SW8990546_HISTORICAL FILE_20000814

STORMWATER DIVISION CODING SHEET
POST-CONSTRUCTION PERMITS
PERMIT NO. SW8 C1CJ054 v
DOC TYPE ❑ CURRENT PERMIT
❑ APPROVED PLANS
HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE 2ooD0`31`j
YYYYMMDD

State of North Carolina
Department of Environment
and Natural Resources
V1'ilmington Regional Office �'
A
James B. Hunt, Jr., Governor
Bill Holman, Secretary Nu&NR
Division of Water Qualit.N NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
August 14, 2000
Mr. Eddie Anderson. Director of Facility Planning
New Hanover COLIntV Schools
1802 S. 15th Street
Wilmington, NC 28401
Subject: Permit No. SW8 990546MOD
Williston Middle School
High Density Stormwater Project
Dear Mr. Anderson: New Hanover County
The Wilmington Reuional Office received a complete Stormwater Management Permit Application for Williston
Middle School on July 25, 2000. Staff review of the plaits 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. SWS 990546MOD dated .August 14. 2000, for the construction of Williston Middle School.
This permit shall be effective from the date of issuance until August 14,2010,and shall be subject to the conditions
and limitations as specified therein. Please pay special attention to the Operation and Maintenance requirements
in this permit.Failure to establish an adequate system for operation and maintenance ofthe stormwater management
system will result in future compliance problems.
If any parts, requirements, or limitations contained in this permit are unacceptable,you have the right to request an
adjudicatory hearing upon written request within thirty(30)days following receipt of this permit. This requestmust
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 276 1 1-7447. Unless such demands
are made this permit shall be final and binding.
If you have any questions, or need additional information concerning this matter, please contact Scott Vinson, or
me at [phone].
Sincerely,
Rick Shiver
Water Quality Regional Supervisor
RSS/sav: S:\NNIQS\STORMNN%AT\PERMIT\996546.AUG
cc: Anthony Giacoia, P.E.
Tony Roberts, New Hanover County Inspections
Beth Easley, New Hanover County Engineering
Scott Vinson
Wilmington Regional Office
Central Files
127 Cardinal Dr. Ext.,Wilmington,North Carolina 28405 Telephone [phone] FAX [phone]
An Equal opportunity Affirmative Action Employer 50014 recycled/101Y post-consumer paper

State Stormwater Management Systems
Permit No. SW8 990546MOD
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
New Hanover County Schools
Williston Middle School
New Hanover County
FOR THE
construction, operation and maintenance of a wet detention pond 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 pennit shall be effective from the date of issuance until August 14, 2010 and shall be subject to the following
specified conditions and limitations:
I. DESIGN STANDARDS
1. This permit is effective only with respect to the nature and volume of stormwater 'described in the
application and other supporting data.
2. This stormwater system has been approved for the management of stormwater runoff as described on page
3 of this permit,the Project Data Sheet. The stormwater control has been designed to handle the runoff from
97,121 square feet of impervious area.
3. Approved plans and specifications for this project are incorporated by reference and are enforceable parts
of the permit.
4. The tract will be limited to the amount of built-upon area indicated on page 3 of this permit, and per
approved plans.

State Stormwater Management Systems
Permit No. SW8 990546MOD
DIVISION OF WATER QUALITY
PROJECT DESIGN DATA SHEET
Project Name: Williston Middle School
Permit Number: SW8 990546MOD
Location: New Hanover County
Applicant: Mr. Eddie Anderson, Director of Facility Planning
Mailing Address: New Hanover County Schools
1802 S. 15th Street
Wilmington,NC 28401
Application Date: July 25, 2000
Name of Receiving Stream/Index #: Burnt Mill Creek/ 18-74-63-2
Classification of Water Body: "C Sw"
If Class SA, chloride sampling results: n/a
Pond Depth, feet: 3.50
Permanent Pool Elevation, FMSL: 37.25
Drainage Area, acres: 3.11
Total Impervious Surfaces, ft': 97,121
Buildings, ft': 37,984
Sidewalks; ft2: 11,520
Parking, ft': 27,835
Other On-Site, ft2: 19,782
Offsite Area entering Pond, ft2: none, per Engineer
Required Surface Area, ft': 9,712
Provided Surface Area, ft': 10.813
Required Storage Volume, ft': 7,849
Provided Storage Volume, ft': 8,712
Temporary Storage Elevation, FMSL: 38.00
Controlling Orifice: 1.50" � pipe
3

State Stormwater Management Systems
Permit No. SW8 990546MOD
II. SCHEDULE OF COMPLIANCE
1. The stormwater management system shall be constructed in it's entirety, vegetated and operational for its
intended use prior to the construction of any built-upon surface.
3. During construction,erosion shall be kept to a minimum and any eroded areas of the system will be repaired
immediately.
I The permittee shall at all times provide the operation and maintenance necessary to assure the permitted
stormwater system functions at optimum efficiency. The approved Operation and Maintenance Plan must
be followed in its entirety and maintenance must occur at the scheduled intervals including, but not limited
to:
a. Semiannual scheduled inspections (every 6 months).
b. Sediment removal. .
C. Mowing and revegetation of side slopes.
d. Immediate repair of eroded areas.
e. Maintenance of side slopes in accordance with approved plans and specifications.
f. Debris removal and unclogging of outlet structure, orifice device and catch basins and piping.
g. Access to the outlet structure must be available at all times.
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. Decorative spray fountains will not be allowed in the stormwater treatment system.
6. 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.
7. 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.
8. 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.
9. The following items will require a modification to the permit:
a. Any revision to the approved plans, regardless of size.
b. = Project name change.
C. Transfer of ownership.
d. Redesign or addition to the approved amount of built-upon area.
e. Further subdivision,acquisition,or sale of the project area.The project area is defined as all property
owned by the permittee, for which Sedimentation and Erosion Control Plan approval was sought.
f. Filling in, altering, or piping of any vegetative conveyance shown on the approved plan.
10. The Director may determine that other revisions to the project should require a modification to the permit.
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.
4

State Stormwater Management Systems
Permit No. SW8 990546MOD
12. Prior to the sale of any portion of the property,an access/maintenance easement to the stormwater facilities
shall be granted in favor of the permittee if access to the stormwater facilities will be restricted by the sale
of any portion of the property.
13. The permittee is responsible for verifying that the proposed built-upon area does not exceed the allowable
built-upon area.
14. The runoff from all built-upon area on the project must be directed into the permitted stormwater control
system.
15. 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.
16. The permittee shall notify the Division of any mailing address changes within 30 days.
III. GENERAL CONDITIONS
1. This permit is not transferable. In the event there is a desire for the facilities to change ownership,or there
is a name change of the Permittee, a formal permit request must be submitted to the Division of Water
Quality accompanied by an application fee,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.
2. Failure to abide by the conditions and limitations contained in this permit may subject the Permittee to
enforcement action by the Division of Water Quality, in accordance with North Carolina General Statute
143-215.6A to 143-215.6C.
3. The issuance of this permit does not preclude the Permittee from complying with any and all statutes,rules,
regulations, or ordinances which may be imposed by other government agencies(local, state, and federal)
which have jurisdiction.
4. In the event that the facilities fail to perform satisfactorily, including the creation of nuisance conditions,
the Permittee shall take immediate corrective action, including those as may be required by this Division,
such as the construction of additional or replacement stormwater management systems.
5. The permittee grants DENR Staff permission to enter the property 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 Plamr rig and Design Manual.
Permit issued this the 14th day of August, 2000.
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
Ken T. Stevens, Director
Division of Water Quality
By Authority of the Environmental Management Commission
Permit Number SW8 990546MOD
5

State Stormwater Management Systems
Permit No. SW8 990546MOD
Williston Middle School
Stormwater Permit No. SW8 990546MOD
New Hanover County
Designer's Certification
1, as a duly registered in
the State of North Carolina, having been authorized to observe (periodically/weekly/full time)the construction of
the project;
(Project)
for (Project Owner)hereby state that,to the best ofmy 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:
i
SEAL
Signature
Registration Number
Date
6

State Stormwater Management Systems
Permit No. SW8 990546MOD
Certification Requirements:
1. The drainage area to the system contains approximately the permitted acreage.
?. The drainage area to the system contains no more than the permitted amount of built-upon area.
3. All the built-upon area associated with the project is graded such that the runoff drains to the system.
4. The outlet/bypass structure elevations are per the approved plan.
5. The outlet structure is located per the approved plans.
6. Trash rack is provided on the outlet/bypass structure.
7. All slopes are grassed with permanent vegetation.
8. Vegetated slopes are no steeper than 3:1.
9. The inlets are located per the approved plans and do not cause short-circuiting of the system.
10. The permitted amounts of surface area and/or volume have been provided.
11. Required drawdown devices are correctly sized per the approved plans.
12. All required design depths are provided.
13. All required parts of the system are provided, such as a vegetated shelf, and a forebay.
14. The overall dimensions of the system, as shown on the approved plans, are provided.
cc: NCDENR-DWQ Regional Office
Tony Roberts,New Hanover County Building Inspector
7

.;' "OPFICEUSEDNLY'. "'"'• .,++n.="pas
Date Received Fee Paid Permit Number .
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form may be photocopied for use as an original
I. GENERAL INFORMATION
1. Applicants name(specify the name of the corporation,individual,etc.who owns the project):
New Hanover County Schools
2. Print Owner/Signing Official's name and title(person legally responsible for facility and compliance):
Eddie Anderson, Director of Facility Planning
3. Mailing Address for person listed in item 2 above:
1802 S. 15th Street
City: Wilrington State: NC Zip: 28401
Telephone Number: ( 910 ) 763 5431
4. Project Name(subdivision,facility,or establishment name-should be consistent with project name on
plans,specifications,letters,operation and maintenance agreements,etc.):
Williston Middle School
Phase II Renovation
5. Location of Project(street address):
401 South loth Street
City: Wilmington County: New Hanover
6. Directions to project(from nearest major intersection):
Located at loth and Ann Streets
7. Latitude: 770 56' 0011 Longitude: 340 14' 00" of project
8. Contact person who can answer questions about the project:
Name: Ron Sparks Telephone Number: ( 910 ) 254-4323
II. PERMIT INFORMATION:
1. Specify whether project is(check one): New Renewal Modification
SW-5 5G054(o)
Form SWU-101 Version 3.99 Page 1 of 4

2. If this application is being submitted as the result of a renewal or modification to an existing permit,list the, ,
existing permit number and its issue date(if known)
3. Specify the type of project(check one):
_Low Density - X High Density _Redevelop _General Permit _Other
4. Additional Project Requirements(check applicable blanks):
_LAMA Major Y Sedimentation/Erosion Control _404/401 Permit _NPDES Stormwater
Information on required state permits can be obtained by contacting the Customer Service Center at
1-877-623-6748.
III. PROJECT INFORMATION
1. In the space provided below,summarize how stormwater will be treated. Also attach a detailed narrative
(one to two pages) describing stormwater management for the project.
Stormwater will be treated in a storrmater detention pond.
2. Stormwater runoff from this project drains to the rn,A Fear River basin.
3. Total Project Area:_9.1 acres 4. Project Built Upon Area: 48 %
5. How many drainage areas does the project have? 2
6. Complete the followwing 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.
8asm InforntaUon Dramage'Area:l � Dratnage'Aiea 2
Receiving Stream Name Burnt Mill Creek
Receiving Stream Class C SW
Drainage Area 3.11 acres Existing Facilities
Existing Impervious*Area 26,180 SF
Proposed Im ervious"Area 97. 121 Si
%Impervious*Area(total) 72%
Im'ervious�ySttifaceAieae. .fi �" � 3DramageTAreal ��� � �'�` Dramage"Aea2
On-site Buildings 37,984
On-site Streets N/A
On-site Parking 27,835 SF
On-site Sidewalks 11 ,520'SF
Other on-site 19 782• S
Off-site
Total: 97,121 SF Total:
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 4

7. How was the off-site impervious area listed above derived? N/a
IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
The following italicized deed restrictions and protective covenants are required to be recorded for all
subdivisions,outparcels and future development prior to the sale of any lot. If lot sizes vary significantly,a
table lis ing'each lot number,size and the allowable built-upon area for each lot must be provided as an
attachment:;
. 1 .
1. The following covenants are intended to ensure ongoing compliance with state stormwater management permit
number as issued by the Division of Water Quality. These covenants may
not be changed or deleted without the consent of the State.
2. No more than square feet of any lot shall be covered by structures or impervious materials.
Impervious materials include asphalt,gravel,concrete,brick,stone,slate or similar material but do not include wood
decking or the water surface of swimming pools.
3. Swales shall not be filled in,piped,or altered except as necessary to provide driveway crossings.
4. Built-upon area in excess of the permitted amount requires a state stormwater management permit modification prior to
construction.
5. All permitted runoff from outparcels or future development shall be directed into the permitted stormwater control
system. These connections to the stormwater control system shall be.performed in a manner that maintains the
integrity and performance of the system as permitted.
By your signature below,you certify that the recorded deed restrictions and protective covenants for this project
shall include all the applicable items required above, that the covenants will be binding on all parties and
persons claiming under them,that they will run with the land,that the required covenants cannot be changed or
deleted without concurrence from the State,and that they will be recorded prior to the sale of any lot.
V. SUPPLEMENT FORMS
The applicable state stormwater management permit supplement form(s)listed below must be submitted for
each BMP specified for this project. Contact the Stormwater and General Permits Unit at(919)733-5083 for the
status and availability of these forms.
Form SWU-102 Wet Detention Basin Supplement
Form SWU-103 Infiltration Basin Supplement
Form SWU-104 Low Density Supplement
Form SWU-105 Curb Outlet System Supplement
Form SWU-106 Off-Site System Supplement
Form SWU-107 Underground Infiltration Trench Supplement
Form SWU-108 Neuse River Basin Supplement
Form SWU-109 Innovative Best Management Practice Supplement
Form SWU-101 Version 3.99 Page 3 of 4

VI. SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Water Quality(DWQ).
A complete package includes all of the items listed below. The complete application package should be
submitted to the appropriate DWQ Regional Office.
1. Please indicate that you have provided the following required information by initialing in the space
provided next to each item.
Jidtials
• 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)
VII. AGENT AUTHORIZATION
If you wish to designate authority to another individual or firm so that they may provide information on your
behalf,please complete this section.
Designated agent(individual or firm): Eddie Anderson
Mailing Address: New Hanover County Schools , 1802 S . 15th Street
City: Wilmington State: NC Zip: 28401
Phone: ( 910 ) 763-5431 Fax: ( 910 ) 254-4238
VIII. APPLICANT'S CERTIFICATION
I,(print or type name of person listed in General Information, item 2) Eddie Anderson
certify that the information included on this permit application form is,to the best of my knowledge,correct and
that the project will be constructed in conformance with the approved plans,that the required deed restrictions
and protective covenants will be recorded,and that the proposed project complies with the requirements of 15A
NCAC 2H.1000. //
Signature: e,_ de_ 4L L�, Date: 1(1111.27
Form SWU-101 Version 3.99 Page 4 of 4

1
❑®� Kimle -Horn Wilmington,
Franklin Ave.,fl 227
y Wilmington,NC 28403
® ._..._._ and Associates, Inc.
RECEIVED TEL [phone]
Transmittal
JUL 2 4 2000 FAX [phone]
BY:
Date: July 20,2000 Job.No: 01 104700
To: Scott Vinson
NCDENR
Via hand delivery
Re: Williston Middle School,Request for Additional Information,Stormwater Project No.SW8 990546MOD
We are sending you
®Attached ❑ Under separate cover via the following items:
❑ Shop Drawings ® Prints/Plans ❑ Samples ❑ Specifications ❑Change Orders
❑ Other:
Copies Date No. Description
1 07.19.00 2 Revised plan sheets C4.1 and C7.1
0�1-
' - A C-7Y
These are transmitted as checked below: fAQA Co.
® For your use ❑ Approved as submitted ❑ Resubmit ❑ Copies for approval
® As requested ❑ Approved as noted ❑ Submit ❑ Copies for distribution
❑ For review and comment ❑ Returned for corrections ❑ Return ❑ Corrected prints
Rentarks
Scott
Per your request,the C4.1 and C7.1 plan sheets for Williston Middle School have been modified.
Per our discussion yesterday, the grading at the access drive has been revised such that all runoff
outside of the 10"St. right-of-way flows back to the new curb inlet. All other requests listed in your
letter of July 13, 2000 have also been incorporated.
If you could, please let me know if the attached plans meet your requirements, and when the permit
will be issued.
Thanks for your help with this.
Copy to: Signed:
Antho y J. iacoia, P.E.

® Kimle -Horn 4607 Franklin Ave.,ti 227
Wilmington,NC 28403
C�� y and Associates, Inc.
TEL [phone]
FAX [phone]
Transmittal
RF"- "_ i E
JUL 2. 5 Date: July 21,2000 Job.No: 011047003
zoaQ
To: Scott Vinson
BY. NCDENR
Via hand delivery
� E C E B V E
Re: ftlislon Middle School,Request for Additional Information,Stormwater Project No.SWS 990546MOD
JUL 2 5,20Weare sending),on
DWQ. ®Attached ❑ Under separate cover via the following items:
�pa$�----------❑ Shop Drawings ® Prints/Plans ❑ Samples ❑ Specifications E]Change Orders
❑ Other:
Copies Date No. Description
1 07.19.00 2 Revised plan sheets C4.1 and C7.1
These are transmitted as checked below:
® For your use ❑ Approved as submitted ❑ Resubmit ❑ Copies for approval
® As requested ❑ Approved as noted ❑ Submit ❑ Copies for distribution
❑ For review and comment ❑ Returned for corrections ❑ Return ❑ Corrected prints
Remarks
Scott:
Second copy,per your request.
Copy to: Signed:
Anth y . Giacoia, P.E.

—FILE No.684 07/19 '00 09:27 ID:KIMLEY-HORN FAX:[phone] PAGE 1/ 3
® Kimley-Hom 4607 Franldin Avenue
®® and Associates, Inc suue 227
Wilmington,N.C.28403
9101792-1040
FAX [phone]
Fax Memo
To: Scott Vinson Fax No: 350-2004
Firm/Location: NCDENR Pro'. No.: 018047003
From: Anthon J. Giacoia P.E. Date: 7.19.00
Re: Williston Middle School, SW8 990546MOD
Original coming by mail: Yes: No: X
Scott:
Per your request, I have modified the grading and drainage plan for Williston Middle
School Phase 2 Renovations. I have added a curb inlet along the entry drive in order to pick
up and treat additional runoff that was draining to I&St. This design will still allow some
untreated runoff, but because of grade constraints I cannot locate this inlet any closer to 10'
St. (insufficient cover). Page-1, attached, shows the location of this inlet.
1 have also made some adjustments to the retention pond (see Page-2). The proposed
retention pond has a permanent pool surface area of 10,813 SF. For a 3:1 length-to-width
ratio, the pond would have the idea dimensions of 180' by 30'. With the addition of the
spillway from the forebay to the main pool and the arrangement of the baffle as shown on
Page-2,I have an approximate flow length of 205',which appears to meet the length-to-
width requirement.
Please review these changes, and provide any comments.
Thanks.
10�
4
"1wV5 `7" C,'(J / �
0
This facsimile is intended only for the addressee named herein and may contain information that is confidential Il you are not
the intended recipient or the employee or agent responsible for delivery to the addressee,yNw.hereby notified that any
review,dissamina lion,disclosure,or copying of this communka lion is srdclly prohibited. If yo`u_tiara received this facsimile in
error,please immediately notify us by telephone,and return the original facsimile to us at the address above via the U.S.Postal
Service, Thank you
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State of North Carolina
Department of Environment
and Natural Resources GO
e
Wilmitiglon Regional Office ;
� 11
James B. Hunt, Jr., Governor
Bill Holman`,,Secretary Ce oil;hE N
}�
Division of Water Quality NORTH CAROLINA (DEPARTMENT OF
July 1 2000 ENVIRONMENT AND NATURAL RESOURCES
Mr. Chris Ford, P.E.
Kimlev-Horn and Associates. Inc.
4607 Franklin Ave., Suite 227
Wilmington, NC 28403
Subject: ACKNOWLEDGMENT OF RECEIPT AND
REQUEST FOR ADDITIONAL INFORMATION
Stormwater Project No. SW8 990546MOD
Williston Middle School
New Hanover County
Dear Mr. Ford: _.
The Wilmington Regional Office received a Stormwater Management Permit Application for
Williston Middle School on May 9, 2000. A preliminary review of that information has determined that the
application is not complete. The following information 1s needed-to continue the stormwater review:
1. Delineate all wetlands on site, or note on the plans that none exist.
2. Per my phone conversation with Anthony Giacoria I have revised the sediment removal
benchmark elevations on page 3 of 4 of the Wet Detention Basin Supplement. The
benchmark elevations for the main pond and forebay are 2.65 feet and 2.45 feet respectively.
3. On sheet C7.1 of the plans; the detail of the outlet structure gives a 1.0 inch diameter orifice.
Please revise plans to show a 1.5 inch diameter orifice as noted on the application.
i'le€^e Pxtend the baffles Lo the edge of the pond on the ditigrani given on sheet 4.i.
5. The 3:1, Length:Width requirement for the pond has not been meet. As per the phone
conversation with Mr. Giacoria, a final design has been reached of fore bay wier and baffles
combinations that give the pond the 3:1, L:W requirement.
6. ae � .6 0sg1 e e
There is 2 prQXlm t 1 r 2 ( ^L' et Of entry driver ::ef ieri
not being COtle::
r ,--L-d To the pt , d .r r'_E yJe the street an&r adn t dint:, t ' .,rop iu ets in order ;:
pick up and treat the runoff Lroin this portion of the project.
127 Cardinal Dr.Ext.,Wilmington,North Carolina 28405 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 500% recycled110% post-consumer paper

Mr. Ford
July 13, 2000
Stonnwater Project No. SR'8 990546MOD
----------------------------------------------
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 13, 2000, or the application will be
returned as incomplete. The return of a project will necessitate resubmittal of all required items, including
the application fee.
If you need additional time to submit the information, please mail or fax your request for a time
extension to the Division at the address and fax number at the hottom of this letter. ThP request must
indicate the date e,y which you expect to sa. init the required information. The Division is allowed 90
days from the receipt of a completed application to issue the permit.
The construction of any impervious surfaces, other than a construction entrance under an approved
Sedimentation Erosion Control Plan, is a violation ofNCGS 143-215.1 and is subject to enforcement action
pursuant to NCGS 143-215.6A.
Please reference the State assigned project number on all correspondence. Any original documents
that need to be revised have been sent to the engineer or agent. All original documents must be returned or
new originals must be provided. Copies are not acceptable. If you have any questions concerning this
matter please feel free to call me at [phone].
Sincerely,
Scott Vinson
Environmental Engineer
RSS/sav: S:\WQS\STORMWAT\ADDINFO\990546.JUL
�� �Jii._�ington Regional Office
Eddie Anderson, N.H. County Schools

