SW8931204_Historical File_19940802

State of North Carolina
Department of Environment, Health, and Natural
Wilmington Regional Office
James B. Hunt, Jr., Governor DIVISION OF ENVIRONMENTAL MANAGEMENT
Jonathan B. Howes, Secretary WATER QUALITY SECTION
August 2, 1994
Mr. Darius Stanaland
W. M. Stanaland Estate, Inc.
1157 River Road
Calabash, North Carolina 28467
ResourceR
Bob Jamieson
Regional Manager
Subject: CERTIFICATION OF COMPLIANCE
with Stormwater Regulations
Stormwater Project No. 931204
Ocean, Harbour Estates
Brunswick County
Dear Mr. Stanaland:
This Certification is pursuant to the revised application for Ocean Harbour Estates received on
June 9, 1993, with additional information received July 27, 1994. Staff review of the project plans and
specifications has determined that the stormwater control system as proposed will comply with the
Stormwater Regulations set forth in Title 15A NCAC 2H.1003(h). Stormwater runoff will be treated by
an infiltration trench system sized to contain the first 1-1/2" of runoff from 271,379 square feet of built
upon surfaces located on site. This Certification supersedes the one issued to you on February 8, 1994
and covers the revision to a collection/infiltration system.
Any modification of the plans submitted to and approved by this Office or further development
of this site regardless of the fact that such modification may be less than 1 acre, will require an additional
Stormwater Submittal/Modification and approval prior to initiation of construction. Modifications include
but are not limited to; project name changes, transfer of ownership, redesign of built -upon surfaces,
addition of built -upon surfaces, redesign or further subdivision of the project area as shown on the plans
submitted to and approved by this Office.
This Certification shall be effective from the date of issuance until rescinded. The project shall
be constructed and maintained in accordance with the plans and specifications approved by the
Wilmington Regional Office. The developer is responsible for obtaining any and all permits and approvals
necessary for the development of this project. This could include the Division of Coastal Management
under CAMA requirements, The Division of Environmental Management under Wetland 401 Water
Quality Certification, and/or a Dredge and Fill Permit, and/or a Sewer Extension/Collection Permit, U.S.
Army Corps of Engineers 404 Wetland Permit, NPDES Stormwater Permit if disturbing five acres or
more, local County or Town Agency permits under their local ordinances, or others that may be required.
127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 C Telephone [phone] O Fax [phone]
An Equal Opportunity Affirmative Action Employer

Mr. Stanaland
August 2, 1994
Stormwater Project No. 931204
A professional engineer must certify that the stormwater system has been installed in accordance
with the approved plans and specifications upon completion of construction. The attached certification
should be received by this Office within 30 days of construction completion.
Deed restrictions for the 38 lots at 5,305 square feet built -upon area per lot, must be recorded
with the Office of the Register of Deeds. A copy of the recorded deed restrictions, including deed book
number and page, must be forwarded to this Office within 30 days of the date of the recording. Failure
to record and/or submit the deed restrictions to this Office is considered a violation of this Certification.
The infiltration structure shall be constructed in it's entirety, the overflow swales permanently
vegetated and operational prior to the construction of any impervious surfaces proposed for the project,
except roads.
If you have any questions concerning this matter, please call Ms. Linda Lewis or me at (910)-
395-3900.
Sincerely,
Dave Adkins
Water Quality Supervisor
DA/arl: S:\WQS\STORMWAT\CERTIFIC\931204.AUG
cc: Robert Castles, P.E.
Robert Tucker, P.E. Brunswick County Building Inspections
Bradley Bennett
Linda Lewis
Wilmington Regional Office
Central Files

DIVISION OF ENVIRONMENTAL MANAGE DENT
INFILTRATION SYSTEM PROJECT DATA
Project Name:
Project No.:
Location:
Applicant Name:
Mailing Address:
Submittal Date:
Water Body Receiving Stormwater Runoff:
Classification of Water Body:
Trench size:
Trench Depth:
Bottom Elevation:
Design Storage Elevation:
Total Impervious Surfaces Allowed:
Green Areas Draining to Basin:
Storage volume required:
Storage volume provided:
Infiltration Rate and Type of Soil:
Comments:
Ocean Harbour Estates
931204
Brunswick
Mr. Darius Stanaland
W. M. Stanaland Estate, Inc.
1157 River Road
Calabash, North Carolina 28467
June 9, 1993
AIWW
4' x 4' x 1127' with 24" ADS-N12 perforated pipe.
5'min. In
Lowest- 21.5 MSL, highest- 29.7 MSL
Lowest- 25.5 MSL, highest- 33.7 MSL
271,379 square feet, 38 lots @ 5,305 SF/lot
187,630 square feet
10,139 cubic feet
10,139 cubic feet (see comments)
Sand, 200 in/hr
This design assumes that there is infiltration occurring during the storm event, so that the volume
of storage required is equal to the runoff volume generated minus the initial volume that infiltrates.

INFILTRATION SYSTEM EVALUATION
1.
Yes
No
System is capable of treating and disposing of runoff from all impervious
surfaces resulting from 1-1/2 inches of rain.
2.
Yes
No
The system is located at least 30 feet from surface waters.
3.
Yes
No
The system is a minimum of 100 feet from water supply wells.
4.
Yes
No
The bottom of the system is a minimum of 2 feet above the seasonal high
water table.
5.
Yes
No
Runoff in excess of the design volume by-passes the system and does not flush
pollutants through the system.
6. Yes No The vegetative filter provides non -erosive flow for the 10 year storm, even
distribution of the runoff over the length of the filter, a slope of 5 % or less,
and is planted with natural, grassed, or artificially planted wetland vegetation.
7.
Yes
No
The system has been shown to completely draw down in 5 days.
8.
Yes
No
Soil has a minimum hydraulic conductivity of 0.52 in/hr.
9.
Yes
No
The system is not sited on or in fill material.
10.
Yes
No
The system has an observation well.
11.
Yes
No
An Operation and Maintenance plan has been provided for the system.
12. Yes No THIS PROJECT MEETS THE STORMWATER CONTROL
REQUIREMENTS OF 15 NCAC 2H. (g), (h), 6), (k) and (1). For YES,
items 1-12 must all be highlighted YES.
DIVISION OF ENVIRONMENTAL MANAGEMENT SIGN -OFF
Wilmington Regional Office
Z AQG 9+
Date
v 1
D
Z�LaST- ��
4
Date
Indiv' ual Evaluating Form/Plans
Regional Soil Scientist
Regional Water Quality Supervisor
cc:Applicant/Bradley Bennett/arl/WiRO/CF

Ocean Harbour Estates
Brunswick County
Stormwater Project No. 931204
Engineer's Certification
I, , as a duly registered Professional Engineer 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. Recorded deed restrictions are attached to provide further evidence that the project has
been built within substantial intent of the approved stormwater plans and spcctffications.
Signature
Registration Number
Date

I. or r.? r
CASTLES CONSULTING ENGINE [RS I Cr
2411 Oak St. Suite 3 k
MYRTLE BEACH, SOUTH CAROLI c + 29 �JUL 2 5
[phone] -"""
FAX [phone]-,,,,....
To State of North Carolina
DEHNR
127 Cardinal Drive Est.
Wilmington, NC 28405-3845
i�
DAT€ Jjil 21, 1904
GCB NO.
A7NTION
Ms. Linda Lewis
RE:
Ocean Harbour Estates
WE ARE SENDING YOU _I Attached ❑ Under separate cover via the following items:
❑ Shop drawings
❑ Copy of letter
X Prints
❑ Change order
❑ Plans ❑ Samples ❑ Specifications
pN Calculations
COPIES
DATE
NO.
DESCRIPTION
3
7/21/94
Revised Road plan
3
7/21/94
Calculations for swales �-
PROP # 9�1�
THESE ARE TRANSMITTED as checked below:
X For approval
❑ For your use
❑ As requested
❑ For review and comment
❑ Approved as submitted
0 Approved as noted
❑ Returned for corrections
❑ Resubmit
❑ Submit
❑ Return
copies for approval
copies for distribution
corrected prints
❑ FORBIDS DUE 19 ❑ PRINTS RETURNED AFTER LOAN TO US
REMARKS Per your letter of July 8, 1994 and subsequent phone conversation
we have revised the enclosed drawing and provided calculations. Based on
our conversation, we are assuming this additional information is all that
will be required for approval. If, however, there is additional information
you need, please contact me.
COPY TO
RECYCLED PAPER:
Contents: 40% Pre -Consumer -10% Post -Consumer
SIGNE
/f enclosures are not as noted, kindly notify us at once.

