a.
The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
TM4 b.
The forebay volume is approximately equal to 20% of the basin volume.
�Ml c.
The temporary pool controls runoff from the design storm event.
TMi d.
The temporary pool draws down in 2 to 5 days.
IIAti N / n e.
If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
_6A f.
The basin length to width ratio is greater than 3:1.
(M� g.
The basin side slopes above the permanent pool are no steeper than 3:1.
TMS h.
A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).'
Tt^� i.
Vegetative cover above the permanent pool elevation is specified.
Thi j.
A trash rack or similar device is provided for both the overflow and orifice.
k.
A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
1.
If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
�My * m.
A mechanism is specified which will drain the basin for maintenance or an emergency.
*k: will be
recroded at a later date
*m: If pond
ever has to be drained, a pump will be used.
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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) 0 does d does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does Q does not incorporate pretreatment other than a forebay.
Form S1XU-]()2 kev 3.99 Pope 2 of 3
Maintenance activities shall be performed as follows:
I. After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs
within 2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet detention basin or stream, etc.).
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 4.5 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4.5 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(M in the blanks)
Permanent Pool Elevation 42 ti
Sediment Re oval El.Q,Sj 75
Sediment Removal Elevation a a n 75'h
Bottom Ele ation 3 % ------------------------
-------------
Bottom Elevation s 25%
FOREBAY MAIN POND
5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
Donn SWU• 102 Rev 3.99
Page 3 of 4
All components of the wet detention basin system shall be maintained in food working order.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
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. A
Print name:
v v
Title: s-
Address:
l�o. -ix
Date: Z/'G - 00
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 C2rxwz' , , a Notary Public for the State of
County of A2r / 122 ' 1' ti' do hereby certify that Ezi sI O
personally appeared before me this day of
ZJO ° > and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
= z i
=mt ° s
YgNO `✓ EP GO\\\��
SEAL
My commission expires '�°`
, SWU-102 Rev 3.99 Page 4 of 4
P e n n i t No. _3LJ�'' 0to ,5b7
(robe provided b.N DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWO Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention -basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: Ashcroft at'The Commons
Contact Person: Deans Hackney Phone Number: L910
For projects with multiple basins, specify which basin this worksheet applies to:
2
763 174I
elevations
Basin Bottom Elevation 37.5 ft. (floor of the basin)
Permanent Pool Elevation 43.5 ft. (elevation of the orifice)
Temporary Pool Elevation 45.0 ft. (elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area 11,100 sq. ft. (water surface area at the orifice elevation)
Drainage Area 7.82 ac. (on -site and off -site drainage to the basin)
Impervious Area 2.816 ac. (on -site and off -site drainage to the basin)
volumes
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
Other parameters
SA/DA t
Diameter of Orifice
Design Rainfall
Design TSS Removal 2
34,887 cu. ft. (combined volume of main basin and forebay)
1 8, 365 cu. ft. (volume detained above the permanent pool)
6,900 cu. ft. (approximately 20% of total volume)
2.1% (surface area to drainage area ratio from Dli'Q table)
1 .5 in. (2 to 5 day ternporary pool draw -down required
1 in.
90 % (rnininuun 85r10 required)
i........ III" • �. ') „.... � Dui II...,.. I ICI _I
Footnotes:
When using the Division SA/DA tables, the correct.SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
'- In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detentionbasin is designed to provide
90% TSS removal. The NCDENR BMP manual.provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
Hai a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
(r+i b. The forebay volume is approximately equal to 20% of the basin volume.
TMi c. The temporary pool controls runoff from the design storm event.
TMi d. The temporary pool draws down in 2 to 5 days.
'(lal NLA e. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
1M1 f. The basin length to width ratio is greater than 3:1.
�P^4 g. The basin side slopes above the permanent pool are no steeper than 3:1.
Tf^i h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
i. Vegetative cover above the permanent pool elevation is specified.
j. A trash rack or similar device is provided for both the overflow and orifice.
TMf k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
TM1 1. If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
TNrti m. A mechanism is specified which will drain the basin for maintenance or an emergency.
*k: Will be recorded at a later time
*m: If pond ever needs to bewdra.ined, a pump will be used
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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) 0 does *does not incorporate a vegetated filter at the outlet.
']'his system (check on(!) 0 does (%floes not incorporate pretreatment other than a forebay.
POrin SIXI- oI key _I u() I`i,.,,. , n;'..
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs
within 2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet detention basin or stream, etc.).
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 4.5 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4. 5 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 4 3 : 5
_.
Sediment Re oval El. 3g p _____________175
_ Sediment Removal Elevation3 `_. Q_ 75%
Bottom Ele •anon 37 • 5 "�--------------------------------------------- -------
Bottom Elevation 37. 5 259c
FOREBAY MAIN POND
Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
Form SWU-102 Rev 399 Pave 3 of 4
7 All rnmponcMl 01 the wcl d-"; !Rion hasin <Iem .hall he m:oni:tinctl in L'ood workin, or r.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed abo%e. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Printname: Ernest Deans Hackney
General Partner
P.O. Box 3442, Wilmington, NC 28406
(910) 815 8012
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.
a Notary Public for the State of✓�-r/--.i.,
County of k ✓. ; l4 r1.r .Ln, e do hereby certify that '5L 7-)c 4 Ar'
personally appeared before me this '"?6' day of ` , ZL)O 6, and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
i
O,'�CARo p✓,
......
ate;'• NOT
Z' G -P
m` -C rn zz
NX
/i/OUN'T ( ,\�0
llq ttlttttt\Ct� SEAL
My commission expires
Form S W 0-102 Rev i.99 Pine 4 of 4
i
Pennit No. 4kJe O[iU )Us
(to he provided by DIt Q)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention .basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: Ashcroft at The Commons
Contact Person: Deans Hackney Phone Number: (910 ) 763 1741
For projects with multiple basins, specify which basin this worksheet applies to: 3
elevations
Basin Bottom Elevation
38.0
ft.
(floor of the basin)
Permanent Pool Elevation
44.0
ft.
(elevation of the orifice)
Temporary Pool Elevation
45.5
ft.
(elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area
11,100
sq. ft.
(water surface area at the orifice elevation)
Drainage Area
8.46
ac.
(on -site and off -site drainage to the basin)
Impervious Area
3,551
ae.
(on -site and off -site drainage to the basin)
volumes
Permanent Pool Volume 34,887 cu. ft. (combined volume of main basin and foreba))
Temporary Pool Volume 18,365 cu. ft. (volume detained above the permanent pool)
Forebay Volume 6,900 cu. ft. (approximately 20% of total volume)
Outer parameters
SA/DAI ?_4% (surface area to drainage area ratio from DWQ table)
Diameter of Orifice 1 •5 in. (2 to 5 da.v temporan• pool draw -down required)
Design Rainfall 1 in.
Design TSS Removal 2 90 no (minimum 8517o required)
Footnotes:
When using the Division SA/DA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
'- In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85 is TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
7MS a.
1t�.S b.
fR C.
%S d.
TMi N/A e.
�AS f
The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
The forebay volume is approximately equal to 20% of the basin volume.
The temporary pool controls runoff from.the design storm event.
The temporary pool draws down in 2 to 5 days.
If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
The basin length to width ratio is greater than 3:1.
The basin side slopes above the permanent pool are no steeper than 3:1.
A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
TM� 1. If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
h) m. A mechanism is specified which will drain the basin for maintenance or an emergency..
*k: Will be recorded at a later time
*m: If pond ever has to be drained, a pump will be used
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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) 0 does 0 does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does 0 does not incorporatepretreatment other than a forehay.
. v�m, �'.\�I �-Ili' i'•,� ,r.:
Maintenance activities shall be performed as follows:
I. After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs
within 2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet detention basin or stream, etc.).
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 4. 9 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4. 5 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks) �rC� "'r• .
