SW8060213_CURRENT PERMIT_20060314

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW
DOC TYPE
� CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
YYYYMMDD

W A TF9Q
C r
3
o �
March 14, 2006
Mr. Mark Evans, President
La Costa Development Corporation
PO Box 2294
Wilmington, NC 28402
Subject: Stormwater Permit No. SW8 060213
La Costa Bay
High Density Project
Onslow County
Dear Mr. Evans:
Michael F. Easley, Governor
William G. Ross Jr.. secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.F. Director
Division of Water Quality
The Wilmington Regional Office received a complete Stormwater Management Permit
Application for La Costa Bay on March 13, 2006. 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 Permit No. SW8 060213 dated March
14, 2006, for the construction of the subject project.
This permit shall be effective from the date of issuance until March 14, 2016, 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 sixty (60) 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 Linda Lewis, or me at [phone].
Sincer ly,
Edward Beck
Regional Supervisor
Surface Water Protection Section
ENB/arl: S:IWQSISTORMWATIPERMIT1060213.mar06
cc: Richard Moore, P.E., McKim and Creed
Onslow County Building Inspections
Doug Huggett, DCM
Linda Lewis
Wilmington Regional Office
Central Files one
NotthCarolina
,llatumlly
North Carolina Division ofWater Quality 127 Cardinal Drive Extension Wilmington, \C 28405 Phone [phone] Customer Service
Wilmington Regional Office Intemet: %v%va•.nc%vatcrquality.org Fax [phone]
An Equal OpportunitylAifirmative Action Employer — 50% Recycled110% Post Consumer Paper

State Stormwater Management Systems
Permit No. SW8 060213
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
Mark Evans & La Costa Development Corporation
La Costa Bay
NCSR 1568, North Topsail Beach, Onslow County
FOR THE
construction, operation and maintenance of 2 underground infiltration trenches in
compliance with the provisions of 15A NCAC 2H .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 March 14, 2016, 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 in Section 1.6 on page 3 of this permit. The stormwater
controls have been designed to handle the runoff from 30,240 ft and 4,330 ft2
respectively, of impervious area. The infiltration trenches must be operated with
a 50' vegetated filter. Runoff from the 663 ft concrete pool deck area will sheet
flow across a minimum 30' wide grassed area.
3. The tract will be limited to the amount of built -upon area indicated on page 3 of
this permit, and per approved plans. No allotment of built=upon area has been
made for future development under this permit.
4. All stormwater collection and treatment systems must be located in either
dedicated common areas or recorded easements. The final plats for the project
will be recorded showing all such required easements, in accordance with the
approved plans.
5. The runoff from all built -upon area within the permitted drainage area of this
project must be directed into the permitted stormwater control system.
Page 2 of 7

State Stormwater Management Systems
Permit No.
SW8 060213
6. The
following design criteria have been provided
-
inthe infiltration trench and -
must
be maintained at design condition:
DB #1
DB#2
a.
Drainage Area, acres:
0.85
0.17
Onsite, ft2:
37,026
7,405
Offsite, ft2:
0
0
b.
Total Impervious Surfaces, ft2:
30,240
4,330
C.
Design Storm, inches:
1.5
1.5
d.
Trench Dimensions, L x W x H, ft:
154 x 40 x 1.5
40 x 25 x 1.5
e.
Perforated Pipe Diameter/Length:
12" 0l 1,272
12"0 / 180
f.
Bottom Elevation, FMSL:
5.5
5.5
g.
Bypass Weir Elevation, FMSL:
7.0
7.0
h.
Permitted Storage Volume, ft3:
4,295 '
684
i.
Type of Soil:
NeE
NeE
j.
Expected Infiltration Rate, in/hr:
9.6
9.6
k.
Seasonal High Water Table, FMSL:
3.50
3.50
1.
Time to Draw Down, hours:
<2
<2
M.
Receiving Stream/River Basin:
ICWW / White Oak
n.
Stream Index Number:
WOK02 19-39-(0.5)
o.
Classification of Water Body:
"SA;HQW"
II. SCHEDULE OF COMPLIANCE
1. The Stormwater management system shall be constructed in its entirety,
vegetated and operational for its intended use prior to the construction of any
built -upon surface.
2. During construction, erosion shall be kept to a minimum and any eroded areas of
the system will be repaired immediately.
3. 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 slopes and the vegetated filter.
d. Immediate repair of eroded areas.
e. Maintenance of all slopes in accordance with approved plans and
specifications.
f. Debris removal and unclogging of bypass structure, filter media, flow
spreader, catch basins, piping and vegetated filter.
g. A clear access path to the bypass structure must be available at all ti mes.
Page 3 of 7

