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HomeMy WebLinkAboutSW8060150_COMPLIANCE_20060508 (2)STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. DOC TYPE El CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE COMPLIANCE EVALUATION INSPECTION DOC DATE �p��l � I WYYMMDD Pennit No. 56U yo(oo f so (to be 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 This form may be photocopied for use as an original DWQ Stormwater Management Plan Review: A complete stormwater management plan submittal includes an application form, a wet detention basin supplement for each basin, design calculations, and plans and specifications showing all basin and outlet stnictiixe detaaZs. ' _ ._.... , .. ,.. ,... .. ............._ . L PROJECT INFORMATION Project Name: 'Sotrttv�ell_ Woo-6 S� h ca t i ntin Contact Person: Phone Number. (et 1 o i 2p2 - (900 For projects with multiple basins, specify which basin this worksheet applies to: _ L3 AIR A ti elevations I�Ijs Basin Bottom Elevation • 1� 3(oPft- Permanent Pool Elevation fL Temporary Pool Elevation ft. areas Permanent Pool Surface Area H o , 3i o s4. ft. Drainage Area S. 1 s ac. Impervious Area . is- ac. volumes Permanent Pool Volume cu. it emporary4PoolyVvlume 33;53� --cu--ft. Forebay Volume Z 75-0 cu. ft. Other parameters SA/DAI Diameter of Orifice Design Rainfall Design TSS Removal Z. Io in. in. Jo % (door of the basin) (elevation of the orifice) (elevation of the discharge structure overflow) (water surface area at the orifice elevation) (on -site and off -site drainage to the basin) (on -site and off -site drainage to the basin) (combined volume of main basin and forebay) rtvo7ume-detain.ed dove the peror) (approximately 20% of total volume) (surface area to drainage area ratio from DWQ table) (2 to S day temporary pool draw -down required) (minimum 85% required) Form SVVU-102 Rev 3.99 Page I of 4 Footnotes: When using the Division SA/DA tables, the correct SA(DA ratio for permanent pool sizing should be computed based upon the actual impervious % and permanent pool depth. Linear 'interpolation should be employed to determine the correct value for non- standard table entries. 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 BMIP manual provides design tables for both 85% TSS removal and 90% TSS removal. II. REQUIRED ITEMS CDECKLLST 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 214.1008. 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 suet, attach justification. Applicants Initials v a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet)- i,J� _ b. The forebay volume is approximately equal to 2001b of the basin volume. l S c- The temporary pool controls runoff from the design storm event_ IWSL-- d. The temporary pool draws down in 2 to 5 days. I1JS'f _ _ e. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow calculations) ESL f_ The basin length to width ratio is greater than 3:1. Lt�SL g. The basin side slopes above the permanent pool are no steeper than 3:1. 4.�SL h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail)- _ L-psL - _ i. Vegetative cover above the permanent pool elevation is specified. _ o, %- j. A trash rack or similar device is provided for both the overflow and orifice. L k. A recorded drainage easement is provided for each basin including access to nearest right- of-way. L L If the basin is used for sediment and erosion control dung construction, clean out of the basin is specified -prior to -use as a wet detention basin. L m. A mechanism is specified cecill drain the basin for maintenance`- - • _ . . ��L�_._....�. - _ ~-- --�ifid which w --- -- -- ---- or an emergency. M. 