20061085 Ver 2_More Info Received_20061222

Project No. DWQ EXP 06-1085
Project Name: Elem School G
Bio-retention 1
SUBMITTED DESIGN: REQUIRED DESIGN:
elevations
Permanent Pool (ft) 661 0.5 ft. depth
Temporary Pool (ft) 661.5
areas
Permanent Pool SA (sq ft) 6775 6758 sq. ft.
Drainage Area (ac) 4.37 ac
Impervious Area (ac) 1.39 31.8 % impervious
Rational C 0.71
Size % 0.5 sand underdrain
volumes
Inlet Velocity 5.95 0 fps
Inlet Flow Depth 10 in
Depth to Ground Water 6 6 ft
Planting Soil Infiltration 0.52. 0.52 in/hr
In-Situ Soil Infiltration 0.6 0.00 in/hr

ok
ok
check veloci
ok
ok

Project Name: Elem School G
Project No. DWQ 061085
DA 3
SUBMITTED DESIGN:
elevations
Bottom of Basin (ft) 677
Permanent Pool (ft) 680
Temporary Pool (ft) 681.5
areas
Permanent Pool SA (sq ft) 9697
Drainage Area (ac) 5.32
Impervious Area (ac) 4.08
volumes
Permanent Pool (cu ft) .19450
Temporary Pool (cu ft) 19247.4
Forebay (cu ft) 3.857
other parameters
SA/DA 3.2
Orifice Diameter (in) 2
Design Rainfall (in) 1
Linear Interpolation of Correct SA/DA
Im ervious
Next Lowest 70
Project Impervious 76.7
Next Highest 80
REQUIRED DESIGN:
2.0 average depth status
3 ft. depth ok
1.5 ft. depth ok
5278 sq. ft. ok
7497 based on avg depth ok
76.7 % -
14295 cu. ft. ok
19.8 % ok
2.28 -
0.09 cfs drawdown -
2.5 day drawdown ok
3 ft. Permanent Pool Depth
SA/DA fron (Avg. Depth)
2..07........ 3.054282768 /.OS
2.28 x.34 1.31
2.38 3.324513767 1.43
3 ft 4

Project No. DWQ EXP 06-1085
Project Name: Elem School G
DA 4
SUBMITTED DESIGN:
elevations
Permanent Pool (ft) 672
Temporary Pool (ft) 672.5
areas
Permanent Pool SA (sq ft) 1950
Drainage Area (ac) 1.2
Impervious Area (ac) 0.45
Rational C 0.73
Size % 0.5
volumes
REQUIRED DESIGN:
0.5 ft. depth
1908 sq. ft.
ac
37.5 % impervious
ok
ok
sand underdrain
Inlet Velocity 1.93 0 fps check veloci
Inlet Flow Depth 6 in
Depth to Ground Water 6 6 ft
Planting Soil Infiltration 0.52 0.52 in/hr ok
In-Situ Soil Infiltration 0.6 0.00 in/hr ok

~ DAVIS-MARTIN-POWELL & ASSOCIATES, INC.
ENGINEERING LAND PLANNING SURVEYING
6415 Old Plank Road, High Point, NC 27265
- [phone] • Fax [phone] • www.dmp-inc.com
~ ~~~
~~_. ~,~~
o~~
}
2 ? ii) ~ December 22, 2006
~ o wgr~R ~h
sT°'~'~~ R RE: Elementary School G
DMP Job No. E3938
DWQ EXP No. 06-1085
Cynthia Van Der Wiele
NCDWQ Wetlands Unit
Express Review Program
2321 Crabtree Blvd
Suite 250
Raleigh, NC 27604
Dear Ms. Van Der Wiele:
Per your letter dated November 28, 2006, enclosed is one copy of the revised storm water plans
in accordance with your comments. Your comments are listed below with our response in
italics. As required by your letter, one (1) copy is going to you and two (2) copies are going to
Mr. Barry Love in the Mooresville Regional Office.
Storm water Management Plan
a. Operation and Maintenance Agreement: DWQ has not received a signed and
notarized operation and maintenance agreement for the bio-retention cells. You are
required to provide one (1) original and two (2) copies of this Agreement.
The OMAgreement has been revised to include operation and
maintenance instructions for the bio retention area along with the
O&M of the wet detention pond. The original and two (2) copies
are included with this subrreittal. Copies are enclosed in the
submittal to Mr. Love.
b. Bio-Retention Planting Plan: DWQ requires that the plant material be at least 2.5"
dbh for trees. Please explain why your plan specifies the use of smaller material.
The size classification was pulled off of another plan done for a
local municipality and I neglected to verify the size classifications
from the local municipality versus DWQ's required size. The plant
material has been changed to reflect a 2.5 "dbh as required by
DWQ.

c. Drainage Area 1/Bioretention:
i. The required surface area is significantly larger than the permanent pool
surface area you have proposed. Please redesign the Bioretention cell for
this drainage area in accordance with DWQ's storm water BMP design
guidance.
The Bioretention area has been redesigned in accordance with
the DWQ BMP design manual. The surface area required has
been calculated as explained on page 38 paragraph 2 and as
shown in Figure 12 page 39.
ii. DWQ generally recommends a ponding depth of 0.5 feet. Please explain
your temporary pool elevation.
The ponding depth is D.S'. The Bioretention worksheets that are
enclosed with this submittal have been changed to reflect this.
d. Drainage Area 3/Wet Pond:
i. Please explain the volumes for the permanent and temporary pool. You
have reduced the forebay volume to 1597.22; please explain why the
forebay volume has been reduced to 6.1
The permanent volume on the BMP worksheets is from the bottom
of the permanent pool to the top of the permanent pool. The
temporary pool is from the top of the permanent pool to the top of
the riser. The forebay volume has been increased to 19.8%.
ii. Please explain the SA/DA ratio used. The SA/DA ratio does not appear to
be based upon the five-foot permanent pool depth.
