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Home My WebLink About20050732 Ver 07_Stormwater Info_20071029 (3)~~os-fl~3aU7 Tf~ JOHN R McADAMS COMPANY, INC. LETTER OF TRANSMITTAL To: Ms. Lia Myott Date: October 25, 2007 NC Division of Water Quality 2321 Crabtree Blvd, Suite 250 Raleigh, North Carolina 27604 ** HAND DELIVER ** (919) 733-9502 Re: Briar Chapel -Phase 4 Job No.: NEW-05042 I am canriinn vni i tha fnllnwinn itam(cl• COPIES DATE NO. DESCRIPTION 1 A lication Fee -Check #71923 for $1,000 3 Letter Re: Stormwater M mt Plan Modification Re uest 3 Ex ress Review Stormwater Mana ement Plan A 3 BMP Supplement Forms and O&M Agreements 3 PH 4 Water Qualit Pond Construction Dw s 3 PH 4 Water Qualit Pond Final Desi n Calculations Booklets 3 Briar Cha el - PH 2 Construction Dw s Low-Densit 3 Briar Chapel -Great Ridge Parkway Roadway and Waterline Extension Low-Densit These are transmitted as checked below: ^ As requested ^ For your use ® For approval ^ For your signature ^ For review and comment ^ Remarks: Copy to: M. Sanchez Signed: K. Yates remy Finch, PE roject Manager FOR INTERNAL USE ONLY Q L~~~l~" \:! L~ ^ Copy Letter of Transmittal O_ my to File O C~. 2 t~ 207 ® Copy Entire Document to File pENFi - W,~,T~Ft C~i1ALtTY WE7LA-dD3 ANO STORMIk'~!AT~R BRAPICt~ CIVIL ENGINEERING LAND PLANNING • SURVEYING PO Box 14005 • Research Triangle Park, NC 27709 • (919) 361-5000 • fax (919) 361-2269 www.johnrmcadams.com Since 1979 THE JOHN R. McADAMS COMPANY, INC. BRIAR CHAPEL CHATHAM COUNTY, NORTH CAROLINA FINAL DESIGN CALCULATIONS WATER QUALITYPOND #4 • NEW-05043 ~;~y_ , ~..., .eft ~~tr`~ ~l'~~`t. e ~n~~°~'~°~~ ,~,Q~~~"~ib~~~~~~ ~~ a ~ ~~a_ August 2006 Revised: October 2007 Research Triangle Park, NC Post Office Box 14005 Research Triangle Park, North Carolina 27709 2905 Meridian Parkway Durham, North Carolina 27713 800-733-5646 919-361-5000 919-361-2269 Fax Charlotte, NC 5311 Seventy-Seven Center Drive, Suite Ct orth Carolina 28217 80~ 46 704-527-0800 704-527-2003 Fax (?(~ ~~~ D 1~ `°' oc~ ~ ~ ~zao~ Beth Ihnatolya, EI p ~~i ~~ ~~"~ ~p a~ Associate Project Engine Jeremy V. Finch, PE Stormwater Project Manager Comprehensive Land Development Design Services www.johnrmcadams.com We help our clients succeed. ~x.p ®5 - 0~3 a y7 i• BRIAR CHAPEL -PHASE IV Final Design -Water Quality Pond #4 General Description Located off from US Highway 15-501, north of Andrews Store Road and south of Mann's Chapel Road in Chatham County, NC is the proposed development known as Briar Chapel. Phase IV of the proposed development is approximately 140-acres and will consist of mostly single-family lots, along with the associated utility, parking, and roadway infrastructure. This report contains the final design calculations for water quality pond #4,. which is located within Phase IV of Briar Chapel. The proposed development is located within the Cape Fear River Basin, and drains to streams (Pokeberry Creek & Wilkinson Creek) classified as Water Supply IV (WS-IV), and Nutrient Sensitive Waters (NSW). As a result of the proposed development exceeding the maximum allowable limit for stream impacts, an individual permit issued by The United States Army Corps of Engineers (USAGE) is required (Clean Water Act Section 404 permit). Also, a Clean Water Act Section 401 Water Quality Certification from NCDWQ will be attached to the individual permit. Under the 401 Water Quality Certification from NCDWQ, the proposed site will be required to comply with the stormwater management requirements set forth in the Water Quality Certification #3402 (WQC #3402). WQC #3402 has the following water quality requirements: 1. Site specific stormwater management shall be designed to remove 85% total suspended solids (TSS) according to the latest version of DWQ s stormwater Best Management Practices Manual at a minium. 2. In watersheds within one mile and draining to 303(d) listed waters, as well as ~ watersheds that are classified as nutrient sensitive waters (NSYI~, water supply waters (WS), trout waters (Tr), high quality waters (HWQ~, and outstanding resource waters (ORW), the Division shall require that extended detention wetlands, bioretention areas, and ponds followed by forested filter strips (designed according to the latest version of the NCDENR stormwater Management Practices Manual) be constructed as part of the stormwater management plan when asite-specific stormwater management plan is required. In addition to the above stormwater quality requirements, the following stormwater quality and quantity items are required per Section 8.3 ("stormwater Controls") of the Chatham County Compact Communities Ordinance: 1. Control and treat the first inch of runoff from the project site and from any offsite drainage routed to an on-site control structure. Ensure that the draw down time for this treatment volume is a minimum of forty eight (48) hours and a maximum of one hundred and twenty (120) hours. 2. Maintain the discharge rate for the treatment volume at or below the pre- development discharge rate for the 1 year, 24-hour storm. • To address these stormwater requirements, a water quality pond with a preformed scour • hole/level spreader outlet that will provide sheet flow of the 1" runoff volume into -the stream buffer is proposed for construction as part of the development of phase IV of Briar Chapel. This report contains the design calculations for water quality pond #4 only. This water quality pond will be designed so that both the water quality and water quantity requirements described above are satisfactorily met. Calculation Methodology - Rainfall data for the Chatham County, NC region is derived from USWB Technical Paper No. 40 and NOAH Hydro-35. This data was used to generate adepth-duration-frequency (DDF) table describing rainfall depth versus time for varying return periods. These rainfall depths were then input into the meteorological model within HEC-HMS and PondPack for peak flow rate calculations. Please reference the rainfall data section within this report for additional information. - Using maps contained within the Chatham County Soil Survey, the on-site soils were determined to be predominantly from hydrologic soil group (HSG) `B' and HSG `C' soils. Since the method chosen to compute the post-development peak flow rates and runoff volumes is dependent upon the soil type, all hydrologic calculations are based upon the assumption of HSG `B' and HSG `C' soils. - A composite SCS Curve Number was calculated for the post-development condition using SCS curve numbers and land cover conditions. Land cover conditions for the post- development condition were taken from the proposed development plan. - The post-development time of concentration to the water quality pond was assumed to be ~ • 5 minutes in the post-development condition. - All on-site topo was taken from a topographic survey performed by The John R. McAdams Company, Inc. The drainage map for the post-development condition has been included in this report. - HEC-HMS Version 2.2.2, by the U.S. Army Corps of Engineers, was used to