Mr. Ford
July 1'), 2000
Stormwater Project No. SW8 990546MOD
----------------------------------------------
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 13, 2000, or the application will be
returned as incomplete. The return of a project will necessitate resubmittal of all required items, including
the application fee.
If you need additional time to submit the information, please mail or fax your request for a time
extension to the Division at the address and fax number at the bottom of this letter. The request must
indicate the date by which you expect to sabinit the required information. The Division is allowed 90
days from the receipt of a completed application to issue the permit.
The construction of any impervious surfaces, other than a construction entrance under an approved
Sedimentation Erosion Control Plan, is a violation ofNCGS 143-215.1 and is subject to enforcement action
pursuant toNCGS 143-215.6A.
Please reference the State assigned project number on all correspondence. Any original documents
that need to be revised have been sent to the engineer or agent. All original documents must be returned or
new originals must be provided. Copies are not acceptable. if you have any questions concerning this
matter please feel free to call me at [phone].
Sincerely,
Scott Vinson
Environmental Engineer
RSS/sav: S:\WQS\STOR.MWAT\ADDINFO\990546.JUL
cc: Wiim;ngton Regional Office
Eddie Anderson,N.H. County Schools

M
STORMWA TER MANAGEMENT NARRATIVE
For
WILLISTON MIDDLE SCHOOL PHASE II
RENOVATIONS
NEW HANOVER COUNTY SCHOOLS
NEW HANOVER COUNTY, NC
,••••••����F S8 p;Y-
= SEAL
20149 _
's
FNG!NE,q�.O .
RIS
May 2000
Kimley—Horn and Associates, Inc.
4607 Franklin Avenue
Wilmington, NC 28403
910-792-1040
Kimley-Horn and Associates, Inc. Project No. 018047003

Stormwater Management Narrative
Project Description
The New Hanover County School System plans to construct site improvements
for Williston Middle School beginning in the summer of 1999. The site
improvements will take place in two phases. The erosion control plan phasing will
coincide with the project phasing. The first phase consists of the demolition of the
existing band building, the second story portion of the Annex building, related
utilities and walkways, and assorted drives, walks and miscellaneous site
elements. The second phase consists of demolition of an asphalt parking lot and
new construction to include the following:
• A 6" Grade House
• A building to house Business Education, Family & Consumer Science
and a Media Center
• A building to house Visual Arts, Special Education, Administration,
Guidance Department and a Computer Lab
• A main entry
• A service drive, dumpster pad, cooling towers and electrical
transformers
• Renovations to the Williston Main Building
A grassed and paved play area will be added in a future third phase.
The total parcel size is approximately 35 acres. The area to be disturbed during
Phase 1 demolition activity is approximately 0.47 acres. The area to be disturbed
in Phase 2 construction activity is approximately 2.84 acres. The project is
located within the City limits of Wilmington between 10" and 11" Streets
between Ann and Castle Streets. The parcel is currently zoned O&I. The proposed
and existing uses are permitted within the O&I zoning and will not require any
special use permits.
Site Description
The site consists of relatively flat with slopes ranging from 0% to 2%. Elevations
range from approximately 43 MSL TO 46 MSL. The site is relatively clear of
trees and consists of school buildings, play grounds and a maintenance yard.
Adjacent Property
Williston Middle School Phase II Renovations Page 2 of 7
KHA Project No. 018047003 May 2000

Stormwater Management Narrative
The adjacent property is zoned residential. Gregory Middle School is located on
the northwest corner of the parcel, with proposed New Hanover County practice
fields to be located to the east.
Soils
The predominant soil type is Leon as indicated on the New Hanover County Soils
Survey. Detailed soil investigations have been completed to establish the
seasonal high water table for permanent stormwater control measures. The
investigation is included as an attachment. Anticipated permanent stormwater
measures will include drop inlets, piping, and a detention pond. An infiltration
system is not feasible for this site due to a seasonal high water table that is close
to the existing ground surface.
Stormwater Control Devices
The stormwater from the parking lot is collected in a series of five (5) drop inlets
that convey the stormwater to a detention pond. Runoff from the proposed hard
courts as well as the stormwater between these courts and the new building is
collected by an additional drop inlet and directed to the pond. An additional line
of four (4) inlets is located between the new and existing buildings, and to the
south of the existing building. This line ties into the previous line at a manhole
located along 11'h Street. The combine flow is then directed to the wet detention
basin. The discharge from the basin ties into a City of Wilmington 48" storm
drainage line on 13'h Street near Ann Street.
The detention pond was designed according to NCDENR-DWQ guidelines,
collecting and storing the runoff from the first 1" of rainfall and discharging it
over a 2-5 day period.
Due to limited space and a high seasonal high water table, the pond could not be
sized to meet City of Wilmington guidelines, which require that the post-
development discharge be less than the predevelopment discharge. Because the
impervious surface is reduced by the proposed construction when the Williston
and New Hanover Practice Fields Projects are combined, the City has agreed to
allow the "payment in lieu"option as an alternative.
Other stormwater control devices were designed for the 10-year, 6-hour storm
event and evaluated based on the 50-year storm event as required by the City of
Wilmington Stormwater Ordinance.
Williston Middle School Phase H Renovations Page 3 of 7
KHA Project No. 018047003 May 2000

Stormwater Management Narrative
Erosion Control Devices
Erosion control devices have been designed to limit the effects of the erosion and
sedimentation for the disturbed area. Stormwater will be discharged to the City of
Wilmington stormwater system as there is no other outlet for stormwater. Devices
to be installed are as follows:
Silt Fence — Silt fence will be installed at particular locations as indicated
on the plans to trap and retain sediment on site during both Phases.
Inlet Protection Device — Inlet protection devices will not be installed at
all catch basins due to the existing concrete surrounding the inlets. Silt
fence will be installed instead upstream of all inlets.
Preliminary Construction Sequence
1. Obtain Sedimentation and Erosion Control Plan approval.
2. Obtain other applicable permits.
3. Install silt fence.
4. Clear and grub areas necessary for installation of erosion control
measures.
5. Proceed with demolition.
6. Maintain all erosion control devices throughout demolition and
construction.
7. Construct sediment traps and diversion ditches as indicated on the site
plans or as necessary to retain sediment on site.
8. Perform grading operations.
9. Construct permanent stormwater control measures.
10. Install inlet protection around newly constructed storm water catch basins
and drop inlets.
11. Construct new building, utilities, paving, and walks.
12. Stabilize and seed all denuded areas and side slopes.
Williston Middle School Phase 11 Renovations Page 4 of 7
KHA Project No. 018047003 May 2000

Stormwater Management Narrative
13. Remove temporary sediment and erosion control devices after construction
is complete and vegetation has been established.
Stormwater Management Maintenance Plan
Stormwater Detention Pond:
1. Grassing around any detention/retention facility shall be maintained to
prevent the erosion of these areas. The areas shall be periodically mowed
to maintain the aesthetic quality of the site and to prevent a reduction in
capacity of the stormwater system. Grass on slopes should not exceed a
height of 6 inches. Repair eroded areas immediately.
2. Open ditches shall be kept free of undesirable growth and mowed or
maintained to the design cross-section and area as shown on the
Stormwater Management Plan approved by the City and on file in the
office of the City Engineer. Growth on the slopes and bottom should not
exceed a height of 8 inches.
3. Landscaping of the area around the detention/retention facility shall not
reduce the capacity or hinder operation and maintenance of the stormwater
system.
4. Check and clear the orifice of any obstructions such that the drawdown of
the temporary pool occurs within 2-5 days as designed
5. The facility shall be routinely checked for and cleared of all accumulation
of debris and the detention/retention facility outlet structure cleared of any
blockage that is present.
6. Storm drainage pipes and culverts shall be periodically inspected
(quarterly as a minimum) for debris and sand build-up. They shall be
cleaned as necessary to provide for the free conveyance of stormwater as
designed.
7. The detention/retention facility shall be maintained at the design depth as
shown on the Stormwater Management Plan approved by the City and on
file in the office of the City Engineer. The pond shall be inspected after
every significant runoff producing rainfall event and at least monthly.
Debris and sedimentation shall be removed at least semi-annually or if:
Williston Middle School Phase II Renovations Page 5 of 7
KHA Project No. 018047003 May 2000

Stormwater Management Narrative
a. The primary outlet capacity is impaired and/or
b. The depth of the facility is more than one foot above the original
facility depth or facility volume is reduced by 25% of the design
impoundment volume. When the permanent pool depth reads
�57 33r7§feet in the main pond or3 .@@ feet in the forebay, the
sediment shall be removed. 'y Y
Removed sediment shall be disposed of in an appropriate manner and shall
be handled in a manner that will not adversely impact water quality (i.e.
stockpiling near a wet detention basin or steam, etc.).
8. Landscaping shall be maintained to ensure that landscape materials live
and prosper.
9. Remove cattails and other indigenous wetland plants when they cover
50% of the basin surface. These plants shall be encouraged to grow along
the vegetated shelf and forebay berm.
10. If the basin must be drained for an emergency or to perform maintenance,
the flushing of sediment through the emergency drain shall be minimized
to the maximum extent practical.
Erosion Control Maintenance Plan
1. The general contractor will check for stability and operation of all erosion
control measures following every runoff-producing rainfall. As a
minimum, all erosion and sedimentation control devices shall be checked
no less than once every week. Any needed repairs will be made
immediately to maintain all devices as designed.
2. The sediment traps and rock dams will be cleaned out when the storage
capacity has been approximately 50% filled. Gravel will be cleaned or
replaced when the sediment pool no longer drains properly.
3. Sediment will be removed from behind the sediment fencing when it
becomes 6-inches deep at the fence. The fencing will be repaired as
necessary to maintain a sufficient barrier.
4. All seeded areas will be fertilized, re-seeded as necessary, and mulched
according to the plans and specifications to maintain a vigorous, dense
vegetative cover.
5. See the construction plans for additional notes and details.
Williston Middle School Phase H Renovations Page 6 of 7
KHA Project No. 018047003 May 2000

Stormwater Management Narrative
Vegetative Plan
See the erosion control detail sheets and landscape plans for guidance for
establishing vegetation.
Project Address
Williston Middle School
401 South 10' Street
Wilmington,North Carolina
Property Owner
New Hanover County Schools
1802 South 15" Street
Wilmington, North Carolina 28401
[phone]
Attn.: Carmen Gintoli, Project Manager
Civil Engineering and Landscape Architecture
Kimley-Horn and Associates, Inc.
4607 Franklin Avenue, Suite 227
Wilmington,NC 28403
[phone]
Attn.: Mr. J. Chris Ford, P.E.
K:\PN\0I804703\SW Narrative.doc
Williston Middle School Phase 77 Renovations Page 7 of 7
KHA Project No. 018047003 May 2000

Existing Impervious Area Calculation 5/3/00
Site: Williston Middle School (TOTAL)
KHA Project No.018047003
Description Buildings Streets/Parking Sidewalks Other
# SF Total SF # SF Total SF # SF Total SF # SF Total SF
Parking/Streets 1 9,883 9,883
Bldg-1 1 34,841 34,841
61dg-2 1 14,397 14,397
Bldg-3 1 41,320 41,320
Bldg-4 1 13,963 13,963
Bldg-5 1 2,566 2,566
Concrete Walk aorund Bidg-1 1 6,275 6,275
Concrete Walk aorund Bldg-2 1 3,025 3,025
Concrete Walk aorund Bldg-3 1 4,939 4,939
Concrete Walk aorund Bldg-4 1 2,240 2,240
Concrete Walk aorund Bldg-5 1 1,411 1,411
Sub-Total Existing Impervious Area (sf) 107,0871 9,8831 1 1 17,890 0
Total Existing Impervious Area (sf) 134,860
Total Existing Impervious Area (acres) 3.10
Total Site Area (acres) 9.09
Existing Percent Impervious 34.06%
K:\PN\01804703\Calcs\lmpewious_Area_Calc.xis\Existing-Williston Page 1 of 1

Proposed Impervious Area Calculation 5/3/00
Site: Williston Middle School (TOTAL) f
KHA Project No. 018047003
Description Buildings Streets/Pking Sidewalks Other
# SF Total SF # SF Tarotal SF # SF Total SF # SF Total SF
Existing Bldg-1 1 33,832 33,832
Existing Bldg-2 1 14,397 14,397
Existing Bldg-3 1 41,320 41,320
New Bldg-1 1 38,010 38,010
Existing Concrete Walk around Exist. Bldg-1 1 6,275 6,275
Existing Concrete Walk around Exist. Bldg-2 1 3,025 3,025
Existing Concrete Walk around Exist. Bldg-3 1 4,939 4,939
Concrete Walk around new Bldg-1 1 11,520 11,520
Paved Play Area 1 9,776 9,776
New 73 Car Parking Lot 1 27,150 27,150
Sub-Total Impervious Area(sf) 127,559 27,150 25,759 1 9,776
Total Impervious Area (sf) 190,244
Total Impervious Area (acres) 4.37
Total Site Area(acres) 9.09
Proposed Percent Impervious 48.05%
Percent of Pervious Increase 41%
S:\01804703\Cake\Impervious_Area_Calc.xls\Proposed-Williston Page 1 of 1

Kimley-Horn
and Associates,Inc.
Sheet Na 2 0l 3
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
Site:Williston Middle School TRIBUTARY TO POND
TOTAL AREA INTO POND 3.11 ac. = 135,472 sf.
Impervious Areas Draining to Pond
New Building 0.87 = 37,984 sf. a
Parking/Drives 0.64 = 27,835 sf. 01
Hard Court 0.23 = 9,870 sf.
Chillers 0.03 = 1,200 sf.
Sidewalks 0.26 = 11,520 sf.
Other(10%) 0.20 - 8,712 sf.
TOTAL 2.23 = 97,121 sf.
PERCENT IMPERVIOUS 71.69%
rMilliston_Deten_Pond ArevAxls NCDENR

STORMWATER DESIGN CALCULATIONS
For
WILLISTON MIDDLE SCHOOL PHASE II
RENOVATIONS
NEW HANOVER COUNTY SCHOOLS
NEW HANOVER COUNTY,NC
May 2000
Kimley—Horn and Associates, Inc.
4607 Franklin Avenue
Wilmington,NC 28403
910-792-1040
Kimley-Horn and Associates, Inc. Project No. 018047003

Kimley-Horn
and Associates,Inc.
Sheet No 1 0/3
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJCx Date 3117100 Checked by Date
NCDENR METHOD (for"first flush'pollution removal efficiency)
Minimum Permanent Pool Surface Area Determination Vegetated Filter No P.P.E ?-37:25
Impervious Total Percent Perm. SA/DA Area Permanent Pool Bottom
Area(ac) Area(ac) Impervious Depth(ft) Ratio (sf) W(ft) L(ft) Elev.(ft.)
ALT#1 2.23777 3.11, :=i. 72% 3.0 "7 5 °i 10,160 59 182 34.25
ALT#2 2.23 3.11 72% i 3.5 ,I I: '6.4 1 8,670 54 167 33.75
ALT#3 2.23 3.11 72°h ,.4.0,1;. , 'i"5.6'"1 7,586 51 158 33.25
ALT#4 2.23 3.11 72% 9.5,:: 5_I __1 6,909 48 149 32.75
Per NCDENR requirements,collect the runoff from the first 1"of rainfall
1"Runnoff Volume determined by the Simple Method(Tom Schueler)
Rv=(0.05+.009(%imp.))(1")(1712")(acres)(43,560011 acre)
Minimum Top of Berm Surface Area Determination 01 inches rainfall
Runnoff Depth Volume Freeboard(ft) Top of Berm Total
Volume(cf) for RV Check(cf) W(ft) Lift) Depth
ALT#1 7,849 0.73 8,242
ALT#2 7,849 0.87 8,363 66 179 5.4
ALT#3 7,849 0.97 8,461 F6.0
ALT#4 7,849 1.10 8,585 �1� 61 162 6.6
Calculate the Composite C value for City of Wilmington design
Pavement C= 0.95 Composite C= 0.74
Landscaped C= 0.20
Calculate the SCS Curve Number for City of Wilmington design
Apshalt CN= 98
Leon Soil CN= 69 (Postdevelopment)
Composite Post-development CN= (%impervious)(asphalt CN)+(%pervious)(pervious CN)
= 90
r\\Williston_Delon_Pond Arev4xls NCDENR

STORM DRAINAGE DESIGN DATA SHEET
Pmpnl NumEer. 01SU7003 D. ,.By: aG Dew W171m Fopp Nunn: oIBW7003 DesimeE By: aB
Reject Witia.Mimes W CMhee By: sues, 1.12 pn a Y0161mM esawn Geckea Br: n D.,
S1wmRcuawx, 10 Yew Pipe Tra: BOP n-v.N.: 0.012 2-,.xax ninkl: 45 Surface n-value: Doti Ca:Dm
1 x 3 4 s 6 T a 9 10 11 12 13 14 15 16 1] 19 le 20 H s
Loc.Bm M. PIPE DATA DMINAGE AS.MTw xpnulw GWa 11ne 1nYyYe 5ubm,pawe
Sul, INH PO. Tc 1 C W. Seiren US TOW DS Us Been Basin Basin
TOW r a o=cu $Icpe _ s e vN0 LenDT 141i'l, s1w1 D,ebb aP^•.
F- T. Total Pme Tlme Inlens4 FunOD 1 ( 1 Ne on 14s) (hell T1mp Im'M Pyw Fell Inva1 Tap D. Len96i HeiDliI s1Ope lmal FWn I„inl I Men ✓.van ZB to 018 OU 4rn„ bbpn
leave) Ilan) One) Imn) anc, (mM) C«I (ck BM OnJ (min) (ft) (ft) Iel (3) (ft 18) (ull_)
ro
CO-6 DI-I 0.287 0,287 7.23 ON IS
CW2 DI-3 0,287 0287 7.23 0.90 1.9
CP24 DI-4 0.287 0,287 7,23 0,90 1.9
M14 DI-8 0.105 0.105 7.23 0ED C7
CO-6 DI-9 0.194 0,191 723 0.90 1.2
DI-1 DI-2 02U 0254 116 000 1.16 723 0.77 3.3 0,0020 15.3 15 2.5 116 076 4405 O20 43.82 46.70 85 0.9 001 1.38 1.16 0,025 0.2 0.1 424 426 (2.71) (265) 273 1.02
DI-2 DI-3 0218 0.472 1.10 076 1.92 7,23 017 45 0.0025 165 18 32 08 046 43.0 022 4325 MS2 75 0.7 0.01 1,31 1.10 0024 02 0.1 422 424 (2.55) (2.61) 3.35 1.39
01-3 DI-4 0298 0770 0% 1.22 2.37 723 0.n 80 00025 20.5 21 38 IN 0,50 4290 027 4263 4638 110 3" 003 IA5 0% 0022 02 04 41A 422 (247) (246) 348 1.27
014 DI-5 0.129 0.099 IAA 1.71 2.87 723 On 106 0W25 227 24 39 60 0.28 42.28 0.17 42.12 45.85 90 1.2 O.Ot 1,32 1.10 0.021 02 00 41.8 41.9 (2.37) (237) 3,57 IAA
DI-5 DIE 0008 0,985 081 1,99 3,15 7.23 077 11.1 ODIN ITS 24 78 178 0.38 4202 1.78 40.24 45.50 73 14 002 0.97 081 0021 02 DO 41.3 418 (089) (2.27) 348 1,02
DIE MH4 0802 1.787 1.57 2,37 3.53 723 On 156 00150 187 24 Its IN OAS 40,14 162 38,52 4325 150 23 0.02 1.85 1.57 0.021 0.2 0.0 40.8 41.3 031 (079) 361 1AS
MH-1 1411-2 0." 1.787 OW 2,37 3.50 723 077 156 0.0035 22A 24 6.1 S4 0,25 38,42 0.33 360E 42.W 0012 02 0.0 40.5 408 045 041 3.58 1.12
MH-2 POND 0000 1977 OW 256 372 7.23 0.77 16.5 0.0035 238 24 61 272 0,74 3799 0.95 3704 42.00 0.012 0.2 1.0 390 40.5 (0.04) 0.55 40, 1,55
POND MH-3 0.000 SO 0.0025 USA 24 52 70 0,22 33,75 0.18 33.58 4GOO 0012 02 00 28.1 282 (7,45) (7,67) 625 3,79
MH-3 MH4 0ON 12.1 ODIN 165 24 104 331 0,53 31DS 3.31 27.78 36.33 0012 0.2 0.0 27.6 20.1 (2.17) (4.97) 524 2,78
MH4 MH-5 ONO 12.1 ODIN - 166 24 10.4 246 0.39 2768 2.46 2522 32,10 0.Ot2 02 0.1 272 276 (002) (207) 442 1.98
MH-5 MHE 00W 12.1 001W 165 24 104 266 0,43 25.12 2W 2246 30.25 0.0 t2 02 0.1 0.0 OA (24.46) (26.68) 5.13 267
MHE MH-7 OWO 12.1 0.01W 165 24 10A 15 002 2236 0.15 22.21 2945 0.012 0.2 1 CA 27.1 27,21 289 2.84 7.09 4.63
D67 ad 0.020.: 0.020 027 ON 0.27 7.23' 'Dn '0.1 0.0075 3.0 - 8 32 .581.. 029 40.38 0d2 39.W M50 n 2.0 DOE` ,n DU 027' OD17 023 0.0: 40,8 4G.81-0.21. (021)1 4.12 ..2.99
CPS 01.9 0084 SAN 0.96 0.29. 0.95 723 'O.n O6I' "OW75 56 "8' 32 86b 044 39.66 ,064 3923.. 47.45 -W. 05 0.01"" 115 `096 O.Oi7 ' 02 " -00 407 408 -6.84 -031 7.W ,846,
DF9 01-10" 0O45 OfA9 -0.47 072 1:4D 723 0,77., 08 0W75 64 0 33 "Ss- 018 '39,13 O2Ix W.W 4445 .W: 17 DOS O.W. 047'. 0,017 ` 02 03 4 ,S 407 1..08 n094" 5.32 420=
Db10 MH-2' '0.041 0.190 027 091 1.59 723 .:O.n 1.1 OW50 SA 12 3.5 '87 -0.32 "38.42 0U, 8809= 000 35 - 23 001- 034 027;, 0.027 03'- 0.6 405 ',40.6 '1i45 1.18= '5,58 '4.12:
DI-iF DI-2F 0,03 0.03 3.89 GDO 3.83 7.23 0,20 0.9 0.W25 6.1 12 25 55 0.37 32 So 0.14 32.36 34.75 421 5.5 D.01 4.35 3,83 0.015 0.2 CO 28.9 28.9 (4,51) (462) 225 079
DI-2F DI-3F ams 1.198 3.01 0.37 420 713 020 1.7 0,0025 10.3 12 2.5 55 0.37 32.26 0.14 32.13 34.75 41] 54 0,01 4.34 3,81 0.015 0.2 00 288 2tl9 (4,35) (4.41) 2.49 T03
DI-3F D14F 0.575 1,773 3.73 0.75 457 723 020 26 0.W25 12.0 12 2.5 55 0.37 3203. 0.14 31,89 34.75 417 51 0.01 425 373 0,015 0.2 0.1 286 288 (4,30) (425) 273 127
D14F MH-3 1020 2.793 352 1.12 4.95 723 020 40 0.W25 14.2 IS 28 139 0.01 31.54 035 31.19 34.75 415 6.5 0.02 401 3.52 0,014 0.2 1.0 28A 28.6 (4,32) (420) 3.21 1.SO
,1dl St D-51' 42 IS 33,55
D-5F DI-9F 0.5132 0.502 3.71 0DO 371 723 025 5.1 0M50 152 18 4.5 50 0.21 3250 029 32,21 3V5 418 58 0,01 423 371 0,024 02 00 31.3 31.5 (2.36) (251) 2.25 029
DI-61' DI-7F 0351 0M3 114 021 1.24 723 025 15 0.0050 8.7 12 3.S 24 0.12 39.50 0.12 3238 34.SO 93 1.D 001 IA7 124 0015 02 00 28.9 2891 (4.50) (459) 2,30 0,84
DI-7F DI-BF 0.526 1.379 345 0.33 393 7.23 0.25 6.7 00350 168 18 4.5 57 021 32,11 029 31.33 34.75 361 43 001 3W 345 0.024 02 00 31.1 313 (222) (2.26) 2.64 0.68
DI BFDI-9F 0395 1.174 1.BE 054 4A4 7.23 0.25 7A O.WW 174 18 45 62 023 31.73 031 3142 0415 205 3.9 002 2.18 1.86 0024 02 0.1 30.8 31.1 (2.15) (2.12) 303 1,07
DI-9F SOMH 0203 2.305 1,37 076 4,36 7.23 025 84 OWW 18.2 21 5.0 61 020 3107 031 30.76 34.75 151 3.3 0.02 162 137 0.022 02 04 305 SO (201) (2.05) 369 1.48
DF10F DWF -0,IN 029D `'1.02 -0W- -1.02 7.23 -917 08- -OWW 6.7 12 3.5 - 65 " -0.31 32.W D.33 39.18 34W 79 10- ;0.0, 1,21 I0W ;0027 0.2 ,DO 11.4 31.5 (1.75) (2.D4) 2.30' 0.84
DF11F DI-9F 0.038 U32 % 0,31-. 'in 723 D17 09- 0005) 10 12 35 32 0.15 32.W DA6 31.92 31W 82 " 06 0.01 1.16 ON DW 02 03 SIA 31.4 (1.52) (1.65) 2.73 1.27
DI-12F DI-13F 0.n5 W GOO 164 723 037 09 0M25 8A 12 25 139 0.94 32.75 035 32AO 34.SO 118 10 001 1.93 164 0027 02 0.1 3C5 305 (290) (3.17) 205 0.59
DI-13F SDMH 0576 A4 C94 2,59 7.23 0.37 2A 34.80 67 t0 001 1.35 1.14 W.5 W.5
x-axmaiO,�v�s--mow+- +n„ev�rne_uwa.