Permanent Pool Elevation
Sediment Re oval El. 39 _ 5 75 '
39. 5 ,. ,:
-------------- -- Sediment Removal Elevation 75%
Bottom Ele ation 3 B . 0 qc--------------------------------------------- ------
Bottom Elevation 38 . 0 25%
FOREBAY MAIN POND
5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
Form SwU-10'_' Rev 3.99 Page 3 ol'4
All components of life wet detention basin systcm Shall he maintained in ,_oval w li.ina order.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
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.
Print
General Par
'Flo ' 1 .. .. .. �.
t)ate: Z-rl;z& -Ott
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, �/'�7 �e S_ %��a ��i�� a Notary Public for the State of
County of firs/a 1 do hereby certify that
personally appeared before me this 26 day of 7000 , and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
M:W
My commission expires �" -'2 � - Z O0/
Form SNVG-102 Rev 3.99 Pa�c 4 of 4
ASHCROFT AT TIM COMMONS
Stormwater Narrative
Ashcroft at The Commons is being developed by 1" Wilmington Properties. The
subdivision consists of 117 Lots. The asphalt roads will be constructed with curb inlet catch
basins to collect stormwater and route it to the stormwater detention ponds prior to releasing the
stormwater runoff to the existing ditches. Due to the flatness of the site and the shallow existing
ditches, three stormwater ponds were necessary to serve this site. The ponds have been designed
with a maximum impervious area for each lot to be 2,400 square feet (this includes house,
driveway and sidewalk at house).
As shown on the typical Lot Grading Sketches #1 and 92 shown on Sheet 2 of 10, the
exterior lots shall be built up so that all of the runoff from all impervious areas shall flow to the
roads and then to the stormwater ponds.
The project drains into an unnamed tributary which flows into Northeast Creek which is
classified as SC -NSW.
For additional information, see the plans and specifications, and the rest of the permit
application package.
c:nrydncumentsUms�wli. nar
ASHCROFT AT THE COMMONS
ONSLOW COUNTY, NORTH CAROLINA
STORMWATER DETENTION POND #1
ENGINEERING CALCULATIONS
1. AREA
Total Area Draining to Pond from Roads and Lots
(including pond area)...................................................................9.23 Acres
Impervious Area:
Roads and Sidewalks................................................................91,187 SF = 2.093 Acres
Houses, driveways and walks ..... 43 Lots x 2400 SF/Lot (Max)=103,200 SF = 2.369 Acres
Total = 194,387 SF=4.463Acres
Percent Impervious = Impervious = 4.463 = 48 %
Total 9.23
2. PERMANENT POND SURFACE AREA
From Chart 4 -Appendix E from D.E.M. Report 87-05, for 50% impervious,6.0 basin
depth without Vegetative Filter (90% TSS Removal) Yields SA/DA = 2.7%
9.23 acres x 2.7% = 0.2492 acres or 10,856 SF surface area required
Top of permanent pond elevation is 42.5
Area at 42.5 elevation = 11.100 SF provided
11,100 SF provided > 10,856 SF required
3. TEMPORARY DETENTION STORAGE VOLUME
Retain 1" of runoff from impervious area draining to pond
Total Area = 4.463 Acres
Total Runoff = 4.463 AcAn.
Find Temporary Storage Volume
4.463 AcAn. x 3,630 C.F. = 16,201 C.F. required
AcAn.
ENG-2
4. TEMPORARY DETENTION STORAGE VOLUME
Use 1.5 Ft. Temporary Pool
Area at 42.5 elevation (permanent pond) = 11,100 SF
Area at 44.0 elevation (temporary pond) = 13,386 SF
Average Area = 12,243 SF
Storage Vol.= 12,243 SF x 1.5 Height = 18,365 C.F. provided
18,365 C.F. provided > 16,201 C.F. required
5. RELIEVE TEMPORARY STORAGE VOLUME IN 2 TO 5 DAYS
Q = Cd A 2gh (orifice equation)
Q = 16,201 C.F. = 2 days = 0.0938 CFS
Q = 16,201 C.F. + 5 days = 0.0375 CFS
Cd = 0.60
g = 32.2 ft/sec
h = 0.75 average height
For 2 Day Release
Solve For A = Q =
CD 2gh
Solve for Orifice Diameter, D
A = 0.0225 SF = n R'
R = 0.085 ft. = 1.06 inch
D=2.Oinch
For 5 Day Release
0.0938
(0.6) 2(32.2)(0.75)
= 0.0225 S.F.
Solve For A = Q = 0.0375 = 0.0090 S.F.
CD 2gh (0.6) 2(32.2)(0.75)
ENG-3
Solve for Orifice Diameter, D
A = 0.0090 SF = TT R2
R = 0.054 ft. = 0.642 inch
D = 1.3 inch
Use 1.5 inch diameter orifice
6. SIZE INLET RISER PIPE AND OUTLET PIPES TO HANDLE 10 YR. 1 HR.
STORM
A. Storm Flow
Q = CiA
A = 9.23 acres
C = 0.6
i = 2.88 in./hr. - 10 year, 1 hr. storm
Q = 0.6 (2.88) 9.23 = 15.9 cfs
7. Outlet Weir
Water height before topping spillway = 46.0 - 45.5 = 0.5
Q = Cd A 2gh(odfice equation)
Cd = 0.6 (typical valve)
H = 0.5
A=9SF
g = 32.2
Q = 0.6(9) 2(32.2)0.5 = 30.6 C.F.S.
Q = 30.6 CFS -Will accept 10 Yr. 1 Hr. Flow
a. Check Gravity Flow
ENG-4
24" Pipe Installed at 0.50%
Use Manning's Equation
Q= 1.49 A R 2/3 S 1/2
n
For 24" Pipe, Q = 16.0 CFS, which is equal to the 10 year - 1 hour flow
Use 24" Pipe
9. DESIGN TO HANDLE 100-YR. 1 HR. STORM THROUGH RISER, OUTLET
PIPE AND SPILLWAY PRIOR TO TOPPING POND
Q = CiA
Composite C = 0.6
iloo = 4.15 irtlhr for 100 year, 1 hr storm
A = 9.23 Ac.
Q = 0.6(4.15)(9.23) = 23.0 CFS
A. Outlet Weir
As Previously calculated, outlet weir can handle 30.6 CFS which is greater
than 100 yr. flow
B. Outlet Pipe
As calculated previously, outlet pipe will carry 16.0 CFS flowing full which
is less than the 100 yr. flow, therefore, emergency spillway is required.
C. Emergency Spillway
ENG-5
Use Manning's Equation
0.50 ft. deep Trapezoidal Swale with 10 ft. wide bottom and 10:1 side
slopes @ 3.3% Longitudal slope
Use n=0.06 for Grassed Swale
Q=17.5 CFS
Total capacity of Spillway + Outlet Pipes=17.5 + 16.0=33.5 CFS
33.5 CFS > 23.0 CFS
Therefore will handle 100-yr. 1 hr. storm
10. FOREBAY VOLUME
Forebay Volume shall contain approximately 20% of the total permanent
pond volume.
Volume of Permanent Pool 34,887 CF
Forebay Volume Required
34,887 CF X 20% = 6,977 CF
Total Volume Provided = 6,900 CF
uwpdocsVms�ashpond 1.cal
ASHCROFT AT THE COMMONS
ONSLOW COUNTY, NORTH CAROLINA
STORMWATER DETENTION POND #2
ENGINEERING CALCULATIONS
Total Area Draining to Pond from Roads and lots
(including pond area)...................................................................7.82 Acres
Impervious Area:
Roads and Sidewalks................................................................41,043 SF = 0.942 Acres
Houses, driveways and walks ..... 34 Lots x 2400 SF/Lot (Max) = 81,600 SF = 1.873 Acres
Total = 122,643 = 2.816 Acres
Percent Impervious = Impervious = 2.816 = 36 %
Total 7.82
2. PERMANENT POND SURFACE AREA
From Chart4 - Appendix E from D. E.M. Report87-05, for 40% impervious,6.0 basin
depth without Vegetative Filter (90% TSS Removal) Yields SA/DA = 2.1 %
7.82 acres x 2.1 % = 0.1642 acres or 7,153 SF surface area required
Top of permanent pond elevation is 43.5
Area at 43.5 elevation = 11,100 SF provided
11,100 SF provided > 7,153 SF required
3. TEMPORARY DETENTION STORAGE VOLUME
Retain 1" of runoff from impervious area draining to pond
Total Area = 2.816 Acres
Total Runoff = 2.816 Ac.-In.