generate post-development peak flow rates for water quality pond #4. Routing calculations for the pond were also performed within HEC-HMS. - Pondpack Version 8.0, by Haestad Methods, was used to generate the stage-discharge rating curves for the proposed water quality pond. These rating curves were input into HEC-HMS for routing calculations. - The stage-storage rating curve and stage-storage function for the proposed water quality pond were both generated externally in a spreadsheet and then input into HEC-HMS. - A velocity dissipater is provided at the end of the principal spillway outlet for the water quality pond to prevent erosion and scour in the downstream areas. The dissipater is constructed using riprap, underlain with a woven geotextile filter fabric. The filter fabric is used to minimize the loss of soil particles beneath the riprap apron. The dissipater is sized for the 10-year storm event using the NYDOT method. It is a permanent feature of the outlet. • - Water quality sizing calculations were performed in accordance with the N.C. Stormwater • Best Management Practices manual (NCDENR April 1999). The normal pool surface area for the water quality pond was sized by calculating the average depth and then selecting the appropriate SA/DA ratio from the water quality pond section of the NCDENR manual. A temporary storage pool for the 1" runoff volume is provided in the pond, to be drawn down in 2 to 5 days using an inverted siphon. - For 100-year storm routing calculations, a "worst case condition" was modeled in order to insure the proposed pond would safely pass the 100-year storm event. The assumptions used in this scenario are as follows: 1. The starting water surface elevation in the pond, just prior to the 100-year storm event, is at the top of the principal spillway structure. This scenario could occur as a result of a clogged siphon or a rainfall event that lingers for several days. This could also occur as a result of several rainfall events in a series, before the inverted siphon has an opportunity to draw down the storage pool between NWSE and the riser crest elevation. 2. An attempt was made to achieve a minimum of approximately 0.5-ft of freeboard between the peak elevation during the "worst case" scenario and the top of the dam for the pond. - The downstream tailwater elevation for the pond was assumed to be a free outfall condition during the 1-year storm event (a conservative assumption). - The 100-year tailwater elevation for the pond was assumed to be free outfall because the • 100-year floodplain elevation downstream of the pond is below the invert out elevation. i Discussion of Results As previously stated, this report contains the final design calulations for the proposed water quality pond #4 located within phase IV of the Briar Chapel development. Ultimately, there will be a total of six (6) water quality ponds for phase IV of Briar Chapel. The final design for the remaining water quality ponds is under separate cover. These ponds will function as "dual- purposed facilities" by providing both water quality and water quantity (for the 1-year storm only). Please refer to the Summary of Results tables for additional information. C.'nnclu.cinn If the development on this tract is built as proposed within this report, then the requirements set forth in the Water Quality Certification #3402 (WQC #3402) and Section 8.3 ("Stormwater Controls") of the Chatham County Compact Communities Ordinance will be met with the proposed water quality pond. However, modifications to the proposed development may require that this analysis be revised. Some modifications that would require this analysis to be revised include: 1. The proposed site impervious surface exceeds the amount accounted for in this report. 2. The post-development watershed breaks change significantly from those used to prepare this report. The above modifications may result in the assumptions within this report becoming invalid. The computations within this report will need to be revisited if any of the above conditions become apparent as development of the proposed site moves forward. BRIAR CHAPEL SUMMARY OF RESULTS B. IHNATOLYA, EI NEW-05043 Water Quality Pond #4 10/17/2007 • I~• Return Period Inflow [cfs] Outflow [cfs] Maa. WSE [ft] 1-Year 64.0 1.3 421.60 10-Year 142.7 67.0 422.50 25-Year 172.8 111.6 422.90 100-Year (Siphon Clogged) 219.3 157.7 423.45 Design Draina e Area = 27.98 acres Desi Irn ervious Area = 14.52 acres To of Dam = 424.00 ft Re uired Surface Area /Draina e Area Ratio = 1.73 Surface Area at NWSE = 36163 sf Re uired Surface Area at NWSE = 21052 sf Si hon Diameter = 3 inches Total Number of Si hons = 1 Riser Len h = 6 ft Riser Width = 6 ft Riser Crest = 421.55 ft Barrel Diameter = 42 inches # of Barrels = 1 Invert In = 414.30 feet Invert Out = 414.00 feet Len = 54 feet Slo e = 0.0056 ft/ft Emer enc S illwa Crest = 422.95 ft Emergency Spillway Length = 30 ft • ,.~ • RAINFALL DATA 2 SOILS DATA 3 US GEOLOGICAL SURVEY MAP 4 FEMA FLOODPLAIN MAP POST-DEVELOPMENT HYDROLOGIC 5 CALCULATIONS WATER QUALITY POND #4 FINAL 6 DESIGN CALCULATIONS • ~y,~ 05 -132 V~} ~~ RAINFALL DATA • BRIAR CHAPEL NEW-05043 B PEL B. IH LYA, EI NFL • /19/2006 I. INPUT DATA Location; Durham, North Carolina 2-Year : 100-Year Source 5 minute E v 0.48 . : 0:81 NOAA Hydro-35 .................. .... 15 minute ........... ............ - 1.Oi 1.81 NOAA H dro-35 60 minute 's 1.70 3.~0 NOAA H dro-35 24 hour 3.60 8.00 USWB TP-40 II. DEPTH-DURATION-FREQUENCY TABLE Return Period Duration 2-Year 5-Year 10-Year ~ 25-Year 50-Year 100-Year [inches] [inches] [inches] [inches] [inches] [inches] 5 minutes 0.48 0.55 0.60 0.68 0.75 0.81 10 minutes 0.79 0.92 1.02 1.17 1.28 1.40 15 minutes 1.01 1.18 1.31 1.51 1.66 1.81 30 minutes 1.35 1.64 1.85 2.16 2.40 2.64 60 minutes 1.70 2.12 2.41 2.84 3.17 3.50 2 hours 1.91 2.40 2.74 3.23 3.61 4.00 3 hours 2.12 2.68 3.07 3.62 4.06 4.49 6 hours 2.65 3.38 3.90 4.62 5.19 5.75 12 hours 3.13 4.02 4.64 5.52 6.20 6.88 24 hours 3.60 4.65 5.38 6.41 7.21 8.00 III. INTENSITY-DURATION FREQUENCY DATA Return Period T Duration 2-Year E 5-Year 10-Year 25-Year 50-Year 100-Year [in/hr] [in/hr] [in/hr] [in/hr] [in/hr] (in/hr] 5 minutes 5.76 6.58 7.22 8.19 8.96 9.72 10 minutes 4.76 5.54 6.13 7.01 7.71 8.40 15 minutes 4.04 4.74 5.25 6.03 6.64 7.24 30 minutes 2.70 3.28 3.71 4.32 4.80 5.28 60 minutes 1:70 2.12 2.41 S ..__.2:84...._. ..__._3.:17 ....... ......3:50....._.. .. ._. 2 hours .._....... 0.95 1.20 1.37 1.62 1.81 2.00 3 hours 0.71 0.89 1.02 1.21 1.35 1.50 6 hours 0.44 0.56 0.65 0.77 0.86 0.96 12 hours 0.26 0.33 0.39 .0:46 0.52 0.57 24 hours 0.15 0.19 0.22 0.27 0.30 0.33 N. RESULTS 2 132 18 ............................... 5 ..................... lii9 ...................... 21. ............................... 10 ..................... 1!Iti ..... . ...................... 22 ................. .... ............................... 25 ........... ... ''32 . 23 50 2 F,1 24 BRIE PEL B. IH LYA, EI • ~/ 19/2006 NEW CALCULATIONS: 1/I Duration 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 5 0.17 0.15 0.14 0.12 0.11 0.10 10 0.21 0.18 0.16 0.14 0.13 0.12 15 0.25 s 0.21 0.19 0.17 0.15 0.14 30 ~:37 ~ x:30 0.27 : 0.23 .... . . 