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Home My WebLink AboutSW8030321_COMPLIANCE_20030702STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE COMPLIANCE EVALUATION INSPECTION DOC DATE- YYYYMMDD state of North Carolina Department of Environment and Natural Resources Wilmington Regional Office Division of Land Resources Land Quality Section Michael F. Easley, Governor William G. Ross Jr., Secretary P4'�'CWED / J JUL 0 2 2003 July 2, 2003 NU FNR NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES NOTICE OF VIOLATIONS OF THE SEDIMENTATION POLLUTION CONTROL ACT CERTIFIED MAIL P 7003 0500 0000 8804 2191 RETURN RECEIPT REQUESTED Coastal Federal Bank Ms. Susan Cooke, Senior V.P. 2619 Oak Street Myrtle Beach SC 29577 Project Name: Coastal Federal Bank - Shallotte, NC Project No: BR-03222 Brunswick County Dear Ms. Cooke: On June 27, 2003, personnel of this office inspected a project located off of SR 1357 in Brunswick County, North Carolina. This inspection was performed to determine compliance with the North Carolina Sedimentation Pollution Control Act of 1973. The inspection revealed a land -disturbing activity of approximately 1.7 acres being conducted. It is our understanding that you and/or your firm are responsible for this land -disturbing activity. The purpose of this letter is to inform you that this activity was found to be in violation of the Act, NCGS 113A-50 to 66, and Title 15A, North Carolina Administrative Code, Chapter 4. If you feel that you are not responsible for the following violations, please notify this office immediately. The violations'that were found are: Failure to conduct a land -disturbing activity in accordance with the provisions of an approved erosion and sedimentation control plan. G.S. 113A-61.1. Silt fence has not been installed per approved plan. The erosion and sedimentation control plan approved by this office on April 14, 2003 must be immediately implemented on the site sufficient to restrain off -site sedimentation, or if that plan can no longer address the field conditions, submit to this office a revised plan that addresses current erosion and sediment control needs. 127 Cardinal Drive Extension, Wilmington, N.C. 28405.3845 Telephone 910-395.3900 Fax 910.350.2004 An Equal Opportunity Affirmative Action Employer Ms.Susan Cooke July 2, 2003 Page Two 2. Failure on a tract of more than one acre, when more than one acre is uncovered, to install sedimentation and erosion control devices sufficient to retain the sediment generated by the land -disturbing activity within the boundaries of the tract during construction upon and development of the tract. G.S. 113A-57(3). Off -site sedientation was observed in adjacent creek. To correct these violations, you must: 1. Install silt fence per approved plan. The initial one day civil penalty could be an assessment of up to $5,000.00. A time period for compliance is not required for this initial one day civil penalty pursuant to NCGS 113A-61.1 (c) and NCGS 113A-64(a)(1). An initial one day civil penalty is being considered for this project. If the violations described in this Notice are not corrected within 5 days following your receipt of this Notice, the Division of Land Resources may take additional appropriate legal action against you pursuant to NCGS 113A-64. That action could be the assessment of additional civil penalties and may result in the initiation of other remedies as prescribed by the Act. If additional civil penalties are assessed for the violations, the amount may be up to $5,000.00 per day for each day of the violation pursuant to NCGS 133A-64(a)(1). If all violations are corrected within the time period specified for compliance, additional civil penalties or legal remedies will not be pursued. Any new land -disturbing activity associated with this project should not begin until the area presently disturbed is brought into compliance with the Act. When corrective actions are complete, you should notify this office so that the work can be inspected. You should not assume that the site is in compliance with the Act until we have so notified you. In