rl
CIVIL SOFTWARE DESIGN
SEDCAD+ Version 3
VEGETATIVE CHANNEL #1 CALCULATIONS FOR 10--YEAR, 24---HOUR STORM_
S r I
of
TOMMINATER
p C�C[�OVI�
UD
'�' JUL 2 ? 1994
DEM
QRos #, q3 rZ04
Name. DN
Company Name: CASTLES CONSULTING ENGINEERS
File Name: B.\HARBOUR2
Date: 07--21-1994

Civil Software Design .-�- SEDCAD+ Version 3.1
Copyright (C) 1987-1992. Pamela J. Schwab. All rights reserved.
Company Name: CASTLES CONSULTING ENGINEERS
Filename: B:\HARBOUR2 User: DN
Date: 07-21-1994 Time: 08:36:27
VEGETATIVE CHANNEL #1 CALCULATIONS FOR 10-YEAR, 24--HOUR STORM..
Storm: 6.55 inches— 10 year--24 hour, SCS Type III
Hydrograph Convolution.Interval: 0.1 hr
SUBWATERSHED/STRUCTURE INPUT/OUTPUT TABLE--
-Hydrology--
Base-
Runoff
Peak
JBS
SWS
Area
CN UHS
Tc
K X
Flow
Volume
Discharge
(ac)
(hrs)
(hrs)
(cfs)
(ac-ft)
(cfs)
ill
1
2.08
55 M
0.167
0.000 0.000
0.0
0.32
2.21
111
2
1.66
56 M
0.250
0.000 0.000
0.0
0.27
1.71
Type.
Vegetated
Channel
Label:
VEGETATIVE
CHANNEL 3
Ill
Structure
3.74
0.59
111
Total IN/OUT
3.74
0.59
3.81

Civil Software Deign -- SEDCAD+ Version 3.1
Copyright (C) 1987-1992. Pamela J. Schwab. All rights reserved..
Company Name: CASTLES CONSULTING ENGINEERS
Filename: B:4HARBOUR2 User: DN
Date: 07-21-1994 Time: 08:36:27
VEGETATIVE CHANNEL #1 CALCULATIONS FOR 10-YEAR, 24-HOUR STORM.
Storm: 6.55 inches, 10 year-24 hour, SCS Type III
Hydrograph Convolution Interval: 0.1. hr
_______________________________________
NON -POND STRUCTURE INPUT/OUTPUT TABLE
J1, B1, S1
VEGETATIVE CHANNEL 3
Drainage Area from J1, B1, S1, SWS(s)1-2. 3.7 acres
Total Contributing Drainage Area: 3.7 acres
MATERIAL: BERMUDA GRASS
Trapezoidal Vegetated Channel
Limiting Variablo: Velocity = 7.000 fps
Design Bottom
Discharge Width ZLeft ZRight
Slope
(cfs) (ft)
(%)
3.81 12.0 2.0:1 2„0:1
7.0
Top Manning's
Hydraulic
Froude
Retardance
Depth Velocity Width N
Radius
Number
Class
(ft) (fps) (ft)
Stability B
0.43 0.69 13.7 0.310
0.396
0.19
Capacity B
0.43 0.69 13.7 0.310
0.396
0.19
w/ Freeboard + B
0.43 13.7
Runoff Peak
Volume Discharge
(ac--ft) (cfs)
IN/OUT 0.59 3.81

C
CIVIL SOFTWARE DESIGN
SEDCAD+ Version 3
VEGETATIVE CHANNEL #2 CALCULATIONS FOR 10-YEAR, 24-HOUR STORM.
h
by
Name: DN
Company"Name: CASTLES CONSULTING ENGINEERS
File Name: B:\HARBOURI
Date: 07-21-1994

Civil Software Design -- SEDCAD+ Version 3.1
Copyright (C) 1987-1,992. Pamela J. Schwab. All rights reserved_
Company Name: CASTLES CONSULTING ENGINEERS
Filename: B:\HARBOURI User: DN
Date: 07-21-1994 Time: 08:37:11
VEGETATIVE CHANNEL #2 CALCULATIONS FOR 1.0-YEAR, 24-HOUR STORM.
Storm. 6.55 inches,, 10 year-24 hour, SCS Type T.TT
Hydrograph Convolution Interval: 0.1 hr
SUBWATERSHED/STRUCTURE INPUT/OUTPUT TABLE
-Hydrology-
Base-
Runoff
Peak
JBS
SWS
Area CN
UHS Tc
K X
Flow
Volume
Discharge
(ac)
(hrs)
(hrs)
(cfs)
(ac-ft)
(cfs)
3.61 59
M 0.334
0.000 0.000
0.0
0.66
3.89
Type:
Vegetated
Channel
Label: OCEAN
HEARBOUR
II
Structure
3.61
0.66
------------------------------------------------------
1.11
Total IN/OUT
3.61
-------------------------
0.66
3.89

Civil Software Design -- SEDCADA- Version 3.1
Copyright (C) 1987-1992. Pamela J.. Schwab. All rights reserved..
Company Name: CASTLES CONSULTING ENGINEERS
Filename: B:\HARBOURI User. DN
Date;: 07--21-1994 Time; 08:37:11
VEGETATIVE CHANNEL #2 CALCULATIONS FOR 10-YEAR, 24--HOUR STORM.
Storm: 6.55 inches, 10 year-24 hour, SCS Type III
Hydrograph Convolution Interval. 0.1 hr
NON -POND STRUCTURE INPUT/OUTPUT TABLE
J1, B1, S1
OCEAN HEARBOUR
Drainage Area from J]., 81, S1, SWS(s)1: 3.6 acres
Total Contributing Drainage Area; 3.6 acres
f
MATERIAL. BERMUDA GRASS
Trapezoidal Vegetated Channel
Limiting Variable: Velocity = 8.000 fps
Design Bottom
Discharge Width
ZLeft ZRight
Slope
„
(efs) (ft')
( o)
3.89 4.0
3.0:1 3.0:1
5.0
Top Manning's
Hydraulic
Froude
Retardance
Depth Velocity
Width N
Radius
Number
Class
(ft) (fps)
(ft)
Stability B
0.76 0.81
8.6 0.273
0.542
0.19
Capacity B
0.76 0.81
8.6 0.273
0.542
0.19
w/ Freeboard + B
0.76
8.6
Runoff
Peak
Volume
Discharge
(ac--f't)
(cJfs)
IN/OUT 0.66
3.89
�K**�caK*�K�:*�Ic**��**�K�K�k�K��c%K*=K%K�Ic:K>KKK%K*=K�K�c>K=K>K�Ic�K>K>K�Ic�K�KaK�F:>K�c?K�c�K:K�K>K�*�k�c*�:aK%k�**:K*:K*�c=K**�K�K:K:M:::►�

A
CIVIL SOFTWARE DESIGN
SEDCAD+ Version 3
11
VEGETATIVE CHANNEL #3 CALCULATIONS FOR 10-YEAR, 24-HOUR STORM
by
Name: DN
Company Name: CASTLES CONSULTING ENGINEERS
File Name: B.-\HARBOUR
Date; 07--21~-1994
&

Civil Software Design -•- SEDCAD+ Version 3.1
Copyright (C) 1987-1992. Pamela J. Schwab. All rights reserved.
Company Name: CASTLES CONSULTING ENGINEERS
Filename: B:\HARBOUR User; DN
Date: 07-?1-1994 Time: 08:36:44
VEGETATIVE CHANNEL #3 CALCULATIONS FOR 10-YEAR, 24-HOUR STORM
Storm: 6.55 inches, 10 year-24 hour, SCS Type III
Hydrograph Convolution Interval: 0.1 hr
- m SUBWATERSHED/STRUCTUREINPUT/OUTPUT TABLE
-Hydrology-
Base-
Runoff
Peak
JBS
SWS
Area CN
UHS Tc
K X
Flow
Volume
Discharge
(ac)
(hrs)
(hrs)
(cfs)
(ac-ft)
(cfs)
111
1
1.22 60
M 0.167
0.000 0.000
0.0
0.23
1.60
Type:
Vegetated
Channel
Label. OCEAN
HARBOUR
111
Structure
1.22
0.23
----------------
1.11
.___________________-__________w________-_____-____________-__-_..
Total IN/OUT
1.22
0.23
1.60