State Stormwater Management Systems
Permit No. SW8 060213
- _.._..----"-- __. _.._. - - _ - - - -- - -
-4. __ _ 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.
5. The facilities shall be constructed as shown on the approved plans. 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.
6. 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. A
modification may be required for those deviations.
7. If the 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.
8. Access to the stormwater facilities shall be maintained via appropriate
easements at all times.
9. The permittee shall submit to the Director and shall have received approval for
revised plans, specifications, and calculations prior to construction, for any
modification to the approved plans, including, but not limited to, those listed
below:
a. Any revision to any item shown on the approved plans, including the
stormwater management measures, built -upon area, details, etc.
b. Project name change.
C. Transfer of ownership.
d. Redesign or addition to the approved amount of built -upon area or to the
drainage area.
e. Further subdivision, acquisition, lease or sale of all or part of the project
area. The project area is defined as all property owned by the permittee,
for which Sedimentation and Erosion Control Plan approval or a CAMA
Major permit was sought.
f. Filling in, altering, or piping of any vegetative conveyance shown on the
approved plan.
10. The permittee shall submit final site layout and grading plans for any permitted
future areas shown on the approved plans, prior to construction.
11. 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.
12. 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.
Page 4 of 7

State Stormwater Management Systems
Permit No. SW8 060213
-GENERAL-CONDITIONS-__—___--��-----
This permit is not transferable except after notice to and approval by the Director.
In the event of a change of ownership, or a name change, the permittee must
submit a formal permit transfer request to the Division of Water Quality,
accompanied by a completed name/ownership change form, documentation
from the parties involved, and other supporting materials as may be appropriate.
The approval of this request will be considered on its merits and may or may not
be approved. The permittee is responsible for compliance with all permit
conditions until such time as the Division approves the transfer request.
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) having 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 permittee grants DENR Staff permission to enter the property during normal
business hours for the purpose of inspecting all components of the permitted
stormwater management facility.
6. 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.
7. Unless specified elsewhere, permanent seeding requirements for the stormwater
control must follow the guidelines established in the North Carolina Erosion and
Sediment Control Planning and Design Manual.
8. Approved plans and specifications for this project are incorporated by reference
and are enforceable parts of the permit.
9. The permittee shall notify the Division any name, ownership or mailing address
changes within 30 days.
Permit issued this the 14th day of March 2006.
NORTHfCAROLINA�ENVIRONMENTAL MANAGEMENT COMMISSION
for`Alan W. Klimek, P.E., Director
Division of Water Quality
By Authority of the Environmental Management Commission
Page 5 of 7

State Stormwater Management Systems
Permit No. SW8 060213
La Costa Bay
Stormwater Permit No. SW8 060213
Onslow CountY
Designer's Certification
I, , as a duly registered in the
State of North Carolina, having been authorized to observe (periodically/ weekly/ full
time) the construction of the project,
(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 is included in the Certification.
Noted deviations from approved plans and specification:
Signature
Registration Number
Date
SEAL
Page 6 of 7

State Stormwater Management Systems
Permit No. SW8 060213
Certification -Requirements: ---- -- - - -�
.1. 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. All roof drains are located such that the runoff is directed into the system.
5. The bypass structure elevations are per the approved plan.
6. The bypass structure is located per the approved plans.
7. A Trash Rack is provided on the outlet/bypass structure.
8. All slopes are grassed with permanent vegetation.
9. Vegetated slopes are no steeper than 3:1.
10. The inlets are located per the approved plans and do not cause short-
circuiting of the system.
11. The permitted_ amounts of surface area and/or volume have been
provided.
12. All required design depths are provided.
13. All required parts of the system are provided.
14. The required system dimensions are provided per the approved plans.
CC' NCDENR-DWQ Regional Office
Onslow County Building Inspections
Page 7 of 7

