20021169 Ver 5_401 Application_20110729

WITHERS RAVENEI_
ENGINEERS I PLANNERS I SURVEYORS
111 MacKenan Drive
CARY, NORTH CAROLINA, 27511
[phone]
FAX [phone]
TO: NCDENR - DWQ
LETTER OF 7 MH5 DOOQ1
DATE 07-29-11 JOB NO. 02100061.00
ATTENTION Annette Lucas
PHONE #
RE: Highcroft Village
WE ARE SENDING YOU Attached via
? Shop Drawings ? Prints ? Plans
? Copy of Letter ? Change order ? Diskette
_ the following items:
? Samples ? Specifications
COPIES DATE NO. DESCRIPTION
1 Highcroft Village Phase 4
1 Highcroft Village Phase 5
1 CD containin df files of Phase 4 and Phase 5
no

DF-PAP
i wetEandr s 8??r,wate(_ tee Bra???l
THESE ARE TRANSMITTED as checked below:
? For approval ? Approved as submitted ? Resubmit copies for approval
? For your use ? Approved as noted ? Submit copies for distribution
? As requested ? Returned for corrections ? Return corrected prints
? For review and comment ?
? FOR BIDS DUE 20 ? PRINTS RETURNED AFTER LOAN TO US
REMARKS: Annette, enclosed are the complete sets of plans you requested. Please let me know if
you have any questions. Thanks
COPY TO: SIGNED: Mike Schneider
if enclosures are not as noted, kindly notify us at once.
,ran
L
Office Use Only:
Corps action ID no.
DWQ project no.
Form Version 1.4 January 2009
Pre-Construction Notification (PCN) Form
A. Applicant Information
1. Processing
1 a. Type(s) of approval sought from the Corps: sA / ? Section 404 Permit ? Section 10 Permit
1b. Specify Nationwide Permit (NWP) number: o l k or General Permit (GP) number:
1c. Has the NWP or GP number been verified by the Corps? r-f/ A ? Yes ? No
1 d. Type(s) of approval sought from the DWQ (check all that apply):
? 401 Water Quality Certification - Regular ? Non-404 Jurisdictional General Permit
? 401 Water Quality Certification - Express N 1 [J Riparian Buffer Authorization
1 e. Is this notification solely for the record
because written approval is not required?
!/ A
r- For the record only for DWQ
401 Certification:
E] Yes 'J E] No For the record only for Corps Permit:

? Yeses A

? No
1f. Is payment into a mitigation bank or in-lieu fee program proposed for
mitigation of impacts? If so, attach the acceptance letter from mitigation bank
or in-lieu fee program. ? (A
? Yes ? No
1 g. Is the project located in any of NC's twenty coastal counties. If yes, answer 1 h
below. ? Yes V-No
1 h. Is the project located within a NC DCM Area of Environmental Concern (AEC)? ? Yes ? No
2. Project Information
2a. Name of project: k1 / 67W c Al PT l./I Zkl,
2b. County: In/A KE'
2c. Nearest municipality / town: C.A
I?`I
2d. Subdivision name: I C?0P- I L("tULs-- to L_
2e. NCDOT only, T.I.P. or state project no: N!d
3. Owner Information
3a. Name(s) on Recorded Deed: N?G?? GRF? ??sS ??
3b. Deed Book and Page No.
3c. Responsible Party (for LLC if
applicable):
3d. Street address:
3e. City, state, zip: f',gP_ ,J ce Z? Sl3
3f. Telephone no.: 0 a v
3g. Fax no.:
3h. Email address:
Page 1 of 10
PCN Form - Version 1.4 January 2009
4. Applicant Information (if different from owner)
4a. Applicant is: ? Agent ? Other, specify:
4b. Name:
4c. Business name
(if applicable):
4d. Street address:
4e. City, state, zip: 0
N

4f. Telephone no.: 1
I
N
4g. Fax no.:
4h. Email address:
5. Agent/Consultant Information (if applicable)
5a. Name:
5b. Business name
(if applicable):
5c. Street address:
5d. City, state, zip:
5e. Telephone no.:
5f. Fax no.:
5g. Email address:
Page 2 of 10
B. Project Information and Prior Project History
1. Property Identification
1 a. Property identification no. (tax PIN or parcel ID): b --7 k -W2-
1 b. Site coordinates (in decimal degrees): Latitude: 3 5, ?o SZo 42 a K Longitude:
1 c. Property size: --71 - I? ?-i acres
2. Surface Waters
2a. Name of nearest body of water to proposed project:
L?
rj -f-H
2b. Water Quality Classification of nearest receiving water: WS SV
2c. River basin: 6
3. Project Description
3a. Describe the existing conditions on the site and the general land use in the vicinity of the project at the time of this
application:
3b. List the total estimated acreage of all existing wetlands on the property: '1 1,N-
3c. List the total estimated linear feet of all existing streams (intermittent and perennial) on the property: u(,?
3d. Explain the purpose of the proposed project:
?--C- -:,? 10 5UbQt rJ?S[oJ
3e. Describe the overall project in detail, including the type of equipment to be used:
N(Ps
4. Jurisdictional Determinations
4a. Have jurisdictional wetland or stream determinations by the
Corps or State been requested or obtained for this property /
ro'ect (including all prior phases) in the past? ? Yes ? No ? Unknown
^
Comments: A( Pk-
4b. If the Corps made the jurisdictional determination, what type
of determination was made? ? Preliminary ? Final
4c. If yes, who delineated the jurisdictional areas?
Name (if known): Agency/Consultant Com any:
Other:
4d. If yes, list the dates of the Corps jurisdictional determinations or State determinations an attach documentation.
5. Project History
5a. Have permits or certifications been requested or obtained for
this project (including all prior phases) in the past? ? Yes ? No ? Unknown
5b. If yes, explain in detail according to "help file" instructions.
I
6. Future Project Plans
6a. Is this a phased project? ? Yes ? No
6b. If yes, explain.
Page 3 of 10
PCN Form - Version 1.4 January 2009
C. Proposed Impacts Inventory
1. Impacts Summary
1a. Which sections were completed below for your project (check all that apply):
? Wetlands ? Streams -tributaries ? Puffers ? Open Waters ? Pond Construction
2. Wetland Impacts
If there are wetland impacts proposed on the site, then comp to this question for each wetland area impacted.
2a.
Wetland impact
number
Permanent (P) or
Tem ora T 2b.
Type of impact 2c.
Type of
wetland 2d.
Forested 2e.
Type of jurisdiction
Corps (404,10) or
DWQ (401, other) 2f.
Area of
impact
(acres)
W1 - Choose one Choose one Yes/No
W2 - Choose one Choose one Yes/No -
W3 - Choose one Choose one Yes/No
W4 - Choose one Choose one Yes/No
W5 - Choose one Choose one Yes/No -
W6 - Choose one Choose one Yes/No
2g. Total Wetland Impacts:
2h. Comments:
3. Stream Impacts
If there are perennial or intermittent stream impacts (includin temporary impacts) proposed on the site, then complete this
question for all stream sites impacted.
3a.
Stream impact
number
Permanent (P) or
Temporary (T) 3b.
Type of impact 3c.
Stream name 3d.
Perennial (PER) or
intermittent (INT)? 3e.
Type of
jurisdiction 3f.
Average
stream
width
(feet) 3g.
Impact
length
(linear
feet)
S1 - Choose one
S2 - Choose one
S3 - Choose one -
S4 - Choose one -
S5 - Choose one
S6 - Choose one -
3h. Total stream and tributary impacts
3i. Comments:
Page 4 of 10
PCN Form - Version 1.4 January 2009
4. Open Water Impacts ?/?N-
If there are proposed impacts to lakes, ponds, estuaries, tributaries, sounds, the Atlantic Ocean, or any other open water of
the U.S. then individual) list all open water impacts below.
4a. 4b. 4c 4d. 4e.
Open water Name of waterbody
impact number (if applicable) Type of impact Waterbody Area of impact (acres)
Permanent (P) or type
Temporary T
01 Choose one Choose
02 Ch se one Choose
03 - Cho se one Choose
04 - Ch ose one Choose
4f. Total open water impacts
4g. Comments:
5. Pond or Lake Construction
If pond or lake construction proposed, then complete the art below.
5a. 5b. 5c. I 5d. 5e.
Pond ID number Proposed use or Wetland I pacts (acres) Stream Impacts (feet) Upland
purpose of pond (acres)
Flooded Filled Excavated Flooded Filled Excavated
P1 Choose one
P2 Choose one
5f. Total:
5g. Comments:
5h. Is a dam high hazard permit required? ? Y ? No If yes, permit ID no:
5i. Expected pond surface area (acres):
5j. Size of pond watershed (acres):
5k. Method of construction:
6. Buffer Impacts (for DWQ)
If project will impact a protected riparian buffer, then complete the chart below. If yes, then individually list all buffer impacts
below. If an impacts require mitigation, then you MUST fill out Section D of this form.
6a. Project is in which protected basin? ? Neuse ? Tar-Pamlico ? Catawba ? Randleman 'E?-Other. CA1 p-
6b. 6c. 6d. 6e. 6f. 6g.
Buffer Impact Reason for impact Stream name Buffer Zone Zone Z^'?
number - mitigation impact impact imp
Permanent (P) or required? (square (square
Temporary T feet feet
B1 P p
0) ?2- <1T 17? 19"\'-t1?_ tZ s' q ec9L Yes/No ?11t - 2,$101. 1,162
B2 - P ?dAO CR0551N(n Yes/No 1\ $Ilk 5,6(07 10,331
B3 Yes/No it
--
17,$loI
B4 -
B5 -
B6 -
6i. Comments:
Yes/No
Yes/No
Yes/No
6h. Total Buffer Impacts:
g-7 ( 1',15 2,`1 Z°I,960
Page 5 of 10
D. Impact Justification and Mitigation
1. Avoidance and Minimization
1 a. Specifically describe measures taken to avoid or minimi a the proposed impacts in designing project.
1b. Specifically describe measures taken to avoid or minimiz the proposed impacts through construction techniques.
2. Com ensato Mitigation for Impacts to Waters oft a U.S. or Waters of the State
2a. Does the project require Compensatory Mitigation for
impacts to Waters of the U.S. or Waters of the State? ? Yes ? No
2b. If yes, mitigation is required by (check all that apply): ? DWQ ? Corps

2c. If yes, which mitigation option will be used for this
project?