Civil Software Design --- SEDCAD+ Version 3.1
Copyright (C) 1987-1992. Pamela J. Schwab. All rights reserved,.
Company Name: CASTLES CONSULTING ENGINEERS
Filename: B:\HARBOUR User: DN
Data: 07--21--1994 Time: 08:36:44
VEGETATIVE CHANNEL #3 CALCULATIONS FOR 10--YEAR, 24-HOUR STORM
Storm: 6..55 inches, 10 year•-24 hour, SCS Type III
Hydrograph Convolution Interval: 0.1 hr
NON -POND STRUCTURE INPUT/OUTPUT TABLE
J.I. , B1 ; S1
OCEAN HARBOUR
Drainage Area from J1, B1, S1, SWS(s)1: 1.2 acres,
Total Contributing Drainage Area: 1.2 acres
MATERIAL: BERMUDA GRASS
Trapezoidal Vegetated Channel
Limiting Variable: Velocity - 8.000 fps
Design Bottom
Discharge Width ZLeft ZRight
Slope
(cfs) (ft)
00
1.60 2.0 3.0:1 3.0:1
5.0
Top Manning's
Hydraulic
Froude
Retardance
Depth Velocity Width N
Radius
Number
Class
(ft) (fps) (ft)
Stability B
0.66 0.61 5.9 0.310
0.424
0.16
Capacity B
0.66 0.61 5.9 0.310
0.424
0.16
w./ Freeboard + B
0.66 .5.9
Runoff Peak
Volume Discharge
(ac-ft) (Cfs)
.IN/OUT 0.23 1.60
&

State of North Carolina
Department of Environment, Health, and Natural Resources
Wilmington Regional Office
James B. Hunt, Jr., Governor DIVISION OF ENVIRONMENTAL MANAGEMENT
Jonathan B. Howes, Secretary
July 8, 1994
Mr. Robert L. Castles, Jr., P.B.
Castles Consulting Engineers, Inc.
2411 Oak Street, Suite 304
Myrtle Beach, South Carolina 29577
Subject: ADDITIONAL INFORMATION
Stormwater Project No. 931204
Ocean Harbour Estates
Brunswick County
Dear Mr. Castles:
Bob Jamieson
Regional Manager
The Wilmington Regional Office received a Stormwater Submittal for the Ocean Harbour Estates
on July 6, 1994. A preliminary review of that information has determined that the submittal for the
subject project is not complete. The following information is needed to continue the stormwater review:
1. An investigation of your site by the Regional Soil Scientist supports your claim of the depth
of the water table. This information will be added to the file, in lieu of a formal soils
report which has not been provided.
/2. In regards to the 50 foot overflow swales; regardless of whether there will or will not be
an overflow, the swale must be provided in order to meet the infiltration requirements of
the State. The project will not be approved without an indication as to where the swale is
located and providing a cross-section. The same applies to Lot 11 overflow. Please label
the areas as overflows on the plans and provide a detail of the overflow swales. Please see
the attached regulations, highlighted. The contours on sheet 1 do not extend into the side
lot area of Lot 11. I cannot determine the nature of the existing topography in order to
check the erosive velocity of the overflow.
/3. My plans do not indicate the cul-de-sac radius. Please tell me where on the plans the radius
is noted.
1`0 Q�
127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 0 Telephone [phone] • Fax [phone]
An Equal Opportunity Affirmative Action Employer

Mr. Castles
July 8, 1994
Stormwater Project No. 931204
-----------------------------------------
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 August 8, 1994, or the submittal will
be returned as incomplete.
If you have any questions concerning this matter please feel free to call me at [phone].
Sincerely,
4c'r� AA"�
Ms. Linda Lewis
Environmental Engineer
DAlarl: S:\WQS\STORMWATIADDINFO\931204.JUL
cc: (2) Linda Lewis
Central Files

EHNR - EA '1R0,`'MENTAL :11,.1NAGE;I[ENT T15A: 02H .1000
(4) Alternatives are available if the control measures fail and will be required when the Director
determines that the system has failed;
No more than five projects utilizing the same innovative control measure will be approved until the
technology is proven over a time frame to be determined on a case -by -case basis. These five projects
will include projects approved since November 1, 1986 according to the provisions of 15A NCAC 2H
.0408.
(e) Design Criteria for Development Draining to Outstanding Resource Raters. Stormwater control
requirements to protect coastal waters classified as Outstanding Resource `Paters (ORW) pursuant to
15A NCAC 2B .0216 shall be determined in the process to reclassify the waters as ORW. After the
Commission has received a request to classify Class SA waters as ORW and given permission to the
Director to schedule a public hearing to consider reclassification and until such time as specific storm -
water design criteria become effective, only development which meets the requirements of Paragraph
(a) (2), (5) or (6) will be approved within 575 feet of mean high water of these waters.
(f) Design Criteria for Development Draining Directly to Class SA Waters.
(1) Direct outlet channels or pipes to SA waters are prohibited unless permitted in accordance with
15A NCAC 2H .0126.
(2) Infiltration control systems must be designed to control the runoff from all impervious surfaces
generated by one and one-half inches of rainfall. The size of the system must take into account
the runoff from any pervious surfaces draining to the system.
,(3) Runoff in excess of the design volume must flow overland through a vegetative filter with a
minimum width of 50 feet measured from mean high water of SA waters;
(g) Design Criteria For Development Not Draining to SA Raters.
(1) Infiltration control systems must be designed to control the runoff' from all impervious surfaces
generated by one inch of rainfall. The size of the system must take into account the runoff from
any pervious surfaces draining to the system;
(2) Vet detention ponds must be designed according to methods approved by the Director for 85
percent removal of total suspended solids in the permanent pool and storage of runoff from a
one inch rainfall from the site above the permanent pool;
(3) Vegetative filters are required for the over -flow and discharge of all stormwater %vct detention
ponds. These filters shall be at least 30 feet in length;
(4) Additional control measures may be required on a case -by -case basis to protect high quality
waters or specific water uses.
(h) Infiltration System Requirements. Infiltration systems may be designed to provide infiltration of
the entire design rainfall volume required for a site or a series of successive systems may be utilized.
Infiltration may also be used to pretreat runoff prior to disposal in a vet detention ponds. The fol-
lowing are requirements:
(1) Infiltration systems shall be a minimum of 30 feet from surface waters and 50 feet from Class
SA waters;
(2) Infiltration systems shall be a muumum distance of 100 feet from water supply wells;
(3) The bottom of infiltration systems shall be a minimum of 2. feet above the seasonal hiJm water
table;
(4) Infiltration systems must be designed such that runoff iin excess of the design volume by-passes
the system and does not flush pollutants througli the system;
(5) Infiltration systems must be designed to completely draw down io pre -storm levels within fix-c
days and a hydrogeologic evaluation may be required to determine whether the system can draw
down in five days;
(6) Soils must have a minimum hydraulic conductivity of 0.52 inches per hour to be suitable for
infiltration;
(7) Infiltration systems must not be sited on or in fill material;
(8) Infiltration systems must have an obscrvation.well to provide ready inspection of the system;
(9) If runoff is directed to infiltration systems during construction of the project, the system must
be restored to design► specifications after the project is complete and the entire drainage area is
stabilized.
(i) Vet Detention Pond Requirements. These practices can be used as a primanv treatment device
or as a secondary device following an infiltration system. Wet detention ponds shall be designed for a
specific pollutant removal according to modeling techniques approved by the Director. Specific re-
quirements for these systems are as follows:
(1) the design storage volume shall be above the permanent pool;
,VORTH CAROU. .4 AD.1 LYISTR: f TIT-T CODE 02122190 Page 3

