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HomeMy WebLinkAboutSW8080317_CURRENT PERMIT_20120329STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW8 010'3 1 DOC TYPE CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE ❑ COMPLIANCE EVALUATION INSPECTION DOC DATE `L012U320% YYYYMMDD F� NC®ENR North Carolina Department of Environment and Natural Resources Division of Water Quality Beverly Eaves Perdue Charles Wakild, P. E. Dee Freeman Governor Director Secretary March 29, 2012 Mr. Randy Blanton PO Box 10137 Wilmington, NC 28404 Subject: Approved Plan Revision and Permit Extension Covil Gardens Stormwater Permit No. SW8 080317 New Hanover County Dear Mr. Blanton: On March 22, 2012, the Wilmington Regional Office received a request to revise the approved plans for Stormwater Management Permit Number SW8 080317. The revisions include reallocating impervious area as described in the table below. It has been determined that a formal permit modification is not required for the proposed changes. We are forwarding you an approved copy of the revised plans for your files. Please replace the old approved plan sheets with the new ones. Onsite Buildings Onsite Parking/Asphalt Onsite Sidewalks/Concrete Future Total 5/24/11 Permit 3/29/11 Plan Revision Pond (DA 1) Sand Filter (DA2) Pond (DA 1) Sand Filter (DA2) 12,880 1,715 13,141 1,91S 22,281 6,419 21,985 5,906 8,973 600 8,735 637 6,626 1 0 1 6,898 1 276 50,760 1 8,734 1 50,759 1 8,734 Please be aware that all terms and conditions of the permit issued on May 24, 2011, remain in full force and effect. Please also understand that the approval of this revision to the approved plans for the subject State Stormwater Permit is done on a case -by -case basis. On August 5, 2009, the Governor signed Session Law 2009-406. This law impacts any development approval issued by the Division of Water Quality under Article 21 of Chapter 143 of the General Statutes, which is current and valid at any point between January 1, 2008, and December 31, 2010. The law extends the effective period of any stormwater permit that was set to expire during this time frame to three (3) years from its current expiration date. On August 2, 2010, the Governor signed Session Law 2010-177, which granted an extra year for a total of four (4) years extension. The Division is hereby notifying you that permit SW8 080317 has been issued a Plan Revision and shall be effective until January 31, 2019, which includes the permit extension. Please attach this letter to your High Density Permit most recently issued on May 24, 2011. Any other changes to this project must be approved through this Office prior to construction. The issuance of this plan revision does not preclude the pennittee from complying with all other applicable statutes, rules, regulations or ordinances which may have jurisdiction over the proposed activity, and obtaining a permit or approval prior to construction. Wilmington Regional Office 127 Cardinal Dnve Extension, Wilmington, North Carolina 28405 One Phone 910-796-72151 FAX. 910-350-20041 DENR Assistance: 1-877-623-6748 NorthCarolina Internet. w .nmaterquality.org ��/� atima//ff An Equal Opportunity l AKrmAction ative Employer K` L " If you have any questions concerning this matter, please do not hesitate to call Georgette Scott or me at (910) 796-7215. Sincer I II Joi son Envir mental Engineer GDS*pj: SAWQS1StormwateAPermits & Projects120081080317 HD12012 03 permit_pr 080317 cc: Phil Tripp, PE Inspector, New Hanover County Building Inspections Wilmington Regional Office Page 2 of 2 1nWWthl 1 A1k-t7ft7 e n1 (oldo8• ?o'".1ut) K Ft If+ fO\Q 6hgl�C. cuV,.riJeq `�i 0_ to 0.0 (y�- Wet Detention Basin Inspection and Maintenance Agreement �A)3O9ZS/% I will keep a maintenance record on this BMP. This maintenance record will be kept in a log in a known set location. Any deficient BMP elements noted in the inspection will be corrected, repaired or replaced immediately. These deficiencies can affect the integrity of structures, safety of the public, and the removal efficiency of the BMP. 