20090842 Ver 1_More Info Received_20100205

ALPHA & OMEGA GROUP
C I V I L & S T R U C T U R A L L N G I N F r R S
LETTER OF TRANSMITTAL
TO: Cyndi Karoly, Supervisor
NC DWQ, 401/ Wetlands Unit
2321 Crabtree Blvd.
Raleigh, NC, 27604
Suite 250
FROM: T. Glenn Zeblo, P.E.z
DATE: February 4, 2010
Telephone: [phone]
Facsimile: 919-733-6893
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VOLANDS AND ST I ORMI ATER BRANCH
RE: PCN Application DWQ 2009-0842, Wake County
UT to Crabtree Creek [030402,27-33-(10), C, NSW]
First Assembly of God of Raleigh (City of Raleigh # SP-103-08)
WE ARE SENDING YOU:
COPIES: DATE: Nn_ T)RRC'RTPTION-
5 2-4-10 1 Written Responses to DWQ Letter dated 1/6/10
requesting additional information
5 66 2 Revised Stormwater Management Calculations
5 3 Specification for Turf and Grasses
5 46 4 Full size plan sheets
1 46 5 Compact Disc with electronic TIFF files of plan sheets

THESE ARE TRANSMITTED: For review and approval.
COMMENTS: We are providing this additional information per your request in your letter dated
1-6-10. Please feel free to contact me should you have any questions or need additional
information. I would like to meet with you to discuss any further comments to hopefully resolve
your review if needed. Thanks.
Cc: File; Mr. David Allsbrook - First Assembly of God of Raleigh
p:\2008_000\2008 021 - first assembly church\corresp\transmittal\nc dwq pcn sumittal 2-4-10.doc
4911 Green Road Suite 107 Raleigh, North Carolina 27616 Phone [phone] Fax [phone] uautu.aogroup.com

