SW7030307_HISTORICAL FILE_20090904

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW��`%
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
FHISTORICAL FILE
DOC DATE
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YYYYMM D D

t� Itive
&Associatesjnc.
Since1918
September 3, 2009
Ms. Amy Adams
NC Department of Environment, Health and Natural Resources
Division of Land Resources - Land Quality Section
943 Washington Square Mall
Washington, North Carolina 27889 SEP 4 ����
Subject: Eastern Elementary School
Washington, Beaufort County, North Carolina
Stormwater Management Permit No. SW7030307
Dear Ms Adams:
Engineers
Planners
Surveyors
Please accept this submittal in response to the Notice of Inspection addressed to Beaufort County
Schools dated August 31, 2009.
Enclosed for your review are the following:
1. Updated construction drawings showing the "as -built" condition
2. Engineer's Certification
Based upon my conversations with Mr. Phillip Boyd, the Beaufort County Schools' Facilities
Department will address the maintenance items noted in your report.
Please do not hesitate to call if you have any questions or need any additional information.
With best regards,
WAssociates, Inc.
/
F. Durward Tyson, J eP4E,
Project Manager
Enclosures
cc: Mr. Phillip Boyd, BCS w/enclosures
.107 ]fast Second Strcet. Greowille, NC: 27858 • Post Office Box 929 • Greenville, NC 27835 • [phone] • FAX [phone]
E-mail: [e-mail]

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Plivers
&Associates,lnc.
Since1918
September 3, 2009
Ms. Amy Adams
NCDENR Division of Water Quality
943 Washington Square Mall
Washington, NC 27889
Subject: Eastern Elementary School
Beaufort County, North Carolina
Stormwater Management Permit No. S W7030307
Dear Ms. Adams,
sEP 0 4 2009
Rivers and Associates, Inc. was authorized to provide construction administration services
consisting of weekly observation and monthly progress meetings during the construction of the
parking lot improvements at Eastern Elementary School for the Beaufort County Schools.
FIngineers
Planners
Surveyors
As a duly registered Professional Engineer in the State of North Carolina, 1 hereby state that to
the best of my knowledge and belief, due care and diligence was used in the observation of the
project construction such that the construction was observed to have been built within substantial
compliance and intent with the approved plans and specifications.
With best regards,
Rivers and Associates, Inc.
License No. F-0334
F. Durward Tyson, Jr., P.E.
Project Manager
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107 Elast Second Street, Greenville, NC 27858 • h st Office loos 929 • Greenville, NC 27835 • [phone] • FAX [phone],1
E-mail: ri%-crs@ri%,ers:uulassociatcs.com

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Beaufort County Schools
Eastern Elementary School
Parking Lot Improvements
Stormwater Management Plan
F. Durward T
Date
Washington, North Carolina
February 27, 2003
Ito,
�iAR - 5 2003
Brya C. Fagundu E.I.
Z/Z 7Zos
Date

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Beaufort County Schools
Eastern Elementary School
Parking Lot Improvements
Stormwater Management Plan
Washington, North Carolina
February 27, 2003
Eastern Elementary School is an expanding Pre-K through First Grade school with a
student population of 680 and 120 faculty members. With an expanding student body
and the resultant expansion of the faculty, traffic operations are an increasing safety
concern for the school. Presently, afternoon traffic presents a more threatening situation
for Eastern Elementary. Parents are arriving early to pick students up, parking or queuing
along the campus driveway or along an adjacent major through route. To alleviate this
problem, a proposed staff / faculty parking lot, a bus parking lot, and a travel lane for
student drop-off and pick-up are in the scope of this project.
The project area consists of 4.3± acres, which will include the faculty and bus parking
lots, the drop-off and pick-up travel lane and bioretention cells to treat stormwater runoff
from these areas. The proposed faculty parking lot will have 121 parking spaces,
including 4 handicap accessible spaces. The bus parking lot will provide parking for 10
buses while restricting vehicular access to this area. Additionally, a 28' travel lane will
be incorporated into the project to accommodate student drop-off and pick-up traffic. A
bioretention cell will be utilized to treat stormwater runoff from the additional impervious
surface created by the faculty / staff parking lot and the student drop-off 1 pick-up travel
lane. The proposed bus parking lot will sheet flow across the school lawn into existing
yard inlets.
The majority of the existing topography is flat, with the exception of the portion of
property to the south and west of the building. This area slopes sharply to the south.
Currently, to the south and west of the existing building, site drainage is achieved via
underground stormdrainage pipes, which collect stormwater from existing parking and
buildings. Two outlets daylight southwest of the existing building and staff parking lot,
then the runoff continues in a grass swale until the swale is piped under Pennsylvania
Avenue. Included in this pipe system to the southwest of the building is a 30" storm
drainage pipe coming onto the site from an adjacent street. Routing options for this
stormwater will be expanded upon later in this narrative. North of the building, site
drainage is achieved by sheet flow into two drop inlets. These inlets convey stormwater
into the NCDQT system on John Small Avenue (US Hwy 264). Native onsite soils
consist of fine, sandy loams in the Craven and Altavista varieties, both of which are
identified as being in hydrologic group C.
The proposed bus parking lot will be located on the north side of the school building,
between the building and U.S. Highway 264. This new lot will provide parking for 10

