20061223 Ver 1_More Info Received_20060831

Malpays & Associates
Engineering & Planning
1645 E. Arlington Blvd Suite D
Greenville, NC 27858
Phon+~. (252j 756-~178U
Fax: i252j 756-2098
August 30, 2006
North Carolina Department of Environment and Natural Resources
Division of Water Quality
401 Division
ATTN: Ms. Cyndi Karoly
2321 Crabtree Boulevard
Raleigh, NC 27604
RE: BROOKSTONE SUBDIVISION PHASE ONE
DWQ Project # 06-1223
Dear Ms. Karoly:
Please find enclosed the additional information requested in your letter dated August 14, 2006
regarding the above referenced project.
Items 1 i3< 2: Included are site plans showing the buffer zones and buffer impacts. Please note the only
impacts for phase one are the discharge pipe from pond 1 and the sanitary sewer main crossing. The
sewer main is a perpendicular crossing and exempt in accordance with NCAC 15A 028.0233 (6).
Item 3: A spreadsheet has been included. All areas are taken directly from the plan. The actual
impervious area is only 20% for the entire subdivision. Five copies of the corresponding PCN page
have also been incuded. I apologize for the confusion; the 24% is for the inflow to Pond 1 and was
used in the stormwater calculations.
Item 4: The worksheets and agreement an: here-in provided. The requested permitting at this time is to
allow discharge without diffuse flow due to topographic constraints.
Item 5: Copies of the corresponding USGS Quad Sheet and SCS soil survey map have been included.
If there are any questions regarding this information please contact me at [phone] or by e-mail
at [e-mail].
Sincerely,
~~
~~
Jamie Midgette, Engineering Intern
Malpass & Associates
AUG 3 1 2006

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YVEIIAND3 AND STORMWATEPi SRAMGH

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PROJECT: BROOKSTONE SUBDIVISION
ENGINEER: MALPASS & ASSOCIATES
DEVELOPER: KENNETH SMITH PROPERTIES, INC
DATE: Au ust 29, 2006
CALCULATING IMPERVIOUS COVER AT BUILD OUT CONDITIONS (AREA IN ACRES)
Pitt County subdivisions with lot sizes similar to Brookstone often have 2,000 sf houses and 1,300 sf of driveway and sidewalk.
In some cases the houses can be up to 2,500 sf, if they have garages and in these cases the driveways are often only 900 sf.
The average of these numbers was used in estimating the build-out conditions.
AREAS PHASE 1 PH ASE 2 TOTAL PER
DETAINED UNDETAINED DETAINED UNDETAINED TOTAL LOT SF)
BUILDING IMPERVIOUS 1.28 0.22 1.43 0.92 3.85 2266.89
TRANSPORTATION IMPERVIOUS OUTSIDE OF RNV 0.71 0.00 0.89 0.00 1.59 937.72
TRANSPORTATION IMPERVIOUS INSIDE OF RNV 1.90 0.00 2.44 0.00 4.34
ROAD 3.48

SIDEWALK
0.48 _ _-
DRIVEWAY 0.38 224.92
GRASS 12.00 5.73 13.19 8.13 39.05
SUBTOTAL 15.89 5.95 17.95 9.05 48.84
TOTAL IMPERVIOUS AREA 9.79
OF TOTAL AREA W/IMPERVIOUS COVER 20.04%

Zone* Impact
(s ware feet) Multiplier Required
Miti ation
1 450 3 (2 for Catawba)
2 300 1.5
Total
* Zone 1 extends out 30 feet perpendicular from the top of the near bank of channel; Zone 2 extends an
additiona120 feet from the edge of Zone 1.
3. If buffer mitigation is required, please discuss what type of mitigation is proposed (i.e.,
Donation of Property, Riparian Buffer Restoration /Enhancement, or Payment into the
Riparian Buffer Restoration Fund). Please attach all appropriate information as identified
within 15A NCAC 2B .0242 or .0244, or .0260. This is a temporary disturbance necessary to
install the outlet pipe The area will be restored after the installation is complete. Erosion
control measures will be in place to protect the adjacent buffer.
XI. Stormwater (required by DWQ)
Describe impervious acreage (existing and proposed) versus total acreage on the site. Discuss
stormwater controls proposed in order to protect surface waters and wetlands downstream from
the property. If percent impervious surface exceeds 20%, please provide calculations
demonstrating total proposed impervious level.
THE EXISTING IMPERVIOUS AREA IS «1% THE PROPOSED IMPERVIOUS AREA IS
20%. A STORMWATER CONTROL PLAN IS PROVIDED WITH THIS SUBMITTAL.
XII. Sewage Disposal (required by DWQ)
Clearly detail the ultimate treatment methods and disposition (non-discharge or discharge) of
wastewater generated from the proposed project, or available capacity of the subject facility.
ALL WASTEWATER WILL BE TREATED BY CONTENTNEA METROPOLITAN
SEWERAGE DISTRICT. NCDENR WWTF PERMIT NO. NC0032077. THE FAST TRACK
APPLICATION PROCESS IS CURRENTLY UNDERWAY.
XIII. Violations (required by DWQ)
Is this site in violation of DWQ Wetland Rules (15A NCAC 2H .0500) or any Buffer Rules?
Yes ^ No
Is this anafter-the-fact permit application? Yes ^ No
XIV. Cumulative Impacts (required by DWQ)
Will this project (based on past and reasonably anticipated future impacts) result in additional
development, which could impact nearby downstream water quality? Yes ® No ^
Page 12 of 13