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): ❑ does ® does not incorporate a vegetated filter at the outlet. This system (check one): ❑ does ® does not incorporate pretreatment other than a IForebay. Important maintenance procedures: - Immediately after the wet detention basin is established, the plants on the vegetated shelf and perimeter of the basin should be watered twice weekly if needed, until the plants become established (commonly six weeks). - No portion of the wet detention pond should be fertilized after the first initial fertilization that is required to establish the plants on the vegetated shelf. - Stable groundcover should be maintained in the drainage area to reduce the sediment load to the wet detention basin. - If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through the emergency drain should be minimized to the maximum extent practical. - Once a year, a dam safety expert should inspect the embankment. After the wet detention pond is established, it should be inspected once a month and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of inspection and maintenance should be kept in a known set location and must be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. BMP element: Potentialproblem: How I will remediate theproblem: The entire BMP Trash/debris is present, Remove the trash/debris. The perimeter of the wet detention basin Areas of bare soil and/or erosive gullies have formed. Regrade the soil if necessary to remove the gully, and then plant a ground cover and water until it is established. Provide time and a one-time fertilizer application. Vegetation is too short or too Ion Maintain vegetation at a height of aDDroximatpiv six inches. BMP element: Potentialproblem: How I will remediate theproblem: The inlet device: pipe or Swale The pipe is clogged. Unclog the pipe. Dispose of the sediment off -site. The pipe is cracked or Replace the pipe. otherwise dama ed. Erosion is occurring in the Regrade the Swale if necessary to Swale. smooth it over and provide erosion control devices such as reinforced turf matting or riprap to avoid future problems with erosion. The forebay Sediment has accumulated to Search for the source of the a depth greater than the sediment and remedy the problem if original design depth for possible. Remove the sediment and sediment storage dispose of it in a location where it will not cause impacts to streams or the BMP. Erosion has occurred. Provide additional erosion protection such as reinforced turf matting or riprap if needed to reventfuture erosion problems. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. The vegetated shelf Best professional practices show that pruning is needed Prune according to best professional practices to maintain optimal plant health. Plants are dead, diseased or Determine the source of the dying. problem: soils, hydrology, disease, etc. Remedy the problem and replace plants. Provide a one-time fertilizer application to establish the ground cover if a soil test indicates it is necessary, Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. The main treatment area Sediment has accumulated to Search for the source of the a depth greater than the sediment and remedy the problem if original design sediment possible. Remove the sediment and storage depth. dispose of it in a location where it will not cause impacts to streams or the BMP. Algal growth covers over Consult a professional to remove 50% of the area. and control the algal Eowth. Cattails, phragmites or other Remove the plants by wiping them invasive plants cover 50% of the basin surface. with pesticide (do not spray) BMP element: Potentialproblem: How I will remediate theproblem: The embankment Shrubs have started to grow Remove shrubs immediately. on the embankment. Evidence of muskrat or Use traps to remove muskrats and beaver activity is present. consult a professional to remove beavers. A tree has started to grow on Consult a dam safety spenalist to the embankment. remove the tree. An annual inspection by an Make all needed repairs. appropriate professional shows that the embankment needs repair. The outlet device Clogging has occurred. Clean out the outlet device. Dispose of the sediment offsite. The outlet device is damaged Repair or replace the outlet device. The receiving water Erosion or other signs of Contact the local NC Division of damage have occurred at the Water Quality P.egional Office, or outlet. the 401 Oversight Unit at 919-733- 1786. 