school buses and improve student access to the building from the bus area. This area will
be asphalt pavement with a grass island in the center of the lot.
Stormwater will sheet flow across the proposed bus parking lot and from there across
grass areas of the schoolyard. Once the runoff flows onto the grass adjacent to the lot, it
will flow via grass swales and into existing yard inlets. The minimum distance any
stormwater must travel over grass before entering one of the two existing yard inlets is
thirty-five feet.
In order to capture and remove suspended solids from the proposed faculty parking lot
and student drop-off / pick-up travel lane, a bioretention cell has been incorporated into
this plan. According to the NCDENR "Stormwater Best Management Practices" Manual,
Bioretention cells achieve a removal rate of 85% for total suspended solids. Bioretention
areas are intended to address the spatial constraints that can be found in intensely
developed urban areas where the drainage areas are highly impervious. Bioretention is a
water quality practice using plants and soils for the removal of pollutants from
stormwater runoff. All retention areas for this project were sized according to the
NCDENR "Stormwater Best Management Practices" Manual.
The boiretention cell receives stormwater from the proposed faculty parking lot and from
the student drop-off / pick-up travel lane. The total combined drainage area flowing into
the bioretention area is 71,900 square feet of parking and roadway area. Stormwater
runoff will sheet drain a I" inch runoff volume of 4,082 cubic feet into the bioretentiordg_--�
40 cell. The dimensions of the centralized cell measure 45 feet wide by 140 feet long with a,._q,
storage depth of nine inches. 6?,Qo 5�
In order to ensure adequate permeability of the soil, a sandy loam will be utilized as the
first foot of soil below the finished grade of the cell. This soil type will allow stormwater
runoff to seep into the earth, but will do so slowly enough to aid in the longevity of
vegetation in each cell.
During the design stage of this project, every option was exhausted in an effort to capture
stormwater runoff from proposed improvements as well as stormwater runoff from
existing improvements. An existing 30" RCP carrying stormwater from Hudnell Street
comes onto the Eastern Elementary School property and discharges into a grass swale on
the property. This runoff was deemed separate from the stormwater runoff that is to be
included in the treated stormwater and will pass through the proposed system without
routing through the bioretention area.
An existing 18" RCP also drains into the existing grass swale on the southwest side of the
Eastern Elementary property. This pipe carries stormwater from a courtyard interior to
the existing school building. Unfortunately, the invert of this pipe is too deep for the
stormwater to be routed into the bioretention area. This water will also pass through the
proposed system without routing through the bioretention cell.
All stormwater runoff from the proposed faculty parking lot and student drop-off / pick-
up travel lane will be routed to the bioretention cell, where the `first flush' will be treated.
In order to treat the stormwater runoff in the parking lot, a drop inlet will capture

stormwater from `low flow' storm events and divert it into the bioretention area. During
larger storm events, stormwater will continue to sheet flow across the drop inlet as it does
in smaller storm events. Any additional runoff not captured by the drop inlet will sheet
flow across the student travel lane and into the bioretention cell.
In order to make the lot economically feasible for the school to construct, the amount of
fill brought onsite had to be minimized. This, in turn, steepened the grade across the
parking lot. With an average parking lot grade of five percent, erosion due to stormwater
sheet flowing across the parking lot onto the adjacent grass would become a safety and
maintenance problem. Therefore, curb and gutter was utilized in this lot in order to
eliminate the potential for erosion. Rip rap energy dissipators will be installed at each
outlet entering the bioretention area.
There are two curb cuts that will allow stormwater runoff to flow from the student drop-
off/ pick-up travel lane into the bioretention area. Both of these curb cuts are guarded by
Rip Rap in an effort to dissipate the energy generated by the runoff and to help reduce
erosion.
The outlet structure for the bioretention area is a concrete block riser with four open sides
and a solid slab lid. The clear open area between the throat of the riser and the top slab is
set at four inches. The throat elevation of the outlet is set nine inches above the finished
grade on the floor of the bioretention area. This allows for a storage volume in the cell
ample to hold the 151 inch of runoff and allows any runoff in excess of the one inch storm
to discharge into an existing grass swale via concrete pipe.
Bioretention Area Maintenance
1, Vegetation shall be inspected twice annually. Remove/replace dead or diseased
plants. Also remove unwanted additional growth, such as weeds.
2. Remulch as necessary.
3. Once or twice annually, test the soil for pH and toxics. Lime should be added as
needed to increase pH. Soil should be replaced if toxics exist.
4. Remove trash and debris as necessary.
See Bioretention Area Maintenance Agreement for more detailed recommendations.
During construction of this project, the North Carolina Sedimentation Pollution Control
Act and the Rules and Regulations promulgated pursuant to the provisions of this act
must be adhered to. Attached are the specifications for Seeding and Mulching and
Erosion and Pollution Control, which are bound in the contract documents for this
. project. These specifications explicitly describe procedures to minimize offsite
sedimentation and erosion during the construction phase of this project.