Find Temporary Storage Volume
2.816 Ac.-In. x 3,630 C.F. = 10,222 C.F. required
Ac.-In.
4. TEMPORARY DETENTION STORAGE VOLUME
Use 1.5 Ft. Temporary Pool
Area at 43.5 elevation (permanent pond) = 11,100 SF
Area at 45.0 elevation (temporary pond) = 13,386 SF
Average Area = 12,243 SF
Storage Vol.= 12,243 SF x 1.5 Height = 18,365 C.F. provided
18,365 C.F. provided > 10,222 C.F. required
5. RELIEVE TEMPORARY STORAGE VOLUME IN 2 TO 5 DAYS
Q = Cd A 2gh (orifice equation)
Q = 10,222 C.F. = 2 days = 0.0592 CFS
Q = 10,222 C.F. = 5 days = 0.0237 CFS
Cd = 0.60
g = 32.2 ft/sec
In = 0.75 average height
For 2 Day Release
Solve For A = Q = 0.0592 = 0.0142 S.F.
CD 2gh (0.6) 2(32.2)(0.75)
Solve for Orifice Diameter, D
A=0.0142SF=TT RI
R = 0.0672 ft. = 0.81 inch
D = 1.6 inch
For 5 Day Release
Solve For A = Q =
CD 2gh
0.0237
(0.6) 2(32.2)(0.75)
= 0.0057 S.F.
ENG-2
ENG-3
Solve for Orifice Diameter, D
A = 0.0057 SF = TT RI
R = 0.043 ft. = 0.51 inch
D = 1.0 inch
Use 1.5 inch diameter orifice
6. SIZE INLET RISER PIPE AND OUTLET PIPES TO HANDLE 10 YR. 1 HR.
STORM
A. Storm Flow
Q = CiA
A = 7.82 acres
C = 0.6
i = 2.88 in./hr for 10 year 1 hr. storm
Q = 0.6 (2.86) 7.82 = 13.5 cfs;
7. Outlet Weir
Water height before topping spillway = 47.0 - 46.5 = 0.5
Q = Cd A 2gh(orifice equation)
Cd = 0.6 (typical valve)
H=0.5
A=9SF
g = 32.2
Q = 0.6(9) 2(32.2)0.5 = 30.6 C.F.S.
Q = 30.6 CFS - Will accept 10 Yr. 1 Hr. Flow
8. Check Gravity Flow
ENG-4
24" Pipe Installed at 0.35%
Use Manning's Equation
Q= 1.49 A R 2/3 S 1/2
n
For 24" Pipe, Q = 13.5 CFS, which is equal to the 10 year - 1 hour flow
Use 24" Pipe
9. DESIGN TO HANDLE 100-YR. 1 HR. STORM THROUGH RISER, OUTLET
PIPE AND SPILLWAY PRIOR TO TOPPING POND
Q = CiA
Composite C = 0.8
i100 = 4.15 inlhr for 100 year, 1 hr storm
Q = 0.6(4.15)(7.82) = 19.5 CFS
A. Outlet Weir
As Previously calculated, outlet weir can handle 30.6 CFS which is greater
than 100 yr. flow
B. Outlet Pipe
As calculated previously, outlet pipe will carry 13.5 CFS flowing full which
is less than the 100 yr. flow, therefore, emergency spillway is required.
10
ENG-5
C. Emergency Spillway
Use Manning's Equation
0.50 ft. deep Trapezoidal Swale with 10 ft. wide bottom and 10:1 side
slopes @ 3.3% Longitudal slope
Use n=0.06 for Grassed Swale
Q=17.5 CFS
Total capacity of Spillway + Outlet Pipes=17.5 + 13.5=31.0 CFS
31.0 CFS > 19.5 CFS
Therefore will handle 100-yr. 1 hr. storm
FOREBAY VOLUME
Forebay Volume shall contain approximately 20% of the total permanent
pond volume.
Volume of Permanent Pool 34,887 CF
Forebay Volume Required
34,887 CF X 20% = 6,977 CF
Total Volume Provided = 6,900 CF
c wpdocsfts�ashcroft.cal
ASHCROFT AT THE COMMONS
ONSLOW COUNTY, NORTH CAROLINA
STORMWATER DETENTION POND #3
ENGINEERING CALCULATIONS
1. AREA
Total Area Draining to Pond from Roads and lots
(including pond area)...................................................................8.46 Acres
Impervious Area:
Roads and Sidewalks................................................................58,678 SF = 1.347 Acres
Houses, driveways and walks ..... 40 Lots x 2400 SF/Lot (Max) = 96,000 SF = 2.204 Acres
Total=154,678 SF = 3.551 Acres
Percent Impervious = Impervious = 3.551 = 42 %
Total 8.46
2. PERMANENT POND SURFACE AREA
From Chart 4 - Appendix E from D. E.M. Report 87-05, for 45% impervious,6.0 basin
depth without Vegetative Filter (90% TSS Removal) Yields SA/DA = 2.4%
8.46 acres x 2.4% = 0.2030 acres or 8,844 SF surface area required
Top of permanent pond elevation is 44.0
Area at 44.0 elevation = 11,100 SF provided
11,100 SF provided > 8,844 SF required
3. TEMPORARY DETENTION STORAGE VOLUME
Retain 1" of runoff from impervious area draining to pond
Total Area = 3.551 Acres
Total Runoff = 3.551 Ac.-In.
Find Temporary Storage Volume
3.551 Ac.-In. x 3,630 C.F. = 12,890 C.F. required
Ac.-In.
El
ENG-2
TEMPORARY DETENTION STORAGE VOLUME
Use 1.5 Ft. Temporary Pool
Area at 44.0 elevation (permanent pond) = 11,100 SF
Area at 45.5 elevation (temporary pond) = 13,386 SF
Average Area = 12.243 SF
Storage Vol.= 12,243 SF x 1.5 Height = 18,365 C.F. provided
18,365 C.F. provided > 12,890 C.F. required
5. RELIEVE TEMPORARY STORAGE. VOLUME IN 2 TO 5 DAYS
Q = Cd A 2gh (orifice equation)
Q = 12,890 C.F. _ 2 days = 0.0746 CFS
Q = 12,890 C.F. = 5 days = 0.0298 CFS
Cd = 0.60
g = 32.2 ft/sec
h = 0.75 average height
For 2 Day Release
Solve For A = Q = 0.0746 = 0.0179 S.F.
CD 2gh (0.6) 2(32.2)(0.75)
Solve for Orifice Diameter, D
A=0.0179SF=TTR'
R = 0.076 ft. = 0.91 inch
D = 1.8 inch
For 5 Day Release
Solve For A = Q = 0.0298 = 0.0071 S.F.
CD 2gh (0.6) 2(32.2)(0.75)
ENG-3
Solve for Orifice Diameter, D
A=0.0071 SF=nRZ
R = 0.0477 ft. = 0.572 inch
D = 1.1 inch
Use 1.5 inch diameter orifice
6. SIZE INLET RISER PIPE AND OUTLET PIPES TO HANDLE 10 YR. 1 HR.
STORM
A. Storm Flow
Q = CiA
A = 8.46 acres
C = 0.6
i = 2.88 inAhr. storm
Q = 0.6 (2.88) 8.46 = 14.6 cfs
7. Outlet Weir
Water height before topping spillway = 46.5 - 47.0 = 0.5
Q = Cd A 2gh(orifice equation)
Cd = 0.6 (typical valve)
H = 0.5
A =9SF
g = 32.2
Q = 0.6(9) 2(32.2)0.5 = 30.6 C.F.S.