Project No. DWQ (to be provided by DWQ)
DIVISION OF WATER QUALITY -401 WET DETENTION BASIN WORKSHEET
DWQ Stormwater Management Plan Review:
A complete stormwater 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 complete the following information):
Project Name : BROOKSTONE SUBDIVISION
Contact Person: JAMIE MIDGETTE Phone Number. ~2S217S6-1780
For projects with multiple basins, specify which basin this worksheet applies to: POND 1(WEST OF STREAM)
Basin Bottom Elevation 44.5 ft. (average elevation of the floor of the basin)
Permanent Pool Elevation 47.75 ft. (elevation of the orifice invert out)
Temporary Pool Elevation 49.0 ft. (elevation of the outlet structure invert in)
Permanent Pool Surface Area 9,860 sct. fl. (water surface area at permanent pool elevation)
Drainage Area, 15.89 ac. (on-site and off-site drainage to the basin)
Impervious Area 3.89 ac. (on-site and off-site drainage to the basin)
Permanent Pool Volume 28.500 cu. ft. (combined volume of main basin and forebay)
Temporary Pool Volume 14.810 cu. ft. (volume detained on top of the permanent pool)
Forebay Volume 5.100 cu. fl.
SA/DA used 1.42 (surface area to drainage area ratio)
Diameter of Orifice 1.50 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: 1 S 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.
/~~~ The basin side slopes are no steeper than 3:1.
~i~ 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 S 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.
~~ A minimum 30-foot vegetative filter is provided at the outlet.
!~i 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 O&M plan.
--~~ _A debris check is specified in the O&M plan to be performed after every storm event.
~/Lj A specific sediment clean-out benchmark is listed (elevation or depth) in O&M plan.
~''f A responsible party is designated in the O&M plan.
F RM SWG100 09/97 Page 1 of 1

o~- ~2,a3
Project No. DWQ (to be provided by DWQJ
DIVISION OF WATER QUALITY - 401 WET DETENTION BASIN WORKSHEET
DWQ Stormwater Management Plan Review:
A complete stormwater 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 complete the following information):
Project Name : BROOKSTONE SUBDIVISION
Contact Person: JAMIE MIDGETTE Phone Number: [phone]
For projects with multiple basins, specify which basin this worksheet applies to: POND 2 (EAST OF STREAM)
Basin Bottom Elevation
Permanent Pool Elevation
Temporary Pool Elevation
Permanent Pool Surface Area
Drainage Area
Impervious Area
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
SA/DA used
Diameter of Orifice
44.75 ft. (average elevation of the floor of the basin)
47.75 ft. (elevation of the orifice invert out)
49.0 ft. (elevation of the outlet structure invert in)
10,400 sq. ft. (water surface area at permanent pool elevation)
17.94 ac. (on-site and off-site drainage to the basin)
4.75 ac. (on-site and off-site drainage to the basin)
30,900 cu. ft. (combined volume of main basin and forebay)
18,605 cu. ft. (volume detained on top of the permanent pool)
5,500 cu. ft.
1.33 (surface azea to drainage azea ratio)
1.75 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 G (` n ~~ '•._.... ,.,,
The temporary pool controls runoff from the 1 inch storm event. ~ ~ a V
~~Z~_ The basin length to width ratio is greater than 3:1. f ~'f
The basin side slopes aze no steeper than 3:1. A U ~ ~
_A submerged and vegetated perimeter shelf at less than 6:1 is provided. L°,: 1 ZQ~6
Ve etation to the ermanent of elevation is s ecified. WETL,n~;°`
g P Po P t>~Nh , tVJ~rER ~UACtTY
.~f//~' An emergency drain is provided to drain the basin. ~~htDS1y,~nrRg~H
~i~i _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.
~/ A minimum 30-foot vegetative filter is provided at the outlet.
A site specific operation and maintenance (O&M) plan is provided.
/"I A vegetation management/mowing schedule is provided in the O&M plan.
~i"l Semi-annual inspections aze specified in the O&M plan.
/~~i 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.
.~'I A responsible party is designated in the O&M plan.
FO SWG100 09/97 Page 1 of 1

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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 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 5.75 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4.25 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 47.75
Sediment F~emoval EI.43.5 17
-----
-- -------i-- Sediment Removal Elevation 42.0 75%
-------------------------------------------- ------
Bottom E vation 42 5% • ~
FOREBAY MAIN POND U ~~~~ V
AU G 3 1 2006
DENR -WATER QUALITY
WETLANDS AND STQR!dWATER BRANCH
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.
Page 1 of 2

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.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Print name: ,~.~il/1l/,~% ~ ..~1 /,
Title
Addi
Phoi
Sign
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 presiden/to
I Q~ ~~ , a Notary Public for the State of~~~Gr~L ~-~iG- ,
County of T ~~ , do hereby certify that~~,~P~ ~i~~~
personally appeared before me this L_T/ ~- day of , Z~~ 6 ,and acknowledge the due
execution of the forgoing wet [wetland] detention basin maintenance requirements. Witness my hand and
official seal,
~~~~~`'PM K. M '~/iii
. qN .
_~ ~;~ NOTARy''o u,
~• ®ea a~
`s, pUBL1~ .''
A~ ~••. .~°'' V~
SEAL
My commission expires `~~Z>=/Zo//
Page 2 of 2

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