The permanent pool depth is 3 feet. The SA/DA is interpolated for
the 76.69 % impervious area with a Permanent pool depth of 3 '.
SA/DA values are found in Table 1.1 on page S of the BMP design
manual.
iii. DWQ has calculated a 5.2 day drawdown for the wet pond. Please
redesign to shorten this time.
A larger water quality hole has been added to the plans to reduce
the drawdown period below S days.
Drainage Area 4/Bioretention:
i. DWQ generally recommends a ponding depth of 0.5 feet. Please explain
your temporary pool elevation.
The ponding depth is 0.5 '. The Bioretention worksheets enclosed
with this submittal have been changed to reflect this.

ii. Please explain why the permanent pool surface area is significantly
smaller than design criteria would dictate for the drainage area/impervious
area.
The bioretention area has been redesigned in accordance with
the DWQ BMP design manual. The surface area required has
been calculated as explained on page 38 paragraph 2 and as
shown in Figure 12 page 39.
Thank you for your review. If you have any further questions or comments please do not
hesitate to give either me or Eddie MacEldowney a call. I look forward to hearing from you.
Sincerely,
Davis-Martin-Powell and Associates
Ja G ffey,
Cc: Barry Love (Mooresville RO)
Don Dixon (UCPS)
File

OPERATION AND MAINTENANCE AGREEMENT
ELEMENTARY SCHOOL "G"
REA ROAD
UNION COUNTY PUBLIC SCHOOLS
WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the
vegetated filter if one is provided.
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re-seed as necessary to maintain good vegetative cover, mow
vegetative cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet [wetland] detention basin or stream, etc.).
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 3.75 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 3.75 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 680
Sediment Removal EI. 676
75%
Sediment Removal Elevation 676.25
---------------------------------------
75%
Bottom E~vation _675:
FOREBAY
MAIN POND
Page 1 of 3

5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
7. All components of the wet detention basin system shall be maintained in good working order.
8. Level spreaders or other structures that provide diffuse flow shall be maintained every six months. All
accumulated sediment and debris shall be removed from the structure, and a level elevation shall be
maintained across the entire flow spreading structure. Any down gradient erosion must be repaired and/or
replanted as necessary.
BIO RETENTION AREAS OPERATION AND MAINTANCE AGREEMENT
The bio retention areas are defined as the plantings, mulched areas and out structure(s). Maintenance of the
bio retention areas shall be performed as indicated
1. Inspect monthly and repair as required any erosion.
2. Re mulch any bare areas noted during monthly inspection.
3. Remove all old mulch and re mulch every two years.
4. Inspect for insect infestation and diseased plants on a monthly basis. Treat infestation or disease as
required. Remove any diseased plants that are beyond treatment and replace during appropriate planting
season.
5. Inspect and replace tree support stakes as required.
6. Water plant material for during initial planting every 3 days for the first two months. Water as needed to
prevent the planting area from dying during drought conditions. Fertilize plantings during initial planting.
7. Remove any trash that has accumulated in the bio retention area. Identify source of trash and take steps
to prevent further trash from accumulating in the bio retention area.
8. Do not allow grass clippings to be dumped or wash into the bio retention area.
9. Inspect for debris around the inlet pipe. Remove debris as needed.
10. Inspect energy dissipator for displaced rip rap. Maintain dissipator as needed. If rip rap is continually
displaced into the bio retention area, replace rip rap with larger stone. This applies to dissipator(s) into the bio
retention areas and dissipator(s) from the overflow structure.
11. Observe draw down time of bio retention areas. If draw down exceeds 72 hours, remove and replace
mulch and top 4 inches of planting soil. Aerate planting soil prior to replacing mulch.
12. Prune bio retention planting annually.
13. Bio retention areas become acidic over time. Soil testing on an annual basis is recommended.
Application of limestone shall be done in accordance with the soil testing recommendations.
14. Soil testing should include tests for toxins and heavy metals. Plant life will become impaired due to the
accumulation of toxins and heavy metals. If toxins and heavy metals are allowed to accumulate to the point
where the bio retention planting materials are becoming ineffective, removal of all plants and planting soil may
be required.
Page 2 of 3

I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance
procedures listed above for the wet detention basin and the bio retention areas. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Print name: Donald S. Hughes, AIA
Title: Director Facilities Planning and Construction
Address: 116 North Main Street, Monroe, NC 28112
Phone:
Signatu
Date: ~ .~ ~ ., ,,,~,
Note: The legally responsible party should not be a homeowners association unless more than 50% of the
lots have been sold and a resident of the subdivision has been named the president.
I, ~r( (] ~ ~ ,1.~ ~~ , a Notary Public for the State of ~ Y ~ ~I~'
County of Z,l.~n~ (m , do h~~eby certify that .1t~~~nDon Hughes
personally appeared before me this !~ ~'` day of ~~` , _s~, and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
SEAL
My commission expires ~ d "~~ _~ ~ "
Page 3 of 3

OPERATION AND MAINTENANCE AGREEMENT
ELEMENTARY SCHOOL "G"
REA ROAD
UNION COUNTY PUBLIC SCHOOLS
WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the
vegetated filter if one is provided.
Maintenance activities shall be performed as follows:
1. After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re-seed as necessary to maintain good vegetative cover, mow
vegetative cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wet [wetland] detention basin or stream, etc.).
