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Home My WebLink About20001195 Ver 12_Stormwater Info_20120504ONE COMPANY I—DR Many Solutions 10fl-1IQs U12, Transmittal Attention Annette M Lucas PE Date 5/2/12 Job No 100062 75476 018 Environmental Engineer To NCDENR I DWQ I Wetlands and Stormwater Branch Phone 919) 807 6375 1650 Mail Service Center Raleigh NC 27699 1650 Regarding CDIA SWN P West Blvd We are sending you ® Attached ❑ under separate cover via — the following Items ❑ Shop drawings ❑ Prints ® Plans ❑ Samples ❑ Specifications ❑ Copy of Letter ❑ Change Order ® Reports ❑ CDs ❑ Other _ Copies Date No Description 3 4/18/12 1 Updated Geotechnlcal Report 3 5/2/12 2 Bloretentlon Cell Supplements and Calculations 3 5/2/12 3 New Sheet 14A, 14B and 6A of SWMP Colored Plans 1 5/1/12 Letter responding to recent comments oil Q9 MAY �ww These are transmitted as checked below ® For approval ❑ Approved as submitted ® For your use ❑ Approved as noted ® As reque e,+ ❑ Returned for mrrPctions For review /comment ❑ Other_ ror Dias aue — Remarks Enclosed are only the updated documents If enclosures are not as noted please notify us at once C %pwwork ngl pa d03737 7aransmittal Form20 »0502 dor HDR E -Igmearing In of the Carolinas Employee -owned ® Resubmit 3 copies for approval ❑ Submit _ copies for distnbution Fj Return M corrected prints P,irts t m d of +er ioa }o is Ronald A Geiger PE 128 S Trvon Street Suite 1400 I Telephone (704) 338 6700 Charlotte NC 18tU2 5004 I Fax t7041 3 8-6760 May 1 2012 Annette M Lucas PE Environmental Engineer NCDENR I DWQ I Wetlands and Stormwater Branch 1650 Mail Service Center Raleigh NC 27699 1650 Re Charlotte Douglas International Airport s (CDIA) UT to Coffey Creek [0308834,11 137 4 C] Dear Ms Lucas ECEIVE MAY 4 2012 On April 13 1212 HDR Engineering Inc of the Carolinas received a letter from the Division of Water Quality (DWQ asking for additional information regarding the CDIA s Modified Storm Water Management Plan (SWMP) specifically the addition of the West Blvd project to the plan Attached are the relevant documents which constitute our previous Express Review Stormwater Management Plan submittal package for the above referenced project The following addresses your questions in the letter Bioretention Cell #1 The bioretentzon cell is still sloped on the plan anew of sheet 14A Bioretention cells must be flat throughout their section to function properly a Plan has been adjusted to comply Both Bioretention Cells 1 The plans still show ponding of 18 Pondzng shall not be greater than 12 Please revise a Plan has been adjusted to comply 2 Anon Oe,M agreemem form must be sub mz�fied Only a photocopy of the sgratu� page was submitted It can be downloaded from bgp /[portal ncdenr oal web /wq/su/bmp ch12 d A-i or giria' O&M agreement va sabmitted Tt has been located by Robert Patterson 3 The SHWT elevation determination should be bases on a soil boring that looks for mottling of the soil that results from mineral leaching The use of a pie�ometer for a single day w 1lonly provide you with what elevation of the water table is on thatgiven day not the seasonal high water table elevation a Additional information is provided in the re submittal to reflect SHWT eievauon data received