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HomeMy WebLinkAboutSW8040124_HISTORICAL FILE_20040827STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW DOC TYPE ❑ CURRENT PERMIT . ❑ APPROVED PLANS HISTORICAL FILE ❑ COMPLIANCE EVALUATION INSPECTION DOC DATE �Og� YYYYMMDD State Stormwater Management Systems Permit No. SWS O40124 STATE OF NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES DIVISION OF WATER QUALITY STATE STORMWATER MANAGEMENT PERMIT HIGH DENSITY DEVELOPMENT In accordance with the provisions of Article 21 of Chapter 143, General Statutes of North Carolina as amended, and other applicable Laws, Rules, and Regulations PERMISSION IS HEREBY GRANTED TO Allan Rappuhn, Canebreak, L.P. Canebreak Apartments Lullwater Drive, New Hanover County FOR THE construction, operation and maintenance of a wet detention pond in compliance with the provisions of 15A NCAC 2H .1000 (hereafter referred to as the "stormwater rules') and the approved stormwater management plans and specifications and other supporting data as attached and on file with and approved by the Division of Water Quality and considered a part of this permit. This permit shall be effective from the date of issuance until August 27, 2004, and shall be subject to the following specified conditions and limitations: I. DESIGN STANDARDS This permit is effective only with respect to the nature and volume of stormwater described in the application and other supporting data. 2. This stormwater system has been approved for the management of stormwater runoff as described in Section 1.6 on page 3 of this permit. The stormwater control has been designed to handle the runoff from 93,046 square feet of impervious area. 3. The tract will be limited to the amount of built -upon area indicated on page 3 of this permit, and per approved plans. 4. All stormwater collection and treatment systems must be located in either dedicated common areas or recorded easements. The final plats for the project will be recorded showing all such required easements, in accordance with the approved ,'plans. '1 5. The runoff from all built -upon area within the permitted drainage area of this project must'be directed into the permitted stormwater control system. Page 2 of 7 State Stormwater Management Systems Permit No. SW8 040124 6. The following design criteria have been provided in the wet detention pond and must be maintained at design condition: a. Drainage Area, acres: Onsite, ft : Offsite, ft2: b. Total Impervious Surfaces, ft2: C. Design Storm, inches: d. Pond Depth, feet: e. TSS removal efficiency: f. -Permanent Pool Elevation, FMSL: g. Permanent Pool Surface Area, ft2: h. Permitted Storage Volume, ft3: i. Temporary Storage Elevation, FMSL j. Controlling Orifice: k. Permitted Forebay Volume, ft3: I. Receiving Stream/River Basin: m. Stream Index Number: n. Classification of Water Body: II. SCHEDULE OF COMPLIANCE 3.81 165,964 0 93,046 ,10 5.0 90% 35.40 11,067 13,387 36.53 1"O pipe 10,454 Burnt Mill Creek 1 Cape Fear CPF17 18-74-63-2 "C Sw" 1. The stormwater management system shall be constructed in its entirety, vegetated and operational for its intended use prior to the construction of any built -upon surface. 2. During construction, erosion shall be kept to a minimum and any eroded areas of the system will be repaired immediately. 3. The permittee shall at all times provide the operation and maintenance necessary to assure the permitted stormwater system functions at optimum efficiency. The approved Operation and Maintenance Plan must be followed in its entirety and maintenance must occur at the scheduled intervals including, but not limited to: a. Semiannual scheduled inspections (every 6 months). b. Sediment removal. C. Mowing and revegetation of slopes and the vegetated filter. d. Immediate repair of eroded areas. e. Maintenance of all slopes in accordance with approved plans and specifications. f. Debris removal and unclogging of outlet structure, orifice device, flow spreader, catch basins and piping. g. Access to the outlet structure must be available at all times. ;r Page 3 of 7 State Stormwater Management Systems Permit No. SW8 040124 4.. Records of maintenance activities must be kept and made available upon request to authorized personnel of DWQ. The records will indicate the date, activity, name of person performing the work and what actions were taken. 