a
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form gray be photocopied for use as an original
I. GENERAL INFORMATION:
1. Applicant's name (specify the name of the corporation, individual, etc. who owns the project):
La Costa Development Corp. _
2. Print Owners/Signing Official's name and title (the person legally responsible for facility and compliance):
Mark Evans, President
3. Mailing Address for person listed in item 2 above:
P.O. Box 2294
City: Wilmington State
Telephone Number: 910-328-1235
NC
Zip: 28402
4. Project Name (subdivision, facility, or establishment name - should be consistent with project name on
plans, specifications, letters, operation and maintenance agreements, etc.):
La Costa Bay
5. Location of Project (street address):
Approximately 3.2 miles north from where S.R. 1568 (New River Inlet Rd.) splits from Hwy. 210 in North
Topsail Beach, NC.
City: North Topsail Beach County: Onslow
6. Directions to project (from nearest major intersection):
Approximately 3.2 miles north from where S.R. 1568 (New River Inlet Rd.) intersects Hwy. 210 in North
Topsail Beach, NC.
7. Latitude: 34°30'45"N
Longitude: 77°22'40"W
8. Contact person who can answer questions about the project:
Name: Richard A. Moore, PE Telephone Number
II. PERMIT INFORMATION:
1. Specify whether project is (check one)
X New
Renewal
of project
10) 343-1048
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 NIA and its issue date (if known) N/A
3. Specify the type of project (check one):
Low Density X High Density Redevelop _General Permit Other
4. Additional Project Requirements (check applicable blanks):
CAMA Major X Sediment/Erosion Control 404/401 Permit _NPDES Stormwater
Information on required state permits can be obtained by contacting the Customer Service Center
at1-877-623-6748_
III. PROJECT INFORNIATION
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.
All stormwater will be treated through the means of two underground infiltration systems.
2. Stormwater runoff from this project drain to the Intracoastal Waterwa
3. Total Project Area:
2.84 Acres 4. Project Built Upon Area: 27.8 %
5. How many drainage areas does the project have? 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.
"'Basin'lnformation ' " s� `_a P
_'_`.�Tota] Draina �re Area
". ;"Draina e Basin-1Dr4ina
e
Receiving Stream Name
ICW
ICW
ICW
Receiving Stream Class
SA, HQW
SA, HQW
SA, HQW
Drainage Area
2.84 ac
0.85 ac
0.17 ac
Existing Impervious* Area
0.08 ac
0 ac
0.08 ac
Proposed Impervious* Area
0.79 ac
0.69 ac
0.10 ac
% Impervious* Area (total)
27.8 %
81 %
58.8 %
Im rVio.us* Surface Area
Total.Draina re Area _'
=. Draina e Basin 1.. 'r
Drainage Basin 2
On -site Building Lots
10,813 sf
10,813 sf
0 sf
On -site Asphalt Road
3,558 sf
0 sf
3,558 sf
On -site Parking
18,425 sf
18,425 sf
0 sf
On -site Sidewalks
1,002 sf
1,002 sf
0 sf
Other on -site
1,435 sf
0 sf
772 sf
Off site
0 sf
0 sf
0 sf
Total:
35,233 sf
30,240 sf
4,330 sf
* Impervious area is defined as the built upon area including, but not limited to, buildings, roads,
parking areas, sidewalks, gravel areas, etc.
Form: SWU-101 Version 3.99 Page 2 of

* Impervious area is defined as the built upon area including, but not limited to, buildings, roads,
parking areas, sidewalks, gravel areas, etc.
7. How was the off -site impervious area listed derived? NIA
IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
The following italicized deed restrictions and protective covenants are required to be recorded for all
subdivisions, out parcels and future development prior to 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.
The following covenants are intended to ensure ongoing compliance with state management permit
number as issued by the Division of Water Quality. These
covenants my not be changed or deleted without the consent of the State.
No more than 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 f lled 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 out parcels or future development shall be directed into the permitted
stormwater control systenn. 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 item 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 [phone] 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
Fonn: SWU-101 Version 3.99 Page 3 of 4

VI. SUBMITTAL REQUIRENIENTS
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.
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 Permit Application Form
• One copy of the applicable Supplement Form(s) for each BMP
• Permit application processing fee of $420 (payable to NCDENR)
• Detailed narrative description of stormwater treatment/management:
• Two copies of plans and specifications, including:
- 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)
VI. 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): McKim & Creed, PA
c
Mailing Address: 243 North Front Street
City: Wilmington State: NC Zip: 28401
Phone: [phone] Fax: [phone]
Vill. APPLICANT'S CERTIFICATION
I, (print or type name of person listed in General Inforniation, itein 2) _ Mark Evans, President
certify that the information included on this permit application form is, to the best of my knowledge, correct and
that the project will be constru ted in conformance with the approved plans, that the required deed restrictions
and protective covenants w be corded, and that the proposed project complies with the requirements of
15A NCAC 2I-1-100� /
Signature:
Date: /� p
Form: SWU-101 Version 3.99 Page 4 of4