dt eacil BMP'ocatio -i HDR Engineering inc of the Carolinas 440 S Church Street Phone (7041338 6700 Suite 1000 fax (704) 338 6760 Charlotte NC 28202 2075 www hdrtnc com Page 2 of 2 4 Please he sure that any changes are consistently reflected on all documents (plans calcs and forms) a Calculation sheets have been updated If you have any questions concerning the information in this letter or need additional information please feel free to contact me at (704) 338 6825 Sincerely HDR Engineering, Inc of the Carolinas r Ronald A Geiger PE Project Manager cc Jack Christine CDIA Jimmy Jordan CDIA HDREng neering in aitheCarchnas STORM WATER MANAGEMENT PLAN AREA WEST OF 2ND PARALLEL RUNWAY CharlotteeDou las g INTERNATIONAL AIRPORT REVISED OCTOBER 24 2008 UPDATED MARCH 1 2012 UPDATED MAY 2, 2012 PREPARED BY @@@g� TALBERT& BRIGHT MAY 4 2012 4944 Parkway Plaza Boulevard SUITE 350 Charlotte NC 28217 A R� 704 426 6070 aee• ee,►q, 704 426 6080 (FAX) HDR ONE COMPANY I Many Solutions 440 South Church St, Suite 1000 1 Charlotte, NC 128202 5004 Phone 704 973 6889 1 Fax 704 338 6760 STORM WATER MANAGEMENT PLAN AREA WEST OF 2ND PARALLEL RUNWAY Charlotte im Doug INTERNATIONAL AIRPORT REVISED OCTOBER 24 2008 UPDATED MARCH 1 2012 UPDATED MAY 2, 2012 waes�,�►.,� e•••.••'�jp �e PREPARED BY ° GIs TALURT& hRIGH_[ 4944 Parkway Plaza Boulevard SUITE 350 0� Charlotte NC 28217 tv"If##0001 704 426 6070 704 426 6080 (FAX) HDR ONE COMPANY I Many Solutions 440 South Church St Suite 1000 1 Charlotte NC 128202 5004 Phone 704 973 6889 1 Fax 704 338 6760 ATAboa w rFq NWEHR0 STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM BIORETENTION CELL SUPPLEMENT This form must be filled out pnnted and submitted The Required Items Checklist (Part Ill) must be punted filled out and submitted along with all of the required I PROJECT INFORMATION Project name Charlotte Douglas International Airport Contact name Ron Geiger Phone number 704 338 6825 Date May 2012 Drainage area number L14 (Bio #2) II DESIGN INFORMATION Site Characteristics Drainage area 199 543 ft Impervious area 45142 ftz Percent impervious 226% ova Design rainfall depth 10 inch Peak Flow Calculations Is pre /post control of the 1 yr 24 hr peak flow required? N (Y or N) 1 yr 24 hr runoff depth in 1 yr 24 hr intensity in /hr 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 control ft3 /sec Storage Volume Non SA Waters Minimum volume required 1 715 9 ft3 Volume provided 1 740 00 ft3 OK Storage Volume SA Waters n/a 15 runoff volume ft3 Pre development 1 yr 24 hr runoff ft3 Post development 1 yr 24 hr runoff ft3 Minimum volume required 0 ft3 Volume provided ft3 Cell Dimensions Ponding depth of water 12 inches OK Pondmg depth of water 100 ft Surface area of the top of the bioretention cell 1740 00 f 2 OK Length 58 00 ft OK Width 30 00 ft OK or Radius ft Media and Sods Summary Drawdown time ponded volume 8 hr OK Drawdown time to 24 inches below surface 16 hr OK Drawdown time total 24 hr In situ soil y (Y or N) OK Sod permeability 0 60 in /hr OK Planting media sod 702 5 fmsl Sod permeability 150 in /hr OK Sod composition installing grassed cell % Sand (by volume) 85% OK % Fines (by volume) 10% OK % Organic (by volume) 5% OK Are underdrams being installed? Total 100% Phosphorus Index (P