0.21 ..................... 0.19 ...................... ............ ........._. 60 ........ .......... .. 0.59 ._.. ... 0.47 .-• .............. . . -----......... 0.41 ........... .. . 0.35 0.32 0.29 120 1.05 0.83 0.73 0.62 0.55 0.50 180 1.42 1.12 0.98 0:83•._...• ,•.••, 0:74.••••. .,.._..0 :67....... 360 ?:26 1:x? 1:54............ Y . ....1:30....... ......1:16....... .......104....... .......... 720 ......... ...........;.. 3.84 ... .... 2.99 .... .............. 2.59 2.18 1.94 1.75 1440 6.67 5.16 4.46 3.75 3.33 3.00 2-Year 5-Year 10-Year i 25-Year - esr - ear S1o e: 0.00760 ? 0.00592 0.00513 0.00430 0.00383 0.00344 Y-Intercept: 0:13587 0.12225 0.11255 0.10001 0.09181 0.08486 ...~ : ...........132........._.;.......169....... ..... ..........195............... :.......232.._.... .......261....... ......290........ ........ ........... h: 18 21 22 23 24 25 • • • 0 1 :--- _ -___.____ 19 -~ :' _ r -- '~ ,_.~ - - - --_. _: ~. ,- ter., --~. _.~ -~-~~~ ~~.. ' -- - - -- ,_ , ~K ~y - , f ~ I - _... -'-t-.-_ _ it t.'-__ _y • t~ /-~ _ _ - - _ -- ~-- r -- ..-~---. ~ Xb Rf.(;ipry .7EXT1"- _ - - .- _' ~ ~~ ~ .. / • .~. ' ~s ~S ~' I _ _- J _ _ - ~ ~ _ --_ _ _ 1~ - - _ - _~- ~- ~- ._ _' -y -_ Lepend.. -%~ 1- ! 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J~"?"•'i'~.. -. _ mfr • -', . ~ ~ `. •• .. ~•' YEAR 15•MINUTE PRECIPITATION L~--~ ~ +-'~" - •`~' -} '' --' *. j ~.1 y - ._~ , 1. ,~ t ~ ~•r_ _ ~ ' ~.v ~'..~~ .-~ Y ~~"~ -,"1-~~'" *KEt MfEST•ADRIDA VALUE f '1 - ~'•~? =-- 1'--" ~ RE-AE SE HTATIVE FOII f1O1110A XkYS. ~~~1' _~~~ X125 J~'u,,,~~~ i ~c i r ` v~r i = t _ _ c ~ c to ~~ ' '~ ~~ ~ . 4 ~, ~ r • ~/ ~.r...• ~ w •.r n 1 ~~ ~ r (inches)--~,1Uated to partial-durat~n aeries. ~5_~n precip~•atatativr, . '•, _.._. ~. ~s•••~ - - .~. -. ~.~ :G"uw~%...rr _sir. iii.-:n..,.~-,~:...,.:; •: a..-«~. :..~ -- a r _ • ~S ~~- -- _ r . •Y i r i ~ ~ ~.•~ ~S --~ ~---- -'~- ~; ' ~ 1~ / ~ _.. ~.y ... ~ 0 b '•r. ~ 1 •~..~ `r. ~ t0 r~.A ~th~~ S :~ . 1. .~ ;~ ro ^___ ~ hf~__ .~i :4 /.. ill. •~ J 1' ~ 2•YEAR 80-MINUTE PRECIPITATION 1 __ ~ f . , .?i. ~••• IINCNESI 1. Tt.,' ~ t ~ ,- ~ ,• 4 ~ '~i ~ ~1 •' ~° r~ t *KEY WEST, /LOR10A VALUE t -~~ _ •elr .. -- , ~• ~• 1 . _ 11 11EPRtbENTATIVE /011 /IOAIDA I(E'13. •ry. 2 ~ •e ~ ~ f ' ..ri ,,~1,. i.i ~.,~ . . '' -'l5 ~k- •~ 1 j s._.. ~ .~ ~ ....~_.. r ~ lt~* . ~~ ~ __ __ ; ___ _-_.- r ye;~_,n-{;,1 precipitation (finches)--adjusted to parttiaZ dumttion series. page blank • • • '.;:Yrfn:R'i'A?n7a d~~...~ ~._ - `~cli':4(:V~- "3~..'~~ •+l!.ar..+~=5+"'•".l_ ~,.e.r.'~:^1~rJ:.-+rt;'~'""'"°t' • 21 w - .. » .- • ~~, _~ _ w ~ _ '~ _ . ,~ ~~': ~.. '_ .may. ~?~\~"~-l `l- ,. y`• ~~^ x ',_ _ ~ .en -- -~., ~' i~--~l i -~ .: ~. r ~Y Yom.- ..c._ ~ _ - _ _ -1~ _- ^. ~ - _ < ~ .~,." ~ r ..-.,-. - - i .jam ~.~ ' =~ ~--,r.~ ~ _ --~ Y- ~_~ --' _ ~~ -`;'l - _ ~i ec ~. 100-YEAR S~MINUTE PRECIPfTATION L-rte _~--~ _-_~-~___ _`:.,r _i-' -~ ~I (INCHESI / .,/~~~ . ? t _ ~! _--~ -- - ~ ~ ~ j ~` KEY WEST. F101110A VALUE ~~ _ '"~ _ ~ ~_ ~ _- ~ ~ "~ T'; - ~~ -~ REVflESEHTATIVf FOR FLORIDA KE75. ~ f~,y ~. ~ '~ ~... ,y.' of _~ T" i ._ T O G !! 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FLORIDA VAWE ~s A.. .t ~ 1, /~ ~^~. y •~ ~ t ~ ~•~ 4.;~.tt REFAESENTATIVE FdN Fl ORK7A KEYS. j f ~~,~ ~ T Y Q I ~ •. ~ 2.1 ., ' O ~ , __ 2.0 ~ G U L I .: - ~ 2. `~ 2'~ 11~ ` } ~ ~ .. ,,/ L.;~~..~~ "/ - I.eI* L Y X M r ~~ 1 '~r r ,~- „~• IS-mimcte precipitation (inches)--adjusted to partial-dtcratt,on aeries. ~• 25 rpl[/li4~lf1~'rv,k'~wa~n:r~'~.w '. Er~...~ r.-.'~~5=°''~rv~!!~'^s"1v ~e~r1~•.~. t 7 __ -- ' i • - 70 ~ ' r. J • G r / 2 0 r( r / r ~ r 1 an ~• .. _. to 25 2:5 '1 -nr 2 `~.: j~.5 ~, •~ - 'r - \_ 1~.. _ •~ 125 _~ vl i _tr •. •% 1 1 ~ - _ __ .{~ - -~ \a, ,1• :. ~• ',i~ ~~ ^1. .1125 • ~ ,~ • _. _. ... .V ]o t~ ~ J . .~:... . `. _f.. _ -1. - •~~•. ~.7 ~• : ~ is P ~_. - _ i .... '~ ,i~ . Upend: ~~- •• -~-~.' .`~ •, ~ ,~~•. ~ 100-YEAF 50 MINUTE PRECIPITA710N • r ~ ~ • ~ ~ '~~ *KEY WE31. ilOK10A vAIU[ ~j i _` I ~• .. . ~. - •. ,~y~` ~K[-1(SENTATIV[ fOR flORIOA KlYL. ' _ ,fir, •~.~_ 1.17 ~5 ~' .i~ I __ ~ r.-.-'f~u~.l r c / _ ~ . '~. ~ /' . I •~ . r ~~ ~ ~ t F ,. ~ ~~ t5 % ~ ~ R 1t I C O I I ~ , IS L I O I l5 1~ 101 '. ~_ C U ` v I fry _ _._. __. _ _....___.-_._--~- ' _.._.._ _... __.. .._ . ~ --~- ••^••• •••.~• arttial duration aeries. ar 60-minute precipitation (inches)--a~jtieted to p . •,, i i • • • ,m ~~ ~s -0'13 U7 ~~ SOILS' DATA • BRIAR CHAPEL NEW-05043 } i r , _. ,~ '~ ~ r -. ~r M A ~ 6 .a 1 iw i 1 l+ u ( ,. S ~. to J ~'4 6 r J y 1 / L,1 4 j~ ~,. ~~ t ~ .. '~ } ~. }E ',. ~ + h, y l¢1 6 n i~. ', ~ ' ~ ~ .... y ',°Yl 1 J r t" ~ d I ~ ~ydy ti?y a - t ~ l , M. J t r,v~ t!' PI , '~^'~ ~., F 1 7 ,.A ( 4 y ~.~~, J t. ~ IA 'Y ~ 5'~l ' 1Y l ~'~r ... S P Ir e .. „. ~ yg YY~~ + r r ~` t V ,.~" , r ~. a j r A 4 tx + >1 f „~ t ~ ~ ~, . ~?~ ,f oy.it Ya ti. 1 '` ,1 } .r.~C„ S r.' 7. tit t , r~ a~ ~ 7 ~ VV } ~ ~r . y 5`~4 -~ f ~ ~~; C l }• j 1,w,C ~C ~' •~l~S'' ,r,Gd! 4 A~ <,~ ,j ~ ~ m~ C '~ ~ i t :~, S 4 r} ,^ 1 t i !•r ~~ . ~ `" <~" u, . ,5~~~ { _ m.,r ) r ~ ~ F + 4~9 ys tl U .~. . °~ , ~ ~ 1 f . 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IHNATOLYA, EI NEW-05043 INFORMATION 10/16/2007 WQ POND #4 . => Watershed soils - To WQ Pond #4 Symbol Name Soil Classification 37C Wedowee Sandy Loam B 37D Wedowee Sandy Loam B 39C Wedowee Sandy Loam B 57B Vance Sandy Loam C References: 1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL CONSERVATION SERVICE. 1986. %HSGB= 92% HSG C = 8% => Conclusion Watershed soils are from 'HSG B' and 'HSG C'soils. The relative percentage of each HSG was calculated. These percentages were then used in the computation of the composite curve numbers. Cover Condition • Impervious Open SCS CN -HSGB 98 61 SCS CN -HSG C 98 74 Wooded 55 70 Cover Condition Composite SCS CN Impervious 98 Open 62 Wooded 56 • • ~.xp os - x'13 a ~7 US' GEOLOGICAL SURVEYMAP ,,~ • BRIAR CHAPEL NEW-05043 Copyright (C) 1998, Maptech, Inc FEMA FL OODPLAIN MAP • BRIAR CIIAPEL NEW-05043 • POST DEVELOPMENT HYDROLOGIC CALCULATIONS :~ BRIAR CHAPEL NEW-05043 I; :I ~C~ GRAPHIC SCALE 200 0 100 200 400 1 inch = 200 ft. _T O (0 C L a rn ai 0 N_ O O N M N O --~ ' ~ ® Pxo]ECT No. NEW-05043 PILENAME: B CHAPEL -PHASE IV THE JOHN R. McADAMS INC. COMPANY NEW05044X.DWG , ENGINEERS/PLANNERS/SURVEYORS ~ C SCALE: ,"=200' NORTH CAROLINA CHATHAM COUNTY NC RESEARCH TRIANGLE PARK y , , BOX 14005 ZIP 27709-4005 P O ' ~ HATE; WQ POND #4 DRAINAGE AREA EXHIBIT . . 