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HomeMy WebLinkAboutSW8060725_CURRENT PERMIT_20061013STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW DOC TYPE c- CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE ❑ COMPLIANCE EVALUATION INSPECTION DOC DATE 2� YYYYMMDD wAr�RpG N, 1' October 13, 2006 Mr. Clifford Schwenker, Member Manager Magnolia Trace Townhomes, LLC 416 Oceana Way Carolina Beach, NC 28428 Subject: Stormwater Permit No. SW8 060725 Magnolia Trace Townhomes High Density Project New Hanover County Dear Mr. Schwenker: Michael F. Easley, Govcmur William G. Ross Jr., Sccrctary North Carolina Department of Environment and Natoral Resources Alan W. Klimek, P.E. Director Division of Water Quality The Wilmington Regional Office received a complete Stormwater Management Permit Application for Magnolia Trace Townhomes on September 11, 2006. Staff review of the plans and specifications has determined that the project, as proposed, will comply with the Stormwater Regulations set forth in Title 15A NCAC 2H.1000. We are forwarding Permit No. SW8 060725 dated October 13, 2006, for the construction of the subject project. This permit shall be effective from the date of issuance until October 13, 2016, and shall be subject to the conditions and limitations as specified therein. Please pay special attention to the Operation and Maintenance requirements in this permit. Failure to establish an adequate system for operation and maintenance of the stormwater management system will result in future compliance problems. If any parts, requirements, or limitations contained in this permit are unacceptable, you have the right to request an adjudicatory hearing upon written request within sixty (60) days following receipt of this permit. This request must be in the form of a written petition, conforming to Chapter 150B of the North Carolina General Statutes, and filed with the Office of Administrative Hearings, P.O. Drawer 27447, Raleigh, NC 27611-7447. Unless such demands are made this permit shall be final and binding. If you have any questions, or need additional information concerning this matter, please contact Paul Bartlett, or me at (910) 796-7215. Sincerely, Edward Beck Regional Supervisor Surface Water Protection Section ENBlptb: S:1WQSISTORMWATERIPERMIT1060725.oct06 cc: Garry S. Pape, P.E., Withers & Ravenel, Inc. Tony Roberts, New Hanover County Building Inspections Beth E. Wetherill, New Hanover County Engineering Paul T. Bartlett, P.E. -Wilmington-Regional Office Central Files Onc No[ihCarolina Alatum!/Zy North Carolina Division of Water Quality 127 Cardinal Drive Extension Wilmington, NC 28405 Phone (910) 796-7215 Customer Service Wilmington Regional Office Internet: w'y�+v.ricvtat� tv.org Fax (910) 350-2004 1-877-623-6748 A Equal Opportunity/Affirmative Action Employer — 50% Recycled110% Post Consumer Paper State Stormwater Management Systems 'f' M Permit No. SW8 060725 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 Clifford Schwenker and Magnolia Trace Townhomes, LLC Magnolia Trace Townhomes 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 "storm water rules") and the approved stormwater management plans and specifications and other supporting data as attached and on fife 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 October 13, 2016, and shall be subject to the following specified conditions and limitations: 1. DESIGN STANDARDS 1. 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 126,188 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. The built -upon area for the future development is limited to 3,020 square feet (pool facility and future road extension) which is included in the total permitted impervious area of 126,188 square feet. 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. 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 060725 6. The following design criteria have been provided in the wet detention pond. -and must be maintained at design condition: a. Drainage Area, 9cres: 4.69 Onsite, ft : 204,470 Offsite, ft2: None b. Total Impervious Surface, ft2: Onsite Buildings, ft Onsite Parkinglpavement, ft?: Onsite Sidewalks, ft Other OS (pool/future road ext.), ft2: G. 