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HomeMy WebLinkAboutSW8041220_COMPLIANCE_20050512STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW 84�4 Ionic./ DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE COMPLIANCE EVALUATION INSPECTION DOC DATE YYYYMMDD STORMWATER DIVISION CODING SHEET NCG PERMITS PERMIT NO. /v DOC TYPE ❑ HISTORICAL FILE ❑ MONITORING REPORTS DOC DATE ❑ YYYYM M DD Permit No. 5GA)V 0 -Pa24-6__ (to be provided hr DING)) State of North Carolina Department of Ei-ivirollim m mice Nattlrxl RCSOL,rccs Division of Water Quality STORMWATER MANAGEMENT PERMIT APPLICA"I'10N FORM WET DETENTION BASIN SUPPLEMENT This form may be photocopied for use as an original QWQStormwater Management Plan Review: A c;oml)lete stormwater management plan submittal includes an application form, a wet detention basin supplement For each basin, design calculations, and plates and specifications showing all basil) and outlet structure details. I. PROJECT INFORNIATION PI- ject 1ti�tlmc: ��%�� �S r'l'J I --- Contact Person:�OSEj'� f jr"i Phone Number: (�) %_- 1=or 1)rojec:ts with multiple basins, spccify which basin this worksheet applies to: Basin Bottom Elevation 1� R 1%.1- mic:ltt 11001 Elevation �'0 ft I Mpor;sry P001 lXvaI.An �- ' U ft (UTOS (floor Qhe basin) (elevar`ion of the orifice) (elevation of the discharge s11-11cture ovc) low) Permanent Pool Surface Area L0 I sq. ft. (wader surface area at Me (Woce elcvcuhm) Drainage Area !1' 1!05 3 ae. (mi-.rite and off -site drainage to the baser)) lmllervious Area 13(-- 3 a S ac. (on -.rite awl off -sire (lr eiincigw ro Me basin) l�r)i1rrJ1('S' PCI-111,lnCn[ fool VollfSlZe f�/i yg� cU. R. (corrrbhwd vor mie of main basin cma` f)rvbav) l erllpOrary P001 VO1LInle cLI. ft. (volume delained above the per'mr -: 1cw pool) F= ,,rebav Volume d S cu. ft. (approximately 2016 of'loml vohme) Orher parameters SAIlJA T (surface area to drailma("e area ratio Trott) D[Vo dahh) Diameter of 0A ice _ �� �G _ in. (? to -5 day temporary pool drem--clown reriuhvd) Design Rainfall / in. UcsiL -l`SS RenlOVal 8-5 %s lrrlirrinrlurr 85r'/n reaerirerll Form WINE Rev 3.99 Oyu I u C 4 RECEIVED FEB 2 3 2005 DWQ PROd # Footnotes: l whell using the Division SAMA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the aC[U2l1 linpervi011S % and permanent pool depth. Linear interpolation should be employed to determine the Correct va1tlC for I1011- standard table entries. 2 In the 20 coastal COUnties, the regUirement for a vegetative filter may be waived if the wet detentioIl basin is designed to provide 90% TSS removal. The NCDi NR BMP manual provides design tables for both 85% TSS removal and 90°/, TSS removal. 11. REQUIRED ITEMS CHECKLIST The following checklist OLr[11neS design requirements per the Stormwater Best N1aMagenient PraCtiCCS M',tIltlal (N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Codc Section: 15 A NCAC 21-1 .1005. Initial in the space provided to indicate the following design requirements have been met and supposing dOCUmentation is attached. if the applicant has designated an agent in the Stormwater Management Permit Application Form, the agent may initial below. If a requirement has not been met, attach justification. Applicants Initials a. b \~ c. d. ADDC-1) ��RFFLEf. W A-1TS- g 11. i. k. r a` The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet). The