F_IIA'R - F,\'i-'IROA'.-II ,N'TAI_ ,11AAAGL-.IIF-A'T T15A: 02H .1000
(2) The discharge rate from these systems following the one inch rainfall design storm shall be such
that the runoff does not draw down to the permanent pool level in less than two days and that
the pond is drawn down to the permanent pool level within at least five days;
(3) The mean depth shall be a minimum of three feet;
(4) The inlet structure must be designed to minimize turbulence using baffles or other appropriate
design features;
(5) Pretreatment of the runoff by the use of infiltration swales is encouraged to minimize sedimen-
tation and eutrophication of the detention pond.
Vegetative Filter Requirements. Vegetative filters shall be used as a non-structural method for
providing additional infiltration, filtering of pollutants and minimizing stormwater impacts. Require-
rients for these filters are as follows:
1-(1) A distribution device such as a swale shall be used to provide even distribution of runoff over
the length of the vegetative filter;
t(2) The slope and width of the vegetative filter shall be determined so as to provide a non-crosiyc
velocity of flow -through the filter for a 10-}•ear, 24-hour storm with a 10-Fear, 1-hour intensit%"
and the portion of the filter representing the minimum filter width specified in ParaP-aphs (f)
and (g) of this Rule shall have a slope of five percent or less;
(3) Vegetation in the filter may be natural vegetation, grasses or artificially- planted wetland vegc-
tation appropriate for the site characteristics;
(k) Operation and maintenance plans. An operation and maintenance plan or manual shall be pro-
vided by the developer for stormwater systems, indicating what operation and maintenance actions are
needed, what specific quantitative criteria will be used for determining «lien those actions are to be
taken, and who is responsible for those actions prior to approval of the development by the Division.
The plan must clearly indicate the steps that «will be taken and who will be responsible for restoring a
stormwater system to design specifications if a failure occurs and will include an acknowledgement bythe responsible party. Development must be maintained consistent with the requirements in these
plans and modifications to these plans must be approved by the Division.
(1) System Design. Stormivater systems must be designed by a North Carolina registered professional
with qualifications appropriate for the type of system required; design stormwater management systems:
these registered professionals arc defined as:
(1) professional engineers;
(2) landscape architects, to the extent that the General Statutes, Chapter 59A, alloy;-; and
(3) registered land surveyors, to the extent that the design represents incidental drainage within :+
subdivision, as provided in General Statute 89(C)-3(7).
Upon completion of construction, a registered professional appropriate for the type of stormwater
system designed must certify that the system was inspected during construction and was constructed in
substantial conformity with plans and specifications reviewed by the Division and complies with the
requirements of this Rule.
History Note: Statutory Authority G.S. 143-214.1; 143-215.1(d); 143-21J.3('7_)('l);
L•ff. January 1, 19k.
.1004 S'1'AITAI-IDE STOR\INVATER GUIDEL NES
The Division will periodically develop guidelines for the control of stormwater pollution from various
development practices and to protect specific water uses; these guidelines will be provided to requesting
individuals, institutions, local governments, or state,'federal agencies on request for use in developing
control stratc;ics for mitigating storm%vatcr pollution.
lusty Note: Statutory Authority G.S. 143-214.1; 143-215.3(a)(1 ); 143-21j.8.4'
r_ff. ✓anua,y 1, 1988.
A'ORTII C4ROI_INA ADMINISTRATIVE CODE 02127190 Page 4

M Is
D
JUL 0 8 1994
OCEAN HARBOUR ESTATES
DEM PRAJ # 231204- OPERATION AND MAINTENANCE PLAN ___
I, B. Darius Stanaland , do hereby state that as
the developer of the above referenced project, I will execute the
following maintenance plan on the project infiltration drainage
system or cause the same to be done by inclusion of this plan
into the homeowners' association documents.
Maintenance of the infiltration systems shall include but not be
limited to the following:
1. Periodic mowing of the grassed road shoulders.
2. Periodic removal of sediment and/or trash from the catch
basins as may be required to prevent the same from entering
the infiltration culverts.
3. Removal of any trash that may enter the infiltration
culverts.
4. General repairs to the catch basins, junction boxes,
culverts and overflows as may be necessary to maintain
the infiltration systems in good working order.
The above information is true and correct to the best of my
knowledge and belief and was provided by me under oath. (This
form must be signed by the financially responsible person if an
individual or his attorney -in -fact or if not an individual by an
officer, director, partner, or registered agent with authority to
execute instruments for the financially responsible person). I
agree to provide corrected information should there be any change
in the information provided herein.
B Darius Stanaland
Type or print name
Signature
President
Title of Authority
Date
a Notary Public of the County
of Brunswick State of North Carolina, hereby
certify that B. Darius Stanaland appeared personally
before me this day and being duly sworn acknowledged that the
above form was executed by him. y
'! Witness my hand and notarial seal, this �'lday of
14• „Tt1Y:iii.
Aw D*a'
Notdry
My commission expires k J

awwoftaftft
armVe
Thomas Realty
Linda Lewis,
N.C. Department of Environment and
Health and Natural Resources,
127 Cardinal Drive Extension,
Wilmington,
North Carolina, 28405 - 3845.
July 7, 1994
Dear Ms. Lewis,
JUL" U 81994 !�
Enclosed please find the signed original "Operation and Maintenance Plan"
for Ocean Harbour Estates.
A copy is being sent to Robert Castles of Castles Consulting Engineering
Inc., at 2411 Oak Street in Myrtle Beach.
Sincerely,
Nester Stanaland
p E C E i 1
D
JUL 0 8 1994
%EM
525 Sea Mountain Highway / North Myrtle Beach, South Carolina 29582 / Telephone [phone]
Each Office Is Independently Owned And Operated

Castles
onsumno
EnglneePS, InC.
June 30, 1994
North Carolina Department of Environmental,
Health, and Natural Resources
127 Cardinal Drive Extension
Wilmington, NC 28405-3845
Attention: Ms. Linda Lewis
Re: Ocean Harbour Estates
Dear Ms. Lewis:
JUL u b 1994
T 0 it' ;Nli V ivl! T ER
JUL 0 6 1994
DEM
p$pf 931 ZO4-
Per the review comments form your office, we offer the following
additional information.
1. From the attached sheet, two borings were made to a depth of
8 feet. The existing grade on each of these locations was
elevation 29.0 and the borings terminated at elevation 21.0.
The seasonal water table was not observed in either of these
borings to the termination depth. The soils encountered
were Wando soils and permeability tests resulted in perc
rates of around 40 inches per hour.
2&3. Please note that there will be no overflow from the drainage
systems as a result of the entire 10 year storm event or the
first 1 1/2" of runoff from larger storms. The overflow
designs have been incorporated into the system to provide
emergency relief of the runoff above the first 1 1/2" in
larger storm events. During these situations, junction box
#3 will overflow and sheetflow partially along the side of
lot number 30 and partially along the shoulder of Ocean
Harbour Drive. The overflow from lot number 11 will sheet
flow along the existing contours of the side yard in a
proposed grassed state.
4. A signed and notarized Operation and Maintenance plan will
be forthcoming from the developer.
5. Please see sheet Cl attached for radius of the cul-de-sac.
6_ The first 1 1/2" of runoff will be permanently retained by
the drainage systems as designed.
7. There are no water wells located on or adjacent to this
site.
ENGINEERING / LAND PLANNING / SURVEYING
Founders Centre, Suite 304
2411 N. Oak Street / Myrtle Beach, SC 29577 / 803-448-0910 / Fax: [phone]

8. Please see sheets 1 and 5 for the observation well locations
and details.
We appreciate your assistance in the review of this project.
If you have any questions, please do not hesitate to contact
US.
Sincerely,
)-� " - F, - Q:,- r-.
Braxton E. Lewis III
Engineering Designer
BEL/smg .
enclosures

aaw
State of North Carolina
Department of Environment, health, and Natural resources
Wilmington Regional Office
James B'Hunt, Jr., Governor DIVISION OF ENVIRONMENTAL MANAGEMENT Bob Jamieson
Jonathan B. Howes, Secretary Regional Manager
June 17, 1994
Mr. Robert L. Castles, Jr., P.E.
Castles Consulting Engineers, Inc.
2411 Oak Street, Suite 304
Myrtle -Beach, South Carolina 29577
Subject: ADDITIONAL INFORMATION
Stormwater Project No. 931204 Revised
Ocean Harbour Estates
Brunswick County
Dear Mr. Castles:
The Wilmington Regional Office received a revised Stormwater Submittal for Ocean Harbour
Estates on June 9, 1994. A preliminary review of that information has determined that the submittal for
the subject project is not complete. The following information is needed to continue the stormwater
review:
Ck �� • 1. Please provide a copy of the soils report which must include boring locations, soil types,
X, ' seasonal high water table elevations, and permeability recommendations. Without this
t rya �'X� information, I am unable to verify the 2' minimum separation between the bottom of the
rpl( �h �� �� A trench and the seasonal high water table. Based on the information you provide, it appears
;ny c that the bottom of the lowest trench is roughly elevation 23.5. This will require the water
�o table to be at least elevation 21.5, or 5.5 feet deep. Reporting that the water table is > 5'
�j 'V01�Q is insufficient evidence to support the conclusion that all the systems are maintaining the
2' separation.
�QS o1P
2. The overflow from all systems must pass through 50' vegetated filters prior to leaving the
A site. CBl-JB3 system overflow leaves the site prior to passing through 50' of vegetated
4� 1 rteO01" filter. Please show the 50' vegetated filter location and provide a detail. .
j� to 3. Please show the vegetated filter overflow path along Lot 11 in contour, and provide a
oak" 2(0 detail.
4. Please provide a signed and notarized Operation and Maintenance plan for maintenance
of the infiltration trenches.
127 Cardinal Drive Extension, Wilmington, N.C. 28405-3945 • Telephone [phone] • Fax [phone]
An Equal Opportunity Affirmative Action Employer

