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HomeMy WebLinkAbout19960933 Ver 1_Modifications_20080730TfiaaqDesign Group 4807-C Koger Blvd. Greensboro, NC 27407 Phone 336-218-8282 Fax 336-218-8010 at to -b133 TRANSMITTAL LETTER Date: July 29, 2008 To:Annette Lucas N. C. Division of Water Quality Wetlands/401 Certification Unit 2321 Crabtree Boulevard, Suite 250 Raleigh, NC 27604 Project: Mylan Stormwater Ponds Greensboro, NC We Transmit: ( x ) herewith ( ) under separate cover The Following: Copies Date 1 July 29, 2008 1 April 15, 2008 1 July 15, 2008 1 July 15, 2008 1 July 28, 2008 kf?@29161E B JU6 3 0 2008 DENR - WATER QUALITY WETLANDS AND STORMWATER BRANCH Project No.: 08-009/D For Your: ( x) approval ( ) review & comment ( ) use Description Cover Letter Storm Water Plans (to modify existing approved plan) Checklist Wet Detention Basin Supplement (ponds 1 & 2) Operation & Maintenance Agreement (ponds 1 & 2) Remarks: If you have any questions or need additional information, please contact me. Copies: File Sue Homewood Sincerely, By. '4.1?.. -P.4 J. Anthony Lusk, P.E. Civil Engineer P:\2008\Mylan Stormwater Ponds\Wdmin\07-29-08 SW plans to Raleigh DWQ.xmt.wpd Triad' Design Group ARCHITECTURE E N G I N E E R I N G P L A N N I N G I N T E R I O R D E S I G N N PRINCIPALS: Thomas J. Stone Mark J. Davis. PE ASSOCIATES: Rodney M. Lindsey, AIA L. Allan Hill, P.E. Jim 0. White, AIA 0 4807-C Koger Blvd. Greensboro, NC 27407 Telephone 336-218-8282 Fax 336-218-8010 www.triad-designgroup.com July 29, 2008 Annette Lucas N. C. Division of Water Quality Wetlands/401 Certification Unit 2321 Crabtree Boulevard, Suite 250 Raleigh, NC 27604 RE: Mylan Pharmaceuticals Storm Water Modification Greensboro, NC Project no: 08-009/1) Dear Annette, We are requesting to modify the existing, approved storm water plan for the Mylan Pharmaceuticals site. The original approval can be found under DWQ Project #960933. Proposed changes are shown on the accompanying plans. There will be no wetland or stream impacts as a result of this modification. Please feel free to contact me if you have any questions or need more information. Sincerely, J. Anthony Lusk, P.E. Civil Engineer Permit No. g Lo - C 3 3 1 (to be provided by DWQ) v 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. Pagel Plan Initials Sheet No. S,ku 0t lU.l B 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, Proposed drainage easement and public right of way (ROW), Overflow device, and Boundaries of drainage easement. T?,t_ C, 2 • t 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. S(- Cz. + 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. SqL- G1,1It, b U • 6 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified on the plans prior to use as a wet detention basin. 3A, L Pq L?: 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. 'V'L_ t=l •t k , C1 .113 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. . ??L C2? caf e tt%c7. The supporting calculations. SAIL ? 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. 9. A copy of the deed restrictions (if required). l?L 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County soil maps are not an acceptable source of soils information. Form SW401-Wet Detention Basin-Rev.4 Part III. Required Items Checklist, Page 1 of 1 • Permit No. (to be provided by DWQ) i 1 NCDENR ° 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. Project name Contact person Phone number Date Drainage area number A' 4L..h4 Lush (.336) 2- 6t - $L$ Z II. DESIGN INFORMATION Site Characteristics Drainage area ft2 Impervious area ft2 % impervious % Design rainfall depth l,p in Storage Volume: Non-SR Waters Minimum volume required Zk. 347 ft3 Volume provided 6-7)(2-5 ft3 Storage Volume: SR Waters 1-yr, 24-hr runoff depth in Pre-development 1-yr, 24-hr runoff ft3 Post-development 1-yr, 24-hr runoff ft3 Minimum volume required ft3 Volume provided ft3 Peak Flow Calculations 1-yr, 24-hr rainfall depth in Rational C, pre-development (unitless) Rational C, post-development p, g (unitless) Rainfall intensity: 1-yr, 24-hr storm in/hr Pre-development 1-yr, 24-hr peak flow ft3/sec Post-development 1-yr, 24-hr peak flow 1. 