5. Decorative spray fountains will be allowed in the stormwater treatment system, subject to the following criteria: a. The fountain must draw its water from less than 2' below the permanent pool surface. b. Separated units, where the nozzle, pump and intake are connected by tubing, may be used only if they draw water from the surface in the deepest part of the pond. c. The falling water from the fountain must be centered in the pond, away .from the shoreline. d. The maximum horsepower for a fountain in this pond is 118 HP horsepower. 6. The facilities shall be constructed as shown on the approved plans. This permit shall become voidable unless the facilities are constructed in accordance with the conditions of this permit, the approved plans and specifications, and other supporting data. 7. Upon completion of construction, prior to issuance of a Certificate of Occupancy, and prior to operation of this permitted facility, a certification must be received from an appropriate designer for the system installed certifying that the permitted facility has been installed in accordance with this permit, the approved plans and specifications, and other supporting documentation. Any deviations from the approved plans and specifications must be noted on the Certification. A modification may be required for those deviations. 8. If the stormwater system was used as an Erosion Control device, it must be restored to design condition prior to operation as a stormwater treatment device, and priorto occupancy of the facility. 9. Access to the stormwater facilities shall be maintained via appropriate easements at all times. 10. The permittee shall submit to the Director and shall have received approval for revised plans, specifications, and calculations prior to construction, for any modification to the approved plans, including, but not limited to, those listed below: a. Any revision to any item shown on the approved plans, including the stormwater management measures, built -upon area, details, etc. b. Project name change. C. Transfer of ownership. d. Redesign or addition to the approved amount of built -upon area or to the drainage area. e. Fdrther subdivision, acquisition, lease or sale of all or part of the project area. The project area is defined as all property owned by the permittee, for which Sedimentation and Erosion Control Plan approval or a CAMA Major permit was sought. f. 'Filling in, altering, or piping of any vegetative conveyance shown on the approved plan. 11. The permittee shall submit final site layout and grading plans for any permitted future areas shown on the approved plans, prior to construction. 12. A copy of the approved plans and specifications shall be maintained on file by the Permittee for a minimum of ten years from the date of the completion of construction. Page 4of7 State Stormwater Management Systems Permit No. SW8 040124 13. The Director may notify the permittee when the permitted site does not meet one or more of the minimum requirements of the permit. Within the time frame specified`'in the notice, the permittee shall submit a written time schedule to the Director for modifying the site to meet minimum requirements. The permittee shall provide copies of revised plans and certification in writing to the Director that the changes have been made. III. GENERAL CONDITIONS This permit is not transferable except after notice to and approval by the Director. In the event of a change of ownership, or a name change, the permittee must submit a formal permit transfer request to the Division of Water Quality, accompanied by a completed name/ownership change form, documentation from the parties involved, and other supporting materials as may be appropriate. The approval of this request will be considered on its merits and may or may not be approved. The permittee is responsible for compliance with all permit conditions until such time as the Division 'approves the transfer request. 2. Failure to abide by the conditions and limitations contained in this permit may subject the Permittee to enforcement action by the Division of Water Quality, in accordance with North Carolina General Statute 143-215.6A to 143-215.6C. 3. The issuance of this permit does not preclude the Permittee from complying with any and all statutes, rules, regulations, or ordinances, which may be imposed by other government agencies (local, state, and federal) having jurisdiction. 4. In the event that the facilities fail to perform satisfactorily, including the creation of nuisance conditions, the Permittee shall take immediate corrective action, including those as may be required by this Division, such as the construction of additional or replacement stormwater management systems. 