ALPHA & OMEGA GROUP
C I V I L & S T R U C T U R A L E N G I N E E R 5
February 4, 2010
Ms. Cyndi Karoly, Supervisor
401 Oversight/Express Review Permitting Unit
NCDENR - DWQ
2321 Crabtree Boulevard
Raleigh, NC 27604
Re: DWQ Project #2009-0842, Wake County
First Assembly of God, Raleigh
UT to Crabtree Creek [030402,27-33-(10), C, NSW]
Dear Ms. Karoly:
This letter is a written response to your request for additional information by letter dated January
6, 2010. I have included herein your written requests/comments with our written response in bold
text below each numbered item. We are providing five (5) copies of the additional information
per your request.
Additional Information Requested:
1. Please provide full-sized plan sheets of the entire site at a scale of 1" = 50' or larger.
Response: We have provided the following full-sized plan sheets per your request:
Cover Sheet - shows the entire site at 1"=100'
C0.0 - Topographic Survey of entire site at 111=50'
C1.0 - Demolition Plan that shows the site area that is affected by construction at 1"=40'
C2.0 - Grading Plan that shows the entire site at 111=50'
C2.1- Drainage Calculations Plan - Details: Detention Pond, Bypass Manhole w/ Diverter,
Level Spreader, Detention Outlet Structure, Piped Storm Drainage Chart, Level Spreader
Plan at 1"=30'
C2.2 - Pre & Post Drainage Area Plan - Pre & Post Plans at 111=100' with Pre & Post Tables
C3.0 - Site Plan - plan of entire site at 1"=50'
We have not provided the Utility, Blue Ridge Road Widening, Landscape or Parking Lot
Lighting Plans as they do not disturb the NRRB. There is no land disturbance on the west
side of the Tributary "D" proposed with this project.
2. Per the requirements of the Neuse Riparian Buffer Rule, the stormwater that is discharged from the
dry detention basin during the design storm must be discharged through a correctly designed level
P:\2008_000\2008021 -first assembly church\corresp\reviews\ncdwq\written responses to dwq letter_2-I-IO.doc
4911 Green Road Suite 107 Raleigh, North Carolina 27616 Phone [phone] Fax [phone] u,wtu.aogroup.com
First Assembly of God
February 4, 2010
Page 2 of 3
spreader. Level spreader design requirements are set forth in Chapter 8 of the North Carolina
Stormwater BMP Manual, available at: http://h2o.enr.state.ne.us/su/bmp forms.htm. Please pro-
vide a Level Spreader Supplement Form for each proposed level spreader, available at the same
web site. Please include the Required Items checklist and all items listed therein.
Response: This comment is the same comment from the previous review. Per your previous
request, we downloaded DWQ's Level Spreader supplemental spreadsheet and completed it
and provided the print-out along with all additional items requested in the checklist in Section
HI. Since there is no specific comment otherwise provided relating to this supplement form, I
can only assume that this comment was an oversight and either not edited or not removed.
Please advise.
3. Please provide plan details for the proposed dry detention basin, including a table of elevations and
incremental storage volumes.
Response: Plan details of the proposed dry detention basin are located on plan sheet C2.1 re-
ferenced above in comment no. 1. A Stage/Storage Table of elevations and incremental sto-
rage volumes can be found on page 16 of the revised stormwater management report dated
2/3/2010 submitted herewith.
Please explain why the storm intensity decreases from 5.78 to 1.33 in/hr throughout a 60-minute
storm duration as shown on the submitted spreadsheet.
Response: I have assumed that the Time of Concentration (Tc) is equal to the duration of the
storm event (Td). Using the generally accepted formula: I = G/T + H.
Where:
I = intensity
G = 104 (for a 1 yr event)
T = Tc=Td (time of concentration is assumed to equal time of duration)
H =18 (for a 1 yr event)
The storm intensity decreases as time increases. This is based on the standard IDF for Ra-
leigh developed by Dr. H. R. Malcom, NCSU.
Based on the DWQ's calculations, it appears that the peak flow from the proposed dry detention
basin will be much greater than 1.83 cfs as stated. If that is the case, the system will need to be re-
designed for the appropriate flow rate.
Response: The peak flow from the dry detention basin is calculated to be 8.138 cfs for the 10-
yr storm event (page 13 of the Stormwater Management Report dated 2/3-2010). We have
designed a manhole w/ a diverter weir to divert the 1-yr storm event to the proposed level
spreader to accommodate 1.84 cfs based on the spreadsheet provided to you in the previous
response documentation. The Hydraflow software used has computed the 1-yr discharge to
be 1.504 cfs (page 13 of the Stormwater Management Report dated 2/3-2010). We have cho-
sen to use the 1.84 cfs (based on our spreadsheet) to design the Level Spreader since it is
more conservative. The remaining flow of 6.298 cfs (8.138 - 1.84) is proposed to be dis-
First Assembly of God
February 4, 2010
Page 3 of 3
charged through the bypass pipe from the diverter manhole to the stream in accordance with
the latest BMP manual. An energy dissapator pad has been sized to accommodate the now
velocity for partial flow since there is no known plunge pool in the subject feature, in accor-
dance with the latest BMP manual. Please refer to plan sheet C2.1 for Manhole w/ Diverter
details and elevations.
4. Please provide specifications for topsoil and sod in the filter strip downslope of the proposed level
spreader. Please provide watering specifications to establish the sod.
Response: Specification Section 329200 - Turf and Grasses is provided for your review.
5. We have updated the design calculations and the plans and therefore have provided one (1) data
CD of full size plans in PDF or TIFF Group 4 format (black and white, not grayscale or color).
Thank you for the opportunity to provide this additional information. Please do not hesitate to
contact me should you require more information.
Sincerely,
Alpha & Omega Group
T. Glenn Zeblo, PE
Vice President
/File
Mr. David Allsbrook, First Assembly of God of Raleigh
Section 329200 - Turf and Grasses
PART 1 - GENERAL
1.1 SUMMARY
A. Section Includes:
1. Seeding.
2. Sodding.
1.2 DEFINITIONS
A. Duff Layer: The surface layer of native topsoil that is composed of mostly decayed leaves,
twigs, and detritus.
B. Finish Grade: Elevation of finished surface of planting soil.
C. Manufactured Topsoil: Soil produced off-site by homogeneously blending mineral soils or sand
with stabilized organic soil amendments to produce topsoil or planting soil.
D. Pesticide: A substance or mixture intended for preventing, destroying, repelling, or mitigating a
pest. This includes insecticides, miticides, herbicides, fungicides, rodenticides, and
molluscicides. It also includes substances or mixtures intended for use as a plant regulator,
defoliant, or desiccant.
E. Pests: Living organisms that occur where they are not desired or that cause damage to plants,
animals, or people. These include insects, mites, grubs, mollusks (snails and slugs), rodents
(gophers, moles, and mice), unwanted plants (weeds), fungi, bacteria, and viruses.
F. Planting Soil: Standardized topsoil; existing, native surface topsoil; existing, in-place surface
soil; imported topsoil; or manufactured topsoil that is modified with soil amendments and
perhaps fertilizers to produce a soil mixture best for plant growth.
G. Subgrade: Surface or elevation of subsoil remaining after excavation is complete, or top surface
of a fill or backfill before planting soil is placed.
H. Subsoil: All soil beneath the topsoil layer of the soil profile, and typified by the lack of organic
matter and soil organisms.
1. Surface Soil: Whatever soil is present at the top layer of the existing soil profile at the Project
site. In undisturbed areas, the surface soil is typically topsoil, but in disturbed areas such as
urban environments, the surface soil can be subsoil.
1.3 SUBMITTALS
A. Product Data: For each type of product indicated.
B. Certification of grass seed.
208017 329200-1
Section 329200 - Turf and Grasses
1. Certification of each seed mixture for turfgrass sod.
C. Product certificates.
1.4 QUALITY ASSURANCE
A. Installer's Field Supervision: Require Installer to maintain an experienced full-time supervisor
on Project site when work is in progress.
Pesticide Applicator: State licensed, commercial.
B. Soil Analysis: For each unamended soil type, furnish soil analysis and a written report by a
qualified soil-testing laboratory.
1. The soil-testing laboratory shall oversee soil sampling.
2. Report suitability of tested soil for turf growth.
a. State recommendations for nitrogen, phosphorus, and potash nutrients and soil
amendments to be added to produce satisfactory planting soil suitable for healthy,
viable plants.
b. Report presence of problem salts, minerals, or heavy metals; if present, provide
additional recommendations for corrective action.
1.5 DELIVERY, STORAGE, AND HANDLING
A. Seed and Other Packaged Materials: Deliver packaged materials in original, unopened
containers showing weight, certified analysis, name and address of manufacturer, and indication
of conformance with state and federal laws, as applicable.
B. Sod: Harvest, deliver, store, and handle sod according to requirements in "Specifications for
Turfgrass Sod Materials" and "Specifications for Turfgrass Sod Transplanting and Installation"
in TPI's "Guideline Specifications to Turfgrass Sodding." Deliver sod in time for planting
within 24 hours of harvesting. Protect sod from breakage and drying.
1.6 MAINTENANCE SERVICE
A. Initial Turf Maintenance Service: Provide full maintenance by skilled employees of landscape
Installer. Maintain as required in Part 3. Begin maintenance immediately after each area is
planted and continue until acceptable turf is established but for not less than the following
periods:
Seeded Turf. 30 days from date of planting completion.
a. When initial maintenance period has not elapsed before end of planting season, or
if turf is not fully established, continue maintenance during next planting season.
2. Sodded Turf: 30 days from date of planting completion.
208017 329200-2
Section 329200 - Turf and Grasses
PART 2 - PRODUCTS
2.1 SEED
A. Grass Seed: Fresh, clean, dry, new-crop seed complying with AOSA's "Journal of Seed
Technology; Rules for Testing Seeds" for purity and germination tolerances.
B. Seed Species: State-certified seed of grass species as follows:
1. Full Sun: Tall Fescue.
2. Sun and Partial Shade: Tall Fescue
3. Shade: Tall Fescue
2.2 TURFGRASS SOD
2.2 TURFGRASS SOD
A. Turfgrass Sod: Approved Number 1 Quality/Premium, including limitations on thatch, weeds,
diseases, nematodes, and insects, complying with "Specifications for Turfgrass Sod Materials"
in TPI's "Guideline Specifications to Turfgrass Sodding." Furnish viable sod of uniform
density, color, and texture, strongly rooted, and capable of vigorous growth and development
when planted.
B. Turfgrass Species: Sod of grass species as follows:
1. Full Sun: Tall Fescue.
2. Sun and Partial Shade: Tall Fescue
3. Shade: Tall Fescue
2.3 INORGANIC SOIL AMENDMENTS
A. Lime: ASTM C 602, agricultural liming material containing a minimum of 80 percent calcium
carbonate equivalent and as follows:
1. Class: O, with a minimum of 95 percent passing through No. 8 sieve and a minimum of
55 percent passing through No. 60 sieve.
B. Sulfur: Granular, biodegradable, containing a minimum of 90 percent sulfur, and with a
minimum of 99 percent passing through No. 6 sieve and a maximum of 10 percent passing
through No. 40 sieve.
C. Iron Sulfate: Granulated ferrous sulfate containing a minimum of 20 percent iron and 10
percent sulfur.
D. Aluminum Sulfate: Commercial grade, unadulterated.
208017 329200-3
Section 329200 - Turf and Grasses
E. Perlite: Horticultural perlite, soil amendment grade.
F. Agricultural Gypsum: Minimum 90 percent calcium sulfate, finely ground with 90 percent
passing through No. 50 sieve.
G. Sand: Clean, washed, natural or manufactured, and free of toxic materials.
H. Diatomaceous Earth: Calcined, 90 percent silica, with approximately 140 percent water
absorption capacity by weight.
1. Zeolites: Mineral clinoptilolite with at least 60 percent water absorption by weight.
2.4 ORGANIC SOIL AMENDMENTS
A. Compost: Well-composted, stable, and weed-free organic matter, pH range of 5.5 to 8;
moisture content 35 to 55 percent by weight; 100 percent passing through 3/4-inch sieve;
soluble salt content of 5 to 10 decisiemens/m; not exceeding 0.5 percent inert contaminants and
free of substances toxic to plantings.
B. Sphagnum Peat: Partially decomposed sphagnum peat moss, finely divided or of granular
texture, with a pH range of 3.4 to 4.8.
C. Muck Peat: Partially decomposed moss peat, native peat, or reed-sedge peat, finely divided or
of granular texture, with a pH range of 6 to 7.5, and having a water-absorbing capacity of 1100
to 2000 percent.
D. Wood Derivatives: Decomposed, nitrogen-treated sawdust, ground bark, or wood waste; of
uniform texture and free of chips, stones, sticks, soil, or toxic materials.
E. Manure: Well-rotted, unleached, stable or cattle manure containing not more than 25 percent by
volume of straw, sawdust, or other bedding materials; free of toxic substances, stones, sticks,
soil, weed seed, and material harmful to plant growth.
2.5 FERTILIZERS
A. Bonemeal: Commercial, raw or steamed, finely ground; a minimum of 1 percent nitrogen and
10 percent phosphoric acid.
B. Superphosphate: Commercial, phosphate mixture, soluble; a minimum of 20 percent available
phosphoric acid.
C. Commercial Fertilizer: Commercial-grade complete fertilizer of neutral character, consisting of
fast- and slow-release nitrogen, 50 percent derived from natural organic sources of urea
formaldehyde, phosphorous, and potassium in the following composition:
Composition: 25 lb/1000 sq. ft. of actual nitrogen, 10 percent phosphorous, and 10
percent potassium, by weight.
D. Slow-Release Fertilizer: Granular or pelleted fertilizer consisting of 50 percent water-insoluble
nitrogen, phosphorus, and potassium in the following composition:
208017 329200-4
Section 329200 - Turf and Grasses
Composition: 10 percent nitrogen, 10 percent phosphorous, and 10 percent potassium, by
weight.
2.6 PLANTING SOILS
A. Planting Soil : Existing, native surface topsoil formed under natural conditions with the duff
layer retained during excavation process. Verify suitability of soil to produce viable planting
soil. Clean soil of roots, plants, sod, stones, clods, clay lumps, pockets of coarse sand, concrete
slurry, concrete layers or chunks, cement, plaster, building debris, and other extraneous
materials harmful to plant growth. Mix soil with the following soil amendments and fertilizers
in the following quantities to produce planting soil:
1. Weight of Commercial Fertilizer per 1000 Sq. Ft.: 25 lbs.
2. Weight of Slow-Release Fertilizer per 1000 Sq. Ft.: 25 lbs.
2.7 MULCHES
A. Straw Mulch: Provide air-dry, clean, mildew- and seed-free, salt hay or threshed straw of
wheat, rye, oats, or barley.
2.8 PESTICIDES
2.8 PESTICIDES
2.8 PESTICIDES
A. General: Pesticide, registered and approved by EPA, acceptable to authorities having
jurisdiction, and of type recommended by manufacturer for each specific problem and as
required for Project conditions and application. Do not use restricted pesticides unless
authorized in writing by authorities having jurisdiction.
PART 3 - EXECUTION
3.1 TURF AREA PREPARATION
A. Newly Graded Subgrades: Loosen subgrade to a minimum depth of 6 inches. Remove stones
larger than 1 inch in any dimension and sticks, roots; rubbish, and other extraneous matter and
legally dispose of them off Owner's property.
1. Apply fertilizer directly to subgrade before loosening.
2. Thoroughly blend planting soil off-site before spreading or spread topsoil, apply soil
amendments and fertilizer on surface, and thoroughly blend planting soil.
3. Spread planting soil to a depth of 4 inches but not less than required to meet fmish grades
after light rolling and natural settlement. Do not spread if planting soil or subgrade is
frozen, muddy, or excessively wet.
208017 329200-5
Section 329200 - Turf and Grasses
a. Reduce elevation of planting soil to allow for soil thickness of sod.
B. Unchanged Subgrades: If turf is to be planted in areas unaltered or undisturbed by excavating,
grading, or surface-soil stripping operations, prepare surface soil as follows:
1. Remove existing grass, vegetation, and turf. Do not mix into surface soil.
2. Loosen surface soil to a depth of at least 6 inches. Apply soil amendments and fertilizers
according to planting soil mix proportions and mix thoroughly into top 6 inches of soil.
Till soil to a homogeneous mixture of fine texture.
a. Apply fertilizer directly to surface soil before loosening.
3. Remove stones larger than 1 inch in any dimension and sticks, roots, trash, and other
extraneous matter.
4. Legally dispose of waste material, including grass, vegetation, and turf, off Owner's
property.
C. Finish Grading: Grade planting areas to a smooth, uniform surface plane with loose, uniformly
fine texture. Grade to within plus or minus 1/2 inch of finish elevation. Roll and rake, remove
ridges, and fill depressions to meet finish grades. Limit finish grading to areas that can be
planted in the immediate future.
D. Moisten prepared area before planting if soil is dry. Water thoroughly and allow surface to dry
before planting. Do not create muddy soil.
E. Before planting, obtain Architect's acceptance of finish grading; restore planting areas if eroded
or otherwise disturbed after finish grading.
3.2 SEEDING
A. Do not broadcast or drop seed when wind velocity exceeds 5 mph. Evenly distribute seed by
sowing equal quantities in two directions at right angles to each other. Do not seed against
existing trees. Limit extent of seed to outside edge of planting saucer.
B. Sow seed at a total rate of 2 lb/1000 sq. ft..
C. Rake seed lightly into top 1/8 inch of soil, roll lightly, and water with fine spray.
D. Protect seeded areas with slopes not exceeding 1:6 by spreading straw mulch. Spread uniformly
at a minimum rate of 2 tons/acre to form a continuous blanket 1-1/2 inches in loose thickness
over seeded areas. Spread by hand, blower, or other suitable equipment.
1. Anchor straw mulch by crimping into soil with suitable mechanical equipment.
E. Protect seeded areas from hot, dry weather or drying winds by applying planting soil within 24
hours after completing seeding operations. Soak areas, scatter mulch uniformly to a thickness
of 3/16 inch, and roll surface smooth.
208017 329200-6
Section 329200 - Turf and Grasses
3.3 SODDING
A. Lay sod within 24 hours of harvesting. Do not lay sod if dormant or if ground is frozen or
muddy.
B. Lay sod to form a solid mass with tightly fitted joints. Butt ends and sides of sod; do not stretch
or overlap. Stagger sod strips or pads to offset joints in adjacent courses. Avoid damage to
subgrade or sod during installation. Tamp and roll lightly to ensure contact with subgrade,
eliminate air pockets, and form a smooth surface. Work sifted soil or fine sand into minor
cracks between pieces of sod; remove excess to avoid smothering sod and adjacent grass.
1. Lay sod across angle of slopes exceeding 1:3.
2. Anchor sod on slopes exceeding 1:6 with wood pegs or steel staples spaced as
recommended by sod manufacturer but not less than 2 anchors per sod strip to prevent
slippage.
C. Saturate sod with fine water spray within two hours of planting. During first week after
planting, water daily or more frequently as necessary to maintain moist soil to a minimum depth
of 4 inches below sod.
3.4 TURF MAINTENANCE
A. Maintain and establish turf by watering, fertilizing, weeding, mowing, trimming, replanting, and
performing other operations as required to establish healthy, viable turf. Roll, regrade, and
replant bare or eroded areas and remulch to produce a uniformly smooth turf. Provide materials
and installation the same as those used in the original installation.
B. Mow turf as soon as top growth is tall enough to cut. Repeat mowing to maintain height
appropriate for species without cutting more than 1/3 of grass height. Remove no more than 1/3
of grass-leaf growth in initial or subsequent mowings.
C. Apply pesticides and other chemical products and biological control agents in accordance with
authorities having jurisdiction and manufacturer's written recommendations. Coordinate
applications with Owner's operations and others in proximity to the Work. Notify Owner before
each application is performed.
3.5 SATISFACTORY TURF
A. Turf installations shall meet the following criteria as determined by Architect:
1. Satisfactory Seeded Turf: At end of maintenance period, a healthy, uniform, close stand
of grass has been established, free of weeds and surface irregularities, with coverage
exceeding 90 percent over any 10 sq. ft. and bare spots not exceeding 5 by 5 inches.
2. Satisfactory Sodded Turf: At end of maintenance period, a healthy, well-rooted, even-
colored, viable turf has been established, free of weeds, open joints, bare areas, and
surface irregularities.
B. Use specified materials to reestablish turf that does not comply with requirements and continue
maintenance until turf is satisfactory.
208017 329200-7
Section 329200 - Turf and Grasses
END OF SECTION 329200
208017 329200-8

