20041808 Ver 3_Stormwater Info_20090831

OFFICE USE ONLY
Date Received Fee Paid Permit Number(s)
off. 18x8 U3
State of North Carolina
Department of Environment and Natural Resources f;:4
Division of Water Quality 401/Wetlands Unit
EXPRESS REVI EW PROGRAM STORMWATER MANAGEMENT APPLICATION FORM AU8 3 1 2009 (j
This form may be photocopied for use as an original
1METLANDS AND STORMW?BRANCH
1. GENERAL INFORMATION
1. APPLICANT'S NAME (specify the name of the corporation, individual, etc. who owns the project):
Stanly County Airport Authority
2. OWNER/SIGNING OFFICIAL'S NAME AND TITLE (person legally responsible for facility and
compliance): David Griffin, Airport Manager
3. OWNER MAILING ADDRESS (for person listed in item 2 above):
38512 Aviation Drive
New London, NC 28127
4. OWNER ADDITIONAL CONTACT INFORMATION:
Phone: [phone] Fax: [phone] Email: [e-mail]
5. PROJECT NAME (subdivision, facility, or establishment name - should be consistent with project name
on plans, specifications, letters, inspection and maintenance agreements, etc.):
Stanly County Airport Terminal
6. PROJECT LOCATION:
Street Address: 38512 Aviation Drive
City: New London County: Stanly State: NC Zip Code: 28127
Latitude: 35 24'39.99" N Longitude: 80 08'49.21 " W
7. DIRECTIONS TO PROJECT SITE (from nearest major intersection):
At the intersection of NC 49/US 52. Head southeast on W Church St/US-52 toward Bradford St for 6.5 miles.
Turn left at NC-1524/Prospect Church Rd. Contimue to follow NC-1524 for 2.4 miles. Continue on Airport
Road/NC 1549 for 0.7 miles. Aviation Drive on the Left.
8. CONTACT PERSON (who can answer stormwater-related questions about the project):
Name: Chad Vernon Company: Talbert & Bright
Phone: [phone] Fax: [phone] Email: [e-mail]
1/2009 Version 1.1 Page 1 of5
II. PERMIT INFORMATION
1. THE PROJECT IS (che ck one): ?X NEW ? A RENEWAL ? A MODIFICATION
2. OTHER JURISDICTIONS:
Which local government(s) has jurisdiction over the project (e.g. Town of Cary or Johnston County)?:
Stanly County
3. STORMWATER MANAGEMENT PROGRAM
Check all of the state-approved stormwater management programs (implemented by either the State or
local government) that apply to your project:
? Phase II Post Construction ? Water Supply Watershed ? Neuse or Tar-Pamlico NSW
? Randleman WSWS ? USMP ? Coastal Counties ? HQW ? ORW
4. PERMIT HISTORY (renewal or modification requests must complete this item):
Existing DWQ Permit Number: Date Issued:
5. PROJECT TYPE (check one): ?X Low Density* ? High Density*
* Low Density projects shall be under 24% Impervious with only vegetated stormwater conveyances. A
curb and gutter or pipe system for stormwater conveyance shall result in reclassification of project as
High Density even if below 24%, except when pipes are used for road or driveway crossing purposes.
6. ADDITIONAL PROJECT REQUIREMENTS (check all that apply):
? CAMA Major ?X Sedimentation/Erosion Control ? NPDES Stormwater
X? 404/401 Permit ? Non-404 Jurisdictional Permit ? Other:
Note: Information on required state permits can be obtained by contacting the Customer Service Center at
1-877-623-6748
III. PROJECT INFORMATION
1. STORM WATER TREATMENT METHODS (Describe briefly how stormwater will be treated):
The proposed impervious area (4.1ac) (T-Hangar Site and New Airport Terminal Site), will discharge with 0.6ac of
treatment, and the existing drainage area containing impervious area (4.5ac) (Aircraft Parking Apron) will be treated
using a single bioretention. A target of 85% TSS removal will be achieved. Both of these drainage areas combine just
downstream of the proposed BMP, on airport property.
Important Note: attach a detailed narrative (one to two pages) describing stormwater management for the
project.
2. RIVER BASIN/STREAM INFORMATION
a. Stormwater runoff from this project drains to which River Basin?: Yadkin-Pee Dee
b. Nearest narned stream: UT to Little Mountain Creek
c. Water quality classification of nearest named stream: WS-IV
1/2009 Version 1.1 Page 2 of 5
3. TOTAL PROJECT AREA: 1 14 (acres)
4. PROJECT BUILT UPON AREA: I 16%
5. DRAINAGE AREAS (How many drainage areas does the project have?): I
Complete the following information for each drainage area. If there are more than two drainage areas in the
project, attach an additional sheet with the information for each area provided in the same format as below.
Basin Information Drainage Area I I?rairtac a Area 2
Receiving Stream Name UT to Little Mountain Creek
Receiving Stream Class WS-IV
Drainage Area 109.8 AC
Existing Impervious* Area 16.7 AC
Proposed Impervious*Area 2.3 AC
% Impervious* Area (total) 17.3 %
Impervious* Surface Area Determination (Breakdown)
Impervious* Surface Area Drainage Area 1 Drainage Area 2
On-site Buildings 7344 SF
On-site Streets 27,576 SF
On-site Parking 43,618 SF
On-site Sidewalks 1,668 SF
Other on-site 18,550 SF
Off-site 16.7 AC
Total: 19 AC Total:
* Impervious area is defined as the built upon area including, but not limited to, buildings, roads, parking
areas, sidewalks, gravel areas, etc.
EXPLAIN HOW THE OFF-SITE IMPERVIOUS AREA WAS DERIVED:
USING THE SURVEYS OF THE AIRPORTS PROPERTY, NCDOT CONTOURS AND THE COUNTIES GIS
WEBSITE.
IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
Deed restrictions and protective covenants are required to be recorded for all subdivisions, outparcels and
future development draining to the proposed stormwater management devices prior to the sale of any lot. If
applicable, please complete and submit a copy of the deed restrictions and protective covenants along with
your application.
1/2009 Version 1.1 Page 3 of 5
V. SUPPLEMENT FORMS
1. The applicable stormwater management supplement form(s) listed below must be submitted for each
BMP specified for this project. The most current form(s) located on the 401/wetlands unit website at
http://h2o.enr.state.nc.us/su/bmp forms.htm must be used. Please include both the Design Summary and
the Required Items Checklist along with all required items and supporting design calculations.