Q = 30.6 CFS - Will accept 10 Yr. 1 Hr. Flow
B. Check Gravity Flow
24" Pipe Installed at 0.06%
ENG-4
Use Manning's Equation
Q= 1.49 A R 2/3 S 1/2
n
For 24" Pipe, Q = 17.5 CFS, which is equal to the 10 year - 1 hour flow
Use 24" Pipe
9. DESIGN TO HANDLE 100-YR, 1 HR. STORM THROUGH RISER, OUTLET
PIPE AND SPILLWAY PRIOR TO TOPPING POND
Q = CiA
Composite C = 0.8
i100 = 4.15 inlhr for 100 year, 1 hr storm
Q = 0.6(4.15)(8.46) = 21.1 CFS
A. Outlet Weir
As Previously calculated, outlet weir can handle 30.6 CFS which is greater
than 100 yr. flow
B. Outlet Pipe
As calculated previously, outlet pipe will carry 17.5 CFS flowing full which
is less than the 100 yr. flow, therefore, emergency spillway is required.
C. Emergency Spillway
ENG-5
Use Manning's Equation
0.50 ft. deep Trapezoidal Swale with 10 ft. wide bottom and 10:1 side
slopes @ 3.3 Longitudal slope
Use n=0.06 for Grassed Swale
Q=17.5 CFS
Total capacity of Spillway + Outlet Pipes=17.5 + 17.5=35.0 CFS
35.0 CFS > 21.1 CFS
Therefore will handle 100-yr. 1 hr. storm
10. FOREBAY VOLUME
Forebay Volume shall contain approximately 20% of the total permanent
pond volume.
Volume of Permanent Pool 34,887 CF
Forebay Volume Required
34,887 CIF X 20% = 6,977 CIF
Total Volume Provided = 6,900 CIF
c:wpdocs\t ms\a shpon d3. cal
ASHCROFT AT THE COMMONS
ONSLOW COUNTY, NORTH CAROLINA
STORMWATER DETENTION POND #2
ENGINEERING CALCULATIONS
1. AREA
Total Area Draining to Pond from Roads and lots
(including pond area)...................................................................7.82 Acres
Impervious Area:
Roads and Sidewalks................................................................41.043 SF = 0.942 Acres
Houses, driveways and walks ..... 34 Lots x 2400 SF/Lot (Max) = 81,600 SF = 1.873 Acres
Total = 122,643 = 2.816 Acres
Percent Impervious = Impervious = 2.816 = 36 %
Total 7.82
2. PERMANENT POND SURFACE AREA
From Chart 4 - Appendix E from D. E.M. Report 87-05, for 40% impervious,6.0 basin
depth without Vegetative Filter (90% TSS Removal) Yields SA/DA = 2.1 %
7.82 acres x 2.1 % = 0.1642 acres or 7,153 SF surface area required
Top of permanent pond elevation is 43.5
Area at 43.5 elevation = 11,100 SF provided
11,100 SF provided > 7,153 SF required
3. TEMPORARY DETENTION STORAGE VOLUME
Retain 1'' of runoff from impervious area draining to pond
Total Area = 2.816 Acres
Total Runoff = 2.816 Ac.-In.
Find Temporary Storage Volume
2.816 Ac.-In. x 3,630 C.F. = 10,222 C.F. required
AcAn.
o�CF- 1vED
jUL 14 2000
DWa
PpoJ # ���
4. TEMPORARY DETENTION STORAGE VOLUME
Use 1.5 Ft. Temporary Pool
Area at 43.5 elevation (permanent pond) = 11,100 SF
Area at 45.0 elevation (temporary pond) = 13,386 SF
Average Area = 12.243 SF
Storage Vol.= 12,243 SF x 1.5 Height = 18,365 C.F. provided
18,365 C.F. provided > 10,222 C.F. required
5. RELIEVE TEMPORARY STORAGE VOLUME IN 2 TO 5 DAYS
Q = Cd A 2gh (orifice equation)
Q = 10,222 C.F. = 2 days = 0.0592 CFS
Q = 10,222 C.F. = 5 days = 0.0237 CFS
Cd = 0.60
g = 32.2 ft/sec
h = 0.75 average height
For 2 Day Release
Solve For A = Q =
CD 2gh
Solve for Orifice Diameter, D
A=0.0142SF=TTRI
R = 0.0672 ft. = 0.81 inch
D=1.6inch
For 5 Day Release
Solve For A = Q
CDV2gh
0.0592
(0.6) 2(32.2)(0.75)
0.0237
(0.6) 2(32.2)(0.75)
= 0.0142 S.F.
= 0.0057 S.F.
ENG-2
ENG-3
Solve for Orifice Diameter, D
A = 0.0057 SF = n RI
R = 0.043 ft. = 0.51 inch
D = 1.0 inch
Use 1.5 inch diameter orifice
6. SIZE INLET RISER PIPE AND OUTLET PIPES TO HANDLE 10 YR. 1 HR.
STORM
A. Storm Flow
Q =. CiA
A = 7.82 acres
C = 0.6
i = 2.88 in./hr for 10 year 1 hr. storm
Q = 0.6 (2.88) 7.82 = 13.5 cfs
7. Outlet Weir
Water height before topping spillway = 47.0 - 46.5 = 0.5
Q = Cd A 2gh(orifice equation)
Cd = 0.6 (typical valve)
H=0.5
A=9SF
g = 32.2
Q = 0.6(9) 2(32.2)0.5 = 30.6 C.F.S.
Q = 30.6 CFS - Will accept 10 Yr. 1 Hr. Flow
8. Check Gravity Flow
z1►[em
24" Pipe Installed at 0.35%
Use Manning's Equation
Q= 1.49 A R 2/3 S 1/2
n
For 24" Pipe, Q = 13.5 CFS, which is equal to the 10 year - 1 hour flow
Use 24" Pipe
9. DESIGN TO HANDLE 100-YR, 1 HR. STORM THROUGH RISER OUTLET
PIPE AND SPILLWAY PRIOR TO TOPPING POND
Q = CiA
Composite C = 0.8
i100 = 4.15 inlhr for 100 year, 1 hr storm
A = 7.82 Ac.
Q = 0.6(4.15)(7.82) = 19.5 CFS
A. Outlet Weir
As Previously calculated, outlet weir can handle 30.6 CFS which is greater
than 100 yr. flow
B. Outlet Pipe
As calculated previously, outlet pipe will carry 13.5 CFS flowing full which
is less than the 100 yr. flow, therefore, emergency spillway is required.
ENG-5
C. Emergency Spillway
Use Manning's Equation
0.50 ft. deep Trapezoidal Swale with 10 ft. wide bottom and 10:1 side
slopes @ 3.3% Longitudal slope
Use n=0.06 for Grassed Swale
Q=17.5 CFS
Total capacity of Spillway + Outlet Pipes=17.5 + 13.5=31.0 CFS
31.0 CFS > 19.5 CFS
Therefore will handle 100-yr. 1 hr. storm
10. FOREBAY VOLUME
Forebay Volume shall contain approximately 20% of the total permanent
pond volume.
Volume of Permanent Pool 34,887 CF
Forebay Volume Required
34,887 CF X 20% = 6,977 CF
Total Volume Provided = 6,900 CF
c wpdocs\t msW she roft. cal
ASHCROFT AT THE COMMONS
ONSLOW COUNTY, NORTH CAROLINA
STORMWATER DETENTION POND #3
ENGINEERING CALCULATIONS
1. AREA
Total Area Draining to Pond from Roads and lots
(including pond area)...................................................................8.46 Acres
Impervious Area:
Roads and Sidewalks................................................................58,678 SF = 1.347 Acres
Houses, driveways and walks ..... 40 Lots x 2400 SF/Lot (Max) = 96,000 SF = 2.204 Acres
Total=154,678 SF = 3.551 Acres
Percent Impervious = Impervious = 3.551 = 42 %
Total 8.46
2. PERMANENT POND SURFACE AREA
From Chart 4 - Appendix E from D.E.M. Report 87-05, for 45% impervious,6.0 basin
depth without Vegetative Filter (90% TSS Removal) Yields SA/DA = 2.4%
8.46 acres x 2.4% = 0.2030 acres or 8,844 SF surface area required
Top of permanent pond elevation is 44.0
Area at 44.0 elevation = 11,100 SF provided
11,100 SF provided > 8,844 SF required
3. TEMPORARY DETENTION STORAGE VOLUME
Retain 1" of runoff from impervious area draining to pond 0 V EO
Total Area = 3.551 Acres
Total Runoff = 3.551 Ac.-In. �O
O
Find Temporary Storage Volume 001
3.551 Ac.-In. x 3,630 C.F. = 12,890 C.F. required
Ac.-In.