STORM DRAINAGE DESIGN DATA SHEET
Pt.p W. Dale: L11M r
Roj tl SIM: 2012
Stearn Freyu
1 2
Loulbn
Rcrn To Ctiet 0 late,-N
OOE DI-1
C -12 DI3
cO 24 01-4
C0.14 DI-8
0O15 DI-9
DI-1 01-2 ZS 4.3
DI-2 DI-2 11.3 6.8
6I-3 014 15.9 1.8
04I DI-5 21A 10.8
DI-5 DIE 21.4 10.3
OIE MH-1 21A 5.8
N- MH-2 21.4 5.8
M11-2 POND 21A 2,9
POND MH-3 21.4 136
MH-3 MHJ 21.4 93
MH-4 MH-5 21.4 9.3
MH.S MHE 21A 9.3
MHE MH-t 21.4 9.3
1.91' 'R.B.
DIE" D 9 19 1.4'
069"'OHO 1.9 1.1:'
OHO 'MH-2 /6 -3.6;
DI4F DI-2F 4.6 3.7
DI-2F DI-3F /6 2.9
DI-3F 014F 46 2.1
04IF MH-3 7.5 3.5
110 St DSF
PSF DI-9F 11.3 6.1
DL6F DI-4F 46 3.1
D17F DldF 116 4.6
IMF DI-9F 11,3 3 0
DI-9F SDMH 159 7.5
ETIOF :D411F .4.6 3.9
DT11F :OI-9F
51-12F D443F l6 it
DL13F SDMH
vwro�ptonvrs_u.i_wgw..am�ur�M1�+_uw�ee

STORM DRAINAGE DESIGN DATA SHEET Yea
Rgeq W.: 018041003 DmiMea By: 0.G Ome: v17A0 Ropa Num j. D1804]00] De IWW By: aG
Pmpa: mii, n WOde SCmd Mocked By: sneel 1 02 Ro,i NlRnim Middle saved Uecke09y: n Or,
Siwm FneOuervy', 5OYert R9e Type: RCP mVWe: 0.012 2.,244m rsmhA: 4.5 5ebee mVWe: 0011 Ca OW
1 2 1 ] 1 4 5 1 6 1 ] 1 8 1 9 10 11 12 13 14 15 IS 17 717 7 20 L 6 7L
Laalbn ArY %PE DATA PRAMEMRIN WTA IIym.GeY llry Mtlnle ab�a9.e. (QVe
SW Not Rpe U 1 C Min.P,m Semen US To W DS US Ran fie., fi'M' 6�n
From To TOW Tolel Tom9 Tome Tine of mammy RunoB 061N Slcpe Sia Slxe VhR LapN Tome orvM Ppe F4 1. Top S. Lm9N Hd9M Sl.0 RRa 8M I ZB U OZB OU Gesb eblgm
(saa) (eaal Ilan) (dn) On.W.) Cues. lael Inml On) M0 IN41 Oedl 1�1 16) 18) 18) 18) In.l (61 Inm.l (nn) Fa lO�l Imvn and
PP
COE 01-1 0.287 0.287 8.a7 ON 2.3
CO-12 01-3 0287 0287 887 ON 23
CO-24 DIJ 0.287 0287 a87 ON 2.3
CO-14 DI-8 0.105 0.105 887 ON 0.8
00-15 DI-9 0191 0.191 887 ON 15
DI-1 01-2 0.2U 0254 146 ON till 887 077 40 0.0020 16.5 15 2.5 116 076 M.05 023 4382 48.]8 85 0.9 0.01 1.33 1.16 0.025 02 0.1 44.1 44,5 (1011 (081) 2,73 102
01-2 DI-3 0,218 OA]2 1.%0 076 1.92 8.87 0.77 5.5 0.0025 178 10 3.2 Ba 0.46 43.47 0.22 4325 46.92 75 0.7 001 131 1.10 0024 02 0.1 43.8 M. (0.91) (0.91) 3,35 1.39
DI-3 DIJ 0298 0.770 095 122 2.37 0.87 0.77 9.8 0.W25 221 21 3.6 IN 0.W 42.M 021 4263 I6,U 110 3.1 003 1.15 0.% 0022 0.2 0.1 43A 438 (IN) (0.94) 3,48 1.27
DIJ DI-5 0,129 080 1.10 17I 2.87 8.87 077 130 0M25 245 24 3.9 66 028 42.28 0,17 42,12 4585 W 1.2 001 1.32 1.10 0021 0.2 00 43.1 43A (090) (0SO) 3,57 1.11
01-5 DIE DOW 0.985 0.81 1.99 315 887 037 138 O.OIW 19.2 24 7.8 17B 038 4202. 1.78 4024 45.50 73 1A 002 097 081 0021 0.2 00 42.5 43.1 0,29 (0 SS) 3.48 1.02
DIE MH-1 0.002 1,787 157 237 3.53 8.87 0.7] 19.1 0.0150 202 24 9S IN 0.19 40.14 1.62 3852 43]5 1W 2.3 002 1.85 1.57 0.021 02 0.0 411 425 123 0,39 3.61 1.15
MH-1 MH-2 0.NO 1]8] 0.00 2.37 3.53 8.87 077 191 0W35 23.9 24 6.1 9t 025 3842 033 3809 42M 0012 02 0.0 41.3 41,8 122 133 3.58 142
MH-2 POND 0.NO 1,977 0.DO 256 3.72 8.87 0.77 22.7 0.W35 255 24 &1 272 0.74 37.99 0,95 37.04 4200 0012 02 1.0 39.0 41.3 (0.04) 1.32 4,01 1,55
POND MH-3 0" 8.0 0.0025 IOA 24 52 ]0 022 33.75 0.10 1158 4D.00 0012 0.2 00 283 28.3 (TW3 (741) 625 379
MH-3 MHJ OWO 13.0 0.01M 17.0 24 10.4 331 053 31.09 3,31 2778 Wn 0.012 0.2 00 27.7 28.3 (2.09) (I8D 524 22a
MH-4 MH-5 0NO 13.0 D.0100 17.0 24 104 246 039 27M 246 25.22 32.10 0012 02 0.1 272 273 (0.01) (1.99) 442 1.96
MH-5 MHE 0.OW 13.0 0.01M ITO 24 104 2W 0.43 25,12 2.66 22.0 W,25 0,012 0.2 D.1 0.0 0.5 (24.46) (2661) 5.13 2.67
MHE MH-7 0ON 13.0 00100 170 24 10.4 15 002 22,M 0,15 22.21 2945 0,012 0.2 0.1 27.1 27,2 289 205 7,09 463
D67 DI-8` '0.020d. .0020 027 .0.00:. ::027.: r.88'7 O.TI 0.1 "0.Wn 32 '' 8 '32 -Ral 029: ,40W 042 '3996 .M W 33.. .2.0. ON 0.0 :0.2]S 0.017 "02 0.0 41.8 41.8 "1d4 0.72' '4.12 2.99-
D48 DI-9 '0084' AN ON On ::0.% 687 : 0." 07 0W75 60 8 32 85` 0+1 '3RW 061 M," 4 45 SO :OS 001. 115 ON, 0017 _02 00 41.6 41.8 Y]2 1,24: 7.59 646
D1,9 OG10"10.045' 0.149 0.47 0.72 e1.40 887 : :O]7 10, 000]S 69 18 32 '36' 010 "39.13' '027' WAS M45 SO .17 0.03 ':OW. OAT: 0017 02 0.3 41.4 41.6 190 182 "5.0 420-
0I-f0 MH-2"0041' 0.190' '027 091 "1:N aU : :0.77 1.3 .O NN 9.1.:. :. 12 35 87 632 U42 `0.34 3909 M00 -'35= 23 0.07- ::O.0 >0.27. 0.027 02 0.5 41.3 41.4 2.22 200 5W 4,12
DI-IF DI-2F 0.fin 0633 383 000 303 887 0.20 1.1 0W25 0.8 12 25 55 0,37 32.50 0.14 32,W 34.75 421 55 001 435 3.83 0015 02 QO 29.4 294 (3.98) (4.08) 2,25 0.79
DI-2F DI-3F 0565 1.198 381 0.37 4.20 8,87 0.20 2.1 OW25 11.2 12 2.5 55 0.37 3226 0,14 32.13 U35 417 5A 0.01 434 3.81 0015 02 00 29.3 294 (3.96) (30) 249 103
DI-3F D14F 0.575 1.T73 3,73 075 457 S87 020 3.1 0.W25 12.9 12 25 55 0,37 32.03 0.14 31.89 04.75 417 5.7 001 425 0.73 0.015 02 01 29.0 29.3 (391) (0.76) 273 127
DNF MH-3 1020 2.793 352 1.12 4.95 a.87 020 50 0M25 15.3 15 20 139 0.81 31.54 0.35 31.19 U75 415 65 0.02 4.01 3.52 0.014 0.2 LO 20.3 29.0 (4.16) (381) 3.21 1.W
1181 St D-5F 42 15 3355
65F D47F 0.502 O.W2 3.71 OW 371 887 025 5.3 ON50 154 18 45 58 021 U250 0.29 3221 OU5 418 5.3 001 423 371 0024 02 OD 31.5 31.7 (2.18) (232) 225 029
DIEF DNF 0.351 0,853 1,24 0.21 124 887 025 1.9 OOOW 94 12 35 24 0,12 32.50 0.12 32,M M80 93 10 001 147 124 0015 0.2 OD 29.4 29.5 (3.96) (4.03) 2.30 081
01-7F DI-OF 0,525 1379 345 0.03 393 0.87 0,25 7.3 OWN 173 1S 45 57 021 32.11 029 3183 M.75 M1 45 001 3.94 345 0.024 0.2 00 31.2 31.5 (2.09) (2.08) 2.64 0.OR
DIEF DI-9F 0395 1.774 1.86 0.51 4,14 8.87 025 8.1 OWN 10.1 18 4.5 62 023 31.73 031 31A2 U75 206 3.9 0.02 2.10 185 OON 02 0.1 W8 312 (209) (IN) 3,03 107
01-9F SDMH 0.203 2.305 1.37 0.76 4M 887 025 93 CW50 19.0 21 5.0 61 020 3107 0.31 W.76 N.75 151 3.3 0.02 1.62 137 0022 02 04 W5 308 (201) (199) 369 148
DY1U JFO.4�05 -0ZBD.: -102 , OAO 1,02 : 6,87 -03] 1.0 D.O050 7.3 "12 38 ?65 0,31 32W 03J n.18: UW 79, f0 0.01 1.21 S1.02 OOV 0.2 00 '314 ':P:5 '(1.74) (202J 2.301111F 0328a0960.31 : 133 - 6.87 D.37' Li O.00W 76 '12 35 '-32• "0.15 3208 016 31.92J 31W 62: 06 . 0.01 116 0.% 0027 D2. 03 314 31A "(152): (tU) 2T3`" 127
DI-12F0.510.DO 16`1 887 037 1.1 OW25 a.7 12 25 139 0.94 32.75 0,35 3240 UN 118 1.0 0.01 1,93 1 W 0027 02 0.1 30.5 WA (2.90) (3,13) 205 0.59
01-13F 0.911 1.14 0,94 2.59 687 037 30 1 U'SO 97 1.0 0.01 I'M 1.14 30.5 W.5
cNxa4wrOlu>•un-wwuwe- +amvaw-orw•w

STORM DRAINAGE DESIGN DATA SHEET
Pmjm* SM1-L 2o12
6 Fr"
1 2
From To CA B m.o..
co:F
C612 DI-3
-6624 D"
CO to DI-5
-C&i5 DI-9
DI-1 01-2 75 3,5
01-2 01-3 113 57
DI-3 D" 15.9 60
D14 DI-5 21.4 84
—(Tl--5- D141 214 TO
oi:i- MH-1 1 214 1 23 1
WH-1 MW2 21A 23
—- --KAH.2 P- OND 21A 1 (14)
POND MK-3 214 13,3
MH-3 MHO 21A BA
MH4 MH-5 21A 0.4
WH-5 MH4 214 0A
-WHT MH-7 21.4 5A
I'a
-5F10 MI+2 �46 - 13-
-61 IF DI-2F 4.6 35
DI-2F DI-3F 46 25
-01--3F D"F 46 15
-614F MH-3 7.5 26
Tl 0 St 0.SF
-0.5F DL7F 11.3 59
-614F 014F 46 27
-il--7F D-OF 113 40
-UBF DI-9F 11.3 3.1
-01-9F SDMH ISO 15'5
5710F OF111` 46 17
DI-IIF DI-13F
-El 12F DI-13F 40 3,5
Ul 13F SOMH

Kimley-Horn 5n/00
and Associates, Inc.
Sheet No. 1 0!2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/16/00 Checked by Date
Design Post Development Discharge Rate To Equal Pre-Development Discharge Rate for the 10-year storm event
Hydrograph Formulation
1.) Estimate Peak
Watershed Area = 3.11 acres
C = 0.2
1 = 7.23
A = 3.11
Qpre = 4.49706
Post Development Discharge Rate Determination, Q p�,
QT.11n
(cfs)
18.48
2.) Estimate Volume of Run-off
Use 10-year design storm, 6 hour duration. Depth = :4.8 �`v inches
Pre Devel. Soil Storage Capacity, S = 1000/CN-10 = 4.49 where CN = ;69
Pre Devel. Run-off, R=( P -0.2 S)2/( P+0.8 S) P = 4.8
Post Devel. Soil Storage Capacity, S= 1000/CN-10 = 1.14 where CN = 90
Post Devel. Run-off, R=( P-0.2 S)Z/( P+ 0.8 S) P = 4.8
3.) Set the shape of the hydrograph
Pre Devel. Time to Peak, Tp= 43.5 .Area 'Runoff = NIA min.
Qpre10
Post Devel. Time to Peak, Tp= 43.5 'Area ' Runoff
Qpost10
4.) Estimate the Required Storage, S
S10=(Qpost-Qpre) x Tpl Opost x 1.39 x 60= 41,317 CF
5.) Hydrograph Formulation
r:k%Williston Deten_Pond Arev-4.xls 10•Year Hydrograph

Kimley-Horn 5/1/00
and Associates, Inc.
Sheet No. 2 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3116/00 Checked by Date _
Discharge(Q)
Time(t)min. Post Time Increment= . ,011, "Tp
0 0.00
2.68 0.45
5.36 1.76
8.04 3.81
10.72 6.38
13.41 9.24
16.09 12.09 10-Year Storm Event Inflow Hydrodraph
18.77 14.67
21.45 16.71 tPost Devel Inflow f-Pre Devel Inflow
24.13 18.03
26.81 18.48 20
), a 4 vYw
29.49 18.03n, ' '
a
18 ,5 A � , r :"z r' as my .tx .
32.17 16.71 ' w, aA�da54 v a .
34.85 14.80 16 h k�rnxa
37.54 12.99 ti ,
40.22 11.41 14 .' `
42.90 10.02 12 �
45.58 8.80 p
48.26 7.72 lawm 10 .• u ea
� '. .
50.94 6.78 A Olt
53.62 5.96 0 8
56.30 5.23 :
58.98 4.59 6
61.67 4.03 4 . „ h
64.35 3.54 -' s
67.03 3.11 2
69.71 2.73 > i
72.39 2.40 02
75.07 2.11 0 20 40 60 80 100 120 140
I
77.75 1.85 Time,t(min)
80.43 1.62
83.11 1.43
85.80 1.25
88.48 1.10
91.16 0.97
93.84 0.85
96.52 0.74
99.20 0.65
101.88 0.57
104.56 0.50
107.24 0.44
109.93 0.39
112.61 0.34
115.29 0.30
117.97 0.26
r:\\Williston_Deten_Pond_Arev-4.xls 10-Year Hydrograph

Kimley-Horn s/voo
and Associates, Inc.
Sheet No. 1 0/2 -
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
Design Post Development Discharge Rate To Equal Pre-Development Discharge Rate-50-year storm check
Hydrograph Formulation
1.) Estimate Peak
Watershed Area = 3.11 acres
Post Development Discharge Rate Determination, Qp,,,t
QTa,SII
(cfs)
22.67
2.) Estimate Volume of Run-off
Use 25-year design storm, 6 hour duration. Depth = t''6.40 :', inches
Pre Devel. Soil Storage Capacity, S= 1000/CN-10 = 6.67 where CN = 60'.
Pre Devel. Run-off, R=( P -0.2 S)2/( P + 0.8 S) P= 6.4
Post Devel. Soil Storage Capacity, S= 1000/CN-10 = 1.14 where CN = 90
Post Devel. Run-off, R=( P -0.2 S)2/( P+ 0.8 S) P = 6.4
3.) Set the shape of the hydrograph
Pre Devel. Time to Peak, Tp = 43.5'Area ' Runoff = N/A min.
Qpre50
Post Devel. Time to Peak, Tp= 43.5 'Area ' Runoff
Qpost50
4.) Estimate the Required Storage, S
S5o=(Qpost-Qpre)x Tp50post x 1.39 x 60 = 58,811 CF
5.) Hydrograph Formulation
r:\\Williston_Deten_Pond_Arev-4.xls 50-Year Hydrograph

Kimley-Horn 5/1100
and Associates, Inc.
Sheet No. 2 0/2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Desianed by AJG Date 3/17/00 Checked by Date
Discharge(Q)
Time(t)min. Post Time Increment= : 0:1 a, 'Tp
0 0.00
2.68 0.41
5.36 1.62
8.04 3.54
10.72 6.02
13.41 8.90
16.09 11.94 50-Year Storm Event Inflow Hydrolaraph
18.77 14.95
I
21.45 17.69 Post Devel Inflow t Pre Devel Inflow j
24.13 19.97
26.81 21.62 25
29.49 22.52 .E„ ��
32.17 22.60 �#
wt <
34.85 21.87 20 � Ae
37.54 20.36
}
40.22 18.32 �; a
42.90 16.38 15
45.58 14.64
48.26 13.09 ; .. IM IN FA M In,I
50.94 11.70 i "N
53.62 10.46 m 10
56.30 9.35 a1
58.98 8.36 3
61.67 7.48 5 /
64.35 6.68 7
67.03 5.98 "
69.71 5.34 0r 16
72.39 4.78
75.07 4.27 0 20 40 60 80 100 120 140
77.75 3.82 Time,t(min)
80.43 3.41
83.11 3.05
85.80 2.73
88.48 2.44
91.16 2.18
93.84 1.95
96.52 1.74
99.20 1.56
101.88 1.39
104.56 1.24
107.24 1.11
109.93 0.99
112.61 0.89
115.29 0.80
117.97 0.71
r:\\Willjston-Deten-Pond-Arev-4.xls 50-Year Hydrograph

Kimley-Horn 5i1100
and Associates, Inc. Sheet No.1 of 1
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3116100 Checked by Date
Stormwater Pond Volumes(Average End Method)
EL Z Forebay Pond Forebay Combined
Area Volume Area Volume % Area Volume
(sf) (cf) (sf) (cf) (sf) (cf)
33275 4 Oi00 6° 0 3450 0 0% 3,450 0
0.25 497. 62 3 632 885 7% 4,129 947
53 1.25 1,067 844 *384 4,893 —1'5% — 5,451 5,737
36:00' ° 2.25 1,697 2,226 6;067 10,119 18% 7,764 12,345
31.00: ` 3.25 2;381 4,268 ,989 17,147 20% 10,375 21,414
,37
-25,:25 3.50 2567 4,887 81246 19,176 20% 10,813 24,063
38tA� 4.25 0% 12,404 32,804
5.25 0% 13,723 45,867
40:00 6.25 0% 15,098 60,278
Williston Deten Pond Arev-4.xlsTond Volumes