Mr. Castles
June 17, 1994
Stormwater Project No. 931204 Revised
-----------------------------------------
�n
Nvk 05. Please provide a cul-de-sac detail, or note the radius on the plans.
6. Please note that computation of the required storage volume is based on 1-1/2" of runoff,
not rainfall, from all surfaces that are directed to the infiltration trench due to the SA
classification of the Waterway. The normal procedure for determining storage volume does
not take into account the infiltration occuring during the storm event, however, the design
approach makes sense and pending the review of the soils report, may be able to be
certified as infiltration vs. innovative. This Office is mainly concerned with maintenance
of the system to keep the volume that you are providing available so that the first 1-1/2"
is infiltrated.
No e/ IX 7. Please locate any water supply wells.
S. Please provide observation wells and detail for each system.
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 15, 1994, or the submittal will be
returned as incomplete.
If you have any questions concerning this matter please feel fare to call me at [phone].
Sincerely,
Ms. Linda Lewis
Environmental Engineer
DA/arl: S:\WQS\STORMWAT\ADDINFO\931204.JUN
cc: (2) Linda Lewis
Central Files

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ST��AiER
0) k G k 0 W L
u� JUN 0 9 1994
DEM
OCEAN HARBOUR ESTATES � �3ag
SEDIMENT AND EROSION CONTROL NARRATIVE
WITH
STORM WATER MANAGEMENT NARRATIVE AND CALCULATIONS
Owner: Ocean Harbour Estates, Inc.
1157 River Road
Calabash, NC 28467
Engineer: Castles Consulting Engineers, Inc.
2411.Oak St., Suite #304
Myrtle Beach, SC 29577.
Purpose: To construct a 38 lot subdivision on 24.92 acres of
land in Brunswick County, NC. The minimum lot size for
this development will be one-third acre. Infra-
structure for this development will include paved
streets with associated drainage and a public water
supply system.
Site Description:
The site has rolling topography with slopes generally
2.0 to 6.0 %. The site is now covered moderate to
heavy with woody vegetation, predominantly pines.
There is no evidence of significant erosion under pre-
sent conditions.
Adjacent Property:
Soils:
The adjacent property is predominantly upland forest
except for one small parcel located along the northeast
property line which is developed as a golf course
fairway. There is no appreciable offsite drainage
directed toward this site.
The predominate soil on this site is Wando and classi-
fied in Hydrologic Soil Group "A" by the US Department
of Agriculture's Soil Conservation Service. Wando
soils are considered excessively drained soils with
permeability rates of 6-20 inches/hour. On site sub-
surface investigation confirmed the presence of these
soils.and percolation tests yielded permeabilities in
excess of 200 inches/hour.

The subsurface material to 99 inches deep is "strong
brown fine sand in the upper part and yellow fine sand
in the lower part".
Due to the rapid permeability of the subsoil that will
be exposed during the clearing and grading operations,
it is anticipated that there will be no problems as-
sociated with wetness or high runoff following signifi-
cant rainfall events. No ground water problem is ex-
pected. The rapidly permeable soils will make vegeta-
tion somewhat difficult to establish. Large quantities
of fertilizer, particularly nitrogen, will be required
to establish and maintain ground cover.
Planned Erosion and Sedimentation Control Practices:
1. Temporary gravel construction entrance/exit.
Two temporary gravel construction entrances will be
installed near the northeast and northwest property
corners. During periods of wet weather, washing
vehicle tires in these locations may be required.
The entrances shall be graded so that all runoff
will be directed toward an inlet protection device.
2. Fabric drop inlet protection.
Temporary fabric drop inlet protection shall be placed
at each catch basin located in the project.
3. Temporary sediment trap.
A small sediment trap will be constructed in the
existing drainage way located approximately midway of
the southwestern property line. Approximately 2
acres of disturbed area will drain into this trap (see
calculations).
4. Outlet stabilization structure.
A rip rap apron will be located on the outlet of the
culvert crossing located at the South Gate and Harbour
Watch Drive intersection. This outlet protection de-
vice will serve as an.energy dissipater to reduce scour
(see calculations).

5. Permanent Seeding.
All areas between the curbing and right of way shall, be
permanently seeded.
6. Grass -lined channel.
The existing channel located at the Harbour Watch and
South Gate intersection will be stabilized with
temporary straw -net liner and grassing.
7. Sediment fence.
A sediment fence will be installed along a portion of
Harbour Watch Drive to prevent sediment from leaving
the right of way.
8. Dust control is not expected to be a problem on this site.
However, should excessive dust be generated, it will
be controlled by sprinkling.
Construction Schedule
1. Obtain plan approval and other applicable permits
2. Survey and flag the limits of construction
3. Attend preconstruction conference a minimum of one week
prior to beginning construction
4. Clear and install temporary gravel construction entrances
5. Install temporary sediment trap
6. Complete site clearing
7. Install sediment fence
B. Rough grade site, stockpile topsoil, construct drainage
system and install fabric drop inlet protection on all catch
basins
9. Install water line and permanently vegetate and mulch the
offsite easements
10. Install curb and gutter roadway base material, finish
Trading road right of ways and permanently seed road
shoulders.
11. Install rip -rap bank protection and outlet stabilization on
culvert at South Gate and Harbour Watch intersection

12. Install grass and straw -net lining on existing channel.
13. All erosion and sediment control practices will be inspected
weekly and after rainfall events. Needed repairs will be
made immediately
14. After site is stabilized, remove all temporary measures and
install vegetation on disturbed areas
15. Estimated time before final stabilization--4 months
Maintenance Plan
1. All erosion and sediment control practices shall be in-
spected and checked for stability after every runoff -pro-
ducing rainfall but never less than once per week. All
required repairs will be made immediately.
2. Sediment shall be removed from the sediment trap and check
dams when the storage capacity has been approximately 50%
filled.
3. Sediment shall be removed from behind the sediment fence and
fabric inlet protection when it becomes 0.5 ft. deep at
the fence. The sediment fence and fabric drop inlet pro-
tection shall be repaired and/or replaced as necessary to
maintain the barrier.
4. All seeded areas will be fertilized, reseeded, mulched and
reshaped as necessary in accordance with the specifications
to maintain a healthy dense vegetative cover to the correct
lines and grades shown on the plans.

SECTION 2201
EROSION AND SEDIMENT CONTROL
PART I- SCOPE
1.01 WORK INCLUDED
A. The work included under this section consists of
furnishing all labor, equipment, and materials
necessary to prevent the transportation of disturbed
soil by means of air, water, gravity, or ice. This
work includes the installation, inspection, and
maintenance of sediment and erosion control structures
during land disturbing activities and the removal of
these structures upon stabilization of the disturbed
areas.
B. Definitions:
1. Gravel Construction Entrance: A temporary
sediment control consisting of a gravel driveway
or pad located at a point where vehicles enter and
exit the construction site.
2. Fabric Drop Inlet Protection: A temporary sedi-
ment barrier consisting of filter fabric installed
around the catch basins and between the catch
basin frames and grates.
3. Temporary Sediment Trap: A small temporary
ponding basin formed by an embankment or
excavation to capture sediment.
4. Outlet Stabilization Structure: A structure
designed to control erosion at the outlet of a
channel or conduit.
5. Permanent Seeding: The restabilization of
disturbed areas by seeding or sodding with grass.
6. Grass -lined Channel: A channel with vegetative
lining constructed to design cross-section and
grade for conveyance of runoff.
7. Sediment Fence:. A temporary sediment barrier
consisting of filter fabric stretched across and
attached to supporting posts, and entrenched.

B. Dust Control: A temporary control to prevent the
surface and air movement of dust.
PART II -MATERIALS
2.01 PRODUCTS
A. Sediment Fence
1. Synthetic filter. fabric shall be a pervious sheet
of propylene, nylon, polyester or ethylene yarn
certified by the manufacturer or supplier as
conforming to the following requirements:
Property
1. Tensile strength (lbs.)
2. Elongation (%)
3. Burst Strength (psi)
4. Puncture Strength (lbs.)
5. Trapezoidal Tear (lbs.)
6. Equiv. Opening Sieve Size
7. Permeability Coefficient
Acceptable Fabrics:
1. Amoco--Propex silt shop
2. Mirafi Environfence
3. Exxon 10OS-105S
Specification
Range
100-190
35 max.
200-300
70-80
50-65
30-700
0.009-0.2
(75 mm to 25 mm)
Test
Method
ASTM D-1682
ASTM D-1682
ASTM D-3786
ASTM D-751
ASTM D-1117
COECW-02215
Falling Head
2. Posts for sediment fences shall be either 4 inch
diameter wood or 1.33 pounds per linear foot
steel, at least 5 feet long. Steel posts shall
have projections for fastening wire to them.
3. Wire fence reinforcement for sediment fences using
standard strength filter cloth shall be a minimum
of 42 inches in height, a minimum of 14 gauge, and
shall have a maximum mesh spacing of 6 inches.
B. Rock
1. Rock for temporary sediment trap, and temporary
gravel construction entrance shall be MSHA size Na
2 (2 1/2" to 1") or AASHTO designation M43, size
No. 2 (2 1/2" to 1 1/2"). Use crushed stone.
2. Rock for outlet stabilization structure shall be
granite, angular in shape. Specific gravity of
the individual stones shall be at least 2.5.