20 ft3/sec Pre/Post 1-yr, 24-hr peak flow control ft3/sec Basin Elevations Basin bottom elevation 14 $,p ft Sediment cleanout elevation -t?t9, p ft Bottom of shelf elevation 1St • S ft Permanent pool elevation •15Z• p ft SHWT elevation ft Top of shelf elevation -752.S7 ft Temporary pool elevation -ZSy, p ft Form SW401-Wet Detention Basin-Rev.4 Parts 1. & II. Design Summary, Page 1 of 2 Permit No (to be provided by DWQ) IL DESIGN INFORMATION Volume and Surface Area Calculations i SA/DA ratio 2.5 (unitless) Surface area at the bottom of shelf 23, 005 fts Volume at the bottom of shelf Gi&G(o ft3 Permanent pool, surface area required ?3 5 5o ftZ + Permanent pool, surface area provided 32 000 ft2 Permanent pool volume -2 387- ft3 Average depth for SA/DA tables 3 ft Surface area at the top of shelf ZI.95FS ftz Volume at the top of shelf (gp ft3 Forebay volume 2$p ft3 Forebay % of permanent pool volume j2 A4 Temporary pool, surface area provided _5ft2 _ 35 I2 Drawdown Calculations Treatment volume drawdown time 2.57 days Treatment volume discharge rate 0.5( ft3/s Pre-development 1-yr, 24-hr discharge ft3/s Post-development 1-yr, 24-hr discharge ft3/s Additional Information Diameter of orifice 42) .. y in Design TSS removal gs % Basin side slopes 3 :1 Vegetated shelf slope to :1 Vegetated shelf width ? p ft Length of flowpath to width ratio 2, 3 :1 Length to width ratio 2. 3 :1 Trash rack for overflow & orifice? (Y or N) Freeboard provided 2 ft Vegetated filter provided? V (Y or N) Recorded drainage easement provided? 'Y (Y or N) Capures all runoff at ultimate build-out? Y (Y or N) Drain mechanism for maintenance or emergencies z) - g" prewAs <16 le Dtcmcnt S?eA"yJ ?t Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2 Permit No. t0 ' ° 0, 3 3 (to be provided by DWQ) Please complete the yellow shaded items. of wATF9 v? 7 =AUMV -0 NCDENR ril 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. Project name Contact person Phone number Date Drainage area number (3U) 2.115- $ZFSZ V,j l5, Z6d$ 11. DESIGN INFORMATION Site Characteristics Drainage area )10 ft2 Impervious area 2 2 ft 1714 % impervious % Sg Design rainfall depth - p in Storage Volume: Non-SR Waters Minimum volume required Z(FS 211 ft3 Volume provided ft3 Storage Volume: SR Waters 1-yr, 24-hr runoff depth in Pre-development 1-yr, 24-hr runoff - - ft3 Post-development 1-yr, 24-hr runoff ft3 Minimum volume required ft3 Volume provided ft3 Peak Flow Calculations 1-yr, 24-hr rainfall depth .. 17- in Rational C, pre-development (unitless) Rational C, post-development O . &,47 (unitless) Rainfall intensity: 1-yr, 24-hr storm I ( in/hr L L11 Pre-development 1-yr, 24-hr peak flow _ - ft3/sec Post-development 1-yr, 24-hr peak flow ft3/sec Pre/Post 1-yr, 24-hr peak flow control ft3/sec Basin Elevations Basin bottom elevation - 7 5-f ft Sediment cleanout elevation X357 ft Bottom of shelf elevation 167.5 ft Permanent pool elevation ?13g ft SHWT elevation ft Top of shelf elevation 3?s , 5, 5 ft Temporary pool elevation -7 L4Ci ft ?04_? 71- Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2 t Permit No. (to be provided by DWQ) IL DESIGN INFORMATION Volume and Surface Area Calculations SA/DA ratio 2.33 (unitless) Surface area at the bottom of shelf 4.3l ftZ j o1 Volume at the bottom of shelf , ZSg , 629 ft3 Permanent pool, surface area required Lo?? ftz J Permanent pool, surface area provided I I p p ftZ Permanent pool volume 3i qq ft3 Average depth for SA/DA tables 3 ft Surface area at the top of shelf ?Z( S CFc ftZ Volume at the top of shelf 3 p !o ft Forebay volume (oZ? 3iz ft3 Forebay % of permanent pool volume 21 S % Temporary pool, surface area provided lit 4 ffZ Drawdown Calculations Treatment volume drawdown time 3,$ days Treatment volume discharge rate '1 O ft3/s Pre-development 1-yr, 24-hr discharge ft3/s Post-development 1-yr, 24-hr discharge ft3/s Additional Information Diameter of orifice ( _Z?- (o in Design TSS removal _R5 % Basin side slopes 3 :1 Vegetated shelf slope I:1 Vegetated shelf width ?p ft Length of flowpath to width ratio Length to width ratio Trash rack for overflow & orifice? (Y or N) Freeboard provided Z ft Vegetated filter provided? (Y or N) Recorded drainage easement provided? (Y or N) Capures all runoff at ultimate build-out? (Y or N) Drain mechanism for maintenance or emergencies N-r-kM Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2 Permit Number: ` (.# -DR 33 (to be provided by DWQ) Drainage Area Number: Wet Detention Basin Operation and Maintenance Agreement -RoY"? 1 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 Y does not This system (check one): ? does fA does not incorporate a vegetated filter at the outlet. 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 operation 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: Potential problem: How I will remediate the problem: The entire BMP Trash/ debris is resent. Remove the trash/ debris. The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to detention basin erosive gullies have formed. 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. Form SW401-Wet Detention Basin O&M-Rev.3 Page 1 of 4 Permit Number: (to be provided by DWQ) ?. Drainage Area Number: BMP element: Potential problem: How I will remediate the problem: 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 g. 