pro ? Mitigation bank

El Payment to in-lieu fee program

? Permittee Responsible Mitigation
3. Complete if Using a Mitigation Bank
3a. Name of Mitigation Bank:

3b. Credits Purchased (attach receipt and letter) Type: C
Type: C
Type: oose one
oose one
oose one Quantity:
Quantity:
Quantity:
3c. Comments:
4. Complete if Makin a Payment to In-lieu Fee Program'
4a. Approval letter from in-lieu fee program is attached. ? Yes
4b. Stream mitigation requested: linear feet
4c. If using stream mitigation, stream temperature: Choose one
4d. Buffer mitigation requested (DWQ only): square feet
4e. Riparian wetland mitigation requested: acres
4f. Non-riparian wetland mitigation requested: acres
4g. Coastal (tidal) wetland mitigation requested: acres
4h. Comments:
6
5. Complete if Using a Permittee Responsible Mitigation Ian
5a. If using a permittee responsible mitigation plan, provide a escriptton of the proposed mitigation plan.
Page 6 of 10
PCN Form - Version 1.4 January 2009
6. Buffer Mitigation (State Regulated Riparian Buffer Rules) - required by DWQ
6a. Will the project result in an impact within a protected riparian buffer that requires ? Yes ? No
buffer mitigation? ref
? r
6b. If yes, then identify the square feet of impact to each zone of the riparian buffer that requires mitigation. Calculate the
amount of mitigation required.
6c. 6d. 6e.
Zone Reason for impact Total impact Multiplier Required mitigation
(square feet) (square feet)
Zone 1 3 (2 for Catawba)
Zone 2 1.5
6f. Total buffer itigation required:
6g. If buffer mitigation is required, discuss what type of mitigatio is proposed (e.g., payment to private mitigation bank,
permittee responsible riparian buffer restoration, payment in o an approved in-lieu fee fund).
6h. Comments:
Page 7 of 10
q N,
E. Stormwater Management and Diffuse Flow Plan (required by DWQ)
1. Diffuse Flow Plan
1a. Does the project include or is it adjacent to protected riparian buffers identified
within one of the NC Riparian Buffer Protection Rules? ? Yes ? No
1 b. If yes, then is a diffuse flow plan included? If no, explain why.
? Yes ? No
2. Stormwater Management Plan
2a. What is the overall percent imperviousness of this project? %
2b. Does this project require a Stormwater Management Plan? ? Yes ? No
2c. If this project DOES NOT require a Stormwater Managemen Plan, explain why:
2d. If this project DOES require a Stormwater Management Pla , then provide a brief, narrative description of the plan:
2e. Who will be responsible for the review of the Stormwater Ma agement Plan?
3. Certified Local Government Stormwater Review
3a. In which local overnment's jurisdiction is this project?

3b. Which of the following locally-implemented stormwater mana ement programs
apply (check all that apply): ? Phase II
? NSW
? USMP
? Water Supply Watershed
? Other:
3c. Has the approved Stormwater Management Plan with proof f approval been
attached? []Yes ? No
4. DWQ Stormwater Program Review

4a. Which of the following state-implemented stormwater manag meat programs apply
(check all that apply): []Coastal counties
?HQW
?ORW
[]Session Law 2006-246
? Other:
4b. Has the approved Stormwater Management Plan with proof o
attached? approval been ? Yes ? No
5. DWQ 401 Unit Stormwater Review
5a. Does the Stormwater Management Plan meet the appropriate equirements? ? Yes ? No
5b. Have all of the 401 Unit submittal requirements been met? I ? Yes ? No
\'T
Page 8 of 10
PCN Form - Version 1.4 January 2009

F. Supplementary Information
1. Environmental Documentation (DWQ Requirement)
1 a. Does the project involve an expenditure of public (federal/stat /local) funds or the ? Yes ? No
use of public (federal/state) land?
1 b. If you answered "yes" to the above, does the project require p eparation of an
environmental document pursuant to the requirements of the ational or State ? Yes ? No
(North Carolina) Environmental Policy Act (NEPA/SEPA)?
1 c. If you answered "yes" to the above, has the document review been finalized by the
State Clearing House? (If so, attach a copy of the NEPA or EPA final approval
letter.) ? Yes ? No
Comments:
2. Violations (DWQ Requirement)
2a. Is the site in violation of DWQ Wetland Rules (15A NCAC 2H 500), Isolated
Wetland Rules (15A NCAC 2H .1300), DWQ Surface Water o Wetland Standards, ?Yes ? No
or Riparian Buffer Rules (15A NCAC 2B .0200)?
2b. Is this an after-the-fact permit application? ?Yes ? No
2c. If you answered "yes" to one or both of the above questions, pr vide an explanation of the violation(s):
3. Cumulative Impacts (DWQ Requirement)
3a. Will this project (based on past and reasonably anticipated future impacts) result in ?Yes ? No
additional development, which could impact nearby downstrea water quality?
3b. If you answered "yes" to the above, submit a qualitative or qua titative cumulative impact analysis in accordance with the
most recent DWQ policy. If you answered "no," provide a short arrative description.
4. Sewage Disposal (DWQ Requirement)
4a. Clearly detail the ultimate treatment methods and disposition (no -discharge or discharge) of wastewater generated from
the proposed project, or available capacity of the subject facility.

Page 9 of 10
PCN Form - Version 1.4 January 2009

5. Endangered Species and Designated Critical Habitat (Corps Requirement)
5a. Will this project occur in or near an area with federally p otected species or
habitat? ? Yes ? No
5b. Have you checked with the USFWS concerning Endan ered Species Act
impacts? ? Yes ? No
5c. If yes, indicate the USFWS Field Office you have conta ted. -
5d. What data sources did you use to determine whether you site would impact Endangered Species or Designated Critical
Habitat?
6. Essential Fish Habitat (Corps Requirement)
6a. Will this project occur in or near an area designated as essent I fish habitat? ? Yes ? No
6b. What data sources did you use to determine whether your site would impact Essential Fish Habitat?
7. Historic or Prehistoric Cultural Resources (Corps Requir1I ent)
7a. Will this project occur in or near an area that the state, federa or tribal
governments have designated as having historic or cultural p'eservation
status (e.g., National Historic Trust designation or properties, ignificant in
North Carolina history and archaeology)?
? Yes ? No
7b. What data sources did you use to determine whether your s e would impact historic or archeological resources?
8. Flood Zone Designation (Corps Requirement)
8a. Will this project occur in a FEMA-designated 100-year flood lain? ? Yes ? No
8b. If yes, explain how project meets FEMA requirements:
i
8c. What source(s) did you use to make the floodplain determinat n?

Applicant/Agent's Printed Name Applican Agent's Signature
(Agent's signature is valid only if an authorization
letter from the applicant is provided.) Date
Page 10 of 10
WITHERS &- RAVENEL
STORMWATER MANAGEMENT
REPORT
Highcroft Village - Phase IV
Formerly Highcroft Village Phase II
Cary, North Carolina
Prepared For:
IMPACT PROPERTIES GROUP
113 Triangle Trade Drive
Cary, North Carolina, 27513
Attn: Colen E. Davidson, Jr.
Prepared By:
WITHERS & RAVENEL, INC
111 MacKenan Drive
Cary, North Carolina 27511
July 2010
W&R Project No. 2osooo6l
GARoz ' .
Alwyn V. Smith III, PE
HIGHCROFT VILLAGE - PHASE IV
STORMWATER MANAGEMENT REPORT
CARY, NORTH CAROLINA
INTRODUCTION
Phase IV of Highcroft Village is a proposed 115-lot, single-family residential development located in
Cary, NC, on Green Hope School Rd west of NC-55. This phase was formerly submitted to the Town of
Cary in March, 2ooS as Highcroft Village Phase II. The site lies within the Cape Fear River basin and
is primarily wooded. The site naturally drains to the north and west and is bordered to the north by a
Town of Cary buffered stream channel.
The purpose of this study is to document pre- and post-development peak stormwater runoff flows
for the 1-year and 1o-year design storm events for the proposed residential development. The goal is
to match the pre-development peak for the proposed development at the site during the 1-year
storm and meet Town of Cary nitrogen-loading rate requirements. Two wet ponds are proposed to
attenuate the 1-year storm and reduce the nitrogen-loading rate from the site. As the peak flows for
the 1-, 2-, 5-,10-, and loo-year storms are less than the pre-development peaks, the current
stormwater management plan meets Town of Cary stormwater detention requirements.

Highcroft Village Phase IV W&R Project 2oiooo6i
Stormwater Management Report July 2011
Figure 1. Highcroft Village Phase IV Boundary
HIGHCROFT VILLAGE - PHASE IV
STORMWATER MANAGEMENT REPORT
CARY, NORTH CAROLINA
METHODOLOGY
The stormwater study was conducted using the natural drainage features as depicted by Wake
County LIDAR topography (i-ft contours) and existing field survey data. Proposed drainage areas
were based on field survey data and proposed development within the drainage areas.
The scope of work included the following analyses:
Hydrology
? Simulation of the 1-year, io-year and loo-year rainfall events for the Cary area
? Formulation of the 1-year, to-year and loo-year flood hydrographs for the pre- and post-
development drainage areas
Hydraulic
? Routing the i-year, io-year and loo-year flood hydrographs for pre-development runoff
from the site.
? Routing the i-year, 1o-year and loo-year flood hydrographs for post-development runoff
through the proposed ponds.
The results of the hydrology calculations are used in the hydraulic analyses. The hydraulic design
requires the development of a stage-storage and stage-discharge function for the proposed wet
ponds. The rainfall/runoff hydrographs, stage-storage and stage-discharge functions have been
compiled to create a routing computer simulation model using Haestad Methods PondPack v1o.o
software. This PondPack model was then used to assess the peak water surface elevations for the
design rainfall events. The PondPack modeling results are provided in the appendix of this report.
HYDROLOGY
The cumulative rainfall curve for the 1-year storm event in the Cary area was developed using the
SCS Type II, 24-hour distribution and the 1o-year and ioo-year curves were generated using 24-hour
NOAA Atlas 14 rainfall data from Raleigh-Durham International Airport. Cumulative runoff curves
were determined using the SCS CN Method. This method requires three basic parameters: a curve
number (CN), time of concentration (Q, and drainage area. The 1, 1o, and loo-year runoff
hydrographs were then developed using the SCS unit hydrograph method.
Curve numbers were based on soil type and land use. Soil types were delineated from the Soil
Survey of Wake County, North Carolina (November 1970). Land use for existing conditions was based
on 2004 Wake County orthophotos. Post development land use is based on the proposed site plan.
The curve numbers used in this study are included in the appendix of this report.
Times of concentration were calculated using methods described in the SCS publication "Urban
Hydrology for Small Watersheds, TR-55" and based on lidar and field survey data. The pre-
development time of concentration was calculated using the Kirpich equation. The pre-development
time of concentration calculation is included in the appendix of this report. The post-development
times of concentration were calculated based on flow time through piped drainage systems and/or
small areas of sheet and shallow concentrated flow. These times of concentration were calculated
to be less than or approximately equal to 5 minutes. Therefore the PondPack v1o.o lower limit of 5
minutes was used for all post-development drainage areas.
Highcroft Village Phase IV W&R Project 2oiooo6i
Stormwater Management Report July 2011
HIGHCROFT VILLAGE - PHASE IV
STORMWATER MANAGEMENT REPORT
CARY, NORTH CAROLINA
HYDRAULICS
Computer simulated reservoir routing of the 1-year, so-year and loo-year design storms utilized
stage-storage and stage-discharge functions. A stage-storage function was derived from the
proposed grading of each stormwater pond. A non-linear regression relation for surface area versus
elevation was also derived for each basin. This relation estimated the incremental volume to the
stage or elevation of the pond. Stage-discharge functions were developed to size the proposed
outlet structures for the impoundments.
CONCLUSIONS
Based on the routing study, the proposed ponds provide sufficient volume to attenuate the 1-year
storm, pass the loo-year storm, and reduce nitrogen-loading rates per Town requirements.
Table 1. BMP 1 Attenuation Summary