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 aes no incorporate a vegetated filter at the outlet. This system (check one) 0 does oes no incorporate pretreatment other than a forebay. Form SVVU-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 7517b 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 �feelti�the main pond, the sediment shall be removed. Y. X� ftfw When the permanent pool depth reads feet in the forebay, the sediment shall be removed_ BASIN DIAGRAM (fill in the blanks) Permauent Pool Elevation ` 1L . o Sediment Re oval EL 3'i • Z 75 0 -------------- - Sediment Removal Elevation 3 CJ 75% Bottom Ele ation Up • O %------------- - - 25% FOREBAY MAiN FOND 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 perforin maintenance, the flushing of sediment through the emergency drain shall be minimized to the maximum extent practical. Form SWU-102 Rev 3.99 Page 3 of 4 7. All components of the wet detention basin system sham be maintained in good working order. I acknowledge and agree by my signature below that I am responsible for the performance of the seven maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any charges to the system or responsible party. Print name:_ CG_1K�lC/ Title:_ 2R?:Sn S� `(_ _ . Address: 1 c_M 1 of 6:70 "� f-� C, ,a S 0 � .iZZ�s! Signature: Date:_ 0 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` P c�wl f �% _ a Notary Public for the State of _ , jo Y h ►'� County of 1\j P. VU fla o V j&L" , do hereby certify that V I ' G cSi k k 0 - — personally appeared before me this i � �'`'' day of —2101D, and acknowledge the due execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal, µ. Skit. o 1 SEAT. My commission expires_ Qjjd '57-4t , 20 t 1 Form SVW-102 Rev 3.99 Page 4 of 4 5 Permit No. aAj IF 0(p t 54 (to be 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 71is farm may be photocopiers for use as an original . DWQ Storrnwater Management PIau Review: A complete stor'mwater management plan submitwl includes an application form, a wet detention basin supplement _for each basin" design calculations, and plans. and specifications showing all basin and outlet ..� ........ � __ .. _. L PROJECT INFORMATION Project Name: �J_ W✓ r, e.r W o a s .�u 12C� , Y Contact Person: ; k : kkc, _ Phone Number: (ra 10) 242 -- Z00 For projects with multiple basmi s, specify which basin this worksheet applies to: W.D R 5' 3 elevations Basin Bottom Elevation 33. O ft- Permanent Pool Elevation -59 . O ft. Temporary Pool Elevation Sal It ft. areas Permanent Pool Swface Area (a ` t 13 O sq. ft. Drainage Area -qS-. 7P ac. Impervious Area 13 • G (a ac. volurnes Permanent Pool Volume --empcjo� Volume Forebay VoInme Other parameters SAMA 1 Diameter of Orifice Design Rainfall Design TSS Removal 2 29 2 89 0 cu. ft. co. ft. (floor of the basin) (elevation of the orifice) (elevation of thy: discharge structure overflow) (water surface area at the orifice elevation) (on -site and off -site drainage to the basin) (on -site and off -site drainage to the basin) (combined volu►ne_of pwin.basin and forebay) -(�b�uriie r�etni�a7�ove-the perri�nerif pool) (approximately 20% of total volume) (surface area to drainage area ratio from DWQ table) (2 to 5 day temporary pool draw down required) (minimum 85% required) Form SW-102 Rev 3.99 Page 1 of 4 Footnotes: When using the Division SAIDA tables, the correct SAIDA ratio for permanent pool sizing should be computed based upon the actual impervious % and pennanent pool depth. Linear interpolation should be employed to determine the correct value for non- standard table entries. 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. D. REQU (ZED 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 Stornnwater Managerrxent Permit Application Form, the agent may initial below. If a requirement has not been met, attach justification. Applicants Initials i)s l-- • _ a- The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet). U.2) b. The forebay volume is approximately equal to 20% of the basin volume_ LO c. The temporary pool controls runoff from the design storm event. SL d- The temporary pool draws down in 2 to 5 days. _1> e. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow calculations) �. �. f. The basin length to width ratio is greater than 3: L _ - g. The basin side slopes above the permanent pool are no steeper than 3:1. W h_ A submerged and vegetated perina ter shelf with a slope of 6:1 or less (show detail). i. Vegetative cover above the permanent pool elevation is specified. _lb�_ j_ A trash rack or similar device is provided for both the overflow and orifice. 1AL 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. rn. A J z echariisrn is specified which will drain the basin for maintenance or an emergency. M. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT The wetdetention 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 0 es not This system (check one) 0 does 0 oes not incorporate a vegetated filter at the outlet - incorporate pretreatment other than a forebay. Fonia SWU-102 Rev 3.99 Page 2 of 4 Maintenance activities shall be performed as follows: 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.mai. train a rnaximttm-height-of six. inches; and -remove ifasli as heedet3= 3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc_) quart-;rly to maintain proper functioning_ 4. Remove accumulated sediment fxorn the wet detention basin system semi-annually or when depth is re&ced to 75% of the origiu3al design depth (see diagram below)- Removed sediment shall be disposed of ill an appropriate .manner and shall be handled in a manner that will not adversely impact water quality Ci.e_ stockpling near a wet detention basic or stream.; etc.). 'the measuring device used to determine the sediment elevation: shall be such that it will give an acccu-ate depth Breading and not readily penetrate into accumulated sediments. When the permanent pool depth reads q• S feet in the main pond, the sediment shall be rernoved. Wbm the permanent pool depth reads !Y. 5— feet in the forehay, the sediment shall be removed. BASIN DIAGRAM (fill in the blanks) 0 Permanent Pool Elevation 3 1 Sediment Re oval EL �� S 75 0 ---- Sediment Removal Elevation 75% BottomEle^2s% FOREBAY MAJN POND 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 minin ized to the maxi num extent practical. Forms SWU-102 Rev 3.99 Page 3 of 4 7. All components of the wet detention basin system shall be maintained in good working order. I acknowledge and agree by my signature below that I am responsible for the performance of the seven maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Print name: V; Title: D W n er- Address: PCB S,x r73G5 Wlminct-6 NC 254OC-:;, Phone:_ 2(02 ^ Do Cr IU - 3 g'3 - Z o Signature: _ — Date:�f��3 � Note: The legally responsible party should not be a homeowners association unless more than 50%a of the lots have been sold and a resident of the subdivision has been named the president. _ [`l f1 Q� �f • E—ro I mo- . a Notary Public for the State of 1J0 r,�h CA=�M 1 County of 1I e. W 46 A o vex✓ _ , do hereby certify that w V I C_ personally appeared before me this I '� day of Ai,ayf 4� a , and acknowledge the due execution of the forrgobag wet entiort basin maintenance mquirements. Witness my hand and official seal, 40. Avb� 0 TA f y AVB C, s" VER Go ,.� SEAL My corlmission expires �Giyr, _o?`� . a'-LO 1 Form SWU-102 iRev 3.99 Page 4 of 4 «B» In accordance with Title 15 NCAC 2H.1000, the Coastal Stormwater Management Regulations, deed restrictions and protective covenants are required for High Density Residential Subdivisions where lots will be subdivided and sold and runoff will be treated in an engineered stormwater control facility. Deed restrictions and protective covenants are necessary to ensure that the development maintains a "built -upon" area consistent with the design criteria used to size the stormwater control facility. I, _Vik Sikka , acknowledge, affirm and agree by my signature below, that I will cause the following deed restrictions and covenants to be recorded prior to the sale of any lot: 1. The following covenants are intended to ensure ongoing compliance with State Stormwater Management Permit Number_SW8 060150 as issued by the Division of Water Quality under NCAC 2H.1000. 