5000 9 361 i 10-~~-2007 (91 ) - i BRIAR CHAPEL HYDROLOGIC CALCULATIONS B. IHNATOLYA, EI NEW-05043 Post-Development-To WQ Pond #4 10/16/2007 • • Cover Condition SCS CN Comments Im ervious 98 - 0 en 62 Assume ood Wooded 56 Assume ood Water 100 [Iti 1'OS'I`D~'ELOPlIENT-%. _> To WQ Pond #4 A. Watershed Breakdown Total Number of 50' Residential Lots = 52.5 lots Assumed Impervious Area Per 50' Residential Lot = 3200 squaze feet Total Impervious Area from 50' Residential Lots = 3.86 acres Total Number of 60' Residential Lots = 28.5 lots Assumed Impervious Area Per 60' Residential Lot = 3600 square feet Total Impervious Area from 60' Residential Lots = 2.36 acres Total Number of 70' Residential Lots = 16 lots Assumed Impervious Area Per 70' Residential Lot = 4200 squaze feet Total Impervious Area from 70' Residential Lots = 1.54 acres Total Roadway/Alleyway Impervious Area = 5.51 acres Total Sidewalk Impervious Area = 1.26 acres Contributing Area SCS CN Area [acres] Comments On-site o en 62 12.63 Assume ood condition On-site im ervious 98 14.52 - On-site wooded 56 0.00 Assume ood condition On-site water 100 0.83 - Off-site o en 62 0.00 Assume ood condition Off-site im ervious 98 0.00 - Off-site wooded 56 0.00 Assume ood condition Off-site water 100 0.00 Total area = 27.98 acres 0.0437 sq.mi. Composite SCS CN = 82 I SC5 C~I~R~'I~~L1111I3FRS?,~_ B. Time of Concentration Information Time of concentration was assumed to be a conservative S minutes Time of Concentration = 5.00 minutes SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc) = 0.0500 hours Time Increment = 0.87 minutes (= 0.29*SCS Lag) • HEC-HMS Project: NEW-05043 Basin Model: To WQ Pond #4 ,r.~ WQ''Pond #4 • HMS * Summary of Results Project NEW-05043 Run Name 1-Yr Post Rev !• Start of Run 07Ju102 0000 Basin Model Post-Development-Rev End of Run 07Ju103 0000 Met. Model 1-Year Storm Execution Time 170ct07 0849 Control Specs 1 Min dT Hydrologic Discharge Time of Volume Drainage Element Peak Peak (ac Area (efs) ft) (sq mi) To WQ Pond #4 WQ Pond #4 • 64.049 07 Jul 02 1157 3.2140 0.044 1.2596 07 Jul 02 1720 3.2140 0.044 • ~.~cp ~ 5- o ~ 3 a V~ WATER Q UALITY POND #4 FINAL DESIGN CALCULATIONS • BRIAR CHAPEL NEW-05043 i ~ 1 ~- WA1ER 9UAid1Y POND #4 CON5IRUCIION SPECIFICA170NS \'~, / ~ ~ -" - -"- I \' ----- 111 ^ II I \\ ----- I III ` I GENERAL N01ES BERM SOII. AND COMPAC110N SPECIFICATIONS , / ~ ~ 1 _ __ ,, _-- II II 'I 43s - _ I. PRIDA i0 CONSTRUCTON, ME CN-SITE GEOTEQINICAL ENGNEEp SHNL MEAIFY ME t. Nt FILL MATERULS 10 BE USED Fqi ME DAM EMUNNMENIS SH.NI BE \ I / I I ~ _ _ SUIUBIUIY W 1XE PRCP05ED BORROW WU /FILL FOR USE w ME GM TAKEN FROM BORROW WFAS APPROVED BX ME ON-SnE CEOTECHNICIL I ~. I I EMBWKMENTS / NEY rNENLN. ENGINEER. ME FILL NATERNL SHNL BE FREE FROM ROOTS, $NMPS, WOOD, ~.\ 1 ~ /I 4191 T STONES CRGTER DUN 6'. ANO FROZEN OA OTHER D6JECDONABLF ~ / I I _--'- 7. THE ON-SIZE CEORdINILN ENGINEER SHALL INSPECT ME NEY TRENCH EPGYAMIN IIgiERWL. ME FOLIONING SOIL 1YPE5 WE SURABLE FOR USE W FILL `50' CWNtt SMFTAJ ~ I /I j / I PRIOR i0 PUCEMENi OF 0.NY BICNFlLL WTNIN ME KEY 1RENCH. IF ME CDNTRACroR WITHIN THE DAM EMBANNMFM WD KEY TRENCH: NL AND CL WYFE EPNEMERN 9~ `_ I -__ WNSTRUCI5 WD COVERS UP ME KEY TRENCH PPoOA i0 INSPECDON, MEN ME NR Q ~ ) -~/ 11 I I I I 1A£NCN SHALL BE UNCOVERED WO TESTED AT ME CONiR4CTOR'S E%PENSE. 1. FlLL RACEMENi SH4L NOT EXCEED A NPXIMUM 6' UR. UCH UFT ' I I I ~ ~ ~/ I SHALL BE CONTINUOUS FOA ME ENTIRE IENLTH a EMflANNMENTS BEFORE I I II i , }. ME LWTFACiOA SHALL REFER ro ME UNDSCWE PIAN FOR ME PERWNENi PVCEMENi OF FILL FOA ME BERM SECTION, ALL UNSWTWIE MATEPVL ' _ j I / I j~~ PUNDYW; PLW/SCHEWLE. ME PERMWENi KGETAnON i0R ME PROPOSED SHALL BE RENWED Wp THE SURFACE PROPERLY PREPARED FOA FlLL ~ , I I I - ,~'I I EMBWNMENT $WLL BE TALL FESCUE. PLEASE NOTE iFUi NO iPEES/SNPoIBS Di ANY PUCEMENr. I '-~ . I I ,- PPE NAY BE PIANTED ON THE P0.0POSE0 DA4 EMWlNMENT (FlLL WF/S). ' I I I .--- I I /'.____` }. ILL FILL SOILS USED IN ME EMBNINMENR / kEY TRENCH I I I 4. IF ME WRIER ODNItt POND S i0 BE USED AS A SEDIMENT BASIx WRING WNSTRUCDDN SHALL BE LOMPACTEp TO Al IFJST 951 Oi THE STAHpARO / I I I 432 I I CONSTRUCTION, ME LONIR4CTOA SHALL NOT CONSTRUCT ME INiERX1A EWMEN RERN PROCTOR MW IMUM DRY pENSItt (ASTM-fi9Bj. ME FlLL SOILS SwLL BE i~,LTOR pGLL UNE iXE EMERGERq I 1 SHOWN W MIS RIN UNDL APPROVAL i0 REWVE ME $EOIMEM BASIN NA$ BEEN COMPACTED Ai A NgSMRE CON1ENi W1MIN -1 Lo t} PERCENT OF ITS Y AN IT CHANNEL WITH iRM 450.`, I ~ GAWTED BY ME EAOSON CONTROL wSPECTOR. OPTIMUM MdSTURE CONTENT. COMPACTON TESTS 9UNL ~ PERFCRMED BY HORI~PAFTEI>H FOR INSTALUDON ~ I I / I I THE ON-SITE CEOiECHNICAl ENGINEER pUPoNC CON57RUCDON i0 VERIFY SHAIE TH CNOR PATTERN SHOWN ON I I I I j I , 5. IF ME WATER OLNlltt POND IS i0 BE USED AS A SEd4ENi BASIN WRING THAT ME PROPER COMPKnON IFVEL HW BEEN RUCHED. ME RL \ a I I PD-tE. THE LINER.SHALL f# I , I I I / I CONSTRUCDON, ME WG SHALL BE CIFANED dD (I.E SEDMENT, 7M5µ ETC) WD SHOULD & COMPACTED USING A SHEEPSFODi ttPE COMPACTOR. IN ORDER I «EO PER MWUFAZNRERS \`I I I I i i0 PREVENT DAMAGE i0 ME PIPE, NO COMPICDON EgNMENT $W1L - SPC ~KJ 545. PLEASE NOR iWY ME 1 I I REVEGRARO (IF NELESSAFt) PRIOR i0 USE A$ A $1OHIIWATER LLVUCELTENi iACIUtt. ~ $tWEAG J6 R. SENtS W ADP0.0%I ro I I IIiOP OF pA4 iNE DUSx WO SEDIMENL SNOUID BE 06POSW Q< PROPERLY LE. - VNDFlLL. CFOSS AN! PIPE UNDL MINIMUM CO+FR R ESTPHLISHEO IlONG THE PVE „~ ~ I a I 430 ( ) N CC"THE T~ 450 U ER. I I b I 430 1 I IMWWTENNICC / !. A KEY TRENCH SHLI BE PRpADED AENGM ALL FILL WEAS OF ME 1 I I I I MCES$ / B. Nl REINFORCED CONCRETE FlAAED ENO SECnpN INLER INTO ME POND SHILL R l' a I UNDERINN WCH A ]000 F51 CONCRETE PAD. SEE pETA0.5 SHEET PD-4D, BERM. iNE TRENCH SHALL IXTENO A MINIMUM OF 5 R BELOW EXISnNC " ' -, II I CAADE AND SIULL HOVE A MINIMUM BOROM WIOM OF 5 FEET, THE NE1' ~yyy~; I'i y / I a I I MENCN SIOESLOPES SHLLL BE A MNINUM CF 1:1 (H:Y). ME KEi TRENCH .AFB \ i PEZO1 ~ ~ I I CONSTRUCT70N PREPARATION SHALL BE COMPACTED ro THE SANE SPECMGDON UETED IN rtEM 3 ABOVE HOROM WATER =•VO (MI J I I LR, . ELEV = ~ 95 I I ~I 9 I. PROR TO PUCEMEM OF ME NFW Fltl. ME WFA$ ON WHOH FlLL I$ 10 BE 5. UPoN AEOUEST, THE CONTRACTOR SHALL PROVTOE ME ENGNEER WIM ;Try?: gU+t "- 1.95 R. (M N.) I I 9 Ati8 ftEPORR i0 VERIFY INAT ME DIN EM&NXMENi MEETS ME SPECIFIED 1 I ~ ~ 1 \ I / PIACED SHALL BE CLFMED WD $iwPPFD Di iOPpIL TREES, R0015, VECRATIOrK, COMPACDDN REOUIREMENiS. COMPACDON REPORTS Wlll BE HEEDED OURNG I ]'I ( I I PNO OMER OBJECTgNWIE WTEAVL THE WG$ ON WHICH FlLL 6 i0 BE %ACEO iNE AS-WILT CERTIFIGTION PROCESS Fqt THIS STORMWATEA FACIUtt. PE ID a / \ 1 SHNL BE SGRIFlED. APP 0 / Ar`'p THEREFORE, IF 5 ME CONDUCTOR'S RESPONSIBILOY i0 ENSURE . ALgNT ~ nLLFO R I a lI/ I \ \ /7 _~" COMPACDON iFS15 ARE PROPERLY PERFORMED WRING CONSMUCiKIN. // \ \ g 2. 0.Nf AE40VE0 70PSdL SMALL BE ROLI(wLEU FOR USE w RANTING (SEEDING) ON m ` aANdFA"`uRER'$ S t4 U~!0 ME DAAI EMBWNMENiS ONCE FlNAL GRAlIES (W SHOWN DX ME GRld11NG PUN) H1YE E DE"k. Sn'WF >- ,ry I aEE1R EsrABUSHFD WM COMPADTEO FlLL SPIILWAY PEE SUBGRADE SUPPORTAND ~I /1 ~ ~ I. II ro-~ ' 'Wx _ --` ] THE CONTAACroA sxuE FluwlsN INSTIll, OPERATE, Nlo uNxGUn Nn PUMPwL BEDDING SPECIFICATIONS EiFE ewer 0..Wbz? ,~. ~Y ~ `~ n ~\ ` ~ -~ - - L EOUIPMENi, ETC. NEEDED FOR REMPlAI OF WARA FROM VWIOUS PARR OF ME ~3 1 ft N ``1 1 \ 0 F 1) ~ STORNWATER POND SRE li S ANTiCIPAIED THAT PUMPING WILL BE NECESSARY IN TNF L~"c' Lit ~'~ f ~C-.~ r~ I ~ h I \ \O !(, ~i ~ ' ~ ~~ I. FlLL IN THE ARU OF ME SPILLWAY PIPE AND ADV.CENT WEW SIMIUID sAN +Y H p :m F'.: i (-' I / IXGVADON INAS (LE. -KEY TRENCH. WRING PIACEMEM OF FlLL WDHIN THE NE'f .D" ~i F ~ A I IJ a THENLH (dt OTHER WFA$ AS NECESSWr) ME CONTRACTOR SHALL KEEP THE WAFER eE BROUGHT W TO A POINT Oi I~ ro Y OR MORE (HOVE ME ipP 'r,.