Kimley-Horn 5/1/00
and Associates, Inc. Sheet No.t of 1
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
designed by AJG Date 3/17/00 Checked by Date
Stage-Storage Function Calculation
Area Incr Vol Accum Vol(S) Stage (Z) Elev In(Z) In(S) Z est.
(sf) (cubic feet) (cubic feet) (feet) (feet)
10,813 24,063 3.50 37.25
12,404 8,706 32,769 4.25 38.00 4.24
13,723 13,064 45,833 5.25 39.00 1.658 10.733 5.25
15,098 14,411 60,243 6.25 40.00 1.833 11.006 6.25
Stage-Storage
log-log plot
11.0 ,
10 9 `
+Stage Storage
10.9
108 a �
K ti to
10.8 Y
10.7 > / Halo
. t _
1.6 1.7 1.7 1.8 1.8 1.9
In Z
Determine Stage-Storage Parameters From S= KSZ° >>> Z= (S/Ks)"b
Linear Regression Analysis ( y = a + bx)
b= 1.568032
a= 8.132600 Ks = (ea) = 3404
r= 1.000000 r2= 1.000000
Williston_Deten_Pond_Arev-4,zls\Stage-Storage

Kimley-Horn 5/1/00
and Associates, Inc. Sheet No. 1 of 3
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/16100 Checked by Date
Stage-Discharge Function
Device Variables
Orifices
CD Dia A g h invertfinlet site
(ft) (Sq. a) (R/secz) (ft) elev elev
11/2" orifice 0.60 0.1250 0.0123 32.2 Z- D/2 3.50 37.25
Riser 0.60 2 X 2 4.00 32.2 Z- D/2 4.25 38.00
Barrel 0.59 1.00 0.79 32.2 Z- D/2 0.00 33.75- -
Weirs (trapezoidal) Q=CwLH32+2.44SSH2.5 where SS = sideslope (h/v)
Cw L H h v SS Crest Elev
(re) (R) (R) (R)
Riser 3.33 12.00 Z-Crest Elev 4.25 38.00
Emergency 3.0 20 varies 3 1 3 5.25 39.00
Elev Stage 11/2"orifice Riser Riser Barrel Principal Emergency Total
(Z) (orifice) (weir) (orifice) (orifice) Outflow Weir Outflow
(ft) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
37.250 3.500 0.000 0.0 0.0 0.0 0.0 0.0 0.0
37.375 3.625 0.015 0.0 0.0 0.0 0.0 0.0 0.0
37.500 3.750 0.026 0.0 0.0 0.0 0.0 0.0 0.0
37.625 3.875 0.033 0.0 0.0 0.0 0.0 0.0 0.0
37.750 4.000 0.039 0.0 0.0 0.0 0.0 0.0 0.0
37.875 4.125 0.044 0.0 0.0 0.0 0.0 0.0 0.0
38.000 4.250 0.049 0.0 0.0 0.0 0.0 0.0 0.0
38.125 4.375 0.053 1.8 6.8 7.3 1.8 0.0 1.8
38.250 4.500 0.057 5.0 9.6 7.4 5.0 0.0 5.1
38.375 4.625 0.061 9.2 11.8 7.6 7.6 0.0 7.6
38.500 4.750 0.064 14.1 13.6 7.7 7.7 0.0 7.7
38.625 4.875 0.068 19.7 15.2 7.8 7.8 0.0 7.8
38.750 5.000 0.071 26.0 16.7 7.9 7.9 0.0 7.9
38.875 5.125 0.074 32.7 18.0 8.0 8.0 0.0 8.0
39.000 5.250 0.077 40.0 19.3 8.1 8.1 0.0 8.1
39.125 5.375 0.080 47.7 20.4 8.2 8.2 2.7 10.9
39.250 5.500 0.082 55.8 21.5 8.3 8.3 7.7 16.0
39.375 5.625 0.085 64.4 22.6 8.4 8.4 14.4 22.8
39.500 5.750 0.087 73.4 23.6 8.5 8.5 22.5 31.0
39.625 5.875 0.090 82.8 24.6 8.6 8.6 31.9 40.5
39.750 6.000 0.092 92.5 25.5 8.7 8.7 42.5 51.3
39.875 6.125 0.095 102.6 26.4 8.8 8.8 54.4 63.2
40.000 6.250 0.097 113.0 27.2 8.9 8.9 67.3 76.2
40.125 6.375 0.099 123.8 28.1 9.0 9.0 81.4 90.4
40.250 6.500 0.101 134.9 28.9 9.1 9.1 96.6 105.7
40.375 6.625 0.103 146.3 29.7 9.2 9.2 113.0 122.2
Williston_Deten_Pond_Arev-4.xisGStage•Discharge

Kimley-Horn 5/1/00
and Associates, Inc. Sheet No.2 of 3
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/16/00 Checked by Date
40.500 6.750 0.105 158.0 30.5 9.3 9.3 130.4 139.7
40.625 6.875 0.108 169.9 31.2 9.4 9.4 148.9 158.3
40.750 7.000 0.110 182.2 31.9 9.5 9.5 168.6 178.0
40.875 7.125 0.112 194.8 32.7 9.6 9.6 189.3 198.9
41.000 7.250 0.113 207.6 33.4 9.7 9.7 211.1 220.8
41.125 7.375 0.115 220.7 34.0 9.8 9.8 234.0 243.8
41.250 7.500 0.117 234.1 34.7 9.8 9.8 258.1 267.9
41.375 7.625 0.119 247.8 35.4 9.9 9.9 283.2 293.2
41.500 7.750 0.121 261.7 36.0 10.0 10.0 309.5 319.5
41.625 7.875 0.123 275.8 36.7 10.1 10.1 336.9 347.0
41.750 8.000 0.124 290.2 37.3 10.2 10.2 365.4' 375:6--
41.875 8.125 0.126 304.8 37.9 10.3 10.3 395.1 405.3
42.000 8.250 0.128 319.7 38.5 10.4 10.4 425.9 436.2
42.125 8.375 0.130 334.8 39.1 10.4 10.4 457.8 468.3
42.250 8.500 0.131 350.1 39.7 10.5 10.5 490.9 501.4
42.375 8.625 0.133 365.7 40.3 10.6 10.6 525.2 535.8
42.500 8.750 0.135 381.5 40.9 10.7 10.7 560.6 571.3
42.625 8.875 0.136 397.5 41.4 10.8 10.8 597.2 608.0
42.750 9.000 0.138 413.7 42.0 10.8 10.8 635.0 645.9
42.875 9.125 0.139 430.1 42.5 10.9 10.9 674.0 685.0
43.000 9.250 0.141 446.8 43.1 11.0 11.0 714.2 725.2
43.125 9.375 0.142 463.6 43.6 11.1 11.1 755.6 766.7
43.250 9.500 0.144 480.7 44.1 11.2 11.2 798.3 809.4
W Iliston_Deten_Pond_Arev-4.xlsGStage-Discharge

Kimley-Horn 5/1100
and Associates, Inc. Sheet No.3 of 3
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/16100 Checked by Date
Individual Device Stage-Discharge Plot
10.0
9.0
aqll
8.0p .. N Pipe
--
1 - b�.' .. i
a
7 0 �- Riser (weir)� '' : � is
M 4 Riser (orifice)
6.0 F Barrel i
5.0 rf;
I I I I
0 50 100 150 200
Discharge (cfs)
Composite Stage-Discharge Plot
10.0
9.0 r
$ 8.0 t -
—PrincipalOverflow!
iV —F Emergency Weir
a Total Outflow
I
5.0 '
4.0
0 200 400 600 800 1,000
Discharge, Q (cfs)
Williston_Deten_Pond Arev-4.xlstStage-Discharge

Kimley-Horn 5/1/00
and Associates, Inc. Sheet No.1 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
10-Year Event Chainsaw Routing Max. Elev. = 38.93 Max. Disc. = 8.05 cfs
1112" Principle Emergency
Time Inflow Storage Stage Elev Outflow Pipe Outflow Weir
(min) (cfs) (cu-ft) (ft) (cfs) (cfs) (cfs) (cfs)
0.00 0.00 24,063 3.50 37.25 0.00 0.000 0.00 0.00
2.68 0.45 24,063 3.48 37.23 0.00 0.000 0.00 0.00
5.36 1.76 24,136 3.49 37.24 0.00 0.000 0.00 0.00
8.04 3.81 24,419 3.51 37.26 0.00 0.000 0.00 0.00
10.72 6.38 25,032 3.57 37.32 0.01 0.005 0.00 0.00
13.41 9.24 26,058 3.66 37.41 0.02 0.019 0.00 0.00
16.09 12.09 27,542 3.79 37.54 0.03 0.028 0.00 0.00
18.77 14.67 29,482 3.96 37.71 0.04 6.037 0.00 0.00
21.45 16.71 31,836 4.16 37.91 0.05 0.046 0.00 0.00
24.13 18.03 34,518 4.38 38.13 1.96 0.053 1.91 0.00
26.81 18.48 37,102 4.59 38.34 7.52 0.060 7.52 0.00
29.49 18.03 38,865 4.73 38.48 7.64 0.064 7.64 0.00
32.17 16.71 40,535 4.85 38.60 7.76 0.067 7.76 0.00
34.85 14.80 41,975 4.96 38.71 7.86 0.070 7.86 0.00
37.54 12.99 43.092 5.05 38.80 7.93 0.072 7.93 0.00
40.22 11.41 43,906 5.11 38.86 7.98 0.073 7.98 0.00
42.90 10.02 44.458 5.15 38.90 8.02 0.074 8.02 0.00
45.58 8.80 44,779 5.17 38.92 8.04 0.075 8.04 0.00
48.26 7.72 44,901 5.18 38.93 8.05 0.075 8.05 0.00
50.94 6.78 44,850 5.18 38.93 8.04 0.075 8,04 0.00
53.62 5.96 44,647 5.16 38.91 8.03 0.075 8.03 0.00
56.30 5.23 44,314 5.14 38.89 8.01 0.074 8.01 0.00
58.98 4.59 43,867 5.11 38.86 7.98 0.073 7.98 0.00
61.67 4.03 43,322 5.06 38.81 7.94 0.072 7.94 0.00
64.35 3.54 42,692 5.02 38.77 7.90 0.071 7.90 0.00
67.03 3.11 41,990 4.96 38.71 7.86 0.070 7.86 0.00
69.71 2.73 41,227 4.91 38.66 7.81 0.069 7.81 . 0.00
72.39 2.40 40,410 4.84 38.59 7.75 0.067 7.75 0.00
75.07 2.11 39,549 4.78 38.53 7.69 0.065 7.69 0.00
77.75 1.85 38,650 4.71 38.46 7.63 0.063 7.63 0.00
80.43 1.62 37,720 4.64 38.39 7.56 0.061 7.56 0.00
83.11 1.43 36,765 4.56 38.31 7.00 0.059 6.94 0.00
Williston_Deten_Pond_ArevA.xls\Chainsaw Routing 10-Year

Kimley-Horn 5/1/00
and Associates, Inc. Sheet No.2 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
10-Year Event Chainsaw Routing Max. Elev. = 38.93 Max. Disc. = 8.05 cfs
1112" Principle Emergency
Time Inflow Storage Stage Elev Outflow Pipe Outflow Weir
(min) (cfs) (cu-ft) (ft) (cfs) (cfs) (cfs) (cfs)
85.80 1.25 35,867 4.49 38.24 4.76 0.057 4.70 0.00
88.48 1.10 35,303 4.44 38.19 3.49 0.056 3.44 0.00
91.16 0.97 34,918 4.41 38.16 2.71 0.055 2.65 0.00
93.84 0.85 34,638 4.39 38.14 2.18 0.054 2.12 0.00
96.52 0.74 34,424 4.37 38.12 1.80 0.053 1.74 0.00
99.20 0.65 34,254 4.36 38.11 1.52 0.053 1.46 0.00
101.88 0.57 34,116 4.35 38.10 1.30 0.052 1.24 0.00
104.56 0.50 33,999 4.34 38.09 1.12 0.052 1.07 0.00
107.24 0.44 33,900 4.33 38.08 0.98 0.052 0.93 0.00
109.93 0.39 33,813 4.32 3&07 0.86 0.052 0.81 0.00
112.61 0.34 33,737 4.32 38.07 0.76 0.051 0.71 0.00
115.29 0.30 33,670 4.31 . 38.06 0.68 0.051 0.63 0.00
117.97 0.26 33,609 4.31 38.06 0.60 0.051 0.55 0.00
10-Year Event Chainsaw Routing Results 0 Inflow
f Outflow
20 ' u
aMMINNUMMMINKHM
16 MMEM @ -
YI
t 14 '
Q12
rn 10 t
L 8
O 6
4 `
D
fD y
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00
i Time,T(min)
Williston_Deten_Pond_Arev-4.xls\Chainsaw Routing 10-Year

Kimley-Horn 5/l/00
and Associates, Inc. Sheet No.1 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
50-Year event Chainsaw Routing Max. Elev. = 39.25 Max. Disc. = 16.18 cfs
11/2" Principle Emergency
Time Inflow Storage Stage Elev Outflow Pipe Outflow Weir
(min) (cfs) (cu-ft) (ft) (ft) (cfs) (cfs) (cfs) (cfs)
0.00 0.00 24,063 3.50 37.25 0.00 0,000 0.00 0.00
2.68 0.41 24,063 3.48 37.23 0.00 0.000 0.00 0.00
5.36 1.62 24,129 3.49 37.24 0.00 0.000 0.00 0.00
8.04 3.54 24,390 3.51 37.26 0.00 0.000 0.00 0.00
10.72 6.02 24,959 3.56 37.31 0.00 0.001 0.00 0.00
13.41 8.90 25,928 3.65 37.40 0.02 0.018 0.00 0.00
16.09 11.94 27,356 3.78 37.53 0.03 0.027 0.00 0.00
18.77 14.95 29,273 3.94 37.69 0.04 0.037 0.00 0.00
21.45 17.69 31,673 4.15 37.90 0.05 0.045 0.00 0.00
24.13 19.97 34,511 4.38 38.13 1.95 0.053 1.90 0.00
26.81 21.62 37,410 4.61 38.36 7.54 0.061 7.54 0.00
29.49 22.52 39,675 4.79 38.54 7.70 0.065 7.70 0.00
32.17 22.60 42,059 4.97 38.72 7.86 0.070 7.86 0.00
34.85 21.87 44,430 5.15 38.90 8.02 0.074 8.02 0.00
37.54 20.36 46,658 5.31 39.06 9.05 0.078 8.16 0.89
40.22 18.32 48,479 5.44 39.19 13.40 0.081 8.27 5.14
42.90 16.38 49,270 5.50 39.25 15.94 0.082 8.31 7.62
45.58 14.64 49,341 5.50 39.25 16.18 0.082 8.32 7.86
48.26 13.09 49,094 5.49 39.24 15.35 0.082 8.30 7.04
50.94 11.70 48,731 5.46 39.21 14.18 0.081 8.28 5.90
53.62 10.46 48,334 5.43 39.18 12.98 0.081 8.26 4.72
56.30 9.35 47,929 5.40 39.15 11.85 0.080 8.23 3.62
58.98 8.36 47,528 5.37 39.12 10.84 0.080 8.21 2.63
61.67 7.48 47,130 5.34 39.09 9.94 0.079 8.18 1.76
64.35 6.68 46,733 5.32 39.07 9.18 0.078 8.16 1.02
67.03 5.98 46,333 5.29 39.04 8.55 0.078 8.14 0.42
69.71 5.34 45,918 5.26 39.01 8.14 0.077 8.11 0.03
72.39 4.78 45,468 5.22 38.97 8.08 0.076 8.08 0.00
75.07 4.27 44,936 5.18 38.93 8.05 0.075 8.05 0.00
77.75 3.82 44,328 5.14 38.89 8.01 0.074 8.01 0.00
80.43 3.41 43,654 5.09 38.84 7.97 0.073 7.97 0.00
83.11 3.05 42,921 5.03 38.78 7.92 0.072 7.92 0.00
Williston_Deten_Pond_Arev 4.xls\Chainsaw Routing 50-Year 1

Kimley-Horn 5nt00
and Associates, Inc. Sheet No.2 of 2
Job Wllislon Middle School Subject Detention Pond Design Job No. 01804700:3
Designed by AJG Date 3/17100 Checked by Date
50-Year event Chainsaw Routing Max. Elev. = 39.25 Max. Disc. = 16.18 cfs
11/2" Principle Emergency
Time Inflow Storage Stage Elev Outflow Pipe Outflow Weir
(min) (cfs) (cu-ft) (ft) (ft) (cfs) (cfs) (cfs) (cfs)
85.80 2.73 42,138 4.98 38.73 7.87 0.070 7.87 0.00
88.48 2.44 41,311 4.91 38.66 7.81 0.069 7.81 0.00
91.16 2.18 40,446 4.85 38.60 7.75 0.067 7.75 0.00
93.84 1.95 39,550 4.78 38.53 7.69 0.065 7.69 0.00
96.52 1.74 38,626 4.71 38.46 7.63 0.063 7.63 0.00
99.20 1.56 37,679 4.63 38.38 7.56 0.061 7.56 0.00
101.88 1.39 36,713 4.56 38.31 6.87 0.059 6.81 0.00
104.56 1.24 35,833 4.49 38.24 4.68 0.057 4.62 0.00
107.24 1.11 35,281 4.44 38.19 3.45 0.055 3.39 0.00
109.93 0.99 34,905 4.41 38.16 2.68 0.054 2.63 0.00
112.61 0.89 34.634 4.39 38.14 2.17 0.054 2.12 0.00
115.29 0.80 34,428 4.37 38.12 1.80 0.053 1.75 0.00
117.97 0.71 34,266 4.36 38.11 1.53 0.053 1.48 0.00
50-Year Event Chainsaw Routing Results t Inflow
--a-
Outflow
25
20
LU
Q 15 NMI
0 10 SWIN
m
M q1q WE MR
0 7 +i
0 20 40 60 80 100 120 1.40
1 Time,T(min)
Williston_Deten_Pond_Arev4.xls\Chainsaw Routing 50-Year

Kimley-Horn 5/1/00
and Associates, Inc. Sheet No.1 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
50-Year event Chainsaw Routing Max. Elev. = 39.44 Max. Disc. = 18.74 cfs
with primary structure blocked 1112" Principle Emergency
Time Inflow Storage Stage Elev Outflow Pipe Outflow Weir
(min) (cfs) (cu-ft) A (ft) (cfs) (cfs) (cfs) (cfs)
0.00 0.00 24,063 3.50 37.25 0.00 0.000 0.00 0.00
2.68 0.41 24,063 3.48 37.23 0.00 0.000 0.00 0.00
5.36 1.62 24,129 3.49 37.24 0.00 0.000 0.00 0.00
8.04 3.54 24,390 3.51 37.26 0.00 0.000 0.00 0.00
10.72 6.02 24,959 3.56 37.31 0.00 0.000 0.00 0.00
13.41 8.90 25,928 3.65 37.40 0.00 0.000 0.00 0.00
16.09 11.94 27,359 3.78 37.53 0.00 0.000 0.00 0.00
18.77 14.95 29,281 3.95 37.70 0.00 0.000 0.00 0.00
21.45 17.69 31,686 4.15 37.90 0.00 0.000 0.00 0.00
24.13 19.97 34,532 4.38 38.13 0.00 0.000 0.00 0.00
26.81 21.62 37,744 4.64 38.39 0.00 0.000 0.00 0.00
29.49 22.52 41,222 4.91 . 38.66 0.00 0.000 0.00 0.00
32.17 22.60 44,845 5.18 38.93 0.00 0.000 0.00 0.00
34.85 21.87 48,481 5.44 39.19 5.15 0.000 0.00 5.15
37.54 20.36 51,171 5.63 39.38 14.84 0.000 0.00 14.84
40.22 18.32 52,060 5.69 39.44 18.74 0.000 0.00 18.74
42.90 16.38 51,994 5.69 39.44 18.43 0.000 0.00 18.43
45.58 14.64 51,663 5.67 39.42 16.96 0.000 0.00 16.96
48.26 13.09 51,291 5.64 39.39 15.34 0.000 0.00 15.34
50.94 11.70 50,929 5.62 39.37 13.83 0.000 0.00 13.83
53.62 10.46 50,587 5.59 39.34 12.45 0.000 0.00 12.45
56.30 9.35 50,268 5.57 39.32 11.21 0.000 0.00 11.21
58.98 8.36 49,970 5.55 39.30 10.09 0.000 0.00 10.09
61.67 7.48 49,692 5.53 39.28 9.08 0.000 0.00 9.08
64.35 6.68 49,434 5.51 39.26 8.18 0.000 0.00 8.18
67.03 5.98 49,193 5.49 39.24 7.37 0.000 0.00 7.37
69.71 5.34 48,969 5.48 39.23 6.64 0.000 0.00 6.64
72.39 4.78 48,760 5.46 39.21 5.98 0.000 0.00 , 5.98
75.07 4.27 48,566 5.45 39.20 5.40 0.000 0.00 5.40
77.75 3.82 48,385 5.43 39.18 4.87 0.000 0.00 4.87
80.43 13.41 48,216 5.42 39.17 4.39 0.000 0.00 4.39
83.11 3.05 48,059 5.41 39.16 3.96 0.000 0.00 : 3.96
I
Williston_Deten_Pond_Arev-4.xls\50-Year CR w primary blocked

Kimley-Horn 511/00
and Associates, Inc. Sheet No.2 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3/17/00 Checked by Date
50-Year event Chainsaw Routing Max. Elev. = 39.44 Max. Disc. = 18.74 cfs
with primary structure blocked 1112" Principle: Emergency
Time Inflow Storage Stage Elev Outflow Pipe Outflow Weir
(min) (cfs) (cu-ft) (ft) (ft) (cfs) (cfs) (cfs) (cfs)
85.80 2.73 47,913 5.40 39.15 3.57 0.000 0.00 3.57
88.48 2.44 47,776 5.39 39.14 3.23 0.000 0.00 3.23
91.16 2.18 47,649 5.38 39.13 2.92 0.000 0.00 2.92
93.84 1.95 47,531 5.37 39.12 2.63 0.000 0.00 2.63
96.52 1.74 47,420 5.37 39.12 2.38 0.000 0.00 2.38
99.20 1.56 47,318 5.36 39.11 2.15 0.000 0.00 2.15
101.88 1.39 47,222 5.35 39.10 1.95 0.000 0.00 1.95
104.56 1.24 47,133 5.34 39.09 1.76 0.000 0.00 1.76
107.24 1.11 47,049 5.34 39.09 1.60 0.000 0.00 1.60
109.93 0.99 46,972 5.33 39.08 1.44 0.000 0.00 1.44
112.61 0.89 46,899 5.33 39.08 1.31 0.000 0.00 1.31
115.29 0.80 46,832 5.32 39.07 1.19 0.000 0.00 1.19
117.97 0.71 46,769 5.32 39.07 1.08 0.000 0.00 1.08
50-Year Event Chainsaw Routing Results ♦Inflow
f Outflow
25
'� 04M
1..Y20 5 a
p we +c
15 s.
Or
� f
0 10 1 Inca= Mal
5 NMI
0 '
0 20 40 60 80 100 120 140
Time,T(min)
Williston_Deten_Pond_Arev-4.xls%50-Year CR w primary blocked