4. TEMPORARY DETENTION STORAGE VOLUME
Use 1.5 Ft. Temporary Pool
Area at 44.0 elevation (permanent pond) = 11,100 SF
Area at 45.5 elevation (temporary pond) = 13,386 SF
Average Area = 12,243 SF
Storage Vol.= 12,243 SF x 1.5 Height = 18,365 C.F. provided
18,365 C.F. provided > 12,890 C.F. required
5. RELIEVE TEMPORARY STORAGE. VOLUME IN 2 TO 5 DAYS
Q = Cd A 2gh (orifice equation)
Q = 12,890 C.F. _ 2 days = 0.0746 CFS
Q = 12,890 C.F. _ 5 days = 0.0298 CFS
Cd = 0.60
g = 32.2 ft/sec
h = 0.75 average height
For 2 Day Release
Solve For A = Q = 0.0746
CD 2gh (0.6) 2(32.2)(0.75)
Solve for Orifice Diameter. D
A=0.0179SF=rrR2
R = 0.076 ft. = 0.91 inch
D=1.8inch
For 5 Day Release
Solve For A = Q
CDV2gh
0.0298
(0.6) 2(32.2)(0.75)
= 0.0179 S.F.
= 0.0071 S.F.
ENG-2
ENG-3
Solve for Orifice Diameter, D
A=0.0071 SF=nRI
R = 0.0477 ft. = 0.572 inch
D = 1.1 inch
Use 1.5 inch diameter orifice
6. SIZE INLET RISER PIPE AND OUTLET PIPES TO HANDLE 10 YR. 1 HR.
STORM
A. Storm Flow
Q = CiA
A = 8.46 acres
C = 0.6
i = 2.88 inAhr. storm
Q = 0.6 (2.88) 8.46 = 14.6 cfs
7. Outlet Weir
Water height before topping spillway = 46.5 - 47.0 = 0.5
Q = Cd A 2gh(orifice equation)
Cd = 0.6 (typical valve)
H = 0.5
A =9SF
g = 32.2
Q = 0.6(9) 2(32.2)0.5 = 30.6 C.F.S.
Q = 30.6 CFS - Will accept 10 Yr. 1 Hr. Flow
8. Check Gravity Flow
24" Pipe Installed at 0.06%
ENG-4
Use Manning's Equation
Q= 1.49 A R 2/3 S 1/2
n
For 24" Pipe, Q = 17.5 CFS, which is equal to the 10 year - 1 hour flow
Use 24" Pipe
9. DESIGN TO HANDLE 100-YR, 1 HR. STORM THROUGH RISER OUTLET
PIPE AND SPILLWAY PRIOR TO TOPPING POND
Q=CiA
Composite C = 0.8
i100 = 4.15 inlhr for 100 year, 1 hr storm
Q = 0.6(4.15)(8.46) = 21.1 CFS
A. Outlet Weir
As Previously calculated, outlet weir can handle 30.6 CFS which is greater
than 100 yr. flow
B. Outlet Pipe
As calculated previously, outlet pipe will carry 17.5 CFS flowing full which
is less than the 100 yr. flow, therefore, emergency spillway is required.
C. Emergency Spillway
ME
ENG-5
Use Manning's Equation
0.50 ft. deep Trapezoidal Swale with 10 ft. wide bottom and 10:1 side
slopes @ 3.3 Longitudal slope
Use n=0.06 for Grassed Swale
Q=17.5 CFS
Total capacity of Spillway + Outlet Pipes=17.5 + 17.5=35.0 CFS
35.0 CFS > 21.1 CFS
Therefore will handle 100-yr. 1 hr. storm
FOREBAY VOLUME
Forebay Volume shall contain approximately 20% of the total permanent
pond volume.
Volume of Permanent Pool 34,887 CF
Forebay Volume Required
34,887 CF X 20% = 6,977 CF
Total Volume Provided = 6,900 CF
c:wpdocsUms%shpond3. ca I
ASHCROFT AT THE COMMONS
ONSLOW COUNTY, NORTH CAROLINA
STORMWATER DETENTION POND #1
ENGINEERING CALCULATIONS
1. AREA
Total Area Draining to Pond from Roads and Lots
(including pond area)...................................................................9.23 Acres
Impervious Area:
Roads and Sidewalks................................................................91,187 SF = 2.093 Acres
Houses, driveways and walks ..... 43 Lots x 2400 SF/Lot (Max) = 103,200 SF = 2.369 Acres
Total = 194,387 SF=4.463Acres
Percent Impervious = Impervious = 4.463 = 48 %
Total 9.23
2. PERMANENT POND SURFACE AREA
From Chart4 -Appendix E from D.E.M. Report87-05, for 50% impervious,6.0 basin
depth without Vegetative Filter (90% TSS Removal) Yields SA/DA = 2.7%
9.23 acres x 2.7% = 0.2492 acres or 10,856 SF surface area required
Top of permanent pond elevation is 42.5
Area at 42.5 elevation = 11,100 SF provided
11,100 SF provided > 10,856 SF required
3. TEMPORARY DETENTION STORAGE VOLUME
Retain 1" of runoff from impervious area draining to pond
Total Area = 4.463 Acres p E C V E D
Total Runoff = 4.463 Ac.-In. JUL 1 4 2000
Find Temporary Storage Volume oWo
PROJ p
4.463 Ac.-In. x 3.630 C.F. = 16,201 C.F. required
Ac.-In.
ENG-2
4. TEMPORARY DETENTION STORAGE VOLUME
Use 1.5 Ft. Temporary Pool
Area at 42.5 elevation (permanent pond) = 11,100 SF
Area at 44.0 elevation (temporary pond) = 13,386 SF
Average Area = 12,243 SF
Storage Vol.= 12,243 SF x 1.5 Height = 18,365 C.F. provided
16,365 C.F. provided > 16,201 C.F. required
5. RELIEVE TEMPORARY STORAGE VOLUME IN 2 TO 5 DAYS
Q = Cd A 2gh (orifice equation)
Q = 16,201 C.F. _ 2 clays— 0.0938 CFS
Q = 16,201 C.F. _ 5 days = 0.0375 CFS
Cd = 0.60
g = 32.2 ft/sec
h = 0.75 average height
For 2 Day Release
Solve For A =
Q = 0.0938 = 0.0225 S.F.
CD 2gh (0.6) 2(32.2)(0.75)
Solve for Orifice Diameter, D
A = 0.0225 SF = TT R2
R = 0.085 ft. = 1,06 inch
D=2.Oinch
For 5 Day Release
Solve For A = Q = 0.0375 = 0.0090 S.F.
CD 2gh (0.6)� 2(32
ENG-3
Solve for Orifice Diameter, D
A = 0.0090 SF = n RI
R = 0.054 ft. = 0.642 inch
D = 1.3 inch
Use 1.5 inch diameter orifice
6. SIZE INLET RISER PIPE AND OUTLET PIPES TO HANDLE 10 YR. 1 HR.
STORM
A. Storm Flow
Q = CA
A = 9.23 acres
C = 0.6
i = 2.88 in./hr. - 10 year, 1 hr. storm
Q = 0.6 (2.88) 9.23 = 15.9 cfs
7. Outlet Weir
Water height before topping spillway = 46.0 - 45.5 = 0.5
Q = Cd A 2gh(orifice equation)
Cd = 0.6 (typical valve)
H = 0.5
A=9SF
g = 32.2
Q = 0.6(9) 2(32.2)0.5 = 30.6 C.F.S.