(Check the supplement forms that will be required for your project):
?X Bioretention Supplement ?X Level Spreader/Filter Strip/Restored Buffer
? Dry Detention Supplement Supplement
? Sand Filter Supplement
? Grassed Swale Supplement
? Infiltration Basin Supplement ? Stormwater Wetland Supplement
? Infiltration Trench Supplement
? Wet Detention Supplement
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 DWQ Central Office.
1. Please indicate that you have provided the following required information by initialing in the space
provided next to each item.
Initials
• Original and two copies of the Express Review Stormwater Management Application SCA
• Signed and Notarized Inspection and Maintenance Agreement SCA
• Three copies of the applicable Supplement Form(s) for each BMP TBI
• Application processing fee (payable to DWQ) SCA
• Detailed narrative description of stormwater treat ment/management TBI
• Three copies of plans and specifications, including: TBI
?X Development/Project name
?X Engineer and firm
?X Legend
?X North arrow
X? Scale
?X Revision number & date
X? Mean high water line
?X Dimensioned property/project boundary
?X Location map with named streets or NCSR numbers
?X Original contours, proposed contours, spot elevations, finished floor elevations
X? Details of roads, drainage features, collection systems, and stormwater control measures
?X Wetlands and streams delineated, or a note on plans that none exist
X? Existing drainage (including off-site), drainage easements, pipe sizes, runoff calculations
? Drainage areas delineated
?X Vegetated buffers (where required)
1/2009 Version 1.1 Page 4 of 5
v
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.
2. MAILING ADDRESS:
4944 Parkway Plaza Blvd.
Suite 350
Charlotte, NC 28217
Phone: [phone] Fax: [phone]
VIII. APPLICANT'S CERTIFICATION
1, (print or type name ofperson listed in General Information, item 2)
David Griffin , certify that the information included on this application form is, to
1. DESIGNATED AGENT (individual or firm): Chad Vernon, Talbert & Bright, Inc.
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 (if applicable) will be recorded, and that the
proposed project complies with the requirements of 15A NCAC 2H .1000.
S
Date: Z
1/2009 Version 1.1 Page 5 of 5
E4c,p 04 -1908 v3
Stanly County Airport Authority
STORM WATER MANAGEMENT PLAN
Operation & Maintenance Plan
for
Stanly County Airport Terminal Project
Prepared by Talbert Bright Inc.
In association with HDR Engineering
Revised August 21, 2009
llftgflygy
AUG 3 12009
bMETLANDSV
ST?oRMWATER BRANCH
The following Operation & Maintenance Plan (OMP) has been prepared in compliance with
NCDENR DWQ 401 permitting requirements for the construction and operation of the project
entitled, New Terminal Building located at Stanly County Airport (SCA), New London, North
Carolina. The OMP describes SCA maintenance responsibilities for the monitoring, cleaning, and
necessary maintenance of the following Best Management Practices (BMPs) for these new
facilities:
1 . Filter Strips
2. Bioretention Basin
f
OPERATION AND MAINTENANCE AGREEMENT
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
I acknowledge and agree by my signature below
performance of the six maintenance procedures listed
DWQ of any problems with the system or prior to
responsible party.
Print name: David Griffin
Title: Airport Manager
Address: 38512 Aviation Drive
New London, NC 28127
Phone
Signature
Date:
that I am responsible for the
in this OMP. I agree to notify
any changes to the system or
I, 0 56-&,f N " , a Notary Public for the State of North
Carolina, County of St y, do hereby certify that
/\ Av i`d M • Gr 1 personally appeared before me this X4?
day of , 200, and acknowledge the due execution of the forgoing
Operation & Maintenance requirements. Witness my hand and official seal,
SEAL
My commission expires o l 0
1.0 Filter Strip
1.1 Description
Filter strips are uniformly graded and densely vegetated sections of land; engineered
and designed to treat runoff from and remove pollutants through vegetative filtering
and infiltration. Any natural vegetated form, from grassy meadow to small forest, may
be adapted for use as a filter strip. However, the vegetation must have dense foliage and
thick root mat to be effective. Filter strips are designed to accept runoff from overland
sheet flow from upgradient development. The strips trap sediment and sediment-bound
pollutants. Because they "disconnect" impervious surfaces from storm sewers and lined
channels, filter strips reduce effective imperviousness and help reduce peak discharge
rates by increasing travel time and by increasing abstractions from the total flow. Filter
strips typically include some method of spreading the runoff as sheet flow.
1.2 Monitoring
During the first 1 or 2 years after construction, filter strips should be inspected for
proper distribution of flows and signs of erosion during and after major storm events.
After the first 1 or 2 years, the strip may be inspected annually or biannually. If evidence
of erosion exists, the eroded areas should be filled in and reseeded. The cause of the
erosion should then be determined and, if possible, eliminated.
1.3 Maintenance
With minimal maintenance, filter strips can be effective indefinitely. However, strips
that are not maintained properly may quickly become nonfunctional. Maintenance
involves routine activities such as mowing, trimming, and replanting when necessary.
Strips that are used for sediment removal may require periodic regrading and reseeding
of their upslope edge because deposited sediment can kill grass and change the
elevation of the edge such that the stormwater no longer flows through the strip in thin
sheets. Important operation and maintenance procedures:
¦ Immediately after the filter strip is established, any newly planted vegetation
will be watered twice weekly if needed until the plants become established
(commonly six weeks).
¦ Stable groundcover will be maintained in the drainage area to reduce the
sediment load to the vegetation.
¦ Two to three times a year, grass filter strips will be mowed and the clippings
harvested to promote the growth of thick vegetation with optimum pollutant
removal efficiency. Turf grass should not be cut shorter than 3 to 5 inches and
may be allowed to grow as tall as 12 inches depending on aesthetic requirements
(NIPC,1993).
¦ Once a year, the soil will be aerated if necessary.
¦ Once a year, soil pH will be tested and compare it to the recommended pH for
the specific vegetation. Lime will be added if necessary.
¦ Repair gullies and rills that form and regrade the filter strip to ensure that the
runoff flows evenly in a thin sheet over the filter strip.
¦ Reseed and regrade the filter strip to maintain a dense growth of vegetation,
especially if the strip has been used for sedirnent control.