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: 1. Receiving Stream/River Basin: M. Stream Index Number: n. Classification of Water Body: II. SCHEDULE OF COMPLIANCE .126,188 69,380 47,708 6,080 3,020 1.0 5.0 90% 19.0 9,181 11,161 20.1 1.5" O pipe 4,643 UT Mott Creek 1 Cape Fear 18-82 "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. 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. Page 3 -of 7 State Stormwater Management Systems Permit No. SW8 060725 5. Decorative spray fountains will be allowed ip 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 1/8 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 prior to 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. Further 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 4 of 7 Sta'e Stormwater Management Systems Permit No. SW8 060725 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 13th day of October 2006. NORTH ROLINA ENVIRONMENTAL MANAGEMENT COMMISSION for AI imek, :E., Director Division of Water Quality By Authority of the Environmental Management Commission Page 5 of 7 State Stormwater Management Systems Permit No. SW8 060725 Magnolia Trace Townhomes Stormwater Permit No. SW8 060725 Page 1 of 2 New Hanover County Designer's Certification I, , as a duly registered in the State of North Carolina, having been authorized to observe (periodically/ weekly/ full time) the construction of the project, (Project) for (Project Owner) hereby state that, to the best of my abilities, due care and diligence was used in the observation of the project construction such that the construction was observed to be built within substantial compliance and intent of the approved plans and specifications. The checklist of items on page 2 of this form is included in the Certification. Noted deviations from approved plans and specification: Signature Registration Number Date SEAL Page 6 of 7 State Stormwater Management Systems Permit No. SW8 060725 Page 2 of 2 Certification Requirements: 1. The drainage area to the system contains approximately the permitted acreage. 2. The drainage area to the system contains no more than the permitted amount of built -upon area. 3. All the built -upon area associated with the project is graded such that the runoff drains to the system. 4. All roof drains are located such that the runoff is directed into the system. 5. The outlet/bypass structure elevations are per the approved plan. 6. The outlet structure is located per the approved plans. 7. Trash rack is provided on the outlet/bypass structure. 8. All slopes are grassed with permanent vegetation. 9. Vegetated slopes are no steeper than 3:1. 10. The inlets are located per the approved plans and do not cause short- circuiting of the system. 11. The permitted amounts of surface area and/or volume have been provided. 12. Required drawdown devices are correctly sized per the approved plans. 13. All required design depths are provided. 14. All required parts of the system are provided, such as a vegetated shelf, and a forebay. 15. The required system dimensions are provided per the approved plans. cc: NCDENR-DWQ Regional Office Tony Roberts, New Hanover County Building Inspections Page 7 of 7 -7124- A,11�A NCDENR North Carolina Department of Environment and Natural Resources 127 Cardinal Drive, Wilmington NC 28405 (910) 796-7307 FAX (910) 350-2004 Request for Express Permit Review FILL-IN all information below and CHECK required Permit(s). FAX or email to Cameron. Weavet@ncmail.net along with a narrative and vicinity map of the project location. Projects must be submitted by 9:00 A.M. of the review date, unless prior arrangements are made. APPLICANT Name Marcus Schwenker Company Soss & Schwenker, LLC Address 4102 Emerson Street City/State Wilmington, NC Zip 28403 County New Hanover -Phone Fax Email PROJECT Name Maanolia Trace Townhomes PROJECT SYSTEM(S) TRIBUTARY TO MOTT CREEK (STREAM NAME) Cape Fear RIVER BASIN ENGINEER/CONSULTANT Company Withers & Ravenel Inc. — Garry S. Pape, P.E Address 7040 Wrightsville Avenue — City/State _ Wilmington, NC Zip 28403 County New Hanover Phone 910-256-9277 Fax 910-256-2584 Email gpape(cDwithersravenel.com --------------------------------------------------------------------------------------------------------------------------------------------------------------------- State