Kimley-Horn 5f1100
and Associates,Inc. Sheet No.1 of 2
Job Williston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date 3117100 Checked by Date
2-5 Day Drawdown Analysis for first I"rainfall storage 1'runoff volume= 7,849 cu-ft
Elev Time Stage Storage Outflow
(hr) (days) (ft) (cu-ft) (cfm)
37.92 0 0.00 4.17 31,912 2.758
37.86 4 0.17 4.11 31,250 2.629 2-5 Day Drawdown Results
37.81 8 0.33 4.06 30,619 2.499
37.76 12 0.50 4.01 30,019 2.367 38.0
37.71 16 0.67 3.96 29,451 2.235
37.66 20 0.83 3.91 28,915 2.101
37.62 24 1.00 3.87 28,411 1.966 Sze
37.58 28 1.17 3.83 27,939 1.830
37.54 32 1.33 3.79 27,500 1.692 37.8
37.50 36 1.50 3.75 27,094 1.554
37.47 40 1.67 3.72 26,721 1.414 37.7' -
37.44 44 1.83 3.69 26,382 1.272 - -
37.41 48 2.00 3.66 26,076 1.130
37.39 52 2.17 3.64 25,805 0.985 37.6 -
37.37 56 2.33 3.62 25,569 0.838 Y
37.35 60 2.50 3.60 25,368 0.688 w 37.5 - -- fOutnow
37.34 64 2.67 3.59 25,202 0.534 w
37.32 68 2.83 3.57 25,074 0.373 a 374
37.32 72 3.00 3.57 24,985 0,192
37.31 76 3.17 3.56 24,939 #NUMI -
37.3
t
37.2 -
37.1 -
37.0
0.00 1.00 2.00 3.00 4.00 5.00
Time,T(days)
i
r
Williston Deten_Pond Arev-4.xlst2-5 Day Drawdown

Kimley-Horn 511100
and Associates, Inc. Sheet No.2 of 2
Job Wlliston Middle School Subject Detention Pond Design Job No. 018047003
Designed by AJG Date W17/00 Checked by Date
2-5 Day Drawdown Analysis for first 1"rainfall storage 1"runoff volume= 7,849 cuff
Elev Time Stage Storage Outflow
(hr) (days) (ft) (cu-ft) (cfm)
Elev Time Stage Drawdown 2-5 Day Drawdown Results
(hr) (days) (ft) of 1"vol.
37.92 0.00 0.00 4.17 7,849 10,000
37.86 4 0.17 4.11 7,187
37.81 8 0.33 4.06 6,556 9.000
37.77 12 0.50 4.01 5,957
37.72 16 0.67 3.96 5,388 8,000
37.68 20 0.83 3.91 4,852
37.63 24 1.00 3.87 4,348
37.60 28 1.17 3.83 3,876 7,000
37.56 32 1.33 3.79 3,437
37.53 36 1.50 3.75 3,031 5,000
37.50 40 1.67 3.72 2,658 - -
37.47 44 1.83 3.69 2,319 -
37.45 48 2.00 3.66 2.013 E 5.000 torawdown
37.42 52 2.17 3.64 1.742 2
37.41 56 2.33 3.62 1,506 ' 4,000
37.39 60 2.50 3.60 1,305
37.38 64 2.67 3.59 1,140 3.000
37.37 68 2.83 3.57 1,011
37.37 72 3.00 3.57 922
33.81 76 3.17 3.56 876 2,000
1,000
0
0.00 1.00 2.00 3.00 4.00 5.00
Time,T(days)
i
Wlliston_Deten_POnd_Arev 4.xis12-5 Day Drawdown

C0� ndAs-Hom
a
0 and Associates,Inc. n Sheet No.—or
Job (� I N„ �n.1 Subject 7___, U .J-t t t !'i l 4--'Tl Job No. ` -L104 v T 2s_
Designedby /-' Date /=%�� Checkedby Date
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May 6, 1999
RECEIVED
MAY 14 1999
New Hanover County Schools
1802 South 15th Street SHARPE Architecture
Wilmington, No h Carolina 28401
Attention: Mr. Carmen V. Gintoli, R.A.
Reference: Soil Borings
Proposed Stormwater Ponds
Williston Middle School
Wilmington, North Carolina
Job No. 1061-99-162
Dear Mr. Gintoli:
S&ME has recently conducted a field study of the near-surface soils at the
proposed Stormwater Ponds sites at the Williston Middle School campus located in Wilmington,
North Carolina. Our field activities included the following:
1. Advanced four soil test borings (Borings SB-1 through SB-4) to a depth of
10 feet below the existing ground surface using a rotary drill rig. Soii
samples were obtained by the ASTM D-1586 standard penetration test
method to determine the consistency of the subsurface soils.
2. Advanced three hand-augered borings to depths ranging from
approximately 25 to 36 inches below the existing ground surface.
f an
Representative samples of the excavated soils were issueallll ,ned i using a
ied
the hue, value, and chroma of each stratum
Munseil chart.
3. Excavated one test pit to a depth of about 5 feet below the existing ground
surface and observed the in-place soil and water conditions.
The approximate locations of the soil test borings, the hand-augered borings, and
the test pit are shown in Figure 1.
5&ME. Inc. 19101 799.99d5
6409 Amsterdam Way, Building 8.7 I910 1 799-9958 fax
Wilmington. North Carolina 28405 w .smeinc.com

New Hanover County Schools
May 6, 1999
Page Two
Subsurface Soil Conditions
The subsurface corditions encountered at the sampling locations generally
consisted of intermittent layers of very loose to medium dense silty sands, slight, silty sands,
and clean sands which extended to a depth of about 6 feet below the existing ground surface. At
Borings SB-I, SB-2, and SB-3, very loose to loose clean sands extended from a depth of
approximately 6 feet to the maximum completed boring depth of 10 feet. At Boring SB-3,
though, a layer of very soft to soft organics and peat was noted from a depth of approximately 6
feet to the completed boring depth of 10 feet.
Thin layers of weakly cemented sands (known locally as "hardpan") were noted to
occur at various depths within the upper 6 feet of the in-place soils. "Hardpan" soils are
relatively impermeable and restrict the gravity flow of surface water through the subsurface soils.
More detailed descriptions of the site subsurface conditions are presented in Table
1 and in the attached Test Boring Records. Two photographs showing the test pit excavation
work are attached as Table 2.
Groundwater Conditions
The depth to water was noted during the drilling of the soil test borings at about 4
feet below the existing ground surface. The use of drilling mud to advance the soil borings made
it difficult to determine the water level upon completion of the drilling work. The boreholes
were backfilled upon completion of the drilling work due to safety concerns.
The depth to water in the hand-augered borings ranged from 10 to 22 inches
below the existing ground surface. At the test pit location, water was observed to initially seep
into the excavation at a depth of about 4'/2 feet. After a period of 15 minutes, the water level in
the test pit had risen to within 3 feet of the ground surface. The soils and cypress tree roots
which had been removed during the excavation work were then replaced in the excavation and
the disturbed area regraded. "
Comparison of the coloration of the soils encountered in the hand auger borings to
a Munseil soil color chart shows chroma values of 1 for all the distinct layers of soil. Values of 2
or less are associated with chronic submerged condition.

New Hanover County Schools
May 6, 1999
Page Three
Comments and Conclusions
Based on our past experience with similar soils, we estimate the following
hydraulic conductivity values for the in-place soils: - -
Hydraulic Conductivity
Soil Description (Centimeter/second)
Clean or Slightly Silty SAND 1 x 10-2 to 1 x 10-3
Silty SAND 1 x 10" to 1 x 10'5
Weakly Cemented SAND (Hardpan) 1 x 10-6 to I x 10-8
The presence of relatively impermeable hardpan layers will cause a shallow
perched water condition to occur after periods of heavy or extended rainfall. Soil coloration
suggests that this perched water level occurs at or near the ground surface level on a seasonal
basis. We feel that the shallow depth to water at the hand-augered boring locations and at the
test pit excavation is perched water which cannot readily seep downward through the layers of
hardpan. This is confirmed by the U.S. Department of Agriculture publication, "Soil Survey of
New Hanover County, North Carolina" which indicates that the near-surface soils at the subject
site consist of the Leon series soils, which have a seasonal high water table occurring within one
foot of the ground surface. This seasonal high water is due to a perched water condition that
most frequently occurs from June through February.
On a less technical level, the subject site is in an area of Wilmington known as
"Dry Pond". We understand that a series of ponds were located in this area which only contained
water during the wet portions of the year. Since these ponds were empty of water during dry
periods, they became known as dry ponds. This also indicates that noticeable variations in
perched water levels will occur throughout the year.

New Hanover County Schools
May 6, 1999
Page Four
Closing Remarks
S&ME appreciates having the opportunity to be of service to you during this phase of
the project. If you have any questions or comments after reviewing this report, or if we can be of-
additional service to you, please do not hesitate to contact us at your convenience.
Very truly yours,
S&ME,INN�C.
Steven D. Kelly, P.EE
N. C. Registration No. 17638
Michael W. Behen, P.E.
N.C. Registration No. 8384
SDK:MWB/jns
Attachments
Copy: Kimley-Hom and Associates, Mr. Chris Ford

TABLE I
Soil Descriptions
Proposed Stormwater Retention Ponds
Williston Middle School
Wilmington, North Carolina
Job No. 1061-99-162
Location Depth Hue Value/Chroma Soil Description
1 0-18" 2.5Y 2.5/1 Black Fine to Medium SAND—Trace of Silt
18"-24" 2.5Y 3/1 Very Dark Gray Fine to Medium SAND —
Trace of Silt
24"-25" 2.5Y 2.5/1 Black Fine to Medium SAND —Trace of Silt
Groundwater was encountered at a depth of 10" below the existing ground surface.
2 0-23" 2.5Y 4/1 Dark Gray Fine to Medium SAND—Trace of
Silt
23"-25" 2.5Y 2.5/1. Black Fine to Medium SAND —Trace of Silt
Groundwater was encountered at a depth of 18" below the existing ground surface.
3 0-15" 2.5Y 3/1 Very Dark Gray Fine to Medium SAND —
Trace of Silt
15"-35" 2.5Y 511 Gray Fine to Medium SAND —Trace of Silt
Groundwater was encountered at a depth of 22" below the existing ground surface.

TABLE 2
Photographs
Test Pit Excavation Work (5-4-99)
Proposed Stotmwater Retention Ponds
Williston Middle School
Wilmington, North Carolina
Job No. 1061-99-162
47
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77
news . .
• .tiwC K.�Y y
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HwY SB-1 IN l-;
P'4«• 3
IkYlln�l
Note: Site plan drawing provided to S&NE by New Hanover County Schools personnel.
LEGEND
• APPROXIMATE LOCATION OF SOIL. TEST BORING
SB-1
APPROXIMATE LOCATION OF NAND-AUGERED BORING
I
P-1 APPROXIMATE LOCATION OF TEST PIT
PROJECT
* CAQNmcS(? �1LE : Not to Scale
PROPOSED STORMWATER P,,NDS
WII.LLSTON MIDDLE SCHO, I. � �-

GENERALIZED SUBSURFACE PROFILE
DEPTH
(FT.)
SB-2
SB-7 SB-4
22 a
6 4
5 iS B s
7
e e.
4
4 2 9
NOTE See Legend and attached Test Boring Records for soil descriptionu.
The subsurface conditions may vary intermediate of the soil test
boring locations.
PROJECT
PROPOSED STORMWATER PONDS I L E Not to Scale
r
WiLLTSTf)N MUMI r vrf" — I �&

PROJECT: PROPOSED STORMWATER POND TEST BORING RECORD SB-`
MTLMDJGTON. N.G
PROJECT NO.• !Oet-on-199 ELEVATION: 0 NOTES:
LOGGED BY: PB BORING DEPTH: 10 FEET
DATE DRIILED: 5-3-99 WATER LEVEL: 4'
DRILLING METHOD: WASN BORING DRII.L RIG: CW45
e w W Standard Penetration Test Data
Sall Description > W (Blows/It)
o _
10 30 50 70:
Grass and Loamy Soil
Medium Dense Gray Fine to Medium SAND
(SP)_ I I 1 I I I I
FMedlenseBlack Fine to Medium SAND
5 (SP-SM)
Loose Brown and Dark
edium SAND (SP)
0 -io
Boring completed at 10'.
I
IS —�
20
25 -n
30
L35 -
Page:ldl!
$&ME
Enworonental Sermes
Enaneerma • re5vna

PROJE=: PROPOSED STORNNATER POND TEST BORING RECORD S8
NILNTrlGTON. N.G
PROJECT NO.: 8S-l09 ELEVATION: 0 N07M .
LOGGED BY: PB BORING DEPTH: 10 FEET'
DATE DRILLED: 5-3-99 WATER LEVEL• 4�
DRILLING NETHOIZ MASH BORING DRILL RIG: CPE45
X '2 w m > Standard Penetration Test Data
Sall Description o .- W °y+' (slaws/it)
J f f W 10 30 50 /
Grass and Loamy Soil
Loose Gray Fine to Medium SAND (SP)
Loose Dark Brown Fine to Medium SAND -
5 Some Silt - Trace of Organics
Loose Brown Fine to Medium SAND (SP)
10 -10
Boring completed at 10'.
15 -�
10 -p
25 -25
30 - -30 ..
-35
35
Page:lall
# $&ME
Enae+eerna � fesnna

PROJECT: PROPOSED STORMMATER PONDWFEEI
ORING RECORD SB-
WILM04GTON. KG
PROJECT NO.: 1091-09-199 ELEVATION: 0S:
LOGGE13 By. PB BORING DEPTH:
DATE ORIlLED: S-3-99 WATER LEVEL' 4'
DRILLING METHOD: MASH BORING GRILL RIG: CME4
x tantlartl Penetration Test 0ata
sal Description (Blows/ft)
C3 ¢ 10 30 50 7(
Grass and Loamy SollLoose Dark Brown Fine to Medium SANG -
liit (SM) I_
Loose Brown Fine to Medium SANG -
5 Trace of Silt (SP-SM)
Soft to Very Soft Oark Brown PEAT and
ORGANICS (PT)
to -10
Boring completed at 10'.
S -15
20 -20
25 -25
30 -so
35 -35
Pape:lall
$&ME
C..pger.nr + Teter�n

PROJECT. PROPOSED STORNMATER POND TEST BORING RECORD SB
MD.NDVGTON. KG
PROJECT NO.: 061-99-198 t1c^iA TICN: 0 NOTES.* _.
LOGGED BY: PH BORING DEPTH: to FEET
DAZE 5-3-99 WATER LEVEL.• 4'
DRILLING NETHOr NASN BORING DRILL RIG: f:1E45
Standard Penetration Test Data
Soil Description w (Blows/It)
0
f0 30 50 701
w
Grass and Loamy Soil
Very Loose Black Fine to Medium SAND - _ t\
Some Slit .(SM)Loose
---
Loose Brown Fine to Medium SAND -
5 Trace of Slit (SP-SM)
Very Loose to Loose Brown and Tan Fine
to Medium SAND (SP)
I -q
Boring completed at 10'.
15 -�
20 -10
FAII
15 -IS
30 -30
-35
35
Pape:loll
* $&ME

02/24/2000 09:40 FACILITY PLANNING 97920277 N0.391 902
n`Lni4'4252g2j \
S&ME February 18, 2000
`o �0 I
O�RFP p'%N' A
co
\9V
9
New Hanover County Schools F�ZI COOL 68L
1802 South 15'Street
Wilmington,North Carolina 28401
'Attention:' tvfr. vr' Carmen uui�u V, Gintoli
�
Reference: Hand-Augered Borings
Proposed Storm Water Pond Site
Gregory Elementary School-
Wilmington,North Carolina
Job Number 1063-00-068
Dear Mr. Gintoli:
S&ME personnel recently advanced four hand-augered borings at a proposed storm water
retention pond site (Figure 1) at the existing Gregory Elementary School campus in Wilmington, North
Carolina. These borings were advanced to depths ranging from approximately 2%z to 3%: feet below the
existing ground surface. The recovered soil samples were visually classified by our representative using a
Munsell chart.
Upon completion of the soil sampling work, our personnel measured the depth to water.
On February 10,2000,the depth to water ranged from 21 to 35 inches below the existing ground surface.
Details concerning the site subsurface conditions are presented in Table I.
If you have any questions after reviewing this letter, or if we can be of additional assistance,
please do not hesitate to contact us at your convenience.
very truly yours,
S&ME,INC.
&�' t
Steven D.Kelly,P.E.
Branch Manager .
/A�V$,411( W.
A4ichael W.Behen,P.E.
Senior Geotechnical Engineer
SDK:MWB/ins
Attachments
SWE. Inc. )910)799.9945
6409 Amsrerdom Way, Building 61 )910)799-9958 lox
Wllmingmn,Noah Ccralino 28405 %V w.smeinc.com
(�-LOCATION,9102544238 r7,(p/ RX TIME 02/24 '00 09:36

02/242000 09:40 FACILITY PLANNING 4 97920277 N0.391 D03
Hand Auger Borings(l)
Proposed Storm Water Pond Site
Gregory Elementary School
Wilmington, North Carolina
Job Number 1063-00-068
Location Depth Hue Chroma Soil Description
1 0-14" 10 YR 3/3 Dark Browri Fine to Medium SAN') - Trace of Silt
14"-30" 10 YR 2/1 Black Fine to Medium SAND - Some Silt
Groundwater was encountered at a depth"of 21"below the existurg t6und s ace.
2 0-12" 10 YR 212 Very Dark Brown Fine to Medium SAND -Trace of Silt
12"-28" 2.5 Y 3/1 Very Dark Gray Fine to Medium SAND -Trace of Silt
28"-42" 2.5 Y 4/1 Dark Gray Fine to Medium SAND- Trace of Silt
Groundwater was encountered at a depth of 35" below the existing ground surface.
3 0-8.5" 10 YR 2/2 Very bark Brown Fine to Medium SAND -Trace of Silt
10 YR 4/3 Brown Fine to Medium SAND-Trace of Silt
14"-27" 10 YR 5/2 Grayish-Brown Fine to Medium SAND-Trace of Silt
27"-34" 10 YR 2/1 Black Fine to Medium SAND - Some Stilt
Groundwater was encountered at a depth of 33"below the existing ground surface.
4 0-16.5" 10 YR 2/1 Black Fine to Medium SAND -Trace of Silt with Organics
16.5"-22" 10 YR 3/2_ Very Dark Grayish Brown Fine to Medium SAND,-a
'Little Silt
22"-35" 10 YR 411 Dark Gray Fine to Medium SAND -Trace of Silt
Groundwater was encountered at a depth of 31" below the existing ground surface.
(')All borings were advanced by S&ME personnel on February 10, 2000, using a hand auger.
LCCATION:9102544238 RX TIME 02/24 '00 09:36

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Note: Site plan drawing provideli to S&ME by New Hanover County Schools peraonpel.
LEGEND
! *1 Approximate Location of Hand-Augered Boring 2
c
PROJECT f ffG
LE : .Not to stele
GREGORY ELEMENTARY SCHOOL1063-00-068PROPOSED STORM WATER POND (SITE i NO.NOW
WILMINGTON. NORTH CAROLINANO. 1 a

Copyright 1997 AIA MASTERSPEC RECEIVED 5/94
MAY 0 9 2000
SECTION 02630—STORM DRAINAGE
PART I-GENERAL
1.1 RELATED DOCUMENTS
A. Drawings and general provisions of the Contract, including General and Supplementary Condi-
tions and Division 1 Specification Sections,apply to this Section.
1.2 SUMMARY
A. This Section includes furnishing all materials, plant, labor and equipment necessary for the com-
plete installation of storm drainage mains, fittings, manholes, catch basins, inlets,junction boxes,
channel linings,structures,headwalls and appurtenances outside the building.
B. Related Sections include the following:
1. Section 02230—Site Clearing
2. Section 02300—Earthwork
1.3 DEFINITIONS
A. RCP: Reinforced-Concrete Pipe.
B. PVC: Polyvinyl chloride plastic.
C. CPP: Corrugated Polyethylene Pipe.
D. HDPE:High density polyethylene.
E. PE: Polyethylene plastic.
F. CMP: Corrugated Metal Pipe.
1.4 SYSTEM PERFORMANCE REQUIREMENTS
A. Gravity-Flow,Nonpressure-Piping Pressure Ratings: At least equal to system test pressure.
1.5 SUBMITTALS
A. General:All submittals shall be submitted to the Engineer in accordance with the conditions of the
contract and Division 1 Specification Sections.
B. Product Data: For the following:
1. Precast Concrete Structures.
2. Manhole covers and inserts.
3. Storm Drain Pipe
4. Storm Drain Pipe Fittings
5. Manhole Brick or Block
6. Stormwater disposal systems
C. Shop Drawings: Include plans,elevations,details,and attachments for the following:
1. Cast-in-place concrete manholes and other structures, including frames and covers.
2. Transition couplings
D. Concrete and Asphalt Mix Designs: Shall be submitted to the Engineer for approval if requested
by the Engineer for each class of cast-in-place concrete if requested.
E. Coordination Drawings: For piping and specialties including relation to other services in same
area. Show piping and specialty sizes, locations,and elevations.
F. Record Drawings:At Project closeout of installed storm drainage piping according to Division 1
Section "Closeout Procedures."
G. Test Reports:As specified in "Field Quality Control'Article in Part 3.
1.6 QUALITY ASSURANCE
A. Product Options: Drawings indicate size,profiles,and dimensional requirements of storm drainage
piping specialties and are based on specific types and models indicated. Other manufacturers'
products with equal performance characteristics may be considered provided deviations in dimen-
sions, operation, and other characteristics do not change the design concept or intended perform-
ance as judged by the Engineer and governing authorities. The Contractor shall bear the burden of
proof of product equality. Refer to Division 1 Section "Substitutions".
B. Comply with requirements of the City of Wilmington including tapping of storm drain manholes.
C. Comply with standards of authorities having jurisdiction for sanitary sewer systems including the
North Carolina Department of Environment and Natural Resources,Division of Water Quality and
The City of Wilmington. Include materials,installation and testing.
D. Provide listing/approval stamp, label,or other marking on piping and specialties made to specified
standards.
STORM DRAINAGE 02530-1
Williston Middle School—Phase 11 Renovations