forebay volume is approximately equal to 20% of the basin volume. The temporary pool controls runoff from the design storm event. The temporary pool draws down in 2 to 5 days. 11'required, a 30-foot vegetative filter is provided at the outlet (include non -erosive HOW calculations) The basin length to width ratio is greater than 3:1. The basin side slopes above the permanent pool are no steeper than 3:1. A submerged and vegetated perimeter shelf with a slope of'6:1 or less (show detail). Vegetative cover above the permanent pool elevation is specified. A trash rack or similar device is provided for both the overflow and orifice. A recorded drainage easement is provided for each basin including access to nearest right- of-way. If -the basin is used for sediment and erosion control during construction, clean out of'111C basin is specified prior to use as a wet detention basin. m. A mechanism is specified which will drain the basin for maintenance or an emergency. III. W 'f DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the vegetated filter if one is provided. 'Phis system (check ogre) does 0 d not incorporate a vegetated filter at the outlet. 'this system (check acre) 0 does does not incorporate pretreatment other than a forebay. Form SWU-102 Rev 3.99 Page 2 of 4 klaintenance activities shall be performed as follows: 4 After every significant runoff producing rainfall event and at least monthly. a. Inspect the wet detention basin system for sediment accwnnulation, erosion, trash accumulation, vegetated cover, and general condition. b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occtI1-s within 2 to 5 days as designed. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, tnnow vegetative cover to maintain a maximum height of six inches, and remove trash as needed. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to matritatn proper functioning. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is reduced to 759/0 of the original design depth (see diagram below). Removed sediment shall be disposed of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality (Le. stockpiling near a wet detention basin or stream, etc.). The measuring device used to determine the sediment elevation shall be such that it will give all accurate depth reading and not rcaddy penetrate into accumulated sediments. When the permanent pool depth reads _.��feet in the main pond, the sediment shall be removed. When the permanent pool depth reads { 3 0ect in the forebay, the sediment shall be removed. Sediment Rea oval El, 710 75 Bottom I:Ir ation- Ci--� 7 %, 1,ORE,BAY BASIN DIAGRAM (fill in the blanks) Permanent Pool Elevation -l--Y6 Sediment Removfl Elevation , ,. a 75% ----------------_------------------------------- -- Bottom Elevation 90,0 25'% IMAIN.NOND Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These plants shall be encouraged to grow along the vegetated shelf and forebay berm. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through the emergency drain shall be minimized to the maximum extent practical. Form SWU-102 Rev 3.99 Page 3 of 4 7. All components of the wet detention basin system shall be maintained in good working order. I acknowledge and agree by my signature below that I am responsible for the performance -of the seven maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Print name:�/C i`-I M Title: OVJI'J6 Address:_ i�,1� �vc'y lJ (e c &W ` 4-,D M iD wf}'c' �/�7� /!1 as-5w Phone: Signature, Date: 1 &-c-E4 3 C 2 :200 Note: The legally responsible party should not be a homeowners association unless more than 50% of.the lots have been sold and a resident of the subdivision has been named the president. !! r EP Gj av N�/�c� �� By_l�,a� I, a Notary Public for the State of _� I'T/� County of 7' do hereby certify that 1 Im Y_ �� lo4l) personally appeared before me this fS day of --P6iE"1'3 tX. 2a65' , and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, RI WFOIPIE My commission expires 3 J'09'v Form SWU-102 Rev 3.99 Page 4 of l WHITE OAK RIVER BASIN Name of Stream Subbasin Stream Index Number Map Number Class Little Ramhorn Branch WOK03 21-4-1 H31SW6 C Little Run WOK03 21-2-1 H31SW5 C Lodge Creek W0703 21-14 H31SEB C Lynch Creek WOK04 21-35-1-4 H32SW9 SA;HQW Main Prong WOK03 21-16-1 H31SE5 C Mairey Branch WOK03 21-3-1 H31SW7 C Margaret Branch WOK02 19-4-3 H29NW9 C;NSW Maria Creek WOK04 21-35-7-13-1 H33SW2 SA;ORW Meadows Branch WOK03 21-5 H31SW9 C Middens Creek WOK04 21-35-7-24 H32SE9 SA;HQW Mile Hammock Bay WOK02 19-41-2 I29SE5 SA;HQW Mill Creek WOK02 19-9 H29SWB SC;NSW Mill Creek WOK02 19-30-1 I29NW8 SA;HQW Mill Creek WOK02 19-39-3-1 I29SW8 SA;HQW Mill Creek WOKO1 19-41-11-1 I30NW7 SA;HQW Mill Creek WOKO1 20-29-1-1 I30NE2 SA;HQW Mill Creek WOK03 21-19 H31SE9 SA;HQW Mill Run WOK02 19-17-7 I29NW5 SC;NSW Mill Swamp WOK02 19-3-1 H28NE5 C;NSW Milldam Branch WOK03 21-3-6 H31SWB C Millis Swamp WOK03 21-3-2 H31SW7 C Millstone Creek WOK02 19-30-3-1 I29SW1 SA;HQW Mingo Creek WOK04 21-35-7-10-3 H33NW9 Sc Mirey Branch WOK02 19-41-5-3 I29SE3 SA;HQW Mirey Branch WOK01 20-7 H30NW7 C Money Island Bay WOK03 20-36-13 I32NW4 SA;HQW Money Island Slough WOK03 20-36-13-1 I32NW4 SA;HQW Money Island Swamp WOK03 21-16-2 H31SE5 C Morgan Bay WOK02 19-18 I29NWG SC;NSW Matt Creek WOK02 19-16-3 I29NE1 C;NSW Muddy Creek WOK02 19-30-2 I29NW8 SA;HQW Mulberry Creek WOK01 20-13 H30SW4 C Mullet Cove WOK05 21-35-7-31 I33NW4 SA;ORW Mullet Gut WOKO1 20-29-2-1 I30NE1 SA;HQW Mundine Branch NEU11 20-6 H29NE6 C Mundine Branch WOKO1 20-6 H29NE6 C NEW RIVER WOK02 19-.(1) H28NW3 C;NSW NEW RIVER WOK02 19-(7) H29SWB SB;NSW NEW RIVER WOK02 19-(10.5) H29SWB SB;HQW,NSW NEW RIVER WOK02 19-(11) I29NW2 SC;HQW,NSW NEW RIVER WOK02 19-(15.5) I29NW2 SC;NSW NEW RIVER WOK02 19-(27) I29NE7 SA;HQW NEWPORT RIVER WOK03 21-(1) H31SW9 C NEWPORT RIVER WOK03 21-(17) H31SE9 SA;HQW Negro Creek WOK05 21-35-7-4 H33SE2 SA;HQW Nelson Bay WOK04 21-35-7-10-(1) H33NW9 SC Nelson Bay WOK04 21-35-7-10-(5) H33NW9 SA;HQW New River Restricted Area 9 1 WOK02 19-31 I29SW2 SC New River Restricted Area 4 2 WOK02 19-37 I29SE4 SC Newby Creek WOK04 21-35-1-8 I32NW3 SA;HQW Newport River Restricted Area (Morehead City WOK03 21-31 I32NW2 SC Harbor) North Fork White Oak River WOKO1 20-2 H29NW6 C North Leopard Creek WOK04 21-35-1-7-2 H32SEB SA;HQW Page 5 of 8 NC DENR - DIVISON OF WATER QUALITY .0312 WHITE OAK RIVER BASIN 2B .0300 Classification Name of Stream Description Class Date Index No. Little Northeast Creek From source to Northeast C;NSW 08/01/91 19-16-2 Creek Horse Swamp From source to Little C;NSW 08/01/91 19-16-2-1 Northeast Creek Rocky Run From source to Little C;NSW 08/01/91 19-16-2-2 Northeast Creek Poplar Creek From