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 3.75 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 3.75 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
0 Permanent Pool Elevation 680
Sediment moval EI. 676.2 _ 75%
-------------- Sediment Removal Elevation 676.25 75%
-------------------------------------------- ------
Bottom E vation _675 5%
Bottom Elevation 67~_ '°
FOREBAY
MAIN POND
Page 1 of 3

5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
7. All components of the wet detention basin system shall be maintained in good working order.
8. Level spreaders or other structures that provide diffuse flow shall be maintained every six months. All
accumulated sediment and debris shall be removed from the structure, and a level elevation shall be
maintained across the entire flow spreading structure. Any down gradient erosion must be repaired and/or
replanted as necessary.
610 RETENTION AREAS OPERATION AND MAINTANCE AGREEMENT
The bio retention areas are defined as the plantings, mulched areas and out structure(s). Maintenance of the
bio retention areas shall be performed as indicated
1. Inspect monthly and repair as required any erosion.
2. Re mulch any bare areas noted during monthly inspection.
3. Remove all old mulch and re mulch every two years.
4. Inspect for insect infestation and diseased plants on a monthly basis. Treat infestation or disease as
required. Remove any diseased plants that are beyond treatment and replace during appropriate planting
season.
5. Inspect and replace tree support stakes as required.
6. Water plant material for during initial planting every 3 days for the first two months. Water as needed to
prevent the planting area from dying during drought conditions. Fertilize plantings during initial planting.
7. Remove any trash that has accumulated in the bio retention area. Identify source of trash and take steps
to prevent further trash from accumulating in the bio retention area.
8. Do not allow grass clippings to be dumped or wash into the bio retention area.
9. Inspect for debris around the inlet pipe. Remove debris as needed.
10. Inspect energy dissipator for displaced rip rap. Maintain dissipator as needed. If rip rap is continually
displaced into the bio retention area, replace rip rap with larger stone. This applies to dissipator(s) into the bio
retention areas and dissipator(s) from the overflow structure.
11. Observe draw down time of bio retention areas. If draw down exceeds 72 hours, remove and replace
mulch and top 4 inches of planting soil. Aerate planting soil prior to replacing mulch.
12. Prune bio retention planting annually.
13. Bio retention areas become acidic over time. Soil testing on an annual basis is recommended.
Application of limestone shall be done in accordance with the soil testing recommendations.
14. Soil testing should include tests for toxins and heavy metals. Plant life will become impaired due to the
accumulation of toxins and heavy metals. If toxins and heavy metals are allowed to accumulate to the point
where the bio retention planting materials are becoming ineffective, removal of all plants and planting soil may
be required.
Page 2 of 3

I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance
procedures listed above for the wet detention basin and the bio retention areas. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Print name: Donald S. Hughes, AIA
Title: Director Facilities Planning and Construction
Address: 116 North Main Street, Monroe, NC 28112
Phone
Signatu
Date: , ., ~, ,.,~,
Note: The legally responsible party should not be a homeowners association unless more than 50% of the
lots have been sold and a resident of the subdivision has been named the president.
1, ~rl (~ ~ 1 ,C~G~ ~~ , a Notary Public for the State of ~}~ Y~'1 ~~r/l~-J
County of ~~ I (m , do hereby certify that .~.,nDon Hughes
personally appeared before me this 3~V \ day of ~1NU.~'l , ~~Q, and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
SEAL
My commission expires ~ d "~ ~ _~
Page 3 of 3

DWQ Project No. ~ x p ~~' ~ ~ Qi S
DIVISION OF WATER QUALITY - BIORETENTION AREA WORKSHEET
I. PROJECT INFORMATION please complete the following information):
Project Name : ~l~meiz ~~ - ~- ~ i, ~~- _ arr
Contact Person: E ricl ~f ~G c ' $ ~~:. , ~~ ~, ~ Phone Number: j, ~, ~ ~) ~> ~ ~: - ~°? k ~..
For projects with multiple basins, specify which basin~this worksheet applies to:./~"~,~' f,'~ ~' ~, = ~ ~? J~ ~ _.'-
Permanent Pool Elevation
Temporary Pool Elevation
(~inf, ~!~ ft.
(elevation of the orifice invert out)
(elevation of the outlet structure invert in)
Bioretention Surface Area
Drainage Area
Impervious Area
Rational C Coefficient
Size
Inlet Velocity
Inlet flow depth
Depth to Ground Water
Planting Soil Infiltration Rate
to-Situ Soil Infiltration Rate
II. REQUIRED ITEMS CHECKLIST
~~ `) ~ ~ sq. ft.
`/, ? 7 ac.
/, 3q ac.
. "7 I
,rj
~-~ a `'~ fps
,~
.> ~ in
> ~ ft.
o.~a - ~. ~! in./hr.
(on-site and off-site drainage to the basin)
(on-site and off-site drainage to the basin)
(either 5% in wlsand under drain or 7% in w/o)
(the soil layer down to 4 feet)
%, L~ -- ~ ~ ~ in./hr. (the soil layer below 4 feet or below the sand bed)
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Aooficants Initials
~ n~.C-~ No vertical sand bed is proposed
.'r~~, The bioretention area is at least 40 feet by 15 feet.
Sheet flow is provided at inlet.
,1 a :' _.: Water table depth is greater than 6 feet.
`: ~y` <: Minimum of 6" ponding is provided.
Jr~' `~ The ponded area will draw down in less than 4 days.
v', r~' ~ Planting soil infiltration rate is greater than 0.52 in/hr.
.::~ t~:i., The in-situ soil infiltration rate is greater than 0.2 in/hr.
. `~r,~ `~ A planting plan with species and densities is provided.
,~' r: ~, Mulch layer is specified in plans.
~~'', Planting soil meets minimum soil specifications (NCDENR stormwater Best Management
Practices Manual, April 1999)
~~~ ~~: Plan details for the bioretention area provided.
r.~ ~~ Plan details for the inlet and outlet are provided.
'`-' F° An operation and maintenance agreement signed and notarized by the responsible party is provided.