Permit No. S\ 2 p La b 2 1
(to be provided by DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
UNDERGROUND INFILTRATION TRENCH SUPPLEMENT
This form may be photocopied for use as an original
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes a stormwater management permit application, an
underground infiltration trench supplement for each system, design calculations, and plans and specifications
showing all stormwater conveyances and system details.
I. PROJECT INFORMATION
Project Name: La Costa Bay
Contact Person: Richard A. Moore PE Phone Number: [phone]
For projects with multiple infiltration systems, a supplement form must be completed for each system. This
worksheet applies to: Trench 1 in Drainage Area 1
(from plans) (from Form SWU-101)
II. DESIGN INFORMATION (attach supporting calculations/documentation):
Soils Report Summary (based upon an actual field investigation and soil borings)
Soil Type NeE
Infiltration Rate 9.60 inlhr or cf/hr/sf (circle appropriate units)
SHWT Elevation 3.50 fmsl (Seasonal High Water Table elevation)
Trench Design Parameters
Design Volume 3,613 c.f.
Design Storm 1.5 inch event (1.5 inch event for SA waters, 1 inch event far others)
Drawdown Time 0.08 days
Perforated Pipe Size 12 inch diameter
Perforated Pipe Length 1,272 ft
No. Observation Wells
16 (may be required on a case -by -case basis)
Stone Type (if used)
#57
Stone Void Ratio
0.4
Trench Elevations (in feet mean sea level)
Bottom Elevation 5.5 fmsl
Storage/Overflow Elevation 7.0 Fmsl (at Storage Areas)
Form SWU-107 Rev 3.99 Page 1 of 4

Trench Dimensions
Height 1.5 ft. Length 154 ft.
Width 40 ft. Volume Provided 4,295 cu.ft.
III. 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, November 1995) and Administrative Code Section: 15
A NCAC 2H .1008.
Initial in the space provided to indicate that 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. Attach justification if a requirement has not been met.
Applicants Initials
System is located 50 feet from class SA waters and 30 feet from other surface waters.
b. System is located at least 100 feet from water supply wells.
Bottom of system is at least 2 feet above the seasonal high water table.
d. Bottom of the system is 3 feet above any bedrock or impervious soil horizon.
e. Off-line system, runoff in excess of the design volume bypasses the system (bypass detail
provided).
f. System is designed to draw down the design storage volume to the proposed bottom
elevation under seasonal high water conditions within five days based upon infiltration
through the bottom only (a hydrogeologic evaluation may be required).
g. Soils have a minimum hydraulic conductivity of 0.52 inches per hour.
h. System is not sited on or in fill material or DWQ approval has been obtained.
i. Plans ensure that the installed system will meet design specifications (constructed or
restored) upon initial operation once the project is complete and the entire drainage area is
stabilized.
j. System is sized to take into account the runoff at the ultimate built -out potential from all
surfaces draining to the system, including any oft -site drainage.
k. System is located in a recorded drainage easement for the purposes of operation and
maintenance and has recorded access easements to the nearest public right-of-way.
r1 I. System captures and infiltrates the runoff from the first 1.0-inch of rainfall (1.5 inch event
yLd,y1^ for areas draining to SA waters).
` m. Drainage area for the device is less than 5 acres.
Form 5WU-107 Rev 3.99
n. A pretreatment device (filter strip, grassed swale, sediment trap, etc.) is provided.
o. Trench bottom is covered with a layer of clean sand to an average depth of 4 inches.
p. Sides of the infiltration trench are lined with geotextile fabric.
q. Rock used is free of fines (washed stone) and has a large void ratio.
r. Side to bottom area ratio is less than 4:1.
s. Observation well(s) are provided (case -by -case basis).
Page 2 of 4