Copyright 1997 AIA MASTERSPEC 5/94
E. Material Testing:
I. Pipe: Pipe shall be tested in accordance with AWWA, ASTM and ANSI Standard re-
quirements for each type.
2. Fittings: Pipe fittings shall be tested in accordance with AWWA, ASTM and ANSI Stan-
dard requirements for each type.
3. Gaskets: Gaskets shall be tested in accordance with AWWA, ASTM and ANSI Standard
requirements for each type.
4. Other materials: Testing of any materials shall be provided as requested by the Engineer
or governing authorities, when the acceptability of the installation or materials is ques-
tioned.
F. Soil Testing:
1. The owner shall retain the services of a testing laboratory to perform field density tests
when and as deemed necessary by the owner or Engineer. These tests shall be performed
at no cost to the contractor with the following exceptions:
- a) Tests are required by the governing authorities, including the City of Wilming-
ton and the North Carolina Department of Transportation, to verify proper in-
stallation by the contractor.
b) Tests identify defective work or materials or indicate improper soil placement
and compaction.
2. The Contractor shall be responsible for the cost of testing borrow material to include, but
not be limited to,grain size analysis and standard density tests.
G. Sedimentation and Erosion Control: Provide sedimentation and erosion control in compliance with
the N.C. Sedimentation Pollution Control Act of 1973 and the North Carolina Department of En-
vironment and Natural Resources,Division of Land Quality guidelines. Erosion and sedimentation
control methods and devices shall be in accordance with the N.C. Sedimentation and Control
Manual and the approved plans. The contractor shall employ construction methods that will mini-
mize siltation and erosion.Such methods shall provide adequate control of siltation and erosion by
limiting unnecessary excavation, disturbing or uprooting trees and vegetation, dumping if soil or
debris,or pumping silt-laden water into streams. Cleanup, grading, seeding, and planting or resto-
ration of all work areas shall begin immediately. Exposed areas shall not remain unprotected for
more that seven days.
1.7 DELIVERY, STORAGE,AND HANDLING
A. Deliver plastic piping with factory-applied end-caps. Maintain end-caps through shipping, stor-
age, and handling to prevent pipe-end damage and to prevent entrance of dirt, debris, and mois-
ture.
B. Protect stored piping from moisture and dirt. Elevate above grade. Do not exceed structural ca-
pacity of floor when storing inside.
C. Protect flanges,fittings,and specialties from moisture and dirt.
D. Store plastic piping protected from direct sunlight. Support to prevent sagging and bending.
E. Handle precast concrete manholes and other structures according to manufacturer's written rigging
instructions.
1.8 PROJECT CONDITIONS
A. Verify existing utility locations. Existing utility locations are approximate based on information
by others and are provided for information only. Locations indicated on plans are not intended as
representations or warranties of accuracy. Contact utility-locating service for area where Project is
located prior to construction.
B. Verify that storm drainage piping may be installed to comply with original design and referenced
standards.
C. Locate existing structures and piping to be closed and abandoned or removed.
D. Subsurface Information:
1. Subsurface investigations and soil analyses have been completed at selected locations on
the site. Test boring records,analyses, reports, and related recommendations and conclu-
sions are included as Addendum A. Plans indicate specific soil boring locations.
2. Data in reports are provided for information only and are not intended as representations
or warranties of accuracy or continuity of conditions between soil borings. Owner as-
sumes no responsibility for interpretations or conclusions drawn from this information.
STORM DRAINAGE 02530-2
Williston Middle School—Phase I1 Renovations