2. The State of North Carolina is made a beneficiary of these covenants to the extent necessary to maintain compliance with the stormwater management permit. 3. These covenants are to run with the land and be binding on all persons and parties claiming under them. 4. The covenants pertaining to stormwater may not be altered or rescinded without the express written consent of the State of North Carolina, Division of Water Quality. 5. Alteration of the drainage as shown on the approved plan may not take place without the concurrence of the Division of Water Quality. 6. The maximum allowable built -upon area per lot is _4000 square feet. This allotted amount includes any built -upon area constructed within the lot property boundaries, and that portion of the right-of-way between the front lot line and the edge of the pavement. Built upon area includes, but is not limited to, structures, asphalt, concrete, gravel, brick, stone, slate, coquina and parking areas, but does not include raised, open wood decking, or the water surface of swimming pools. 7. All runoff from the built -upon areas on the lot must drain into the permitted system. This may be accomplished through a variety of means including roof drain gutters which drain to the street, grading the lot to drain toward the street, or grading perimeter swales to collect the lot runoff and directi Lsyste nto a component of the stormwater collection system. Lots that will naturally drain into f are not required to provide these additional measures. Signature: Date: 17 n , C4 I (ee rn rh r �1-G�� , a Notary Public in the State of K10041) County of e VV Po_" VZ;' do hereby certify that Vi S4 k ka _._.._.. ,... personally appeared before me this the day of ^ kAau.3(` , 20 00 , and acknowledge the due execution of the foregoing instrument. Witness my hand and official seal, SEAL Sig ture M.,, 5 My Commission expires warn La.� a 4 a D 11` Mif �� A �G �� yqH vg�4Go�},,a CIVET DETENTION POND ANALYSIS PROJECT #: SW8 060150.sepO6 PROJECT NAME: Summerwoods Subdivision Pond 1 Pond 2 Receiving Stream: Middle Swamp Classification: Index Number: Onsite DA, sf= 25.95 Offsite DA, sf = 0.00 Total Drainage Area: 1130382.00 Built -Upon Area Lots, sf= 264000.00 Streets, sf= 90864.00 Clubhouse, sf= SW Other Total Built -upon Area: 354864.00 Surface Area % impervious 31.39% Design Depth, ft: 6.00 TSS (85% or 90%): 90 SA/DA ratio 1.67% Req. Min. Surface Ares 18874 Volume Calculations Design Storm, inches: 1 Rational Cc= 0.44 Rational Volume, cf: 41679 Rv = 0.333 Min. Req. Volume= 31325 Bottom Elevation= 36.00 Permanent Pool Elev= 42.00 Perm Pool Area= 40390.00 Design Pool Elevation= 42.80 Design Pool Area= 43450.00 Total Volume Prov. = 33536.00 Forebay Volume Permanent Pool Vol.= 160170,00 Req. Forebay Volume= 32034 Prov. Forebay Volume: 32750.00 Percent= (22>%>18) 20% KIN 0.00 #DIV/O! #DIV/O! #DIV/O! 1 #DIV/O! #DIV/01 #DIV/O! #DIVI01 0.00 0 #DIV/O! FILE NAME: S:1WQSIPOND1060150.sepO6.WK1 REVIEWER: L. Lewis Original Run Date: July 17, 2006 Last Modified: 26-Sep-06 Pond 3 Pond 4 Pond 5 Pond 6 45.70 0.00 1990692.00 404000.00 162184.00 27000.00 2000.00 595184.00 29.90% 6 90 1.60% 31770 1 0.43 71392 0.319 52933 33.00 39.00 64130.00 39.90 67900.00 59413.50 292890.00 58578 64545 22% 0.00 0.00 0.00 0.00 1 0.00 1 0.00 #DIV/O! #DIV/O! #DIV/O! #DIV/0! #DIV/O! #DIV/O! #DIV/O! #DIV/0! #DIV/0! #DIVIO! #DIV/O! #DIV/O! #DIV/O! #DIVIO! #DIV/O! #DIV/O! #DIV/O! #DIV/0! #DIV/O! #DIV/O! #DIVIO! 