5. The permittee grants DENR Staff permission to enter the property during normal business.;hours for the purpose of inspecting all components of the permitted stormwater management facility. 6. The permit may be modified, revoked and reissued or terminated for cause. The filing of a request for a permit modification, revocation and reissuance or termination does not stay any permit condition. 7. Unless specified elsewhere, permanent seeding requirements for the stormwater control must follow the guidelines established in the North Carolina Erosion and Sediment Control Planning and Design Manual. 8. Approved plans and specifications for this project are incorporated by reference and are enforceable parts of the permit. 9. The permittee shall notify the Division any name, ownership or mailing address changes within 30 days. Permit issued this the 27th day of August, 2004. NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION Alan W. Klimek, P.E., Director Division of Water Quality By Authority of the Environmental Management Commission Page 5 of 7 McKEAN & A A R C H I T E C T S August 5, 2004 NCDENR Wilmington Regional Office 127 Cardinal Drive Extension Wilmington, NC 28405 (Courier 04-16-33) 910/395-3900 FAX 910/350-2004 Re: Stormwater Application No. SW8 040124 Linda Lewis: TES L L C RECEIVED AUG 0 6 2004 DWQ Included are the revised calculations and plans for the State Sewer Permit for Canebreak Apartments. I f you have any questions. call me at (334) 272-4044. Sincerely, Brice Taylor 2815-B Zelda Road, Montgomery, Alabama 36106, Telephone (334) 2724044, Facsimilie (334) 244-0347 OF WATER Michael F. Easley, Governor p William G. Ross Jr., Secretary North Carolina Department of Environment and Natural Resources Alan W. Klimek, P.E.,Director p Division of Water Quality Coleen H. Sullins, Deputy Director Division of Water Quality March 26, 2004 Mr. Allan Rappuhn, Managing Member Canebreak, LP PO Box 220 Florence, AL 35631 Subject: Request for Additional Information Stormwater Project No. SW8 040124 Canebreak Apartments New Hanover County Dear Mr. Rappuhn: The Wilmington Regional Office received a Stormwater Management Permit Application for Canebreak Apartments on January 20, 2004. A preliminary review of that information has determined that the application is not complete. The following information is needed to continue the stormwater review: 1. Please either delineate all wetlands on site, disturbed or undisturbed, or note on the plans that none exist. 2. Since Mr. Kenneth White is your consultant, and is providing information regarding this application, please complete Section VI on page 4 of the application. 3. Please delineate the single overall drainage area to the pond. It appears from the post -runoff pond data tabulation that only 4.34 acres is draining to the pond, while 5.25 acres has been reported on the supplement and is used in the pond sizing calculations. 4. There appears to be runoff entering this project from the adjacent Manassas and Tatum Family properties, as well as from the single family lots to the south. Please either provide a means for this runoff to bypass the pond, or include these numbers in the pond's drainage area and impervious area at 90% build -out. 5. The runoff from all of the proposed built -upon area, including the backs of all the buildings and access drives, must either'be directed into the pond or a separate engineered treatment system must be provided. It appears from the drainage area sheet that areas 13 and 15, which contain built -upon area, will not be directed into the pond. 6. Please provide a list of wetland species to be planted on the 6:1 shelf. 7. Please add a note to the plans that all roof drainage must be directed to the forebay of the proposed pond. N. C. Division of Water Quality 127 Cardinal Drive Extension (910) 395-3900 Customer Service A*'A Wilmington Regional Office Wilmington. NC 28405 (910) 350-2004 Fax 1 800 623-7748 NCE)ENR Mr. Rappuhn March 26, 2004 Stormwater Application No. SW8 040124 8. Please add a typical building detail showing dimensions, and identifying all covered decks or stairs, sidewalk, patios, etc. 9. Please specify a trash rack for the outlet structure. Maximum openings are 4 inches square. 