~ i ~. , i{ a ~ ] I I \\ \ 'O~ \ ^^%E • ql9 W ' -r LEVEL BELOtY THE BDTTON OF' ME IXGVATNN. THE MWNRi IN WHICH ME WATER IS FIEVATKIN OF ME PIPES IN WVNlCE OF SPILLWAY CONSTRUCTIOI $p IHAL ', 1A 1 \ I 'r ]9 4F 17'4 dP ~\ ~ REMOVED SNAll BE SUCH THAT ME EXGVATON BOTTOM WO $DESLOPES ARE THE SRLLWAT PIPES CAN BE INSTN.IID IN A TRENCH WNdiION. ONCE '~ , 41 I 0 0.001 \ ' V THE FlLL 5 BROUGHT UP i0 ABOVE ME 70P OF PIPES, ME PIPE = t ~ \ _ ~ .' \ (V STABLE, TRENCHES SHWID THEN BE EXGYAlEO FOt IN$I/LUTKIN OF ME RPES. ~S LL AA A}° /~~ ] ~ ~ -' ~ ~ N LLLa~xas lx< yE~ ,~ I 7. IF SEEPAGE OR FlAW OCCURS IN OR ALONG M PIPE AlldlNENi, CR,UL T D BD„'. "~• C I \ ~ \ OUTLET SIRUCNRE MATERIAL SPECIIIICA110NS GRWNOwAiER coNFRa WILL BE xEC£ssARr. Mrs couLO wYOLYE }~~~ \, `. I :'~ ~ PUMPNG (OR SiREN% pNERSION, ETC.) OEPENONG Ox ME iOPOGRWNY. _ nk.~, 'M1 I.U:.' `, 410 I/ ILL- 1 T I. ME 47' RCP WRET BWREL SHALLL BE CUSS IY RCP, MODIFIED BELL IMO SPIGOT, SINCE li N NECESSAR/ i0 'MORN N A b2f CCNODON, MK SITW.DCH ` $PHON NUOWNl MEEnNL ME REOUTAEMEMS OF ASTM Ci6-UTEST. DIE PIPE SHAL HAVE CONFINED M1Y REOURE USE Of LEAN CONCRETE BACINU, RO'NIBIF FlL4 ETC. N 4 (SEE DRAIy SNER Po-4C) 4 0-PoNG RUBBER CASNR JONfl MEEDNG WTM C-MS-UlEST. DIE PIPE JDINI$ SHAL ESiIBUSN sI1BGPA0E CONdilONS WIiWIE FOR SDII 1YPE BIOKFILL ` ~ \ \\\\A 4PHON wvE • 419.00 PERWNENT'PppL N BE ttPE A-4. PLACEMENT, 1 ~ NORMAL PpOL • EL 419.Op I +~+' + + ,_ C 2. ME SiRUCTURN p61CN FOR ME fi~.fi~ NTERNIL DIMENSpNS RSER BO% WIM 7. PRIOR i0 INSTAWDON, $VIX',RIDE CONOITN]NS ALONG ME SPILLWAY I PRETAA R5ER OLDLR STRURUAE ~'~~,' A t EXTENDED &SE SHALL RE BY OMERS PAgR TO ORDERING 1HE STRUCNRFS, ME PIPE SHOULD BE EYALGIED Bt THE ON-yIE CEOTECHNKAL ENGNEER i0 I \ %\\ \ A SHWE • SW41tt / I CDNRUCLOA SHALL PAOJIOE ME ENGINEER WIM SNCV OPAWNCS, SPICED BY A P.E 155E55 WHEMER SIIIIWIE SEWING LONdDONS EXBI AT ME WBCRADE \ ~ wRRN11 dNEN516N5 6 R. • 6 R--'- ~ gbIMEM / I REGSIEREO N NORix GAOUNA FOR RMEW. LEVEL. SHOULD SpR OR OMERWTSE UNSUITABLE CONOIDONS [IE \ i0P Ci RISER • 171.53'---'-~ 'FOREBAY i / , ENCOUNTERED ALONG ME PNE AUGNMEMS, MESE LUTERWS SHWlO BE PLYERT Olli (47'4 p-RING RCP) 411.]0 Q 1. ME LASER BOx OViI£T SERUC1I11S SHALL ~ f+kO.1Dm WOH STEPS 16' Ox CENTER UNDERCUT AS DNECTED BY ME GEOIECHNIGL ENGINEER. ME UNDERCUT ,` V ~ ~~ (SEE DE1Nl SNER PD-4Bj r STEPS SH4LL BE FRONDED ON ME IXNER WALL DF ME PoSER BOX. STEPS SW11 ~ IN WTE0.1A15 SHALL BE REPVOED WITH IDE01URlT COMPACTED SiRUCNRN. , YC.~R (r) ACCORDANCE WTM NCWT STD. 840.66, PIFASE REFEN 10 $HER PO-4B FOR LOGiKJIK ~ LEAN CONCRETE OR LLOWABIE FlLL AS pIPEC1Ep B! ME ON-511E ` j `\ _\ I ^^FfF.. `n_ k ~// ' a ME RSER STEPS, CEOTECXNILAL GRGNEER. + I \ 7 _ `~~_____ ' , / / ' I \ ~ 4, IN ORDER i0 HDp PROTECL ME SOIL $UBCRAOE FADN ORERORADON • ~ I \i I \ -- - // 4, ME 10'IaIOW.]t' MILK CONCRETE AND-FLOTAINN BLOCK PoR WATER pLLWtt PoNO a` ~ \ I\ ~ Ig \ ` / r H SHNL BE PREGST AS ME E%1ENDE0 BASE G ME PoSFA BOX WRNG FABRIGTId1 (~ TO IXPOSURE RNNFALE SEEPAGE WO RURROFE) BEFORE THE CRADLE I '. t5 ~ MF PRECAST BASE SHVL BE INCWDEO W DAFT pF iNE SHOP DPAWNCS 11141 WILL BE GN BE POURED, li B STRONGLY RE[OMMENOEO Du7 A ]' i0 4• MILK II \ \. `~ /7 \ \ \ --_-- ' / A I / / CONCREE MUD NAT BE POURED OVER ME SUBGPADE ONCE li 6 a ~ SUBMNTEO ro ME ENGINEER FIXt RENEW (sEE I1E4 7 IBOVE). WpRO7E0 BT ME ON SIZE GEOTECHNICIL ENGINEER ME MUD MAi WILL ~., ~ ? I WW6E • \ / ~- O A150 PRINIOE REARING FOR ME BLCCNS iH4t 1EMPORWILY SUPPORT THE 1 ~ - 5. FALH PoSER BO% JOIM DESIGN SHALL CONFORM i0 ASM L-47B ME JOINTS SHNL I I ~ -_-,_ 419. 171 AOWTIC SKEV B.Tj '~jl O SPILLWAY PIPE UNTIL ME LPAJILE CW BE PWRED. ME MRHOD DF I PoND -- ( E ' -- - BE SEALED USING BUTYL RUBBER SFALWi CONFMMING i0 ASTY-990. ME CONTRALroR BLOLIf SUPPoAT i0ft ME PIPE PROPOSED BY fHE CONDUCTOR SHOULD BE ( NCp^T a5S '0 ~ RAH \ ~~` I T~ \ \ -- TO SIQPEWRON CL. 419.0 i0 L~ /Ii.p 41 ` L\V SHALL PIAGE JOINTS ON BOM ME NSIpE IND WTSIOE WM NON-SHRINK CROUP. - ALOE /MNNTENWLE SUBMITTED i0 ME JOHN A, MGDU15 COMPANY i0R APPRINAL 8 W 17' T;IX ~ ~ W \ ~. / / _ ~ ~I E£ TNC ~ PO d0. EASEMENT M \ qKy M PR iPo R % FRWA R tt 1 HA A ! \`` \ N e. E ELAS SE Po SIRUCNAE 0 iE OUW POND I SHALL YE 5. FILL 114TERUL IAU[ENT TO TIH 47'4 0-RING OUTLET BWREI$ SHALL L ~ - • !2/ \ - W / SNIPPING WEIGHT OF 4&425 IBS. THE SIPUCNRE WEIGHT SHLL BE ME SHIPPNG "^x" - - ~. ;W MEET THE SPECIFIGMNS USTED IN ITEMS I MRWGN ] IN ME SECiNIN I` \ _ O BIOCNOURD iAOMLME GRJSSMSiN11CNRE WEIGHLNMNENFCRIAAIMIN SHALL BEOSMO'M: TIRED 'BERN SOIL k COMPACDON SPECOIGDONS' ME CONIFACroR SHNL r ,.N ~ It ~ ,~~Y ~ ~' I '' \ -\CO ~R' LADE MIN ___ , ~~ ``/ I ~ PAY SPECLLL ATTENnpN i0 THE COMPACTON EFFORTS HONG ME PIPES i0 I -,~~ \ \ "- )- - ON THE SHOP DRAWINGS SWMIliEO r0 ME ENdNEFA i0R RENEW. ENSURE THAI AIL SPACES UNDER Wp AAIACEHi TO ME PIPES WE FILLED f- I ~ \ \ 3 wDN PRDPERLT cwPACrzo wnRMA r '~ r, A r a, ~ v ~ _ _ _ 4 ~ I 7. PRIOR i0 PAPERING, ME CONTRACTOR SW11 SUBMIT TRASH RMD( SHOP DAAWINOS ! ( - I~. f~l l \ \ 47 // I -Q ro ME ENGINEER FOA WPROVN. CONTRACTOR SHALL ENSURE THAT W ACCESS HATCH ~, J` I$ PRGNpED WITHIN ME TiNSH RICK (SEE CE1NL FOR LOGIgN) RUT WLL NLOW FOR TESTING OF TI'IE EM VaNISdQnWl I I 4 i Y ~ .~ ." ~ ~,'C ~., ^:~ ' \ f ~ I` _, a FUMAE MVINENWLE ACCESS. CONTRACTOR SHALL IKSO PROWOE A CHWN WO LOCK 1 Y I,I' Q FOR SECURING THE ACCESS HATCH I. fESDNG Di ME NEW FILL MATERULS SH4ll BE RRFORLIEO i0 VERIFY ~ } I ~ > ` ~ f 17+ • ^J ,IIr TIUi ME RECOMMENDED IEYEL OF CWPACDON I$ ACHIEVED DUAIHL / ..~ $ ~~ ~ - C k4 M..° rfiCOS NE r,A rx. `YJMa ) '~ / d B. .LLL PoUREp CONCRETE SHALL BE MINIMUM 70W P51 (26 DAY) UNLESS OiNERwSE CONSDRUCTON. MEREFOAE ONE DENSITY TEST S1WL BE PERFORMED FpR ' ~ (Y1 NOroO. EVERY 7,SW SONRE RR OF WU FOR EVER! UR pF FAL I If I I ,_ ~ \ , ~,', ~`" l ~~- l U 2 A O xaG RCP CN _-__ / E%ISTINO 20O' i I Q 9. GEOTEA111E UB.RIC FOR ME 42-NCH WTLR BWAEL JOINR SHALL BE AMOCO SME 7. lESTNO WILL BE REQUIRED ALONG ME 47' 0-RING WRR HWREL AI 'COA4'91'iE G At9. jSEE JCAL - - WKE PLAYER 1 N 455] POITPAOPOFNE NON-WN7VEN NEEOIE PJNCNEO W WPAOJED EWIl (NON-WOVEN A FREQUENCY OF ONE TEST PER 25 LL Di PIPE ffR VEATIGL FOOT OF ~ l ~ ~ °~ „FW'EFi FY~wTCj-j',Rk`IA5 k 1,3+LO ~ R1D4i OF WAY T I A I O FABRIC) FlLL - ( `' , ~yW Edts''"'a KE 'Aa^'Pr~~'BSAY.. . ._ ___~ '' I > 10. WATER ODUItt PORO EMEfW;ENCY DAAw00WN FOR THE POND SNNL BE ACHIEVED 'A --T•bND II W NA AN 6'4 RUG VALVE. iNE YALYE SHALL BE A MhN 5111E BZO X-CENTRIC YNYE OR STATEMENT OF RESPONSBRIIY: ~„~'W" TRAk 45CJfi tOW'R ('YiN'RA;,E4H Nx:E55/MVNRHWCE '' A Z WPROVED FOU4L. iH6 VN,K 5 IN ACCDADWCC WIM AWWA C-504 SEC. 5.5. ME NL REOUIREO WlNTEN4NCE WD INSPECTNINS a MI5 FAdUTY 51NLL BE 1 .4, §u.L. MNN7ASN A 27 UbpT RB D DLR'R _ ~ y FASE4EW I I VKVE $HKL BE LOCATED WTHIN THE fi' X 6~ PoSER STAIICNRE, Wp SHN1 BE ME RESPONSIBWtt D< THE O'WNER, PER ME E%EW1E0 OPEAArgN /Np } f . .IGL'$` ryi''ptky;[EA ^,F ExAtwG "OWER I U1 MVNTENWLE AGREEMENT FOR 1x15 U[IUtt. "`"'.".,~_ NS:J:) x' '~, ~ OPERWIE FAON i0P OF STRUCTURE VU A HWDYR+EEL (SEE GRAIL SHER PD-4B). ~~^ -_- ^*. Y ~ - ti C 11. ME 17'4 dP OVRR PIPE SNAIL BE GWKD Op ME UFSiREUI ENO WITH A MRAL Y^ ~ ~Y~~ '- „• 4}~ L __________ _~' t 3 ORIFICE PULE. ME PUR SHALL BE 16':1611/7' (GIIVW12ED) Wp $HNL HAVE A ]Y -~-., N ONFlCE AT ME BORON. RUSE REFER iO DRNL SHEET PO-AC FOR WDInONAL r .iD% ~,. " =m : Y ' ~ y-. , ~~, ,rq ,G r'^" ". ~ R ~' . S~FIY ~ I I `I INFORWiION. I Q (PERENNML) I ____________ I ' C N d 3 ~' ~`~- ~'~~ I 'T''"~ "ir- m 0 ~ WATER QUALITY PO o D #4 PLAN VIE1V I 1 1 1 1 1 I IA_ _ ~ ~~ l E%ISTI~JG WOOOSLINE L GRAPHIC SCALE b 0 5 10 60 Z yO S 1 Ineh 50 h FINAL DRAAING - NDT RELEASED FOR CONSTRllCTION • • BRIAR CHAPEL NEW-05043 B. IHNATOLYA, EI 10/16/2007 Stage-Storage Function Project Name: Briar Chapel Designer: B. Ihnatolya, EI Job Number: NEW-05043 Date: 10/ 15/2007 Average Incremental Accumulated Estimated Contour Contour Contour Contour Stage Contour Stage Area Area Volume Volume w/ S-S Fxn (feet) (feet) (SFl (SF) (CF) (CFl (feed 419.0 0.0 36163 420.0 1.0 38543 37353 37353 37353 1.00 422.0 3.0 43604 41074 82147 119500 2.96 424.0 5.0 48782 46193 92386 211886 5.04 Storage vs. Stage 2soooo 200000 10752 y = 37188x ~ ~ 50000 R2 = 0.9998 m rn 0 100000 50000 0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Stage (feet) Ks = 37188 b = 1.0752 • BRIAR CHAPEL NEW-05043 • _> Stage -Storage Function Ks= 37188 b = 1.0752 Zo = 419 Elevation _Stora e [feet] [cfJ [acre-fey 419 0 0.000 419.2 6590 0.151 419.4 13885 0.319 419.6 21472 0.493 419.8 29255 0.672 420 37188 0.854 420.2 45242 1.039 420.4 53397 1.226 420.6 61641 1.415 420.8 69964 1.606 421 78356 1.799 421.2 86811 1.993 421.4 95325 2.188 421.6 103892 2.385 421.8 112509 2.583 422 121172 2.782 422.2 129879 2.982 422.4 138627 3.182 422.6 147414 3.384 422.8 156238 3.587 • 423 165096 3.790 423.2 173988 3.994 423.4 182912 4.199 423.6 191867 4.405 423.8 200851 4.611 424 209863 4.818 • B. IHNATOLYA, EI 10/ 16/2007 • Type.... Outlet Input Data Paqe 1.01 Name.... WQ Pond #9 File.... X:\Projects\NEW\NEW-05043\Storm\Construction Drawings\WQPOND#4-REVISED.PPW Title... Project Date: 9/27/2007 Project Engineer: Beth Ihnatolya, EI Project Title: Briar Chapel - WQ Pond #9 Project Comments: REQUESTED POND WS ELEVATIONS: Min. Elev.= 419.00 ft Increment = .20 ft Max. Elev.= 424.00 ft OUTLET CONNECTIVITY ---> Forward Flow Only (Upstream to DnStream) <--- Reverse Flow Only (DnStream to Upstream) <---> Forward and Reverse Both Allowed Structure No. Outfall E1, ft E2, ft Weir-Rectangular ES ---> TW 422.950 924.000 Orifice-Circular OR ---> TW 419.000 429.000 Inlet Box RI ---> BA 421.550 424.000 Culvert-Circular BA ---> TW 414.300 924.000 TW SETUP, DS Channel • • S/N: 621701207003 The John R. McAdams Company PondPack Ver. 8.0058 Time: 9:03 AM Date: 10/17/2007 Type.... Outlet Input Data Page 1.02 Name.... WQ Pond #4 File.... X:\Projects\NEW\NEW-05093\Storm\Construction Drawings\WQPOND#4-REVISED.PPW Title... Project Date: 9/27/2007 Project Engineer: Beth Ihnatolya, EI Project Title: Briar Chapel - WQ Pond #4 • Project Comments: OUTLET STRUCTURE INPUT DATA Structure ID Structure Type # of Openings Crest Elev. weir Length Weir Coeff. ES Weir-Rectangular 1 422.95 ft 30.00 ft 3.000000 Weir TW effects (Use adjustment equation) Structure ID = OR Structure Type = Orifice-Circular ------------------------------------ # of Openings = 1 Invert Elev. = 419.00 ft Diameter = .2500 ft Orifice Coeff. _ .600 Structure ID = RI Structure Type = Inlet Box ----------------- # of Openings ------------- 1 ------ • Invert Elev. 421.55 ft Orifice Area 36.0000 sq.ft Orifice Coeff. _ .600 Weir Length = 29.00 ft Weir Coeff. = 3.000 K, Submerged = .000 K, Reverse = 1.000 Kb, Barrel = .000000 (per ft of full flow) Barrel Length = .00 ft Mannings n = .0000 • S/N: 621701207003 The John R. McAdams Company PondPack Ver. 8.0058 Time: 9:03 AM Date: 10/17/2007 • Type.... Outlet Input Data Name.... WQ Pond #9 Page 1.03 File.... X:\Projects\NEW\NEW-05043\Storm\Construction Drawings\WQPOND#4-REVISED.PPW Title... Project Date: 9/27/2007 Project Engineer: Beth Ihnatolya, EI Project Title: Briar Chapel - WQ Pond #4 Project Comments: OUTLET STRUCTURE INPUT DATA Structure ID = BA Structure Type ----------------- = Culvert-Circular ------------------- No. Barrels = 1 Barrel Diameter = 3.5000 ft Upstream Invert = 914.30 ft Dnstream Invert = 414.00 ft Horiz. Length = 54.00 ft Barrel Length = 54.00 ft Barrel Slope = .00556 ft/ft OUTLET CONTROL DATA... Mannings n = .0130 Ke = .5000 Kb = .005885 Kr = .5000 HW Convergence = .001 (forward entrance loss) (per ft of full flow) (reverse entrance loss) +/- ft INLET CONTROL DATA... Equati on form = 1 Inlet Control K = .0098 Inlet Control M = 2.0000 Inlet Control c = .03980 Inlet Control Y = .6700 T1 ratio (HW/D) = 1.157 T2 ratio (HW/D) = 1.309 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 = 418.35 ft ---> Flow = 63.00 cfs At T2 Elev = 918.86 ft ---> Flow = 72.00 cfs S/N: 621701207003 The John R. McAdams Company PondPack Ver. 8.0058 Time: 9:03 AM Date: 10/17/2007 • Type.... Outlet Input Data Name.... WQ Pond #4 Page 1.04 File.... X:\Projects\NEW\NEW-05043\Storm\Construction Drawings\WQPOND#4-REVISED.PPW Title... Project Date: 9/27/2007 Project Engineer: Beth Ihnatolya, EI Project Title: Briar Chapel - WQ Pond #4 Project Comments: OUTLET STRUCTURE INPUT DATA Structure ID = TW Structure Type = TW SETUP, DS Channel ------------------------------------ FREE OUTFACE CONDITIONS SPECIFIED CONVERGENCE TOLERANCES ... Maximum Iterations= 30 Min. TW tolerance = .O1 ft Max. TW tolerance = .O1 ft Min. HW tolerance = .O1 ft Max. HW tolerance = .O1 ft Min. Q tolerance = .10 cfs Max. Q tolerance = .10 cfs • • S/N: 621701207003 The John R. McAdams Company PondPack Ver. 8.0058 Time: 9:03 AM Date: 10/17/2007 • • • Type.... Composite Rating Curve Name.... WQ Pond #4 Page l.ll File.... X:\Projects\NEW\NEW-05093\Storm\Construction Drawings\WQPOND#9-REVISED.PPW Title... Project Date: 9/27/2007 Project Engineer: Beth Ihnatolya, EI Project Title: Briar Chapel - WQ Pond #4 Project Comments: WS Elev, Total Q Elev. Q ft cfs -------- 419.00 ------- .00 419.20 .06 419.40 .12 419.60 .16 419.80 .19 420.00 .22 420.20 .24 920.40 .27 920.60 .29 920.80 .31 921.00 .32 421.20 .34 421.40 .36 421.55 .37 421.60 1.18 421.80 9.39 422.00 22.14 422.20 38.15 422.40 56.85 422.60 77.91 922.80 101.08 922.95 121.65 923.00 123.14 423.20 135.30 423.40 153.09 423.60 174.93 423.80 200.12 429.00 228.23 S/N: 621701207003 PondPack Ver. 8.0058 ***** COMPOSITE OUTFLOW SUMMARY **** -------- Converge TW Elev Error ft +/-ft Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Free Outfall Notes ------------------------- Contributing Structures (no Q: ES,OR,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES, RI, BA) OR (no Q: ES, RI, BA) OR (no Q: ES, RI, BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES,RI,BA) OR (no Q: ES, RI, BA) OR, RI, BA (no Q: ES) OR,RI,BA (no Q: ES) OR, RI, BA (no Q: ES) OR, RI, BA (no Q: ES) OR, RI, BA (no Q: ES) OR, RI, BA (no Q: ES) OR, RI, BA (no Q: ES) OR, RI, BA (no