Revised
Preliminary Stormwater Management
Report
February 3, 2010
First Assembly Church
3249 Blue Ridge Road
Raleigh, North Carolina
Contents:
Stormwater Detention,
Level Spreader and Bypass Flow
Structure

ALPHA & ,OMEGA GROUP
CIVIL & STRUCTURAL ENGINEERS
X1911 Green RnnA Sniie 107 Raleigh. NC: 27616
Phone [phone] mfa&!agm p.cnm mu•n.aogronfi.rorn
ALPHA & OMEGA GROUP
CIVIL & STRUCTURAL ENGINEERS
I HEREBY CERTIFY THAT THESE CALCULATIONS CONTAINED HEREIN WERE
PREPARED BY ME OR UNDER MY DIRECT SUPERVISION.
SIGNED, SEALED, AND DATED THIS DAY OF w 410.
n Zeblo, PE
loofessional Engineer
State of North Carolina
License No. 032724
I:Vnasters\a&ooffice\,tgz calculations certification20 I O.doc
4911 Green Road Suite 107 Raleigh. North Carolina 27616 Phone [phone] Fax [phone] www.aogroup.com
TABLE OF CONTENTS
Narrative
Summary
2
Pre & Post Development Site Calculations 3-11
Dry Pond Calculations
12-24
Splitter Box and Level Spreader Hydraulic 25-32
Grade Line Computations
Pre Development Drainage Areas Exhibit DA-1
Post Development Drainage Areas Exhibit DA-2
BMP Treatment Area Exhibit DA-3
SITE NARRATIVE:
This project involves an addition to an existing building on the First Assembly Church
property located on Blue Ridge Road in the City of Raleigh. Additional class room space
will be added and an additional parking lot will be added. The additional impervious
surface will require storm water runoff control and nitrogen mitigation / buy-down.
The site area is 13.88 acres. There are two existing buildings, three modular class rooms
and two parking lots that contain 387 parking spaces. The site has an existing drainage
system that collects stormwater from the northeastern side of the site and drains it to a
stream (Tributary "D") located on the northern end of the site. The stormwater from the
west side of the site sheet flows to a drainage swale which also drains into the stream on
the northern end of the site. A small drainage area southwest of the site drains into a
drainage swale that is located within the Blue Ridge right of way. The proposed site
will add a building expansion and an additional asphalt parking area. Because of the
building expansion the existing modular buildings will be removed. Since the post
development runoff is over 10% of the pre development runoff we are proposing a dry
detention pond to control the runoff to pre-development flows or less. In addition to the
dry detention pond we are proposing the use of a vegetative filter strip with a level
spreader to work in conjunction with the dry pond to increase nitrogen export control
from the site. The drainage area with the proposed additions will be routed through the
dry detention pond. The dry detention pond discharge will be piped though a splitter box
diverting the 1 "storm to the level spreader and the vegetative filter strip before it is
discharged to the stream (Tributary "D"). The remainder of the pond discharge will be
diverted through the splitter box to the bypass pipe to the stream. Other portions of the
site will continue to drain as they do at present. See Exhibits DA-1 and DA-2 to see the
pre and post development drainage patterns for the site. See Exhibit DA-3 to see the
BMP treatment areas.
?1?2
SUMMARY:
Pre and Post Development Runoff Calculations:
Return Period Existing
2 Yr 44.8 cfs
10 Yr 56.2 cfs
100 Yr 75.6 cfs
Proposed Proposed
w/o Control w/ Control
51.7 cfs 30.1 cfs
64.8 cfs 43.5 cfs
87.2 cfs 65.9 cfs
The proposed improvements would increase the overall stormwater discharge from the
site by 15.33%, exceeding the 10% maximum allowed without stormwater management
control in place.
We are proposing a dry detention pond to control enough of the post construction runoff
to levels that are equal to or less than the pre-developed runoff rates.
232
PRE AND POST DEVELOPMENT RUNOFF CALCULATIONS
3/32
Project Name: First Assembly Church Date:8/5/2009
Project Number: 2008.021
PRE-CONDITIONS AND POST-DEVELOPMENT STORM RUNOFF DATA FOR WHOLE SITE
( W16(A? ?YIT)eoL0)
Cvt&+inn r`nnrll4innc• /aro novolnnmanri Proposed Conditions: (Post Develoment)
Total Area
Building 1.17 acres 50,977 sf
Concrete. 0.22 acres 9,668 sf
As hlt 3.72 acres 162,075
sf
Grav
8' 0.13 acres 5,701 sf
Rubber Chi la are
-
0.03
acres
1 422
sf
g
Grass 6.37 acres 277,662 sf
Woods 2.23 acres 97.110 sf