Please note that underdrains beneath the planting soil are acceptable in the Piedmont and Mountains

rr jj~ ~ s
Client V6~#!~~ ~.~~+~;~-- d~: ~ ~d ~r,~z,,;~~~C,
Computed By ~~ ~`~~{
~: G
- Job No. ~~ ~Y.>`~ ; ~
Date A,~. ~ 1 ¢ ~ c? ~•-
dm
Project Description rk4.
Checked By
-
Calculations For 3 {
~" ~' `£ ~- ~ ~
Date
DAVIS-MARTIN-POWELL & ASSOCIATES, INC.
218 GATEWOOD AVE., SUITE 102, HIGH POINT, NC 27262 Page of

A-- ___ _ _
_.
_.__ _._

..,
m

..
~ ' ~_

,~ i

~, T'7 ~ ,~

_. _ .. ~_ .~. ~___ _ _ _ ~YV.4k 1:- ~-
.._ ~_ ~. ~ ~
~ _ v
_... ... _ _ , _.. __. _
____ 1. ~.~
-----:-

_
',
~ I r ~, I
_..,
m __ _ ~~ __

_.,,.u _.. _._ _ _;..._ .__. _ ._~~ ~~ ____

~ ___ ~
/~
,
_ _ _ ' _ ~ ._ _ _.
__.._,_ _..__. _~ _~_~_._ ~. ~
..._• _,r .~.__. __~_ _ ..._~.._ ~ ~_
~~4tiW°I°k- 4"~-.- ~f ~ 4a t 1.~ ~."i1is. ~;...t
'! {
h J!~ ~Wf F 4.';~i t~je. ~~('l ~f A'

~ }/
/
( y - i.
'
~
` 1 ci.~~' ~
n
_._.. _.,__._ ......,......ice.. ._ _
_,-.,., ,_.._.__,.:.. ..., ...,.. . .... ._ . ,. ........,. .. __....__. , __, ." ....,.:
.. ,,.
..
_ ; r
. ...
~.~.._..._.:

.~
' m.
$ G~ P, :-~ ter`
~"
~~ 1 ~
a ~
•-• ~
r
r~ ~ ~

a
_.
.
... _
,. .
,~, .
F (..~ _._ ___.. __ .... ......._ ,...
}"
_~.C,r,.
~ ~'_(..a..5. _ ~ . ,. _._ ._ ~ ._,., _ ,.__ .. _.. ~ _ ~,_~._ _ . _ ~_ _._ ~~. _ ~ _ _ , _

~-
,
:.~ _
r ___._

(Revised, Superseded, and Void Calculations Must Be Clearly Identified,
Initialed, and Dated by the Responsible Individual)

Project No. DWQ (to be provided by DWQ)
DIVISION OF WATER QUALITY - 401 WET DETENTION BASIN WORKSHEET
DWO Stormwater Management Plan Review:
A complete stonrnwater management plan submittal includes a wet detention basin worksheet for each basin,
design calculations, plans and .specifications showing all basin and outlet structure details, and a fully executed
operation and maintenance agreement. An incomplete submittal package will result in a request for additional
information and will substantially delay final review and approval of the project.
I. ~' PROJECT INFORMATION (please compto the following information):
Project Name : ~lP~n~d' ~r„~! ~~~ior~;`
Contact Person: E~ ~~ f?~ -;~~~t~~~~~ Phone Number: (,3101 ~~i~- `~~~`~~'%
For projects with multiple basins, specify wlri~h basin this worksheet applies to:7~PA~,~~,°9~~- z~«~t ~3
Basin Bottom Elevation ~o '~ ~ ft.
Permanent Pool Elevation ~n~~ ft.
Temporary Pool Elevation ~~'~- ~`j ~ ft.
(average elevation of the floor of the basin)
(elevation of the orifice invert out)
(elevation of the outlet structure invert in)
Permanent Pool Surface Area 9(O 9 ~ sq. ft. (water surface area at permanent pool elevation)
Drainage Area ..`~ . 4 ac. (on-site and off-site drainage to the basin)
Impervious Area ~/, 0 8 ac. (on-site and off-site drainage to the basin)
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
SA/DA used
Diameter of Orifice
f ~ ~`~ cu. ft.
%~ MS'S "y cu. ft.
,3, a
a,
(combined volume of main basin and forebay)
(volume detained on top of the permanent pool)
(surface area to drainage area ratio)
in. (draw down orifice diameter)
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices manual
(N.C. Department of Environment, Health and Natural Resources,~November 1995) and Administrative Code
Section: 15 A NCAC 2H .1008. Initial in the space provided to indicate the following design requirements have
been met and supporting documentation is attached. If a requirement has not been met, attach an explanation of
why.
Applicants Initials
The temporary pool controls runoff from the 1 inch storm event.
° „'"~ The basin length to width ratio is greater than 3:1.
_' e.-! _ The basin side slopes are no steeper than 3:1.
_' ;-~' " A submerged and vegetated perimeter shelf at less than 6:1 is provided.
° =--~ Vegetation to the permanent pool elevation is specified.
~~ ~~ An emergency drain is provided to drain the basin.
f ~ ' The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
~'' ~ The temporary pool draws down in 2 to 5 days.
~ The forebay volume is approximately equal to 20% of the total basin volume.
°~ ~-~ Sediment storage is provided in the permanent pool.
°° `> Access is provided for maintenance.
. r- ' A minimum 30-foot vegetative filter is provided at the outlet.
A site specific operation and maintenance (O&M) plan is provided.
' `~ A vegetation management/mowing schedule is provided in the O&M plan,
' ~ ~ ~~ Semi-annual inspections are specified in the 0&M plan.
E ~ _ A debris check is specified in the O&M plan to be performed after every storm event.