Q = 30.6 CFS - Will accept 10 Yr. 1 Hr. Flow
8. Check Gravity Flow
ENG-4
24" Pipe Installed at 0.50%
Use Manning's Equation
Q= 1.49 A R 2/3 S 1/2
n
For 24" Pipe, Q = 16.0 CFS, which is equal to the 10 year - 1 hour flow
Use 24" Pipe
9. DESIGN TO HANDLE .100-YR. 1 HR. STORM THROUGH RISER, OUTLET
PIPE AND SPILLWAY PRIOR TO TOPPING POND
Q = CiA
Composite C = 0.6
iloo = 4.15 inlhr for 100 year, 1 hr storm
Q = 0.6(4.15)(9.23) = 23.0 CFS
A. Outlet Weir
As Previously calculated, outlet weir can handle 30.6 CFS which is greater
than 100 yr. flow
B. Outlet Fipe
As calculated previously, outlet pipe will carry 16.0 CFS flowing full which
is less than the 100 yr. flow, therefore, emergency spillway is required.
C. Emergency Spillway
10
ENG-5
Use Manning's Equation
0.50 ft. deep Trapezoidal Swale with 10 ft. wide bottom and 10:1 side
slopes @ 3.3% Longitudal slope
Use n=0.06 for Grassed Swale
Q=17.5 CFS
Total capacity of Spillway + Outlet Pipes=17.5 + 16.0=33.5 CFS
33.5 CFS > 23.0 CFS
Therefore will handle 100-yr. 1 hr. storm
FOREBAY VOLUME
Forebay Volume shall contain approximately 20% of the total permanent
pond volume.
Volume of Permanent Pool 34,887 CF
Forebay Volume Required
34,887 CF X 20% = 6,977 CF
Total Volume Provided = 6,900 CF
c:wpdocs\tms�ashpondi .cal
State of North Carolina
Department of Environment
and Natural Resources
Wilmington Regional Office
.lames B. Bunt, Jr., Governor
Bill Holman, Secretary
Division of Water Quality
Mr. Tiro Stewart, P.E.
Parker $ Associates, Inc.
PO Box 976
Jacksonville, NC 28540
Dear Mr. Stewart:
June 30, 2000
NCDENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RE OURCE5
Subject: ACKNOWLEDGMENT OF RECEIPT AND
REQUEST FOR ADDITIONAL INFORMATION
Stormwater Project No. SW8 000505
Ashcroft at The Commons
Onslow County
The Wilmington Regional Office received a Stormwater Management Permit Application for
Ashcroft at The Commons on May 1, 2000. A preliminary review of that information has determined that
the application is not complete. The following information is needed to continue the stormwater review:
1. Please hand initial the blanks on the application and all 3 supplement forms. Typed initials
cannot be accepted.
2. Please base the draw down orifices on the volume that is required and not on the volume that
is provided. Resubmit the calculations and two copies of the details showing the new orifice
diameters proposed.
Please note that this request for additional information is in response to a preliminary review. The
requested information should be received by this Office prior to July 30, 2000, or the application will be
returned as incomplete. The return of a project will necessitate resubmittal of all required items, including
the application fee.
If you need additional time to submit the information, please mail or fay your request for a time
exteninn ,.o tllc Division at t;le ado: ---ss and fax number at the bottom of this letter. The request must
indicate the date by which you expect to submit the required information. The Division is allowed 90
days from the receipt of a completed application to issue the permit.
The construction of any impervious surfaces, other than a construction entrance under an approved
Sedimentation Erosion Control Plan, is a violation ofNCGS 143-215.1 and is subject to enforcement action
.pursuant io NCGS 143-215.6A.. ...
Please reference the State assigned project number on all correspondence. Any original documents
that need to be revised have been sent to the engineer or agent. All original documents must be returned or
new originals must be provided. Copies are not acceptable. If you have any questions concerning this matter
please feel free to call me at (910) 395-3900. -
Sincerely,
Cott Vinson
Environmental Engineer
RSS/sav: S:\WQS\STORMWAT\ADDINFO\000505.NN
cc: Wilmington Regional Office
Ernest D. Hackney, 1st Wilmington Properties
127 Cardinal Dr. EXL, Wilmington, North Carolina 28405 Telephone 910-395-3900 FAX 910-350-2004
An Equal Opportunity Affirmative Action Employer 50% recycled/10 post -consumer paper
PARKER & ASSOCIATES, INC.
Consulting Engineers - Land Surveyors - Land Planners
306 New Bridge Street - P.O. Box 976
Jacksonville, NC 28541-0976
(910) 455-2414 - Fax: (910) 455-3441
LETTER OF TRANSMITTAL
TO: Ms. Linda Lewis
NCDENR-Division of Water Quality
127 Cardinal Drive Extension
Wi mington, NC 28405-3845
DATE: April 27, 2000
REF: Ashcroft at The Commons
Onslow County, NC
Stormwater Control Submittal
WE ARE SENDING YOU:
One (1) original and one (1) copy of the Stormwater Submittal Form,
including Narrative and Calculations, Supplement Forms, two (2) sets of
Plans and Specifications, one (1) Review Fee Check for $420.00, and one (1)
copy of the Stormwater Submittal Plan all for the above referenced project.
DELIVERY VIA:
M REGULAR NAIL ❑ HAND
❑ UPS OVERNIGHT ❑ UPS GROUND
THESE ARE TRANSMITTED AS CHECKED BELOW:
6 FOR APPROVAL ❑ AS REQUESTED
❑ FOR YOUR USE
❑ OTHER
COMMENTS:
Linda,
❑ FOR BIDS DUE
❑ FEDERAL EXPRESS
❑ OTHER
❑ FOR REVIEW AND COMMENT
This package is being resubmitted per your letter dated April 19, 2000.
We now have original signatures on all Wet Pond Supplement Forms. Also, the
Developer name has changed from Linden Ridge Partners to 1st Wilmington
ies.
t,
COPIES TO: Mr. Tom Anderson
Mr. Beetrrs Hackney
TMS/hjb CF (P)
Enclosures
(IF ENCLOSURES ARE NOT AS NOTED, XZNDLY NOTIFY US AT ONCE)
Pennit No. JOe 6605b
(to be provided by DW&
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWO Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention .basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: Ashcroft at The Commons
Contact Person: Deans Hackney Phone Number: (910 ) 763 1741
For projects with multiple basins, specify which basin this worksheet applies to: 3
elevations
Basin Bottom Elevation
38.0
ft.
(floor of the basin)
Permanent Pool Elevation
44.0
ft.
(elevation of the orifice)
Temporary Pool Elevation
45.5
ft.
(elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area
11,100
sq.
ft.
(water surface area at the orifice elevation)
Drainage Area
8.46
ac.
(on -site and off -site drainage to the basin)
Impervious Area
3,551
ac.
(on -site and off -site drainage to the basin)
volumes
Permanent Pool Volume
34,887
cu.
ft.
(combined volume of main basin and forebay)
Temporary Pool Volume
18,365
cu.
ft.
(volume detained above the permanent pool)
Forebay Volume
6,900
cu.
ft.
(approximately 20% of total volume)
Other parameters
SAIDA[
7.4%
(surface area to drainage area ratio from DWQ table)
Diameter of Orifice
1 •5
in.
(2 to 5 day temporary pool draw -down required)
Design Rainfall
t
in.
Design TSS Removal Z
9n
%
(minimum 85% required)
Form SwU-10'_ Rev 3,90 Page 1 01' 4
Footnotes:
When using the Division SAIDA tables, the correct SAIDA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
TS a.
TSS b.
Tfl5 C.
_66 d.
TM, N%jA ; e.
The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
The forebay volume is approximately equal to 20% of the basin volume.