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 _9_0_ feet in the main pond, the sediment shall be removed. When the permanent pool depth reads 4.0 feet in the forebay, the sediment shall be removed. Sediment Removal Bottom BASIN DIAGRAM 601 in the blanks) Permanent Pool Elevation 29.0 2-i 0 Pe marten Pool --------------- Volume Sediment Removal Elevation �trrr-' 2�-� Volume 290 -ft Min. -------------------------------------------- ------ Sediment Bottom Elevation49-R-?A O 1-R n. Storage Sediment pot-ageFOREBAY MAIN POND 6VVW yL9-1 RECEIVED LMAY 02 2011 ___ I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Print name:Randv Blanton Address:P.O. Box 10137, Wilmington NC 28404 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, —DPRO C3/ cj a Notary Public for the State of CAtah'i County of _, do hereby certify that n v personally appeared before me this 3D day of o Jrmbfr , ZOO , and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, SEAL My commission expires f Cti -17 -11 Wet Detention Basin Inspection and Maintenance Agreement I will keep a maintenance record on this BMP. This maintenance record will be kept in a log in a known set location. Any deficient BMP elements noted in the inspection will be corrected, repaired or replaced immediately. These deficiencies can affect the integrity of structures, safety of the public, and the removal efficiency of the BMP. 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): ❑ does does not incorporate a vegetated filter at the outlet. This system (check one): ❑ does [55�11 does not incorporate pretreatment other than a forebay. Important maintenance procedures: — Immediately after the wet detention basin is established, the plants on the vegetated shelf and perimeter of the basin should be watered twice weekly if needed, until the plants become established (commonly six weeks). — No portion of the wet detention pond should be fertilized after the first initial fertilization that is required to establish the plants on the vegetated shelf. — Stable groundcover should be maintained in the drainage area to reduce the sediment load to the wet detention basin. — If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through the emergency drain should be minimized to the maximum extent practical. — Once a year, a dam safety expert should inspect the embankment. After the wet detention pond is established, it should be inspected once a month and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of inspection and maintenance should be kept in a known set location and must be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. BMP element: Potentialproblem: How I will remediate theproblem: The entire BMP Trash/debris is present. Remove the trash/debris. The perimeter of the wet detention basin Areas of bare soil and/or erosive gullies have formed. Regrade the soil if necessary to remove the gully, and then plant a ground cover and water until it is established. Provide lime and a one-time fertilizer application. Vegetation is too short or too Maintain vegetation at a height of long. approximately six inches. BMP element: Potentialproblem: How I will remediate theproblem: The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the swale sediment off -site. The pipe is cracked or Replace the pipe. otherwise damaged. Erosion is occurring in the Regrade the swale if necessary to Swale. smooth it over and provide erosion control devices such as reinforced turf matting or riprap to avoid future problems with erosion. The forebay Sediment has accumulated to Search for the source of the a depth greater than the sediment and remedy the problem if original design depth for possible. Remove the sediment and sediment storage. dispose of it in a location where it will not cause impacts to streams or the BMP. Erosion has occurred. Provide additional erosion protection such as reinforced turf matting or riprap if needed to prevent future erosion problems. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than s ra in . The vegetated shelf Best professional practices Prune according to best professional show that pruning is needed practices to maintain optimal plant health. Plants are dead, diseased or Determine the source of the dying. problem: soils, hydrology, disease, etc. Remedy the problem and replace plants. Provide a one-time fertilizer application to establish the ground cover if a soil test indicates it is necessary. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. The main treatment area Sediment has accumulated to Search for the source of the a depth greater than the sediment and remedy the problem if original design sediment possible. Remove the sediment and storage depth. dispose of it in a location where it will not cause impacts to streams or the BMP. Algal growth covers over Consult a professional to remove 50% of the area. and control the algal growth - Cattails, phragmites or other Remove the plants by wiping them invasive plants cover 50% of with pesticide (do not spray). the basin surface. BMP element: Potentialproblem: How I will remediate theproblem: The embankment Shrubs have started to grow Remove shrubs immediately. on the embankment. Evidence of muskrat or Use traps to remove muskrats