~ ' :-, A specific sediment clean-out benchmark is listed (elevation or depth) in O&M plan.
~~-! -: A responsible party is designated in the O&M plan.
FORM SWG100 09/97 Page 1 of 1

wetpond.xls
PERMANENT WET DETENTION POND DESIGN

PROJECT: ( School G INDEX NO:
CHECKED BY: etm
LOCATION: DATE:
REVISED: 12.22.06 JNG

SITE DATA ~
TOTAL SITE AREA = 5.32 acres WATERSHED =
PROPOSED BUILT UPON AREA = 4.08 acres CLASSIFICATION : WS -
FUTURE BUILT UPON AREA = 0.00 acres
TOTAL ON-SITE BUILT UPON AREA = 4.08 acres
PERCENT BUILT-UPON = 76.69% (GWA/WCA) _
ON-SITE DRAINAGE AREA TO POND = 5.32 acres MAX. OFF-SITE B.U.% _
OFF-SITE DRAINAGE AREA TO POND = 0.00 acres
TOTAL WATERSHED AREA TO POND = 5.32 acres
DISTURBED AREA = 5.32 acres
TEM P. SED. STOR. USED Y/N Y

DESIGN DATA
TEMPORARYSEDIMENT STORAGE 0.5 acre-inch per disturbed acre
PERMANENT SEDIMENT STORAGE 0.125 acre-in per total drainage area
PERMANENT WATER QUALITY
COMPOSITE B.U. % = 76.69 percent
DEPTH (minimum 3 feet) 3.0 feet
SA/DA (Figure 5.6-2) 3.2 percent
TEMPORARY WATER QUALITY 1.0 Inch rainfall to be controlled

PRINCIPAL SPILLWAY
TYPE X corrugated aluminum
reinforced concrete
DESIGN STORM 10 year
RAINFALL INTENSITY 5.32 inches per hour
RUNOFF COEFFICIENT 0.7

EMERGENCY SPILLWAY
TYPE X grass lined
rip-rap lined
DESIGN STORM 100 year
RAINFALL INTENSITY 8.15 inches per hour
RUNOFF COEFFICIENT 0.7

POND DATA
ELEV. @ BOT. OF POND =1 675 SURFACE AREA = 2518 SF
ELEV.@ BOT. OF PSS = 675 SURFACE AREA = 2518 SF
ELEV. @ BOT. OF PWQ = 677 SURFACE AREA = 4221 SF
ELEV. @ BOT. OF TWQ = 680 SURFACE AREA = 9697 SF
ELEV. @ TOP. OF TWQ = 681.5 I SURFACE AREA = 14968 SF
ELEV. @ EMER. SPILLWAY =1 683
ELEV. @ TOP OF DAM = 685 I j
INVERT OF BARREL =1 909 ':
Page 1

wetpond.xls
ELEV. @ BOT. OF POND= 675.00 SURFACE AREA = 2518 Square Feet I
ELEV. @ BOT. OF TWQ = 680.00 SURFACE AREA = 9697 Square Feet
ALLOW 75% OF BASIN VOLUME TO WQ ORIFICE _~ 22903 Cubic Feet
OKI
ELEV. @ BOT. OF PSS = 675.00 SURFACE AREA = 2518 Square Feet
ELEV. (~. BOT. OF PWQ = 677.00 SURFACE AREA = 4221 Square Feet_
VOLUME PROVIDED =
OKI
NORMAL POOL ELEVATION =I 680.001
~-r SURFACE AREA PROVIDED = 9697 Sauare Feet
I Rv= 0.740 in/in ~
VOLUME REQUIRED = 14295 Cubic Feet1
ELEV. @ BOT. OF TWQ =1680.00 ~ SURFACE AREA =9697 Square Feet
ELEV. (a7 TOP OF TWQ = 681.50 SURFACE AREA = 14968 Square Feet
VOLUME PROVIDED =
OK
Page 2

wetpond.xls
I i I
PRINCIPAL SPILLWAY

DESIGN STORM PEAK FLOW = 19.8 CFS
HEAD ABOVE TOP OF RISER = 1.50
ELEVATION AT TOP OF RISER = 681.50

BARREL: ELEV. OF BARREL INV. = 909
TRY BARREL DIA. = 24.00 in. dia. h = -227
ORIFICE EQUATION Q = #NUM! #NUM!

RISER: RISER(AREA) =1.5 TIMES BARREL(AREA)
TRY RISER DIA. = 36 in. dia.
WEIR EQUATION Q = 57.7 CFS OK

ORIFICE EQUATION Q= 41.7 CFS OK

ORIFICE CONTROLS

WATER QUALITY RELEAS E HOLE

ELEV. @ BOT. OF WATER QUALITY RELEASE HOLE = 680.00
MAXIMUM RELEASE RATE = 2 Days
MINIMUM RELEASE RATE = 5 Days
MAXIMUM HOLE SIZE = 0.028547078 2.29 in. dia.
MINIMUM HOLE SIZE = 0.011418831 1.45 in. dia.