addition, once compliance has been achieved, all installed measures must be satisfactorily maintained until development is complete and the site is fully stabilized to avoid further violations of the Act. We solicit your cooperation, and would like to avoid taking further enforcement action. Atthe same time, it is your responsibility to understand and comply with the requirements of the Act. Copies of the relevant statute and administrative rules may be examined at this office or will be sent to you upon request. Should you have questions concerning this Notice or the requirements of the Act, please contact either Kevin Rowland or me at your earliest convenience. Please do not hesitate to contact me regarding any questions you might have about this matter. Sincerely, Daniel Sams, P.E., M.E. Regional Engineer DESlbfr cc: Sedimentation Specialist WiRO-LQS DWQ Supervisor - WiRO D- CD r- 0 v' Q 9 Permit No. 1) a 03a3 zi_/ (to he provided bY DTPQ) State of North Carolina Department of Environment and Natural Resources Division of Water Quality STORMWATER MANAGEMENT PERMIT APPLICATION FORNI WET DETENTION BASIN SUPPLEMENT This form may be photocopied for use as an original DWQ Stormwater Management Plan Review: A complete stormwater management plan submittal includes an application form, a wet detention basin supplement for each basin, design calculations, and plans and specifications showing all basin and outlet structure details. I. PROJECT INFORMATION Project Name:- tJ =; ; - f - FI2 A-L_ 4-/ O- — S4A LLr07-FE. , A<_ Contact Person: _'S6/tS,4rJ C60,G F_ Phone Number: (94Z) 2D5 2lv 7 6 For projects with multiple basins, specify which basin this worksheet applies to: Tyks 1 t'1 �j elevations Basin Bottom Elevation i 0 • s- ft. Permanent Pool Elevation IS-5- ft. Temporary Pool Elevation 141 ? S ft. areas Permanent Pool Surface Area 3 3 O S sq. ft. Drainage Area [ ac. [mpervious Area 0, Cad ac. ;olianes ?ermanent Pool Volume 441 g cu. ft. Cemporary Pool Volume 2.(q & cu. ft. orebav Volume as 0 cu. ft. 7ther parameters ;A/DAI )iameter of Orifice 0, in. )esign Rainfall i O in. )esian TSS Removal 2 G D (floor of the basin) (elevation of the orifice) (elevation of the discharge structure overflow) (water surface area at the orifice elevation) (on -site and off -site drainage to the basin) (on -site and off -site drainage to the basin) (combined volume of main basin and forebav) (volume detained above the permanent pool) (approximately 20% of total volume) (surface area to drainage area ratio from DWO table) (2 to 5 day ternporan, pool draw -down required) (rninimurn 35% required) COO p�7 Footnotes: 1 When using the Division SA/DA tables, the correct SAIDA ratio for permanent pool sizing should be computed based upon the actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non- standard table entries. 2 in the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide .90% TSS removal. The NCDENR 3NIP manual provides design tables for both 85% TSS removal and 90% TSS removal. II. REQUIRED ITEMS CHECKLIST The following checklist outlines design requirements per the Stormwater Best Management Practices Manual (N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code Section: 15 A NCAC 2H ,1008. Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If the applicant has designated an agent in the Stom-iwater Management Permit Application Form, the agent may initial below. If a requirement has not been met, attach justification. Applicants Initials ` r- _ a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet). 