source to Little C;NSW 08/01/91 19-16-2-3 Northeast Creek Mart Creek From source to Northeast C;NSW 08/01/91 19-16-3 Creek Northeast Creek From N. C. Hwy.24 to SC;HQW,NSW 08/01/91 19-16-(3.5} downstream side of mouth of Scales Creek Scales Creek From source to Northeast SC;HQW,NSW 08/01/91 19-16-4 Creek Northeast Creek From the downstream side SC;NSW 08/01/91 19-16-(4.5) of mouth of Scales Creek to New River Southwest Creek From source to Mill Run C;NSW 08/01/91 19-17-(O.5) Catherine Lake Creek From Catherine Lake to C;NSW 08/01/91 19-17-1 Southeast Creek Catherine Lake Entire Lake B;NSW 06/01/91 19-17-1-1 Deep Run From source to Southwest C;NSW 08/01/91 19-17-2 Creek Harris Creek From source to Southwest C;NSW 08/01/91 19-17-3 Creek Haws Run From source to Southwest C;NSW 08/01/91 19-17-4 Creek Tank Creek From source to Southwest C;NSW 08/01/91 19-17-5 Creek Hicks Run (Hickory Run) From source to Southwest C;NSW 08/01/91 19-17-6 Creek Southwest Creek From Mill Run to New River C;HQW,NSW 08/01/91 19-17-(6.5) Mill Run From source to Southwest SC;NSW 08/01/91 19-17-7 Creek Morgan Bay Entire Bay SC;NSW 08/01/91 19-18 Lewis Creek From source to New River SC;HQW,NSW 08/01/91 19-19 Wallace Creek From source to New River SB;NSW 08/01/91 19-20 Bearhead Creek From source to Wallace Creek SB;NSW 08/01/91 19-20-1 Beaverdam Creek From source to Wallace Creek SB;NSW 08/01/91 19-20-2 Town Creek From source to New River SC;HQW,NSW 08/01/91 19-21 Parnell Bay Entire Bay SC;NSW 08/01/91 19-22 Cogdels Creek (Coglin Creek) From source to New River SC;NSW 08/01/91 19-23 Frenchs Creek From source to New River SC;NSW 08/01/91 19-24 Jumping Run From source to Frenchs Creek SC;NSW 08/01/91 19-24-1 2 .. T4 Q�N CA ones S° ti 2OQQOF�ss�oti�,?9 SF..AL 7 J 13301 ; c `' 7j D of � RECEIVED APR 2 9 2005 BY:v) USo�rz2d WET POND REQUIREMENTS DRAINAGE AREA = ACRES / SF 4.6658 ACRES/203,241 SQUARE FEET EXISTING AND PROPOSED IMPERVIOUS AREA IN SQUARE FEET: EXISTING ON -SITE BUILDINGS = 800 SF EXISTING ON -SITE STREETS = 2,400 SF PROPOSED NEW BUILDINGS = 48,000 SF PROPOSID NEW STREETS = 85,133 SF TOTAL = 13..6,133 SF I'l.RC1 N"1' IMPERVIOUS { 1) = 136,333/203,241 = 0.67 THEREFORE USE = 70 '% POOL DEP'1'}-I - 4.0' `1'SS = 85`%o (Therefore filter is required) SA/DA `Vo - 136,333/203,241 4.50/,, = (0.0450) !MINIMUM REQUIRED SURFACE. AREA AT 1'1?RMANE-NT P()()L = 0.0450 x 4.6658 ACRES = 0.209961 ACRES = 9,146 SQUARE FFIFT !\MINIMUM REQUIRED VOLUME OF -TEMPORARY POOL (Simple Method -preferred by DWQ) Rv _ 0.05 + 0.009 (70 )=0.68 VOLUME = (1" / 12 in/ft) x 0.68 x 4.6658 x 43,560 SF/ACRE = 11,517 CU13IC FEET' 0 • • 0 0 • • TOTAL BASIN SIZE EI..EVATION IN FT. AREA IN SF. AVERAGE AREA IN SF DEPTH IN FEET SUES -TOTAL STORAGE IN CF "DOTAL. STORAGE IN CF 90 3866 4218 1 4218 91 4570 4215 4946 1 4946 92 5322 9164 5739 l 5739 93 6156 14903 6581 1 6581 94 7014 permanent pool side 21484 94 3132 forebay side 94 total both sides 10146 actual 9146 required 11522 actual 1 1517 required so ok l 11522 temporary pool 1 foot deep 95 12998 1 i I NOTE; THE ABOVE DATA ARE ABSOLUTE VALUES TAKEN FROM 3-1) COMPUTER DRAWINGS • FOREBAY DATA ELEVATION IN FT. AREA IN SF. AVERAGE AREA IN SF DEPTH IN FEET SUB -TOTAL STORAGE 1N ci= TOTAL STORAGE IN CF 90 196 524 1 524 91 852 524 1165 1 1165 92 1478 1689 1842 1 1842 93 2206 3531 2669 1 2669 94 lorebay side 3132 