¦ Keep the filter strip free of litter.
¦ Evaluate the runoff from adjacent areas to determine if it is providing enough
water and nutrients or if additional irrigation and fertilizer are needed.
After the filter strip is established, it will be inspected quarterly and within 24 hours
after every storm event greater than 1.0 inch (or 1.5 inches if in a Coastal County).
Records of operation and maintenance will be kept in a known set location and will be
available upon request. Inspection activities shall be performed as follows. Any
problems that are found shall be repaired immediately.
BMP element: Potential problems: How I will remediate the
problem:
The entire filter strip Trash/debris is present. Remove the trash/ debris.
system
The flow sputter device is Unclog the conveyance and
clogged. dispose of any sediment off-
The flow sputter device site.
(if applicable) The flow sputter device is Make any necessary repairs or
damaged. replace if damage is too large
for re air.
The swale is clogged with Remove the sediment and
sediment. dispose of it off-site.
There is erosion around the Regrade the soil to create a
end of the level spreader that berm that is higher than the
shows stormwater has level lip, and then plant a
The swale and the level bypassed it. ground cover and water until
lip it is established. Provide lime
and a one-time fertilizer
application.
Trees or shrubs have begun Remove them.
to grow on the swale or just
downslo of the level lip.
Areas of bare soil and/or Regrade the soil if necessary to
erosive gullies have formed. remove the gully, and then
reestablish proper erosion
control.
The bypass channel Turf reinforcement is Study the site to see if a larger
damaged or ripap is rolling bypass channel is needed
downhill. (enlarge if necessary). After
this, reestablish the erosion
control material.
Grass is too short or too long if Maintain grass at a height of
applicable). approximately three to six
The filter strip inches.
Areas of bare soil and/or Regrade the soil if necessary to
erosive Ilies have formed. remove the gully, and then
plant a ground cover and
water until it is established.
Provide lime and a one-time
fertilizer application.
Sediment is building up on the Remove the sediment and
filter strip. restabilize the soil with
vegetation if necessary.
Provide lime and a onetime
fertilizer application.
Plants are desiccated Provide additional irrigation
and fertilizer as needed.
Determine the source of the
problem: soils, hydrology,
Plants are dead, diseased or disease, etc. Remedy the
dying problem and replace plants.
Provide a one-time fertilizer
a lication.
Remove vegetation by hand if
Nuisance vegetation is possible. If pesticide is used,
choking out desirable species. do not allow it to get into the
receivin water.
Erosion or other signs of Contact the NC Division of
The receiving water damage have occurred at the Water Quality local Regional
outlet. Office, or the 401 Oversight
Unit at 919-733-1786.
1.4 Schedule
The scheduled activities will occur as follows:
Activities Frequency
Inspect filter strips and level spreaders For the first two years during and after major
storm events
After first two ears annually or biannually
Remove deposited sediment Annually, as needed
Repair gullies and rills that form As needed
Re grade the filter strip As needed
Reseed and re grade the filter strip As needed
Mow filter strips vegetated with asses Regularly to maintain height
Harvest clippings Two to three times per year
Remove debris As needed
Evaluate runoff from adjacent areas As needed
Perform periodic aeration of the soil As needed
Test the soil pH As needed
2.0 Bioretention Basins
2.1 Description
Bioretention Basins treat stormwater runoff on developments commonly located in
densely site constraints such as parking lot islands or within small pockets of land uses.
Surface runoff is directed into shallow, ground depressions. These depressions are
designed to integrate many of the pollutant removal methods that function in natural
ecosystems. During rainstorm events, runoff ponds above the mulch and soil in the
bioretention system then filters through the mulch and prepared soil mix. Typically, the
filtered runoff is collected in a perforated underdrain and diverted to the storm drain
system.
2.2 Monitoring
After the bioretention basin is established, an inspection will be conducted once a month
and within 24 hours after every storm event greater than 1.0 inches.
2.3 Maintenance
Like any landscape feature, bioretention areas must be pruned, mulched, and initially
watered and limed. Grassed bioretention cells are usually mowed. Because plants are an
important investment and essential to the aesthetic appeal of bioretention systems, they
need to be established as quickly as possible. The need for rapid establishment requires
bioretention cells to be limed, if indicated by a soil test. Additionally, plants may need to
be spot-fertilized to ensure growth and survival in soils. Watering the plants every 2 to 3
days for a couple of months helps ensure vegetation survival. The frequency of these
tasks varies seasonally, with more frequent maintenance required in summer than in
winter. Maintenance to bioretention basins include occasional removal of mulch and the
top layer of fill soil. Since clogging occurs frequently at the top of the soil column, the
bioretention basins rarely need to be completely excavated. Important operation and
maintenance procedures:
• Immediately after the bioretention cell is established, the plants will be watered
twice weekly if needed until the plants become established (commonly six
weeks).
• Snow, mulch or any other material will NEVER be piled on the surface of the
bioretention cell.
• Heavy equipment will NEVER be driven over the bioretention cell.
• Special care will be taken to prevent sediment from entering the bioretention cell.
• Once a year, a soil test of the soil media will be conducted.
• Watering should not be required after establishment (about 2 to 3 years).
However, watering may be required during prolonged dry periods after plants
are established.
• Inspect flow entrances, ponding area, and surface overflow areas periodically.
Replace soil, plant material, and/or mulch in areas where erosion has occurred.
If sediment is deposited in the bioretention facility, immediately determine the
dead?P problem. ?ten? may be necessary.
source, remove excess dd °emoval of correct
P Occasional pruning an
established-
Periodic weeding is necessary until groundc hes where heavy metal deposition is
Replace mulch annually in bioretention facile lots
roads likely (e.g., commercial/ industrial uses, nokingon ernrrep ace or aresidddmuential
h as
other settings where metal deposition is
needed to maintain a 2 to 4 inch depth at least once every two years.
• Soil mixes for bioretention facilities are design to maintain long-term fertility and
pollutant processing. Therefore, the capability tests should be conducted in 20
years for metal toxicity. If this is above the standard allowance then the soil
should be replaced.
After the bioretention basin is established, mat 10 inches. ecords of inspection
within 24 hours after every storm event greater ion and will
maintenance will be kept in a known setroblems that available ar upon
shall
Inspection activities shall be performed as follows. Any P
be repaired immediately.