Storm Event Pre-Development
Outflow Post-Development
Outflow R-40
Outflow
1-Year 12.3 cfs 6.4 cfs 17.8 cfs
2-Year 16.9 cfs 11.6 cfs 23.4 cfs
5-Year 23.6 cfs 22.4 cfs 30.4 cfs
so-Year 28.8 cfs 23.2 cfs 35.64 cfs
Table 1. BMP 2 Attenuation Summary

Storm Event Pre-Development
Outflow Post-Development
Outflow R-40
Outflow
1-Year 14.8 cfs 7.9 cfs 21.3 cfs
2-Year 20.2 cfs 13.7 cfs 27.9 cfs
5-Year 28.2 cfs 24.4 cfs 36.3 cfs
so-Year 34.5 cfs 35.4 cfs 42.6 cfs
Table 1. Bypass Summary

Storm Event Pre-Development
Outflow Post-Development
Outflow R-40
Outflow
1-Year 22.5 cfs 26.7 cfs 32.6 cfs
2-Year 3o.8 cfs 35.8 cfs 42.6 cfs
5-Year 43.1 cfs 48.4 cfs 55.5 cfs
so-Year 52.7 cfs 58.o cfs 65.o cfs
Highcroft Village Phase IV W&R Project 2oiooo6i
Stormwater Management Report July 2011
HIGHCROFT VILLAGE - PHASE IV
STORMWATER MANAGEMENT REPORT
CARY, NORTH CAROLINA
STORMWATER ATTENUATION AND TREATMENT SUMMARY
PROPOSED WET POND #1
• 2" drawdown orifice @ 353.00
• 4' wide weir t7a 355.00
• 5' x 5' slab top inlet box, crest t7a 356.oo
• 18" RCP Outlet Barrel @ 350.00 (Upstream) and 345.00 (Downstream)
• Top of Dam = 36o.oo
Table 2. Wet Pond #1 Operational Summary

Storm Event Peak Water
Surface Elevation
Freeboard
QRS?k Outflow
1-Year 355.66 4.34 ft 6.40 cfs
1o-Year 356.72 3.28 ft 23.16 cfs
loo-Year 357.70 2.30 ft 24.24 cfs
PROPOSED WET POND #2
• 2" drawdown orifice @ 323.00
• 4' wide weir @ 325.00
• 5' x 5' slab top inlet box, crest t7a 326.5o
• 3o" RCP Outlet Barrel @ 320.00 (Upstream) and 319.00 (Downstream)
• Top of Dam = 330.00
Table 3. Wet Pond #2 Operational Summary