Total 13.88 acres 604,615 sf
Total Area
Building 1.49 acres 64 903 sf
Concrete 0.41 acres 17,901 sf
Asphalt 4.94 acres 215,095 sf
Gravel 0.18 acres 7,872 sf
Rubber Chi la area 0.00 acres 0 sf
Grass 5.98 acres 260,433 sf
woods 0.88 acres 38,411 sf

Total 13.88 acres 604,615 sf
Forest 2.23 acres
Grass 6.37 acres
Total Impervious area 5.28 acres
Forest 0.88 acres
crass 5.98 acres
Total impervious area 7.02 acre
Proposed impervious surface area increase 33.03%
Total impervious surface area In drainage area 50:57%
r-tips a o (`ih, of P.wd h Afnn m., n-i- KA.-.1
C-Values
C
Building 0.95
Concrete 0.95
Asphalt 0.95
Gravel 0.90
Rubber Mat play area 0.50
Gress 0.35
Woods 0.25

Composite C Values
C
Existing Conditions:
Pre Develo ment 0.56

Proposed Conditions:
Post Develoment 0.65
1 Year Composite C Intensity Area Runoff
Existing Conditions 0.56 4.52 13.88 35.2
Proposed conditions 0.65 4.52 13.88 40.6
% Increase 15.33%
2 Year Composite C Intensity Area Runoff
Existing Conditions 0.56 5.76 13.88 44.8
Proposed conditions 0.65 5.76 13.88 51.7
% Increase 15.33%
10 Year Composite C Intensity Area Runoff
Existing Conditions 0.56 7.22 13.88 56.2
Proposed conditions 0.65 7.22 13.88 64.8
% increase 15.33%
100 Year Composite C Intensity Area Runoff
Existing Conditions 0.56 9.72 13.88 75.6
Proposed conditions 0.65 9.72 13.88 87.2
% Increase 15.33%
The proposed conditions stormwater runoff exceeds the 10% storm water increase limit, detention will be required.
Notes:
Intensities used are from Table 2.3, City of Raleigh, Stormwatar nPCign Mammal.
All Tc=5 min.
Intensity for 1 year storm calculated using I =104/(t+108).
P:\2008000\2008021 - First Assembly Church\eng\Drainage calculations\Overall pre and post calcs to determine if detention is needed\2008-021 overall Pre &
Post cals for detention on site determination 7-6-09.xls
ALPHA OMEGA GROUP ,PC
Project Name: First Assembly Church
Project Number: 2008.021
Date:7/6/2009
PRE CONSTRUCTION IMPERVIO US AND PERVIO US AREAS CHART
DRAINAGE AREA
#1 DRAINAGE AREA
#2 DRAINAGE AREA
#3 UNDISTURBED AREA ON
NORTH SIDE OF STREAM TOTAL SITE
DRAINAGE AREAS
SURFACE TYPE AREAS AREAS AREAS AREAS AREAS
AC) (SF) (AC) SF) (AC) I SF AC SF (AC) (SF)
IMPERVIOUS
ASPHALT 3.08 133,950 0.65 28,125. 0.00 0 0.00 0 3.72 162,075
BUILDING 0.50 21,811 0.67 29,166 0.00 0 0.00 0 1.17 50,977
CONCRETE 0.11 4,717 0.11 4,852 0.00 99 0.00 0 0.22 9,668
GRAVEL 0.02 918 0.03 1,422 0.08 3,361 0.00 0 0.13 . 5,701
RUBBER CHIP 0.00 0 0.03 1,422 0.00 0 0.00 0 0.03 1,422
TOTAL 3.71 161,396 1.49 64,987 0.08 3,460 0.00 0 5.28 229,843
PE RVIOUS
GRASS 2.15 93,867 3.23 140,685
WOODS 0.00 0 1.84 80,083
TOTAL 2.15 93,867 5.07 220,768
TOTAL 5.86 255,263 6.56 285,755
PERCENT IMPERVIOUS AREA ON EXISTING SITE 0.90 39,229
0.00 0
0.90. 39,229
0.98 42,689
38.01% 0.09 3,882
0.39 17,027
0.48 20,909
0.48 20,909 6.37
2.23
8.60
13.88 277,662
97,110
374,772
604,615
POST CONSTRUCTION IMPERVI OUS AND PERVIOUS AREAS CHAR T. ,
DRAINAGE AREA DRAINAGE AREA DRAINAGE AREA UNDISTURBED TOTAL SITE
#1 #2 #3 AREA ON NORTH DRAINAGE AREAS
SIDE OF STREAM
SURFACE TYPE AREAS AREAS AREAS AREAS AREAS
(AC (SF) AC SF (AC) SF (AC) SF (AC) SF
IMPERVIOUS
ASPHALT 3.07 133,939 1.86 81,156 0.00 0 0.00 0 4.94 215,095
BUILDING 0.50 21,811 0.99 43,092 0.00 0 0.00 0 1.49 64,903
CONCRETE 0.22 9,380 0.20 8,521 0.00 0 0.00 0 0.41 17,901
GRAVEL ? 0.02 918 0.16 6,954 0.00 0 0.00 0 0.18 7,872
RUBBER CHIP 0.04 0 040 .._ . -01 .. 0.00 0 . 0:00 ° 0 ' 0.00 0 .
TOTAL 3.81 166,048 3.21 139,723 0.00 0 0.00 0 7.02,.--l 305,771
PE RVIOUS
GRASS 1.82 79,196 4.07 177,356 0.00 0 0.09 3.8821 1 5.98 260,433
WOODS 0.00 0 0.49 21,384 0.00 0 0.39 17,027 0.88 38,411
TOTAL 1.82 79,196 4.56 198,740 0.00 0 0.48 11 20,909 6.86 298,844
TOTAL 5.63 245,244 7.77 338,463 0.00 0 0.48 20,909 13.88 604,616
PERCENT IMPERVIOUS AREA ON PROPOSED SITE 50.57%
PERCENT INCREASE OF IMPERVIOUS AREA OVER EXISTING SITE 33.03%
P:\2008_000\2008_021 - First Assembly Church\eng\Drainage calculations\Overall pre and post calcs to determine if detention is needed\2008-
021 overall Pre & Post cals for detention on site determination 7-6-09.xls
ALPHA OMEGA GROUP ,PC SIN
Project Name: First Assembly Church
Project Number: 2008.021
Date:2/3/2010
PRE AND POST STORMWATER RU NOFF SUM MARY
DISCHARGE
POINT
C-FACTOR AREA
(AC) 2 YEAR
DISCHARGE
(CFS) 10 YEAR
DISCHARGE
(CFS) 100 YEAR
DISCHARGE
(CFS) PERCENT
INCREASE
(%) DETENTION
REQUIRED
1 PRE-CONSTRUCTION 0.73 5.86 24.6 30.9 41.5
POST-CONSTRUCTION 0.76 5.63 24.5 30.7 41.4 -0.38% NO

2 PRE-CONSTRUCTION 0.46 6.56 17.2 21.6 29.1
POST-CONSTRUCTION 0.59 7.77 26.4 33.1 44.6 53.36% YES

3 PRE-CONSTRUCTION 0.39 0.98 2.2 2.8 3.8
POST-CONSTRUCTION 0.00 0 0.0 0.0 0.0 0% NO
DISCHARGE POINT 2 - PRE AND POST STORMWATER RUNOFF SUMMARY
WITH DRY POND ROUTING
DISCHARGE
POINT
C-FACTOR AREA
(AC) 2 YEAR
DISCHARGE
CFS 10 YEAR
DISCHARGE
CFS 100 YEAR
DISCHARGE
CFS PERCENT
INCREASE
% 10 YR
2 (DRY POND) PRE-CONSTRUCTION 0.52 5.03 15.2 19.0 25.6
POST-CONSTRUCTION 0.63 6.21 22.6 28.4 38.2 48.9706
DRY POND ROUTING 1.8 8.1 18.1 -57.46%