and beaver activity is present. consult a professional to remove beavers. A tree has started to prow on Consult a dam safety specialist to the embankment. remove the tree. An annual inspection by an Make all needed repairs. appropriate professional shows that the embankment needs re air. The outlet device Clogging has occurred. Clean out the outlet device. Dispose of the sediment off -site. The outlet device is damaged Repair or replace the outlet device. The receiving water Erosion or other signs of Contact the, local NC Division of damage have occurred at the Water Quality Regional Office, or outlet. the 401 Oversight Unit at 919-733- 1786. The measuring device used to determine the sediment elevation shall he such that it will give an accurate depth reading and not readily penetrate into accumulated sediments. When the permanent pool depth reads _90 feet in the main pond, the sediment shall be removed. When the permanent pool depth reads _4.0 feet in the forebay, the sediment shall be removed. Sediment Removal Bottom 25.0 --------------- BASIN DIAGRAM ill in the blanks) t--ft Min. Sediment Storage Permanent Pool Elevation 29.0 Pool Sediment Removal Elevation 20.0 Volume \--'---------- ------- -------- ---- ---'-------' ----- Bottom Elevation FOREBAY MAIN POND 1-ft Storage I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Print name:Randy Blanton Address:P.O. Box 10137, Wilmington, NC 28404 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. 1, :I)e.tl a C In i rd , a Notary Public for the State of Cac6jjnG_ , County of P(,pf{.pr , do hereby certify that personally appeared before me thisc30 day of %V f�_, ZjO , and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, ` C. o`Ot� ..: �,.. • NOTAgy=:� "qnyou% SEAL /�Ijk G .dam My commission expires f (1-15-11 Permit Number: O (to be provided by DWQ) Drainage Area Number: Sand Filter Operation and Maintenance Agreement I will keep a maintenance record on this BMP. This maintenance record will be kept in a log in a known set location. Any deficient BMP elements noted in the inspection will be corrected, repaired or replaced immediately. These deficiencies can affect the integrity of structures, safety of the public, and the removal efficiency of the BMP. Important maintenance procedures: — The drainage area will be carefully managed to reduce the sediment load to the sand filter. — The sedimentation chamber or forebay will be cleaned out whenever sediment depth exceeds six inches. — Once a year, sand media will be skimmed. — The sand filter media will be replaced whenever it fails to function properly after maintenance. The sand filter will be inspected quarterly and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of operation and maintenance will be kept in a known set location and will be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. 'BMP element:^ •:` - "' _Pdtential,problem: How I will remediate tfie'problem:: &,<a' Entire BMP Trash/debris is present. Remove the trash/debris. Adjacent pavement (if Sediment is present on the Sweep or vacuum the sediment as soon as applicable) pavement surface. possible. Perimeter of sand filter Areas of bare soil and/or erosive Regrade the soil if necessary to remove the gullies have formed. gully, and then plant a ground cover and water until it is established. Provide lime and a one-time fertilizer application. Vegetation is too short or too long. Maintain vegetation at an appropriate height. Flow diversion structure The structure is clogged. Unclog the conveyance and dispose of any sediment offsite. The structure is damaged. Make any necessary repairs or replace if damage is too large for repair. Forebay or pretreatment area Sediment has accumulated to a Search for the source of the sediment and depth of greater than six inches. remedy the problem if possible. Remove the sediment and stabilize or dispose of it in a location where it will not cause impacts to streams or the BMP. Erosion has occurred. Provide additional erosion protection such as reinforced turf matting or riprap if needed to prevent future erosion problems. Weeds are present. Remove the weeds, preferably by hand. If a pesticide is used, wipe it on the plants rather than s ra in . RECEIVED APR 0 5 2011 Form SW401-Sand Filter O&M-Rev.4 2009Septl7 Page 1 of 3 ;How I,will,remediate?ttie roble''m:= Filter bed and underdrain Water is ponding on the surface for Check to see if the collector system is collection system more than 24 hours after a storm. clogged and flush if necessary. If water still ponds, remove the top few inches of filter bed media and replace. If water still ponds, then consult an expert. Outlet device Clogging has occurred. Clean out the outlet device. Dispose of the sediment offsite. The outlet device is damaged Repair or replace the outlet device. Receiving water Erosion or other signs of damage Contact the NC Division of Water Quality have occurred at the outlet. 