Storm Event Peak Water
Surface Elevation
Freeboard
Q Outflow
1-Year 325.77 4.23 ft 7.91 cfs
10-Year 326.81 3.19 ft 35.35 cfs
loo-Year 327.12 2.88 ft 53.92 cfs
Highcroft Village Phase IV W&R Project 20iooo6i
Stormwater Management Report July 2011
PONDPACK OUTPUT
CALCULATIONS
Highcroft Village Phase IV W&R Project 2olooo6l
Stormwater Management Report July 2011
Job File: K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\HIGHCROFT IV-
Rain Dir: K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\
JOB TITLE
Project Date: 12/5/2007
Project Engineer:
Project Title: Highcroft Wet Ponds
Project Comments:
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Table of Contents
'T'able of Contents
i
* +r.e++*rr.a.x*?*awxr MASTER SUMMARY
Watershed....... Master Network Summary ............. 1.01
...a=<+r++x**>+x++ DESIGN STORMS SUMMARY
RDU NOAA 14 Desi Design Storms ...................... 2.01
RDU NOAA 14 Desi 2
Design Storms ...................... 2.02
+xxx*+xxx+++x*.+*x+r*<* TC CALCULATIONS +'+*r++t+*+*w+++**krr
PRE - AREA 1...
PRE - AREA 2....
R-40 AREA 1.....
R-40 AREA 2.....
TO BMP 1........
TO BMP 2........
UNTREATED.......
UNTREATED - PRE
UNTREATED R-40..
........................... 3.01
........................... 3.03
........................... 3.05
........................... 3.07
........................... 3.09
........................... 3.11
........................... 3.13
........................... 3.15
........................... 3.17
Tc'Calcs
Tc Calcs
Tc Calcs
Tc Calcs
Tc Calcs
Tc Calcs
Tc Calcs
Tc Calcs
Tc Calcs
v*x*+r+w+awv?rttW*r•N CN CALCULATIONS ***xxx<x+x*++x+xx+x+a
PRE - AREA 1... Runoff CN-Area ..................... 4.01
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Table of Contents
ii
Table of Contents (continued)
PRE - AREA 2....
R-40 AREA 1.....
R-40 AREA 2.....
TO BMP 1........
TO BMP 2........
UNTREATED.......
UNTREATED - PRE
UNTREATED R-40..
Runoff CN-Area
Runoff CN-Area
Runoff CN-Area
Runoff CN-Area
Runoff CN-Area
Runoff CN-Area
Runoff CN-Area
Runoff CN-Area
..................... 4.02
..................... 4.03
..................... 4.04
..................... 4.05
..................... 4.06
..................... 4.07
..................... 4.08
..................... 4.09
********************** POND VOLUMES ***********************
POND 1.......... Vol: Elev-Area ..................... 5.01
POND 2.......... Vol: Elev-Area ..................... 5.02
******************** OUTLET STRUCTURES *********************
Outlet 1........ Outlet Input Data .................. 6.01
Composite Rating Curve ............. 6.04
Outlet 2........ Outlet Input Data .................. 6.06
Composite Rating Curve ............. 6.09
SIN:
Bentley PondPack (10.00.027.00)
5:00 PM
Bentley Systems, Inc.
5/19/2011
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
MASTER DESIGN STORM SUMMARY
Network Storm Collection: RDU NOAA 14 Desi
Total
Depth
Return Event in
2 3.4400
5 4.3000
10 4.9800
100 7.3700
1 3.0000
Rainfall
Type
----------------
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Synthetic Curve
RNF ID
RDU NOAA 2yr
RDU NOAA 5yr
RDU NOAA l0yr
RDU NOAA 100yr
TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Return HYG Vol
Node ID Type Event ac-ft Trun
*OUT POST JCT 2 5.741 R
*OUT POST JCT 5 7.950 R
*OUT POST JCT 10 9.751 R
*OUT POST JCT 100 16.299 R
*OUT POST JCT 1 4.652 R
*OUT PRE JCT 2 4.044
*OUT PRE JCT 5 5.978
*OUT PRE JCT 10 7.603
*OUT PRE JCT 100 13.708
*OUT PRE JCT 1 3.121
*OUT R-40 JCT 2 5.500
*OUT R-40 JCT 5 7.693
*OUT R-40 JCT 10 9.486
*OUT R-40 JCT 100 16.019
*OUT R-40 JCT 1 4.419
SIN:
Bentley PondPack (10.00.027.00)
Max
Qpeak Qpeak Max WSEL Pond Storage
hrs cfs ft ac-ft
---------
12.2000 -------- -------- ------------
51.12
12.2000 87.62
12.2000 110.47
12.1500 156.98
12.0500 33.41
12.1500 67.85
12.1500 94.99
12.1500 115.96
12.1500 171.82
12.0000 49.63
12.1500 93.90
12.1500 122.14
12.1500 143.34
12.1500 196.13
12.0000 71.72
Bentley Systems, Inc.
5:00 PM 5/19/2011
Type.... Master Network Summary Page 1.02
Name.... Watershed
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage
Node
----- ID
--------
---- Type
---- Event
------ ac-ft
---------- Trun hrs
--------- cfs
-------- ft
-------- ac-ft
------------
POND 1 IN POND 2 1.669 12.1500 27.99
POND 1 IN POND 5 2.251 12.1500 34.74
POND 1 IN POND 10 2.720 12.1500 39.57
POND 1 IN POND 100 4.400 12.1500 51.40
POND 1 IN POND 1 1.377 12.0000 22.33
POND 1 OUT POND 2 1.659 12.3000 11.55 356.00 .775
POND 1 OUT POND 5 2.241 12.2500 22.36 356.36 .888
POND 1 OUT POND 10 2.710 12.3000 23.16 356.72 1.004
POND 1 OUT POND 100 4.389 12.3500 24.24 357.70 1.340
POND 1 OUT POND 1 1.369 12.2000 6.40 355.66 .673
POND 2 IN POND 2 1.995 12.1500 33.46
POND 2 IN POND 5 2.691 12.1500 41.53
POND 2 IN POND 10 3.252 12.1500 47.31
POND 2 IN POND 100 5.260 12.1500 61.44
POND 2 IN POND 1 1.647 12.0000 26.70
POND 2 OUT POND 2 1.976 R 12.3000 13.68 326.12 .922
POND 2 OUT POND 5 2.672 R 12.3000 24.39 326.61 1.099
POND 2 OUT POND 10 3.232 R 12.2500 35.35 326.81 1.178
POND 2 OUT POND 100 5.238 R 12.2000 53.92 327.12 1.295
POND 2 OUT POND 1 1.629 12.2000 7.91 325.77 .796
PRE - AREA' l AREA 2 1.005 12.1500 16.87
PRE - AREA 1 AREA 5 1.486 12.1500 23.62
PRE - AREA 1 AREA 10 1.890 12.1500 28.83
PRE - AREA 1 AREA 100 3.408 12.1500 42.72
PRE - AREA 1 AREA 1 .776 12.0000 12.34
PRE - AREA 2 AREA 2 1.202 12.1500 20.17
PRE - AREA 2 AREA 5 1.777 12.1500 28.23
PRE - AREA 2 AREA 10 2.260 12.1500 34.47
PRE - AREA 2 AREA 100 4.074 12.1500 51.07
PRE - AREA 2 AREA 1 .928 12.0000 14.75
SIN:
Bentley PondPack (10.00.027.00)
5:00 PM
Bentley Systems, Inc.
5/19/2011
Type.... Master Network Summary Page 1.03
Name.... Watershed
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Return HYG Vol
Node ID
-----------
--
---- Type
---- Event
------ ac-ft Trun
----------
R-40 AREA 1 AREA 2 1.367
R-40 AREA 1 AREA 5 1.913
R-40 AREA 1 AREA 10 2.359
R-40 AREA 1 AREA 100 3.983
R-40 AREA 1 AREA 1 1.099
R-40 AREA 2 AREA 2 1.635
R-40 AREA 2 AREA 5 2.287
R-40 AREA 2 AREA 10 2.820
R-40 AREA 2 AREA 100 4.761
R-40 AREA 2 AREA 1 1.313
TO BMP 1 AREA 2 1.669
TO BMP 1 AREA 5 2.251
TO BMP 1 AREA 10 2.720
TO BMP 1 AREA 100 4.400
TO BMP 1 AREA 1 1.377
TO BMP 2 AREA 2 1.995
TO BMP 2 AREA 5 2.691
TO BMP 2 AREA 10 3.252
TO BMP 2 AREA 100 5.260
TO BMP 2 AREA 1 1.647
UNTREATED AREA 2 2.105
UNTREATED AREA 5 3.036
UNTREATED AREA 10 3.809
UNTREATED AREA 100 6.672
UNTREATED AREA 1 1.654
UNTREATED - PRE AREA 2 1.836
UNTREATED - PRE AREA 5 2.715
UNTREATED - PRE AREA 10 3.453
UNTREATED - PRE AREA 100 6.225
UNTREATED - PRE AREA 1 1.418
Max
Qpeak Qpeak Max WSEL Pond Storage
hrs
--------- cfs ft ac-ft
-------- -------- ------------
12.1500 23.35
12.1500 30.37
12.1500 35.64
12.1500 48.77
12.0000 17.83
12.1500 27.91
12.1500 36.30
12.1500 42.60
12.1500 58.30
12.0000 21.32
12.1500 27.99
12.1500 34.74
12.1500 39.57
12.1500 51.40
12.0000 22.33
12.1500 33.46
12.1500 41.53
12.1500 47.31
12.1500 61.44
12.0000 26.70
12.1500 35.75
12.1500 48.40
12.1500 58.04
12.1500 82.97
12.0000 26.69
12.1500 30.81
12.1500 43.14
12.1500 52.66
12.1500 78.03
12.0000 22.54
SIN:
Bentley PondPack (10.00.027.00)
Bentley Systems, Inc.
5:00 PM 5/19/2011
Type.... Master Network Summary Page 1.04
Name.... Watershed
File.... K:\10110-00601100061-Preston - HL' Nor_th1H-H1Phase IV SWMP\PondPaklHighcroft IV- R
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=OuLfa.IL; 4•Node=Diversion;)
(True= HYG Truncation: Blank-gone; L-Left; R-- L; €,R-Left&RC)
Return
Node ID
---------------- Type Event
- ---- ------
UNTREATED R--40 AREA 2
UNTREATED R-40 AREA 5
UNTREATED R-40 AREA 10
UNTREATED R-40 AREA 100
UNTREATED R-40 AREA 1
FIYG Vol Qpeak Qpeak
ac-ft True hrs cfs
---------- --
2.498 ---------
12.1500 --------
42.54
3.494 12.1500 55.47
4.308 12.1500 65.09
1.275 12.1500 89.07
2.007 12.0006 32.57
Max
Max WSEL Pond Storage
ft ac-ft
-------- ------------
SIN: Bentley Systems, Inc.
Bentley PondPack [10.00.027.00] 5:00 PM 5/19/2011
Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 2.01
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
Title... Project Date: 12/5/2007
Project Engineer:
Project Title: Highcroft Wet Ponds
Project Comments:
DESIGN STORMS SUMMARY
Design Storm File,ID - RDU NOAA 14 Desi
Storm Tag Name = 2
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 2yr
2 yr
3.4400 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 5
Data Type, File, ID = Time-Depth Curve RDU NOAA 5yr
Storm Frequency = 5 yr
Total Rainfall Depth= 4.3000 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 10
Data Type, File, ID = Time-Depth Curve RDU NOAA 10yr
Storm Frequency = 10 yr
Total Rainfall Depth= 4.9800 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 100
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 100yr
100 yr
7.3700 in
1
23.9990 hrs
.0000 hrs Step= .0833 hrs End= 23.9990 hrs
Storm Tag Name = 1
Data Type, File, ID = Synthetic Storm TypeII 24hr
Storm Frequency = 1 yr
Total Hainf,all m?pth- 1,000n in
Duration Multiplier = 1
Resulting Duration 24.0000 hrs
ResulLiny SLarL Time= .0000 lirs Step= .1000 hrs End1 24.0000 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Design Storms Page 2.02
Name.... RDU NOAA 14 Desi Event: 2 yr
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
Storm... RDU NOAA 2yr Tag: 2
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 2
Data Type, File, ID = Time-Depth Curve RDU NOAA 2yr
Storm Frequency = 2 yr
Total Rainfall Depth= 3.4400 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 5
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 5yr
5 yr
4.3000 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 10
Data Type, File, ID = Time-Depth Curve RDU NOAA 10yr
Storm Frequency = 10 yr
Total Rainfall Depth= 4.9800 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 100
Data Type, File, ID = Time-Depth Curve RDU NOAA 100yr
Storm Frequency = 100 yr
Total Rainfall Depth= 7.3700 in
Duration Multiplier = 1
Resulting Duration = 23.9990 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9990 hrs
Storm Tag Name = 1
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Synthetic Storm TypeII 24hr
1 yr
3.0000 in
1
24.0000 hrs
.0000 hrs Step= .1000 hrs End= 24.0000 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Name.... PRE - AREA 1
Page 3.01
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
TIME OF CONCEN'1R A'."ICN CA€,C€ LATER
Segment #1: Tc: Kirpich (TN)
Hydraulic Length 2000.00 ft
Slope .030000 ft/ft
Multiplier 1.000 (Tc Adjustment)
Avg.Velocity 3.18 ft/sec
Segment #1 Time: .1746 hrs
------------------------------------------------------------------------
Total Tc: .1746 hrs
---------------
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... 'PC CaIcs
Name .... PRE - AREA 1
Page 3.02
F'il.e.... K:110110-00601100051-Preston - HV NorthlH-EilPhase fV SWMP1PondPaklHi9hcroft IV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
==== Rirpich (TAI) =_====---------------------- _____________
Tc = 0.00013 ' (Lf**0.77) . (Sf"-0.385) ' Mt
Where: Tc = Time of concentration, hrs
Lf = Flow length, ft
Sf = Slope, ft/ft
Mt = Tc Multiplier (Tc adjustment)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Name.... PRE - AREA 2
Page 3.03
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
Segment *I- Tc: Kirpich (TN)
Hydraulic Length 2000.00 ft
Slope .030000 ft/Et
multiplier 1.000 (Tc Adjustment)
Avg.Velocity 3.18 ft/sec
Segment #1 Time: .1746 hrs
------------------------------------------------------------------------
Total Tc: .1746 hrs
------------------------
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
`E'ype.... Tc. Calrs
Name.... PRE - AREA 2
Page 3.04
File.... K:\10110-00601100061-Preston - HV North\R-H\Phase IV SWMplPondPaklHighcroft IV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
= == Kirpich (TN)
To = 0.030013 * (Lf'+0.77) * (sf*•-6.385) * Mt
Where: Tc = Time of concentration., hrs
Lf = Flow length, ft
Sf = Slope, Et/ft
Mt = Tc Multiplier (Tc adjustment)
SIN: Bentley Systems, Inc.
Bentley Pond Pack (10.00.07.00) 5.00 PM 5/19/2011
Type.... T:- Calcs
Name.... R-40 AREA 1
Page 3.45
File.... K:\10110-0060\100061-Preston - HV North\H-M Phase IV SWMP1P0ndPak\Highcroft IV- R
TIME OF CONCENTRATION CALCULATOR
Segment #1: Tc: Kirpich (TN)
Hydraulic Length 2000.00 ft
Slope .030000 ft1>=t
Multiplier 1,000 (Tc Adjustment)
Avg.Velocity 3.18 ft/sec
Seament #1 Time: .1746 hrs
------------------------------------------------------------------------
- - - - - - - - - - - -
Total Tc: .1746 hrs
SIN: Bentley Systems, Inc.
Bentley Pond Pack (10.00.027.00) 5:40 Phi 5/19/2011
Type.... Te Calcs
Name.... R-40 P.R!A 1
Pave 3.06
File.... K-.\10\10-0060\100061.-Preston - HV North\H-H\Phase IV SNMP1PondPak\Highcroft IV- R
------------------------------------------------------------------------
Tc Equations use=d...
------------------------------------------------------------------------
==== Kirpich (TN) ______
Tc - 0.00013 ' (Lfo?0.77) } (Sf"-0.385) ? Mt
Where: Tc = 'rime of concentration, hrs
Lf = Flow length, ft
Sf. = Slope, ft/ft
Mt = Tc Multiplier (Tc adjustment)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.40.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Name.... R-47 AREA 7