1�04 b. The forebay volume is approximately equal to 20% of the basin volume. �`- c. The temporary pool controls runoff from the design storm event. T d. The temporary pool draws down in 2 to 5 days. �-� e. If required, a 30-foot vegetative filter is provided at the outlet'(include non -erosive flow calculations) `r f. The basin length to width ratio is treater than 3:1. g. manent pool are no steeper than 3:1. The basin. side slopes above the per 2` h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail). D'144 i. Vegetative cover above the permanent pool elevation is specified. j. A trash rack or similar device is provided for both the overflow and orifice. k. A recorded drainage easement is provided for each basin including access to nearest right- of-way. m 1. If the basin is used for sediment and erosion control during construction, clean out of the 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. WET 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. This system (check one) Q does 13 does not incorporate a vegetated filter at the outlet. This system (gheck-one)�Q sloes 0 does not incorporate pretreatment other than a forebay. ,.___ ^ ..F,I 4 .. Maintenance activities shall be performed as follows: L After every significant runoff producing rainfall event and at least monthly. a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation, vegetated cover, and General condition. b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within 2 to 5 days as designed. ?. Repair eroded areas immediately, re -seed as necessary to maintain good:.vegetative cover, mow vegetative cover to maintain a maximum height of six inches, and remove trash as needed. 3. Inspect and repair the collection system. (Le. catch basins, piping, swales, riprap, etc.) quarterly to maintain proper functioning. 1. Remove ar,cumulated sediment front the wet detention basin system semi-annually or when depth is reduced to 75% 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 (i.e. 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 an accurate depth reading and .not readily penetrate into accumulated sediments. When the permanent pool depth reads Z. Z5- feet in the main pond, the sediment shall be removed. When the permanent pool depth reads / , 5- feet in the forebay, the sediment shall be removed. BASIN DIAGR.4iVI (fill in the blanks) '7 _ Permanent Pool Elevation Sediment Re oval El. (,Z, . I Bottom Ele ation 6i F- ]i FOREBA.Y Sediment Removal Elevation ill / S ; -------------75% ------------------------------.I- - ---- 1� Bottom Elevation S + 25% 1 TWAIN POND JOTS 04B,6-7 MA1„r„atNF-414 11\J V'+1 d `rON-L� -A-r 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. T. All components of the wet detention basin system shall be maintained in good working, order. 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 D WQ of any problems with the system or prior to any ;hanges to the system or responsible parry. . rint name: - vlsAr� CcOlc.E title: SENtn2 VICE- �rz�� address: i� OA +`1 - 2D5 - 2-4? -:�CQ Signature: Date: - 2 • 03 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. I, Lic�R A Z2Ln (l % , a Notary Public for the State of �� u4 CMG County of do hereby certify that -�(-k tan oC)/LQ- personally appeared before n1e this Ca� day of FLb � �Q�[� CQf. and acImowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness nay hand and official seal, SEAL My commission expires r. -, I— n _.. � nn Pp0A LL of 4 L-78 03 0 3a-J STORMWATER SUBMITTAL REQUIREMENTS DETENTION POND A. Site Plan ✓� 1. Development/Project Name ~� 2. Designer=s seal, signature, name and firm. V., 3. Legend 4. North Arrow 5. Location Map with direction, distance to named streets, NCSR numbers. 6. Scale �T 7. Date ✓ 8. Revision number and date. 9. Original contours, proposed contours, spot elevations, finished floor elevations. ND ID, Existing drainage, including off -site. Provide a map of any offsite areas. 11 Property/Project boundary lines, dimensioned.4 12.. Mean High Water Line, if project is adjacent surface waters. V 13. Drainage easements, catch basins, pipe sizes, inverts. 14. Wetlands delineated, or a note on the plans that none exist. Ponds may not be located in a wetland. 15.' Details of the road, parking, cul-de-sacs, including sidewalk ,curb and gutter.. 16. Drainage area to each pond delineated. ►� 17. Dimensions of the permanent pool. 18 Vegetated filter detail if using 85% TSS. This is NOT a connector ditch. r% 19. Dimensions of the road, parking cul-de-sacs, sidewalks, and curb and gutter. 20. Unit footprint with dimensions and concrete wood deck areas noted.for apartments or condo development. 