BMP element:
The pretreatment area
The bioretention cell:
vegetation
Potential problems:
Flow is bypassing
pretreatment area and/or
gullies have formed.
Sediment has accumulated to
a depth greater than three
inches.
Erosion has occurred.
Weeds are present.
Best professional practices
show that pruning is needed
to maintain optimal plant
health.
Plants are dead, diseased or
dying.
How I will remediate the
Regrade if necessary to route
all flow to the pretreatment
area. Restabilize the area after
Search for the source of the
sediment and remedy the
problem if possible. Remove
the sediment and restabilize
the pretreatment area.
Provide additional erosion
protection such as reinforced
turf matting or riprap if
needed to prevent future
erosio=roblems.
Remob hanPrune according to best
professional practices.
Determine the source of the
problem: soils, hydrology,
disease, etc. Remedy the
problem and replace plants.
Provide a one-time fertilizer
application to establish the
ground cover if a soil test
indicates it is necessary.
Albemarle-Stanly County Airport
STORM WATER MANAGEMENT PLAN
Project Narrative
for
Stanly County Airport Terminal Project
Prepared by Talbert Bright Inc.
In association with HDR Engineering 1@@R0V[A,
August 21, 2009 A UU 3 1 2009
DENR - W=A Alll Y
IMET?ANpS AND SII<R 9 ".
Project Description
Albemarle-Stanly County Airport is proposing to construct a new terminal
building just south of the existing runway on airport property. The stormwater
management plan is to retrofit an existing detention basin with a bioretention cell
to meet the water quality requirements for the airport's new improvements.
Construction Phasing and Temporary Measures
Temporary Sediment and Erosion Control measures are proposed and are
illustrated on the plans. This project has obtained an approved NCDENR
sediment and erosion control permit STANL-2009-016.
Storm Water Management Facilities
Permanent drainage facilities have been proposed in accordance with the various
governing jurisdictions for this project. Storm water conveyance on the airport's
airfield has been designed in accordance with FAA criteria to pass the 10-year
design storm.
Permanent post-construction site runoff control has been planned to take
advantage of the site requirements for runway and taxiway operations per FAA
requirements, and to work within the limitations of the site layout. In addition,
FAA requirements prevent some of the more acceptable BMPs (i.e. wet ponds are
prohibited within 10,000 feet of an airfield). Given these requirements and site
characteristics, the proposed site runoff controls for storm water treatment
consist of the following:
¦ Filter Strips - Grass shoulders along the edge of pavements, graded at 3%
slope, will serve as a filter strip. The longitudinal slope of these pavements
supports runoff in a laminar flow. TSS removal for each 30 feet of filter
strip is projected at 25%, and N removal at 25%.
¦ Bioretention - The design will incorporate grass as the growing media for
TSS removal performance. This has a removal of 85 % for TSS. This
design has the ability to be installed in a compacted area along the edge of
an existing airfield ramp. A filter strip will lead the stormwater to the
bioretention basin.
Both of the proposed facilities are located on airport property. The Albemarle-
Stanly County Airport is a public facility and the storm water management
facilities will be maintained by County employees.
Supporting Calculations of Treatment Devices
This project shall follow the calculation procedure to be listed in the BMP
Manual for treatment processes. Supporting calculations are attached in
spreadsheet form to illustrate the use of the above BMP throughout the project.
Plans are attached to illustrate where each BMP is located to allow runoff from
the pavement to go through the bioretention treatment device prior to
discharging off-site.
Two drainage areas comprise the project area's stormwater runoff. A trade off of
drainage areas is proposed for treating the impervious areas. Due to site
limitations and the possibility of creating additional environmental impact, the
project proposes treating existing and part of the proposed impervious runoff in
lieu of treating the entire proposed impervious area. The proposed impervious
area (4.1ac) (T-Hangar Site and New Airport Terminal Site), will discharge with
0.6ac of treatment, and the existing drainage area containing impervious area
(4.5ac) (Aircraft Parking Apron) will be treated using a single bioretention. A
target of 85% TSS removal will be achieved. Both of these drainage areas
combine just downstream of the proposed BMP, on airport property.
To promote a lower impact to the water quality in the receiving streams, the
project design has incorporated roadways with grass lined shoulders, in lieu of a
curb/gutter edge. The proposed parking area runoff will discharge through
sheet-flow along the edge of pavement and into grassed shoulders, rather be
collected with curb/ gutter and drainage inlets.
Albemarle-Stanly County Airport
Terminal Project
HDR Engineering, INC
August 21, 2009
Bioretention Design Analysis for Stanly County Airport Terminal Project
An analysis was performed for the existing detention pond north of the new terminal
building, east of the airfield ramp for qualification as a water quality bioretention pond
(BDP). The bioretention supplement form has been completed. In addition are the
supporting calculations for the design, drawdown times, underdrain sizing and entrance
velocities. Also included is the soils report; provided by Geo Technologies.
Utilizing the eight-step process, the location was determined due to the drainage area and the
location of the existing impervious surfaces created by the existing ramp draining to the east,
and within the same watershed as the runoff from the proposed project. This targeted area is
the location of an existing detention pond. The volume of water to treat the first flush is
17,874cuft. With a ponding depth of one foot, the required surface area of the cell is
17,908sgft. Drawdown times are provided. The volume, surface area and permeability of
the soil (1.5 in/hr) were taken into account. Using a 4-inch underdrain pipe, the drawdown
time for the first one foot of soil is 8 hours and the second foot is 16 hours. It was
determined that the cell will have a complete drawdown time within the allowable 24 hrs. In
addition, the flow in the underdrains was checked and confirmed that the flow in the 4-inch
diameter pipes do not exceed the capacity of the underdrains supporting the use of a 4- inch
diameter pipe. Therefore, no backwater will occur. The 1-yr peak flows for this section of
runway were calculated. The velocity of the approaching filter strip was evaluated using
Manning's equation, assuming the filter strip will act as a wide channel. The incoming flow
from this area is designed with roughness of a dense cover of Fescue grass (Manning's "n" =
0.035). The longitudinal slope for section D is approximately 2.1% with a base width of
222-feet. The velocity calculated is 0.9fps.
Attachments to this design memo include velocity calculations and supporting data on
drawdown times.