Q: ES) ES, OR, RI, BA ES, OR, RI, BA ES, OR, RI, BA ES, OR, RI, BA ES, OR, RI, BA ES, OR,RI,BA The John R. McAdams Company Time: 9:03 AM Date: 10/17/2007 HMS * Summary of Results for WQ Pond #4 • Project NEW-05043 Start of Run 07Ju102 0000 End of Run 07Ju103 0000 Execution Time 17Oct07 0849 Run Name 1-Yr Post Rev • Computed Results Basin Model Post-Development-Rev Met. Model 1-Year Storm Control Specs 1 Min dT Peak Inflow 64.049 (efs) Date/Time of Peak Inflow 07 Jul 02 1157 Peak Outflow 1.2596 (efs) Date/Time of Peak Outflow 07 Jul 02 1720 Total Inflow 1.38 (in) Peak Storage 2.3869(ac-f t) Total Outflow 1.38 (in) Peak Elevation 421.60 (f t) • HMS * Summary of Results for WQ Pond #4 • Project NEW-05043 Start of Run 07Ju102 0000 End of Run 07Ju103 0000 Execution Time 17Oct07 0850 Run Name 10-Yr Post Rev • Basin Model : Post-Development-Rev Met. Model 10-Year Storm Control Specs 1 Min dT Computed Results Peak Inflow 192.71 (cfs) Peak Outflow 67.029 (cfs) Total inflow 3.42 (in) Total Outflow 3.42 (in) Date/Time of Peak Inflow 07 Jul 02 1204 Date/Time of Peak Outflow 07 Jul 02 1212 Peak Storage 3.2796(ac-f t) Peak Elevation 422.50 (f t) • HMS * Summary of Results for WQ Pond #4 • Project NEW-05043 Start of Run 07Ju102 0000 End of Run 07Ju103 0000 Execution Time 17Oct07 0851 Run Name 25-Yr Post Rev • Basin Model Post-Development-Rev Met. Model 25-Year Storm Control Specs 1 Min dT Computed Results Peak Inflow 172.79 (cfs) Peak Outflow 111.57 (cfs) Total Inflow 4.37 (in) Total Outflow 4.37 (in) Date/Time of Peak Inflow 07 Jul 02 1204 Date/Time of Peak Outflow 07 Jul 02 1210 Peak Storage 3.6835 (ac-f t) Peak Elevation 422.90 (f t) • BRIAR CHAPEL 100-YR-SSFXN B. IHNATOLYA, EI NEW-05043 10/17/2007 _> Stage -Storage Function Ks= 37188 b = 1.0752 Zo = 419 Elevation Stora e [feet] [cf] [acre-feet] ~ 419 0 0.000 419.2 6590 0.151 419.4 13885 0.319 419.6 21472 0.493 419.8 29255 0.672 420 37188 0.854 420.2 45242 1.039 420.4 53397 1.226 420.6 61641 1.415 420.8 69964 1.606 421 78356 1.799 421.25 88934 2.042 Elevation __ Storm 421.45 97462 2.237 [feet] [ct] [acre-fee 421.55 101745 2.336 421.55 ~~0 ~~~~~~~~~~~~~~~~~~~ ~~ ~.~~~~~.0..~_ 0000 421.75 110350 2.533 421.75 8527 0.1958 421.95 119002 2.732 421.95 21416 0.4916 422.15 127699 2.932 422.15 30068 0.6903 422.35 136437 3.132 422.35 38764 0.8899 422.55 145214 3.334 422.55 47502 1.0905 422.75 154029 3.536 422.75 56280 1.2920 422.95 162879 3.739 422.95 65094 1.4944 • 423.15 171762 3.943 423.15 73944 1.6975 423.35 180678 4.148 423.35 82828 1.9015 423.55 189625 4.353 423.55 91744 2.1062 423.75 198602 4.559 423.75 100691 2.3116 423.95 207607 4.766 423.95 109668 2.5176 424 209863 4.818 424 118673 2.7244 • • • • Type.... Composite Rating Curve Name.... WQ Pond #4-WC Notes ------ -- Converge ----------- -- ------------ TW Elev Error ft +/-ft Contributing Structures ------ Free -- ----- - Outfall ------------- (no Q: ES, RI ------------ , BA) Free Outfall RI, BA (no Q: ES) Free Outfall RIBA (no Q: ES) Free Outfall RIBA (no Q: ES) Free Outfall RI, BA (no Q: ES) Free Outfall RI, BA (no Q: ES) Free Outfall RI, BA (no Q: ES) Free Outfall RI, BA (no Q: ES) Free Outfall ES, RI, BA Free Outfall ES, RI, BA Free Outfall ES, RI, BA Free Outfall ES,RI,BA Free Outfall ES,RI,BA Free Outfall ES,RI,BA File.... X:\Projects\NEW\NEW-05043\Storm\Construction Drawings\WQPOND#4-REVISED.PPW Title... Project Date: 9/27/2007 Project Engineer: Beth Ihnatolya, EI Project Title: Briar Chapel - WQ Pond #9 Project Comments: ***** COMPOSITE OUTFLOW SUMMARY **** WS Elev, Total Q Elev. Q ft cfs - - -------- 921.55 -- --- .00 921.75 6.94 421.95 18.21 422.15 33.46 422.35 51.52 422.55 72.00 422.75 94.65 422.95 121.19 923.15 131.14 923.35 147.73 423.55 168.69 423.75 193.09 423.95 220.43 424.00 227.71 S/N: 621701207003 PondPack Ver. 8.0058 Page 1.08 I d0-YE~~ ,. STf}C~E- DIS~F1ARCy E cuRV~ . _ The John R. McAdams Company Time: 9:03 AM Date: 10/17/2007 HMS * Summary of Results for WQ Pond #4 • Project NEW-05043 Start of Run 07Ju102 0000 End of Run 07Ju103 0000 Execution Time 17Oct07 0904 Run Name 100-Yr WC Rev • Computed Results Basin Model Worst Case-Rev Met. Model 100-Year Storm Control Specs 1 Min dT Peak inflow 219.25 (efs) Date/Time of Peak Inflow 07 Jul 02 1204 Peak Outflow 157.70 (efs) Date/Time of Peak Outflow 07 Jul 02 1209 Total Inflow 5.86 (in) Peak Storage 1.9991 (ac-f t) Total Outflow 5.86 (in) Peak Elevation 423.45 (f t) • BRIAR CHAPEL Below NWSE B. IHNATOLYA, EI NEW-05043 10/17/2007 Stage-Storage Function • Project Name: Briar Chapel Designed By: B. Ihnatolya, EI Job Number: NEW-05043 Date: 10/15/2007 Contour (feet) Stage (feet) Contour Area (SF) Average Contour Area (SF) Incremental Contour Volume (CF) Accumulated Contour Volume (CF) Estimated Stage w/ S-S Fxn (feet) 413.0 0.0 19559 414.0 1.0 21120 20340 20340 20340 1.02 416.0 3.0 24394 22757 45514 65854 2.92 417.0 4.0 26107 25251 25251 91104 3.90 419.0 6.0 36163 31135 62270 153374 6.22 • Storage vs. Stage tsoooo tsoooo • ~ 4~11C10 1 1151 y = 199s6x U 120000 RZ = 0.9983 ~, ~ooooo ~ soooo w W 60000 40000 20000 0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Stage (feet) Is = 19966 b = 1.1151 • • BRIAR CHAPEL NEW-05043 Storage vs. Stage 35000 30ooa y . 7196.4x1'0 25000 RZ = 0.9999 LL 20000 Of 0 15000 10000 5000 0 0.0 1.0 2.0 3.0 4.0 5.0 Stage (feet) Ks = 7196.4 b = 1.0888 Forebay Stage-Storage Function Project Name: Briar Chapel Designed By: B. Ihnatolya, EI Job Number: NEW-05043 Date: 10/ 15/2007 Contour (feet) Stage (feet) Contour Area (SF) Average Contour Area (SF) Incremental Contour Volume (CF) Accumulated Contour Volume (CF) Estimated Stage w/ S-S Fxn (feet) 413.0 0.0 6896 414.0 1.0 7524 7210 7210 7210 1.00 416.0 3.0 8854 8189 16378 23588 2.98 417.0 4.0 9557 9206 9206 32794 4.03 B. IHNATOLYA, EI 10/ 17/2007 • BRIAR CHAPEL Volume Check B. II-INATOLYA, EI NEW-05043 10/17/2007 BRIAR CHAPEL - WO POND #4 DESIGN I.~ FORET#A3~~EIa+~HE~«R>>`%~ € ..r......w .~ Per NCDENR "StormwaterBest Management Practices ", the forebay volume should equal about 20% of the total basin volume. A. `Vater Quality Pond -Below Normal Pool Volume Volume = 153374 cf B. Forebay Volume Forebay Volume = 32794 cf %Forebay = 21 Impervious Area = 14.52 acres Drainage Area = 27.138 acres Impervious = 51.9% Total Below NP Volume 153374 cf Surface Area 36163 sf Average Depth = 4.24 ft __> From the NCDENR Stormwater BMP Handbook (4/99), the required SA/DA ratio for 85% TSS Removal • in the Piedmont is as follows: 4.0 4.24 5.0 Lower Boundary => 50.0 1.73 1.50 Site % impervious => 51.9 1.79 1.73 1.54 Upper Boundary => 60.0 2.03 1.71 Area Required = 21052 sf Area Provided = 36163 sf YES • BRIAR CHAPEL NEW-05043 1" RUNOFI • Project Name: Checked by: Job Number: Date: B. IHNATOLYA, EI 10/ 16/2007 Average Incremental Accumulated Estimated Contour Contour Contour Contour Stage Contour Stage Area Area Volume Volume w/ S-S Fxn (feet) (feet) (SF) (SF) (CF) (CF) (feet) 419.0 0.0 36]63 420.0 1.0 38543 37353 37353 37353 1.00 422.0 3.0 43604 41074 82147 119500 2.96 424.0 5.0 48782 46193 92386 211886 5.04 • Storage vs. Stage 250000 200000 ~ o~s2 