10. The basin diagram on page 3 of the supplement indicates that the permanent pool elevation is 42.26, while page one of the supplement and the plans report that the permanent pool elevation is 35.40. Please correct and revise. Additionally, the cleanout depths have been reported as elevations instead of depths. Based on a 5.4' deep pond, the cleanout depth is 4.05'. Please make the appropriate corrections and resubmit. Please note that this request for additional information is in response to a preliminary review. The requested information should be received by this Office prior to April 26, 2004, or the application will be returned as incomplete. The return of a project will necessitate resubmittal of all required items, including.the application fee. If you need additional time to submit the information, please mail or fax your request for a time extension to the Division at the address and fax number at the bottom of this letter. The request must indicate the date by which you expect to submit the required information. The Division is allowed 90 days from the receipt of a completed application to issue the permit. The construction of any impervious surfaces, other than a construction entrance under an approved Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject to enforcement action pursuant to NCGS 143-215.6A. Please reference the State assigned project number on all correspondence. Any original documents that need to be revised have been sent to the engineer or agent. All original documents must be returned or new originals must be provided. Copies are not acceptable. If you have any questions concerning this matter please feel free to call me at (910) 395-3900. Sincerely, Linda Lewis Environmental Engineer RSS/arl: S:IWQSISTORMWATIADDINF0120041040124.mar04 cc: Kenneth White, P.E. Linda Lewis Page 2 of 2 OF WArFR Michael F. Easley, Governor William G. Ross Jr., Secretary North Carolina Department of Environment and Natural Resources Alan W. Klimek P.E.,Director Division of Water Quality Coleen H. Sullins, Deputy Director Division of Water Quality March 26, 2004 Mr. Allan Rappuhn, Managing Member Canebreak, LP PO Box 220 Florence, AL 35631 Subject: Request for Additional Information Stormwater Project No. SW8 040124 Canebreak Apartments New Hanover County Dear Mr. Rappuhn: The Wilmington Regional Office received a Stormwater Management Permit Application for Canebreak Apartments on January 20, 2004. A preliminary review of that information has determined that the application is not complete. The following information is needed to continue the stormwater review: 1. Please either delineate all wetlands on site, disturbed or undisturbed, or note on the plans that none exist. 2. Since Mr. Kenneth White is your consultant, and is providing information regarding this application, please complete Section VII on page 4 of the application. 3. Please delineate the single overall- drainage area to the pond. It appears from the post -runoff pond data tabulation that only 4.34 acres is draining to the pond, while 5.25 acres has been reported on the supplement and is used in the pond sizing calculations. 4. There appears to be runoff entering this project from the adjacent Manassas and Tatum Family properties, as well as from the single family lots to the south. Please either provide a means for this runoff to bypass the pond, or include these numbers in the pond's drainage area and impervious area at 90% build -out. 5. The runoff from all of the proposed built -upon area, including the backs of all the buildings and access drives, must either be directed into the pond or a separate engineered treatment system must be provided. It appears from the drainage area sheet that areas 13 and 15, which contain built -upon area, will not be directed into the pond. 6. Please provide a list of wetland species to be planted on the 6:1 shelf. 7. Please add a note to the plans that all roof drainage must be directed to the forebay of the proposed pond. N. C. Division of Water Quality 127 Cardinal Drive Extension (910) 395-3900 Customer Service C* Wilmington Regional Office Wilmington, NC 28405 (910) 350-2004 Fax 1 800 623-7748 iNCDENR Mr. Rappuhn March 26, 2004 Stormwater Aoolication No. SW8 040124 8. Please add a typical building detail showing dimensions, and identifying all covered decks or stairs, sidewalk, patios, etc. 9. Please specify a trash rack for the outlet structure. Maximum openings are 4 inches square. 