Page 3.07
F'ile.... K.\10110-006011004361-Prestan - HV NorthlH-H1Phase IV SWMPIPondPak\Highcroft IV- R
TIME OE' CONCENTRATION CALCULATOR
Segment 41: Tc: Kirpich
Hydraulic Length 2000.00
Slope .030000
Multiplier 1.000
Avg.Velocity 3.18
-------------------------
(TN)
fr
ft/ft
(Tc Adjustment)
ft/sec
Segment #1 Time: .1746 hrs
----------------------------------------------
Total Tc: .1746 hrs
SIN: Bentley Systems, Inc.
Bentley Pap.d2ack (10.00.027.00? 5:R0 PM 5/19/2011
Type.... Tc Calcs
Name.... P-40 AREA 2
Page 3.08
File.... K:110\10--00501100061-Preston - HV NorthlH-H1Phase IV 51dMP\?ondPaklHighcroft IV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
__== Kirpich (TN) ====_______________________
'I'c = 0.00013 r (Lf*'0.77) * (Sf**-0.385) * Mt
Where: Tc = Time of concentration, hrs
Lf = Flow length, ft
SF = Slope, ft/ft
Mt = Tc Multiplier (Tc adjustmentf
SIN:
Bentley Pond Pack (10.00.027.00)
5:00 PH
Bentley Systems, Inc.
51181203.1
Type.... Tc Calcs
Name.... TO BMP 1
Page 3.09
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment 91: Tc: User Defined
Segment #1 Time: .0830 hrs
------------------------------------------------------------------------
------------------------
Total Tc: .0830 hrs
Caiculated Tc C Min.Tc:
Use Minimum Tc...
Use Tc = .0833 hrs
51N: Bentley Systems, Inc.
Bentley PcndPack 41r1. ]s7. ;??.001 5 ,0 PP; 5/19/2011
Type.... Tc Calcs
Name.... TO BMP 1
Page 3.10
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
User Defined =_____°__---------°----------------------------------
Tc = Value entered by user
Where: Tc = Time of concentration
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Name .... TO BM P 2
Page 3.11
File..., K:110110-00601100061-Preston - HV NorthlH-H\Phase IV SWMP1PondFaklHighcroft IV- R
SF OF CONCENTRATION CALCULATOR
Segment #1; Tc: User Defined
Segment #1 Time: .0830 hrs
------------------------------------------------------------------------
Total Tc; .0830 hrs
Calculated Tc e Min.Tc:
Use Minimum Tc...
Use Tc = 0833 hrs
---- - ---------
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Name.... TO BMP 2
Page 3.12
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
---= User Defined ==-------------------
Tc = Value entered by user
Where: Tc = Time of concentration
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Vame.... UNTREATED
Page 3.13
File.... K:110110-00601100061-Preston - HV NorthlH-HiPhase IV SWMPlPondPak\Highcroft IV- R
TIME ?F CONCENTRATION CALCULATOR
Segment #l: Tc: Kirpich (TN)
Hydraulic Length 2000.00 ft
Slope .030000 ft/ft
multiplier 1.000 (Tc Adjustment)
Avg.Velocity 3.1B ft/sec
Segment ill Time- .1746 hrs
------------------------------------------------------------------------
-------------------
Total Tc: .1746 hrs
SIN.- Bentley Systems, Inc.
Bentley PotjdPac.. { 10.00 .027. ()C! 5:00 ='M 5/19/2011
Type.... Tc Cales
Name.... UNTREATED
Page 3.14
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
Kirpich (TN) ----------------------- =========------ -------
T c = 0.00013 * (Lf**0.77) * (Sf**-0.385) * Mt
Where: Tc = Time of concentration, hrs
Lf = Flow length, ft
Sf = Slope, ft/ft
Mt = Tc Multiplier (Tc adjustment)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5119.12011
Type.... Tc Calcs
Name.... UNTREATED - PRE
Page 3.15
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
.........................................................................
Segment #1: Tc: Kirpich {TN}
Hydraulic Length 2000.00 ft
Slope .030000 ft/ft
Multiplier 1.000 (Tc Adjustment)
AVg.Velocity 3.18 ft/sec
Segment #1 Time: .1746 hrs
------------------------------------------------------------------------
------------ ------------
Total Tc: .1746 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
'1yF>Q.... Tc Calcs
Name.... UNTREATED - PRE
Page 3.16
C'ile.... K:R10110-00601100061-Preston - HV North\H-H\Phase 1V SWMP1PondPak\Highcroft TV- R
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
Kirpich (TN)
Tc = 0.00013 * (Lf*"0.77) * (Sf**-0.395) * Mt
Where: Tc = Time of concentration, hrs
Lf = Plow length, ft
Sf = Slope, ft/ft
Mt = Tc Multiplier (Tc adjustment)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Tc Calcs
Name.... .JN REATE© R-40
Page 3.17
File.... K:110110-00601.100061-Preston - HV North\H-H1Phase IV SWMPlPondPak\Highcroft IV- R
TIME OF CONCENTRAT10N CALCULATOR
-------------------------
Segment ill: Lc: Kirpich
Hydraulic Length 2000.00
Slope .030000
Multiplier 1.000
Avq.Velocity 3.18
-------------------------
----------------------------------------------
(TN)
£t
ft/ft
(Tc Adjustment)
ft/sec
Segment 91 Time: .1746 hrs
----------------------------------------------
Total Tc: .1746 hrs
-------------------------
SIN: Bentley Systems. Inc.
Bentley PondPack !10.00.027.001 5:00 PM 5/19/2011
Type.... 9'c Ca!cs
Name,.... UNTREATED R-40
Page 3.18
File.... :x:110010-0060110006:1-Preston - [IV NorthlH-MPhase IV S'.gMPlPondPaklHighcroft IV- R
------------------------------------------------------------------------
Tc Eesuations used...
--
Te = 0.00013 * (Lf4*0.77) * (Sf**-0.385) * Mt
Where: Tc = Time of concentration, hrs
Lf = Flow length, ft
St = Slope, ft/ft
Mt = Tc Multiplier (Tc adjustment)
SIN: Bentley Systems, Inc..
Bentley PoadPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Runoff CN-Area
Name.... PRE - AREA 1
Page 4.01
File.... R:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres oC oUC CN
-------------------------------- ---- --------- ----- ----- ------
Woods - good 77 8.700 77.00
COMPOSITE AREA & WEIGHTED CN ---> 8.700 77.00 (77)
...........................................................................
...........................................................................
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Ty,ae.... Runoff CSI-Area
Name.... PRE - AREA 2
Page 4.02
File.... K:\10110-0060!100051--Preston - HV NorthlH-HiPhase IV SWMP1PondPaklHighcroft IV- R
RUNOFF CURVE; NUMBER DATA
--------------------------------------------------------------------------
impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C %UC CN
-------------------------------- ---- --------- ----- ----- ------
Woods - good 77 10.400 77.00
COMPOSITE AREA & WEIGHTED CCN ---? 10.400 77.00 (77)
SIN: Bentley Systems. Inc.
Bentley Pond Pack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Runoff CN-Area
Flame.... R-40 AREA 1
Page 4.03
File.... K:110/10-00501100051-Preston - HV Mortn1H-H\Phase IV SWMP\PondPaklHighcroft IV- R.
RUNOFF CURVE NUMBER DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C %UC CN
-------------------------------- ---- --------- ----- ----- __----
Residential Districts - 1 acre 84 8.700 84.00
COMPOSITE AREA. S WTF]1G] ;:D C1,11 ---? 8.701) 84.00 (84)
SIN: Bentley Systems, Inc.
Bentley Pond Pack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Runoff CN-Area
hamQ.... R-40 AREA 2
Page 4.04
File.... K.\1011.0-006011.00061-Preston - HV North\H-H\Phase €V SWMPl2ondPak\HJghcroft IV- R
RUMOi= F CURVE NUMSFR DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Gescri.pLion CN acres %C %UC Ch
-------------------------------- ---- --------- ----- ----- ------
Residential Districts - 1 acre 84 10.400 84.00
COMPOSITE. AREA & WEIGHTED CN --? 10.400 84.00 (84)
SIN: Bentley Systems, Inc.
Bentley Pond Pack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Runoff CN-Area
Name.... TO BMP 1
Page 4.05
File.... K:\10\10-0060\100051-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres aC %UC CN
-------------------------------- ---- --------- ----- ----- ------
Impervious 98 4.410 98.00
Open space (Lawns,parks etc.) - Goo 80 4.290 80.00
COMPOSITE AREA & WEIGHTED CN ---> 8.700 89.12 (89)
...........................................................................
...........................................................................
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type .... ? if?of °: CSI-Area
Name .... ['0 2HP 2
Page 4.06
File.... K:110110-00601100061-Preston - HV NorthlH-H\Phase IV SWMP\PondPaklHighcroft IV- R
RUNOFF CURVE NUMBER DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C ;UC CN
-------------------------------- ---- --------- ----- ----- ------
Impervious 98 4.950 98.00
Open space (Lawns parks etc.) - Goo 80 5,950 80.00
COMPOSITE AREA Lii, iI ') 86.5'' f '9
SIN: Bentley Systems, Inc.
Bentley Pond Pack {10.00.027.00) 5:00 PM 5/19/2011
Type.... Runoff CN-Area
Name.... UNTREATED
Page 4.07
File.... K:110110-00601100061-Preston - HV North\H-H1Phase IV SWMP1PondPaklHighc:roft IV- R
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
impervious
Area Adjustment Adjusted.
Soil/Surface Description CN acres %C %UC CN
-------------------------------- ---- --------- ----- ----- ------
Woods - good 77 15.890 24.30 79.55
COMPOSITE AREA & WEIGHTED CN ---> 15.890 79.55 (80)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Runoff CN-Area
Name.... UNTREATED - PRE
Page 4.08
File.... K:110110-0060!100061.-Preston - HV North%H-fi\Phase IV SWMP\PondPak\Highcroft IV- R
RUNOFF CURVE NUMBER DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres 1C %LJC CN
-------------------------------- ---- --------- ----- ----- ------
Woods - good -77 15.890 77.00
C(-)MPCSI L AREA S VI:: T' :1'I E:D CH -- 13.09 77.CI;
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 FM 5/19/2011
Type.... Runoff CN-Area
Name.... UNTREATED R-40
Page 9.09
F'ile.... :x:110110-00501100051-2reston - HV NorthlH-H\Phase IV aWMP\PondPaklHighcroft IV- R
RUNOFF CURVE NUMBER DATA
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C %UC CN
-------------------------------- ---- --------- ----- ----- ------
Residential Districts - I acre 89 15.890 89.00
001,1 M i_E ..:Ei. n W IGHTED CN ---> 15.890 84.00 (84)
SIN: Bentley Systems, Inc.
Bentley PondPack (10,00.027.00) 5:00 PM 5/19/2011
Type.... Vol: Elev-Area
Name.... POND 1
Page 5.01
File.... K:110010-00601100061-Preston - HV NorthlH-H1Phase TV SWMP\PondPak\Highcroft IV- R
Elevation Pl.animeter Area Al+A2+sqr(A1*A2) Volume Volume Sum
(ft)
------------ (sq.in) (sq.ft)
-------
------------- (sq.ft)
----------------- (ac-ft)
--------- (ac-ft)
-------------
353.00 -
------ 8105 a .000 .000
354.00 °---- 10938 28459 .218 .218
355.00 ----- 12133 34591 .265 .482
356.00 ----- 13377 36250 .'-33 .775
357.00 ----- 14668 42053 .322 1.097
358.00 -°--- 15986 45967 .352 1.449
359.00 ----- 17220 49798 .381 1.830
360.00 ----- 18500 53569 .410 2.240
POND VOLUME EQUATIONS
* incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (113) * (EL2-EL1) * (Areal +- Area2 f sq.rt.(Areal1Area2))
where; ELI, EL2 = Lower and upper elevations of the increment
Areal,Area2 = Areas computed for ELI, EL2, respectively
Volume = Incremental volume between ELI and EL2
SIN. Bentley Systems, Inc.
Benti.ey PondPac€: (10.00.027.00) 5.00 PM 5119/2011
Type.... Vol: Elev-Area
Name.... POND 2
Page 5.02
File.... K:110110-00601100061-Preston - HV NorrhlH-H\Phase IV SWMP1PoadPaklHighcroft IV- R
Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum
(ft) (sq.in) (sq.ft) (sq.ft) (ac-ft) (ac-ft)
-----------
323.00 ----------------------
----- 9131 -----------------
0 ---------
.000 -------------
.000
324.00 ----- 12274 31992 .245 .245
325.00 ----- 13777 39055 .299 .544
326.00 ----- 15369 43697 .334 .878
327.00 17019 48561 .372 1.250
328.00 - --- 18725 5359E 1.660
329.00 ----- 20501 58619 .450 2.110
330.00 -- --- 22362 61427" .492 2.602
POND VOLUME EQUATIONS
* Incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (113) * (EL2--EL1) * (Areal + Areal + sq.rt.(Area1*Ar.ea2))
where: ELI, EL2 = Lower and upper elevations of the increment
Areal,Area2 = Areas computed for ELI, EL2, respectively
volume - Incremental volume betwcon ELI and EL2
SIN: Bentley Systems, Inc.
Bentley Pond Pack (10.00.027.00) 5:00 FM 5/19/2011
Pype.... Outlet Input Data
Name.... Outlet 1
Page 6.01
File.... K:110110-006[71100061-Presr_on - HV North\H-klPhase TV SWMP1PonCiPaF:lllighcroft IV- R
REQUESTED POND WS ELEVATrONS:
Min. Elev.= 353.00 ft
Increment = .10 ft
Max. Elev.= 360.00 ft
1F*+***ir*#**'k++*W*A,****'J, 0,**k? **'******AY.
OUTLET CONNECTIVITY
---? Forward Flow Only (llpStream to DnStream)
[--- Reverse Flow Only (DnStream to Upstream)
[---? Forward and Reverse Both Allowed
Structure
----------------- No.
---- Outfall
------- E1, ft
--------- E2, ft
--____n__
weir-Rectangular WO ---? CO 355.000 360.000
Inlet Box RO ---? co 356.000 360.000
Orifice-Circular 00 ---? CO 353.000 360.000
Culvert-Circular CO ---> TW 350.000 360.000
TW SETUP, DS Channel
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 501912011
Type.... Outlet Input Data
flame.... Outlet 1
Page '0.02
File.... K:110110-00601100061-Preston - HV NorthlH-H\Phase IV SWMP\PondPaklHighcrcft IV- R
OUTLET STRUCTURE INPUT DATA
Structure ID
Structure Type
--------------
# of openings
Crest Elev.
Weir Length
Weir Coeff.
WO
Weir-Rectangular
----------------
1
355.00 ft
9.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure 1D = RO
Structure Type =
-
-
-
- Inlet Sox
--
-
--
----
--
-------
--
# of Openings - ----
-----