Copyright 1997 AIA MASTERSPEC 5/94
1.9 SEQUENCING AND SCHEDULING
A. Coordinate connection to City storm drainage with the City of Wilmington.
B. Coordinate piping materials, sizes and entry locations with building storm drainage piping where
applicable.
C. Coordinate with other utility work.
D. Existing Utilities: Do not interrupt utilities serving facilities occupied by Owner or others unless
permitted under the following conditions and then only after arranging to provide temporary utility
services according to requirements indicated:
1. Notify Engineer not less than seventy-two hours in advance of proposed utility interrup-
tions.
2. Do not proceed with utility interruptions without Engineer's written permission.
PART 2-PRODUCTS
2.1 STORM DRAINAGE PIPE
A. General
1. All materials shall meet the following minimum criteria. Where the governing authority's
specifications are more stringent, they shall govern. It shall be each manufacturer's re-
sponsibility to check the proposed installation and furnish material that will be fully ca-
pable of performing its intended function.
2. Where material and product specifications are shown on the drawings,they shall govern.
Where material and product specifications are not shown on the drawings, the require-
ments of this specification shall govern.
3. Pipe shall be of the type, size, class and diameter as specified hereinafter and denoted on
the plans. Pipe diameter specified shall be the minimum net inside diameter after the lin-
ing is placed. General design considerations shall comply with all applicable AWWA
Standards and to the following:
a) Trench width shall be 2'plus the outside diameter of the pipe.
b) Laying condition "C" (flat bottomed trench with tamped backfill) to withstand
all internal pressures and external loads.
c) Minimum depth of cover of 3' for pipelines eight (8) inches in diameter and
smaller and 3'-6" for pipelines ten (10) inches in diameter and larger, and
greater depths of cover where required by the plans
d) H-20 live load in accordance with AASHTO Specifications.
4. Applications of the following pipe materials are indicated in Part 3 "Piping Applications"
Article.
B. Reinforced-Concrete Pipe(RCP):ASTM C-76,Class III,Wall B for gasketed joints.
1. Pipe shall bear identification markings on each joint that will remain legible during nor-
mal handling,storage,and installation.
2. Pipe shall be furnished in eight (8) foot joints for sizes 12-inches through 24-inches ex-
cept where shorter joints are needed for tie-ins. The City of Wilmington prefers that ALL
sizes of RCP be furnished in the eight(8)foot lengths when the Contractor has the proper
equipment and sufficient working area. Permission may be granted for use of other length
joints by the Engineer on a case by case basis.
3. Gaskets: ASTM C 443,rubber.
C. Reinforced-Concrete Arched Pipe:ASTM C 506,Class IV,for banded joints.
1. Sealing bands:ASTM C 877,Type I.
D. Reinforced-Concrete Elliptical Pipe: ASTM C 507, Class IV, for banded joints and ASHTO M-
207.
1. Pattern: Type HE,horizontal.
2. Pattern: Type VE,vertical.
3. Sealing Bands:ASTM C 877,Type I.
E. Corrugated Metal Pipe: ASTM A 760 and AASHTO M-36, Type I made from ASTM A 929 zinc
coated.
1. Pipe shall be fully bituminous coated. Pipe sizes of 54-inches or less shall have the invert
paved with bituminous concrete. Pipe sizes larger than 54-inches shall be fully paved
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with bituminous concrete (smooth flow). All placement of bituminous concrete in Pipe
shall be in accordance with AASHTO M-190. When the invert of corrugated steel arch
pipe is required to be paved,the pavement shall extend across the entire invert.
2. All pipe shall be furnished in accordance with the gage and corrugation specified in the
Special Conditions and/or as specified on the plans.
3. Pipe shall be suitable for supporting an HS-20 live load, under the installations shown on
the plans.
4. Pipe shall be fitted with two lifting lugs on each joint of pipe.
5. Fittings: Fabricated to types indicated and according to same standards as pipe.
6. Connecting Bands: Standard couplings made for corrugated-steel pipe in accordance with
ASTM Specification A444 to form soil tight joints.
F. Corrugated Aluminum Pipe: ASTM B 745/13, Type 1,made from ASTM B 744B aluminum-alloy
sheet for banded joints.
1. All pipe shall be furnished in accordance with the gage and corrugation specified in the
Special Conditions and/or as specified on the plans.
2. Pipe shall be suitable for supporting an HS-20 live load, under the installations shown on
the plans.
3. Pipe shall be fitted with two lifting lugs on each joint of pipe.
4. Fittings: Fabricated to types indicated and according to same standards as pipe.
5. Connecting Bands: Standard couplings made for corrugated-steel pipe in accordance with
applicable ASTM Specification to form soil tight joints.
G. Corrugated PE Drainage Tubing and Fittings: ASSHTO M 252,Type S with smooth waterway for
coupling joints.Coupling joints shall be in accordance with ASTM 252,corrugated,matching tube
and fittings to form soil tight joints.
H. Corrugated Polyethylene Pipe(CPP)
1. Corrugated polyethylene pipe shall be manufactured from high density polyethylene
(HDPE)virgin compounds,and shall conform to the following standards:
a) AASHTO M-252 3"- 10"Diameter Pipe
b) AASHTO M-294 12"-36"Diameter Pipe
c) AASHTO MP6—95 42"- 48"Diameter Pipe
2. Fabrication: Corrugated polyethylene pipe of all types shall be fabricated with annular
corrugation conforming to AASHTO M-294.
3. A certificate of compliance shall be furnished to the engineer on record for each type of
plastic pipe furnished.
4. Designation of Type: The types of pipe will be indicated on the plans by the following
descriptions:
a) Pipe Description:CPP-(Corrugated Polyethylene Pipe)
(1) Type S- Pipe shall have a full circular cross-section,with an outer cor-
rugated pipe wall and a smooth inner liner.
(2) Type SP - Pipe shall have a full circular cross-section, with an outer
corrugated pipe wall and a smooth inner liner. Pipe shall include perfo-
rations.
(3) Type D - Pipe shall have a full circular cross-section, with a smooth
outer wall and a smooth inner wall.High Capacity(HC)trade name.
5. Pipe and Fittings
a) High Density Polyethylene Pipe and fittings: AASHTO M 252, Type S,
(Smooth Interior)ADS N-12 or approved equal.
(1) Pipe sizes:4 to 10 inches.
(2) Joints: Snap couplers
b) High Density Polyethylene Pipe and fittings: AASHTO M 294, Type S,
(Smooth Interior with integrated bell & spigot joints) ADS N-12 Ultra or ap-
proved equal.
(1) Pipe sizes: 12 to 36 inches.
(2) Joints: Integrated bell&spigot w/ASTM F477 rubber gasket on Spigot
end. Pipe and Bell must be of one homogeneously molded piece.
Welded or friction bells will not be accepted.
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c) High Density Polyethylene Pipe and fittings: AASHTO MP6-95, Type D,
Smooth exterior and smooth Interior.ADS N-12(HC)or approved equal.
(1) Pipe sizes:42 to 48 inches.
(2) Joints: Integrated bell and spigotjoints.
6. Coupling Bands
a) Except as otherwise required herein, repair coupling bands and other hardware
for corrugated polyethylene pipe shall demonstrate that they meet the soil tight-
ness requirements of AASHTO section 26.4.2.4, "Standard Specifications for
Highway Bridges".
b) Coupling bands shall lap equally on each of the pipes being connected to form a
tightly closed joint after installation.
c) The corrugations in the band shall index the corrugations in the pipe ends to en-
gage the first or second corrugation from the end of each pipe.
d) When infiltration or exfiltration is a concern, the coupling may be required to
have gaskets. The gasket material shall be closed-cell expanded rubber or neo-
prene.
I. Polyvinyl Chloride(PVC)Gravity Sewer Pipe and Fittings,NPS 15 and Smaller:
1. PVC pipe shall be type PSM rigid polyvinyl chloride plastic having a cell classification
of 12454-B, 12454-C, 12364-C or 13364-B made from virgin compounds as defined in
ASTM D1784 with integrally formed factory-fabricated bell for rubber type O-ring gas-
keted joints. Pipe shall conform to ASTM D 3034, SDR 35. Pipe surfaces shall be free
from nicks and scratches. The joining surfaces of pipe spigots and of integral-bell and
sleeve-reinforced bell sockets shall be free from gouges and other imperfections that
might cause leakage at joints. All fittings and accessories shall have bell and spigot con-
figurations identical to pipe.Elastomeric seal shall be in accordance with ASTM F 477.
2. Pipe shall bear identification markings that will remain legible during normal handling,
storage,and installation. Markings to include nominal size and OD base, PVC,dimension
ratio, ASTM designation and manufacturer's name or trademark and production-record
code.
3. Pipe laying length shall be 12.5' nominal except where random lengths are required for
special conditions or uses.
J. Polyvinyl Chloride(PVC)Gravity Sewer Pipe and Fittings,NPS 18 and Larger:
1. PVC pipe shall be type PSM rigid polyvinyl chloride plastic having a cell classification
of 12454-B, 12454-C, 12364-C or 13364-B made from virgin compounds as defined in
ASTM D1784 with integrally formed factory-fabricated bell for rubber type O-ring gas-
keted joints. Pipe shall conform to ASTM F 679, T-1. Pipe surfaces shall be free from
nicks and scratches. The joining surfaces of pipe spigots and of integral-bell and sleeve-
reinforced bell sockets shall be free from gouges and other imperfections that might
cause leakage at joints. All fittings and accessories shall have bell and spigot configura-
tions identical to pipe.Elastomeric seal shall be in accordance with ASTM F 477.
2. Pipe shall bear identification markings that will remain legible during normal handling,
storage,and installation. Markings to include nominal size and OD base, PVC,dimension
ratio, ASTM designation and manufacturer's name or trademark and production-record
code.
3. Pipe laying length shall be 12.5' nominal except where random lengths are required for
special conditions or uses.
2.2 SPECIAL PIPE COUPLINGS AND FITTINGS
A. Sleeve-Type Pipe Couplings: ASTM C 1173, rubber or elastomeric sleeve and band assembly fab-
ricated to mate with OD of pipes to be joined, for nonpressure joints.
1. Sleeve Material for Plastic Pipe:ASTM F 477,elastomeric seal.
2. Sleeve Material for Dissimilar Pipe: Compatible with pipe materials being joined.
3. Bands: Stainless steel,at least one at each pipe insert.
B. Bushing-Type Pipe Couplings: ASTM C 1173, rubber or elastomeric bushing fabricated to mate
with OD of smaller pipe and ID of adjoining larger pipe,for nonpressure joints.
1. Material for Plastic Pipe:ASTM F 477,elastomeric seal.
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2. Material for Dissimilar Pipe: Compatible with pipe materials being joined.
2.3 FLARED END SECTIONS:
A. General: Flared end sections(FES)shall be installed at locations shown on the plans or as directed
by the Engineer. FES's shall be manufactured of the same material as the pipe to which it is being
connected and shall be manufactured and installed with the same type of joint as the pipe.
B. Reinforced Concrete FES's: Reinforced concrete flared end sections shall be manufactured in ac-
cordance with plans that have been approved by the North Carolina Department of Transportation.
The concrete used in FES's shall attain a strength of 3500 psi when tested in accordance with
AASHTO 722. Where grates are to be installed on FES's, provisions for mounting the grate shall
be provided.
C. Corrugated Metal FES's: Corrugated metal FES's shall be manufactured in accordance with plans
provided by the manufacturer and approved by the Engineer. FES's on which the coatings has
been damaged or broken, either in the shop or in shipping, shall be repaired in accordance with
applicable specifications. All corrugated FES's shall be fully bituminous coated and shall have bi-
tuminous concrete paved inverts.
2.4 BRICK
A. Brick shall conform to AASHTO M-91-90, Grade MS, and shall be WHOLE solid brick of stan-
dard size, with straight and parallel edges and square corners. They shall be of compact texture,
full weight,entirely true,free from injurious cracks and flaws,tough,strong,and shall have a clear
ring when struck together.
2.5 CASTINGS
A. All castings for storm drain structures shall be Gray Iron castings manufactured in accordance
with ASTM A-48, latest revision and shall be fabricated in accordance with the City of Wilming-
ton Standard Details for each casting. Storm drain manholes shall have the words "STORM
DRAIN"or"STORM SEWER"cast in the lids.
2.6 FILTER FABRIC
A. Filter fabric shall be Supac Style 5-NP, Trevira Spunbound Type S-1115, Amoco Style 4545, or
an approved equal.The Contractor shall furnish the Engineer sufficient data to evaluate the ade-
quacy of any substitute non-woven filter fabric. No installation of substitute fabric shall be per-
mitted until written approval has been furnished by the Engineer.
2.7 STRUCTURES:
A. MANHOLES
1. Normal-Traffic Precast Concrete Manholes: ASTM C 478(ASTM C 478M),precast,
4000 psi reinforced concrete, of depth indicated,with provision for rubber gasketed
joints.
a) Diameter: 48 inches(1200 mm)minimum,unless otherwise indicated.60
inches minimum for NPS 21 and larger.
b) Ballast: Increase thickness of precast concrete sections or add concrete to base
section,as required to prevent flotation.
c) Base Section: 6-inch(150-mm)minimum thickness for floor slab and 5-inch
(100-mm)minimum thickness for walls and base riser section,and minimum 6-
inch(150—mm)extended base with a minimum 12-inch class 57 stone bedding.
d) Riser Sections: 5-inch(100-mm)minimum thickness,and lengths to provide
depth indicated.
e) Top Section: Eccentric-cone type,unless concentric-cone or flat-slab-top type is
indicated. Top of cone of size that matches grade rings.
f) Gaskets: ASTM C 443 (ASTM C 443M),rubber.
g) Grade Rings: Include maximum of two reinforced-concrete rings,6-inch(150-
mm)total thickness,that match 24-inch-(610-mm-)diameter frame and cover.
h) Steps: Manufactured from deformed,3/4-inch steel reinforcement rod comply-
ing with ASTM A 615/A 615M and encased in polypropylene complying with
ASTM D 4101. Include pattern designed to prevent lateral slippage off step.
Cast or anchor into sidewalls with steps at 12-to 16-inch(300-to 400-mm)in-
tervals.
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i) Pipe Connectors:ASTM C 923 (ASTM C 923M),resilient,of size required, for
each pipe connecting to base section.All associated hardware shall be either cast
iron or stainless steel.
2. Heavy-Traffic Precast Concrete Manholes:ASTM C 913;designed according to
ASTM C 890 for A-16,heavy-traffic, structural loading;of depth,shape,and dimensions
indicated,with provision for rubber gasketed joints.
a) Ballast: Increase thickness of one or more precast concrete sections or add con-
crete to structure,as required to prevent flotation.
b) Gaskets: Rubber.
c) Grade Rings: Include a maximum of two reinforced-concrete rings,of 6-inch
(150-mm)total thickness,that match 24-inch-(610-mm-)diameter frame and
cover.
d) Steps: Manufactured from deformed,3/4-inch steel reinforcement rod comply-
ing with ASTM A 615/A 615M and encased in polypropylene complying with
ASTM D 4101. Include pattern designed to prevent lateral slippage off step.
Cast or anchor into sidewalls with steps at 12-inch intervals.
e) Pipe Connectors: ASTM C 923(ASTM C 923M), resilient,of size required, for
each pipe connecting to base section.All associated hardware shall be either cast
iron or stainless steel.
3. Brick manholes: Brick manholes must be built in accordance with City of Wilmington
Standard Detail 2-03, of brick free from cracks and defects that would impair their
strength or usefulness with cement mortar as specified.
a) Manholes will have six (6) inch Class A Concrete bottoms having a minimum
diameter of twelve (12) inches larger than the outside diameter of the structure,
upon which pipe will be laid as instructed by the Engineer.
b) Inverts shall be installed to suit the needs of each location.
c) Manholes must be at least four(4) feet inside diameter at the bottom. Manholes
for NPS 21 and larger shall be five (5) feet inside diameter. Where more than
four (4) feet deep, have steps twelve (12) inches apart, beginning two (2) feet
from the bottom and ending three (3) feet from the top of the manhole directly
below the access point. Where more than four (4) feet above finished ground,
steps shall be provided as specified on the outside of the manhole. The steps
shall be set in the masonry as the work is built up, thoroughly banded and accu-
rately spaced and aligned. Where the depth of the manhole exceeds eight (8)
feet,the inside diameter of the manhole shall be increased to five(5)feet and the
wall thickness shall be increased to twelve (12) inches for the portion of the
manhole greater than eight(8)feet deep.
d) Masonry Cement: ASTM C91, Type 11 of a brand approved by the engineer, to
be newly manufactured,well housed,and kept dry and protected at all times.
4. Cast-in-Place Concrete Manholes: Construct of reinforced-concrete bottom, walls, and
top; designed according to ASTM C 890 for A-16, heavy-traffic, structural loading; of
depth,shape,dimensions,and appurtenances indicated.
a) Ballast: Increase thickness of concrete,as required to prevent flotation.
b) Grade Rings: Include a maximum of two reinforced-concrete rings, of 6-inch
(150-mm) total thickness, that match 24-inch- (610-mm-) diameter frame and
cover.
c) Steps: Manufactured from deformed, 3/4-inch (13-mm)steel reinforcement rod
complying with ASTM A 615/A 615M and encased in polypropylene complying
with ASTM D 4101. Include pattern designed to prevent lateral slippage off
step. Cast or anchor into sidewalls with steps at 12-inch intervals. Omit steps
for manholes less than 60 inches(1500 mm)deep.
5. Manhole Cover Inserts: Manufactured, solid, plastic form, of size to fit between manhole
frame and cover and designed to prevent stormwater inflow. Include handle for removal
and gasket for gastight sealing. Covers shall be secured with a minimum of four (4) 2-
inch lug bolts.
B. CATCH BASINS AND JUNCTION BOXES
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1. Normal-Traffic, Precast Concrete Catch Basins and Junction Boxes: ASTM C 478
(ASTM C 478M), precast, reinforced concrete, of depth indicated, with provision for
rubber gasketed joints.
a) Base Section: 6-inch minimum thickness for floor slab and 5-inch minimum
thickness for walls and base riser section, and having separate base slab or base
section with integral floor with a minimum 12-inch class 57 stone bedding._
b) Riser Sections: 5-inch minimum thickness, 48-inch diameter, and lengths to
provide depth indicated.
c) Top Section: Eccentric-cone type, unless concentric-cone or flat-slab-top type is
indicated. Top of cone of size that matches grade rings.
d) Gaskets: ASTM C 443 (ASTM C 443M),rubber.
e) Grade Rings: Provide a maximum of two reinforced-concrete rings, of 6-inch
total thickness,that match 24-inch-(610-mm-)diameter frame and grate.
f) Steps: Manufactured from deformed, 3/4-inch steel reinforcement rod comply-
ing with ASTM A 615/A 615M and encased in polypropylene complying with
ASTM D 4 10 1. Include pattern designed to prevent lateral slippage off step.
Cast or anchor into sidewalls with steps at 12-inch intervals.
g) Pipe Connectors: ASTM C 923 (ASTM C 923M), resilient, of size required, for
each pipe connecting to base section.
2. Heavy-Traffic, Precast Concrete Catch Basins and Junction Boxes: ASTM C 913, pre-
cast, reinforced concrete; designed according to ASTM C 890 for A-16, heavy-traffic,
structural loading; of depth, shape, and dimensions indicated, with provision for rubber
gasketed joints.
a) Gaskets: Rubber.
b) Grade Rings: Provide a maximum of two reinforced-concrete rings, of 6-inch
total thickness,that match 24-inch-(610-mm-)diameter frame and grate.
c) Steps: Manufactured from deformed, 3/4-inch steel reinforcement rod comply-
ing with ASTM A 615/A 615M and encased in polypropylene complying with
ASTM D 4 10 1. Include pattern designed to prevent lateral slippage off step.
Cast or anchor into sidewalls with steps at 12-inch intervals.
d) Pipe Connectors: ASTM C 923 (ASTM C 923M), resilient, of size required, for
each pipe connecting to base section.
3. Cast-in-Place Concrete, Catch Basins and Junction Boxes: Construct of reinforced con-
crete; designed according to ASTM C 890 for structural loading; of depth, shape, dimen-
sions,and appurtenances indicated.
a) Bottom,Walls,and Top:Reinforced concrete.
b) Channels and Benches: Concrete.
c) Steps: Manufactured from deformed, 3/4-inch steel reinforcement rod comply-
ing with ASTM A 615/A 615M and encased in polypropylene complying with
ASTM D 4101. Include pattern designed to prevent lateral slippage off step.
Cast or anchor into sidewalls with steps at 12-inch intervals.
d) Rectangular Frames and Grates: ASTM A 536, Grade 6040-18, ductile iron de-
signed for heavy-duty service. Include flat grate with small square or short-
slotted drainage openings.
(1) Size: 24 by 24 inches (610 by 610 mm) minimum, unless otherwise
indicated.
(2) Grate Free Area: Approximately 50 percent,unless otherwise indicated.
e) Circular Frames and Grates: ASTM A 536, Grade 60-40-18, ductile iron de-
signed for heavy-duty service. Include 24-inch (610-mm) ID by 7- to 9-inch
(178- to 229-mm) riser with 4-inch (100-mm) minimum width flange, and 26-
inch- (660-mm-) diameter flat grate with small square or short-slotted drainage
openings.
(I) Grate Free Area: Approximately 50 percent,unless otherwise indicated.
C. STORMWATER INLETS
I. Curb Inlets: Made with vertical curb opening, of materials and dimensions according to
City of Wilmington and/or NCDOT standards.
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2. Gutter Inlets: Made with horizontal gutter opening, of materials and dimensions accord-
ing to City of Wilmington and/or NCDOT standards. Include heavy-duty frames and
grates.
3. Combination Inlets: Made with vertical curb and horizontal gutter openings, of materials
and dimensions according to City of Wilmington and/or NCDOT standards. Include
heavy-duty frames and grates.
4. Frames and Grates: Heavy-duty frames and grates according to City of Wilmington
and/or NCDOT standards.
5. ADS Drop Inlet: 24"ADS PVC inline drain (or approved equivalent), with standard H-
20 rated cast iron surface grate and watertight pipe adapters.
2.8 CONCRETE
A. General: Cast-in-place concrete according to ACI 318,ACI 350R,and the following:
1. Cement: ASTM C 150, Type I or III.
2. Fine Aggregate: ASTM C 33,sand.
3. Coarse Aggregate: ASTM C 33 crushed gravel.
4. Water: Potable.
B. Portland Cement Design Mix: 4000 psi (27.6 MPa) minimum, with 0.45 maximum water-
cementitious materials ratio.
1. Reinforcement Fabric: ASTM A 185,steel,welded wire fabric,plain.
2. Reinforcement Bars:ASTM A 615/A 615M,Grade 60(Grade 400),deformed steel.
C. Structure Channels and Benches: Factory or field formed from concrete. Portland cement design
mix,4000 psi(27.6 MPa)minimum,with 0.45 maximum water-cementitious ratio.
1. Include channels and benches in manholes and catch basins.
a) Channels: Concrete invert, formed to same width as connected piping, with
height of vertical sides to three-fourths of pipe diameter. Form curved channels
with smooth, uniform radius arid slope. Invert Slope: 2 percent through manhole
or as indicated on the plans.
b) Benches: Concrete,sloped to drain into channel. Slope: 8 percent.
D. Ballast and Pipe Supports: Portland cement design mix,3000 psi(20.7 MPa)minimum, with 0.58
maximum water-cementitious ratio.
1. Reinforcement Fabric: ASTM A 185,steel,welded wire fabric,plain.
2. Reinforcement Bars: ASTM A 615/A 615M,Grade 60(Grade 420),deformed steel.
2.9 MORTAR
A. Mortar shall be prepared from cement,sand and water of an approved source. Mortar shall consist
of one(1)part by volume of Portland cement and three(3)parts by volume of sand.
2.10 BACKWATER VALVES
A. Gray-Iron Backwater Valves: ASME A112.14.1,gray-von body and bolted cover, with bronze
seat.
B. Horizontal Type: With swing check valve and hub-and-spigot ends.
C. Combination Horizontal and Manual Gate-Valve Type: With swing check valve, integral gate
valve,and hub-and-spigot ends.
D. Terminal Type: With bronze seat,swing check valve,and hub inlet.
E. PVC Backwater Valves: Similar to ASME A112.14.1,horizontal type;with PVC body,PVC re-
movable cover,and PVC swing check valve.
2.11 CLEANOUTS
A. Gray-Iron Cleanouts:ASME A 112.36.2M,round,gray-iron housing with clamping device and
round,secured,scoriated,gray-iron cover. Include gray-iron ferrule with inside caulk or spigot
connection and countersunk,tapered-thread,brass closure plug. Use units with top-loading classi-
fications according to the following applications:
I. Light Duty: In earth or grass foot-traffic areas.
2. Medium Duty: In paved foot-traffic areas.
3. Heavy Duty: In vehicle-traffic service areas.
4. Extra-Heavy Duty: In roads.
5. Sewer PipeFitting and Riser to Cleanout: ASTM A 74,Service class,cast-iron soil pipe
and fittings.
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B. PVC Cleanouts: PVC body with PVC threaded plug. Include PVC sewer pipe fitting and riser to
cleanout of same material as sewer piping.
2.12 CHANNEL LININGS:
A. Concrete filled fabric forms: Fabric forms for concrete lined channels shall consist of double layer,
open-selvage fabric joined in a mat configuration. Each layer shall exhibit minimum grab ten-
sile strength of not less than 200 lbs/in in both warp and full directions when tested in
accordance with ASTM Specification D-2682 and a porosity of not less than 100cf/min/ft
when tested in accordance with ASTM Specification D-737. The fabric , forms shall be joined
together by interwoven ties of uniform length. Hydrostatic uplift relief shall be provided and in-
stalled in accordance with the manufacturer's recommendation. Grout stops shall be installed par-
allel to the mill width at predetermined intervals to regulate the flow of grout.
B. Rip Rap: Rip rap shall be installed at the locations shown on the plans or as directed by the Engineer.
All rip rap shall be installed at a thickness of two(2)feet and shall be installed with non-woven filter
fabric resistant to ultraviolet rays between the ground and the rip rap unless noted otherwise on the
plans. Rip rap shall consist of field stone or rough unhewn quarry stone. The stone shall be sound,
tough,dense,resistant to the action of air and water,and suitable in all other respects for the purposes
intended.The stone shall be graded to meet the following requirements:
1. Class I - Stone shall vary in weight from 5 to 200 pounds with at least 30% of the total
weight of rip rap weighing a minimum of 60 lbs.and not more than 10%weighing less than
15 lbs.
2.. Class 11-Stone shall vary in weight from 25 to 250 lbs.with at least 60%of the total weight
of the rip rap shall weigh a minimum of 100 lbs. and no more than 5%shall weigh less than
50 lbs.
3. Class A-Stone shall vary in size from 2-inches to 6-inches and while no specific gradation
is specified,the stone shall be equally distributed within the range. The size shall be deter-
mined by measuring its long dimensions.
4. Class B-Stone shall vary in size from 5-inches to 15-inches and while no specific grada-
tion is specified,the stone shall be equally distributed within the range. The size shall be
determined by measuring its long dimensions.
2.13 SUBDRAINS:
A. Subdrains shall be installed as shown on the plans or as directed by the Engineer. Unless otherwise
specified, the subdrains shall be installed in accordance with City of Wilmington Standard Detail
2-04.
B. Subdrain Pipe: Subdrain pipe shall be six (6) inch perforated pipe with the perforations on the
bottom of the pipe. Metal subdrain pipe shall be galvanized corrugated steel pipe meeting ASTM
A-760 and. AASHTO M-36. PVC Subdrain pipe shall be Schedule 40 meeting the requirements
of ASTM Specification D-1785.
2.14 CRUSHED STONE: Crushed stone for pipe bedding shall conform to ASTM C33,size#57.
2.15 STORMWATER INFILTRATION SYSTEMS
A. Storage and Leaching Chambers: Molded HDPE perforated pipe with perforated. Include number
of pipes,distribution piping,end sections,fittings,and other standard components as required for
system total capacity.
B. Filtering Material:ASTM C33,size#57 washed,crushed stone.
C. Filter Fabric:Geotextile woven or spun filter fabric, in one or more layers, for minimum total unit
weight of 4 oz./sq. yd.(135 g/sq.m).
PART 3-EXECUTION
3.1 GENERAL
A. Prior to beginning any work, the contractor shall consult with the Engineer and Owner to verify
that all applicable permits, easements and rights-of-way have been obtained and that all other le-
galities are in order. He shall familiarize himself with all conditions, limitations and requirements
of such permits, easements and rights-of-way and stay in full compliance throughout the contract
period. All work shall be confined to the rights-of-way, easement,permit and property limits. Any
encroachment beyond these limits shall be the Contractor's liability.
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B. Storm Drainage system components shall be installed at the locations shown on plans to the lines
and grades indicated thereon.
C. Install pipe, gaskets, seals, sleeves, and couplings in complete accordance with manufacturer's
written instructions for using lubricants, cements,and other installation requirements. Where those
recommendations differ from these specifications,the most conservative shall govern.
3.2 PIPING APPLICATIONS
A. General: Use pipe, fittings, and joining methods for piping systems according to the plans and the
following applications:
I. Reinforced concrete pipe for all storm drainage except where an alternate is indicated on
the plans.
2. HDPE for infiltration systems unless an alternate is approved by the engineer.
3.3 CLEARING AND GRUBBING
A. Clearing and grubbing shall be done prior to beginning of pipe installation. It shall be done in ac-
cordance with applicable portions of items of the General Conditions.
B. The Contractor shall consult with the Owner and Engineer prior to starting clearing and grubbing
in order to reach a full understanding of the required procedure. The Contractor shall then conduct
clearing and grubbing operations in strict accordance with the agreed upon procedure.
C. Clearing and grubbing shall be performed in accordance with Section 02230-Site Clearing.
3.4 TRENCH EXCAVATION
A. Trenches for pipe shall be dug true to line and grade and to the following requirements: Depth of
cover shall not be less than 3'-0" for pipe up to 8" in diameter and 3'-6" for pipe 10" and larger in
diameter,measured to the top of pipe,unless shown differently on the profile or authorized by the
Engineer.
B. Sides of trenches shall be kept as nearly vertical as possible within the allowances of the Occupa-
tional Safety and Health Administration. They shall be at least 12" and not more than 24"wider at
the top of the pipe than the outside diameter of the pipe, plus sheathing where it is necessary.
Where paving is to be cut, it shall be cut in advance of trenching 12" wider than the specified
width of the trench.
C. Where soil conditions prohibit vertical walls,the trench width at the bottom and at I'above the top
of the pipe shall be as specified above with the remainder being held to the least possible width
greater than that specified. Where soil conditions prevent ditch excavation without excessive
widths,or where directed by the Engineer,wood sheeting, as hereinafter specified, shall be driven
to support the trench walls,or a suitably reinforced steel trench box shall be employed.
D. Trench bottoms shall be graded to provide a firm class"C" foundation with uniform and continu-
ous along the entire length of the pipe. Bell holes shall be dug for pipe bells to relieve the bells of
load. No ridges, sags, or undercutting will be allowed. Ledge rock, boulders, and large stones
shall be removed to provide a minimum clearance of 4"below and on each side of the pipe(s).Ex-
cess excavating below grade shall be backfilled at the Contractor's expense with suitable material.
Backfill shall be compacted to ninety-five (95)percent of maximum density obtained at optimum
moisture content,as determined by the ASTM D 698 Standard Proctor Test Method.
E. Where unstable, soft material is encountered at grade, as determined by the engineer, the trench
shall be excavated below grade. A minimum of 6" of class 57 stone shall be placed to grade to
form a firm stable foundation and uniform bearing for pipe. Bell holes shall be provided as previ-
ously specified. Material excavated from the trench that is unsuitable for backfill material shall be
disposed of off site by the contractor. The Contractor shall provide and place select borrow mate-
rial to replace unsuitable material for backfilling the trench as directed.
F. Where ground water is encountered in the bottom of the trench, causing the trench bottom to be
unstable as determined by the engineer,the material shall be excavated and backfilled as specified
for unsuitable material. The Contractor shall furnish all machinery for pumping, bailing, and/or
well pointing and shall pump, bail, or otherwise remove any water which may be found or shall
accumulate in the trenches,and shall perform all work necessary to keep them clear of water while
the pipe is being laid. The disposal of water after removal shall be satisfactory to the Engineer.
G. Whenever necessary,the side of the trench shall be braced and rendered secure and either open or
closed sheeting used in conformance with the latest Department of Labor Safety and Health
Regulations for construction promulgated under the Occupational Safety and Health Act of 1970.
In lieu of sheeting, suitable trench boxes may be employed.The installed pipe and its embedment
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shall not be disturbed when using moveable trench boxes. No extra payment will be made for
sheeting and bracing. Such cost shall be included in the cost of installing the pipe.
H. All existing water, sewer, and gas lines, buried electrical and telephone cable, and other known
utilities intersecting the lines of construction shall be uncovered by the Contractor at his expense
and exposed to the Engineer at least 100'ahead of pipe laying operations of insure the correctness
of grades, if requested by the Engineer. Existing utilities shown on the Plans are as accurately lo-
cated as existing records and field surveys allow; however, the Contractor shall verify with the
various utility companies before excavating and shall save harmless the Owner from any claims
for damages as a result of this work.
I. The Contractor shall at all times take necessary precautions in preventing gutters, catch basins,
ditches and other drainage facilities from being clogged that might cause flooding conditions and
damage to public or private properties.
J. If ledge rock,hard pan,shale, or other unyielding material is encountered,the Contractor shall no-
tify the engineer immediately, prior to excavation. The material shall be excavated at least 6" be-
low subgrade elevation. The trench shall be brought to grade with select material compacted in
place as specified for ordinary excavation. Only solid rock requiring blasting or drilling for its
removal will be classified as rock excavation. No additional payment will be made for rock exca-
vation which is not approved by the engineer prior to excavation.No blasting shall take place prior
to approval of the engineer.
3.5 PIPE INSTALLATION
A. General
1. Pipe and appurtenances shall be shall be carefully handled to prevent damage and distrib-
uted neatly along the trench prior to installation. Mechanical hoists or other approved
methods shall be used in the handling. Pipe or fittings shall be protected during handling
against impact shocks and free fall. Pipe shall not be dumped or rolled into the trench, or
dropped against the pipe or fitting already in the trench.Care shall be taken to prevent the
pipe lining and coating from being damaged, and any lining or coating damaged in any
way shall be repaired by the Contractor to the satisfaction of the Engineer.
2. Pipe shall be installed to the lines and grades indicated on the plans. Install piping begin-
ning at low point with unbroken continuity of invert. The pipe shall be uniformly bedded
on the bottom of the trench for its entire length. Bell holes shall be provided in the pipe
bedding large enough to allow proper bedding and jointing. Jointing shall conform to the
manufacturer's recommendations for assembly of joint components, lubrication and
making of joints. Spigots shall be fully seated in the bells using methods approved by the
manufacturer and engineer.
3. Use manholes for changes in direction, unless fittings are indicated. Use fittings for
branch connections unless direct tap into existing sewer is indicated.
4. Install gravity-flow piping and connect to building's storm drains, of sizes and in loca-
tions indicated.
5. Cutting of a pipe when necessary, shall be done in a satisfactory manner with an ap-
proved cutting tool which will leave a smooth end at right angles to the axis of the pipe.
Cutting shall not otherwise damage the pipe or liner. Such cuts shall be made by the
Contractor without extra compensation.
6. Minimize localized loadings and differential settlement wherever the pipe crosses other
utilities or subsurface structures. A cushion of bedding shall be provide between the pipe
and any such point of localized loading.
7. All water entering the excavations or other parts of the work shall be removed until all
the work has been completed.
8. Depth of cover shall not be less than 3'-0" for pipes 8" in diameter or 3'-6" for pipes 10"
and larger in diameter, measured to the top of pipe, except where shown differently on a
profile or specifically authorized by the Engineer.
9. When pipe laying in interrupted, the open ends shall be sealed to prevent the entrance of
mud,water,animals,or other foreign matter.
10. Extend storm drainage piping and connect to building's storm drains, of sizes and in lo-
cations indicated. Terminate piping as indicated.
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11. The Contractor shall be responsible for and correct any and all defects due to settlement,
poor workmanship,improper handling,or lack of maintenance.
12. It shall be the Contractor's responsibility to maintain the new and existing pipe system as
well as existing utilities on the job site for the duration of the project. This is to include, but
not be limited to,the infiltration of sand and debris into the new and existing storm drainage
system and into the other utility lines. Should sand or debris collect in any portion of the
new or existing systems as a result of construction, the Contractor shall be required to re-
move said sand and debris at his own expense.
B. Reinforced Concrete Pipe(RCP)
1. RCP shall be installed in accordance with the American Concrete Pipe Association
(ACPA) guidelines. Class C bedding shall be used. The subgrade shall be shaped to fit
the lower part of the pipe exterior for a width of at least 50 percent of the outside diame-
ter for a circular pipe, and one-tenth of the outside pipe rise for arch pipe, elliptical pipe,
and box sections. A granular foundation shall be used only with circular pipe and shall
consist of a compacted granular material or densely compacted backfill placed on a flat
bottom trench.
C. Corrugated Polyethylene Pipe(CPP)
1. Pipe shall be of the sizes, types, and dimensions shown on the plans and shall include all
connections and joints to new or existing pipes, sewer manholes, inlets, headwalls and
other appurtenances as may be required to complete the work.
2. Corrugated polyethylene pipe shall be installed in accordance with the plans and specifi-
cations,manufacturer's guidelines and ASTM D-2321.
3. Shaping and Bedding: All shaping and bedding shall be in accordance with ASTM D —
2321 -"Excavation and Backfill for Structures".
4. Installation:
a) Unless otherwise authorized by the Engineer,the laying of pipes on the bedding
shall be started at the outlet end, the separate sections firmly joined together,
outside laps of annular joints pointing upstream and longitudinal laps on the
sides. Proper facilities shall be provided for hoisting and lowering the section of
pipe into the trench without damaging the pipe or disturbing the bedding and the
sides of the trench. Any pipe which is not in alignment or which shows any un-
due settlement after laying shall be taken up and relayed without extra compen-
sation.
b) Multiple installation of corrugated polyethylene pipe shall be laid with the cen-
ter lines of individual barrels parallel. Unless otherwise indicated on the plans,
the following clear distances between outer surfaces of adjacent pipes shall be
maintained:
Diameter Clear Distance <`* '
Of Pipe ' ,,.Between Pipes
18" 1'-2"
24" 1'-5"
30" 1'-8"
36"
42" 2'-2"
48" T-5"
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c) Culvert Connections: Where new structures are constructed as extensions to
structures in place or are joined to existing structures, the construction shall in-
clude all work necessary to provide a proper connection between the new struc-
ture and the existing as indicated on the plans.
d) Reuse of Existing Appurtenances
(1) When existing appurtenances are specified on the plans for reuse, the
portion to be reused shall be severed from the existing culvert and
moved to the new position previously prepared,by approved methods.
(2) Connections shall conform to the requirements for joining sections of
pipes as indicated herein or as shown on the plans. Any headwalls and
any aprons or pipe attached to the headwall that are damaged during
moving operations shall be restored to their original condition at the
Contractor's expense. The Contractor, if he so desires,may remove and
dispose of the existing headwalls and aprons and construct new head-
walls at his own expense, in accordance with the pertinent specifica-
tions and design indicated on the plans or as furnished by the Engineer.
e) Backfilling. Backfilling shall be in accordance with ASTM D-2321, "Excava-
tion and Backfill for Structures". Special emphasis is placed upon the need for
obtaining uniform backfill material and uniform compacted density throughout
the length of the structure so that equal pressure will be provided.As fast as the
material is placed, it shall be cut under the haunches of the pipe with a shovel
and thoroughly compacted with mechanical tamps for the full width of the
trench to provide support for the bottom and sides of the pipe.
D. PVC Pipe
1. Install PVC plastic pipe according to ASTM D 2321 and the recommendations of the
manufacturer.
2. Embedment materials shall be Classes I,II, or 11 as described in ASTM D 2321, for bed-
ding haunching and initial backfill, shall be used and carefully compacted for all flexible
pipe provided the proper strength pipe is used with the specified bedding to support the
anticipated load, based on the type of soil encountered and potential groundwater condi-
tions. Class 57 stone shall be used for bedding and haunching to the springline the pipe.
Bedding depth shall be a minimum of six(6)inches.
3. All PVC mains shall be fully encased in stone bedding when the depth equals or exceeds
eight(8)feet.
3.6 PIPE JOINT CONSTRUCTION AND INSTALLATION
A. General: Join and install pipe and fittings according to installations indicated.
B. RCP:Joints for reinforced concrete pipe shall be tongue and groove with flexible watertight joints
unless specified otherwise on the plans, specifications,or proposal or unless directed otherwise by
the Engineer. Jointing procedure shall be per ACPA and manufacturer guidelines. The joint mate-
rial shall be as recommended by the reinforced concrete pipe manufacturer and shall provide water
tight seals at all joints, meeting the requirements of ASSHTO M-198, ASTM C-990 and Fed.
Spec. SS-S-210A. Joint materials specifications shall be submitted to the Engineer for review and
approval prior to installation.
C. CMP: Corrugated metal pipe joints, fittings, and bands shall be manufactured, coated, and in-
stalled as specified by the pipe manufacturer. The joints,bands, and fittings shall receive the same
coatings as the pipe and shall be designed and installed to minimize infiltration. To accommodate
the corrugated bands, helically corrugated pipe shall be re-rolled at the ends to provide two annu-
lar corrugations. The inner corrugations shall accommodate two closed cell neoprene O'ring gas-
kets.
D. Aluminum corrugated pipe joints shall be in accordance with the manufacturers recommendation and
shall provide a water-tight seal at all joints. Specifications for joints and fittings for aluminum corru-
gated pipe shall be submitted to the Engineer for review and approval prior to installation.
E. PVC Sewer Pipe and Fittings: As follows:
1. Join pipe and gasketed fittings with gaskets according to ASTM D 2321.
2. Install according to ASTM D 2321.
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F. System Piping Joints: Make joints using system manufacturer's couplings, unless otherwise indi-
cated.
G. Join piping made of different materials or dimensions with couplings made for this application.
Use couplings that are compatible with and that fit both systems' materials and dimensions.
Adapters shall be furnished and installed as necessary when connections are made to other types
of pipe.
H. Install with top surfaces of components,except piping, flush with finished surface.
3.7 BACKFILLING
A. All trash, fortes, debris, and other foreign material shall be cleared from around all pipes and
structures before backfilling.
B. Backfilling of trenches shall be completed after the installation of each section of pipe. Backfill-
ing shall be kept up with the pipe laying to the satisfaction of the Engineer.
C. Backfill around the pipe,and to a depth of at least F above the top of pipe, shall be placed by hand
in layers of not over 6" and compacted to a minimum density of ninety-five (95) percent of the
maximum dry density as determined by ASTM D 1557 Standard Test Method. Only select mate-
rial containing no rocks, perishable material, or other objectionable material shall be used for this
portion of the backfill. As fast as the material is placed, it shall be cut under the haunches of the
pipe with a shovel and thoroughly compacted for the full width of the trench to provide support for
the bottom and sides of the pipe. Care shall be taken to prevent any disturbance to the pipe or the
newly made joints.
D. Backfilling shall be compacted and brought up evenly on both sides of the pipe in such a manner
as to prevent injurious side pressures.Heavy vibratory equipment shall not be permitted to operate
directly over the pipe until a minimum of three(3)feet of backfill has been placed above the pipe.
E. The balance of the backfill shall be placed and tamped to prevent excessive settlement in a manner
satisfactory to the Engineer.
F. Trenches that are located under miscellaneous paved areas, areas to be paved, or unpaved streets
shall be backfilled with suitable material free from large stones or clods in 6" layers (loose meas-
urement) and thoroughly tamped and compacted to 95% of maximum dry density as established
by AASHTO Specification T99, Method A, with mechanical tampers to avoid future settlement.
Where applicable, the compaction shall be acceptable to the Department of Transportation or
Owner. For trenches located in streets and highways, trench backfilling shall be in accordance
with the requirements of item 3.10 of this section,"Cutting and Replacing Pavement."
G. For pipe outside street limits, compaction shall be at least 90%of maximum dry density as estab-
lished by AASHTO Specification T99,Method A.
H. Excess material shall be promptly removed from the site, and any pavement or road surface
cleaned of objectionable material. The pavement and/or road surface shall be cleaned daily with a
mechanical broom to the satisfaction of the engineer or Department of Transportation officials.
I. In unpaved streets, the top 6" of trench shall be filled with well compacted NCDOT ABC. In
paved areas,the top of the trench shall be filled with the specified base for pavement, well mixed
and compacted. Any settlement of backfill below finish grade shall be promptly corrected.
J. The Contractor will be responsible for settlement in all trenches and shall leave trenches flush with
the original ground after all settlement has taken place. Trenches must be protected against scour
due to surface drainage. The Contractor shall correct any future settlement within the guarantee
period at his own expense.
3.8 CUTTING AND REPLACING PAVEMENT
A. Where pavement is to be cut for installation of pipe or other utilities, the Contractor shall cut it
neatly to a straight edge in advance of trenching with the method of cutting being subject to ap-
proval of the Engineer. Pavement shall be cut 12" wider than the excavated area on each side.
Ragged or irregular edges will not be allowed and work completed with barred edges shall be re-
done. Concrete pavement shall be sawed with suitable concrete saw cutting equipment.
B. Trench backfilling shall be done in layers not over 6" thick and compacted to prevent future set-
tlement. Compaction shall be such as and shall be done by acceptable means, approved by the
Engineer. Rolling with rubber tired vehicles or track-type equipment will not be allowed. Com-
paction shall be to at least 95% of maximum density as established by AASHTO Specification
T99, Method A
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C. Base for pavement shall be ABC stone for all non-NCDOT maintained streets, HB binder for all
secondary highways,and reinforced concrete for all primary highways. All base shall be placed in
accordance with plan and/or encroachment permit details. Base width shall be as shown on the
plans and/or encroachment permits for various types of pavement cuts.
D. ABC stone shall conform to the requirements of Section 02231. It shall be well mixed and com-
pacted by tamping and rolling. ABC base material shall be placed at the same time that the trench
is backfilled. Backfilling to top of trench,to be cut out and replaced with base material at a later
date,will not be allowed.
E. ABC stone base for highway pavement and adjacent drives shall be 8" of stone, stabilized with 5%
Portland Cement. It shall be thoroughly mixed prior to compacting.
F. ABC stone base for non-highway pavement and drives shall be 8" of stone without the addition of
cement.
G. Binder base for secondary roads shall be a minimum of 6" HB binder conforming to specifications
of the Department of Transportation.
H. Concrete base shall consist of 8" of concrete,reinforced with #4 reinforcing steel bars placed at 8"
on center in the transverse direction and#4 tie bars in the longitudinal direction. Concrete shall be
designed to produce a compressive strength of 3000 psi at 28 days. The design of the mix and
source of supply shall be subject to approval of the Engineer.
1. Pavement shall be replaced with the same type of pavement that exists prior to cutting and shall
consist of either bituminous surface course (double treatment), 2" of hot plant mix asphaltic con-
crete, or 8" of Portland Cement concrete; all conforming to specifications of the Department of
Transportation for each type.
J. All pavement shall be repaired within the same week that it is cut. Should inclement weather de-
lay pavement replacement, the Contractor shall not cut additional pavement until he has notified
the Engineer and received specific permission and instructions.
K. For asphalt pavement or bituminous surfacing, the entire area to be resurfaced(including edges of
existing pavement)shall be primed with an acceptable asphalt prime coat just prior to placing new
pavement.
3.9 CONCRETE REMOVAL AND REPLACEMENT,PROTECTION CONCRETE
A. Where pipe is to be placed under existing concrete drives or sidewalk, the concrete shall be re-
moved in construction units unless their length is more than 10', in which case the concrete shall
be cut as specified in paragraph 3.9.A.of this section. The backfill shall be thoroughly compacted
for the entire depth of the trench.
B. Drives and sidewalks shall be replaced with 3000 psi concrete,6"thick for driveways and 4"thick
for sidewalks. The concrete shall be placed monolithic and dressed off with a wooden float,brush
and edging tool. Where pipe is to be placed under concrete drive or sidewalk,the Contractor may,
with the permission of the Engineer, install the pipe by tunneling instead of removing and replac-
ing the drive or walk. If pipe is to be placed under curb and gutter, it shall be done by tunneling.
No additional payment will be made therefore.
C. Protection concrete shall be poured at the locations and to the dimensions as indicated on the plans
or as directed by the engineer. Protection concrete shall consist of one part Portland Cement, two
parts sand,and four parts crushed stone.
D. Place all cast-in-place concrete according to AC► 318 and ACI 350R.
3.10 STRUCTURES
A. All structures shall be constructed on firm, undisturbed soil at locations shown on the plans or as
directed by the Engineer,provided that all precast structures shall have a minimum of twelve (12)
inches of washed stone (#57) bedding and the cost of the stone bedding shall be considered inci-
dental to the precast structure. Where the Contractor undercuts the soil for the footing, the Con-
tractor shall be required to use washed stone(#57)to bring the subgrade back to proper elevation.
Should the contractor encounter unsuitable material at the subgrade elevation for the manhole
footing,he shall immediately notify the Engineer and assist the Engineer in determining the se-
verity of the problem and work with the Engineer in resolving the situation.
B. The inverts of all structures shall be constructed and shaped to provide free flow of water without
ponding and to eliminate and prevent accumulation of sediment and debris.
3.11 MANHOLE INSTALLATION
A. General: Install manholes,complete with appurtenances and accessories indicated.
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B. Form continuous concrete channels and benches between inlets and outlet.
C. Set tops of frames and covers flush with finished surface of manholes that occur in pavements.
Set tops 3 inches(76 mm)above finished surface elsewhere, unless otherwise indicated.
D. Install precast concrete manhole sections with gaskets according to ASTM C 891 and the follow-
ing:
I. Precast base sections shall be installed on stabilized foundation as indicated on the plans
so prepared to prevent settlement and misalignment. Pipe openings shall be exactly
aligned to that of the pipe entering and leaving the manhole.
2. Pipe connections shall be cut off flush with the inside wall of the drainage structure and
grouted as necessary to make smooth and uniform surfaces of the inside of the structure.
Connections shall be water tight and shall be grouted from both the interior and exterior
of the structure.
3. Rubber ring joints or semi-rigid composition joints shall be carefully made in accordance
with the manufacturer's instructions. Bells shall be wiped clean, be free of all dirt or
other matter, and liberally lubricated for receiving the spigot ends. The gasket groove
and gasket shall be well cleaned and lubricated prior to placing.
4. Cement mortar joints shall be carefully made to the manufacturer's requirements. Grout
shall be as stiff as possible to be consistent with good practice and all joints shall be well
filled.
5. Where PVC pipe is used, pipe shall be placed in the openings provided in the base sec-
tion and properly aligned and set to grade. They shall be firmly held in place by the
flexible coupling and the base opening shall be filled with an expanding type grout well
rammed into place.
6. Steps shall be properly placed at 12" intervals and to the other requirements specified for
brick manholes.
7. Cast iron frames and covers shall be properly set in a bed of mortar and aligned to fit the
top section of the manhole.
8. The City of Wilmington reserves the right to reject any structure which has been dam-
aged and could result in a loss of structural strength or integrity
E. Brick Manholes
1. All brick must be thoroughly soaked with water before use.
2. The mortar must be so mixed and tempered that it will almost flow.
3. All brick when set must be all header course, pushed to a firm seating in mortar and all
joints well filled and spaded.
4. Manholes shall be plastered with cement mortar on the exterior and interior to a mini-
mum thickness of 3/4 inch.
5. After pipe is laid, concrete or brick inverts will be poured or shaped in the following
manner;if PVC pipe is used,the pipe shall run through the manhole on top of the footing.
Concrete or brick inverts shall be shaped so that the bottom half of the pipe shall be en-
tirely encased and the concrete or brick shall extend vertically from the spring line of the
pipe to a point level with the top of the pipe. From this point to the side of the manhole
there shall be a rise of at least four (4) inches. If bricks are used, each brick must be
pushed in the mortar and a layer of mortar at least three-quarters (3/4) inch thick must
cover all brick.After the invert has set up,the top of the pipe shall be broken out down
to the spring line of the pipe and the rough edges left at this point shall be pointed up in
such a manner as to give a smooth surface. In the cast iron pipe or pipe entering at an an-
gle to the direction of flow, the cross-section of the invert shall remain the same as de-
scribed above. There will be no pipe to form the bottom of the invert, but the brick or
concrete shall be shaped in the same manner, and shall be curved to conform to the di-
rection of flow into the manhole.
F. Construct cast-in-place manholes as indicated.
3.12 INTERFERENCE MANHOLES:
A. Installation of interference manholes shall be in accordance with the specifications for the type of
manhole being installed. The carrier pipe through the interference manhole shall always be metal
(steel or ductile iron). When the carrier pipe is an existing pipe to be replaced, the carrier pipe
shall be a separate bid item unless specifically stated otherwise on the plans or special conditions.
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A minimum of twelve (12) inches clearance shall be provided between the outside bottom of the
carrier pipe and the bottom of the manhole invert, said clearance may have to be a "sumped" area
in some cases. Steps shall be installed one(I)foot on center directly below the access opening.
3.13 REINFORCED CONCRETE JUNCTION BOXES:
A. Reinforced concrete junction boxes shall be constructed in accordance with the details on the
plans, specifications, and in accordance with the applicable sections of the latest edition of the
ACI Manual of Concrete Practices. All pipes entering or leaving the junction box shall be set prior
to the placing of the concrete for the walls. Steps shall be installed one (1) foot on center directly
below the access opening.
3.14 PRECAST REINFORCED CONCRETE JUNCTION BOXES:
A. All connections to the precast junction boxes shall be water tight and shall be sealed fromboth the
interior and exterior of the structure.Care shall be taken in handling,setting,and connecting to the
structure to prevent any structural damage. The City reserves the right to reject any structure
which has been damaged and could result in a loss of structural strength or integrity. Steps shall be
installed one(1)foot on center directly below the access opening.
3.15 BRICK CATCH BASINS:
A. Brick catch basins shall be constructed on concrete footing a minimum of six(6)inches thick and
extending a minimum of four(4) inches past the outside face of the structure. Brick catch basins
shall be plastered with % inch cement on both the exterior and interior of the structure. All brick
shall be whole,solid,uniform brick made of cement or hard burned clay. The brick shall be fully
soaked in water prior to being set in cement mortar. All pipes entering or leaving the catch basin
shall be set prior to the setting of bricks. Bricks and mortar shall be placed around the pipes in a
manner to ensure a neat water tight seal.
3.16 GRILL BASINS:
A. Grill basins shall be constructed on concrete footing a minimum of six(6)inches thick and ex-
tending a minimum of four(4)inches past the outside face of the structure. Brick grill basins
shall be plastered with%inch cement on both the exterior and interior of the structure. All brick
shall be whole,solid,uniform brick made of cement or hard burned clay. The brick shall be fully
soaked in water prior to being set in cement mortar. All pipes entering or leaving the grill basin
shall be set prior to the setting of bricks. Bricks and mortar shall be placed around the pipes in
a manner to ensure a neat water tight seal.
3.17 REINFORCED CONCRETE HEADWALLS:
A. Reinforced concrete headwalls shall be constructed of Class A concrete as specified in T-6.09 of
the concrete section of the specifications. All concrete shall comply with the requirements in Sec-
tion 6 of the specifications and with the applicable sections of the ACI Manual on Concrete
Practices.Reinforcing steel shall be Grade 60 Deformed bars complying with ASTM A - 615
and shall be of the size and quantity specified in the details and/or specifications. Steel shall be
placed in accordance with the details and specifications and shall be placed such that a minimum
of two(2)inches of concrete covers the steel.
3.18 FLARED END SECTIONS
A. All flared end sections shall be manufactured of the same material as the pipe to which it is being
connected. The flared end section shall be installed such as to minimize and prevent undermining
of the flared end section and to minimize erosion of the receiving channel. The Contractor shall
use extreme care not to undercut the soil under the flared end section. Where the soil is undercut,
the Contractor shall be required to replace the material and to place the material in six(6) inch lifts
achieving 100%of the maximum density at optimum moisture, as determined by ASTM D-1557
Standard Test Method.
3.19 CHANNEL LININGS:
A. Concrete Filled Fabric Forms
1. Concrete filled fabric forms shall be installed on a uniformly shaped ditch section (or
bank slope)which is sufficiently stable to hold its shape while the fabric is being placed,
filled, and cured. The ends of the fabric shall be tucked-in to the bank in accordance with
the manufacturer's recommendations but a minimum of 18 inches. Fabric forms shall
have filter points to allow the flow of ground water through the filled fabric or the fabric
forms shall be installed with weep holes. Filter points and weep holes shall both be de-
signed to allowed the flow of water while preventing sand or silt from moving through
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Copyright 1997 AIA MASTERSPEC 5/94
the fabric forms. The finished product shall be a uniformly shaped surface installed on
the grade and section specified in the plans and specifications and shall permit proper
flow of water without excessive ponding.
B. Rip Rap
1. Rip rap shall be installed at locations shown on the plans and shall be placed a minimum
of two (2) feet thick. All rip rap shall be placed on approved filter fabric. Placement of
the rip rap shall result in a uniform surface. The Contractor shall use caution to prevent
any tears or holes in the filter fabric when placing the rip rap. All tears or holes in the fil-
ter fabric shall be repaired as directed by the Engineer. As a minimum, the damaged area
shall have an undamaged section of filter fabric which extends a minimum of two(2) feet
in all directions past the damaged area,placed over the damaged filter fabric.
3.20 SUBDRAINS
A. Subdrains shall be installed at locations shown on the plans or as directed by the Engineer. The
sub-drain shall be installed in accordance with SD 2-04.A minimum of six (6) inches of washed
stone shall be placed around the perforated pipe. The washed stone shall be wrapped in an ap-
proved non-woven filter fabric. Unless directed otherwise, all subdrains shall be connected to the
storm drain system at structures and the invert of the subdrain shall be a minimum of six (6)
inches above the invert of the structure.
3.21 BACKWATER VALVE INSTALLATION
A. Install horizontal units in piping where indicated.
B. Install combination units in piping and in structures where indicated.
C. Install terminal units on end of piping and in structures where indicated. Secure units to structure
walls.
3.22 STORM DRAINAGE INLET AND OUTLET INSTALLATION
A. Construct inlet head walls,aprons,and sides of reinforced concrete,as indicated.
B. Construct riprap of broken stone,as indicated.
C. Install outlets that spill onto grade,anchored with concrete,where indicated.
D. Install outlets that spill onto grade,with flared end sections that match pipe,where indicated.
E. Construct energy dissipators at outlets,as indicated.
3.23 CONCRETE PLACEMENT
A. Place cast-in-place concrete according to ACI 318 and ACI 350R.
3.24 EXISTING PIPES AND STRUCTURES
A. Tapping Existing Structures
1. Where shown on the plans or directed by the Engineer,the Contractor shall connect new
pipe, install new structures,etc.or otherwise make connection to the existing storm drain
systems. This connection (tap)shall be accomplished with minimal damage to the exist-
ing structure. All gaps, cracks, etc. shall be mortared so as to prevent any ground-water
infiltration. This shall be accomplished with the type brick and mortar used in construc-
tion of new manholes unless otherwise specified or directed by the Engineer. NO
EXTRA PAYMENT SHALL BE ALLOWED FOR THIS WORK.
B. Replacement of Existing Structures
1. Where shown on the plans or directed by the Engineer, the Contractor shall replace an
existing structure with a new structure. Unless noted otherwise,the Contractor shall com-
pletely remove the old structure, including the footing and shall build the new structure in
accordance with the appropriate standards and specifications or as directed by the Engi-
neer.
C. Removal of Existing Pipe and/or Structures
1. Unless noted otherwise in the Special Conditions section or on the plans, the Contractor
shall remove ALL abandoned pipe and/or structures. Unless noted otherwise in the pro-
posal,NO EXTRA PAYMENT SHALL BE ALLOWED FOR THIS WORK.
D. Salvaging Existing Pipe,Castings,Etc.
1. All pipes, castings, etc. deemed salvageable by the Engineer shall be removed from the
construction site by the Contractor and shall be delivered to the City Lot Complex at
loth and Fanning Streets. Upon such delivery, the Contractor shall receive a receipt for
said salvaged material. The Contractor shall be required to replace all material directed to
be salvaged which he can not account for.
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Williston Middle School—Phase 11 Renovations