2 (BYPASS) PRE-CONSTRUCTION 0.41 1.56 3.7 4.6 6.2
POST-CONSTRUCTION 0.42 1.56 3.8 4.7 6.4 2.72%

2 (TOTAL) PRE-CONSTRUCTION 6.59 18.9 23.6 31.8
POST-CONSTRUCTION 7.77 5.6 12.8 24.5 -23.14%
OVERALL SITE PRE AND POST STORMWATER RUNOFF SUMMARY
WITH DRY POND ROUTING
DISCHARGE
POINT
C-FACTOR AREA
(AC) 2 YEAR
DISCHARGE
CFS 10 YEAR
DISCHARGE
CFS 100 YEAR
DISCHARGE
CFS PERCENT
INCREASE
% 10 YR
1 PRE-CONSTRUCTION 0.73 5.86 24.6 30.9 41.5
POST-CONSTRUCTION 0.76 5.63 24.5 30.7 41.4 -0.38%

2 DRY POND PRE-CONSTRUCTION 0.52 5.03 15.2 19.0 25.6
POST-CONSTRUCTION 0.63 6.21 1.8 8.1 18.1 -57.46%

2(BYPASS) PRE-CONSTRUCTION 0.41 1.56 3.7 4.6 6.2
POST-CONSTRUCTION 0.42 1.56 3.8 4.7 6.4 2.72%

3 PRE-CONSTRUCTION 0.39 0.98 2.2 2.8 3.8
POST-CONSTRUCTION 0.00 0 0.0 0.0 0.0 0%

TOTAL PRE-CONSTRUCTION 44.0 55.3 74.4
POST-CONSTRUCTION 30.1 43.5 65.9
P:\2009000\2008021 - First Assembly Church\eng\Drainage calculations\Overall pre and post calcs to determine if detention is needed\2008-021 overall Pre &
Post cals for detention on site determination 7-6-09.xls 0
ALPHA OMEGA GROUP,PC ?!
Project Name: First.Assembly Church Date:7/6/2009
Project Number: 2008.021
PRE-CONDITIONS AND POST-DEVELOPMENT STORMWATER RUNOFF DISCHARGE POINT # 1
Existing Conditions: Pre Develo ment Proposed Conditions: Post Develoment
Total Area
Butldin 0.50 acres 21,811 sf
Concrete 0.11 acres 4,717 sf
As halt 3.08 acres 133,950 sf
Gravel 0.02 acres 918 sf
Rubber Chi la area 0.00 acres 0 sf
Grass 2.15 acres 93,867 sf
woods 0.00 acres 0 sf

Total 5.86 acres 255,263 sf
Forest 0.00 acre
Grass 2.15 acre
Total Impervious area 3.71 acres
Total Area
Building 0.50 acres 21,811 sf
Concrete 0.22 acres 9,38-0- sf
Asphalt 3.07 acres 13-3-19-39 sf
Gravel 0.02 acres 918 sf
Rubber Chip la area 0.00 acres 0 sf .
Grass 1.82 acres 79,196 sf
woods 0.00 acres 0 sf

Total 5.63 acres 245,244 sf
Forest 0.00 acre
Grass 1.82 acre
Total impervious area 3.81 acres
Proposed impervious surface area Increase 2,80%
Total Impervious surface area in drainage area 34.95%
Table 2.2. CAN of Ralelah Storrnwater Design Manual
C-Values
C
Building 0.95
Concrete 0.95
Asphalt 0.95
Gravel 0.90
Rubber Mat play area 0.50
Grass 0.35
Woods 0.25

Composite C Values
C
Existing Conditions:
Pre Develo ment 0.73

Proposed Conditions:
Post Develoment 0.76
1 Year Composite C Intensity Area Runoff
Existing Conditions 0.73 4.52 5.86 19.3
Proposed conditions 0.76 4.52 5.63 19.2
% Increase -0.38%
2 Year Composite C Intensity Areal Runoff
Existing Conditions 0.73 5.76 5.86 - -- - 24.6
Proposed conditions 0.76 5.76 5.63, 24.5
% Increase -0.38%
10 Year Composite C Intensity Area Runoff
Existing Conditions 0.73 7.22 5.86 30.9
Proposed conditions 0.76 7.22 5.63 30.7
% increase -0.38%
100 Year Composite C Intensity Area Runoff
Existing Conditions 0.73 9.72 5.86 41.5
Proposed conditions 0.76 9.72 5.63 41.4
% Increase -0.38%
- - N-UNVQaU wnu-uvns scurrrtwater runorT noes not exceed the 10% storm water Increase limit, detention will not be required.
Notes:
Intensities used are from Table 2.3, City of Raleigh, Stnanwater Design Manual,
All Tc=5 min.
Intensity for 1 year storm calculated using I = 104/(t+108).
P:\2008_000\2008_021 - First Assembly Church\eng\Drainage calculations\Overall pre and post sales to determine if detention is needed\2008-021 overall Pre &
Post cals for detention on site detennination 7-6-09.xis
ALPHA OMEGA GROUP,PC / Z
Project Name: First Assembly Church Date:7/6/2009
Project Number: 2008.021
PRE-CONDITIONS AND POST-DEVELOPMENT STORMWATER RUNOFF DISCHARGE POINT # 2
Existing Conditions: Pre Develo ment Proposed Conditions: Post Develoment
Total Area
Building 0.67 acres 29 166 sf
Concrete 0.11 acres 4,852 sf
Asphalt 0.65 acres 28,125 sf
Gravel 0.03 acres 1,422 sf
Rubber Chi la area 0.03 acres 1,422 sf
Grass 3.23 acres 140,685 sf
woods 1.84 acres 80,083 sf

Total
6.56
acres
285,755 Total Area
sf
Forest 1.84 acre
Grass 3.23 acre
Total Impervious area 1.49 acre
Proposed impervious surface area Increase 53.49%
Total impervious surface area In drainage area 51.10%
Table 2.2, City of Raleigh Stonnwater Design Manual
C-Values
C
Building 0.95
Concrete 0.95
Asphalt 0.95
Gravel 0.90
Rubber Mat play area 0.50
Grass 0.35
Woods 0.25

1 Year Composite C Intensity Area Runoff
Existing Conditions 0.46 4.52 6.56 13.5
Proposed conditions 0.59 4.52 7.77 20.7
% Increase 53.36%

Building 0.99 acres 43,092 sf
Concrete 0.20 acres 8 521 sf
Asphalt 1.86 acres 81,156 sf
Gravel 0.16 acres 6,954 sf
Rubber Chip la area 0.00 acres 0 sf
Grass 4.07 acres 177,356 sf
woods 0.49 acres 21 384
J
Total 7.77 acres 338,463 Forest 0.49 acre

Grass 4.07 acre
Total Impervious area 3.21 acres
Composite C Values
C
Existing Conditions:
Pre Develo ment 0.46

Proposed Conditions:
Post Develoment 0.59
2 Year Composite C - Intensity Area Ku' nod
Existing Conditions 0.46 5.76 6.56 17.2
Proposed conditions 0.59 5.76 7.77 26.4
% Increase 53.36%
10 Year Composite C Intensity Area Runoff
Existing Conditions 0.46 7.22 6.56 21.6
Proposed conditions 0.59 7.22 7.77 33.1
% Increase 53.36%
100 Year Composite C Intensity Area Runoff
Existing Conditions 0.46 9.72 6.56 29.1
Proposed conditions 0.59 9.72 7.77 44.6
'0% Increase 53.36%
The proposed conditions stormwater runoff exceeds the 1601, storm water Increase limit, detention will be required.
Notes:
Intensities used are from Table 2.3, City of Raleigh, Stormwater naaign Manual.
All Tc=5 min.
Intensity for 1 year storm calculated using I =104/(t+108).
P:\2008000\2008021 - First Assembly Cburch\eng\Drainage calculations\Overall pre and post calcs to determine if detention is needed\2008-021 overall Pre &
Post cals for detention on site determination 7-6-09.xls
17
ALPHA OMEGA GROUP,PC v?% 4
Project Name: First Assembly Church Date:2/3/2010
Project Number: 2008.021
PRE-CONDITIONS AND POST-DEVELOPMENT STORMWATER RUNOFF DISCHARGE POINT # 3
G.icfinn r-lifinn- tp- rlavalnnmantl Prnnnaart Cnnditinna• tpnst r)PvalnmPntl
Total Area
Building 0.00 acres 0 sf
Concrete 0.00 acres 99 sf
Asphalt 0.00 acres 0 if
Gravel 0.08 acres 3,361 sf
Rubber Chip play area 0.00 acres 0 sf
Grass 0.90 acres 39,229 sf
Dods 0.00 acres 0 sf

Total 0.98 acres 42,689 sf
Total Area
Building 0.00 acres 0 sf
Concrete 0.00 acres 99 sf
Asphalt 0.00 acres 0 sf
Gravel 0.08 acres 3,361 sf
Rubber Chip play area 0.00 acres 0 sf
Grass 0.90 acres 39,229 sf
woods 0.00 acres 0 sf