21. Forebay at each inlet. (Prefer one inlet) 22. Inlets located such that entire pond is used for treatment and no short-circuiting. 23. Pond/forebay section detail with: Bottom elevation Permanent pool elevation PP Storage pool elevation SP Slopes: 3:1 above permanent pool Vegetated shelf located below permanent pool, 6:1 slope, with begin and end elevat ons arQund_main pond. (Not required inside forebay) Forebay bottom elevation, 3:1 slopes :— Forebay weir elevation between PP and DP. 24. Outlet structure detail with t ash rackand orif c size sped ed. imurash rack �— openingsize is 4%3Y1(},Wd 4_WCWI r UV ' r 25 Note on plans that all roof drains must�e r�recJ e oprcke up bye pond. 26. A 11 L:W ratio has been provided for the pond. P —�� Maximum aver pond depth of 6'. (Parts of pond may be deeper -up to 75) 68. Vegetation requirements for pond slopes and wetland species for the 6:1 shelf are 1 isted. w - Weeping Love grass is not suitable for use in North Carolina. _ 2 13Q aYogs /Cjk r, d"'1 • �r i ds c cafz� 5 add � �s 4-6►'�c�lc�Fe �/ � � or. � S cam- P STORMWATER SUBMITTAL REQUIREMENTS DETENTION.POND (cont) B. Calculations 1. 85% or 90% TSS Chart noted. 2. Pond depth. 3. SA/DA ratio calculation. 4. Required surface area at permanent pool. 5. Provided surface area at permanent pool (Based on pond dimensions) 6. Provided surface area at temporary design pool. 7. Required volume calculation. 8. Provided volume calculation. 9. Orifice size based on required V volume, using average head to design pool elevation. 10. Designer-s seal. 11. Built -upon area to each pond. 12. Forebay designed to hold 20% of the permanent pool volume. (Range of 18-22 OK.) 13. Non -erosive flow for 10 yr. storm in the vegetated filter, if using 85% TSS. C. Supporting Documentation 1. Completed permit application and supplement. a. Is the person who signed the landowner or a leasee? Must be landowner. b. All sections and blanks completely filled in. C. Check signature per .1003 (e). Make sure title is provided. d. If agent signs, signatory authorization from owner. e. Wet detention supplement sheet provided. f. Mailing address & phone of applicant- no CIO. ✓, g. Verify water body classification. r 5 - Z5 -Z -j h. Justifications for not meeting a design requirement. 1. If a modification, include Designer=s Certification. No Hand initial design requirements. _ n CLk.5 LX-kz Q. GZ�,P 2. repowd-deed-restrictions 0 1 D CEDa ?10 ZC�)�ZC'3o) �zC�rU L 2 Yt WET DETENTION POND ANALYSIS FILE NAME PROJECT #: SW8 030321 PROJECT NAME: Coastal Federal G:\DATA\WPDATA\WQSkPOND\030321.WK1 REVIEWER: Laurie Munn DATE: 16-May-03 'Receiving Stream: Woodward Branch Class: C SW HQW Drainage Basin: Lumber Index No. 15-25-2-8 Site Area 1.68 acres Drainage Area 7.339 00�square feet Area in Acres 1.68 IMPERVIOUS AREAS Rational C Building 3618.00 square feet 1.00 Parking 24494.00 square feet 1.00 Sidewalks 1195.00 square feet 1.00 square feet square feet square feet TOTAL square square feet Rational Cc= 0.52 SURFACE AREA CALCULATION % IMPERVIOUS 39.96% SA/DA Ratio 4.50% Des: Depth 3 Req. SA 3297 sf TSS: 90 Prov. SA 3:D sf VOLUME CALCULATION * place a "1" in the box if Rational is used Rational ?* FOREBAY Des. Storm 00„ Inches _... . Perm. Pool Volume= 4418 Rv= 0.410 Req, Forebay Volume= 883.6 Bottom 10.5 msl Provided Volume= 990.00 Perm. Pool;3 SQ.. msl Percent= 4°%p Design Pool 14.25 msl Storage met @elev 15.01 msl Elevation Area Inc. Vol. ACC. Vol. Req. Volume504 ; cf 13.50 3309.00 Vol. Prov. at DP ::.....:2696 > cf 14.25 1240.88 1240.88 ORIFICE. CALCULATION Avg. Head = 0.36 ft Q2 Area = 0.72 sq. inches Flow Q2, cfs 0.014 cfs Q5 Area = 0.29 sq. inches Flow Q5, cfs 0.006 cfs Orifice Area 0.44 sq. inches No. of Orifices „ , ., .': Q= 0.009 cfs Diameter, inches 7:. weir H x W in x in Drawdown = 3 3 days Surface Area @DP = 3881.33333 sq. ft. Falling Head Drawdown = 4.9 days COMMENTS Surface Area , Volume and Orifice are within Design Guidelines, COASTAL FEDERAL Shallotte, NC CALCULATIONS AND SUPPORTING MATERIAL FOR STORMWATER DESIGN lIllarch 003 Prepared by: East Coast Engineering Company, P.A. Consulting Engineers Shallotte, North Carolina 