Index) of media (urntless) OK Basin Elevations Temporary pool elevation 703 50 fmsl Type of bioretention cell (answer Y to only one of the two following questions) Is this a grassed cell? y (Y or N) OK Is this a cell with trees /shrubs? (Y or N) Planting elevation (top of the mulch or grass sod layer) 702 5 fmsl Depth of mulch 017 inches Insufficient mulch depth unless installing grassed cell Bottom of the planting media sod 699 35 fmsl Planting media depth 315 ft Depth of washed sand below planting media sod 0 33 ft Are underdrams being installed? Y (Y or N) How many clean out pipes are being installed? 4 OK What factor of safety is used for sizing the underdrams? 10 OK (See BMP Manual Section 12 3 6) Additional distance between the bottom of the planting media 1 ft and the bottom of the cell to account for underdrams Bottom of the cell required 698 02 fmsl SHWT elevation 696 fmsl Distance from bottom to SHWT 2 02 ft OK Internal Water Storage Zone (IWS) Does the design include IWS Elevation of the top of the upturned elbow Separation of IWS and Surface Planting Plan Number of tree species Number of shrub species Number of herbaceous groundcover species Additional Information Does volume in excess of the design volume bypass the bioretention cell 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 30 feet from surface waters (50 feet if SA waters)? Is the BMP located at least 100 feet from water supply wells? Are the vegetated side slopes equal to or less than 31 Is the BMP located in a proposed drainage easement with access to a public Right of Way (ROW)? Inlet velocity (from treatment system) Is the area surrounding the cell likely to undergo development in the future? Are the slopes draining to the bioretention cell greater than 20 %? Is the drainage area permanently stabilized? Pretreatment Used (Indicate Type Used with an X in the shaded cell) Gravel and grass (8inches gravel followed by 3 5 ft of grass) Grassed swale Forebay Other Y (Y or N) 699 81 fmsl 2 69 ft OK Y (Y or N) OK N (Y or N) Excess volume must pass through filter ft N (Y or N) Show how flow is evenly distributed Y (Y or N) OK Y (Y or N) OK N (Y or N) Insufficient vegetated side slopes Y (Y or N) OK 15 ft/sec Insufficient inlet velocity unless energy dissipating devices are being used N (Y or N) OK N (Y or N) OK Y (Y or N) OK M 501.1 NOTES The 10 year design storm flow is evenly distributed through weirs leaving the forbay and entering the bioretention basins The basin has a 24 ft weir leaving the basin An additional weir is located at the end of the forebay for higher storms The side slopes are 21 do to the steep terrain The inlet velocity from the forbay is entering a biorentention basin that is using grass for its pollutant removal Per chapter 8 of the BMP manual filter strips are not required for bioretention cells and per conversation with R Patterson no action is required Permit No (to be assigned by DWQ) A� 0F WA Llz O NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM BIORETENTION CELL 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 Charlotte Douglas International Airport Contact name Ron Geiger Phone number 704 338 6825 Date Drainage area number II DESIGN INFORMATION Site Characteristics May 2012 Y2 (Bio #1) Drainage area 445 589 0 ftz Impervious area 34 848 0 ff Percent impervious 78% % Design rainfall depth 10 inch Peak Flow Calculations Is pre /post control of the 1 yr 24 hr peak flow required? N (Y or N) 1 yr 24 hr runoff depth in 1 yr 24 hr intensity In /hr 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 control ft3 /sec Storage Volume Non SA Waters Minimum volume required 4 470 2 ft3 Volume provided 4 500 0 ft3 Storage Volume SA Waters 15 runoff volume ft3 Pre development 1 yr 24 hr runoff ft3 Post development 1 yr 24 hr runoff ft3 Minimum volume required 0 ft3 Volume provided ft3 OK Form SW401 Bioretention Rev 3 Part III Page 1 of 3 Form SW401 Bioretention Rev 3 Part III Page 2 of 3 Permit No (to be assigned by DWQ) Cell Dimensions Pondmg depth of water 12 inches OK Pondmg depth of water 100 ft Surface area of the top of the bioretention cell 4500 0 ft2 OK Length 300 0 ft OK Width 15 0 ft OK or Radius ft Media and Sods Summary Drawdown time ponded volume 8 hr OK Drawdown time to 24 inches below surface 16 hr OK Drawdown time total 24 hr In situ soil Sod permeability 0 60 In /hr OK Planting media soil Sod permeability 150 In /hr OK Soil composition % Sand (by volume) 85% OK % Fines (by volume) 10% OK % Organic (by volume) 5% OK Total 100% Phosphorus Index (P Index) of media (umtless) Basin Elevations Temporary pool elevation 710 5 fmsl Type of bioretention cell (answer Y to only one of the two following Is this a grassed cell? Y (Y or N) OK Is this a cell with trees /shrubs? N (Y or N) Planting elevation (top of the mulch or grass sod layer) 709 5 fmsl Depth of mulch 017 inches Insufficient mulch depth unless Bottom of the planting media sod 706 33 fmsl Planting media depth 317 ft Depth of washed sand below planting media sod 0 3 ft Are underdrams being installed? Y (Y or N) How many clean out pipes are being installed? 8 OK What factor of safety is used for sizing the underdrams? (See BMP 10 OK Additional distance between the bottom of the planting media and the 1 ft Bottom of the cell required 705 0 fmsi SHWT elevation 698 fmsl Distance from bottom to SHWT 7 0 ft OK Form SW401 Bioretention Rev 3 Part III Page 2 of 3 Internal Water Storage Zone (IWS) Does the design include IWS Elevation of the top of the upturned elbow Separation of IWS and Surface Planting Plan Number of tree species Number of shrub species Number of herbaceous groundcover species Additional Information Does volume in excess of the design volume bypass the bioretention 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 30 feet from surface waters (50 feet if SA Is the BMP localed at least 100 feet from water supply wells? Are the vegetated side slopes equal to or less than 31? Is the BMP located in a proposed drainage easement with access to Inlet velocity (from treatment system) Is the area surrounding the cell likely to undergo development in the Are the slopes draining to the bioretention cell greater than 20 %? Is the drainage area permanently stabilized? Pretreatment Used Gravel and grass Grassed swale Forebay Other Permit No (to be assigned by DWQ) Y (Y or N) 706 79 fmsl 2 7 ft OK Y (Y or N) OK N (Y or N) Excess volume must pass through filter ft N (Y or N) Y (Y or N) Y (Y or N) N (Y or N) Y (Y or N) 19 ft/sec N (Y