RIVERS & ASSOCIATES, INC.
Engineers/Planners/Surveyors
107 E. 2nd Street P.O. Box 929
GREENVILLE, NORTH CAROLINA 27835
[phone] FAX [phone]
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Engineers/Planners/Surveyors SH EET NO. Of-
107 E. 2nd Street P.O. Box 929 CALCULATED BY . DUE
GREENVILLE, NORTH CAROLINA 27835
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RIVERS & ASSOCIATES, INC.
Engineers/Planners/Surveyors
107 E. 2nd Street P.O. Box 929
GREENVILLE, NORTH CAROLINA 27835
[phone] FAX [phone]
J013 JEWMN L'vT- ltapvpj
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RIVERS & ASSOCIATES, INC.
Engineers/Planners/Surveyors
107 E. 2nd Street P.O. Box 929
GREENVILLE, NORTH CAROLINA 27835
[phone] FAX [phone]
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O TARE 1
HAND AUGER RESULTS
Eastern Elementary School
Parking Lot Improvements
Washington, North Carolina
Hand Auger Depth
Unified Soil
Location (inches)
Soil Description
Classification
Bio Cell #1 0-6
Topsiol
6 - 12
Light Brown Fine Clayey Sand
SC
12 - 18
Medium Brown Fine Clayey Sand
SC
18 - 24
Dark Brown to Black Fine Silty Sand
SM
24 - 30
Dark Brown to Black Fine Silty Sand
SM
30 - 36
Medium Brown Fine Clayey Sand
SC
36 - 42
Gray Fine Sandy Clay
CL
*Water table at approximately 3' in depth

Rivers
&-Associates,
I I Inc.
TO: NC Department of Environment
and Natural Resources
Division of Water Quality
943 Washington Square Mall
Washington, North Carolina 27889
GENTLEMEN:
WE ARE SENDING YOU [X] Attached
( ] Shop Draivings [ ] Prints
J ] Copy of letter [ ] Change order
Engineers / Planners / Surveyors • Greenville, North Carolina
LETTER OF TRANSMI`l'TAL
Date 1J.b No.
March 4, 2003
ATTENTION:
Mr. William J. Moore
SUBJECT:
Beaufort County Schools - Eastern Elementary School
Stormwater Management Permit Application
Washington, North Carolina
[ ] Under separate cover via
[ ] Plans [ ] Samples
[ ] Other
Hand delivered the following items:
[ ] Specifications
COPIES
DATE
No.
DESCRIPTION
I J 2uU,i
2
2/26/03
Narrative and Calculations
2
2/26/03
W-2635
Construction Plans a�'J �n�,4
2
2/26/03
W-2635
Construction Specifications
2
Stormwater Management Permit Application
I
Stormwater Management Permit Application Fee
THESE ARE TRANSMITTED as checked below:
[XI For approval [ j Approved [ ] Resubmit copies for approval
[ J For your use [ ] Approved as noted [ ] Submit copies for distribution
[ ] As requested [ ] Disapproved [ ] Return corrected prints
] For review and comment [ ] Other
REMARKS:
Mr. Moore,
Attached for your review and approval is the subject Stormwater Management Permit Application
and submittal package.
Please do not hesitate to call if you have any questions or need any additional information.
With best regards,
COPIES ro: Phillip Boyd SIGNED: 7--
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lferulosures are aot as noted, kindly whfij us at once Bryr.agundus, E.I.
b fa gu n d us@riv e rsa nd a ssoc is tes. co m
107 East Second Street • Post Office Box 929 * Greenville, North Carolina 27835 " (252) 7524135 " FAX [phone]
8410 Falls of Neuse Road, Suite D " Raleigh, North Carolina 27615 " [phone] * FAX [phone]

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