t. Vegetated filter is provided for overflow (50 feet for SA waters, 30 feet for other waters)
and detail is shown on plans.
1`11 u. A benchmark for checking sediment accumulation is provided.
IV. UNDERGROUND INFILTRATION TRENCH OPERATION AND MAINTENANCE AGREEMENT
1. After every runoff producing rainfall event and at least monthly inspect the bypass/overflow structure for
blockage and deterioration and the infiltration system for erosion, trash accumulation, grass cover, and general
condition.
2. Repair eroded areas immediately, re -seed as necessary to maintain adequate vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash and blockages as needed to maintain system
performance.
3. Remove accumulated sediment annually or when depth is reduced to 75% of the original design depth. Restore
depth to original design depth without over -excavating. Over -excavating may cause the required water table
separation to be reduced and may compromise the ability of the system to perform as designed.
4. The water level in any monitoring wells will be recorded after a 1-inch rainfall event and at least once a month.
Chronic high water table elevations (within I foot of the bottom of the system for a period of three months) shall
be reported to DWQ immediately.
5. If DWQ determines that the system is failing, the system will immediately be repaired or replaced to original
design specifications. If the system cannot be repaired to perform its design function, other stormwater control
devices as allowed by NCAC 2H .1000 must be designed, approved and constructed.
6. Remove accumulated sediment from the infiltration system annually or when depth in the unit is reduced to
75% of the original design depth. The system shall be restored to the original design depth without over
excavating. Over -excavating may cause the required water table separation to be reduced and may
compromise the ability of the system to perform as designed. Removed sediment shall be disposed of in an
appropriate manner and shall not be handled in a manner that will adversely impact water quality (i.e.
stockpiling near a stormwater treatment device or stream, etc.).
A benchmark shall be established in the infiltration system. The benchmark will document the original
design depth so that accurate sediment accumulation readings can be taken. The measuring device used to
determine the depth at the benchmark shall be such that it will give an accurate depth reading and not
readily penetrate into accumulated sediments.
When the depth at the benchmark reads 611 , the accumulated sediment shall be removed
from the system.
Forrn SWU-107 Rev 3.99 Page 3 of 4

I acknowledge and agree by my signature below that I am responsible for maintaining the stormwater collection
ID
system in accordance with the six 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 and Title: Mark Evans
Address: Post Office Box 2294 Wilmington NC 28402
Phone: _ 910-328-1235
Signature:
Date: d
Note: The legall}, responsible parry 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 JQ, C Qk i Sp1U , a Notary Public for the State of NdQ �`{ Y1, ti'jk&kUounty of
�)f�ew vet , do hereby certify that �a% personally appeared before me this
l3 day of and acknowledge the due execution of the forgoing infiltration
basin maintenance requirements. Witness my hand and official seal,
�OTq��'
ALL'G My commission expires
ago
Form SW U-107 Rev 3.99 Page 4 of 4

Permit No. swg cxPuz f 3
(to be provided by DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
UNDERGROUND INFILTRATION TRENCH SUPPLEMENT
This form may be photocopied for use as an original
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes a stormwater management permit application, an
underground infiltration trench supplement for each system, design calculations, and plans and specifications
showing all stormwater conveyances and system details.
I. PROJECT INFORMATION
Project Name: La Costa Bay
Contact Person: Richard A. Moore, PE Phone Number: [phone]
For projects with multiple infiltration systems, a supplement form must be completed for each system. This
worksheet applies to: Trench 2 in Drainage Area 2
(from plans)
(from Form SWU-101)
II. DESIGN INFORMATION (attach supporting calculations/documentation):
Soils Report Summary (based upon an actual field investigation and soil borings)
Soil Type
NeE
Infiltration Rate
9.60
in/hr or cf/hr/sf (circle appropriate units)
SHWT Elevation
3.50
fmsl (Seasonal High Water Table elevation)
Trench Design Parameters
Design Volume
531
c.f.
Design Storm
1.5
inch event (1.5 inch event far SA waters, I inch
event for others)
Drawdown Time
0.03
days
Perforated Pipe Size
12
inch diameter
Perforated Pipe Length
180
ft.
No. Observation Wells
10
(may be required on a case -by -case basis)
Stone Type (if used)
#57
Stone Void Ratio
0.4
SEAL
Trench Elevations (in feet mean
sea level)
= 025503
Bottom Elevation
5.5
fmsl
4,j
';���► �M��`:%' �`�
Storage/Overflow Elevation
7.0
Fmsi (at Storage Areas)
Form SWU-107 Rev 3.99 Page 1 of 4