or N) N (Y or N) Y (Y or N) Y Show how flow is evenly distributed OK OK Insufficient vegetated side slopes OK Insufficient inlet velocity unless energy OK OK OK NOTES The 10 year design storm flow is evenly distributed through weirs leaving the forbay and entering the bioretention basins and the bypass weir leaving the end forebay The basin has a 40 ft weir leaving the basin An additional weir is located at the end of the forebay for higher storms The side slopes are 21 do to the limited space The inlet velocity from the forbay is entering a bioretention basin that is using grass for its pollutant removal Per chapter 8 of the BMP manual filter stnps are not required for bioretention cells and per conversation with R Patterson no action is required Form SW401 Bioretention Rev 3 Part III Page 3 of 3 22 February 2012 18 April 2012 — Revision 1(addition of sod profile details) Introduction In order to obtain groundwater and limited hydrogeological data with respect to proposed bio retention basin siting areas (specifically the determination of a seasonal high water table SHWT) along West Boulevard the Charlotte Douglas International Airport Environmental Affairs Manager Mr Jimmy D Jordan contracted with Probe Technology Inc a licensed North Carolina Well Driller to conduct a limited subsurface investigation at the site(s) of the proposed basins The sites of the proposed basins are shown on those drawings prepared and held by HDR Engineering Charlotte North Carolina Investigation On February 21 2012 Probe Technology a North Carolina Licensed Well Driller Concord NC arrived at the two areas shown on the attached figure and installed a 15 foot piezometer at each location denoted (BR 1 and BR 2) The piezometer probe points were constructed by use of a DT 66 Geoprobe track mounted Direct Push vehicle driving 2 75 diameter hollow push point tooling Soil samples were collected continuously at each location from the ground surface to a depth of approxmately 15 feet below grade level (BGL) The samples were collected in disposable acetate liners Once procured from the tooling strand the samples were observed and the lithology recorded by Mr Jordan a North Carolina Licensed Geologist The resultant lithologic descriptions from this work are included as Figures 1 and 2 Upon completion of each piezometer the % inch PVC well material was installed into the borehole and constructed as a temporary water level monitoring device A 10 foot long 010 slotted screen section was installed from the bottom of the hole up to an elevation of 5 feet below ground level (BGL) and each well was completed flush to the ground surface by the addition of a 5 foot PVC riser with a compression fitting cap A sand filter pack was placed around the screen section of each piezometer Results Soil Profiles Soil profiles at BR 1 indicated micaceous reddish brown sandy silt to a depth of approximately 14 feet Although the sand became more coarse and abundant with increasing depth no mottling was observed and no characteristics of a water table were apparent The profile from BR 1 indicated moisture and damp conditions at approximately 13 feet BGL Approximately 1 hour after installation of the BR 1 a disposable PVC bailer was lowered into the well to