0.00 0.00 0.00 0 0 0 #DIV/O! #DIV/O! #DIV/01 { Pond 1 Drawdown OrificetWeir Avg. Head, ft = 0.34 Average Flow Q2, cfs 0.181 Average Flow Q5, cfs 0.073 Q2 Area, sq. in. = 9.33 Q5 Area, sq. in. = 3.73 No. of Orifices 1 Orifice Diameter, in.= 3. Orifice Area, sq. in. = 7.069 Weir Height, inches= Weir Length, inches= Weir C = 11.355 Weir U, eff. length= -0.067 Avg. Flowrate, Q, cfs = 0.137 Drawdown, days = 2.6 Pond 2 Pond 3 Pond 4 Pond 5 Pond 6 0.00 0.37 0.00 0.00 0.00 #DIVIa! 0,306. #DIVIO! #DIV/O! #DIVIO! #DIVIa! 0.123 #DIVIO! #DIVIO! #DIVIa! #DIVIa! 15.13 #DIVIO! #DIVIO! #DIVIO! #DIVIa! 6.05 #DIVIO! #DIV/O! #DIVIO! 1 4 0.000 12.566 0.000 0.000 0.000 #DIVIO! 12.460 #DIVIO! #DIVIO! #DIVIO! 0.000 -0.073 0.000 0.000 0.000 0.000 0.254 0.000 0.000 1 0.000 #DIVIa! 2.4 #DIVIOI #DIVIO! I #DIV/01 0 DESIGN NARRATIVE FOR HIGH DENSITY TREATMENT OF STORMWATER AT SUMMERWOODS SUBDIVISION BOLIVIA, BRUNSWICK CO., N.C. Revised August, 2006 TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION 2.0 SITE DESCRIPTION 3.0 ADJACENT PROPERTY 4.0 DRAINAGE CONSIDERATIONS 5.0 EROSION CONTROL CONSIDERATIONS 6.0 CONSTRUCTION SCHEDULE 7.0 VEGETATION PLAN 8.0 MAINTENANCE PLAN APPENDIX IMPERVIOUS AREA TOTALS STORM PIPING CALCULATIONS DETENTION POND SIZING CALCULATIONS 0 p PE 0=7 a at /ENE Q. 1� 4 0 .SJS 68+'0* 13 Summer Woods Subdivision May, 2006 1. Project Description: The Summer Woods Subdivision is a proposed project to be develop 83 acres from woodland to residential in Bolivia in Brunswick County. The land disturbing activity associated with the project will consist of clearing and grubbing of trees, clearing existing drainage swales, grading of the site, and sediment and erosion control measures such as a silt fence, gravel construction entrance, and wet detention basins. The wet detention basins will act as sediment basins during construction but will be sized for 90% TSS removal of impervious area runoff. Also included in the project will be storm piping, water lines, and sewer lines, and paved roads with curb and gutter. A community area will also be built with clubhouse, tennis, and swimming pool with appropriate parking areas. The total area which will be disturbed for this project is 27.2 acres. 2. Site Description: The project site is in Bolivia, Brunswick Co., NC, located directly to the west of where Galloway Road intersects with Old Ocean Highway, Highway 17 Business. The property on which the development will take place is currently owned by Vik and Ashley Sikka. On site soils consist mainly of Goldsboro and Lynchburg, with some Muckale_e. These soils are mainly loamy, fine sands. There are existing wetlands onsite, approximately 6 acres. New construction onsite will consist of paved roads with curb and gutter, curb inlets, storm piping, and detention ponds. Also included will be a gravity sewer collection system and a water distribution system. General slope of the site is from center to west and east to the wetland areas. Land use in the vicinity is residential and rural agricultural. 3. Adjacent Property: The areas adjacent to the project site are mostly residential areas and rural agricultural. 4. Drainage Considerations: Drainage calculations to determine the size of storm piping is attached in the appendix — Storm Piping Calculations. The project site is graded so that storm water drains into strategically placed curb inlets. From the curb inlets, storm water will empty into a network of storm pipes which drain into several onsite storm water wet detention ponds. The storm pipe network empties into -the detention pond below the -permanent pool elevation. Calculations showing the sizing of the stormwater detention pond are shown in the attached appendix — Detention Pond Sizing Calculations. The ponds are designed to receive a Total Suspended Solids (TSS) removal of 90% and based on 6 foot depth for two ponds and 5' depth on one pond. With 