or National Environmental Policy Act (SEPA, NEPA) — EA or EIS Required ❑ Yes ❑ No ❑ STREAM ORIGIN Determination; # of stream calls; Stream Name ❑ STORM_ WATER ❑ Low Density ® High Density -Detention Pond ❑ High Density -Other Wetlands MUST be addressed below ❑ Low Density -Curb & Gutter ❑ High Density -Infiltration ❑ Off Site ❑ COASTAL ❑ Excavation & Fill ❑ Bridges & Culverts ❑ Structures Information MANAGEMENT ❑ Upland Development ❑ Marina Development ❑ Urban Waterfront ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- ❑ LAND QUALITY ❑ Erosion and Sedimentation Control Plan with acres to be disturbed. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- WETLANDS (401) Wetlands on Property ® Yes ❑ No Isolated Wetlands on Property. ® yes ❑ No Check all that app1V Wetlands Will Be Impacted ® Yes ❑ No Wetland Impacts.- 0.05 Acre(s) Wetlands Delineation has been completed ® Yes ❑ No ❑ Buffers Impacted: Acre(s) USA COE Approval of Delineation completed ® Yes ❑ No 404 Application in process wIUSACOE ❑Yes ❑No I Permit received from USACE ❑Yes []No 401 Application required []Yes ❑ No If Yes, ❑ Regular ❑ Express ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Additional fees, not to exceed 50% of the original Express Review permit application fee, may be charged for subsequent reviews due to the insufficiency of the permit applications. For DENR use only SUBMITTAL DATES: Fee Split for multiple permits: SW $ CAMA $ Las $ 401 $ Total Fee Amount $ 5 i t P d �O �a �0 a�4 y�v VICINITY MAP (N. T. S.) NARRATIVE THIS 6.42 ACRE SITE IS LOCATED OFF CAROLINA BEACH ROAD IN THE CITY OF WILMINGTON. THE PROJECT PROPOSES DEVELOPMENT OF 50 TOWNHOUSE UNITS WITH WET DETENTION POND THAT OUTFALLS INTO MOTT CREEK (C, Sw). THE PRIMARY STORM WATER MEASURES WILL INCLUDE STORM GRATE INLETS AND OVERLAND SHEET FLOW THAT CONVEY THE STORM WATER TO A WET DETENTION POND. MAGNOLIA TRACE TOWN HOMES REQUEST FOR PRE -APPLICATION MEETING FOR EXPRESS PERMIT REVIEW MAY 31, 2006 I h ,� .O.IICEoUSE ONLY, _ _. Date Received Fee Paid Permit Number Mb 00 1 TOW OW7715-- State of North Carolina Department of Environmental and Natural Resources Division of Water Quality STORMWATER MANAGEMENT PERMIT APPLICATION FORM This form may he pholocopied for use as an original I. GENERAL INFORMATION l . Applicants name (specify the name of the corporation, individual, etc. who owns the project): Magnolia Trace Townhomes, LLC 2. Print Owner/Signing Official's name and title (person legally responsible for facility and compliance): Clifford Schwenker— Member Manager 3. Mailing Address for person listed in Item 2 above: 416 Oceana Way City: Carolina Beach _ _ State: T1 lephone Number: (910) 458-8966 Zip: 28428 4. Project Name (subdivision, facility, or establislunent name — should be consistent with project name on plans, specifications, letters, operation and maintenance agreements, etc.): Magnolia "f race Townhomes 5. Location of Project (street address): Carolina Beacli Road. Wiiminuton. North Carolina City: Wilmilwton County: New Hanover 6. Directions to project (from nearest major intersection): From Monkey Junction in Wilmin gt on, take Carolina Beach Road approx 2 miles towards downtown and site is on the right. 7. Latitude: 34' 09' 15" N Longitude: 770 54' 24" W of project. 8. Contact person who can answer questions about the project:: Name: Garry S. Pane_ PE Telephone Number: ( 910125E-9277 H. PERMIT INFORMATION: 1. Specify whether project is (clieck one): X New Renewal Modification Form SWU-101 Version 3.99 Page 1 of 2. If this application is being submitted as the result of a renewal or modification to an existing pert -nit, list the existing permit number and its issue date (if known) 3. Specify the type of'project (check one): Low Density X High Density Redevelop General Permit Other 4, Additional Project Requirements (check applicable blanks): CAMA Major Sedimentation/Erosion Control 404/401 Permit NPDFS Stormwater Information on required state permits can be obtained by contacting the Customer Service Center at 1-877-623-6748 III. PROJECT INFORMATION 1. In the space provided below, summarize how stormwater will be treated. Also attach a detailed narrative (one to two pages) describing stormwater management for the project. Stormwater will be treated by the use of wet detention pond 2. Stormwater runoff from this project drains to the Cape Fear River Basin. 