C. Grass
1. Permanent Seeding --Grass seed shall be free from
noxious weed seeds and recleaned. Seed shall be
recent Grade A crop treated with appropriate
fungicide at time of mixing and delivered to the
site in sealed containers with dealer's guaranteed
analysis.
Proportion by weight:
62% Rye Grass
21% Carpet Grass
17% Bermuda Grass
2. Hydroseed--Hydroseed slurry mixture shall be:
Wood Fiber Mulch: 1200 lbs/acre
Carpet grass: 50 lbs/acre
Rye grass: 150 lbs/acre
Bermuda grass: 40 lbs/acre
10/10/10 Fertilizer: 400 lbs/acre
PART III- WORKMANSHIP
3.01 INSTALLATION
A. Temporary gravel construction entrance
1. Clear the entrance and exit area of all
vegetation, roots, and other objectionable
material and properly grade it.
2. Place the gravel to the specific grade and
dimensions shown on the plans, and smooth it.
3. Provide drainage to carry water to a sediment trap
or other suitable outlet.
4. Use geotextile fabrics because they improve
stability of the foundation in locations subject
to seepage or high water table.
5. Maintain the gravel pad in a condition to prevent
mud or sediment from leaving the construction
site. This may require periodic topdressing with
2-inch stone. After each rainfall, inspect any
structure used to trap sediment and clean it out
as necessary. Immediately remove all
objectionable materials spilled, washed, or
tracked onto public roadways.

B. Fabric drop inlet protection
1. Excavate around catch basins to leave a 24 inch
projection above grade.
2. Install filter fabric completely around the catch
basins and between the catch basin frame and
grates.
C. Outlet stabilization structure:
1. Ensure that the subgrade for the filter and riprap
follows the required lines and grades shown in the
plan. Compact any fill required in the subgrade to
the density of the surrounding undisturbed
material. Low areas in the subgrade on undisturbed
soil may also be filled by increasing
the rip -rap thickness.
2. The riprap and gravel filter must conform to the
specified grading limits shown on the plans.
3. Filter cloth, when used, must meet design
requirements and be properly protected from
punching or tearing during installation. Repair
any damage by removing the riprap and placing
another piece of filter cloth over the damaged
Area. All connecting joints should overlap a
minimum of 1 ft. If the damage is extensive,
replace the entire filter cloth.
4. Riprap may be placed by equipment, but take care
to avoid damaging the filter.
5. The minimum thickness of the riprap should be 1.5
times the maximum stone diameter.
6. Riprap may be field stone or rough quarry stone.
It should be hard, angular, highly weather -
resistant and well graded.
7. Construct the apron on zero grade with no overfall
at the end. Make the top of the riprap at the
downstream end level with the receiving area or
slightly below it.
B. Ensure that the apron is properly aligned with the
receiving stream and preferably straight throughout
its length. If a curve is needed to fit site
conditions, place it in the upper section of the
apron.

9. Immediately after construction, stabilize all
disturbed areas with vegetation.
10. Inspect riprap outlet structures after heavy rains
to see if any erosion around or below the riprap
has taken place or if stones have been dislodged.
Immediately make all needed repairs to prevent
further damage.
D. Grass -lined channel
1. Remove all trees, brush, stumps, and other
objectionable material from the foundation area and
dispose of properly.
2. Excavate the channel and shape it to neat lines and
dimensions shown on the plans plus a- 0.2 ft.
overcut around the channel perimeter to allow for
bulking during seedbed preparations and sod
buildup.
3. Remove and properly dispose of all excess soil so
that surface water may enter the channel freely.
4. Apply lime, fertilizer and seed to the channel and
adjoining areas in accordance with the vegetation
plan.
5. Spread straw mulch at the rate of 1001b/1000 sq.
ft.
6. Hold mulch in place immediately after spreading
with netting installed as shown.
7. Start laying the net from the top of the upstream
end of the channel and unroll it down grade. Do
not stretch netting.
8. Bury the upslope end and staple the net every 12"
across the top end, every 3 ft. around the edges
and across the net so that the straw is held
closely against the soil, however, do not stretch
the netting when stapling.
9. Netting strips should be joined together along the
sides with a 3" overlap and stapled together.
10. To join ends of strips, insert the new roll of net
in a trench as with upslope end and overlap it 18"
with the previously laid upper roll. Turn under 6"
of the 18" overlap and staple very 12" across the
end.

11. During the establishment period, check grass -lined
channels after every rainfall. After grass is
established, periodically check the channel; check
it after every heavy rainfall event. Immediately
make repairs. it is particularly important to
check the channel outlet and all road crossings for
bank stability and evidence of piping or scour
holes. Remove all significant sediment
accumulations to maintain the designed carrying
capacity. Keep the grass in healthy, vigorous
condition at all times, since it is the primary
erosion protection for the channel.
E. Sediment fences --Sheet flow applications
1. The ' height of a sediment fence shall be a minimum
of 15 inches and shall not exceed 18 inches.
2. Standard strength synthetic filter fabric shall be
in a continuous roll cut to the length of the
barrier to avoid the use of joints. When joints
are necessary, the fabric shall be spliced together
only at a stake, with a minimum 6 inch overlap, and
sealed securely.
3. The stakes shall be spaced a maximum of 3 feet
apart along the barrier and driven securely into
the ground a minimum of 8 inches.
4. A trench shall be excavated approximately 4 inches
wide and 4 inches deep along the line of stakes,
upslope from the barrier.
5. The filter material shall be stapled to the wooden
stakes, and 8 inches of the fabric shall be
extended into the trench. Heavy duty wire staples
at least 1/2 inch long shall be used. Filter
material shall not be stapled t®.trees.
6. The trench shall be backfilled and the soil com-
pacted over the filter material.
F. Hydroseeding
1. Use only equipment and materials specifically
designed for use in hydroseeding application.
2. Apply mixture to result in complete coverage of all
areas to receive seeding.
3. Insure all areas are properly fine graded and free
from rocks, debris, ridges and ruts before seeding.

4. Any areas seeded, before fine grading is completed
shall be re -seeded at no additional cost to the
Owner following correction of the conditions.

STORM WATER MANAGEMENT
NARRATIVE
Project Type: Low density with curb and gutter and exfiltration
system
Description: One of the motives for developing this storm water
management concept was to minimize the abrupt
grade changes that a swale system would require
for the driveways extending on to the residential
lots. Additionally, the developer would prefer to
minimize the number of trees which have to be
removed out of the right of ways behind the
curbing.
Beginning with this view of the project, we
designed the road profiles with curb and gutter
using a minimum road slope of 0.5 percent.
Designing the road grades with this criteria, low
points were established on the profiles in an
effort to minimize the curb depth below the
existing grades. Having established the low
points in the roadways, we delineated the
drainage areas and computed their respective
hydrologic parameters using the SCS Unit
Hydrograph Method.
Onsite subsurface investigation confirmed the
presence of Wando Soils and percolation tests
yielded permeabilities in excess of 200
inches/hour. The water table was not reached in
these tests which were conducted to a depth
of 5 feet. (See "Soils" on page 1 of this
report).
From the attached plan "Drainage Areas", the site
has been subdivided into 7 catchments. Each
catchment was then summarized for percentages of
pervious and impervious surfaces based on the
following land use categories.
Land Use Cn
Streets 98
* Roofs and Driveways 98
Lawns and open spaces 35
* Maximum impervious surface per lot = 5305 sq.ft.