90% TSS there is no need for a vegetative filter. The required temporary storage volume was determined using the Schueler Method and basing calculations on a 1" rainfall event. Then the permanent pool volume is determined based on the permanent pool surface area and the depth of the pool. Then 20% of that volume is to be used for the forebay volume. - Next the orifices were sized at 3" in diameter to keep the drainage time of the 1 inch storm event between 2 and 5 days. A principal spillway was designed to drain storm Summer Woods Subdivision May, 2006 water that rises above the temporary pool elevation. It was sized using the excess runoff created from pre and post development for the 25 year storm. An emergency drainage spillway was sized to handle the same flow as the principal spillway, and will be one foot above the temporary pool elevation. 5. Erosion Control Considerations: The following erosion control measures are used on this project: Temporary Gravel Construction Entrance/Exit To prevent sediment from leaving the site, temporary gravel construction entrances should be installed where the project entrance falls onto Galloway Road. For dimensions and specifications, see construction details. 2. Land Grading The existing slope of the site is from center to west and east towards the back of the property. Most of the disturbed areas on the site will drain into curb inlets which will empty into stormwater piping and drain into onsite detention ponds. 3. Silt Fence Silt fence should be installed prior to clearing and grading activities. Silt fence should be checked routinely. If needed, silt fence should be cleaned and replaced if damaged. See Construction Detail for dimensions and specifications. 4. Inlet Protection Inlet protection consisting of a small portion of silt fence surrounding proposed curb inlets will be utilized to prevent sediment from entering the drainage system. See Construction Detail for dimensions and specifications. 5. Detention Pond Detention ponds will be built to control sediment from leaving the site. See Construction Detail for dimensions and specifications. 6. Temporary Rock Check Dam Rip rap dams constructed at discharge points of the temporary construction ditches. These check dams will serve as temporary sediment traps until the detention ponds are constructed. See Construction Detail for dimensions and specifications. 6. Construction Schedule: 1. Obtain plan approval and other applicable permits. 2. Hold pre -construction meeting at least one ;meek prior to beginning construction. 3. Install temporary construction entrance/exits. 4. Before clearing and grading of the site, install silt fencing and clean and replace as necessary. Summer Woods Subdivision May, 2006 5. Build onsite detention ponds. 6. Check existing swales and clear as necessary. 7. Begin clearing and grading of the site. 8. Construct onsite curb inlets with inlet protection. 9. Install storm piping, 10. Install sewer and waterlines and pave new roadway. 11. All erosion and sediment control practices will be inspected bi-weekly and after each rainfall event. Needed repairs will be made immediately. 12. After the entire covered area is stabilized, all temporary measures will be removed and permanent vegetative repairs to be completed. 7. Vegetation Plan: 1. After complete stabilization of the entire covered area, top cover soils will be roughened by making 1 "-2" deep grooves perpendicular to the slope. 2. Spread lime (agricultural limestone) evenly over the area at a rate of 1.5 tons/acre; spread 10-10-10 fertilizer at a rate of 1000 lb/acre and incorporate into the top 6" of soil. 3. Loosen surface prior to applying seed. 4. Broadcast seed at recommended rates. 5. Rake seed into the soil and lightly pack to establish good contact. 