3. Total Project Area: 6.42 acres. 4. Project Built Upon Area: 45.2 %. 5. Flow many drainage areas does the project have? 1 6. Complete the following information for each drainage area. If there are more than two drainage areas in the project, attach and additional sheet with the information for each area provided in the same format as below. Basin Information Drainage Area I Drainage Area 2 Receiving Stream Name Unnamed Trib to Molt Creek Receiving Stream Class C ; Sw Drainage Area 204,470 sf 4.69 ac Existing Im ervious*Area - 0 - Pro osed Impervious* Area 126,188 sf --- 2.90 ac % Impervious* Area `Total 61.7% Im ervious* Surface Area Drainage Area I Drainage Area 2 On -Site Rooftops 69,390 sf On -Site Streets - 0 - On -Site Parking/Pavement 47,708 sf On -Site Sidewalks 6,080 sf Other On -Site Pool Facility & Future Road Extension 3,020 sf Off -Site - 0 - Total: 126,188 sf --- 2.90 ac *Impervious area is defined as the built upon area including, hilt not limited to, buildings, roads, parking areas, sideivalks, gravel areas, etc. Form SWU-101 Version 3.99 Page 2 of 4 7. How was the off -site impervious area listed above derived`? IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS The following italicized deed restrictions and protective covenants are required to be recorded for all subdivisions, out parcels, and future devclopment prior to the sale of any lot. If lot sizes vary significantly, a table listing each lot number, size, and the allowable built -upon area for each lot must be provided as`an attachment. 1, The following covenants are intended to ensure ongoulg compliance with state stornlwaler management permil number as issued by the Division of Water Quality. These covenants play nol he changed or deleted without the consent of the Stale. 2. No more than square feet of any lot shall he covered by structures or impervious materials. Impervious nmlerials include asphalt, gravel, concrele, brick, stone, slate of similar material but not inchlde wood decking of the waler suiface of swimming pools. 3. .Swales shall not be filled in, piped, or alleged except as necessary to provkle driveway crossings. 4. Built -upon area in excess of the permilted amount requires a state slormwaler management permit modification prior to construction. S. All permitted runoff from the oulparcels or future. development shall be Lhrected into the permitted slorinwater conlrol system. These connections to the stormwater control system shall he petformed in a manner that mainlalns the integrity and peiformance of the system as permitleel. By your signature below, you certify that the recorded deed restrictions and protective covenants for this project shail include all the applicable items required above, that the covenants will be binding on all parties and persons claiming under than, that they will run with the land, that the required covenants cannot be changed or deleted without concurrence from the State, and that they will be recorded prior to the sale of any lot. V. SUPPLEMENT FORMS The applicable state storn»vater management permit supplement form(s) listed below must be submitted for each BM specified for this project. Contact the Stormwater and General Permits Unit at (919) 733-5083 for the status and availability of these forms. Form SWU-102 Wet Detention Basin Supplement Form SWU-103 Infiltration Basin Supplement Form SWU-104 Low Density Supplement Form SWU-105 Curb Outlet System Supplement Form SWU-106 Off -Site System Supplement Form SWU-107 Underground Infiltration Trench Supplement Form SWU-108 NCUse River Basin Supplement Forst SWU-109 Innovative Best Management Practice Supplement Form SWU-101 Version 3.99 Page 3 of VI. SUBMITTAL REQUIREMENTS Only complete application packages will be accepted and reviewed by the Division of Water Quality (DWQ). A complete package includes all of the items listed below. The complete application package should be submitted to the appropriate DWQ Regional Off ice. 1. Please indicate that you have provided the following required information by