Trench Dimensions
Height 1.5 ft. Length 40 ft.
Width 25 ft. Volume Provided 684 cu.ft.
111. 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, November 1995) and Administrative Code Section: 15
A NCAC 2H .1008.
Initial in the space provided to indicate that 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. Attach justification if a requirement has not been met.
Applicants Initials
a.
b.
C.
d.
Jam
e.
f.
g-
h.
System is located 50 feet from class SA waters and 30 feet from other surface waters.
System is located at least 100 feet from water supply wells.
Bottom of system is at least 2 feet above the seasonal high water table.
Bottom of the system is 3 feet above any bedrock or impervious soil horizon.
Off-line system, runoff in excess of the design volume bypasses the system (bypass detail
provided).
System is designed to draw down the design storage volume to the proposed bottom
elevation under seasonal high water conditions within five days based upon infiltration
through the bottom only (a hydrogeologic evaluation may be required).
Soils have a minimum hydraulic conductivity of 0.52 inches per hour.
System is not sited on or in fill material or DWQ approval has been obtained.
i. Plans ensure that the installed system will meet design specifications (constructed or
restored) upon initial operation once the project is complete and the entire drainage area is
stabilized.
j. System is sized to take into account the runoff at the ultimate built -out potential from all
surfaces draining to the system, including any off -site drainage.
k. System is located in a recorded drainage easement for the purposes of operation and
maintenance and has recorded access easements to the nearest public right-of-way.
1. System captures and infiltrates the runoff from the first 1.0-inch of rainfall (1.5 inch event
for areas draining to SA waters).
7.AA m. Drainage area for the device is less than 5 acres.
01� n. A pretreatment device (f lter strip, grassed swale, sediment trap, etc.) is provided.
Ao. Trench bottom is covered with a layer of clean sand to an average depth of 4 inches.
p. Sides of the infiltration trench are lined with geotextile fabric.
q. Rock used is free of fines (washed stone) and has a large void ratio.
r. Side to bottom area ratio is less than 4:1.
s. Observation well(s) are provided (case -by -case basis).
Form SWU-107 Rev 3.99 Page 2 of 4

t. Vegetated filter is provided for overflow (50 feet for SA waters, 30 feet for other waters)
and detail is shown on plans.
u. A benchmark for checking sediment accumulation is provided.
IV. UNDERGROUND INFILTRATION TRENCH OPERATION AND MAINTENANCE AGREEMENT
1. After every runoff producing rainfall event and at least monthly inspect the bypass/overflow structure for
blockage and deterioration and the infiltration system for erosion, trash accumulation, grass cover, and general
condition.
2. Repair eroded areas immediately, re -seed as necessary to maintain adequate vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash and blockages as needed to maintain system
performance.
3. Remove accumulated sediment annually or when depth is reduced to 75% of the original design depth. Restore
depth to original design depth without over -excavating. Over -excavating may cause the required water table
separation to be reduced and may compromise the ability of the system to perform as designed.
4. The water level in any monitoring wells will be recorded after a 1-inch rainfall event and at least once a month.
Chronic high water table elevations (within l foot of the bottom of the system for a period of three months) shall
be reported to DWQ immediately.
5. If DWQ determines that the system is failing, the system will immediately be repaired or replaced to original
design specifications. If the system cannot be repaired to perform its design function, other stormwater control
devices as allowed by NCAC 2H .1000 must be designed, approved and constructed.
6. Remove accumulated sediment from the infiltration system annually or when depth in the unit is reduced to
75% of the original design depth. The system shall be restored to the original design depth without over
excavating. Over -excavating may cause the required water table separation to be reduced and may
compromise the ability of the system to perform as designed. Removed sediment shall be disposed of in an
appropriate manner and shall not be handled in a manner that will adversely impact water quality (i.e.
stockpiling near a stormwater treatment device or stream, etc.).
A benchmark shall be established in the infiltration system. The benchmark will document the original
design depth so that accurate sediment accumulation readings can be taken. The measuring device used to
determine the depth at the benclunark shall be such that it will give an accurate depth reading and not
readily penetrate into accumulated sediments.
When the depth at the benchmark reads 6" , the accumulated sediment shall be removed
from the system.
Form SWU-107 Rev 3.99 Page 3 of 4

I acknowledge and agree by my signature below that I am responsible for maintaining the stormwater collection
system in accordance with the six 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 and Title: Mark Evans
Address: Post Office Box 2294, Wilmington NC 28402
Phone: [phone] Date: Dir
Signature:
Note: The legally res onsible 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.
` N A 1�
h,, `�1��Y� � � { � , a Notary Pubic for the State of � ip E(1�2County of
IV��}[ ICII NOUe- r` do hereby certify that ! ~ a f k OEaez y)c, personally appeared before me this
day of 1 �it'L(U,� ���(p and acknowledge the due execution of the forgoing infiltration
basin maintenance requirements. Witness myHand and official seal,
••.•O1E ruC��,'`y
��oYApy ti
"''+gNovER ��r''•
My commission expiresy 3 —) `1' ` o q
Form 5WU-107 Rev 3.99 Page 4 of 4