---
i
Invert Elev. - 356.00 ft
orifice Area = 25.0000 sq.ft
orifice Coeff. _ .600
Weir Length = 16.00 ft
Weir Coeff. = 3.000
K, Reverse = 1.000
Mannings n - .0000
Kev,Charged Riser = .000
Weir Submergence = No
Structure 10 = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 353.00 ft
Diameter = .1670 ft
Orifice Coeff. _ .600
Slid: Bentley systems, Inc.
Bentley Pond Pack [10.00.027.00] 5:00 PM 5/19/2011
Type.... Outlet Input Data
Name.... Outlet 1
Page 6.03
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
------------------ = Culvert-Circular
------------------
No. Barrels = 1
Barrel Diameter = 1.5000 ft
Upstream Invert = 350.00 ft
Dnstream Invert = 345.00 ft
Horiz. Length = 128.00 ft
Barrel Length = 128.10 ft
Barrel Slope = .03906 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .018213
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0018
Inlet Control M = 2.0000
Inlet Control c = .02920
Inlet Control Y = .7400
T1 ratio (HW/D) = 1.043
T2 ratio (HW/D) = 1.188
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below Tl elev.
Use submerged inlet control Form 1 equ. above T2 elev.
In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at T1 & T2...
At Tl Elev = 351.56 ft ---> Flow = 7.58 cfs
At T2 Elev = 351.78 ft ---> Flow = 8.66 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maximum Iterations= 40
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Composite Rating Curve
Name.... Outlet 1
Page 6.04
File.... K:\10\10-0060\100061-2reston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ----- --- Converge ---------- --- ------------
Elev. Q TW Elev Error
ft cfs ft +/-ft Contributi ng Structures
--------
353.00 -------
.00 -----
Free --- -----
Outfall -----------
(no Q: WO ---
,RO ------------
,OO,CO)
353.10 .01 Free Outfall OO,CO (no Q: WO,RO)
353.20 .04 Free Outfall OO,CO (no Q: WO,RO)
353.30 .05 Free Outfall OO,CO (no Q: WO,RO)
353.40 .06 Free Outfall OO,CO (no Q: WO,RO)
353.50 .07 Free Outfall OO,CO (no Q: WO,RO)
353.60 .08 Free Outfall OO,CO (no Q: WO,RO)
353.70 .08 Free Outfall OO,CO (no Q: WO,RO)
353.80 .09 Free Outfall OO,CO (no Q: WO,RO)
353.90 .09 Free Outfall OO,CO (no Q: WO,RO)
354.00 .10 Free Outfall OO,CO (no Q: WO,RO)
354.10 .11 Free Outfall OO,CO (no Q: WO,RO)
354.20 .11 Free Outfall OO,CO (no Q: WO,RO)
354.30 .12 Free Outfall OO,CO (no Q: WO,RO)
354.40 .12 Free Outfall OO,CO (no Q: WO,RO)
354.50 .13 Free Outfall OO,CO (no Q: WO,RO)
354.60 .13 Free Outfall OO,CO (no Q: WO,RO)
354.70 .13 Free Outfall OO,CO (no Q: WO,RO)
354.80 .14 Free Outfall OO,CO (no Q: WO,RO)
354.90 .14 Free Outfall OO,CO (no Q: WO,RO)
355.00 .15 Free Outfall OO,CO (no Q: WO,RO)
355.10 .53 Free Outfall WO,00,CO (no Q: RO)
355.20 1.22 Free Outfall WO,00,CO (no Q: RO)
355.30 2.10 Free Outfall WO,OO,CO (no Q: RO)
355.40 3.14 Free Outfall WO,OO,CO (no Q: RO)
355.50 4.30 Free Outfall WO,OO,CO (no Q: RO)
355.60 5.57 Free Outfall WO,OO,CO (no Q: RO)
355.70 6.95 Free Outfall WO,00,CO (no Q: RO)
355.80 8.42 Free Outfall WO,OO,CO (no Q: RO)
355.90 9.96 Free Outfall WO,00,CO (no Q: RO)
356.00 11.59 Free Outfall WO,00,CO (no Q: RO)
356.10 14.77 Free Outfall WO,RO,OO,C O
356.20 19.25 Free Outfall WO,RO,OO,C O
356.30 22.08 Free Outfall WO,RO,OO,C O
356.40 22.54 Free Outfall WO,RO,OO,C O
356.50 22.88 Free Outfall WO,RO,OO,C O
356.60 23.04 Free Outfall WO,RO,OO,C O
356.70 23.13 Free Outfall RO,CO (no Q: WO,00)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Composite Rating Curve
Name.... Outlet 1
Page 6.05
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -- ----- --- Converge ------ ---- --- ------------
Elev. Q TW Elev Error
ft cfs ft +/-ft Contributi ng Structures
--------
356.80 -------
23.25 -----
Free --- -
Outfall ------
RO,CO ----
(no ---
Q: ------------
WO,00)
356.90 23.36 Free Outfall RO,CO (no Q: WO,00)
357.00 23.47 Free Outfall RO,CO (no Q: WO,00)
357.10 23.58 Free Outfall RO,CO (no Q: WO,00)
357.20 23.69 Free Outfall RO,CO (no Q: WO,00)
357.30 23.80 Free Outfall RO,CO (no Q: WO,00)
357.40 23.91 Free Outfall RO,CO (no Q: WO,00)
357.50 24.02 Free Outfall RO,CO (no Q: WO,00)
357.60 24.13 Free Outfall RO,CO (no Q: WO,00)
357.70 24.24 Free Outfall RO,CO (no Q: WO,00)
357.80 24.35 Free Outfall RO,CO (no Q: WO,00)
357.90 24.46 Free Outfall RO,CO (no Q: WO,00)
358.00 24.56 Free Outfall RO,CO (no Q: WO,00)
358.10 24.67 Free Outfall RO,CO (no Q: WO,00)
358.20 24.77 Free Outfall RO,CO (no Q: WO,00)
358.30 24.88 Free Outfall RO,CO (no Q: WO,00)
358.40 24.98 Free Outfall RO,CO (no Q: WO,00)
358.50 25.09 Free Outfall RO,CO (no Q: WO,00)
358.60 25.19 Free Outfall RO,CO (no Q: WO,00)
358.70 25.30 Free Outfall RO,CO (no Q: WO,00)
358.80 25.40 Free Outfall RO,CO (no Q: WO,00)
358.90 25.51 Free Outfall RO,CO (no Q: WO,00)
359.00 25.61 Free Outfall RO,CO (no Q: WO,00)
359.10 25.71 Free Outfall RO,CO (no Q: WO,00)
359.20 25.81 Free Outfall RO,CO (no Q: WO,00)
359.30 25.91 Free Outfall RO,CO (no Q: WO,00)
359.40 26.01 Free Outfall RO,CO (no Q: WO,00)
359.50 26.11 Free Outfall RO,CO (no Q: WO,00)
359.60 26.21 Free Outfall RO,CO (no Q: WO,00)
359.70 26.31 Free Outfall RO,CO (no Q: WO,00)
359.80 26.41 Free Outfall RO,CO (no Q: WO,00)
359.90 26.51 Free Outfall RO,CO (no Q: WO,00)
360.00 26.61 Free Outfall RO,CO (no Q: WO,00)
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Outlet Input Data
Name.... Outlet 2
Page 6.06
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 323.00 ft
Increment = .10 ft
Max. Elev.= 330.00 ft
**********************************************
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to UpStream)
<---> Forward and Reverse Both Allowed
Structure
----------------- No.
---- Outfall
------- El, ft
--------- E2, ft
---------
Weir-Rectangular WO ---> CO 325.000 330.000
Inlet Box RO ---> CO 326.500 330.000
Orifice-Circular 00 ---> CO 323.000 330.000
Culvert-Circular CO ---> TW 320.000 330.000
TW SETUP, DS Channel
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/1912011
Type.... Outlet Input Data
Name.... Outlet 2
Page 6.07
File.... K:110110-006{)1100451-Preston - HV NorthlH-H\Phase IV SWMPIPondPak\Highcroft IV- R
OUTLET STRUCTURE: INPUT DATA
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Caeff.
W0
Weir-Rectangular
----------------
1
325.00 ft
4.00 ft
3.000000
Weir TW effects (Use adjustment equati.orO
Structure ID = RD
Structure Type
------------------- = Inlet Sox
-----------------
a of Openings - I
Invert Elev. = 326.50 ft
Orifice Area = 25.0000 sq.ft
Orifice Coeff. _ .600
Weir Length = 16.00 ft
Weir Coeff. = 3.000
K, Reverse - 1.000
Mannings n = .0000
Kev,Charged Riser = .000
Weir Submergence = No
Structure ID = OO
Structure Type = Orifice-Circular
------------------------------------
k of Openings = 1
Invert Elev. = 323.00 €t
Diameter - .1570 ft
Orifice coeff. -• .600
SIN: Bentley Systems, Inc.
Bentley Pond Pack (10.00.027.00) 5:00 PM 51191207.1
Type.... Outlet Input Data
Name.... Outlet 2
Page 6.08
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
----------------- = Culvert-Circular
-------------------
No. Barrels = 1
Barrel Diameter = 2.5000 ft
Upstream Invert = 320.00 ft
Dnstream Invert = 319.00 ft
Horiz. Length = 82.00 ft
Barrel Length = 82.01 ft
Barrel Slope = .01220 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .009217
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0018
Inlet Control M = 2.0000
Inlet Control c = .02920
Inlet Control Y = .7400
T1 ratio (HW/D) = 1.056
T2 ratio (HW/D) = 1.201
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below T1 elev.
Use submerged inlet control Form 1 equ. above T2 elev.
In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at T1 & T2...
At T1 Elev = 322.64 ft ---> Flow = 27.16 cfs
At T2 Elev = 323.00 ft ---> Flow = 31.05 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 40
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance .00 cfs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Composite Rating Curve
Name.... Outlet 2
Page 6.09
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ----- --- Converge ---------- --- ------------
Elev. Q TW Elev Error
ft cfs ft +/-ft Contributing Structures
--------
--------
323.00 -------
.00 -----
Free ---
Outfall -----------
(no Q: WO ---
,RO ----
,OO,CO)
323.10 .01 Free Outfall OO,CO (no Q: WO,RO)
323.20 .04 Free Outfall OO,CO (no Q: WO,RO)
323.30 .05 Free Outfall OO,CO (no Q: WO,RO)
323.40 .06 Free Outfall OO,CO (no Q: WO,RO)
323.50 .07 Free Outfall OO,CO (no Q: WO,RO)
323.60 .07 Free Outfall OO,CO (no Q: WO,RO)
323.70 .08 Free Outfall OO,CO (no Q: WO,RO)
323.80 .09 Free Outfall OO,CO (no Q: WO,RO)
323.90 .09 Free Outfall OO,CO (no Q: WO,RO)
324.00 .10 Free Outfall OO,CO (no Q: WO,RO)
324.10 .11 Free Outfall OO,CO (no Q: WO,RO)
324.20 .11 Free Outfall OO,CO (no Q: WO,RO)
324.30 .12 Free Outfall OO,CO (no Q: WO,RO)
324.40 .12 Free Outfall OO,CO (no Q: WO,RO)
324.50 .12 Free Outfall OO,CO (no Q: WO,RO)
324.60 .13 Free Outfall OO,CO (no Q: WO,RO)
324.70 .13 Free Outfall OO,CO (no Q: WO,RO)
324.80 .14 Free Outfall OO,CO (no Q: WO,RO)
324.90 .14 Free Outfall OO,CO (no Q: WO,RO)
325.00 .15 Free Outfall OO,CO (no Q: WO,RO)
325.10 .53 Free outfall WO,OO,CO (no Q: RO)
325.20 1.22 Free Outfall WO,00,CO (no Q: RO)
325.30 2.10 Free Outfall WO,OO,CO (no Q: RO)
325.40 3.14 Free Outfall WO,OO,CO (no Q: RO)
325.50 4.30 Free Outfall WO,OO,CO (no Q: RO)
325.60 5.58 Free Outfall WO,OO,CO (no Q: RO)
325.70 6.95 Free outfall WO,OO,CO (no Q: RO)
325.80 8.42 Free Outfall WO,OO,CO (no Q: RO)
325.90 9.96 Free Outfall WO,00,CO (no Q: RO)
326.00 11.57 Free Outfall WO,OO,CO (no Q: RO)
326.10 13.26 Free outfall WO,OO,CO (no Q: RO)
326.20 15.01 Free Outfall WO,OO,CO (no Q: RO)
326.30 16.81 Free Outfall WO,OO,CO (no Q: RO)
326.40 18.68 Free Outfall WO,OO,CO (no Q: RO)
326.50 20.57 Free Outfall WO,OO,CO (no Q: RO)
326.60 24.05 Free Outfall WO,RO,OO,CO
326.70 28.82 Free Outfall WO,RO,OO,CO
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Type.... Composite Rating Curve
Name.... Outlet 2
Page 6.10
File.... K:\10\10-0060\100061-Preston - HV North\H-H\Phase IV SWMP\PondPak\Highcroft IV- R
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
----- --- Converge ------------- ------------
Elev. Q TW Elev Error
ft cfs f t +/-ft Contributing Structures
--------
326.80 -------
34.42 -----
Free ---
Outfall --------------
WO,RO,OO,CO ------------
326.90 40.74 Free Outfall WO,RO,OO,CO
327.00 47.64 Free Outfall WO,RO,OO,CO
327.10 53.34 Free Outfall WO,RO,OO,CO
327.20 57.02 Free Outfall WO,RO,OO,CO
327.30 59.91 Free Outfall WO,RO,OO,CO
327.40 62.08 Free Outfall WO,RO,OO,CO
327.50 63.66 Free Outfall W0,R0,O0,C0
327.60 64.75 Free Outfall WO,RO,OO,CO
327.70 65.43 Free Outfall WO,RO,OO,CO
327.80 65.95 Free Outfall RO,CO (no Q; WO,00)
327.90 66.47 Free Outfall WO,RO,OO,CO
328.00 66.93 Free Outfall RO,CO (no Q: WO,00)
328.10 67.45 Free Outfall RO,CO (no Q: WO,00)
328.20 67.96 Free Outfall RO,CO (no Q: WO,00)
328.30 68.46 Free Outfall RO,CO (no Q: WO,00)
328.40 68.96 Free Outfall RO,CO (no Q: WO,00)
328.50 69.45 Free Outfall RO,CO (no Q: WO,00)
328.60 69.95 Free outfall RO,CO (no Q. WO,00)
328.70 70.45 Free Outfall RO,CO (no Q: WO,00)
328.80 70.93 Free Outfall RO,CO (no Q: WO,00)
328.90 71.41 Free Outfall RO,CO (no Q: WO,00)
329.00 71.89 Free Outfall RO,CO (no Q: WO,00)
329.10 72.37 Free Outfall RO,CO (no Q: WO,00)
329.20 72.87 Free Outfall RO,CO (no Q: WO,00)
329.30 73.30 Free Outfall RO,CO (no Q: WO,00)
329.40 73.77 Free Outfall RO,CO (no Q: WO,00)
329.50 74.24 Free Outfall RO,CO (no Q: W0,O0)
329.60 74.69 Free Outfall RO,CO (no Q. W0,O0)
329.70 75.15 Free Outfall RO,CO (no Q: WO,00)
329.80 75.60 Free Outfall RO,CO (no Q: WO,00)
329.90 76.05 Free Outfall RO,CO (no Q: WO,00)
330.00 76.51 Free Outfall RO,CO (no Q: WO,00)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
Appendix A
Index of Starting Page Numbers for ID Names
Outlet 1.., 6. 01, 5.04
Outlet 6.06, 6.09
POND 1... 5.01
POND 2... 5.02
PRE - AREA 1... 3.01, 4.01
PRE - AREA 2... 3.03, 4.02
----- R -----
R-40 AREA 1... 3.05, 4.03
R-40 ARVA 2.... 3.07, 4.04
ROU NOAA 14 Desi... 2.01, 2.02
T
TO BML? 1... 3.09, 4.05
TO BMP 2... 3.11, 4.05
-°--- U -----
UNTREATED... 3.13, 4.07
UNTREATED - !ARE... 3.15, 4.013
UNTREATED R-40... 3.17, 4.09
Watershed... 1.01
A-1
S/N; Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 5:00 PM 5/19/2011
BMP SIZING
CALCULATIONS
Highcrott Village Phase IV W&R Praje[t 2otooo6l
5tormwater Management Report July 2011
Project Name: Highcroft Phase IV
City/State: Cary, NC
Project #: 2040191
Date: 7-j u I-11
Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant
RPmnval Fffiripnrv in the PiPdmnnt
% Impervious
Cover Permanent Pool Dept
3.0 4.0 5.0 6.0 h (feet)
7.0 8.0 9.0
10 0.59 0.49 0.43 0.35 0.31 0.29 0.26
20 0.97 0.79 0.70 0.59 0.51 0.46 0.44
r
30 1.34 1.08 0.97 0.83 0.70 0.64 0.62
40 1.73 1.43 1.25 1.05 0.90 0.82 0.77
50 2.06 1.73 1.50 1.30 1.09 1.00 0.92
60 2.40 2.03 1.71 1.51 1.29 1.18 1.10
70 2.88 2.40 2.07 1.79 1.54 1.35 1.26
80 3.36 2.78 2.38 2.10 1.86 1.60
1.42
90 3.74 3.10 2.66 2.34 2.11 1.83 1.67
Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 5, April 1999
STORMWATER BMP 1 - WET POND (25% TN REMOVAL)