initialing in the space provided next to each item. • Original and one copy of the Stormwater Management Permit Application Form • One copy of the applicable Supplement Fonn(s) for each 13MP • Permit application processing fec of $420 (payable to NCDI?NR) • Detailed narrative description of stormwater treatment/management Two copies of plans and specifications, including: - Development/ Project name - Engineer and firm - Legend - North arrow - Scale - Revision number & date - Mean high water line - Dimensioned property/project boundary - Location map with named streets or NCSR numbers - Original contours, proposed contours, spot elevations, finished floor elevations - Details of roads, drainage features, collection systems, and stormwater control measures - Wetlands delineated, or a note on plans that none exist - Existing drainage (including off -site), drainage easements, pipe sizes, runoff calculations - Drainage areas delineated - Vegetated buffers (where required) VII. AGENT AUTHORIZATION If you wish to designate authority to another individual or firen so that they may provide information on your behalf, please complete this section. Designated agent (individual or firm): Withers & Ravenel, Inc. Mailing Address: _ 7040 Wrightsville Ave, Suite 101 City Wilmington State: NC Phone: ( 910) 256-9277 VIII. APPLICANT'S CERTIFICATION Zip: 28403 Fax: 910 256-2584 I, (print or t)pe name rf person listed in Genercil Information, Item 2) Clifford Schwenker certify that the information included on this permit application form is, to the best of my knowledge, correct and that the project will be constructed in conformance with the approved plans, that the required deed restrictions and protective covenants will be recorded, and that�lie proposed project complies with the requirements of 15A NCAC 21-I.1000. _ -4 /� Form SWU-101 Version 3.99 Page 4 of 6,11(106- leee ,SGJ0 060 72i Permit No. (to he provided by DWQ) State of North Carolina Department of Environment and Natural Resources Division of Water Quality STORMWATER MANAGEMENT PERMIT APPLICATION FORM WET DETENTION BASIN SUPPLEMENT "Phis f rrn 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. 1. PROJECT INFORMATION Project Name: M Contact Person: G lia Trace Town homes S. Pape, PE Phone Number: 910-256-9277 For projects with multiple basins, specify which basin this worksheet applies to: elevations Basin Bottom Elevation' Permanent Pool Elevation Temporary Pool Elevation 14.0 1t. 190 _ _ ft. 20.1 - ft. areas Permanent Pool Surface Area 9,181 Drainage Area 4_69 Impervious Area 2.90 volumes 14 10A -3/j06 Permanent Pool Volume 23,027 Temporary Pool Volume 11) Forebay Volume . 4,643 other parameters SA/DA' Diameter of Orifice Design Rainfall Design "I'SS Removal 2 Footnotes: (floor of the basin) (elevation of the orifice) (elev(16011 of the discharge structure ovei lon) sq. ft. (water surface area at llze orifice elevation) fie. (on -site and off -site clrrrilzcrge to the basin) ac. (on -site and off site drainage to the basin) cu. ft. (combined volume of main basin and forebay) cu. ft. (volume detained above the permanent pool) cu. ft. (approximately 20% of total volume) 4.42 1.5 I.0 90 % (.vurface area to drainage area ratio fr•oln, DWQ table) (2 to 5 day temporary pool draw -down required) (minimum 85% required) ' When using the Division SAIDA 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 nonstandard 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 BMP manual provides design tables for both 85% TSS removal and 90% TSS removal. Form S W U-102 Rev 3.99 Page I of 4 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 Stormwater Management Permit Application Form, the agent may initial below. If a requirement has not been met, attach justification. App icants Initials a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet). Sl b. The forebay volume is approximately equal to 20% of the basin volume. c. The temporary pool controls runoff from the design storm event. S` d. The temporary pool draws down in 2 to 5 days. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow calculations) �S10 f. The basin length to width *ratio is greater than 3: 1. g. The basin side slopes above the permanent pool are no steeper than 3: 1. S h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail). S 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. 