10. The basin diagram on page 3 of the supplement indicates that the permanent pool elevation is 42.26, while page one of the supplement and the plans report that the permanent pool elevation is 35.40. Please correct and revise. Additionally, the cleanout depths have been reported as elevations instead of depths. Based on a 5.4' deep pond, the cleanout depth is 4.05'. Please make the appropriate corrections and resubmit. Please note that this request for additional information is in response to a preliminary review. The requested information should be received by this Office prior to April 26, 2004, or the application will be returned as incomplete. The return of a project will necessitate resubmittal of all required items, including the application fee. If you need additional time to submit the information, please mail or fax your request for a time extension to the Division at the address and fax number at the bottom of this letter. The request must indicate the date by which you expect to submit the required information. The Division is allowed 90 days from the receipt of a completed application to issue the permit. The construction of any impervious surfaces, other than a construction entrance under an approved Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject to enforcement action pursuant to NCGS 143-215.6A. - Please reference the State assigned project number on all correspondence. Any original documents that need to be revised have been sent to the engineer or agent. All original documents must be returned or new originals must be provided. Copies are not acceptable. If you have any questions concerning this matter please feel free to call me at (910) 395-3900. Sincerely, 04--)z�z" Linda Lewis Environmental Engineer RSSlad: S:IWQSISTORMWATIADDINFO120041040124.mar04 cc: Kenneth White, P.E. Linda Lewis Page 2 of 2 McKEAN A R C H I T E May 6. 2004 NCDENR Wilmington Regional Office 127 Cardinal Drive Extension Wilmington, NC 28405 (Courier 04-16-33) 910/395-3900 FAX 910/350-2004 &A C T S TES .L—L C IMA 112004 Re: Stormwater Application No. SW8 040124 Linda Lewis: Included are the revised forms and plans for the Stat Permit for Canebreaic Apartments. If you have any questions. call me at (334) 272- 4. Sincerely, Bruce Taylor 2815-B Zelda Road, Montgomery, Alabama 36106, Telephone (334) 2724044, Facsimilie (334) 244-0347 Drainage Summary for Canebreak Apartments Located at Lullwater Drive Wilmington, North Carolina I. Project Description The project consists of construction of multi family residential units and associated sitework on 5.25-acre tract located off Lullwater Drive in Wilmington, NC. The project will be constructed in one phase. The site is currently vacant. Construction will include approximately 32 units, drives, water and sewer utilities, and concrete sidewalks. 2. Pre -Construction Site Conditions Site is a relatively flat piece of property with ditches running along the east side of the property. These ditches drain to the NE corner of the property. This water drains from south to north eventually draining into Burnt Mill Creek. 3. Post -Construction Site Conditions Site will have a wetpond located in and discharging to the NE corner of property. The runoff from the site will be piped to this pond, and held in order to provide 90% removal of total suspended solids without a vegetative filter. The ditch running down east side of property will remain and be the discharge point from the wetpond. 4. Soil Erosion and Sedimentation The site will be protected by silt fence on the east, west, south and north property lines. Silt fence will be installed around all storm structures to prevent silt from entering storm drain system. A construction entrance shall be installed to keep dirt to a minimum on Lullwater Drive. Rip Rap will be installed at all discharging headwalls to prevent erosion. The wetpond will be utilized for storage of silt buildup, and will be maintained properly at all times. The site will be sodded and seeded at appropriate time to stabilize all graded areas. RECEIVED AUG 0 6 2004 PRoa# 5�i? 6401Z4 III H+/r,, • �N CA�qO p4' •Frassio SEAL��� � S 026069 IN „»> v 7 5, fm� Canebreak Apartments Wilmington, NC 03-532 Pre Runoff for a 10 Year Rainfall Event Basin Area (Acres) c I Q (cfs Offsite 5.25 0.450 6.50 15.36 Total 15.36 Unrestricted Post Runoff for a 10 Year Rainfall Event Basin Area (Acres) c I Q (cfs Offsite 1.44 0.668 6.50 6.25 Pond 3.81 0.668 6.50 16.54 Total 22.79 Restricted Post Runoff for a 10 Year Rainfall Event Basin Area (Acres) c I Q (cfs) Offsite 1.44 0.668 6.50 6.25 Structure 1" Orifice=0.015 Primary Weir=0.39 NIA 0.41 Total 6.66 Canebreak Apartments Wilmington, NC 03-532 Pre Runoff for a 50 Year Rainfall Event Basin Area (Acres) C I Q cfs Offsite 5.25 0.450 7.50 17.72 Tota 17.72 Post Runoff for a 50 Year Rainfall Event Basin Area (Acres) C I Q cfs Offsite 1.44 0.668 7.50 7.21 Pond 3.81 0.668 7.50 19.09 Total 26.30 Restricted Post Runoff for a 50 Year Rainfall Event Basin Area (Acres) C I Q cfs) Offsite 1.44 0.668 7.50 7.21 Structure 1" Orifice=0.015 Primary Weir=0.39 Secondary Weir=1.50 1.91 Total 9.12 Primary weir calculator Given Input Data: weir Type ....................... Rectangular Equation ....................... Suppressed solving for ..................... Flowrate Depth of Flow ................... 