Total 0.98 acres 42,689 sf
Forest 0.00 acres
Grass 0.90 acres
Total Impervious area 0.08 acres
Forest 0.00 acres
Grass 0.90 acres
Total impervious area 0.08 acres
Proposed impervious surface area increase 0.00%
Total impervious surface area in drainage area 91.89%
Table 2.2. Citv of Raleiah Stormwater Design Manual
C-Values
C
Building 0.95
Concrete 0.95
Asphalt 0.95
Gravel 0.90
Rubber Mat play area 0.50
Grass 0.35
Woods 0.25

Composite C Values
C
Existing Conditions:
Pre Development) 0.39

Proposed Conditions:
Post Develoment 0.39
Frequency (Years)
1 Year Composite C Intensity Area Runoff
Existing Conditions 0.39 4.52 0.98 1.7
Proposed conditions 0.39 4.52 0.98 1.7
% increase 0.00%
2 Year Composite C Intensity Area Runoff
Existing Conditions 0.39 5.76 0.98 2.2
Proposed conditions 0.39 5.76 0.98 2.2
% increase 0.00%
10 Year Composite C Intensity Area Runoff
Existing Conditions 0.39 7.22 0.98 2.8
Proposed conditions 0.39 7.22 0.98 2.8
% increase 0.00%
100 Year Composite C Intensity Area Runoff
Existing Conditions 0.39 9.72 0.98 3.8
Proposed conditions 0.39 9.72 0.98 3.8
% increase 0.00%
I ne proposed conditions stormwater runott does not exceed the 10% storm water increase limit, detention will not be required
Notes:
Intensities used are from Table 2.3, City of Raleigh, Stonmwater Design Manual.
All Tc=5 min.
Intensity for 1 year storm calculated using I = 104/(t+108).
P:\2008_000\2008_021 - First Assembly Church\eng\Drainage calculations\Overall pre and post calcs to determine ifdetention is needed\2008-021 overall Pre & Post
cals for detention on site determination 7-6-09.xls a /52
ALPHA OMEGA GROUP PC
Project Name: First Assembly Church Date:7/6/2009
Project Number: 2008.021
PRE-CONDITIONS AND POST-DEVELOPMENT DRY POND AREAS FOR DISCHARGE POINT # 2
C..ic+Inn P-11fi-a- /Dm navainnmantl Proposed Conditions: (Post Develoment)
Total Area
Building 0.67 acres 29,166 sf
concrete 0.11 acres 4,852 sf
Asphalt 0.65 acres 28125 sf
Gravel 0.03 acres 1,42-2- sf
Rubber Chi la area 0.02 acres 901 sf
Grass 3.55 acres 154,642 sf
woods 0.00 acres 0 sf

Total 5.03 acres 219,108 sf
Total Area
Building 0.99 acres 43,092 sf
Concrete 0.20 acres 8 521 sf
Asphalt 1.59 acres 69 245 sf
Gravel 0.16 acres 6_19-54 sf
Rubber Chi la area 0.02 acres 901 sf .
Grass 3.26 acres 141,796 sf
woods 0.00 acres 0 sf

Total 6.21 acres 270,509 sf
Forest 0.00 acre
Grass 3.55 acres
Total Impervious area 1.48 acres
Forest - 0.00 acre
Grass 3.26 acres
Total Impervious area 2.95 acres
Proposed Impervious surface area Increase 49.91%
Total impervious surface area In drainage area 41.26%
Takla 1!) City of Ralwinh Stnrmwater Desien Manual
C-Values
C
Building 0.95
Concrete 0.95
Asphalt 0.95
Gravel 0.90
Rubber Mat play area 0.50
Gress 0.35
Woods 0.25

Composite C Values
C
Existing Conditions:
Pre Develo ment 0.52

Proposed Conditions:
Post Develoment 0.63
1 Year Composite C Intensity Area Runoff
Existing Conditions 0.52 4.52 5.03 11.9
Proposed conditions 0.63 4.52 6.21 17.8
% Increase 48:97%
2 Year Composite C Intensity Area Runoff
Existing Conditions 0.52 5.76 5.03 15.2
Proposed conditions 0.63 5.76 6.21 22.6
% increase 48.97%
10 Year Composite C Intensity Area Runoff
Existing Conditions 0.52 7.22 5.03 19.0
Proposed conditions 0.63 7.22 6.21 28.4
% Increase 48.97%
100 Year Composite C Intensity Area Runoff
Existing Conditions 0.52 9.72 5.03 25.6
Proposed conditions 0.63 9.72 6.21 38.2
% Increase 48.97%
The proposed conditions stormwater runoff exceeds the 10% storm water Increase limit, detention will be required.
Notes:
Intensities used are from Table 2.3, City of Raleigh, Stnrmwatsr Daaign Manual.
All Tc=5 min.
Intensity for 1 year storm calculated using I = 1041(t+108).
P:\2008000\2008021 - First Assembly Church\eng\Drainage calculations\Overall pre and post calcs to determine if detention is needed\2008-021 overall Pre &
Post cals for detention on site determination 7-6-09.xls
o %2
ALPHA OMEGA GROUP,PC
Project Name: First Assembly Church Date:7/6/2009
Project Number: 2008.021
PRE-CONDITIONS AND POST-DEVELOPMENT AREAS BYPASSING POND FOR DISCHARGE POINT #2
Existing Conditions: Pre Develo meat Proposed Conditions: Post Develoment
Total Area
Bulldin 0.00 acres sf
concrete 0.00 acres sf
As Halt 0.27 acres 1I'm 1 sf
Gravel 0.00 acres sf
Rubber Chi la area 0.00 acres sf
Grass 0.57 acres 24,996 sf
woods 0.71 acres 31,047, sf

Total 1.56 acres 67,954 sf
Forest 0.71 acres
Grass 0.57 acre
Total impervious area 0.27 acres
Total Area
Building 0.00 acres sf
Concrete 0.00 acres sf
Asphalt 0.27 acres 11,911 sf
Gravel 0.00 acres sf
Rubber Chi la area 0.00 acres sf
Grass 0.75 acres 32,577 sf
woods 0.54 acres 2111,466 sf

Total 1.56 acres 67,954 sf
Forest 0.54 acres
Grass 0.75 acre
Total Impervious area 0.27 acres
Proposed impervious surface area Increase 0.00%
Total impervious surface area In drainage area 82,47%
retire 9 9 (tav of Ralwinh Stnanwwtwr nacian Manual
C-Values _
C
Building 0.95
Concrete 0.95
Asphalt 0.95
Gravel 0.90
Rubber Mat play area 0.50
Gress 0.35
Woods 0.25

Composite C Values
C
Existing Conditions:
Pre Develo ment 0.41

Proposed Conditions:
Post Develoment 0.42
1 Year Composite C Intensity Area Runoff
Existing Conditions 0.41 4.52 1.56 2.9
Proposed conditions 0.42 4.52 1.56 3.0
% Increase 2.72%
2 Year Composite C Intensity Area Runoff
Existing Conditions 0.41 5.76 1:56 3.7
Proposed conditions 0.42 5.76 1.56 3.8
% Increase 2.72%
10 Year Composite C Intensity Area Runoff
Existing Conditions 0.41 7.22 1.56 4.6
Proposed conditions 0.42 7.22 1.56 4.7
% Increase 2.72%
100 Year Composite C Intensity Area Runoff
Existing Conditions 0.41 9.72 1.56 6.2
Proposed conditions 0.42 9.72 1.56 6.4
% Increase 2.72%
The proposed conditions stormwater runoff exceeds the 10% storm water increase limit, detention will be required.
Notes:
Intensities used are from Table 2.3, City of Raleigh, Srnrmwwtwr oweign Man uwl.
All Tc=5 min.
Intensity for 1 year storm calculated using I = 104/(t+108).
1
P:\2008_000\2008_021 - First Assembly Church\eng\Drainage calculations\Overall pre and post calcs to determine if detention is needed\2008-021 overall Pre &
Post cals for detention on site determination 7-6-09.xls
ALPHA OMEGA GROUP ,PC 3?