401 Oversight Unit at 919-733-1786. �, r APR 0 5 2011 Form SW401-Sand Filter O&M-Rev.4 2009Septl7 Page 2 of 3 Permit Number: (to be provided by DWQ) I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Project name:Covil Gardens BMP drainage area number:2 Print name:Randy Blanton Address:P.O. Box 10137, Wilmington, NC 28404 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, _ o& C . %?a Oak a Notary Public for the State of Cr,✓ol , County of f,( do hereby certify that aA6%t L a personally appeared before me this 3 day of MWrl-. 21DI I , and acknowledge the due execution of the forgoing sand filter maintenance requirements. Witness my hand and official seal, �:'NOTAgy,� e . s �,A pUBL1G.:a`c COUTA ` tttmninnu�a SEAL My commission expires APR 0 5 J0\% Form SW401-Sand Filter O&M-Rev.4 2009Sept17 Page 3 of 3 t •. . - , 1.� DWQ USE -ONLY -_ Date Received Fee Paid (express only) Permit Number State of North Carolina Department of Environment and Natural Resources Division of Water Quality STORMWATER MANAGEMENT PERMIT PLAN REVISION APPLICATION FORM This form may be photocopied for use as an original I. GENERAL INFORMATION 1. Stormwater Management Permit Number: SW8 080317 2. Project Name: 3. Permit Holder's name (specify the name of the corporation, individual, etc.): 4. Print Owner/Signing Official's name and title (person legally responsible for permit): Randy Blanton 5. Mailing Address for person listed in item 2 above: City:Wilmington State:NC Zip:28404 Phone: (910 1 540-7285 Fax: Email: GEI V® !I. PLAN REVISION INFORMATION 1. Summarize the plan revision proposed (attach additional pages if needed): The proposed changes include revised building footprints decreased parking area and revised sidewalks The overall impervious to each BMP remained the same III. 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 DWQ Office that issued the permit. 1. Please indicate that you have provided the following required information by initialing in the space provided next to each item. Initials • Original £a 1 copy of the Plan Revision Application Form /z-e • Two (2) copies of revised plans (must be revisions of original approved plan sheet(s))yL If applying for Express review (only available in 20 coastal counties): • Application fee of $500.00 (made payable to NCDENR) �ZA VI. APPLICANT'S CERTIFICATION I, (print or hype naive of person listed in General Information, item 3) Randy Blanton certify that I have aullorized these plan revisions and that the information included on this plan revision application is, to st of my know d corr and complete. 7 Signature: ri-.'/aJ�, Date: J � 2 1 �/;Z Plan Revision Form Rev 13July2010 Page I of I Permit No`_�5'� (to be provided by OWQ) AW ATEgOG NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM o g 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part IIQ must be printed, filled out and submitted along with all of the required information. I: PROJECT INFORMATION Project name Covil Gardens - Contact person Phil Trim. P E. Phone number Date Drainage area number 910-763-5100 II. DESIGN INFORMATION, Site Characteristics Drainage area 74,076 'ry2 Impervious area 50,760 rye % impervious 68.52421837 % Design rainfall depth 1.5 ; in Storage Volume: Non -SR Waters Minimum volume required 6,173 rya Volume provided 9,085 rya Storage Volume: SR Waters 1-yr, 24-hr runoff depth in Pre -development 1-yr, 24-hr runoff - ff3 Post -development 1-yr, 24-hr runoff ft3 Minimum volume required ff3 Volume provided •ff3 Peak Flow Calculations Is pre/post control of the 1-yr 24-hr peak flow required? y .(Y or N) 1-yr. 24-hr rainfall depth 3.9 'in Rational C, pre -development _ 0.3 r(unitless) Rational C, post -development 0.7 (unitless) Rainfall intensity: 1-yr, 24-hr storm 5.6 in/hr Pre -development 1-yr, 24-hr peak flow 27 ff3lsec Post -development 1-yr, 24-hr peak flow 7.4 ft3lsec Pre/Post 1-yr, 24-hr peak flow control 4.7 ft3lsec Basin Elevations Basin bottom elevation 20.00 it Sediment cleanout elevation 21.00 ff Permanent pool elevation 29.00 It Temporary pool elevation 31.00 It Volume and Surface Area Calculations SAIDA ratio 4.90 (unilless) Permanent pool, surface area required 3,630 ffz Permanent pool, surface area provided 3,750 ffz OK Permanent pool volume 16,943 .rya Average depth for SAIDA tables 4 518133333 it OK Forebay volume r 3,389 ff3 Forebay % of permanent pool volume 20 % OK Temporary pool, surface area provided 5,335 ff' Fomn SW401-Wet Detention Basn-Rev.2 Parts I. & 11. Design Summary, Page 1 of 2 �! Permit No. ., (to be Omwded by DWQ) II: DESIGN INFORMATION Drawdown Calculations Treatment volume drawdown time 2.72 _ ,days OK Treatment volume discharge rate 003 'ft3/s Pre -development l-yr,24-hrdischarge ! 