28459 Post Office Box 2469 4918 Main Street Office: 910.754,8029 N m O U N N W N @ O Q) m _0 O U LL cu U a IL G U (U U m co D ( (D o 0 O 4 O O 0 0 0 LO CD M CO 0 (D LLB Ln 0 0 Cr) r V V, CV a0 0 W i` i, N M 0 C7 M O Cl O M O O CC 6 M O O O O C) r (1) O n N co Ln (D � N N Q) a a) d Oa O ❑ � X x > IL a_Ir O [7 X > c a °o i l N Lo Q CO Q E X CD II 7 co u Q O X c > .2 o < CL ❑ x + r L) I I .O C m m — O a� o CD Q� E� cu ❑ a I I C a0 �� I I a b o acr m !I L = n b q) ro O a ms o° O Q a Q � L� m Q o a� C7 Q Q) ro Q) Q a\ m crs Qcm m o Q Q) f4 a Q) o cn cLa a) ro 0 c Q ai a°i o L �) cm C 4 0 j O N� L L Q) O 0 { U) W w V Lol Y O N (� N N N N U (ice C C C C.0 U IrP (D I�r CO r CO LO <T cM LO C ) O r 0 00 I� N I --IT O N Ltd CD0C 000 0or C') CV) o O O C) O O 4) Q) E M N N U ro (U b= � � N Lf) O N C C r r r � X X 0- a) a) > > a) O ❑ a_ N a) a) om ) ro cm ro co o O O m v v) v � N N r) E p 7 ,C x U x U lw N_ o �� _ v' C k r U 55 U QQ oa U Q) Q) m r- Q) Q) CV LO U L 00�-TD L 3 ro ro -T3 -0 - T I m o Q) a Q) a a) a) m a) -ro 0 ct 0 0 Q 4 i� ��o�Q��c� East Coast Engineering Company, PA EMN Coastal Federal Forebay Calculations TOTAL POND VOLUME at PERMANENT POOL FOR POND BEFORE FOREBAY DESIGNED (FOR ESTIMATION PURPOSES) 3.0' deoth. 6.1 slope for 10 '. then 3.1 slaoe ELEVATION (FT MSL) SURFACE AREA (SF) INCREMENTAL VOLUME (CF) ACCUMULATIVE VOLUME (CF) 10.5 474 725 725 11.5 975 1459 2183 12.5 1942 2626 4809 13.5 3309 1 2017, OF PERMANENT POOL VOLUME = 961.700 FOREBAY VOLUME at PERMANENT POOL 2:1 slope ELEVATION (FT MSL) SURFACE AREA (SF) INCREMENTAL VOLUME (CF) ACCUMULATIVE VOLUME (CF) 11.5 327 404 404 12.5 480 572 975 13.5 663 POND 1 VOLUME TO FOREBAY COMPARISON FOREBAY 2:1 SLOPE BOTTOM SF 327.14 SURFACE SF 663.11 DEPTH 2 VOLUME 990 POND DEPTH 4 3:1 SLOPE BOTTOM SF 424.79 TOP SF 893.94 DEPTH 2.33 VOLUME 1536 6:1 SLOPE BOTTOM SF 893.94 SURFACE SF 2556.64 DEPTH 1.67 VOLUME 2881 TOTAL POND VOLUME 4418 FOREBAY % OF POND 22.4% Revision Date 2/17/03 ¢z aii >; w C co a E 0 U Q3 C a) C cn C Li 0 IO O U w co ui N C O E `� U')N U-� O � p N N b U) ¢ N ' O p � m N C)v) LL) � C,N ti � a0 T T �o`' Joao o T 11 II I I m a) E Q L Q Q o O 0 CDm a Q -_ Q Lo U cn¢(��° O00 G J [D LL (� ( N co Q b b 00 � U p U r� CD Oi N Q I7 E-) r� N N fl7 LO Q o o a a`ro r II II I I I? E 0 Q Q o O U C) as u5 m CD C) - y Q 'Q) a u CL ca 000 cr)QC7� d Q Q E 0 m U O A L1_ o j 0) N co Q Q cr� O C:) V Q p to W N U) r- T 0 o T 0 o C) o ti ll II I I IZ co m E a Q Q 0 o -~ OCD m Q InLo co mw n. 2 '� a) 000 c/)QC7 E E a) N w E a� LL E W N m L� Q N N LL N o � mQ� moo C (n< o� rn mQ w 6 o } U U co IE CO r p cry co(h m00u rQrT0) b p�bboob b CD �bbo `n p� Q IQC it 11 I I 0- m E o Q Q O 0 U a a) � a Q Q] '7A In U (O ILO Z3 (n °� oL❑❑U)<(D a 9 II II I? li aL1°i E o Q Q o O U a) a1 Q Q) Q ILO I9 O :3 (n 19 Ql II C ❑ ❑ cn Q C7 F- c Cd c� Q ❑ E 0 m U 0 9 II II tZ I I O m m E a v Q Q `0 0 U '. 0) O) C (1) z Q ror vi �ca) U [LO O I- f9 q) ii WE E` m CU to n cv U'a� BCD o O O r r rn co O Il II I� a w (v E O v Q Q O a -� a)Q) U) rn0c Q)� 4% Q [4 [u a N c !� ❑ ❑ co Q d C O C ca Q E 0 U CD c CV N C C LU V) m O U V) m LU DOr Cu > O U N cD N T T L -�t Cl) Cl) O r r T r C C_ N CO N .^ O CD u-) ki CD a N V) N f) N VC -t CD ;— I-- N N N O r 00 0 In �o Li) C. 0 0 C) C Cl O 0 0 0 0 0 Un Ca 0 0 0 0 0 0 (V N N N N N un Ln V) „Q l..L V rIm I~ co T~ to m LD 0) r` M CD ti LD 00 O ul coCN p CO CJ cf3 N Ln Ci cn � C N N N L r Q U c .N CO r N M <t m m m m w U U U U w U O O 00 O 00 O CD O > M N N r O T C r r r r r r r C7) O,-yOLn Cl) CbV- QJ Q a d) Lo uo Lo r— O r, T 0 0 0 0 0 0 0 0 Cn 0 0 0 0 0 o o N (3) N L i M > r M N N N u7 Cj) N (N N N LO LC) Lf) T T T r T T nQ W CNm m in m c�~U 0 m (� U U U IL U U X E r N c? -T f a Cn o mmmmm_im L LL U U U U U Z U C T N M Q1 O T � Cr7fI3(IJ(gC�(n� G'S Pipe Diameter (in.) 12 Type Pipe CPP "n" Value 0.013 Slope 0.0170 Flow Area (SF) 0.7850 Wetted Perimeter (FT.) 3.1400 Hydraulic Radius (FT.) 0.2500 Velocity (FPS) 5.91 Flowrate (CFS) 4.64 MANNING'S FULL FLOW IN PIPE Pipe Diameter (in.) 12 Type Pipe CPP "n" Value 0.013 Slope 0.0050 Flow Area (SF) 0.7850 Wetted Perimeter (FT.) 3.1400 Hydraulic Radius (FT.) 0.2500 