I I I
EMERGENCY SPILLWAY

ELEV. @EMER. SPILLWAY = 683
DESIGN STORM PEAK FLOW = 30.4 CFS
FLOW THROUGH EMER. SPILLWAY = 10.5 CFS
HEAD ABOVE TOP OF RIS ER = 1
BOTTOM WIDTH = 3.51

FLOTATION OF RISER

ELEV. @ TOP OF RISER = 681.50
ELEV. @ BOT. OF PSS = 675.00
H = 6.50 ft
AREA OF RISER = 7.1 SF
VOLUME OF RISER = 45.9 Cubic Feet

AREA OF BARREL = 3.1 SF
EXPOSED LENGTH = 10.00 ft
VOLUME OF BARREL = 31.4 Cubic Feet

WEIGHT OF WATER DISPLACED = 4827.37 Ib
FACTOR OF SAFETY (10%) 5310.11 Ib

VOLUME OF CONCRETE ANCHOR = 35.4 Cubic Feet
Page 3

10 Year Storm
PROJECT: School G JOB NUMBER: E-3698
10-Year
O 25.15 D 24 AREA 3.14 EMERGENCY S PILLWAY
TP 17.0455 BARREL INVERT UP 675 ELEVATION 682.5
dT 4 Cw 3.33 BARREL INVERT OR LENGTH 25
Ks 2392.410083 L 160 DOWNSTREAM W.L. 674 C FACTOR 3
b 1.49 36 N FACTOR 0.027
N 1 STARTING LEVEL 680 Ke 1
Cd 0.59 SPILLWAY LEVEL 681.5
SPILLWAY AREA 7.07 SPILLWAY LENG TH 9.42
1
INFLOW STORAGE STAGE HEADWATER ORIFICE WEIR HYD. GRADE TOTAL EMERGENCY
__ __
TIME _
CFS CFS FT FLOW FLOW FLOW FLOW FLOW SPILLWAY

0.0 0.00 0 680.00 0.00 0.00 0.00 0.00 0.00 0
1.7 0.62 63 680.09 33.53 0.00 0.00 19.99 0.00 0
2.6 1.37 133 680.14 33.72 0.00 0.00 20.08 0.00 0
3.4 2.40 256 680.22 33.97 0.00 0.00 20.21 0.00 0
4.3 3.68 444 680.32 34.30 0.00 0.00 20.37 0.00 0
5.1 5.18 709 680.44 34.68 0.00 0.00 20.56 0.00 0
6.0 6.87 1060 680.58 35.11 0.00 0.00 20.78 0.00 0
6.8 8.69 1505 680.73 35.59 0.00 0.00 21.02 0.00 0
7.7 10.61 2047 680.90 36.11 0.00 0.00 21.28 0.00 0
8.5 12.58 2691 681.08 36.67 0.00 0.00 21.56 0.00 0
9.4 14.54 3434 681.28 37.24 0.00 0.00 21.85 0.00 0
10.2 16.46 4276 681.48 37.84 0.00 0.00 22.15 0.00 0
11.1 18.29 5211 681.69 38.45 14.54 2.57 22.46 2.57 0
11.9 19.97 6101 681.88 38.99 20.57 7.28 22.74 7.28 0
12.8 21.47 6827 682.03 39.40 24.26 11.94 22.95 11.94 0
13.6 22.75 7380 682.13 39.71 26.66 15.84 23.11 15.84 0
14.5 23.78 7786 682.21 39.93 28.25 18.86 23.22 18.86 0
15.3 24.54 8076 682.27 40.08 29.33 21.10 23.29 21.10 0
16.2 25.00 8276 682.31 40.18 30.04 22.66 23.35 22.66 0
17.0 25.15 8403 682.33 40.25 30.48 23.68 23.38 23.38 0
17.9 25.00 8486 682.34 40.29 30.76 24.34 23.40 23.40 0
18.8 24.54 8544 682.36 40.32 30.96 24.81 23.42 23.42 0
19.6 23.78 8563 682.36 40.33 31.02 24.96 23.42 23.42 0
20.5 22.75 8528 682.35 40.31 30.90 24.68 23.41 23.41 0
21.3 21.47 8429 682.33 40.26 30.57 23.88 23.39 23.39 0
22.2 20.14 8263 682.30 40.18 29.99 22.56 23.34 22.56 0
23.0 18.88 8074 682.27 40.08 29.32 21.08 23.29 21.08 0
23.9 17.69 7901 682.23 39.99 28.69 19.74 23.25 19.74 0
24.7 16.57 7739 682.20 39.90 28.08 18.51 23.20 18.51 0
25.6 15.53 7587 682.17 39.82 27.49 17.36 23.16 17.36 0
26.4 14.55 7443 682.15 39.74 26.91 16.30 23.12 16.30 0
27.3 13.64 7307 682.12 39.67 26.36 15.31 23.08 15.31 0
28.1 12.78 7177 682.09 39.60 25.81 14.38 23.05 14.38 0
29.0 11.98 7054 682.07 39.53 25.28 13.51 23.01 13.51 0
29.8 11.22 6937 682.05 39.47 24.76 12.70 22.98 12.70 0
30.7 10.52 6826 682.02 39.40 24.25 11.93 22.95 11.93 0
31.5 9.85 6720 682.00 39.34 23.76 11.21 22.92 11.21 0
Page 1

10 Year Storm

___ INTENSITY 5.91 SCS CURVE NO. 81

C" FACTOR
0.8 Weighted C -See
Below
PRECIP DEPTH
3.64
_____ DRAINAGE AREA 5.32 Tp 17.04554444
O 25.15296

__ S Z
CONTOUR CONTOUR INCR ACCUM
_ AREA VOLUME VOLUME STAGE In S In Z Zest
___ 675 2518.13 0 0 0
676 3331.86 2924.995 2924.995 1 7.9810 0.0000 2.0771
677 4220.89 3776.375 6701.37 2 8.8101 0.6931 2.1759
_ _ 678 5182.1 4701.495 11402.865 3 9.3416 1.0986 2.86_
679 7309.38 6245.74 17648.605 4 9.7784 1.3863 3.84
680 9696.7 8503 26152 5 10.1717 1.6094 5.00

Ks 2392.410083
------- - b 1.49

Area "C" C`A
1.24 0.5 0.62
4.08 0.95 3.876

5.32 4.496

__ Weighted C 0.8

Page 2

100 year Storm
PROJECT: School G JOB NUMBER: E~698
100-Year
O 34.69 D 24 AREA 3.14 EMERGENCY S PILLWAY
TP 22.0540 BARREL INVERT UP 675 ELEVATION 682.5
dT 4 Cw 3.33 BARREL INVERT O R LENGTH 25
Ks 2392.41008 L 160 DOWNSTREAM W. L. 674 C FACTOR 3
b 1.49 36 N FACTOR 0.027
N 1 STARTING LEVEL 680 Ke 1
Cd 0.59 SPILLWAY LEVE 681.5
SPILLWAY AREA 7.07 SPILLWAY LENG TH 9.42
1