1
Copyright 1997 AIA MASTERSPEC 5/94
E. Plugging Existing Lines
1. The Contractor shall install a masonry plug where shown on the plans or directed by the
Engineer. Unless otherwise stated in the Special Conditions section or in the proposal,
NO EXTRA PAYMENT SHALL BE ALLOWED FOR THIS WORK.
F. Grout Filling abandoned Lines and/or Structures
1. Where shown on the plans, specified in the Special Conditions section,or directed by the
Engineer, the Contractor shall fill existing pipes and/or structures as required with con-
crete or grout. This concrete or grout shall be a minimum 2000 psi. For pipe, this grout
shall be pumped under pressure into the section being filled in such a manner to ensure
that the line completely fills with the concrete or grout.
3.25 REPAIRS TO DAMAGED UTILITIES AND SERVICES
A. Contractor shall promptly repair all damaged utilities and services at the Contractor's expense.
The Contractor shall use every effort to avoid damaging,breaking or otherwise interrupting water,
sewer, gas, power, telephone, or other utility service. Utility lines shall be properly supported
across the pipe trench until backfilling is completed. Should damage occur, immediate action
shall be taken to provide satisfactory repairs. All repair work shall be satisfactory to the Engineer
and Owner of the damaged utility.
3.26 FIELD QUALITY CONTROL
A. Clear interior of piping and structures of dirt and superfluous material as work progresses. Main-
tain swab or drag in piping,and pull past each joint as it is completed.
1. In large,accessible piping,brushes and brooms may be used for cleaning.
2. Place plug in end of incomplete piping at end of day and when work stops.
3. Flush piping between manholes and other structures to remove collected debris, if re-
quired by authorities having jurisdiction.
B. Inspect interior of piping to determine whether line displacement or other damage has occurred.
Inspect after approximately 24 inches(600 mm)of backfill is in place, and again at completion of
Project.
1. Submit separate reports for each system inspection.
2. Defects requiring correction include the following:
a) Alignment: Less than full diameter of inside of pipe is visible between struc-
tures.
b) Deflection: Flexible piping with deflection that prevents passage of ball or cyl-
inder of size not less than 92.5 percent of piping diameter.
c) Crushed,broken,cracked,or otherwise damaged piping.
d) Infiltration: Water leakage into piping.
e) Exfiltration: Water leakage from or around piping.
3. Replace defective piping using new materials, and repeat inspections until defects are
within allowances specified.
4. Reinspect and repeat procedure until results are satisfactory.
3.27 CLEANUP
A. Upon completion of backfilling and repair, all debris including but not limited to excess fill, bro-
ken concrete and pavement, rock, shoring and additional construction materials or waste shall be
removed and disposed of off site by the Contractor at his expense. Contractor shall comply with
all federal, state and local requirements for the disposal of waste. The work area shall be left clean
and in satisfactory condition to the Owner's and Engineer's approval.
B. Cleanup along highways, including grading, seeding and mulching, shall proceed with the work
immediately upon completion of backfilling. Pipe installation shall be stopped when cleanup work
does not proceed with installation. Installation shall not resume until cleanup progress is deemed
satisfactory by the engineer or owner. Final cleanup shall be subject to the approval of the Owner,
Engineer,and State Highway Representative.
C. Cleanup along cross country routes or on development sites shall follow immediately upon com-
pletion of any major part of the work or upon instructions by the Owner or Engineer. Topsoil shall
be removed, stockpiled, protected, respread and dressed off on all disturbed areas to the satisfac-
tion of the Owner and Engineer. All disturbed areas shall be revegetated as indicated on the plans
and specifications.
END OF SECTION 02630
STORM DRAINAGE 02530-20
Williston Middle School—Phase 11 Renovations

❑_® Kimley-Horn
e and Associates, Inc.
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May 5, 2000 ■
Suite 227
Mrs. Linda Lewis 4607 Franklin Avenue
NCDENR- DWQ - WiRO �) X���OS4 �D 28403gton,NonhCarolina
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127 Cardinal Drive `
Wilmington,NC 28405-3845
Re: Stormwater Permit Submittal for Williston Middle School Phase 11 M� \
Renovation New Hanover County,NC /
Stormwater Project No. SW8 990546
Dear Mrs. Lewis:
Sharpe Architecture has acquired the services of Kimley-Horn and Associates, Inc.
to design, permit, and oversee construction of stormwater for the Williston Middle
School Phase 11 Renovation.
Enclosed for your review, please find the following:
=> One (1) original and one (1) copy of the executed Stormwater Permit
Application
=> One (1)copy of the Wet Detention Basin Supplemental Form
=> The $420 Permit Application Processing Fee.
=> Two(2)copies of plans and applicable specifications
=> A detailed narrative description of the stormwater treatment and management
=:, Tabulations of existing and proposed impervious surfaces
=> Design calculations
Thank you for your assistance with this permit application review. Please contact
my office with any questions,comments or concerns.
Very truly yours,
KIMLEY-HORN AND ASSOCIATES, INC. RECEIVED
MAY 0 9'2000 �
J. Chris Ford, P.E.
cc: Mr.Neal Sauer, Sharpe Architecture
Mr. Carmen Gintoli,New Hanover County Schools
JCF/ajg
Enclosures
K APM0I 8047003\D W QS W I tr2.doc
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