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. in. 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) 0 does 6does not incorporate a vegetated filter at the outlet. This system (check one) 0 does does not incorporate pretreatment other than a forebay. Form S WU-102 Rev 3.99 Page 2 of 4 Maintenance activities shall be performed as follows: 1. 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. 2. 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 (i.e. catch basins, piping, swales, riprap, etc.) quarterly to maintain proper functioning. 4. Remove accumulated sediment from 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 When the permanent pool depth reads Sediment Re oval El. 75 Bottom Ele ation 4ti 0 FOREBAY t"LT feet in the main pond, the sediment shall be removed. l•ZS" feet in the forebay, the sediment shall be removed. BASIN DIAGRAM (fill in the blanks) Permanent Pool Elevation tq�b Sediment Removal Elevation 15.2,57 75% Bottom Elevation 14„0 125% uIAVil f717,11-11 5. 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. 6. 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. 7. All components of the wet detention basin system shall be maintained in good working order. Form SWU-102 Rev 3.99 I'age 3 of4 I acknowledge and agree by my signature below that I am responsible for the performance of the seven maintenance procedures listed above. 1 agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Print name: Clifford Schwenker Title: Member Manager Address: 416 Occana Way, Carolina Beach, North Carolina 28428 Phone: 910- 45878966 Date: Signal 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, 1 L. LgD��e- a Notary Public for the State of County of NOD �rloy2(- do hereby certify that C�Ly���nI�J�C1C' personally appeared before me this day of due LS-�- 20C o and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, SEAL My commission expires Y Form S W U-102 Rev 3.99 Page 4 of 4 State Stormwater Management Systems Permit No. SW8 060725 Magnolia Trace Townhomes Stormwater Permit No. SW8 060725 New Hanover Count Designer's Certification Page 1 of 2 1, Gkfr\AS-e3�� as a duly registered PVN,JVtW in the State of Ndkth Carolina, -having been authorized to observe (periodically/ wee 1y1 full time) the construction of the project, r (Proje —Z w n�cp-Q--> for � (Project Owner) hereby state that, to the best of my abilities, due care and diligence was used in the observation of the project construction such that the construction was observed to be built within substantial compliance and intent of the approved plans and specifications. The checklist of items on page 2 of this form is included in the Certification. Noted deviations from approved plans and specification: Signature .—b Registration Number O 3t3>> Date a '1Z212AIS, Page 6 of 7 State Stormwater Management Systems Permit No. SW8 060725 Page 2 of 2 Certification'Requirements: 1. The drainage area to the system contains approximately the permitted 2. acreage. The drainage area to the system contains no more than the permitted amount of built -upon area. All built -upon �8. the area associated with the project is graded such that the runoff drains to the system. All roof drains are located such that the runoff is directed into the system. �5. The outlet/bypass structure elevations are per the approved plan. s The outlet structure -is located per the approved plans, i�__V7- Trash rack is provided on the outlet/bypass structure. 8. All slopes are grassed with permanent vegetation. _9. Vegetated slopes are no steeper than 3:1. 10. The inlets are located per the approved plans and do not cause short- circuiting of the system. 11. The permitted amounts of surface area and/or volume have been provided. 2. Required drawdown devices are correctly sized per the approved plans. 13, All required design depths are provided. _14: All required parts of the system are provided, such as a vegetated shelf, and a forebay. 15. The required system dimensions are provided per the approved plans. cc: NCDENR-DWQ Regional Office Tony Roberts, New Hanover County Building Inspections Page 7 of 7