2.6500 in coefficient ..................... 0.6000 Height .......................... 2.6500 in computed Results: Flowrate ........................ 0.3885 cfs Full Flow ....................... 0.3885 cfs velocity ........................ 1.5079 fps width ........................... 14.0000 in Area ............................ 0.2576 ft2 Perimeter ....................... 19.3000 in wet Perimeter ................... 19.3000 in wet Area .................... 0.2576 ft2 Percent Full .................... 100.0000 secondary weir calculator Given Input Data: weir Type ....................... Rectangular Equation ....................... Suppressed solving for ..................... Flowrate Depth of Flow ................... 2.6500 in coefficient ..................... 0.6000 Height .......................... 2.6500 in computed Results: Flowrate ........................ 1.4984 cfs Full Flow ....................... 1.4984 cfs velocity ........................ 1.5079 fps width 54.0000 in Area ............................ 0.9937 ft2 Perimeter ....................... 59.3000 in Wet Perimeter ................... 59.3000 in Wet Area .................... 0.9937 ft2 Percent Full .................... 100.0000 % Design Calculations Stormwater Treatment Facilities for Canebreak Apartments located in Wilmington, N.0 1. PROJECT DESCRIPTION The Project consist of a proposed 32 unit apartment complex located on a 5.25 Ac. tract in Wilmington, N.C. 2. COMPUTE POND AREA REQUIRED a. Compute Percent Impervious: Impervious Areas: On -Site Buildings On -Site Streets and Parking N/A On -Site Sidewalks Other on -site Off -site Sub -Total 0 93,046 FUTURE Total 0 93,046 Total Area Drainage to Pond: Percent Impervious = 0.561 or 56.1 % Total 33,831 SF 44,015 SF 0 SF 15,200 SF 0 0 93,046 SF 0 SF 93,046 SF _65x 66 SF b. Compute Pond Surface Area Using Surface Area to Drainage Area Ratio Chart for 85% TSS Removal (copy attached) and assuming g ,54 foot pond depth: SA/DA = = ; , ,. 99 % (interpolated) Therefore: Surface Area = SA/DA x Drainage Area 4,813 SF say ; r6800 SF c. Compute Minimum Pond Dimensions Assume rectangular shape with 3:1 Length (L) to Width (W) Ratio: Length = 142.83 feet Width = 47.61 feet Site conditions, however, dictate: Length = "I-F 7,-1,910 feet so, Width (avi 60.0 feet Actual LIW = 3.2 3. DETERMINE VOLUME TO BE CONTROLLED FROM 1" STORM Using Schuler "Simple Method": Rv = 0.05 + 0.009(I) where I = percent impervious Rv = 0.555 in/in Control Volume = Design Rainfall x Rv x Drainage Area Control Volume = 7,670 CF say:: `8000 CF 4. DETERMINE REQUIRED STORAGE DEPTH Assume: 3:1 side slopes solving for depth (d) by trial & error: d = 1.13 5. DETERMINE ORIFICE SIZE Control Volume must be drawn down over a 2 day - 5 day period. Using orifice equation, solve for Diameter (D) that results in 3-1/2 day period: D = (Q / 0.026 (h).$) 5 Where: Q = (Control Volume / 3.5 days x 86,400 sec/day) = 0.026 cfs h=d/2 = 0.57 Solving for D: D = 1.16 Use C,,,11771 00 "pipe Actual Drawdown with actual drawdown pipe diameter (using orifice equation): Q= 0.020 cfs Draw Down Period = 4.74 days OK, < 5.0 6. SELECT OUTLET STRUCTURE DIAMETER Size outlet structure such that depth of 010 flow <1.0 feet: Using Rational Formula (Q=CIA) where: Cimper Cpery = =�:0'2 Ccum = 0.7 110 = ` U5-0� inlhr A = 3.81 ac Q 10 = 16.54 cfs Assuming 1/2 circumference is used as weir and using Francis Formula (0=3.331-1-11'5) to solve for L such that H = 1.0: L = 4.97 Feet Use 36 inch diameter outlet structure 7. DETERMINE Q10 STAGE Q 10 = 16.54 cfs Using Francis Formula (Q=3.33LH' 5) solve for H: H10 = 1.04 feet 8. DETERMINE Q100 STAGE (ELEV. OF EMERGENCY SPILLWAY) Using Rational Formula (Q=CIA) where: Ccum = 0.67 1100 = ,54- &, 7 inlhr A = 3.81 ac Q100 = 21.63 Using Francis Formula (Q=3.33LH'*5) solve for H: H100 = 1.24 feet 9. DETERMINE 0100 STAGE OVER EMERGENCY SPILLWAY (TOP BERM ELEV.) Assume primary spillway blocked (i.e., emergency spillway to accommodate Q100) Emergency spillway shall be a broad crested earthern weir designed to pass 100 year storm. Using broad crested weir equation H = (QICw x L)2r3 where: Q = Q100 21.63 cfs Cw = 3.0 Length = °-Km `:f+50 feet H = 0.28 feet 