DRY POND CALCULATIONS
12??
Hydrograph Return Period - HyarMydrographs Extension for AutoCADO Civil 3D® 2008 by Autodesk, Inc. v6.052
Hyd. Hydrograph Inflow Peak Outflow (cfs) Hydrograph
i
ti
d
'No. type Hyd(s) escr
p
on
(origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr
1 Rational ------ 9.439 15.53 ------- ------- 19.48 ------- ------- 26.21 Pre construction

3
Rational
------
13.68
22.52
-------
-------
28.23
-------
-------
38.00 /
Post Construction CI )0trr t /o-
5 Reservoir 3 1.504 1.802 ------- ------- 8.138 ------- ------- 18.10 dry pond trap routing
05 46 S, ih c,

Proj. file: first assembly dry pond 11-11-09.gpw Monday, Feb 1, 2010 13 /3Z
H yd rog ra p h Summary Re poAt raflow Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052
Hyd.
No. Hydrograph
type
(origin) Peak
flow
(cfs) Time
interval
(min) Time to
peak
(min) Hyd.
volume
(cuft) Inflow
hyd(s) Maximum
elevation
(ft) Total
strge used
(cuft) Hydrograph
description
1 Rational 9.439 1 5 2,832 ------ ------ ------ Pre construction
3 R
ti
l 13
68 1 5 4
105
------
------
------
Post Construction (Vii.
a
ona . ,
5 Reservoir 1.504 1 9 4,100 3 402.80 3,526 dry pond trap routing
first assembly dry pond 11-11-09.gpw Return Period: 1 Year Monday, Feb 1, 2010 l?Z
6
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCADO Civil 3D® 2008 by Autodesk, Inc. v6.052 Monday, Feb 1, 2010
Hyd. No. 5 ?4m :57,69L. 67VC,1-J-r

dry pond trap routing -
Hydrograph type = Reservoir Peak discharge = 1.504 cfs
= 0
15 h
;
O
Storm frequency = 1 yrs Time to peak .
rs
'W
4
Time interval = 1 min Hyd. volume = 4,100 cuft
Inflow hyd. No. = 3 - Post Construction Max. Elevation = 402.80 ft
Reservoir name = dry pond trap Max. Storage = 3,526 cuft
Storage Indication method used.
dry pond trap routing
Q (cfs) Hyd. No. 5 -- 1 Year
14.00
12.00
10.00
8.00
6.00
4.00
2.00
Q (cfs)
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00 0.00
0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 1.8 2.0
Hyd No. 5 -- Hyd No. 3 IIIILIL[11] Total storage used = 3,526 cuft Time (hrs)
15132
5

Pond Report '
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052 Monday, Feb 1, 2010
Pond No. 3 - dry pond trap
Pond Data
Trapezoid - Bottom L x W = 45.9 x 14.5 ft, Side slope = 3.00:1, Bottom elev. = 400.00 ft, Depth = 5.00 ft
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sgft) Incr. Storage (cult) Total storage (cuft)
0.00 400.00 665 0 0
0.50 400.50 855 379 379
1.00 401.00 1,063 479 858
1.50 401.50 1,289 587 1,446
2.00 402.00 1,534 705 2,151
2.50 402.50 1,796 832 2,982
3.00 403.00 2,076 967 3,949
3.50 403.50 2,374 1,112 5,061
4.00 404.00 2,690 1,265 6,326
4.50 404.50 3,024 1,428 7,754
5.00 405.00 3,376 1,599 9,353
Culvert / Orifice Structures Weir Structures
[A] [B] [C] [PrfRSr] [A] [13] [C] [D]
Rise (in) = 18.00 6.00 0.00 0.00 Crest Len (ft) = 18.67 0.00 0.00 0.00
Span (in) = 18.00 6.00 0.00 0.00 Crest El. (ft) = 403.50 0.00 0.00 0.00
No. Barrels = 1 1 0 0 Weir Coeff. = 2.60 3.33 3.33 3.33
Invert El. (ft) = 400.00 400.00 0.00 0.00 Weir Type = Broad -- --- ---
Length (ft) = 42.00 0.00 0.00 0.00 Multi-Stage = Yes No No No
Slope (%) = 5.57 0.00 0.00 n/a
N-Value = .013 .013 .013 n/a
Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000 (by Wet area)
Multi-Stage = n/a No No No TW Elev. (ft) = 0.00
Note: Culvert/Odflce outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Storage / Discharge Table
Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total
ft cult ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
0.00 0 400.00 0.00 0.00 --- --- 0.00 --- --- --- --- --- 0.000
0.50 379 400.50 0.00 0.47 is --- --- 0.00 --- --- --- --- -- 0.473
1.00 858 401.00 0.00 0.82 is --- --- 0.00 --- --- --- --- --- 0.819
1.50 1,446 401.50 0.00 1.06 is --- --- 0.00 --- --- --- --- --- 1.057
2.00 2,151 402.00 0.00 1.25 is --- --- 0.00 --- --- --- --- --- 1.251
2.50 2,982 402.50 0.00 1.42 is --- --- 0.00 --- -- --- --- --- 1.418
3.00 3,949 403.00 0.00 1.57 is --- --- 0.00 --- --- --- --- --- 1.568
3.50 5,061 403.50 0.00 1.70 is --- --- 0.00 --- --- --- --- --- 1.704
4.00 6,326 404.00 14.71 is 1.83 is --- --- 14.71 s --- --- --- --- -- 16.54
4.50 7,754 404.50 16.39 is 1.95 is --- --- 16.39s --- --- --- -- -- 18.34
5.00 9,353 405.00 17.51 is 2.06 is --- --- 17.51 s --- --- --- -- -- 19.57

Ilo?3Z
H yd rog ra p h Summary Re p oAraflow Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052
Hyd.
No. Hydrograph
type
(origin) Peak
flow
(cfs) Time
interval
(min) Time to
peak
(min) Hyd.
volume
(cuft) Inflow
hyd(s) Maximum
elevation
(ft) Total
strge used
(tuft) Hydrograph
description
1 Rational 15.53 1 5 4,660 ------ ------ ------ Pre construction
3 Rational 22.52 1 5 6,755 ------ ------ ------ Post Construction
5 Reservoir 1.802 1 10 6,750 3 403.90 6,030 dry pond trap routing
first assembly dry pond 11-11-09.gpw Return Period: 2 Year Monday, Feb 1, 2010 17/Z

Hydrograph Report 11
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052 Monday, Feb 1, 2010
Hyd. No. 5
dry pond trap routing
Hydrograph type = Reservoir Peak discharge = 1.802 cfs
Storm frequency = 2 yrs Time to peak = 0.17 hrs
Time interval = 1 min Hyd. volume = 6,750 cuft
Inflow hyd. No. = 3 - Post Construction Max. Elevation = 403.90 ft
Reservoir name = dry pond trap Max. Storage = 6,030 cuft
Storage Indication method used
Q (cfs)
24.00
20.00
16.00
3
12.00
8.00
4.00
v
Q (cfs)
24.00
20.00
16.00
12.00
8.00
4.00
0.00 „ I I -•I- I 0.00
0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 1.8 2.0 2.2 2.3
Hyd No. 5 - Hyd No. 3 U.17iTE Total storage used = 6,030 cuft Time (hrs)
,?3 /3Z
dry pond trap routing
Hyd. No. 5 -- 2 Year
12
Hyd rog ra p h Summary Re poKt raflow Hydrographs Extension for AUtoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052
Hyd.
No. Hydrograph
type
(origin) Peak
flow
(cfs) Time
interval
(min) Time to
peak
(min) Hyd.
volume
(cuft) Inflow
hyd(s) Maximum
elevation
(ft) Total
strge used
(cult) Hydrograph
description
1 Rational 19.48 1 5 5,843 ------ ------ ------ Pre construction
3 Rational 28.23 1 5 8,470 ------ ------ ------ Post Construction
5 Reservoir 8.138 1 9 8,466 3 404.28 7,054 dry pond trap routing
first assembly dry pond 11-11-09.gpw Return Period: 10 Year Monday, Feb 1, 2010 iq /3Z
15
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052 Monday, Feb 1, 2010
Hyd. No. 5
dry pond trap routing
Hydrograph type = Reservoir Peak discharge = 8.138 cfs
Storm frequency = 10 yrs Time to peak = 0.15 hrs
Time interval = 1 min Hyd. volume = 8,466 cuft
Inflow hyd. No. = 3 - Post Construction Max. Elevation = 404.28 ft
Reservoir name = dry pond trap Max. Storage = 7,054 cuft
Storage Indication method used.
Q (cfs)
30.00
25.00
20.00
15.00
10.00
5.00
it
S
Q (cfs)
30.00
25.00
20.00
15.00
10.00
5.00
0.00 " , , , 0.00
0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 1.8
Hyd No. 5 Time (hrs)
- Hyd No. 3 [011 11111] Total storage used = 7,054 cuft
Zo/32
dry pond trap routing
Hyd. No. 5 -- 10 Year
16
H yd rog ra p h Summary Re P O raf low Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052
FHyd.
No. Hydrograph
type
(origin) Peak
flow
(cfs) Time
interval
(min) Time to
peak
(min) Hyd.
volume
(cuft) Inflow
hyd(s) Maximum
elevation
(ft) Total
strge used
(cuft) Hydrograph
description
1 Rational 26.21 1 5 7,864 ------ ------ ------ Pre construction
3 Rational 38.00 1 5 11,400 ------ ----- ------ Post Construction
5 Reservoir 18.10 1 8 11,395 3 404.60 7,975 dry pond trap routing
first assembly dry pond 11-11-09.gpw Return Period: 100 Year Monday, Feb 1, 2010 ?I/3Z
Hydrograph Report
19
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052 Monday, Feb 1, 2010
Hyd. No. 5
dry pond trap routing
Hydrograph type = Reservoir Peak discharge = 18.10 cfs
Storm frequency = 100 yrs Time to peak = 0.13 hrs
Time interval = 1 min Hyd. volume = 11,395 cuft
Inflow hyd. No. = 3 - Post Construction Max. Elevation = 404.60 ft
Reservoir name = dry pond trap Max. Storage = 7,975 cuft
Storage Indication method used
Q (cfs)
40.00
30.00
20.00
10.00
#5
0.00 a, 0.0 0.2
Hyd No. 5
dry pond trap routing
Hyd. No. 5 -- 100 Year