Velocity (FPS) 321 Flowrate (CFS) 2.52 Pipe Diameter (in.) 15 Type Pipe CPP "n" Value 0.013 Slope 0.0110 Flow Area (SF) 1.2266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 5.52 Flowrate (CFS) 6.77 MANNING'S FULL FLOW IN PIPE Pipe Diameter (in.) 15 Type Pipe CPP "n" Value 0.013 Slope 0.0470 Flow Area (SF) 1.2266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 11.41 Flowrate (CFS) 14.00 MANNING'S FULL FLOW IN PIPE Pipe Diameter (in.) 15 Type Pipe UP "n" Value 0.013 Slope 0.0190 Flow Area (SF) 12266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 7.26 Flowrate (CFS) 8.90 cti LJ E r• (n 07 CV C) a7 U) U � Q� g o o v >7 h CO r O 00 (O r L" m m OD C, M (p Qom. r N Q Q r r C Q7 ti II II II cu m W) (v E �. (Dr rn � •° U) Q 000c)E 12 GCS MANNING'S FULL FLOW IN PIPE Disharge Pipe Pipe Diameter (in.) 15 Type Pipe CPP "n" Value 0.012 Slope 0.0100 Flow Area (SF) 1.2266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 5.70 Flowrate (CFS) 6.99 01- n A/ \4 t 1 h Iylt•oe� � V J / r ! 11 " ^ I 1::..I% tC'r�; f if f .•F•J '� •� � t.,;r' y - a �, �•;r ,gyp, , h 4' � � ��r) 11 i J ! % � • 1� - ! ! J } 7� AV ,s'' r t 7 * tt >/ /! ,j Itl t � r •1j� t F• I � f� !if ,I! rIf ! It i�"� 3� � 1 4 fJ j / ! O I / i ! J r ! ! / f i ! ;J 41 0 ZII \mil COASTAL FEDERAL Shallotte, NC CALCULATIONS AND SUPPORTING MATERIAL FOR STORMWATER DESIGN Harch ?003 Prepared by: East Coast Engineering Company, P.A. Consulting Engineers Shallolte, North Carolinn 28459 Post Office Box 2469 49.18 Main Street Office: 910.75,L8029 ¢z a� j W N @ W U) c ,0 Q) m C U- U @ r. y U ,c c U d D (D @ co (DD (~D o a Q � O Lo 0 0 `o U) U) U N a s i C? O O UC} CD m 00 (n (,D u7 Lo O O M r Iqr 1�3- N 00 O W >-(� 1- O � O N 00 LO (*7 Q3 40 C) Qom? Ih N cn LO CD M N N Q N C3 Q) CD a oa o 0 @ x x > d a. O X > O ' _ a ° 0 11 CV QLo c Qi o�ll E @� c� Q X > lT O < X + II CO Ql Q Q O a) a o CD O j L a0 a > �� Q u Q) ti °Q ZI Q O > (`• � N ro O p QqQ) 4�Q Q � @ m Q) a \ rp Q3 Q) a � a 7�3 V) rob m c O d L nai O, ° cn ° - Frm � Q' ro ro ro 44rLC/) O O Z cnW 65WvoC c N in Y O z (%% N N N U U V CO V CD r 00 LO Nil M LO CA CA r O O O O Z- N I-- ITO N LO O 0 O 0 6 0 C0 Q O O C'7 O O O NY v ro 'a N Y) U N � � C C r r r � X X C- a� � O = D N 0 O O Q) N N a m a� O Qi 0 N O N_ N_ CL N � E 'D 'O C X X Q) e e ,I II II II II 0 0 N ko 00 'm 'O c N 4 m fi fi 'o-o Q�� a �ro� 0 o m ro U Y o o a> m W CiC'1zU �CcOU¢¢��C'1 Coastal Federal Forebay Calculations TOTAL POND VOLUME at PERMANENT POOL FOR POND BEFORE FOREBAY DESIGNED FOR ESTIMATION PURPOSES � f ' rienth e- 1 clnna fnr 10 ' than 3.1 -,Irma East Coast Engineering Company, PA EMN ELEVATION (FT MSL) SURFACE AREA (SF) INCREMENTAL VOLUME (CF) ACCUMULATIVE VOLUME (CF) 10.5 474 725 725 11.5 975 1459 2183 12.5 1942 2626 4809 13,5 3309 1 20% OF PERMANENT POOL VOLUME = 9bl.70U FOREBAY VOLUME at PERMANENT POOL 2:1 slope ELEVATION (FT MSL) SURFACE AREA (SF) INCREMENTAL VOLUME (CF) ACCUMULATIVE VOLUME (CF) 11.5 327 404 404 12.5 480 572 975 13.5 663 POND 1 VOLUME TO FOREBAY COMPARISON FOREBAY 2:1 SLOPE BOTTOM SF 327.14 SURFACE SF L 663.11 DEPTH 2 VOLUME 990 POND DEPTH 41 3:1 SLOPE BOTTOM SF 424.79 TOP SF 893.94 DEPTH 2.33 VOLUME 1536 6:1 SLOPE BOTTOM SF 893.94 SURFACE SF 2556.64 DEPTH 1.67 VOLUME 2881 TOTAL POND VOLUME 4418 FOREBAY % OF POND 22.4% Revision Date 2/17/03 ¢z CL2 a LLJ N m 0 U W N c 0 cu U (B cU ❑ L (Q a) a) L a) ¢ LL. 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T Q (] T C) Q C) Q CZ E Q Q � 0) CU m m C U Q c e .m cti t a co .- c U m ul a (D aJ 11 0 0 0 co < C7 ►—� � � C� 0 0 Q Q Z d 2 T w C O Q O U N 0 0 U ANSI m O V N p (N r O C 4 N (D N r O CD LO U-) (D (3 N cn N ►n N Lo CD � d O N N N (D r 00 v to U') 0 r- r f- M CL O O O q, r 0 Cl 0 0 0 p 0 0 w O p 0 0 0 O p Q) N N N N N Uf) cep 'n Q a V � r � r N m m �` Cl) 0D Nr �' LO co CN (D r p N O TLo co N N O N Q O) 'gr C r N N N � (D I— .