HDR Engineering, Inc
Albemarle-Stanly County Airport
Terminal Project
Bioretention Swale Calculations for Albemarle-Stanly County Airport
HDR Engineering, Inc
August 21,2009
Drainage
Section Area (sqft) Drainage
Area (ac) Pervious
Area (sqft) Impervious
Area (sqft) Impervious
Area (ac)
360,094.00 8.27 141,774 218,320 5.0'
Ponding Depth 1 ft
Basin Dimension Summary
Section Width (ft) Length (ft)
A 74 242
Drainage Area A
Impervious portion of Drainage Area
Total Drainage Area
5.01 = 0.61
8.27
Rv= 0.05+0.91A = 0.60
Volume 3630*Rp*Rv*A = 17,874 cft
Width = 74 ft
Length = 242 ft
Surface Area of Bioretention Cell = 17,908 sqft
Albemarle-Stanly County Airport
Terminal Project
Bioretention Calculations for Drainage Area A
Drawdown Calculations
Total volume to be treated
Permeability of Soil (PoS)
Surface Area of Soil (SA)
Draw down time for ponded area
V to be treated
PoS * SA of Soil
17874
0.125 17908
Drawdown Time to 24 in below surface
1 ft of Ponding Depth into soil is
2 ft of soil is
Total Drawdown time
Underdrain Sizing
Q in Volume 17,874 cft
Time 24.0 hr
17,874 cft
1.5 in/hr
17,908 cft
8.0 hrs
8.0 hrs
16.0 hrs
24.0 hrs
V = 0.21 cfs
T
Using Orifice Equation
HDR Engineering, Inc
August 21,2009
CD 0.4
D 4 in
Area 0.09 sqft
Havg 1.5 ft
g 32.17 ft/s^2
Q out = Cd * A * SQRT (2gH) = 0.34 cfs
Using BMP manual the minimum diameter required is:
D = (16*Q*n /( S A 0.5)) ^3/8
n 0.011
S 0.005
D 0.78 in
Using a 4 in underdrain exceeds the flow into the underdrains by 0.14 cfs
NCDENR recommends two 4 in underdrains, the plan includes 4 underdrains spaced 50 feet apart.
Therefore, no backwater will occur.
Albemarle-Stanly County Airport
Terminal Project
HDR Engineering, Inc
August 21,2009
Velocity Calculations for Albemarle-Stanly County Airports Biosretention Entrance
Bioretention Design section Vertical Z therefore no slope
A Rectangular shape
L delta h i
ft ft ft/ft
770 16.00 0.021 Qd n = 24.36 cfs
esi
Manning's Equation g
Q v B Y z A n P R
Cfs fps ft ft sq ft Grass ft
20.83 0.8 242 0.102 0 24.7 0.035 484.20 0.05
24.34 0.9 242 0.112 0 27.1 0.035 484.20 0.06
45.03 1.1 242 0.162 0 39.2 0.035 484.20 0.08
70.50 1.4 242 0.212 0 51.3 0.035 484.20 0.11
100.33 1.6 242 0.262 0 63.4 0.035 484.20 0.13
Bioretention Entrance Flows
Top e om Steepest
Sub-Basin Elevation Elevation Drainage Drainage Impervious Impervious Min. Side Effective Cover
ID (ft) (ft) Length, Ft. Area, sgft Area, Ac. Area, sgft. Area, Ac. Slope Slope ft ft Crop 1 yr cfs 1 yr f/s
A 595 579 770 360,094 8.3 218,320 5.0 5 :1 0.021 Fescue 24.36 0.9
I = 4.86 in/hr
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Albemarle-Stanly County Airport
Terminal Project
Bioretention A
Alhenwile North Cmolini
Precipitation Data Chart From: http://hdsc.nws.noaa.gov/hdsc/pfds/
Precipitation Freauencv Estimates (inches)
HDR Engineering, Inc
August 21,2009

ARI'
(years)
5 min
10 min
15 min
30 min
60 min
120 min
3 hr
6 hr
12 hr
24 hr
48 hr
4 da
7 da
10 da
20 da
30 day
45 da
60 day
1 0.41 0.65 0.81 1.11 1.38 1.61 1.72 2.08 2.48 3.02 3.54 3.97 4.55 5.2 7.01 8.6 10.88 13.04
2 0.48 0.76 0.96 1.33 1.67 1.94 2.07 2.51 3 3.64 4.26 4.76 5.42 6.19 8.27 10.12 12.75 15.21
5 0.56 0.89 1.13 1.6 2.05 2.41 2.59 3.14 3.76 4.57 5.31 5.88 6.61 7.45 9.76 11.77 14.58 17.19
10 0.61 0.98 1.24 1.79 2.33 2.76 2.98 3.62 4.37 5.3 6.14 6.76 7.55 8.43 10.94 13.05 15.98 18.72
25 0.67 1.07 1.36 2.01 2.67 3.2 3.5 4.27 5.19 6.29 7.25 7.96 8.84 9.75 12.53 14.72 17.81 20.68
50 0.71 1.14 1.44 2.17 2.93 3.54 3.9 4.78 5.85 7.09 8.14 8.92 9.87 10.8 13.77 16.01 19.2 22.18
100 0.75 1.19 1.5 2.3 3.17 3.87 4.3 5.29 6.53 7.9 9.05 9.9 10.93 11.85 15.03 17.3 20.56 23.61
200 0.78 1.24 1.56 2.43 3.41 4.18 4.71 5.82 7.24 8.74 9.99 10.92 12.02 12.93 16.3 18.58 21.89 25
500 0.81 1.29 1.62 2.56 3.69 4.59 5.25 6.54 8.22 9.89 11.28 12.32 13.51 14.39 18.04 20.3 23.64 26.83
1000 0.84 1.32 1.65 2.68 3.91 4.9 5.67 7.09 9 10.81 12.3 13.43 14.7 15.54 19.4 21.62 24.96 28.2
Finding The 10-yr, 24-hr
Read Chart:
Intensity, Peak 10-yr, 24-hr
d(in)/24hr
Time of Conc.: Tc=
=(L3/H).385/128
Hydraulic Length, L
Change in Elev., H
Intensity, Peak 10-yr
d(in)/t,(min)'60(min/hr)
Depth at Tc & 10-yr: d=
Intensity, Peak 1-yr
d(in)/t,(min)'60(min/hr)
Depth at T.& 1-yr: d=
Intensity, Peak 1-yr, 24-hr
d(in)/24hr
Depth at 24hr& 1-yr: d=
4.57 inches
0.19 in/hr
5.80 min (Calculate this value from the hydraulic length and the change in elevation along the hydraulic length)
770 ft Furthest distance water flows to BMP
16.00 ft Over hydraulic length
5.80 in/hr
Si in
0.45 in/hr
in
0.13 in/hr Use time of concentration to determine the "1-yr" storm, but not the "1-yr, 24-hr" storm. Note that the "1-yr, 24-hr"
3.02 in value discussed here is the regulated storm.