272 'ft3/s OK Post -development 1-yr, 24-hr discharge 047 ft3/s OK Additional Information Diameter of orifice 1.00 in Design TSS removal 90 % Basin side slopes 3 :1 OK Vegetated shelf slope 10 :1 OK Vegetated shelf width 10 ft OK Length of gowpath to width ratio 3 :1 OK Length to width ratio 2 :1 OK Trash rack for overflow 6 orifice? Y (Y or N) OK Freeboard provided 2 ft OK Vegetated filter providedv N (Y or N) Design must be based on 90% TSS removal Recorded drainage easement provided? Y (Y or N) OK Capures all runoff at ultimate build -out? Y '(Y or N) OK Drain mechanism for maintenance or emergencies Pump _ -- RECEIVED MAY 0 2 2011 BY: Form SW401-Wet Deienbon Basin-Rev.2 Pans I. a 11 Design Summary, Page 2 of 2 Permit No. 5 LX9 030317 (to be provbed by D;V ) WATF9 �r�44NC��� .•ftaD♦i►ENR y STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information I. PROJECT INFORMATION - - Project name Covil Garderm Contact person Charles Caner Phone number 910 763-5100 Date Drainage area number 1 III. DESIGN INFORMATION Site Characteristics Drainage area 84,076 ff Impervious area 50,928 ff %impervious 60.57376659 % Design rainfall depth 1.5 in Storage Volume: Non -SR Waters Minimum volume required 6,255 to Volume provided 9,516 ft3 Storage Volume: SR Waters 1-yr, 24-hr runoff depth in Pre -development 1-yr, 24-hr runoff ft' Post -development 1-yr, 24-hr runoff it, Minimum volume required ft3 Volume provided ft' Peak Flow Calculations Is prelpost control of the 1-yr 24-hr peak flow required? y (Y or N) 1-yr, 24-hr rainfall depth 3.9 in Rational C, pre -development 0.3 (unitless) Rational C, post -development 0.7 (unitless) Rainfall intensity: 1-yr, 24-hr storm 5.6 in/hr Pre -development 1-yr, 24-hr peak flow 2.7 ft'/sec Post -development 1-yr, 24-hr peak flow 7.4 ft'/sec Pre/Post 1-yr, 24-hr peak flow control 4.7 ft'Isec Basin Elevations Basin bottom elevation 19.00 It Sediment cleanout elevation 20.00 It Permanent pool elevation 29.00 It Temporary pool elevation 31.00 ft Volume and Surface Area Calculations SAIDA ratio 4.37 (unless) Permanent pool, surface area required 3,674 fir Permanent pool, surface area provided 3,992 Ill OK Permanent pool volume 18,297 ft3 Average depth for SAIDA tables 4.583416834 it OK Forebay volume 3,426 ft3 Forebay 0.6 of permanent pool volume 19 % OK Temporary pool, surface area provided 5,524 112 Form SW401-Wet Detention Basm-Rev 2 Parts I. & II. Design Summary, Page 1 of 2 Permit No. 1 W l G$ O"j i% (to be pr Kfed by DWO) II. DESIGN INFORMATION Drawdown Calculations Treatment volume drawdown time 2.76 days Treatment volume discharge rate D.03 W/s Pre -development 1-yr, 24-hr discharge 2.72 h /s Post -development 1-yr, 244 discharge 0.&6 ft'/s Additional Information Diameter of orifice 1.00 in Design TSS removal 90 % Basin side slopes 3 :1 Vegetated shelf slope 10 .1 Vegetated shelf width 10 it Length of 0owpath to width ratio 3 :1 Length to width ratio 2 :1 Trash rack for overflow & orifice? Y (Y or N) Freeboard provided 2 It Vegetated fitter provided? N (Y or N) Recorded drainage easement provided? Y (Y or N) Capures all nmoff at ultimate build -out? Y (Y or N) Drain mechanism for mmntenance or emergencies Pump OK OK OK OK OK OK OK OK OK OK Design must be based on 90%TSS removal OK OK Forth SW401-Wet Detention Basm-Rev.2 Parts I_ & IL Design Summary, Page 2 of 2 PermitNo._SW2 p%oS17 (to be provided by DWQ) Ill ARE UIRED �ITEMS'CHECKLISTf Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Page/ Plan Initials Sheet No. 1. Plans (1- - 50' or larger) of the entire site showing: - Design at ultimate build -out, - Off -site drainage (if applicable), - Delineated drainage basins (include Rational C coefficient per basin), - Basin dimensions, - Pretreatment system, - High flow bypass system, - Maintenance access, - Recorded drainage easement and public right of way (ROW), - Overflow device, and - Boundaries of drainage easement. 2 Partial plan (1" = 30' or larger) and details for the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, - Forebay and main pond with hardened emergency spillway, - Basin cross-section, - Vegetation specification for planting shelf, and - Filter strip. 