6. Mulch with 4000 Ihlacre grain straw or equivalent and anchor by weighted farm disc set nearly straight or other mulch anchoring tool. 7. Mow as needed and refertilize in late winter or early spring by topdressing with 10- 10-10 fertilizer. 8. Graded surfaces shall not be exposed without grass coverage for more than 15 days._ If grades are not complete and exposure is more than 15 days, temporary seed with rye grain at 50 lb/acre. 8. Maintenance Plan: 1. Contractor shall maintain all sedimentation and erosion control devices during construction. 2. All devices shall be checked after each rain event and weekly. Repairs shall be made immediately when detected. 3. Any deficiencies shall'be brought to the immediate attention of the Engineer. Summer Woods Subdivision May, 2006 Seed Types and Application Rate I Schedule Temporary Seeding Grass Type Amount/ 1000 SF Time of Seeding Initial Rye Grain 1-2 Ibs Nov. —Jan. 25 Ibs 10-10-10 Brown Top Mullet 1-2 Ibs June— Aug. 25 Ibs 10-10-10 Permanent Seeding Grass Type Amount Time of Initial Fertilization 1 Fertilization 1 Fertilization 1 11000 Seeding 1000 sf 1000 sf 1000 sf sf Maintenance maintenance maintenance Burmuda, 1-2 Ibs Apr. - 1 25 Ibs March -April Each 4-8 Aug. -Sept. Common June 10-10-10 12lbs Weeks 12lbs 10-10-10 1-2 Ibs N. 10-10-10 Fescue, Tall 5-7 Ibs Sept. — 25 Ibs Feb -March May & Dec. Sept. -Oct. (Kentucky Oct. 10-10-10 12 Ibs % to 1 lb. n. 12 Ibs 31) Feb. — 10-10-10 10-10-10 Oct. Sericea 1-2 Ibs March — 25 Ibs Feb -March '/2 to 1 lb. N. NIA Lespedeza Apr. 10-10-10 Slo es END OF PLAN Summer Woods Subdivision May, 2006 ;�': . -�'�... L Right Angle Engineering, P.C. DETENTION POND SIZING CALCULATIONS Summerwoods Subdivision Wet Detension Basin #1 Design Drainage Area = 25.95 acres Impervious Area = 8.15 acres Percent Impervious = 31.4% Pond depth = 6 ft TSS removal = 90% SAIDA = 2.10% (No vegetative filter required) Minimum Required Surface Area at Permanent Pooh = 0.021 ' Minimum Required Volume (Schueler Method, see calculations); Rv = 0.05 + 0.000 (31.39) _ Volume = (1"112") 0.333 ' Approx. Permanent Pool Dimensions = ;_ 400.0 ". by Actual Surface Area Provided at PP = 40390 > Need at Least 31325 H3 Elevation of Temporary Pool = 42 + Surface Dims of Temp. Pool = 600 by Actual Surface Area at 42.8 = Temporary Storage Volume Provided = 33536 H3 Forebay Volume - Minimum 20% of Permanent Pool Volume Volume by average area = 40390 sl @ PP Actual Permanent Pool Volrirne = 160170 cf Forebay Volume Required = (.2- 160170 Forebay Depth = 5 ft Surface Area at bottom of forebay(Elev, 37') = 4500 sf Surface Area at top of forebay(Elev. 42') = 3600 sf Forebay Volume Provided = 32750 of Orifice Sizing Q2 = 31325 1 Q5 = 31325 1 Choose a 3" Circular Orifice, Average Head = 0.181 cfs > Choose a 4" Circular Orifice, Average Head = u.181 cfs < Therefore, use a 3" Orifice 25.95 0.3325 25.95 43560 = -23738 @ of storage/ 40390 Therefore, use 0.80 H = 80.00 43450 sf actual vs. design of 43560 = _23738_•„ sf 31325 tt3 40000 sf Elev. 42 it 0,78 ft 0,80 ft 42.8 H 31325 ft' and 13000 SF at bottom = 32034 cf 172800 = 0.181 cfs (Flowrate required for a 2 day drawdown) 432000 = 0.073 cfs (Flowrate required for a 5 day drawdown) a, = 0.06481 a3 = 0,025922 (,80-(112)'(2in112Y2= 0.338 ft dia (in) = 3 a = pi(r^2) 0.0491 sf Q = Ca(2gh)A.5 = 0.1373 cfs 0,1373 cfs > 0.073 cfs (.80-(112)"(4inl12Y2= 0.317 ft dia (in) = 4 a = pi(r'2) 0.08727 sf Q = Ca(2gh)A.5 = 0.23645 cfs 0.2365 cfs - 0.073 cfs Page 1 Right Angle Engineering, P.C. DETENTION POND SIZING CALCULATIONS Summerwoods Subdivision Pre -Development 25 Year Storm by Rational Formula Q=CIA = C= 0.3 1 = 7.14 inlhr To = 10.00 min A = 28.0 ac Q = CIA = 55.61 cfs Post -Development 25 Year Storm by Rational Formula Q=CIA = C = 0.420 1 = 7.14 To = 10.00 A = 26.0 Q = CIA = 77.80 cfs Difference between Pre and Post Development Q = 22.20 cfs Size Outlet Pipe D = 16(Qnifs^.5))^(318 Qpost = 77.80 