` r C O U c m m r N M "Cr m ❑ �] m U U U U U ca U � ocooaoocop Q > M N N r O r cn J'rr d' N N O r M N Q r CL 0 In p to O 0 O I- r 0 r Il r r O O O O O O O O 'r N O N Lq M > M N N N if1 r r r r Q) N N N N N LO U7 u) Q) Q r r r r r r CL N M CD N 00 M M o m U U U CLU U Lj E r N c? 00 m (L UUUUUZU OJ r N M Or NING'S FULL FLOW IN PIPE Pipe Diameter (in.) 12 Type Pipe CPP "n" Value 0.013 Slope 0.0170 Flow Area (SF) 0.7850 Wetted Perimeter (FT.) 3.1400 Hydraulic Radius (FT.) 0.2500 Velocity (FPS) 5.91 Flowrate (CFS) 4.64 MANNING'S FULL FLOW IN PIPE Pipe Diameter (in.) 12 Type Pipe UP "n" Value 0.013 Slope 0.0050 Flow Area (SF) 0.7850 Wetted Perimeter (FT.) 3.1400 Hydraulic Radius (FT.) 0.2500 Velocity (FPS) 3.21 Flowrate (CFS) 2.52 MANNING'S FULL FLOW IN PIPE Pipe Diameter (in.) 15 Type Pipe CPP "n" Value 0.013 Slope 0.0110 Flow Area (SF) 1,2266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 5.52 Flowrate (CFS) 6.77 MANNING'S FULL FLOW IN PIPE Pipe Diameter (in.) 15 Type Pipe CPP "n" Value 0.013 Slope 0.0470 Flow Area (SF) 1.2266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 11.41 Flowrate (CFS) 14.00 Pipe Diameter (in.) 15 Type Pipe CPP "n" VaIue 0.013 Slope 0.0190 Flow Area (SF) 1.2266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 7.26 Flowrate (CFS) 8.90 q L \ / 11 E < < / § \ \ \ 12 § m cu c 0 �.g ' = a = O /\ ®� a it/ 20 f i 000//ƒ/3� MANNING'S FULL FLOW IN PIPE Disharge Pipe Pipe Diameter (in.) 15 Type Pipe CPP "n" Value 0.012 Slope 0.0100 Flow Area (SF) 12266 Wetted Perimeter (FT.) 3.9250 Hydraulic Radius (FT.) 0.3125 Velocity (FPS) 5.70 Flowrate (CFS) 6.99 4 of 1 , L +t or � .f . F r O 1 ! / 1 LI 1 � i .4s •� /! / If \ , r LI` NARRATIVE for Coastal Federal Shallotte, Brunswick County, NC DESCRIPTION The site is a 1.68-acre tract located on the corner of Smith Avenue (SR 1357) and White Street in Shallotte, NC. The proposed development on the site is 4038 square foot bank building with twenty-eight (28) parking spaces and drive -through teller window. The site is wooded with sandy topsoil and grades ranging from 0.5% to 2.0%. The site will be graded to meet the proposed plans, however care will be taken to leave as many existing trees as possible and incorporate the trees into the proposed landscaping. A portion of site is wetland. A wetland mitigation plan is proposed to fill a portion of the wetland and create a new area of wetland. Construction is scheduled to begin as soon as all permits and approvals are obtained. STORMWATER MEASURES The storrttwater- runoff from the site is estimated using the rational method. The site is not located near SA waters, thus the first inch 0 ") of rainfall is accounted for in the design. The stormwater will collect into one (1) wet detention basin on the site. The stormwater run-off will be directed to the basins by curbed parking, catch basins, roofline gutters, and underground piping. The basin will outlet to the existing natural drainage course on the site that will direct the outflow to the Woodward Branch (C; Sw, HQW) that is in the Lumber River Basin. EROSION CONTROL MEASURES The attached plans and specifications give the requirements for erosion control measures. Silt fence will be located at certain locations on the perimeter of the site and adjacent to wetlands. The silt fence will be installed prior to any land disturbing activity. The runoff will be directed to the wet detention basin during construction of the site. The basin area will be cleared and grubbed and the basin constructed prior to any other land disturbing activity. The temporary diversion swales will direct the runoff to the basin and shall be established prior to the remaining grading activities on the site. Gravel inlet protection will be used around the catch basins until vegetation is established or the area is paved. A gravel construction entrance will be constructed off of White Street. A riprap energy dissipater will be used on the wet detention basin outlet. The grading contractor and the developer wil I provide the maintenance for the erosion control measures. CONSTRUCTION SEQUENCE The Contractor will install the gravel construction entrance prior to beginning any clearing and grading operations. Siit fence and check dams will be installed prior to beginning any clearing and grading operations. The wet detention basin will be constructed immediately after that portion of the site is