The temporary pool controls runoff from the design storm event.
The temporary pool draws down in 2 to 5 days.
If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
f. The basin length to width ratio is greater than 3:1.
g. The basin side slopes above the permanent pool are no steeper than 3:1.
It. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
i. Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
�M) ` k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
TM� 1. If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
IM) * m. A mechanism is specified which will drain the basin for maintenance or an emergency.
*k: Will be recorded at a later time
*m: If pond ever has to be drained, a pump will be used
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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) 0 does ® does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does 9 does not incorporate pretreatment other than a forebay.
Form SWIJI-102 Rev 3.0`t Rigc 2 of d
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs
within 2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet detention basin or stream, etc.).
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 4. 5 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4. 5 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(flll in the blanks)
t�� r
Permanent Pool Elevation 44;.0'-'•,
Sediment RetEleat
. ,;.; n
__ Sediment Removal Elevation 39 . 5 75%
Bottom38. 0 %--------------------------------------------- ----
Bottom Elevation 38 . 0 25%
FOREBAY MAIN POND
5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
\ Form SWU-102 Rev 3.99 Page 3 of 4
1
All components of the �ket detention basin system shall be maintained in good working order.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
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.
Print name: Ernest Heanc Hackney
Title: General Partner
IN
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, _Cle,-2 ✓4 S 7-�� a Notary Public for the State of �✓or�� C °�:�Q
County of do hereby certify that f . i/earls (lrac�ne h
personally appeared before me this 26 day of 7000 , and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
'1060TAR�.'•�
,o. pUBL�G:
?s�OW
co13N�y?';
.SEAL
My commission expires
Form SWU-102 Rev 3.99 Page 4 of 4
Permit No. cswD QQ7 s0.7
(to be provided bY DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention ,basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: Ashcroft at'The Commons
Contact Person: Deans Hackney Phone Number: 1 91,
For projects with multiple basins, specify which basin this worksheet applies to:
elevations
Basin Bottom Elevation 37.5 ft.
Permanent Pool Elevation 43.5 ft.
Temporary Pool Elevation 45.0 ft.
763 1741
t,
(floor of the basin)
(elevation of the orifice)
(elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area 11,100 sq. ft. (water surface area at the orifice elevation) ,
Drainage Area 7.82 ac. (on -site and off -site drainage to the basin)
Impervious Area 2.816 ac. (on -site and off -site drainage to the basin)
volumes
Permanent Pool Volume 34,887 cu. ft. (combined volume of main basin and forebay)
Temporary Pool Volume 18,365 cu. ft. (volume detained above the permanent pool)
Forebay Volume 6,900 cu. ft. (approximately 20% of total volume)
Other parameters
SA/DA( 2.1% (surface area to drainage area ratio from DWQ table)
Diameter of Orifice 1.5 in. (2 to 5 day temporary pool draw -down required)
Design Rainfall 1 in.
Design TSS Removal 2 90 % (minimum 85% required)
Form SW(J-102 Rev 3.99 Pale I of 4
Footnotes:
When using the Division SA/DA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual.provides design tables for both 85% TSS removal and 90% TSS removal.
H. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
-W ;
Tat
TMi
TMS J -
(tnl NZA
a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
b. The forebay volume is approximately equal to 20% of the basin volume.
e. The temporary pool controls runoff from the design storm event.
d. The temporary pool draws down in 2 to 5 days.
e. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
f. The basin length to width ratio is greater.than 3:1.
g. The basin side slopes above the permanent pool are no steeper than 3:1.
It. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
i. Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
TMi 1. If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
tN�ti * m. A mechanism is specified which will drain the basin for maintenance or an emergency.
*k: Will be recorded at a later time
*m: If pond ever needs to bewdrained, a pump will be used
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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) 0 does A does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does ddoes not incorporate pretreatment other than a forebay.
Form Swu-lo'_ Rev 399 Paige 2 of d
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs
within 2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet detention basin or stream, etc.).
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 4 - s feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4. 5 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
ill in the blanks)
Permanent Pool Elevation 43 , 5
Sediment Re oval El. 3 g p 75 b
______________ _ Sediment Removal Elevation3�
------------------------------75%
Bottom Ele anon 37 .5 %----------------------
Bottom Elevation i 7 - S 25% /
FOREBAY MAIN POND
Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
1 Form SWU-l02 Rev 3.99 Pave 3 of 4
All ComponCM< of IhC wet dr::nlion hasin system shall be maintained in good working order.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed abo%e. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Ptintname: Ernest Deans Hackney
General Partner
Address: P.O. Box 3442, Wilmgngton, NC 28406
La Le
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, — � / Ge,u S a Notary Public for the State of
County of ,1 ?, l-rvvYcK , do hereby certify that C.
personally appeared before me this �`� day of 4 (_ dO 6, and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
�u.Cc4.Li
tT : ! �.
NOT '•.
Z v v •': z
t
CDUNT'I
/ttlttttN SEAL
My commission expires 2 -j -d-
Form SWU-102 Rev 3.99 Page 4 of 4
., eF ,. ,..... �".a ..• at'
.`_z=.OFFICE USE ONLY Qw:...,�-
Date Received
Fee Paid
Permit Number
S-4-00
°� 08
U) D .�5
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form may be photocopied for use as an original
1. GENERAL INFORMATION
1. Applicants name (specify the name of the corporation, individual, etc. who owns the project):
1st Wilmington Properties
2. Print Owner/Signing Official's name and title (person legally responsible for facility and compliance):
Ernest D. Hackney_, Ceneral Partner --
3. Mailing Address for person listed in item 2 above:
P.O. Box 3442
City: Wilmington State: Nr zip:4Ab
Telephone Number: ( 910 ) 7 6 9- 1 76 4
4. Project Name (subdivision, facility, or establishment name - should be consistent with project name on
plans, specifications, letters, operation and maintenance agreements, etc.):
Ashcroft at The Commons
5. Location of Project (street address):
Commons Drive South and Fairway Road
City: Jacksonville County: 0 n % I o w
6. Directions to project (from nearest major intersection):
On Western Boulevard Extent6on turn onto Gateway Drive South, Fhen turn
onto Commons Drive South then turn right on West Fairway Road, arrnss from
Northside High School
7. Latitude: N 34 14 7 ' 2 0 " Longitude: W 7 7 ° 2 3 ' 31 " of project
8. Contact person who can answer questions about the project:
Deans Hackne
IT. PERMIT INFORMATION:
1. Specify whether project is (check one):
Telephone Number: ( 910 ) 7 6 3-17 6 4
x New
Renewal Modification
Form SWU-101 Version 3.99 Page 1 of 4
2. If this application is being submitted as the result of a renewal or modification to an existing permit, list the
existing permit number and its issue date (if known)
3. Specify the type of project (check one):
_Low Density X High Density _Redevelop _General Permit _Other
4. Additional Project Requirements (check applicable blanks):
_LAMA Major XSedimentation/Erosion Control _404/401 Permit _NPDES Stormwater
Information on required state permits can be obtained by contacting the Customer Service Center at
1-877-623-6748.
III. PROJECT INFORMATION
1. In the space provided below, summarize how stormwatei will be treated. Also attach a detailed narrative
(one to two pages) describing stormwater management for the project.
Subdivision will drain to three stormwater ponds
2. Stormwater runoff from this project drains to the
3. Total Project Area: 29.03 acres
White Oak
5. How many drainage areas does the project have? 3
River basin.
4. Project Built Upon Area: 37.3
6. Complete the following information for each drainage area. If there are more than two drainage areas in the
project, attach an additional sheet with the information for each area provided in the same -format as below.
Pond #1 Pond #2
Pond #3
BasuiIIriformation 9
e�� r... "�ra f,.
x�SxF+`*
e ",< :, svwe.,.�.-,_.