After determining the weighted Cn number of each
catchment, a time of concentration was
calculated based on the proposed grades and
routes of runoff. (A summary of the catchment
data and runoff hydrographs for the 10 year
storm is contained in Table #1.)
Having determined the roadway low points and the
10 year peak runoff associated with each of the
drainage areas, the following principles were used
to design the drainage exfiltration system.
1. Following the conveyance of storm water runoff along
the curb and gutter, the runoff is intercepted by catch
basins which discharge to a subsurface exfiltration
system.
2. The.exfiltration system is typically composed of a 24
inch perforated pipe encased in a one foot washed
gravel envelope which in turn is wrapped in a permeable
geotech fabric. (See detail on sheet 5 of the plans.)
3. A typical length of this "exfiltration trench" has the
capacity to (1) percolate storm water into the ground
along the surface area of its sides and bottom and (2)
to store a volume of storm water equivalent to the pipe
volume and void ratio of the surrounding gravel
envelope.
4. The gravel envelope serves a two fold purpose to the
performance of the "exfiltration trench". First, it
enlarges the surface area of the trench yielding a
greater discharge per linear foot of pipe installed and
secondly, it provides a filter media to remove
impurities from the runoff.
5. The following method was used to size the required
length of exfiltration trench for each drainage area.
a. From Table #1, the peak runoff for a particular
drainage area was obtained.
b. Catch basins and junction boxes were networked
together with lengths of exfiltration trench.
Typically, the lengths of "trench" were connected
to boxes located in the drainage area under
study.
C. Each drainage area's cumulative length of
"trench" was then analyzed to obtained the total
perc surface area of the envelope and the total
permeability of this surface area (based on the
soil permeability).

d. Having determined the total perc rate of a
drainage area's trench length, this pert rate was
then plotted along the X axis of a graph of the
drainage area's hydrograph.
e. This perc rate as plotted on the hydrograph,
therefore, represents that rate of runoff which
can be percolated into the ground surrounding the
sides and bottom.of the trench.
f. The area of the hydrograph remaining under the
curve and above the perc rate line represents the
volume of water from the hydrograph that can not
be percolated out of the trench during the storm
peak and therefore would have to be stored in the
trench system until complete percolation takes
place.
g. The volume of runof f below the curve and above the
perk rate line is then determined as follows:
1. From the X and Y axes of the graph, linear
interpolation is used to obtain an equivalent
flow in cubic feet per second per inch on the
graph and seconds per inch on the graph. By
multiplying these two values, we obtain a
volume in cubic feet per square inch on the
graph.
2. The area under the graph and above the perc
rate line is then calculated in square inches
and when multiplied by the conversion factor
of cubic feet per square inch, we obtain the
volume of runoff which must be stored in the
trench. This volume will typically be called
the "required storage".
h. Having determined the "required storage" for the
study area, the available storage is computed by
(1) calculating the volume in the 24" pipe, (2)
calculating the volume in the rock envelope (40%
void ratio) and (3) calculating the volume in
each catch basin or junction box which connects
the trench system.in the drainage area. The
cumulative total of these volumes yields the
'"available storage".
i. A comparison of the "available storage" to the
"required storage" should result in an adequate or
surplus volume in the system which is necessary to
prevent surcharging of the catch basins or pre-
mature release of storm water runoff out of the
system.

j . By way of trial and error each system of trench is
lengthened or shortened to produce the desired
results.
6. Additional features of the exfiltration system includes
the following:
a. Each catch basin and junction box will feature a
one foot deep sediment basin to allow sand and
dirt to be trapped in the basin before it enters
the perforated pipe.
b. Each catch basin and junction box will also
feature a one foot diameter hole cast in the
bottom and filled with gravel to allow for
automatic draining of the sediment basin at the
end of the storm and allowing easy removal -of
sediment.
7. Maintenance of the system will largely involve the
periodic cleaning of the sediment traps in both the
catch basins and junction boxes.
8. Emergency overflow for runoff from storms greater than
the designed frequency. The following considerations
have been included in this design for emergency
overflow conditions. (Please reference sheet 1 of
the plans.)
a. System of CB #1 - .7B #3
Emergency overflow of this system involves minor
ponding of the entrance to South Gate Drive where
the storm water will over top the curb and be
routed down an existing 270 linear foot swale in
the shoulder of Ocean Harbour Drive which dis-
charges to an existing pond at the rear of lot
#38.
b. System of CB #5- CB#11
Emergency overflow of this system will involve
surcharging or head water build up at the frame
And grate of CB #6 located on South Gate
Extension. South Gate Extension has a "downward
grade" toward South Gate Drive which in turn
slopes down to the intersection of South Gate
Drive and Harbour Watch Drive. During emergency
overflow conditions storm water will "back out,,
of the frame and grate at CB #6 and be conveyed
along the curb and gutter to the catch basins
located at the intersection of South Gate Drive
and Harbour Watch Drive. The emergency overflow
for the catch basins at this intersection is
described below.

C. System of CB #12 - CB #17
Emergency overflow of this system will occur at CB
#14. (See detail on right of Sheet 1.) A brick
weir will be installed in this catch basin to
isolate the exfiltration system from the 18" RCP
which outfalls to the existing channel between lot
numbers 6 and 7. This weir has been designed from
the catch basin bottom to 6 inches above the top
of the perforated pipe in the exfiltration trench.
The weir at this elevation will allow complete
saturation of the exfiltration trench which is
necessary to produce the designed performance of
this system. During overflow conditions storm
water will "over top" the weir and be discharged
via the 18" pipe and down the grass lined channel.
The outlet of the 18" pipe will be equipped with
outlet stabilization, per the detail on Sheet 5,
which will prevent scouring of the grass lined
channel.
d. System of JB #18 - JB #20'
Emergency overflow of this system will involve
"surcharging" or head water build up until
overflow occurs out of the frame and grate of JB
#20. The frame and grate of this junction box
will have a grate with holes and since the grate
of this junction box is set 6 inches lower than
the other two boxes in this system, storm water
will overflow this grate and sheet flow down 400
feet of the side yard along. lot #11.
Stormwater Calculations:
The following nine pages comprise the calculations that were
performed in the design of this storm water management
system. Table #1 which follows, is a summary of the hydro -
graphs for each of the drainage areas. The remaining eight
pages describe the design of each portion of the exfiltra-
tion system. Each drainage area (i.e. HA1) has its sheet of
calculations along with a corresponding hydrograph which
graphically represents the performance and required storage
of each portion of the system.
Conclusion:
This drainage plan represents a somewhat innovative approach
to design of the "bow Density Development with Curb and
Gutter". In preparing this design, we have attempted
to exercise care in creating a project design that
would both fulfill our client's vision and comply with
the intent of the laws of North Carolina. The design
of the "exfiltration system" is based on sound
engineering principles with a conservative approach.
In the preceding calculations, a permeability of 40

inches per hour was used instead of a larger value
which our percolation tests yielded in the field.
Additionally, within each portion of the exfiltration
system there exists surplus storage above the volume
required and lastly, the emergency overflow from each
of these systems will provide a safe and adequate
discharge of storm water for events greater than the
design frequency. In conclusion we would also like to
note, that 100 percent of the 10 year events runoff
from the directly connected impervious surfaces will be
treated by this system.

Advanred Interconnected
Channel & Pond Routj/'o (adICPR Vcr
1.40)
Copyriqkt
1989^ Streamline
Tachnoloyies.
Inc.
���TABLEmrm
BASIN i`!AME
HA1
HD1
HC1
HD
HE1
NODE NAME
NA1
` NB1
NC1
ND1
NE1
UNlT HYDROGRAPH
UH484
�H4B4
U|1484
UH484
UH484
PEAKING FACTO�
484.
484.
484.
484.
484.
RAINFALL FILE
SCSIII
SC3III
SCSIII
SCSIlI
SCSIII
RAIN AMOUNT (in)
6.55
STORM DURATION (hrs)
24.00
6.55
24.00
6.55
6.55
6 55
21.00
24.00
24~00
AREA (ac)
1.22
3.61
4.10
2.59
2^ 08
CURVE NUMBER
60.00
59.00
61.00
56.00
55^00
DCIA (%)
0�
00
00
00
TC (mins)
10.00
,
20 00
,.oV
20.00
20
LAG TIME (h��>
'-'
^
�0 00
. 00
. 00
.0O
.00
00
BAST STATUS
ONSITE
ONSITE
ONSITE
ONSITE
ONS�TE
BASIN QMy (cfs) TMX
(hrs) VOL
(in) NOTES
KA1 2.52
12.27
2.29
HB1 6.10
12,31
2.20
HC! 7.57
12.33
2.38
HD1 3.78
12.31
1.93
HE! 3.45
12.27
1.84 DIRECT
RUNOFF
BASlN NAME
HE2
HE3
NODE NAME
NE2
NE3
UNIT HYDROGRAPH
UH484
UH484
PEAKING FACTOR
484.
484'
RAINFALL FILE
SCSlII
SCSIIl
RAIN AMOUNT (in)
6.55
6.55
STOR�� DURATIO� (hrs)
24.00
24,00
AREA (ac)
1.66
9.6e-.�
CURVE NUMBER
56.00
48.0("..,,
DCIA (%)
.00
.00
TC Wins)
15.00
8.00
LAG TIME (hrs}
.00
.00
BASIN STATUS
ONSITE
ONSITE
BASIN QMX <cfa> TMX
(hrs) VOL
(in) NOTES
1-1,E2 2.66
12.30
1^93 DIRECT
RUNOFF
HE3 11.05
12.27
1.26 DIRECT
RUNOFF