__ INFLOW _ STORAGE STAGE HEADWATER ORIFICE WEIR HYD. GRADE TOTAL EMERGENCY
TIME CFS CFS FT FLOW FLOW FLOW FLOW FLOW SPILLWAY

0.0 0.00 0 680.00 0.00 0.00 0.00 0.00 0.00 0
2.2 0.85 112 680.13 33.67 0.00 0.00 20.05 0.00 0
3.3 1.89 237 680.21 33.94 0.00 0.00 20.19 0.00 0
4.4 3.31 457 680.33 34.32 0.00 0.00 20.38 0.00 0
5.5 5.08 793 680.48 34.79 0.00 0.00 20.62 0.00 0
6.6 7.15 1266 680.65 35.34 0.00 0.00 20.89 0.00 0
7.7 9.47 1892 680.85 35.97 0.00 0.00 21.21 0.00 0
8.8 11.98 2685 681.08 36.66 0.00 0.00 21.56 0.00 0
9.9 14.63 3653 681.33 37.40 0.00 0.00 21.93 0.00 0
11.0 17.34 4800 681.60 38.19 10.47 0.96 22.33 0.96 0
12.1 20.06 6064 681.87 38.97 20.36 7.06 22.73 7.06 0
13.2 22.70 7099 682.08 39.56 25.47 13.82 23.03 13.82 0
14.3 25.22 7853 682.23 39.96 28.51 19.37 23.23 19.37 0
15.4 27.54 8393 682.33 40.24 30.44 23.60 23.38 23.38 0
16.5 29.61 8805 682.40 40.45 31.82 26.93 23.48 23.48 0
17.6 31.37 9327 682.50 40.71 33.45 31.29 23.62 23.62 0
18.7 32.80 9934 682.61 41.00 35.22 36.52 23.77 23.81 0
19.8 33.84 10598 682.72 41.31 37.01 42.40 23.93 24.34 0
21.0 34.47 11268 682.84 41.62 38.71 48.51 24.08 25.52 1
22.1 34.69 11874 682.94 41.89 40.18 54.16 24.22 27.40 3
23.2 34.47 12343 683.02 42.09 41.22 58.59 24.33 29.50 5
24.3 33.84 12630 683.06 42.22 41.86 61.34 24.39 31.11 7
25.4 32.80 12741 683.08 42.27 42.10 62.41 24.41 31.80 7
26.5 31.37 12713 683.08 42.25 42.04 62.14 24.41 31.62 7
27.6 29.64 12582 683.06 42.20 41.75 60.88 24.38 30.82 6
28.7 27.78 12381 683.02 42.11 41.31 58.95 24.33 29.70 5
29.8 26.03 12138 682.98 42.01 40.76 56.65 24.28 28.50 4
30.9 24.39 11866 682.94 41.89 40.14 54.08 24.22 27.37 3
32.0 22.86 11568 682.89 41.75 39.44 51.29 24.15 26.34 2
33.1 21.42 11242 682.83 41.61 38.65 48.27 24.08 25.46 1
34.2 20.07 10885 682.77 41.45 37.75 45.01 23.99 24.75 1
35.3 18.81 10492 682.70 41.27 36.74 41.46 23.90 24.22 0
36.4 17.62 10056 682.63 41.06 35.55 37.58 23.80 23.88 0
37.5 16.51 9569 682.54 40.83 34.17 33.35 23.68 23.68 0
38.6 15.47 9026 682.44 40.56 32.52 28.76 23.54 23.54 0
39.7 14.50 8428 682.33 40.26 30.56 23.87 23.39 23.39 0
40.8 13.59 7779 682.21 39.92 28.23 18.81 23.21 18.81 0
41.9 12.73 7377 682.13 39.71 26.64 15.82 23.10 15.82 0
43.0 11.93 7120 682.08 39.57 25.56 13.97 23.03 13.97 0
44.1 11.18 6935 682.05 39.47 24.75 12.68 22.98 12.68 0
45.2 10.48 6790 682.02 39.38 24.08 11.68 22.94 11.68 0
46.3 9.82 6666 681.99 39.31 23.50 10.86 22.90 10.86 0
47.4 9.20 6557 681.97 39.25 22.97 10.13 22.87 10.13 0
48.5 8.62 6457 681.95 39.20 22.47 9.49 22.84 9.49 0
49.6 8.08 6363 681.93 39.14 21.99 8.89 22.82 8.89 0
50.7 7.57 6276 681.91 39.09 21.53 8.34 22.79 8.34 0
51.8 7.09 6193 681.90 39.04 21.08 7.84 22.77 7.84 0
52.9 6.65 6115 681.88 39.00 20.65 7.36 22.74 7.36 0
Page 1

100 year Storm

--~-~---~-~----- INTENSITY
--- 8.15
- SCS CURVE NO. 81

_____
C" FACTOR
0.8 Weighted C -See
Below
PRECIP DEPTH
5.3
DRAINAGE AR EA 5.32 T 22.0539732
O 34.6864

S Z
_
CONTOUR CONTOUR INCR ACCUM
AREA VOLUME VOLUME STAGE In S In Z Zest
________
675 _
2518.13 0 0 0
__
676 3331.86 2924.995 2924.995 1 7.9810 0.0000 2.0771
677 4220.89 3776.375 6701.37 2 8.8101 0.8931 2.1759
678 5182.1 4701.495 11402.865 3 9.3416 1.0986 2.86
679 7309.38 6245.74 17648.605 4 9.7784 1.3863 3.84
680 9696.7 8503 26152 5 10.1717 1.6094 5.00

Ks 2392.410083
b 1.49

Area "C" C'A
1.24 0.5 0.62
4.08 0.95 3.876

5.32 4.496

____ Weighted C 0.8

Page 2

Wet Detention Pond
Volume Worksheet

Sediment Forebay

EI Area Av. Area Volume Sum Volume

675 864.09
1042.75 1042.75
676 1221.41 1042.75
1608.585 2815.024
677.75 1995.76 3857.774

Overall Volume

EI Area Av. Area Volume Sum Volume

675 2518.13
2924.995 2924.995
676 3331.86 2924.995
3776.375 3776.375
677 4220.89 6701.37
4701.495 4701.495
678 5182.1 11402.87
6245.74 6245.74
679 7309.38 17648.61
8503.04 8503.04
680 9696.7 26151.65
11953.05 11953.05
681 14209.4 38104.7
14947.63 14947.63
682 15685.86 53052.33
16452.37 16452.37
683 17218.88 69504.7
17218.88 ~

DWQ Project No
DIVISION OF WATER QUALITY - BIORETENTION AREA WORKSHEET
I. PROJECT INFORMATION (please complete the following information):
Project Name : ~.,~F'r, ' `~ A ~.