Form SW401-Bioretention-Rev.8
July 30, 2009
Permit No:
(to be assigned by DWQ)
Red triangles at the upper right hand corner indicate design comments
Please complete the yellow shaded items.
PIMA
1 t?r
WDENR " V¦W? ¦VY?1 i
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part lll) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Albemarle-Stanly County Airport New Terminal Building
Contact name Ron Geiger
Phone number 704-338.6825
Date July 16, 2009
Drainage area number A
,II. DESIGN INFORMATION
Site Characteristics
Drainage area 292,455.10 ft2
Impervious area 195,078.00 ft2
Percent impervious 66.7% %
Design rainfall depth 1.0 inch
Peak Flow Calculations
Is pre/post control of the 1-yr, 24-hr peak flow required? (Y or N)
1-yr, 24-hr runoff depth 3.02 in
1-yr, 24-hr intensity 0.13 in/hr
Pre-development 1-yr, 24-hr peak flow 0.52 ft3/sec Q = CIA = 0.6*0.13*292455/43560
Post-development 1-yr, 24-hr peak flow 0.56 ft3/sec Q = CIA = 0.64*0.13*292,455/43560
Pre/Post 1-yr, 24-hr peak control 0.03 ft3/sec
Storage Volume: Non-SA Waters
Minimum volume required 17,874.39 ft3
Volume provided 17,908.0 ft3 OK
Storage Volume: SA Waters
1.5' runoff volume ft3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required 0 ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 15984.00 ft2 Insufficient surface area.
Length: 222.00 ft OK
Width: 72.00 ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume 7.98 hr OK
Drawdown time, to 24 inches below surface 15.97 hr OK
Drawdown time, total: 23.95 hr
In-situ soil
Soil permeability 0.01 in/hr Insufficient. Increase infiltration rate.
Planting media soil:
Soil permeability 1.50 in/hr OK
Soil composition
% Sand (by weight) 85% OK
% Fines (by weight) 10% OK
% Organic (by weight) 5% OK
Total: 100%
Phosphorus Index (P-Index) of media (unitless)
Form SW401-Bioretention-Rev.8
July 30, 2009
Permit No:
(to be assigned by DWQ)
Basin Elevations
Temporary pool elevation 575.00 fmsl
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell? y (Y or N) OK
Is this a cell with trees/shrubs? n (Y or N)
Planting elevation (top of the mulch or grass sod layer) 574 fmsl
Depth of mulch 2 inches OK
Bottom of the planting media soil 571.8 fmsl
Planting media depth 2.2 ft
Depth of washed sand below planting media soil 0.3 ft
Are underdrains being installed? y (Y or N)
How many clean out pipes are being installed? 16 OK
What factor of safety is used for sizing the underdrains? (See 4 OK
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and 1 ft
the bottom of the cell to account for underdrains
Bottom of the cell required 570.5 fmsl
SHWT elevation 565 fmsl
Distance from bottom to SHWT 5.5 ft OK
Internal Water Storage Zone (IWS)
Does the design include IWS
Elevation of the top of the upturned elbow
Separation of IWS and Surface
Planting Plan
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
Y (Y or N)
570.7 fmsl
3.3 ft OK
0
0
1 Recommend more species.
Additional Information
Does volume in excess of the design volume bypass the y (Y or N) OK
bioretention cell?
Does volume in excess of the design volume flow evenly y (Y or N) OK
distributed through a vegetated filter?
What is the length of the vegetated filter? 30 ft
Does the design use a level spreader to evenly distribute flow? y (Y or N) Submit a level spreader supplement.
Is the BMP located at least 30 feet from surface waters (50 feet if y (Y or N) OK
SA waters)?
Is the BMP located at least 100 feet from water supply wells? y (Y or N) OK
Are the vegetated side slopes equal to or less than 3:1? y (Y or N) OK
Is the BMP located in a proposed drainage easement with access y (Y or N) OK
to a public Right of Way (ROW)?
Inlet velocity (from treatment system) 0.9 ft/sec OK
Is the area surrounding the cell likely to undergo development in n (Y or N) OK
the future?
Are the slopes draining to the bioretention cell greater than 20%? n (Y or N) OK
Is the drainage area permanently stabilized? y (Y or N) OK
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(8*inches gravel followed by 3-5 ft of grass) x
Grassed swale n OK
Forebay n
Other
Form SW401-Bioretention-Rev.8
July 30, 2009
Permit No:
(to be assigned by DWQ)
III. REQUIRED ITEMS CHECKLIST
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to
indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a
requirement has not been met, attach justification.
Pagel Plan
Initials Sheet No.
TBI/HDR PLAN 2 1. Plans (1" - 50' or larger) of the entire site showing:
Design at ultimate build-out,
Off-site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Cell dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
TBI/HDR PLAN 2 2. Plan details (1" = 30' or larger) for the bioretention cell showing:
Cell dimensions
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Design at ultimate build-out,
Off-site drainage (if applicable),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
TBI/HDR PLAN 3 3. Section view of the bioretention cell (1" = 20' or larger) showing:
Side slopes, 3:1 or lower
Underdrain system (if applicable), and
Bioretention cell layers [ground level and slope, pre-treatment, ponding depth, mulch depth, fill media
depth, washed sand, filter fabric (or choking stone if applicable), #57 stone, underdrains (if applicable),
SHWT level(s), and overflow structure]
TBI ENCLOSED 4. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. The
results of the soils report must be verified in the field by DWQ, by completing & submitting the soils
investigation request form. County soil maps are not an acceptable source of soils information. All
elevations shall be in feet mean sea level (fmsl). Results of soils tests of both the planting soil and the in
situ soil must include:
Soil permeability,
Soil composition (% sand, % fines, % organic), and
P-index.