Land Use Area
(ac) % IA Imp. Area
(ac)
Impervious 4.41 98 4.3
Open Space 4.29 0 0.0

Totals 8.7 4.3
Total % Impervious Surface Area = 49.7 %
Surface Area of Permanent Pool:
Assumed depth = 3 feet
SA/DA ratio = 2.05 % From Table 1.1
Minimum pond surface area (SA) = (DA * SA/DA ratio)/100
SA = 0.178 acres
7766 sq. ft.
Normal pool elevation = 353.0 feet
Surface area provided = 0.186 acres
8105 sq. ft.
1-Inch Runoff Volume Calculation
Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987)
Rv = 0.05 + 0.009(1) where, Rv = Runoff coefficient, in./in.
I = Percent impervious
Rv = 0.50 in./in.
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 0.360 acre-ft
15698 cu. ft.
Water quality pool elevation= 355.00 feet
Storage volume provided = 0.482 acre-ft
20996 cu. ft.
Project Name: Highcroft Phase IV
City/State: Cary, NC
STORMWATER BMP - WET POND (25% TN Removal)
Orifice Calculator
Q =Cd*A*(2gh)"(1/2)
Variables
WQ Volume:
Head:
Draw down time:
0.482 Acre-ft
2.00 ft
50 hrs
20995.92 cf
0.666667 ft
180000 s
Orifice Area =
0.02967 sq. ft
Orifice Diameter = 2.332348 in
USE 2.3 INCH DIAMETER ORIFICE
4.272444 sq. in
Project #: 2040191
Date: 7-j u l-11
Constants
g = 32.2 ft/sz
Cd = 0.6
0.116644
Project Name: Highcroft Phase IV
City/State: Cary, NC
Project #: 2040191
Date: 7-J u I-1 1
Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant
Removal Efficiencv in the Piedmont
% Impervious
Cover Permanent Pool Dept
3.0 4.0 5.0 6.0 h (feet)
7.0 8.0 9.0
10 0.59 0.49 0.43 0.35 0.31 0.29 0.26
20 0.97 0.79 0.70 0.59 0.51 0.46 0.44
30 1.34 1.08 0.97 0.83 0.70 0.64 0.62
40 1.73 1.43 1.25 1.05 0.90 0.82 0.77
50 2.06 1.73 1.50 1.30 1.09 1.00 0.92
60 2.40 2.03 1.71 1.51 1.29 1.18 1.10
70 2.88 2.40 2.07 1.79 1.54 1.35 1.26
E 80 3.36 2.78 2.38 2.10 1.86 1.60 1.42
90 3.74 3.10 2.66 2.34 2.11 1.83 1.67
Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 5, April 1999
STORMWATER BMP 2 - WET POND (25% TN REMOVAL)