3. Section view of the dry detention basin (1" = 20' or larger) showing: - Side slopes, 3:1 or lower, - Pretreatment and treatment areas, and - Inlet and outlet structures. - t 4. If the basin is used for sediment and erosion control during construction, dean out of the basin is specified on the plans prior to use as a wet detention basin. COL C` LVL91°U5 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. Cam(( 6. An assurance that the installed system will meet design specifications upon initial operation once the project is complete and the entire drainage area is stabilized. 7. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. i LvLAQciNs 8. The supporting calculations. ��. 0e�(9. A copy of the signed and notarized inspection and maintenance (I&M) agreement. L k 10. A copy of the deed restriction. Form SW401-Wet Detention Basin-Rev.1 Pan 111. Required Items Checklist, Page 1 of t r�, ATA NCDENR Pend Numbef—yuLU�� (to be provided by DWQ) STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM SAND FILTER SUPPLEMENT This form must be filled out on line, printed and submitted with all of the required information. Make sure to also fill out and submit the Required Items Checklist (Section Ill) and the I dM Agreement (Section IV) I. PROJECT INFORMATION Project name Covil Gardens Contact name Phil Tripp, P.E. Phone number 910-763-5100 Date Drainage area number H. DESIGN INFORMATION Site Characteristics Drainage area (AD) Impervious area % Impervious (IA) Design rainfall depth (Ro) Peak Flow Calculations 1-yr, 24-hr runoff depth 1-yr, 24-hr intensity Pre -development 1-yr, 24-hr runoff Post -development 1-yr, 24-hr runoff Pre/Post 1-yr, 24-hr peak control Storage Volume Design volume (WOV) Adjusted water quality volume (WOVE Volume contained in the sedimentation basin and on top of the sand filter Top of sand filter/grate elevation Weir elevation (between chambers) Maximum head on the sedimentation basin and sand fitter (h.,,F�) Average head on the sedimentation basin and sand filter (hA) Runoff Coefficient (Rv) Type of Sand Filter Open sand fifteR SHWT elevation Bottom of the sand filter elevation Clearance (dam) Closed/pre-cast sand filter? SHWT elevation Bottom of the sand filter elevation Clearance (dam) If this is a dosed, underground dosed sand fiker. The clearance between the surface of the sand filter and the bottom of the roof of the underground structure (ds.) May 11, 2011 1 10,000.00 it, OK 8,734.00 ftz 87.3% % 1.50 in 3.90 in 4.87 in/hr 0.28 ft /sec 1.00 ft/sec 0.72 fe/sec 1,047.00 ft3 785.25 ft' OK 790.40 ft 32 it amsl 32.3 ft amsl f, 1.30 ft �asusftsieRFdeptlr. N /r l 0.65 it OK 0.84 (uni8ess) YorN ft amsl ft amsl y YorN 28.50 It amsl 30.50 It artist 2.00 1.80 it CEIVED — 7__ AY 12 2oil Form SW401 Sand Fitter-Rev.5 2009Sept17 Parts I and II. Project Design Summary, Page t of 2 Permit Number: (to be provided by DWQ) Sedimentation Basin Surface area of sedimentation basin (As) Sedimentation basin/chamber depth Sand Filter Surface area of sand filter (AF) Top of sand media fitter bed elevation Bottom of sand media filter bedidrain elevation Depth of the sand media filter bed (dF) Coefficient of permeability for the sand filter (k) Outlet diameter Outlet dischargeMowrate Time to drain the sand filter (t) Time to drain the sand filter (t) Additional Information Does volume in excess of the design volume bypass the sand fitter? Is an off-line flow -splitting device used? If draining to SA waters: Does volume in excess of the design volume flow evenly distributed through a vegetated filter.? What is the length of the vegetated filter? Does the design use a level spreader to evenly distribute flow? Is the BMP located at least 30R from surface waters (50R'rf SA waters)? If not a dosed bottom, is BMP located at least 100R from water supply wells? Are the vegetated side slopes equal to or less than 3:1 Is the BMP located in a recorded drainage easement with a recorded access easement to a public Right of Way (ROW)? What i; the width of the sedimentation chamber/forebay (Wsd)? What is the depth of sand over the outlet pipe (dpipe)? 304.00 ft2 OK. Meets minimum, but may need to be increased to 1.50 It 304.00 ftZ 32.00 it amsl 30.50 it amsl 1.50 it 3.55 (ft/day) 6.00 in 0.91 ft'Isec 0.23 hours OK. Submit drainage calculations. 0.01 days y YorN OK y Y or N OK NIA Y or N Enter Data it YorN y YorN NIA Y or N NIA Y or N Y 4.00 ft 1.50 it OK Enter Data Insufficient vegetated side slopes. YorN OK OK OK MAY 12 Z011 Fonn SW401-Sand Filter-Rev.5 2009Sept17 Parts I and 11. Project Design Summary, Page 2 of 2