6200 actual 4297 rcquirvd • 0 FOREBAY DATA TOTAL BASIN VOLUME = 21,484 CUBIC FEET FOREBAV VOLUME REQUIRED = 20'%, THEREFORE 0.2 (21,484) = 4,297 CUBIC FEET REQUIRED ACTUAL FOREBAY VOLUME = 6,200 CU131C FEET THEREFORE OK iN`OTE; THE ABOVE DATA ARE ABSOLUTE VALUES TAKEN FROiNI 3-1) COi\IPUTFR DIIAWINGS PERM POOL CALCULATIONS SURFACE AREA PROVIDED FOR I'P = 10,146 SQUARE FEET WHICH 1S GREATER "THAN REQUIRED 9,146 SQUARE FEET AT ELEVATION OF 94,00' (AREA AND VOLUME TAKEN FROM COMPUTER MODELING) TEMP POOL CALCULATIONS NEED AT LEAST11,517 (USING COMPUTER MODELING DATA) CU131C 1' "ET 01' S'I-OIZA(-,I•_ (I l,522 - 11,517 = L00') TIIEREFOR1, TEMP POOL 1.00' 1)E:EP SET ELEVATION OF TEMPORARY POOL rr = 95.00' SURFACE AREA OBTAINED FROM COMPUTER MODELING EQUALS 12,898 SQUARE FEET Gal ELEVATION OF 95.00'. TOTAL VOLUME PROVIDED ABOVE PERM POOL= 11,522 CUBIC FEET WHICH 1S GREATER THAN THE REQUIRED AMOUNT OF 11,517 CU131C FEET 0 ORIFICE SIZING AREA OF 3/4" CIRCULAR ORIFICE = 0.0030079 All FA OF I" CIRCULAR ORIF]CF = 0.0115454 FT, AREA OF 1.5" CIRCULAR ORIFICE = 0,012272 I,'p, AREA OF 2" CIRCULAR ORIFICE = 0.021817 FI" AREA OF 2.25" CIRCULAR ORIFICE, = 0.027612 FT1 AREA OF 2.5" CIRCULAR ORIFICE = 0,034088 FT2 USE REQUIRED VOLUME OF TEMP POOL, NOT ACTUAL VOLUME (USE 11,517 CF) Qz wu = 11,517 - 172800 (SECONDS FOR 2 DAY PERIOD) = 0.066649 CFS (Flo v rate required Fora 2 day draw down) QS[),\). = 11,517 - 432000 (SECONDS FOR 5 DAY PERIOD) = 0.0266597 CFS (Flow rate requires[ tiara 5 da), draw clown) CHOOSE A L50" CIRCULAR ORIFICE HEAD=''/x'I'I-IE DEPTH OFTEMP. POOL OF (1.00 FEET) OR (0.5 FEET') COEFFICIENT USED FOR ORIFICE: ENTRANCE = 0.63 EQUATION USED Q = C* A( 2GII)' Q= 0.63*0.012272*(2*32.2*0.5) '' = 0.04387 CFS TWO DAY DRAW DOWN > VOLUME THROUGH ORIFICE > FIVL' DAY DRAW DOWN Q=0.0 19454 C FS.......... (0.066649>0.04387>0.0266597) "1' I I E It I: I'O R I: O K THEREFORE USE 1.50" ORIFICE WET'DETENTION POND ANALYSIS FILE NAME: PROJECT#: SW8 041220.feb05 PROJECT NAME: Adams Mini Storage S:1WQS1POND1041220.fe1b05.WK1 REVIEWER: DATE: 13-Feb-05 Receiving Stream: Motts Creek Class: C NSW Drainage Basin: White Oak Index No. Site Area 4.67 acres Drainage Area 2 03T.00:' square feet Area in Acres 4.67 IMPERVIOUS AREAS Buildings Parking SW TOTAL SURFACE AREA CALCULATION 48800,00 square feet 85533.00 square feet square feet square feet square feet square feet square feet 001 1-53— jsquare feet Rational C Rational Cc= 0.07 % IMPERVIOUS 6T08% SA/DA Ratio 4,30% Des. Depth 4 Req. SA 8730 sf TSS: 85 Prov. SA sf VOLUME CALCULATION * place a "ll" in the box if Rational is used Rational ?* Des. Storm ': 0) inches Rv= 0.654 Bottom 90 msl Perm. Pool msl Design Pool 95 msl Storage met @elev 94,96 msl ORIFICE CALCULATION FOREBAY Perm. Pool Volume= 21484 Req. Forebay Volume= 42C-6.8 Provided Volume= 6200.00 Percent= 11."c��ii!'28,0%:;; Elevation 94.00 95.00 Area 10146.00 12898.00 .Inc. Vol. 11522.00 Avg. Head = 0.48 ft Q2 Area = 2.77 sq. inches Flow Q2, cfs 0.064 cfs Q5 Area = 1.11 sq. inches Flow Q5, cfs 0.026 cfs Orifice Area 0.79 sq. inches No. of Orifices !;. .1 .1 Q= 0.018 cfs Acc. Vol. 0.00 11522.00 Diameter, inches 1.00! weir H x W in x n Drawdown days Surface Area @DP 12898 sq. ft. jo! Falling Head Drawdown = 10.2 days C: 3.317916667 L= -0.096 COMMENTS Surface Area and Volume are within Design Guidelines. Orificeistoo small