0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7
- Hyd No. 3 [ITT111-M Total storage used = 7,975 cuft
Q (cfs)
40.00
30.00
20.00
10.00
0.00
1.8
Time (hrs)
ZZ /3 7-
Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for AUtoCAD® Civil 3D® 2008 by Autodesk, Inc. v6.052 Monday, Feb 1, 2010
Return
P
i
d Intensity-Duration-Frequency Equation Coefficients (FHA)
er
o
(Yrs) B D E (N/A)
1 79.7413 17.3000 1.0072 --------
2 74.0559 13.3000 0.8788 --------
3 0.0000 0.0000 0.0000 --------
5 83.5112 14.8000 0.8514 --------
10 105.7041 16.8000 0.8710 --------
25 118.9252 17.6000 0.8582 --------
50 137.0265 18.6000 0.8630 --------
100 157.1769 19.6000 0.8692 --------
File name: raleigh.IDF
Intensity = B / (Tc + D)"E
Return
Period Intensity Values (in/hr)
(Yrs) 5 min 10 15 20 25 30 35 40 45 50 55 60
1 3.50 2.85 2.41 2.08 1.84 1.64 1.48 1.35 1.24 1.15 1.07 1.00
2 5.76 4.65 3.92 3.40 3.01 2.70 2.45 2.25 2.08 1.93 1.81 1.70
3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 6.57 5.43 4.64 4.07 3.63 3.28 3.00 2.76 2.57 2.40 2.25 2.12
10 7.22 6.03 5.19 4.57 4.09 3.71 3.40 3.13 2.91 2.72 2.56 2.41
25 8.19 6.90 5.98 5.29 4.75 4.32 3.97 3.67 3.41 3.20 3.01 2.84
50 8.95 7.59 6.60 5.86 5.27 4.80 4.41 4.08 3.81 3.57 3.36 3.17
100 9.71 8.27 7.22 6.42 5.79 5.28 4.86 4.50 4.20 3.93 3.70 3.50
Tc = time in minutes. Values may exceed 60.
Preci . file name: Sample c
Rainfall Precipitation Table (in)
Storm
Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr
SCS 24-hour 0.00 2.20 0.00 3.30 4.25 5.77 6.80 7.95
SCS 6-Hr 0.00 1.80 0.00 0.00 2.60 0.00 0.00 4.00
Huff-1st 0.00 1.55 0.00 2.75 4.00 5.38 6.50 8.00
Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Custom 3.50 5.76 0.00 6.58 7.22 8.19 8.96 9.72
2 313Z
Hyd raf l ow OF Curves
OF file: raleigh.IDF
Intensity (in/hr)
00 100
Y
14
14.00 r
.
-
12
00 12
00
. .
.
10
.00 10.00 25-Yr

8
00
. 8.00 10-Yr
6
00
. S 6.00 5-Yr

4
00 sa
. 4.00 2-Yr

2
00
. 2.00 1-Yr
0
00
.
0.00
0 5 10 15 20 25 30 35 40 45 50 55 60
Time (min)
ZA- 3 Z
H yd raflowH ydrographsExtension
SPLITTER BOX AND LEVEL SPREADER HYDRAULIC GRADE
LINE CALCULATIONS
zs/3z
PROJECT NO.U606-dZ1 /S?HEE45? OF Z
I' PROJECT NAME ,('TS?/??31• Y
PREPARED BY ?Zc?Gc DATE
ALPHA & OMEGA GROUP CHECKED BY
CIVIL & STRUCTURAL ENGINEERS
DATE
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PROJECT NO. Z W-F-Q2 l SHEETS Q OF 32-
PROJECT NAME 1 I KsT ASS 6W 6 V y
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PREPARED BY Z161.5 LO DATE
CHECKED BY DATE
Reference:
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PROJECT NO. Z06& - y Zr SHEET S OF 3 Z
PROJECT NAME l- JA r .4-SeAlO L y
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PREPARED BY T DATE ?' ! ! O
CHECKED BY DATE
Reference:
yP,?s s P? P? Disc ?????? To Misr. s? ??
P/ PS Dib.. = 2A-(
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P I PE- CA-pA c rr Y (FYI- Ftc-o)
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?>YPass D Sct- Ap F- Fl?.om 5Puirrse MaA\bLE-
CST/L

ZSd ,/3 a
' FIGURE 20
RELATIVE VELOCITY AND FLOW IN
CIRCULAR PIPE FOR ANY DEPTH OF FLOW
m .
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MOIJ 30 H1d30
/VC ea>5"001
Appendices
NEW YORK DOT DISSIPATOR METHOD
FOR USE IN DEFINED CHANNELS
(Source: "Bank and channel lining procedures", New York Department of
Transportation, Division of Design and Construction, 1971.)
NOTE: To use the following chart you must know:
(1) Q full capacity
(2) Qi0
(3) V full
(4) V 10
where Q = discharge in efs and V = Velocity in FPS.
ESTIMATION OF STONE SIZE AND DIMENSIONS FOR
CULVERT APRONS
Step 1) Compute flow velocity V at culvert or paved channel outlet.
Step 2) For pipe culverts Do is diameter.
For pipe arch, arch and box culverts, and paved channel outlets,
D0 = A0 where A. = cross-sectional area of flow at outlet.
For multiple culverts, use D. = 1.25 x D. of single culvert.
Step 3) For apron grades of 10% or steeper, use recommendations
For next higher zone. (Zones 1 through 6).

IZ'?
Rev. 12/93
8.06.5
C
0' 5' 10' is, 20' 25'
DIAMETER (Ft.)
Figure 8.06c
'L,$',; )3 Z.
yea ? ? 5c^D 1 M ? ?? T?!'7'? ®?,

LENGTH OF APRON
W
Z
N
APRON MATERIAL TO PROTECT
CULVERT

L1 TO PREVENT SCOUR
HOLE USE L2 ALWAYS
L2
1 STONE FILLING (FINE) CL. A 3 X Do 4 x D.
2 STONE FILLING (LIGHT) CL. B 3 X Do 6 x D.
3 STONE FILLING (MEDIUM) L. 1 4 X Do 8 x D
4 STONE FILLING (HEAVY) CL. 1 4 X Do 8 x D.
5 STONE FILLING (HEAVY) CL. 2 5 X Do 10 x D.
6 STONE FILLING (HEAVY) CL. 2 6 X Do 10 x D.
7 SPECIAL STUDY REQUIRED (ENERGY DISSIPATORS, STILLING
BASIN OR LARGER SIZE STONE).
Figure 8.06d
Width = 3 times pipe dia. (min.) 2 CZ/ ;? ' l'/h
DETERMINATION OF STONE SIZES FOR DUMPED STONE
CHANNEL LININGS AND REVETMENTS
Step 1. Use figure 8.06.b.3 to determine maximum stone size (e.g. for 12
Fps = 20" or 550 lbs.
Step 2. Use figure 8.06.b.4 to determine acceptable size range for stone
(for 12 FPS it is 125-500 lbs. for 75% of stone, and the maximum
and minimum range in weight should be 25-500 lbs.).
NOTE: In determining channel velocities for stone linings and revetment,
use the following coefficients of roughness:
Diameter Manning's Min. thickness
(inches) "n" of lining (inches)
Fine 3 0.031 9 12
Light 6 0.035 12 18
Medium 13 0.040 18 24
Heavy 23 0.044 30 36
(Channels) (Dissapators)
$ (2 ") = I ?o ? r? ??rt
8.06.6 Rev. 12/93
Z5 /3
NCDENR Stormwater BMP Manual Chapter Revised 09-28-07
Figure 5-2
Flow splitter in Manhole
(Minnesota Urban Small Sites BMP Manual, 2001)
to mass conveyance
system or detention pony!
Type 2 C.B.
A
t-
inflow
PLAN VIEW
NTS
round solid lid -,

Handhold and steps or .
ladder access (provide
ladders to both sides of
wall if weir > 36" high),
WO design water
surface elevation
inflow I=> F
d" min. thickness - -?
reinforced concrete SECTION A-A
baffle wall or other
suitable material NTS
Note: The water quality discharge pipe may require
an orffime plate be installed on the outlet to control
the height of the design water surface (weir height).
The design water surface should be set to provide
a rninimun headwater/diarneter ratio of 2.D on the
outlet pipe. -----
i ?
? F
F
71
'einforced baffle wall grouted
o M.H. structure (both ends)
A to WQ facility
4' min.
or provide separate
access to either aide
of baffle wail
to water quality facify
2' min.
bypass. Pipe
Common BW Design Elements 5-6 July 2007
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