cleared, and the outlet structure will be installed with outlet piping. Temporary diversion swales will be installed and will direct runoff to the basin during construction. The catch basins and underground piping will be installed and temporary inlet protection will be established. The site will be graded to proposed grades. The run-off will be directed toward the catch basins during the grading process. The parking area will be paved and the temporary inlet protection will be removed. The disturbed areas will be landscaped and seeded upon completion, and as soon as possible. The wet detention basins will be restored to original depth and design grades after completion of all other construction. NARRATIVE for Coastal Federal Shallotte, Brunswick County, NC DESCRIPTION The site is a 1.68-acre tract located on the corner of Smith Avenue (SR 1357) and White Street in Shallotte, NC. The proposed development on the site is 4038 square foot bank building with twenty-eight (28) parking spaces and drive -through teller window. The site is wooded with sandy topsoil and grades ranging from 0.5% to 2.0%. The site will be graded to meet the proposed plans, however care will be taken to leave as many existing trees as possible and incorporate the trees into the proposed landscaping. A portion of site is wetland. A wetland mitigation plan is proposed to fill a portion of the wetland and create a new area of wetland. Construction is scheduled to begin as soon as all permits and approvals are obtained. STORMWATER MEASURES The stormwater runoff from the site is estimated using the rational method. The site is not located near SA waters, thus the first inch (I") of rainfall is accounted for in the design. The stormwater will collect into one (1) wet detention basin on the site. The stormwater run-off will be directed to the basins by curbed parking, catch basins, roofline gutters, and underground piping. The basin will outlet to the existing natural drainage course on the site that will direct the outflow to the Woodward Branch (C, Sw, HQW) that is in the Lumber River Basin. EROSION CONTROL MEASURES The attached plans and specifications give the requirements for erosion control measures. Silt fence will be located at certain locations on the perimeter of the site and adjacent to wetlands. The silt fence will be installed prior to any land disturbing activity. The runoff will be directed to the wet detention basin during construction of the site. The basin area will be cleared and grubbed and the basin constructed prior to any other land disturbing activity. The temporary diversion swales will direct the runoff to the basin and shall be established prior to the remaining grading activities on the site. Gravel inlet protection will be used around the catch basins until vegetation is established or the area is paved. A gravel construction entrance will be constructed off of White Street. A riprap energy dissipater will be used on the wet detention basin outlet. The grading contractor and the developer will provide the maintenance for the erosion control measures. CONSTRUCTION SEQUENCE The Contractor will install the oravel construction entrance prior to beginning any clearing and grading operations. Silt fence and check dams will be installed prior to beginning any clearing and grading operations. The wet detention basin will be constructed immediately after that portion of the site is cleared, and the outlet structure will be installed with outlet piping. Temporary diversion swales will be installed and will direct runoff to the basin during, construction. The catch basins and underground piping will be installed and temporary inlet protection will be established. The site will be graded to proposed grades. The run-off will be directed toward the catch basins during the grading process. The parking area will be paved and the temporary inlet protection will be removed. The disturbed areas will be landscaped and seeded upon completion, and as soon as possible. The wet detention basins will be restored to original depth and design grades after completion of all other construction.