Land Use Area
(ac) % IA Imp. Area
(ac)
.Impervious 4.95 98 4.9
Open Space 5.45 0 0.0

Totals 10.4 4.9
Total % Impervious Surface Area = 46.6 %
Surface Area of Permanent Pool:
Assumed depth = 3 feet
SA/DA ratio = 1.95 % From Table 1.1
Minimum pond surface area (SA) = (DA * SA/DA ratio)/100
SA = 0.203 acres
8831 sq. ft.
Normal pool elevation = 323.0 feet
Surface area provided = 0.210 acres
9131 sq. ft.
1-Inch Runoff Volume Calculation
Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987)
Rv = 0.05 + 0.009(1) where, Rv = Runoff coefficient, in./in.
I = Percent impervious
Rv = 0.47 in./in.
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 0.407 acre-ft
17736 cu. ft.
Water quality pool elevation= 325.00 feet
Storage volume provided = 0.544 acre-ft
23697 cu. ft.
Project Name: Highcroft Phase IV
Ci State: Cary, NC
STORMWATER 6MP - WET POND (25% TN Removal)
Orifice Calculator
Q =Cd*A*(2gh)"(112)
Variables
WQ Volume:
Head:
Draw down time:
0.544 Acre-ft
2.00 ft
77 hrs
23696.64 Cf
0.666667 ft
277204 s
Orifice Area =
0.021744 sq. ft
Orifice Diameter= 1.996682 in
USE 2 INCH DIAMETER ORIFICE
3.131176 5q. in
Project #: 2040191
Date: 7-j u I-11
Constants
g = 32.2 fd52
Cd = +0.6
0.085486
NITROGEN LOADING
CALCULATIONS
Highcroft Village Phase IV W&R Project 20100061
Stormwater Management Report July 2011
Nitrogen Control Plan
Commercial / Industrial / Residential Sites with Known Impervious Area
Project Title: Highcroft Village - Phase IV
Part I. Riparian Buffers
Area includes riparian buffers? [ ] No [ X ] Yes [ ] Exempt
If yes, [ X ] 50 foot [ ] 100 foot
River Basin? [ ] Neuse [ X ] Cape Fear
Basis for Exemption
Show buffers on site plan.
Part II. Nitrogen Calculations (Method 2, Appendix C):
a. Site Information
Total Area of Property incl. R/W
Denuded Area
Impervious Area incl. RAN
Managed open space
Protected open space
b. Pre-development loading:
Type of Land Cover
Permanently protected undisturbed open
space (forest, unmown meadow)
Permanently protected managed open space
(grass, landscaping, etc.)
Impervious Area
TOTAL
Nitrogen Loading Rate (Ibs/ac/yr) _
c. Post-development loading:
TN Export
Area TN export coeff from use
facrPSl fibs/ac/vrl Ilbslvrl
31.84 0.6 19.10
0 1.2 0
0 21.2 0
31.84 19.10
0.60
Type of Land Cover
Permanently protected undisturbed open
space (forest, unmown meadow)
Permanently protected managed open space
(grass, landscaping, etc.)
Impervious Area
TOTAL
TN Export
Area TN export coeff from use
1arrecl (ibstaclvr) Ilbslvr)
4.91 0.6 2.95
14.36 1.2 17.23
12.57 21.2 266.48
31.84 286.66
Nitrogen Loading Rate (Ibs/ac/yr) = 9.00
Proposed BMP(s) 2 Wet Detention Ponds
Nitrogen Load after BMPs = 5.26 Ibs/ac/yr
Net change in on-site N Load = 5.40 Ibs/ac/yr
Part III. Control of Peak Stormwater Flow (for 1 year, design storm)
Calculated Pre-development Peak Flow
Calculated Post-development Peak Flow
Proposed BMP(s)
Post BMP Peak Flow
31.84 acres
+/-28 acres
12.57 acres
14.36 acres
4.91 acres
49.86cfs
82.03 cfs
2 Wet Detention Ponds
33.29 cfs
I, the undersigned, certify to the best of my knowledge that the above information is correct (affix seal).
Supply notes & details showing control of Nitrogen and peak stormwater runoff.
.101Ir le io r, f1?s.
Nitrogen Control Plan
Commercial / Industrial / Residential Sites with Known Impervious Area
Project Name: Highcroft Village - Phase IV
Project #: 20100061
Estimated Post-Development TN Loading
Date: 4/14/2011
Computed by: AVS
Drainage Area I: Wet Pond I
Type of Land Cover Acres IN Export Coe .
(Ibs/ac/yr) TN EXPORT (Ibs/yr)
Permanently Protected Undisturbed Area 0.51 0.6 0.31
Permanently Protected Managed Area 3.64 1.2 4.37
Impervious Area 3.30 21.2 69.96
ota 5 7.45 74.63
rre rsnnr uradnage Area Loaning Kare: 1V.ue wuvdiryl
BMP Reduction: 25 %
Buffer Reduction 30 %
Drainage Area I Nitrogen Loading Reduction: 35.45 Ibs/yr
Post BMP Drainage Area Loading Rate: 5.26 Ibs/ac/yr
Drainage Area II: Wet Pond II
Type of Land Cover Acres TN Export Coet . TN EXPORT (Ibs/yr)
(Ibs/ac/yr)
Permanently Protected Undisturbed Area 0.00 0.6 0.00
Permanently Protected Managed Area 5.37 1.2 6.44
Impervious Area 5.08 21.2 107.70
Totals 10.45 114.14
rre tsmr 1lralnage Area coaaing Kare: iu.uc iu?.auyr
BMP Reduction: 25 %
Buffer Reduction 30 %
Drainage Area II Nitrogen Loading Reduction: 54.22 Ibs/yr
Post BMP Drainage Area Loading Rate: 5.73 Ibs/ac/yr
Untreated
Type of Land Cover Acres FN Export Coett. TN EXPORT (Ibs/yr)
(Ibs/ac/yr)
Permanently Protected Undisturbed Area 4.40 0.6 2.64
Permanently Protected Managed Area 5.35 1.2 6.42
Impervious Area 4.19 21.2 88.83
.1 97.89
Pre BMP Drainage Area Loading Rate: 1.Uz 10s/ac/yr
BMP Reduction: 0 °%
Buffer Reduction 30 °%
Nitrogen Loading Reduction: 29.37 Ibs/yr
Post BMP Drainage Area Loading Rate: 4.92 Ibs/ac/yr
Total Area: 31.84 Acres
Estimated Project Pre-BMP TN Export: 286.66 Ibs/yr
Estimated Project BMP TN Removal: 119.03 Ibs/yr
Estimated Project TN Load Rate After BMPs: 5.26 Ibs/ac/yr
Estimated Project Composite Nitrogen Loading Rate Reduction: 41.52 °%
Remaining Pounds to Offset = 53.00 Ibs/yr