check for the presence of water A measurable volume of water was present in the bailer and the depth to water was initially measured by a water level detection device as being approximately 13 4 feet BGL The observations for the soil profile at BR 2 showed reddish brown slightly sandy becoming tan in color and silty at around 10 feet From 10 to 15 feet the soil was tan to deep brown with medium to coarse silt with some mica feldspar and silica (quartz) This saprolite as appropriately called showed no indication of a fluctuating or seasonal high water table at any portion of the interval There was no significant moisture and only moist conditions at approximately 11 feet BGL Approximately 1 hour after installation of the piezometer a disposable PVC bailer was lowered into the well to check for the presence of water No water was present in the bailer and a static water table surface was not evident when checked with a water level detection device 24 hour check Approximately 24 hours after installation Mr Jordan returned to both BR 1 and BR 2 to check for the presence of groundwater At location BR 1 no groundwater had collected into the piezometer and no measureable amount of water could be collected by the bailer Likewise at location BR 2 no groundwater had collected into the piezometer and no measurable water could be collected into the bailer Conclusions Despite the occurrence of water initially seen at location BR 1 it is the opinion of this investigation that the depth to the shallow water table or surficial aquifer (SHWT) is greater than 12 feet Within 36 hours prior to the investigation a measurable and prolonged rainfall event had occurred and it is likely that the water initially collected into the well bore was from percolating precipitation through the upper soil column and not representative of a surficial aquifer or static permanent groundwater condition Assuming the piezometer had been installed and screened into the static water table then the well would have supplied water as it was being bailed or pumped which it did not Thus this well was dry on the morning of the 22nd AT location BR 2 there was no measurable groundwater penetrated by the installation of the piezometer It is therefore the professional opinion of the Geologist that the suf►c►al water table at this location averages (throughout the year) is greater than 12 feet below the surface Based on the observations made the seasonal high water table is also greater than 12 feet below ground surface Limitations The findings conclusions opinions and observations expressed in this report are relative to those activities conducted and those site conditions which existed at the time and date of the investigation and location of the field investigations with respect to the measurements made No warranties are made written or implied with respect to site conditions specifically including geological and hydrogeological conditions that may exist elsewhere in the same geographical locale or that may have existed at different times before or after the investigations were made All measurements expressed in this report should be considered approximate Jimmy D Jordan P G North Carolina Licensed Geologist #1777 NOTES: 1' CONTRACTOR TO INSTALL STONE D| CHECKS, AS DIRECTED BY INSPECTOR, FOR EROSION CONTROL. 