cfs s = 0.75% n = 0.013 D (theoretical) = 40.2 in D (actual) = 42.0 in Size Emergency Spillway impervious 0.00% pervious = 100.00% I (in/hr) = g/(h+T) for T=5 to 120 minutes impervious 31.39% pervious= 68.61% 1 fin/hr) = g/(h+T) for T=5 to 120 minutes _ Channel Lining: Rip Rap n= 0.030 1.00 ft. 1 S= 1.00% 3 Q Mannings (cfs)= 104.12 Max --20.0 ft-� Length= 20 ft Velocity-- 4.53 fits Depth with Freeboard= 1.00 ft Page 2 .0 Right Angle`Ertgineering, P.C. DETENTION POND SIZING CALCULATIONS 9/22/2006 Summerwoods Subdivision Wet Detension Basin #3 Design Drainage Area = 45.70 acres DA-2 plus DA-3 Impervious Area = 13,66 acres DA-2 plus DA-3 Percent Impervious = 29,9% Total Combined Pond depth = 6 ft TSS removal = 90% SA/DA = 1.60% (No vegetative filter required) Minimum Required Surface Area at Permanent Pool: 0.016 45.70 Minimum Required Volume (Schueler Method, see calculations): Rv = 0.05 + 0.009 (29.89) = 0,3190 Volume = 0"112 ) 0.319 45.70 43560 = Approx. Permanent Pool Dimensions = 480.0 by 125.0 = Actual Surface Area Provided at PP = 64130 > 31851 @ Need at Least 52918 ft3 of storage/ 64130 Therefore, use Elevation of Temporary Pool = 39 f 0.90 h = Approx. Surface Dims of Temp. Pool = 600 by 125.00 avg. Actual Surface Area(by CAD) at 39.9 = 67900 sf Temporary Storage Volume Provided = 59414 ft3 actual vs. design of: Forebay Volume - Minimum 20% of Permanent Pool Volume 43560 = �`,31851" sf 52918 ft' 60000 ' sf Elev. 39 it 0.83 it 0.90 ft 39.90 ft 52918 ft' Volume by average area = 64130 sf @ PP and 33500 SF at bottom Actual Permanent Poo$ Volume = 292890 cf Forebay Volume Required = (.2' 292890 } = 58578 cf Forebay Depth = 5 It Surface Area at bottom of forebay(Eiev, 33') = 7600 sf Surface Area at top of forebay(Elev, 39') = 18218 sf Forebay Volume Provided = 64545 of Orifice Sizing Cie = 52918 ! 172800 = 0.306 cis (Flowrate required for a 2 day drawdown) Q5 = 52918 ! 432000 = 0.122 cfs (Flowrate required for a 5 day drawdown) az = 0.10217 85 = 0.040869 Choose a 3" Circular Orifice, Average Head = (.90-(112)'(2in112)12 = 0.388 ft dia (in) = 3 a = pi(r^2) 0.0491 sf Q = Ca(2gh)^,5 = 0.1471 cfs 0.306 cfs > 0.1471 cfs > 0.122 cfs Choose a 4" Circular Orifice, Average Head = (.90-(1/2)'(4in112)12 = 0.367 ft dia (in) = 4 a = pi(r^2) 0.08727 sf Q = Ca(2gh)^.5 = 0.25444 cfs 0.306 cfs > 0.2544 cfs > 0.122 cfs Therefore, use a 4" Orifice RECEIVED SEP 2 2 2006 DWQ PROJ # 0 jr S PE 7 .��. t �5)Fa ` a �'°ANE L1 ,,# zz _� 6 04*1P r a 0";° o q Page 1 1 Right Angid Engineering, P.C. DETENTION POND SIZING CALCULATIONS 9/2212006 Summerwoods Subdivision Pre -Development 25 Year Storm by Rational Formula Q=CIA = C = 0.3 1 = 7.14 inlhr Tc = 10.00 min A = 45.7 ac Q = CIA = 97.93 cfs Post -Development 25 Year Storm by Rational Formula Q = CIA = C = 0.409 1 = 7.14 Tc = 10.00 A = 45.7 Q = CIA = 133.58 cfs Difference between Pre and Post Development Q = 35,65 cfs Size Outlet Pipe D = 16(Qnf(s".5))A(3iB) Qpost = 133.58 cfs S = 0.50% n = 0.009 D (theoretical) = 46.3 in D (actual) = 48.0 in Size Emergency Spillway impervious 0.00% pervious= 100.00% I fin/hr) = gl{h+T) for T=5 to 120 minutes impervious 29.89% pervious= 70.11% I (in/hr) = g/(h+T) for T=5 to 120 minutes _ Channel Lining: Rip Rap n= 0.030 1.0 1 S= 1.00% 3 Q Mannings (cfs)= 79.63 Max �15.0 f!—►� Length= 15 ft Velocity-- 4.42 ftls Depth with Freeboard- 1.00 ft Page 2 Outlet Protection Sizing Q (flowrate) Depth (ft) Do (in) La (ft) W (ft) 3`Do (ft) Outlet Protection - Into Detention Pond 1 38.90 1 30 15 17.50 7.5 Outlet Protection - Out of Detention Pond 1 77.80 1.5 42 25 28.50 10.5 Outlet Protection - Into Detention Pond 2 29.59 1 30 15 17.50 7.5 Outlet Protection - Out of Detention Pond 2 59.18 1 36 25 28.00 9.0 Outlet Protection - Into 37.21 1 30 15 17.50 7.5 Detention Pond 3 Outlet Protection - Out 133.60 1.5 43 30 34.00 12.0 of Detention Pond 3 3'Do W =Do+La 1