DRAINAGE AREA
HA1
Soil borings and perc tests have been performed on site to verify
soil type, depth of water table and permeability. Results are as
follows:
Soils: Wando--Hydrologic Soil Group A
Water table: > 5 feet
Permeability: 40 inches/hour
Calculations:
From the attached hydrograph and summary for Area HA1, the peak
discharge equals 2.52 cfs.
The plan.for area HA1 calls for installing 130 feet of 24 inch
Perforated pipe with a 1 foot gravel envelope.
Total perc surface of this envelop equals:
(4.0 feet + 4.0 feet + 4.0 feet)(130 feet) = 1560 sq.ft.
Permeability of soil equals:
40 inches/hour = 3.3 feet/hour = 0.0009 feet/sec.
Total permeability along 100 feet of gravel envelope equals:
0.0009 feet/sec. x 1560 sq.ft. = 1.4 cu.ft./sec.
From the attached hydrograph the 1.4 cu.ft./sec. perc rate is
Plotted leaving an area under the curve above this line as
the volume of storage required within this system.
Area under the curve = 0.341 sq.in.
1 sq.in on graph = 3241 cu.ft./sq.in.
Volume of storage required = 1105 cu.ft.
Volume of storage in system:
Volume in pipe = 130 ft. (3.1416) (1.0)2 = 408 cu.ft.
Volume in rock = 130 ft. ((4.0 ft.)
(4.0 ft.) - 3.1416 (1.0)2(0.4)
669 cu.ft.
Volume in catch basins = 3 (3 ft. x 3 ft. x 3 ft.) _
81 cu.. ft.
1158 Tuft.
Available storage - Required storage =
1158 cu.ft. - 1105 cu.ft. = 53 cu.ft. surplus

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DRAINAGE AREA
HB1
Soil borings and perc tests have been performed on site to verify
soil type, depth of water table and permeability. Results are as
follows:
Soils: Wando--Hydrologic Soil Group A
Water table: > 5 feet
Permeability: 40 inches/hour
Calculations:
From the attached hydrograph and summary for Area HB1, the peak
discharge equals 6.10 cfs.
The plan for area HA1 calls for installing 422 feet of 24 inch
perforated pipe with a 1 foot gravel envelope.
Total perc surface of this envelop equals:
(4.0 feet + 3.0 feet + 3.0 feet)(422 feet) = 4220 sq.ft.
Permeability of soil equals:
40 inches/hour = 3.3 feet/hour.= 0.0009 feet/sec.
Total permeability along 100 feet of gravel envelope equals:
0.0009 feet/sec. x 4220 sq.ft. = 3.8 cu.ft./sec.
From the attached hydrograph the 3.8 cu.ft./sec. perc rate is
Plotted leaving an area under the curve above this line as
the volume of storage required within this system.
Area under the curve = 0.326 sq.in.
1 sq.in on graph = 6483 cu.ft./sq.in.
Volume of storage required = 2113 cu.ft.
Volume of storage in system:
Volume in pipe = 422 ft. (3.1416) (1.0)2 1326 cu.ft.
Volume in rock = 422 ft. ((4.0 ft.)
(3.0 ft.) - 3.1416 (1.0)2(0.4) _
1495 cu.ft.
Volume in catch basins = 6 (3 ft. x 3 ft. x 3 ft.) = 216 cu.ft.
3037 cu.ft.
Available storage - Required storage =
3037 cu.ft. - 2113 cu.ft. = 924 cu.ft. surplus

I
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41

DRAINAGE AREA
HC1
Soil borings and perc tests have been performed on site to verify
soil type, depth of water table and permeability. Results are as
follows:
Soils: Wando--Hydrolbgic Soil Group A
Water table: > 5 feet
Permeability: 40 inches/hour
Calculations:
From the attached hydrograph and summary for Area HC1, the peak
discharge equals 7.57 cfs.
The plan for area RAJ calls for installing 420 feet of 24 inch
perforated pipe with a 1 foot gravel envelope.
Total pert surface of this envelop equals:
(4.0 feet + 4.0 feet + 4.0 feet)(420 feet) = 5040 sq.ft.
Permeability of soil equals:
40 inches/hour = 3.3 feet/hour = 0.0009 feet/sec.
Total permeability along 100 feet of gravel envelope equals:
0.0009 feet/sec. x 5040 sq.ft. = 4.5 cu.ft./sec.
From the attached hydrograph the 4.5 cu. f t. /sec. per. c rate is
Plotted leaving an area under the curve above this line as
the volume of storage required within this system.
Area under the curve = 0.465 sq.in.
1 sq.in on graph = 6483 cu.ft./sq.in.
Volume of storage required = 3015 cu.ft.
Volume of storage in system:
Volume in pipe = 420 ft. (3.1416) (1.0)2 = 1319 cu.ft.
Volume in rock = 420 ft. ((4.0 ft.)
(4.0 ft.) - 3.1416 (1.0)2(0.4) = 2160 cu.ft.
Volume in catch basins = 6 (3 ft. x 3 ft. x 3 ft.) = 162 cu.ft.
3641 cu.ft.
Available storage Required storage =
3641 cu.ft. - 3015 cu.ft. = 626 cu.ft. surplus

011
.till.
I
I
I

DRAINAGE AREA
HD1
Soil borings and perc tests have been performed on site.to verify
soil type, depth of water table and permeability. Results are as
follows:
Soils: Wando--Hydrologic Soil Group A
Water table: > 5 feet
Permeability: 40 inches/hour
Calculations:
From the attached hydrograph and summary for Area HD1, the peak
discharge equals 3.78 cfs.
The plan for area HA1 calls for installing 190 feet of 24 inch
perforated pipe with a 1 foot gravel envelope.
Total perc surface of this envelop equals:
(4.0 feet + 4.0 feet + 4.0 feet)(190 feet) = 2280 sq.ft.
Permeability of soil equals:
40 inches/hour = 3.3 feet/hour = 0.0009 feet/sec.
Total permeability along 100 feet of gravel envelope equals:
0.0009 feet/sec. x 2280 sq.ft. = 2.1 cu.ft./sec.
From the attached hydrograph the 2.1 cu.ft./sec. perc rate is
Plotted leaving an area under the curve above this line as
the volume of storage required within this system.
Area under the curve = 0.481 sq.in.
1 sq.in on graph = 3241 cu.ft./sq.in,
Volume of storage required = 1559 cu.ft.
Volume of storage in system:
Volume in pipe = 190 ft. (3.1416) (1.0)2 =
) 597 cu.ft.
Volume in rock = 190 ft. ((4.0 ft.)
(4.0 ft.) - 3.1416 (1.0)2(0.4) =
977 cu.ft.
Volume in catch basins = 3 (3 ft. x 3 ft. x 3 ft.) = 81 cu.ft.
1655 cu.ft.
Available storage - Required storage =
1655 cu.ft. - 1559 cu.ft. = .96 cu.ft. surplus

I
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CASTLES CONSULTING ENGINEERS, INC.
2411 Oak St. Suite 304
MYRTLE BEACH, SOUTH CAROLINA 29577
[phone]
FAX [phone]
To NC Dept. of Env. Health and Nat. Res.
127 Cardinal Drive Ext.
Wilmington, NC 28405-3845
[AVVIEn OCR 4 0 0 H@W0CT4Qd
DATE
June 7 1994
JOB NO.
ATTENTION
Greg Stutts
RE:
Ocean Harbour Estates
- em e.*j ( 'Rl Tell
WE ARE SENDING YOU XI Attached ❑ Under separate cover via -_ th&40 lD,pfffg ITems
❑ Shop drawings ❑ Prints KO Plans ❑ Samples ❑ Specifications
❑ Copy of letter ❑ Change order X Report
COPIES
DATE
NO.
DESCRIPTION
3
6 6 94
Construction Plans
1
6 6 94
Sediment Erosion'Control and Storm Water Report
3
6 6 94
Drainage Areas TifilnW, . Trn
3 f Zv4-
THESE ARE TRANSMITTED as checked below:
N For approval
❑ For your use
❑ As requested
❑ For review and comment
❑ FORBIDS DUE
❑ Approved as submitted
❑ Approved as noted
❑ Returned for corrections
❑ Resubmit
❑ Submit
❑ Return
copies for approval
copies for distribution
corrected prints
19 ❑ PRINTS RETURNED AFTER LOAN TO US
REMARKS Dear Greg:
Attached please fine the submittal package for revisions to the
above referenced project previously permitted under Project #931204 Please
review the attached information and contact me with any comments you may
COPY TO
RECYCLED PAPER:
Contents: 40% Pre -Consumer • 10% Post -Consumer SIGNED:
if enclosures are not as noted, kindly notify us at once.