10. FORESAY SIZING Compute Actual Pond Volumes (using average end method): Main Bay Volume: Pond Bottom Bottom Veg Shelf Normal Pond Main Bay Volume = Forebay Volume: Pond Bottom Normal Pond Forebay Volume = Total Pond Volume = Avg Incr. Incr. Cum. Elevation Area SF Area SF Depth (FT) Vol CF Vol CF =m30 00 F. ' 2 4381 n, 34"00 __" 4'7.42 3,590 4.00 14,360 14,360 ry35.40,.jf 7,823 6,283 1.40 8,795 23,156 23,156 CF Elevation Area SF Area SF Depth (FT) Vol CF Vol CF 30.00 35 40 ,� 3;244i 1,936 5.40 10,454 10,454 10,454 CF 33,610 CF Forebay Volume equates to 31.1 % of Total Volume Temp. Storage Volume: Elevation Area SF Area SF Depth (FT) Vol (CF) Vol CF Normal Pond 35.40 11,067 Temp. Pond Level 36.53 12;62_ 11,847 1.13 13,387 13,387 Temp. Pool Volume = 13,387 CF 11. SUMMARY Pond Elevations: Top Berm (minimum) H= 0.26 100-Yr. Flood H100 = 1.24 10-Yr. Flood H10 = 1.04 1-inch Storage storage depth = 1.13 Permanent Pool pond depth = 5.4 Pond Bottom 12. WET DETENTION BASIN SUPPLEMENT Basin Bottom Elevation 30.00 Perm. Pool Elevation 35A0 Temp. Pool Elevation 36.53 Perm Pool Surface Area 11,067 SF Drainage Area 3.81 AC Impervious Area 2.14 AC Perm. Pool Volume 33,610 CF Temp Pool Volume 13,387 CF Forebay Volume 10,454 CF SA/DA 2.9 Diameter of Orifice 1.00 Design Rainfall ill Design TSS Removal 90% Relative Actual 8.04 38.04 26 7.77 37.77 (emerg. weir elev) 7.57 37.57 6.53 36.53 (primary weir elev) 5.40 35.40 (invert out elev) 0 �0:00 FILE MODE 769� MEMORY TX * * * COMMUNICATION RESULT REPORT ( JUL.30.2004 OPTION REASON FOR ERROR E-1) HANG UP OR LINE FAIL E-3) NO ANSWER ADDRESS(GROUP) - e-3342725464 P. 1 8:11AN ) TTI NCDENR WIRO RESULT PAGE --------------------P--lf1 OK E-2) BUSY E-4) NO FACSIMILE CONNECTION A OAUEN NCDENR North Carolina Department of Environment and Natural Resources Division of Water Quality Michael F. Easley, Governor FAX COVER SHEET Date: July 29, 2004 To: H. Kenneth White, P.E. Company: H. Kenneth White & Asoc, FAX #: 334-272-54M 54(o4 William G. Ross, Jr., Secretary Alan W. Klimak, P.E., Director No. of Pages: 1 From: Linda Lewis Water Quality Section - Stormwater FAX # 910-350-2004 Phone # 910-395-3900 DWQ Stormwater Project Number: SW8 040124 Project Name: Canebreak Apartments MESSAGE: Mr. White: - The Division received previously requested information regarding the subject application on May 11, 2004. The application is still incomplete. Please provide the following items prior to August 29, 2004„to continue the review; I� 1. Please add a dimensioned building detail for the smnllAr hiiiirlinn tha nm,ohn ��a 4k., �, Al NCDENR North Carolina Department of Environment and Natural Resources Division of Water Quality Michael F. Easley, Govemor William G. Ross, Jr., Secretary Alan W. Klimek, P.E., Director FAX COVER SHEET Date: July 29, 2004 No. of Pages: 1 To: H. Kenneth White, P.E. From: Linda Lewis Company: H. Kenneth White & Asoc.. Water Quality Section - Stormwater FAX #: 334-272- " 54(A- FAX # 910-350-2004 Phone # 910-395-3900 DWQ Stormwater Project Number: SW$ 040124 Project Name: Canebreak Apartments MESSAGE: Mr. White: The Division received previously requested information regarding the subject application on May 11, 2004. The application is still incomplete. Please provide the following items prior to August 29, 2004,,to continue the review: ff 1. Please add a dimensioned building detail for the smaller building, the gazebo, and the shuffleboard area. 2. The orifice calculation is not correct. It appears that you are using the average head based on the 1" storage depth of 0.67'. This is not correct. The temporary pool depth you have specified on the plans is 1.13' above the permanent pool, therefore, the average head is in the neighborhood of .56', not .34'. However, please continue to use a control volume that equates to the 1" volume. If you provide an outlet weir at elevation 36.07, then you can use an average head of .34' to size the orifice, but since the "primary weir" in the riser is set at 36.53, you need to use a .56' head. The 1" volume is the volume to be draw down in 2-5 days, in both situations. 3. 1 must have missed this item on the last review- please add the dimensions of the permanent pool contour, including straight lines, arcs, etc. RSSIarl: S:IWQSISTORMWATIADDINF0120041040124.ju104 ' Wilmington Regional Office 127 Cardinal Drive Extension, Wilmington, North Carolina 28405 Phone: 910-395-39001 FAX 910-350-20041 Internet: h2o.enr.state.nc.us An Equal Opportunity/Affirmative Action Employer — 50% Recycled110% Post Consumer Paper NorthCarohna ,Naturally