Contact Person: ~ , ~ ~ F, ~ - ~ ~ r; Phone Number: (? ~~ 1 ~t~t: - ~`~'a: ~`
For projects with multiple basins, specify which basin this worksheet applies to: =r~ J;u rlA~~ ~ :'•'',~'',rs` ~` ~-

Permanent Pool Elevation `'~. ~~
~ ~
ft.
(elevation of the orifice invert out)
Temporary Pool Elevation ~ ~~ ~ ~° ft. (elevation of the outlet structure invert in)
Bioretention Surface Area r ~~ ~ sq. ft,
Drainage Area <-', ~' ;~ ac. (on-site and off-site drainage to the basin)
Impervious Area `_ ~ `~'~ ac. (on-site and off-site drainage to the basin)
Rational C Coefficient ~• `~. ~,
Size % ~" % (either 5% in w/sand under drain or 7% in w/o)
Inlet Velocity ~ ~--" fps
Inlet flow depth ~ in
Depth to Ground Water t,<; ft.
Planting Soil Infiltration Rate r^.sn - <.,•~, t~.' in./hr. (the soil layer down to 4 feet)
In-Situ Soil Infiltration Rate ;~, ~, - ~ • ~ in./hr. (the soil layer below 4 feet or below the sand bed)
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Applicants Initials
_I f~~a No vertical sand bed is proposed
J t~~ The bioretention area is at least 40 feet by 15 feet.
-- = ~-- Sheet flow is provided at inlet.
__' r> ~~- Water table depth is greater than 6 feet.
' r~.' ~ Minimum of 6" ponding is provided.
r::? r` The ponded area will draw down in less than 4 days.
1~..`': Planting soil infiltration rate is greater than 0.52 inlhr.
t«~ ° The in-situ soil infiltration rate is greater than 0.2 in/hr.
,`~ i~ ~~~ A planting plan with species and densities is provided.
4 f_t ~:~ Mulch layer is specified in plans.
ra f, Planting soil meets minimum soil specifications (NCDENR stormwater Best Management
Practices Manual, April 1999)
. `. ~-.`~'~, Plan details for the bioretention area provided.
`~ -~~ ~ Plan details for the inlet and outlet are provided.
. p=~ P, An operation and maintenance agreement signed and notarized by the responsible party is provided.
Please note that underdrains beneath the planting soil are acceptable in the Piedmont and Mountains

k
Client ~~ ' ''~~ ~'~'~ `'^ ~ ` Crt,d,~``" Computed By
dm Job No. +~ E 4"~ Date
- Project Description Checked By
Calculations For ti ~1 a ~` ~ ~ i Date
DAVIS-MARTIN-POWELL & ASSOCIATES, INC.
218 GATEWOOD AVE., SUITE 102, HIGH POINT, NC 27262 Page of
~ _ _L
_; ~ ~
_ __ . ._
-~,..~_ ~ M..; f~_ ~ . - _ ~
__.... .,
r ~.._ F -c -r-~~.

., _.._.__ .~_ . _ _._ __ .._ _ ___ ..,, U ._ , ~ ~_. _ .m _ _

_. ' __

. _ ~ _

__
Ot t~~
_ _..,,~~._ _~ ~_.~_

_.~ . ~3 _ . ;_. ,__.. .._.,._ w
~,r ~ ~,

~,

f:-,
F ~ ~
_._ . , ,,

_ - _ _
m,-~.._ < '`~
_
_.__ _., ..
.__....... _ _ s
.. _ _

(Revised, Superseded, and Void Calculations Must Be Clearly Identified,
Initialed, and Dated by the Responsible Individual)

The following explanation for not meeting all the requirements under Item II of the Bio-
Retention Worksheets and 401 Wet Detention Basin Worksheets for Elementary School
G.
Drainage Basin #1
Sheet flow is not provided into the bio retention area. The storm drainage system
discharges into the bio retention area. An adequately sized energy dissipator is located at
the discharge point.
Drainage Basin #4
Sheet flow is not provided into the bio retention area. The storm drainage system
discharges into the bio retention area. An adequately sized energy dissipator is located at
the discharge point.