, Al p,
.�
Receiving Stream Name
Northeast Creek
Northeast Creek
14ortheast Creek
Receiving Stream Class
S C NSW
se NSW
Drainage Area
Existing Impervious* Area
0
0
0
Proposed Irn ervious"Area
4.463 Acres
2.816 Acres
3.551 Acres
% Im ervious Area (total)
48%
36%
42%
ervtousM Surface Area, ¢
hDa
,
2
On -site Buildings &drives
103,200 SF
81,600 SF
96,000 SF
On -site Streettsidewalks
On -site -Parking -
On -site Sidewalks -
Other on -site
Off -site
Total: 19
387 F=4463
-
-
" Impervious area is defined as the built upon area including, but not limited to, buildings, roads, parking areas,
sidewalks, gravel areas, etc. 43 L k Q 34 ID-k- @ 40 l,,is e
7."I'vsr. d,10DSir A,yso sr.
Form SWU-101 Version 3.99 Page 2 of 4
7. How was the off -site impervious area listed above derived? N / A
IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
The following italicized deed restrictions and protective covenants are required to be recorded for all
subdivisions, outparcels and future development prior to the sale of any lot. if lot sizes vary significantly, a
table listing each lot number, size and the allowable built -upon area for each lot must be provided as an
attachment.
1. The following covenants are intended to ensure ongoing compliance with state stormwater management permit
number. 5W 9' coo J 0S as issued by the Division of Water Quality. These covenants may
not be changed or deleted without the consent of the State.
2. No more than 2,400 square feet of any lot shall be covered by structures or impervious materials.
Impervious materials include asphalt, gravel, concrete, brick, stone, slate or similar material but do not include wood
decking or the water surface of swimming pools.
3. Swales shall not be filled in, piped, or altered except as necessary to provide driveway crossings.
4. Built -upon area in excess of the permitted amount requires a state stormwater management permit modification prior to
construction.
5. All permitted runoff from outparcels or future development shall be directed into the permitted stormwater control
system. These connections to the stormwater control system shall be performed in a manner that maintains the
integrity and performance of the system as permitted.
By your signature below, you certify that the recorded deed restrictions and protective covenants for this project
shall include all the applicable items required above, that the covenants will be binding on all parties and
persons claiming under them, that they will run with the land, that the required covenants cannot be changed or
deleted without concurrence from the State, and that they will be recorded prior to the sale of any lot.
V. SUPPLEMENT FORMS
The applicable state stormwater management permit supplement form(s) listed below must be submitted for
each BMP specified for this project. Contact the Stormwater and General Permits Unit at (919) 733-5083 for the
status and availability of these forms.
Form SWU-102
Wet Detention Basin Supplement
Form SWU-103
hifiltration Basin Supplement
Form SWU-104
Low Density Supplement
Form SWU-105
Curb Outlet System Supplement
Form SWU-106
Off -Site System Supplement
Form SWU-107
Underground Infiltration Trench Supplement
Form SWU-108
Neuse River Basin Supplement
Form SWU-109
Innovative Best Management Practice Supplement
Form SW U-101 Version 3.99 Page 3 of 4
VI. SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Water Quality (DWQ).
A complete package includes all of the items listed below. The complete application package should be
submitted to the appropriate DWQ Regional Office.
1. Please indicate that you have provided the following required information by initialing in the space
provided next to each item.
• Original and one copy of the Stormwater Management PermInitials it Application Form �f ffi 5
• One copy of the applicable Supplement Form(s) for each BMP - 6
• Permit application processing fee of $420 (payable to NCDENR)
• Detailed narrative description of stormwater treatment/management
• Two copies of plans and specifications, including: 1MS
- Development/Project name
- Engineer and firm
-Legend
- North arrow
- Scale
- Revision number & date
- Mean high water line
- Dimensioned property/project boundary
- Location map with named streets or NCSR numbers
- Original contours, proposed contours, spot elevations, finished floor elevations
- Details of roads, drainage features, collection systems, and stormwater control measures
- Wetlands delineated, or a note on plans that none exist
- Existing drainage (including off -site), drainage easements, pipe sizes, runoff calculations
- Drainage areas delineated
- Vegetated buffers (where required)
VII. AGENT AUTHORIZATION
If you wish to designate authority to another individual or firm so that they may provide information on your
behalf, please complete this section. .
Designated agent (individual or firm): Parker & Associates, Inc.
Mailing Address: P.O. Box 976,
City: Jacksonville State: NC Zip: 28540
Phone:( 910 ) 455- 2414 Fax: ( 910 ) 455.3441
VIII. APPLICANT'S CERTIFICATION
I, (print or type name of person listed in General Information, item 2) Frnest Deans Hackney
certify that the information included on this permit application form is, to the best of my knowledge, correct and
that the project will be constructed in conformance with the approved plans, that the required deed restrictions
and protective covenants will be recorded, and that the proposed project complies with the requirements of 15A
NC'AC' 7H 1non
Date: Y-6 -00
Form SWU-101 Version 3.99 Paee 4 of 4
Permit No.'So'g'966 SQ�
(to be provided by DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: Ashcroft at The Commons
Contact Person: Deans Hankne)4 Phone Number: ( 910) 763 1764
For projects with multiple basins, specify which basin this worksheet applies to: 1
elevations
Basin Bottom Elevation 36.5 ft.
Permanent Pool Elevation 42.5 ft.
Temporary Pool Elevation 4.4.0, ft.
(floor of the basin)
(elevation of the orifice)
(elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area 11 �t oo sq. ft. (water surface area at the orifice elevation)
Drainage Area
Impervious Area
volumes
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
Other parameters
SA/DA 1
Diameter of Orifice
Design Rainfall
Design TSS Removal 2
9.23 ac. (on -site and off -site drainage to the basin)
4,463 ae. (on -site and off -site drainage to the basin)
34,887 cu. ft. (combined volume of main basin and forebay)
1 8t 365 cu. ft. (volume detained above the permanent pool)
6,900 cu. ft. (approximately 20% of total volume)
2 -71Y
1 .5 in.
1 in.
(surface area to drainage area ratio from DWQ table)
(2 to 5 day temporary pool draw -down required)
90 % (minimum 85% required)
Form S W U-102 Rev 3.99
Page I of 4
Footnotes:
When using the Division SAIDA tables, the correct SAIDA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
_W _ a.
(mi b.
(Ml. C.
d.
7t�ti NSA " e.
-frA,
:L(Al
lr�
Tt~�
_W
The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
The forebay volume is approximately equal to 20% of the basin volume.
The temporary pool controls runoff from the design storm event.
The temporary pool draws down in 2 to 5 days.
If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
The basin length to width ratio is greater than 3:1.
g. The basin side slopes above the permanent pool are no steeper than 3:1.
h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
i. Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
1. If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
"y in. A mechanism is specified which will drain the basin for maintenance or an emergency.
*k: will be recroded at a later date
*m: If pond ever has to be drained, a pump will be used.
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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) 0 does 0 does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does Q does not incorporate pretreatment other than a forebay.
Form SWU-102 Rev 3.99 Page 2.of 4
Maintenance activities shall be performed as follows:
1. After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs
within 2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet detention basin or stream, etc.).
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 4.,5_ feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4.5 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 42 9
Sediment Re ovalEl. 38.0 75
--""""' - Sediment Removal Elevation 3a n Bottom Ele Ptio75%
n 3r_5 % --------------------------
--------------
Bottom Elevation 25%
FOREBAY MAIN POND
Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
Form SWU-102 Rev 3.99
Page 3 of 4
All components of the wet detention basin system shall be maintained in good working order.
1 acknowledge and agree by my signature below that I am responsible for the performance of the seven
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.
A
Print name:
V V
Title: t-
nrirlrPcc• OUgc) �
Date: 'd/'G - 00
Note: The legally responsible patty 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 C22dL 61?,O,y , a Notary Public for the State of Mw-11L
County of A . ' do hereby certify that
personally appeared before me this GYM .day of" 412
Zoo o , and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
LEW�S"'�ii��'
zi �>
m `• aue�-sG.�2
/V E� 0
SEAL
My commission expires %
m4W-d`�
i SWU-102 Rev 3.99 Page 4 of 4