2' CONSTRUCT ALL DIVERSION DITCHES PRIOR TO INSTALLATION OF B|C)RETENTlON BASIN. 3' UNDERDRA|N PIPES TO BE SCHEDULE 40 PVC. ALL DRAIN PIPES SHALL BE PERFORATED EXCEPT DISCHARGE PIPE. DISCHARGE PIPE T0 BE SOLID. 4' CONTRACTOR TO BUILD E3|(]RETENllON BASIN TO COMPLY GENERALLY WITH THE SHAPE ILLUSTRATED AND TO MAINTAIN 1920 S.F. OF SURFACE AREA. -- - 5, CONTRACTOR SHALL BE PROHIBITED, FROM USING SOD THAT IS GROWN IN SOIL THAT HAS AN IMPERMEABLE LAYER /SUCH AS CLAY). SOD SHALL BE KENTUCKY 31 TALL FESC�Z 1310—KLILN(|QN b8b|N EXISTING PAVEMENT PROPOSED CLEANDUT —~~-~-~~~~~— PROPOSED UNDERDRA|N �� TRANSVERSE VIEW w�o��pnm��m� *�—�� "r-,`^^ ,.,`'_-7f%=, 30, | �-' '`01 ' ' f\ Y _ . _�, -' U N PIPE TURN ' (SEE SECTION AA\ / / _ ~~' LONGITUDINAL VIEW / / TIE |N SECTION A-A EXIT WEIR , BERM NOT TO SCALE Fa ELEV.=703.5' 51 !c' ' ENTRANCE WEIR 12 OUT PIPES PONDING FILL MEDIA 85% SAND 10% FINES 5% ORGANIC 24 3" UNDERDRAIN PIPE TURN NTH PVC TIE Il BENDS AS REQUIRED. ELEV. 701.5' TOP BEND INV.=699.81 LELEV. 702.5-- 3' FILL MEDIA FILTER FABRIC DIA. UNDERDRAIN ELEV. 699.35 1-4- OUT ELEV.=E STONE 4�' DI A. UNDERDRAIN DISCHARGE PIPE LS ELEV. 698.35'—"" 15' —15. _15'_ 5f 4" DIA. UNDERDRAIN DISCHARGE PIPE 58' | L_M.A NOTES: 1' CONTRACTOR TO INSTALL STONE D| CHECKS, AS DIRECTED BY INSPECTOR, FOR EROSION CONTROL. 2' CONSTRUCT ALL DIVERSION DITCHES PRIOR TO INSTALLATION OF B|C)RETENTlON BASIN. 3' UNDERDRA|N PIPES TO BE SCHEDULE 40 PVC. ALL DRAIN PIPES SHALL BE PERFORATED EXCEPT DISCHARGE PIPE. DISCHARGE PIPE T0 BE SOLID. 4' CONTRACTOR TO BUILD E3|(]RETENllON BASIN TO COMPLY GENERALLY WITH THE SHAPE ILLUSTRATED AND TO MAINTAIN 1920 S.F. OF SURFACE AREA. -- - 5, CONTRACTOR SHALL BE PROHIBITED, FROM USING SOD THAT IS GROWN IN SOIL THAT HAS AN IMPERMEABLE LAYER /SUCH AS CLAY). SOD SHALL BE KENTUCKY 31 TALL FESC�Z 1310—KLILN(|QN b8b|N EXISTING PAVEMENT PROPOSED CLEANDUT —~~-~-~~~~~— PROPOSED UNDERDRA|N �� TRANSVERSE VIEW w�o��pnm��m� *�—�� "r-,`^^ ,.,`'_-7f%=, 30, | �-' '`01 ' ' f\ Y _ . _�, -' U N PIPE TURN ' (SEE SECTION AA\ / / _ ~~' 20 10 0 20 40 60 SCALE IN FEET L-4 , � 7 C8`��o�/ON PROPOSED -~ ~`~``~ DITCH / APPROXIMATE FUTURE / FILL SLOPE TIE |N/ ` ' � LOCATION / - vn* / ��~ ^ ' \ ^^*` _`- � \+' ' \ ,~ / JL1-4 (Blo #2)1 Will, E IN / / ' ' ' !c' ' 20 10 0 20 40 60 SCALE IN FEET L-4 , � 7 C8`��o�/ON PROPOSED -~ ~`~``~ DITCH / APPROXIMATE FUTURE / FILL SLOPE TIE |N/ ` ' � LOCATION / - vn* / ��~ ^ ' \ ^^*` _`- � \+' ' \ ,~ / JL1-4 (Blo #2)1 Will, E IN mill TIE IN 0.0% 5' 1 1 5'-" --1 o'--v- 4!' DIA. UNDERDRAIN —75 '_75' _75'— DISCHARGE PIPE I— - 300' B NOTES: 1. CONTRACTOR TO INSTALL STONE DITCH CHECKS, AS DIRECTED BY INSPECTOR, FOR EROSION CONTROL. 2. CONSTRUCT ALL DIVERSION DITCHES PRIOR TO INS_"?;LLATION OF BIORETENTION BASIN. 3. UNDERDRAIN PIPES TO BE SCHEDULE 40 PVC, ALL DRAIN PIPES EXCEPT DISCHARGE PIPE SHALL BE PERFORATED. DISCHARGE PIPE SHALL BE SOLID WALL. 4. CONTRACTOR TO BUILD BIORETENTION BASIN TO COMPLY GENERALLY WITH THE SHAPE ILLUSTRATED AND TO MAINTAIN 4.490 S.F. OF SURFACE AREA. 5. CONTRACTOR SHALL BE PROHIBITED FROM USING S00 THAT IS GROWN IN SOIL THAT HAS AN IMPERMEABLE LAYER (SUCH AS CLAY). SOD SHALL BE KENTUCKY 31 TALL FESCUE. LEGEND BIO-RETENTION BASIN EXISTING PAVEMENT PROPOSED CLEANOUT PROPOSED UNDERDRAIN SECTION B-B NOT TO SCALE TIE IN OVERFLOW WEIR El FV.