N/A 5. A detailed planting plan (1" = 20' or larger) prepared by a qualified individual showing:
A variety of suitable species,
Sizes, spacing and locations of plantings,
Total quantity of each type of plant specified,
A planting detail,
The source nursery for the plants, and
Fertilizer and watering requirements to establish vegetation.
HDR PLAN 2 6. A construction sequence that shows how the bioretention cell will be protected from sediment until the
entire drainage area is stabilized.
HDR CALLS 7. The supporting calculations (including underdrain calculations, if applicable).
TBI/HDR ENCLOSED g A copy of the signed and notarized operation and maintenance (0&M) agreement.
N/A 9. A copy of the deed restrictions (if required).
Form SW401-Bioretention-Rev.8
July 30, 2009
NCDENR
?r
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER, FILTER STRIP AND RESTORED RIPARIAN BUFFER SUPPLEMENT
This form must be completely filled out, printed and submitted.
DO NOT FORGET TO ATTACH THE REQUIRED ITEMS CHECKLIST AND ALL REQUIRED ITEMS (NEXT WORKSHEET)!
I. PROJECT INFORMATION
Project name Albemarle-Stanly County Airport New Terminal Building
Contact name Ron Geiger
Phone number 704-338-6825
Date August 21, 2009
Drainage area number A
11. DESIGN INFORMATION
For Level Spreaders Receiving Flow From a BMP
Type of BMP
Drawdown flow from the BMP cfs
For Level Spreaders Receiving Flow from the Drainage Area
Drainage area 292,455.10 ft2
Impervious surface area 195,078.00 ft2
Percent impervious 66.70 %
Rational C coefficient 0.64
Peak flow from the 1 in/hr storm 4.30 cfs
Time of concentration 5.80 min
Rainfall intensity, 10-yr storm 5.8 in/hr
Peak flow from the 10-yr storm 24.92 cfs
Where Does the Level Spreader Discharge?
To a grassed bioretention cell? y (Y or N) Do not complete filter strip characterization below.
To a mulched bioretention cell? y (Y or N) Do not complete filter strip characterization below.
To a wetland? n (Y or N)
To a filter strip or riparian buffer? n (Y or N)
Other (specify)
Filter Strip or Riparian Buffer Characterization (if applicable)
Width of grass ft
Width of dense ground cover ft
Width of wooded vegetation ft
Total width ft
Elevation at downslope base of level lip fmsl
Elevation at top of bank of the receiving water fmsl
Slope (from level lip to to top of bank) %
Are any draws present? (Y or N)
Level Spreader Design
Forebay surface area sq ft
Feet of level lip needed per cfs 13 ft/cfs
Answer "Y" to one of the following:
Length based on the 1 in/hr storm? (Y or N)
Length based on the 10-yr storm? (Y or N)
Length based on the BMP discharge rate? (Y or N)
Design flow cfs
Is a bypass device provided? (Y or N)
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.5 Parts I. and II. Design Summary, page 1 of 2
Length of the level lip ft
Are level spreaders in series? (Y or N)
Bypass Channel Design (if applicable)
Does the bypass discharge through a wetland? (Y or N)
Does the channel enter the stream at an angle? (Y or N)
Dimensions of the channel (see diagram below):
M ft
B ft
W ft
y ft
Peak velocity in the channel during the 10-yr storm cfs
Channel lining material
? W
N

t y 1
?--------- 000. ------
M
M

j B j
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.5 Parts I. and II. Design Summary, page 2 of 2
III. REQUIRED ITEMS CHECKLIST
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to
indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a
requirement has not been met, attach justification.
Page/ Plan
Initials Sheet No.
TBI/HDR PLAN 2 1. Plans (1" 50' or larger) of the entire site showing:
Design at ultimate build-out,
Off-site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
- Forebay (if applicable),
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW), and
Boundaries of drainage easement.
TBI/HDR PLAN 2 2. Plan details (1" = 30' or larger) for the level spreader showing:
Forebay (if applicable),
High flow bypass system,
- One foot topo lines between the level lip and top of stream bank,
Proposed drainage easement, and
Design at ultimate build-out.
TBI/HDR PLAN 2 3. Section view of the level spreader (1" = 20' or larger) showing:
Underdrain system (if applicable),
Level lip,
Upslope channel, and
Downslope filter fabric.
n/a Design Phase 4. A date-stamped photograph of the filter strip that clearly shows the type of vegetation that is present.
TBI/HDR PLAN 2 5. A construction sequence that shows how the level spreader will be protected from sediment until the
entire drainage area is stabilized.
HDR CALCS 6. The supporting calculations.
TBI/HDR ENCLOSED A copy of the signed and notarized operation and maintenance (0&M) agreement.
n/a 8. A copy of the deed restrictions (if required).
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.5 Part III, page 1 of 1
-R
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• • • • •
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NEW LONDON BADIN o p ~
ALBEMARLE- LAKE PAULS CROSSING STANLY r ~ ,ets'P
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MILLINGPORT 52 740
SHEET INDEX
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SHEET N0. SHEET TITLE
73
1 COVER SHEET
2 GRADING/STORM WATER MANAGEMENT PLAN
ALBEMARLE
BLOOMINGTON eY• Q~ 3 BIO-RETENTION DETAILS
~ 73, 27 c ~h
0
RIVER HAVEN
• PROJECT SITE
HILLS °
52 ' ° 27
138
RED CROSS FROG POND
PORTER
LAKE
LOCUST TILLERY
SITE PLAN
NOT TO SCALE NOT TO NOT TO SCALE
SET #
TALBERT&BRIGHT
ENGINEERING & PLANNING CONSULTANTS
3 4944 PARKWAY PLAZA BOULEVARD, SUITE 350
0 rc CHARLOTTE, NORTH CAROLINA 28217
0 U M PHONE: [phone] FAX: 704.426,6080
O O O NORTH CAROLINA LICENSE NO. CA 163
www.talbertandbright.com
L

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! BIORETENTI N ti t : i
UNDERD AI OU~FALL ~ SWALE ~ ~ TEM f0 AR R K
,WITH 0 T ET ~ , ~ ; 4) r'`
~ ~RQT CTIO ) ~ FILTER $ Fr
f ~ 1 F 3
~ r ~ A ~ ~ ~ ~7 ~ ~ ~ ~ , f _ ~ ~ s
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IZ c ~ ~ ~ ~ r ~ ~ ~ (n
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t
, BIQR~T~ENTION ,s f ~ ' 1 ~ WETLAND AREA pQ ~ 0
~ ~ DRAINAGE ~ 5f + - 1 t' l \ Z 58 ~ j l~ ~ a
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j 85
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, DAM #5
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the i ~ r s $ f 'e /
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t~ ~ ~ ~ - EXISTING CONTOUR ~ ~ ~
1 ~ ~
~ ~699~ PROPOSED CONTOUR ~ W
~700~ PROPOSED INDEX CONTOUR ~ Q
T-HANGAR
1 ~ w ~ ~ ~ FILTER STRIP ~ ~
f ~ ~ Q ~ W
1 s ~ BIORETENTION ~ ~ ~
W ~ ~ j ~ ~ ~ ~
~ ~ Z v
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NOTES:
1. CONTRACTOR SHALL SEED/MULCH, AND INSTALL MATTING TO TALBERT&BRIGHT
STABILITZE SIDE SLOPES OF BIO-RETENTION SWALE PRIOR 50 25 0 50 100 150
L'AT!'`_TAT~TrDiAT!`_ ;C. DT AAT1~TiAT!'`_ MT`TCT Ti TA1`1TC
TO INSTALLATION OF THE FILL/SOIL MEDIA. 1 ` X
4944 PARKWAY PLAZA BOULEVARD' S= 350 SHT.
2. BMP'S ARE LOCATED ON A PUBLIC AIRPORT AND CAN BE SCALE IN FEET CHARLOTTENORTH CAROLINA 28217
ACCESS FOR MAINTENANCE AS NEEDED. 1"=50' HDR Engineering, Inc. PHONE: [phone] FAX: [phone] of the Carolinas NORTH CAROLINA LICENSE NO. C, 1163
www.talbertandbright.com OF 3
ROAD IS OWNED BY STANLY COUNTY. 128 S Tryon Street, Suite 1400 1 Charlotte, NC 28202
L 3. ALL THE PROPERTY SHOWN TO THE WEST OF AIRPORT

W
Q °
BIO-RETENTION SWALE TABLE
SURFACE L W
BIO SWALE ID ELEVATION (FEET) (FEET) Z O
E1 574.00 242 74
w
4" UNDERDRAIN, ,
LENGTH=0.8W 5 A (TYP.)
L
N ~ ~ ~
~n ~
B B 0 B
0
> ~ o m >
w U Q ~ ~ U °
NOTE 1 -NOTE 1
~ ~ o
m z ~ m w w z } ~
m w ° ~
A LONGITUDINAL CONNECT -CONNECT UNDERDRAIN ~ w ~
UNDERDRAIN TO INLET TO INLET OR DAYLIGHT ~n o o Q w w
LIMITS OF MEDIA AS SHOWf~ w ~ cc ~ z Q AS SHOWN ON PLANS ° w w ° ~ °
LIMITS OF GRASS ESTABLISHED CLEAN-OUT RISER BY PERMANENT SODDING TYP.
( )
NOT TO SCALE
FBI
NOTE: ZZO
1. UNDERDRAIN PIPE OUTSIDE OF MEDIA,
AND CLEAN-OUT RISER TO BE SOLID ~a
4" PIPE. REMAINING PIPE TO BE
H ~ 0~
PERFORATED WITH MIMIMUM 4" N0. 57 STONE AROUND ALL SIDES.
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W
3 4" CLEAN OUT 3
~1 RISER W CAP 1~
BIORETENTION SURFACE JRFACE EARTHEN BERM
ELEVATION 574.00 )0 BIO-SWALE ~~4'' OVERFLOW
- - - L= 222 ~
GRASS L-2
IN-SITU SOIL ~ ESTABLISHED IN-SITU SOIL 4" CLEAN 2 -4" CLEAN OUT RISER W/CAP
BY SODDING 1,
f
~t
2'
TO UNDERDRAIN
FILTER FABRIC (AMOCO PROPEX 4" WASHED SAND ' COLLECTOR
4551, MIRAFI 160N, OR APPROVED
EQUAL) 8" N0. 57 STONE (TYP.) FILTER FABRIC 4" LONGITUDINAL UDINAL 2' FILL/SOIL MEDIA
4" LONGITUDINAL UNDERDRAIN (AMOCO PROPEX UNDERDRAIN, GRADE .IN, GRADE 4" WASHED SAND 85% SAND,
4" UNDERDRAIN, 2' FILL SOIL MEDIA 4551, MIRAFI 160N, TO DAYLIGHT AS BHT AS 8" N0. 57 STONE 10% FINES,
PERFORATED PIPE 85% SAND OR APPROVED SHOWN ON PLANS J PLANS 5% ORGANIC
4" LONGITUDINAL UNDERDRAIN 10% FINES EQUAL) GRASS ESTABLISHED
5% ORGANIC BY SODDING
SECTION B-B
- - -RETENTION SWALE
NOT TO SCALE NOT NOT TO SCALE J ~ o
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NOTES: Q U
1. PERFORATED UNDERDRAIN PIPE SHALL BE WRAPPED WITH FILTER FABRIC. W
2. ALL WORK REQUIRED TO CONSTRUCT THE BIORETENTION SWALE
SHALL BE IN ACCORDANCE WITH THE REQUIREMENTS IDENTIFIED ON THE PLANS AND SHALL BE PAID FOR AT THE CONTRACT UNIT ~ 0
PRICE FOR THE "BIORETENTION SWALE" ITEM OF WORK. o~C ~
3. DO NOT INSTALL BIO-RETENTION FILTER MEDIA LAYERS AND
UNDERDRAIN SYSTEM UNTIL AREAS DRAINING TO BIO-RETENTION SWALE ARE STABILIZED. a w
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TALBERT&BRIGHT
L'AT!'`_TAT~TrDiAT!`_ ;C. DT AAT1~TiAT!'`_ MT`TCT Ti TA1`1TC
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4944 PARKWAY PLAZA BOULEVARD' S= 350 SHT.
CHARLOTTENORTH CAROLINA 28217
HDR Engineering, Inc. PHONE: [phone] FAX: [phone] of the Carolinas NORTH CAROLINA LICENSE NO. C, 1163
www.talbertandbright.com OF 3
128 S Tryon Street, Suite 1400 1 Charlotte, NC 28202