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. Form SW401-Wet Detention Basin O&M-Rev.3 Page 2 of 4 Permit Number: (to be provided by DWQ) Drainage Area Number: BMP element: Potential problem: How I will remediate the problem: 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 specialist 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 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 be such that it will give an accurate depth reading and not readily penetrate into accumulated sediments. When the permanent pool depth reads -7,_ feet in the main pond, the sediment shall be removed. When the permanent pool depth reads 3 feet in the forebay, the sediment shall be removed. BASIN DIAGRAM ill in the blanks) Permanent Pool Elevation '1$y Sediment Removal Bottom -14 Pe anen Pool ----------------- Volume Sediment Removal Elevation -1149 Volume i l4g -ft Min. --------------------------------------------- - ----Wr Sediment Bottom Elevation 1 1-ft Storage Sedime? FOREBAY Form SW401-Wet Detention Basin O&M-Rev.3 MAIN POND Page 3 of 4 Storage • Permit Number: L (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: IrY 11gy-, ??atmat 2?{icr.(s, the-. BMP drainage area number: Print name: o 'sr.2 R, T .'o w Title: n ,c r --' Z 'L 67,1C Address: '-Z p 5 7 yF.9 L 7,/.4 /-' IC S I D S6 ? N C 17?1O.1 c-X Phone:- Signature: ?5 Date: o Z,/dt 4/o k 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. a Notary Public for the State of , do hereby certify that ?". , County of qaj=j ci?czn? personally appeared before me this day of _ q , and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, JAN A. Sp0? aOTARy?? GI?? UBL%G Z.V ?Rp CpV SEAL My commission expires i yi zn2ll , __'L 6 1 l Form SW401-Wet Detention Basin O&M-Rev.3 Page 4 of 4 Permit Number: Q L# -DR 33 (to be provided by DWQ) Drainage Area Number: Wet Detention Basin Operation and Maintenance Agreement Po,j Z- 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 N does not This system (check one): ? does ® does not incorporate a vegetated filter at the outlet. 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 operation 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: Potential problem: How I will remediate the problem: The entire BMP Trash/ debris is resent. Remove the trash/ debris. The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to detention basin erosive gullies have formed. 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, a roximatel six inches. Form SW401-Wet Detention Basin O&M-Rev.3 Page 1 of 4 Permit Number: (to be provided by DWQ) Drainage Area Number: BMP element: Potential problem: How I will remediate the problem: 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 spraying. 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. Form SW401-Wet Detention Basin O&M-Rev.3 Page 2 of 4 Permit Number: (to be provided by DWQ) Drainage Area Number: BMP element: Potential problem: How I will remediate the problem: 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 specialist 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 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 be such that it will give an accurate depth reading and not readily penetrate into accumulated sediments. When the permanent pool depth reads 3 feet in the main pond, the sediment shall be removed. When the permanent pool depth reads 3 feet in the forebay, the sediment shall be removed. BASIN DIAGRAM ill in the blanks) Permanent Pool Elevation 13$ Sediment Removal Bottom Elevati X35 ? Pe anen? ------------------ Volume '13'1 -ft Min. Sediment Storage FOREBAY Pool -- Sediment Removal Elevation 73$ ............ Volume Bottom Elevation ` *3 1-ft n. Sediment Storage MAIN POND Form SW401-Wet Detention Basin O&M-Rev.3 Page 3 of 4 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:: lcaa, kac mgtpVbm(5, InV. • BMP drainage area number: Print name:7- z- s 4gz M o ,,, Title: 1) ;VjFC7o.Z r_? IC Address: _z F 5 ti, Nv rife maxE,ts .t'u /_',Srf?n,s6<.cc five- .Z7Ya6 Phone: 33,;; yi- 73oa Signature: _?2 Z 111? Date: o/.r y fG Note: The legally responsible party should not be a homeowners aisociation unless more than 50% of the lots have been sold and a resident of the subdivision has been named the president. a Notary Public for the State of _.o ® County of +t , do hereby certify that L 'C personally appeared before me this day of ?, and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, QJA N A SpOr XXOTA 13 L?G v `.ORD COV , SEAL My commission expiresO( e", 114, C-7,16s/ Form SW401-Wet Detention Basin O&M-Rev.3 Page 4 of 4