=710.5" UhIDERDRAIN INV. ELEV.= 708.5' OUT El FV.=7049 I L 3' FILL MEDIA TIE IN I BERM ELEV.=71 4" DIA. CLEAN OUT PIPES WITH SCREW CAPS 1 893 8" STONE 5A \\-4" DIA. UNDERDRAIN PIPE 5'— 15' A—] \7--i 5' A--� EXISTING PIPE ------ ---EX: I NV_-OUT ::�- 7TG -INV OUT=711.5 PROP. 15 LF OVERFLOW WEIR :ue.-xi 7 0e, X _710— -7 -7 1 7'1 o. 5 EXISTING COT DITCH ......................... ""n —71 .0 . .. . ....... '710.5 '7 Al2- og ROW— ROW— ROW— ROW ROW—, ROW— ROW— ROW ROW— ROW,— ROW— ROW— ROW— F?nw—L OVERFLOW WEIR ELEV.= 710.5' , 2 � 1 20 10 0 20 40 61 SCALE IN FEET V$=2C LOT TIE IN TALBERT&BRIGHT ENGRGERING 6L PLANNING CONSULTANTS rj 4944 PAPJCWAY PLAZA BOULEVARD6 SUff E 350 diAMM-M NORTH CAROUNA 28217 PHONLi 704-426-6070 FAX- 704-426.6= www.to bertondbright.com �377- cn Z 0 C14 LONGITUDINAL VIEW -t I Lo N SECTION A-A B 0 NOT TO SCALE OVERFLOW WEIR BERM ELEV.=712' Lo 0 C14 ELEV.= 710.5! 5' 2 ENTRANCE WEIRS < W w CL N N 1293 t-- 1 w 1- n w 0 G1 z (D Fn w Z W w 0 w z fJ w __:> 0 w dot z 3�: < w 0 0 uJ = (n UJ a a_ CL a 0 6 OVERFLOW WEIR ELEV.= 710.5' (TYP� PONDING 2 12" ELEV.=710.5' 4" DIA * CLEAN —1 OUT PIPES 3 70�/ ELEV.= 709.5' /2," S D FILL MEDIA 85% SAND 10% FINES UNDERDRAIN PIPE TURN WITH 5% ORGANIC 3' FILL MEDIA r—GEO FILTER FABRIC PVC BENDS AS REQUIRE TOP BEND INV.=706.79 ELEV.= 706.,3,3--0%-_ 010% r-4" DIA. WASHED AND,; 0-5% MIN 8" NO. 57 ::4 12" A STONE 0.0% 5' 1 1 5'-" --1 o'--v- 4!' DIA. UNDERDRAIN —75 '_75' _75'— DISCHARGE PIPE I— - 300' B NOTES: 1. CONTRACTOR TO INSTALL STONE DITCH CHECKS, AS DIRECTED BY INSPECTOR, FOR EROSION CONTROL. 2. CONSTRUCT ALL DIVERSION DITCHES PRIOR TO INS_"?;LLATION OF BIORETENTION BASIN. 3. UNDERDRAIN PIPES TO BE SCHEDULE 40 PVC, ALL DRAIN PIPES EXCEPT DISCHARGE PIPE SHALL BE PERFORATED. DISCHARGE PIPE SHALL BE SOLID WALL. 4. CONTRACTOR TO BUILD BIORETENTION BASIN TO COMPLY GENERALLY WITH THE SHAPE ILLUSTRATED AND TO MAINTAIN 4.490 S.F. OF SURFACE AREA. 5. CONTRACTOR SHALL BE PROHIBITED FROM USING S00 THAT IS GROWN IN SOIL THAT HAS AN IMPERMEABLE LAYER (SUCH AS CLAY). SOD SHALL BE KENTUCKY 31 TALL FESCUE. LEGEND BIO-RETENTION BASIN EXISTING PAVEMENT PROPOSED CLEANOUT PROPOSED UNDERDRAIN SECTION B-B NOT TO SCALE TIE IN OVERFLOW WEIR El FV.=710.5" UhIDERDRAIN INV. ELEV.= 708.5' OUT El FV.=7049 I L 3' FILL MEDIA TIE IN I BERM ELEV.=71 4" DIA. CLEAN OUT PIPES WITH SCREW CAPS 1 893 8" STONE 5A \\-4" DIA. UNDERDRAIN PIPE 5'— 15' A—] \7--i 5' A--� EXISTING PIPE ------ ---EX: I NV_-OUT ::�- 7TG -INV OUT=711.5 PROP. 15 LF OVERFLOW WEIR :ue.-xi 7 0e, X _710— -7 -7 1 7'1 o. 5 EXISTING COT DITCH ......................... ""n —71 .0 . .. . ....... '710.5 '7 Al2- og ROW— ROW— ROW— ROW ROW—, ROW— ROW— ROW ROW— ROW,— ROW— ROW— ROW— F?nw—L OVERFLOW WEIR ELEV.= 710.5' , 2 � 1 20 10 0 20 40 61 SCALE IN FEET V$=2C LOT TIE IN TALBERT&BRIGHT ENGRGERING 6L PLANNING CONSULTANTS rj 4944 PAPJCWAY PLAZA BOULEVARD6 SUff E 350 diAMM-M NORTH CAROUNA 28217 PHONLi 704-426-6070 FAX- 704-426.6= www.to bertondbright.com �377- cn Z 0 ....... .. m C14 to I -t I Lo N 0 Lo 0 C14 < W w CL N N t-- 1 w 1- n w 0 G1 z (D Fn w Z W w 0 w z fJ w __:> 0 w dot z 3�: < w 0 0 uJ = (n UJ a a_ CL a 0 ....... .. m