y = 37188x RZ = 0.9998 v 150000 m rn 0 100000 50000 0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Stage (feet) VOLUME CALCULATION SHEET Briar Chapel -Phase IV B. Ihnatolya, EI NEW-05043 10/15/2007 Ks = 37188 b = 1.0752 Calculation of Runoff Volume required for Storage The runoff to the water quality pond for the 1" storm runoff requirement is calculated by simply multiplying the total watershed area draining to the water quality pond times the runoff depth. Total Drainage Area to WQ Pond = 27.98 acres Runoff Depth = 1 inches Therefore, total runoff from precipitation in cLuestion = 101567 CF This amount of runoff must be stored in the pond above normal pool elevation, and be released in a period of two (2) to five (5) days, by an inverted PVC siphon, the invert end of which is set at permanent pool elevation. • BRIAR CHAPEL NEW-05043 • B. IHNATOLYA, EI 10/ 16/2007 Calculation of depth required for runoff storage pool (above normal pool) Normal pool depth (above invert) = 0.00 feet Therefore, depth required above normal pool for storm storage = 2.55 feet 30.55 inches Storage provided at permanent pool depth = 0 CF (calculated) Total storage required for normal + storage pool = 101567 CF Stage (above invert) associated with this storage = 2.55 feet Set crest of principal spillway at stage = 2.55 feet and EL = 421.55 feet • At principal spillway crest, storm pool storage provided = 101745 CF • BRIAR CHAPEL WATER QUALITY POND #4 B. II-1NATOLYA, EI NEW-05043 10/16/2007 • • Drawdown Time = 4.48 da s By comparison, if calculated by the average head over the orifice (assuming average head is half the total depth), the result would be: Average driving head on orifice = 1.213 feet Orifice composite loss coefficient = 0.600 X-Sectional area of 1 - 3" inverted siphon = 0.049 ft2 Q = 0.2603 cfs Drawdown Time =Volume / Flowrate / 86400 (sec/day) Drawdown Time = 4.52 days Inverted Siphon Design Sheet D siphon = No. siphons = Ks = b= Cd siphon = Normal Pool Elevation = Volume @ Normal Pool = Siphon Invert = WSEL @ 1" Runoff Volume = 3 inches 1 37188 1.0752 0.60 419.00 feet 0 CF 419.00 feet 421.55 feet WSEL (feet) Vol. Stored cf) Siphon Flow (cfs) Avg. Flow (cfs) Incr. Vol. (cf) Incr. Time (sec) 421.55 101745 0.367 421.32 92124 0.350 0.359 9622 26820 421.10 82572 0.332 0.341 9552 28026 420.87 73097 0.312 0.322 9475 29435 420.65 63708 0.291 0.302 9390 31114 420.42 54414 0.269 0.280 9293 33165 420.20 45231 0.245 0.257 9183 35755 419.97 36177 0.218 0.231 9054 39181 419.75 27280 0.187 0.202 8897 44040 419.52 18585 0.149 0.168 8695 51807 419.30 10174.5 0.099 0.124 8411 67891 Conclusion : Use 1 - 3.0" Diameter PVC Inverted Siphon to drawdown the accumulated volume from the 1.0 "storm runoff, with a required time of about 4.48 days. • BRIAR CHAPEL WATER QUALITY POND #4 - 12" DIP NEW-05043 `• Anti-Seep Collar Design Sheet This sheet will, given the barrel length of interest and minimum seep collar projection from the barrel, determine the number of anti-seep collars to place along the barrel section, and the expected spacing of the collars. Design Requirements => Anti-seep collars shall increase the flow path along the barrel by 15%. Anti-seep collars shall be spaced a maximum of 14X the minimum collar projection or 25 feet, whichever is less. J. FINCH, PE 7/28/2006 Anti-Seep Collar Design => WQP • Flow Length Min. Calc'd # Max. #~ of ~ Ltse Pond along barrel Projection of collars Spacing collars to Spacing ; Spacing ID (feet) (feet) required (feet) use>` r. (feet) OK? 4 - 12" DIP 39.0 1.50 1.95 21 ` 3.00 13 I'ES Note : If spacing to use is greater than the maximum spacing, add collars until the spacing to use is equal to or less than the maximum spacing allowable for the collar design. Anti-seep collars shall be used under the structural fill portions of all berms/dams unless an approved drainage diaphragm is present at the downstream end of the barrel. • BRIAR CHAPEL NEW-05043 • Input Data =_> Square RiserBarrel Anti-Flotation Calculation Sheet Inside length of riser = Inside width of riser = Wall thickness of riser = Base thickness of riser = Base length of riser = Base width of riser = Inside height of Riser = Concrete unit weight = OD of barrel exiting manhole = Size of drain pipe (if present) _ Trash Rack water displacement = Concrete Present in Riser Structure =_> J. FINCH, PE 7/28/2006 b.0(1 feet 6.00 feet 6.00 inches 8.00 inches 7.00 feet 7.00 feet 6.95 feet 142.0 PCF ~vc~; ~cr~~~~.r~i:s:~,~t:i~w~:~t 52.50 inches nzanh:,)e c,•~t+.e;Ltz: a.; :; ~ :~C'F. 8.0 inches 79.39 CF Total amount of concrete: Base of Riser = 32.667 CF Riser Walls = 90.350 CF Adjust for openings: Opening for barrel = 7.517 CF Opening for drain pipe = 0.175 CF • Total Concrete present, adjusted for openings = 115.326 CF Weight of concrete present = 16376 lbs Amount of water displaced by Riser Structure =_> Displacement by concrete = 115.326 CF Displacement by open air in riser = 250.200 CF Displacement by trash rack = 79.390 CF Total water displaced by riser/barrel structure = 444.916 CF Weight of water displaced = 27763 lbs Calculate amount of concrete to be added to riser =_> Safety factor to use = 1.15 t:xa:::,:r~:;r~+ ~. j :;r laigl:~~r) Must add = 15551 lbs concrete for buoyancy Concrete unit weight for use = 142 PCF (note above observation for NCP concrete) Buoyant weight of this concrete = 79.60 PCF Buoyant, with safety factor applied = 69.22 PCF Therefore, must add = 224.668 CF of concrete Standard based described above = 32.667 CF of concrete • Therefore, base design must have = 257.334 CF of concrete 1 OF 2 BRIAR CHAPEL NEW-05043 • Calculate size of base for riser assembly =_> Length = 10.000 feet Width = 10.00(1 feet Thiclrness = 31.0 inches Concrete Present = 258.333 CF CLIP Check validity of base as designed =_> Total Water Displaced = 670.582 CF Total Concrete Present = 340.992 CF Total Water Displaced = 41844 lbs Total Concrete Present = 48421 lbs Actual safety factor = 1.16 C)IC Results of design => • • Base length = 10.00 feet Base width = 10.00 feet Base Thickness = 31.00 inches CY of concrete total in base = 9.57 CY Concrete unit weight in added base >_ 142 PCF J. FINCH, PE 7/28/2006 2OF2 Briar Chapel-WQ Pond #4 Project # NEW-05043 VELOCITY DISSIPATOR DESIGN ,• Designed By: B. Ihnatolya Velocity Dissipator - WQ Pond #4 NRCD Land Quality Section Pipe Design Entering the following values will provide you with the expected outlet velocity and depth of flow in a pipe, assuming the Mannings roughness number is constant over the entire length of the pipe. flow Q in cfs :67.029 Flow depth (ft) = 2.58 slope S in % :0.556 Outlet velocity (fps) = 8.823 pipe diameter D in in.: 42 Manning number n :0.013 NRCD Land Quality Section NYDOT Dissipator Design Results • Pipe diameter (ft) 3.50 Outlet velocity (fps) 8.82 Apron length (ft) 28.00 AVG DIAM STONE THICKNESS (inches) CLASS (inches) --------- -------- 3 ----- A 9 6 B 22 »13 Borl 22« 23 2 27 Width Calculation WIDTH = La + Do WIDTH=28.0+3.5 WIDTH = 31.5 FEET CONCLUSION Use 14" DIA NCDOT Class `2' Rip Rap 28'L x 31.5'W x 22"Thick •