Loading...
HomeMy WebLinkAboutSW8070817_HISTORICAL FILE_20160812STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO SW8 0_10 811 DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS HISTORICAL FILE ❑ COMPLIANCE EVALUATION INSPECTION DOC DATE 7-OW 08 12 YYYYMMDD w r I S '4 ,✓ Energy Mineral& Land Resources ENVIRONMENTAL QUALITY August 12, 2016 PAT McCRORY Governor DONALD R VAN DER VAART Secretary TRACY DAVIS Director Charles C Poindexter, II, Manger Robert Huth, Manager Pelican Point CB, LLC Developer HDI Holdings, LLC, Property Owner 7923 Reunion Rd 5929 Market St Wilmington, NC 28411 Wilmington, NC 28405-3615 Subject State Stormwater Management Permit No SW8 070817 Pelican Point High Dcusity Infiltration Trench Project New Hanover County Dear Mr Poindexter and Mr Huth The Wilmington Regional Office received a complete, modified State Stormwater Management Permit Application for Pelican Point on August 12, 2016 Staff review of the plans and specifications has determined that the project, as proposed will comply with the Stormwater Regulations set forth in Title 15A NCAC 2H 1000 We are forwarding modified Permit No SW8 070817 dated August 12, 2016, for the construction, operation and maintenance of the BMP s and built -upon area associated with the subject project This permit shall be effective from the date of issuance until October 12, 2021, and shall be subject to the conditions and limitations as specified therein Please pay special attention to the conditions listed in this permit regarding the Operation and Maintenance of the BMP(s), recordation of deed restrictions, certification of the BMP's, procedures for changing ownership, transferring the permit, and renewing the permit Failure to establish an adequate system for operation and maintenance of the stormwater management system, to record deed restrictions, to certify the BMP's to transfer the permit, or to renew the permit, will result in future compliance problems As the identified developer of the project, Pelican Point CB, LLC, shall be the designated permit holder and responsible for meeting the conditions and limitations specified therein The following modifications are included and covered by this permit 1 A revised site layout 2 The BMP has been re -designed and will be an infiltration trench Please be aware that it is the responsibility of the permit holders, Pelican Point CB, LLC and HDI Holdings, LLC, to notify the Division,of any changes in responsibility for complying with the permit and request an ownership/name change for the stormwater permit However, please be reminded that if the development agreement between Pelican Point CB, LLC and HDI Holdings, LLC is dissolved, cancelled or defaults, and the Division is not notified by Pelican Point CB, LLC to transfer the permit, then the responsibility for permit compliance reverts back to the property owner, HDI Holdings, LLC The Division must be notified immediately of any permit ownership changes and submit a completed Name/Ownership form to the Division within 30 days Otherwise Pelican Point CB, LLC and HDI Holdings, LLC will be operating a stormwater treatment facility without a valid permit This is a violation of NC General Statue 143-215 1 and may result in appropnate enforcement action including the assessment of civil penalties of up to $25,000 per day State of North Camlma I Environmental Quality I Energy himeral and Land Resources Wilmington Regional Office 1127 Cardinal Dave Extension I Wilmington NC 28405 910 796 7215 State Stormwater Permit No SW8 070817 Page 2 of 2 If any parts, requirements, or limitations contained in this permit are unacceptable, you have the right to request an adJudicatory hearing by filing a written petition with the Office of Administrative Hearings (OAH) The written petition must conform to Chapter 150B of the North Carolina General Statutes, and must be filed with the OAH within thirty (30) days of receipt of this permit You should contact the OAH with all questions regarding the filing fee (if a filing fee is required) and/or the details of the filing process at 6714 Mail Service Center, Raleigh, NC 27699-6714, or via telephone at 919-431-3000, or visit their website at www NCOAH com Unless such demands are made this permit shall be final and binding If you have any questions, or need additional information concerning this matter, please contact Christine Hall in the Wilmington Regional Office at (910) 796-7215 Sincerely 31" Tracy Dads, P E , DirectiSr Division of Energy, Mineral and Land Resources GDS/canh %Stormwater\Permits & Prolects\2007\070817 HD\2016 08 permit 070817 cc Jim Honeycutt, Jr PE New Hanover County Building Inspections New Hanover County Engineering Brian Stanberry, Town of Carolina Beach Division of Coastal Management Wilmington Regional Office Stormwater File State of North Carolina I Environmental Quality I Energy Mineral and Land Resources Wilmington Regional Office 1127 cardinal Drive Extension I wllnungton, NC 28405 910 796 7215 State Stormwater Management Systems Permit No SW8 070817 STATE OF NORTH CAROLINA DEPARTMENT OF ENVIRONMENTAL QUALITY DIVISION OF ENERGY, MINERAL AND LAND RESOURCES STATE STORMWATER MANAGEMENT PERMIT HIGH DENSITY DEVELOPMENT In accordance with the provisions of Article 21 of Chapter 143, General Statutes of North Carolina as amended, and other applicable Laws, Rules, and Regulations PERMISSION IS HEREBY GRANTED TO Pelican Point CB, LLC and HDI Holdings, LLC Pelican Point 402 N Lake Park Blvd, Carolina Beach, New Hanover County FOR THE construction, operation and maintenance of one (1) infiltration trench (hereafter referred to as infiltration system or stormwater control measure) in compliance with the provisions of 15A NCAC 2H 1000 (hereafter referred to as the "stormwater rules') and the approved stormwater management plans and specifications and other supporting data as attached and on file with and approved by the Division of Energy, Mineral and Land Resources (hereafter referred to as the Division or DEMLR) and considered a part of this permit This permit shall be effective from the date of issuance until October 12, 2021, and shall be subject to the following specified conditions and limitations I DESIGN STANDARDS This permit is effective only with respect to the nature and volume of stormwater described in the application and other supporting data This stormwater system has been approved for the management of stormwater runoff as described in Section 16 of this permit The runoff from all built -upon area within the permitted drainage area of this project must be directed into the permitted stormwater control measure The stormwater control has been designed to handle the runoff from 25,226 square feet of impervious area 3 The maximum built -upon area allowed for the entire project is 25,226 square feet The drainage area will be limited to the amount of built -upon area indicated in Sections 12 and 16 of this permit, and per approved plans This permit does not provide any allocation of built -upon area for future development The infiltration system is permitted per the Alternative Design Criteria under Section 1008 (h) The proposed system provides equal or better control, equal or better protection of surface waters and results in no increased potential for nuisance conditions The infiltration system can store at least 2 times the minimum design storm, therefore a LS/VFS is not required Page 1 of 7 State Stormwater Management Systems Permit No SW8 070817 The following design criteria have been permitted for the infiltration trench and it must be provided and maintained at the design condition Drainage Area 1 a Drainage Area acres Onsite ft' Offsite ft' 078 33,964 0 b Total Impervious Surfaces ft' Onsite, ft2 Offsite ft2 25 226 25,226 0 c Design Storm inches 1 0 d Trench Length feet 1,065 8 e Trench Width feet 4 5 and 7 66 f Trench Depth feet 1 25 Perforated Pipe Diameter in 6 h Perforated Pipe Length, ft 10658 i Bottom Elevation, FMSL 350 Bottom Surface Area, ft2 7 794 k Bypass Weir Elevation, FMSL 475 1 Permitted Storage Volume ft' 4,082 m Predevelopment 1 yr-24 hr discharge rate, cfs 0 04 n Type of Soil Sand o Expected Infiltration Rate, in/hr 625 1/2 of the measured rate Seasonal High Water Table FMSL 278 Time to Draw Down, hours 004 r Receiving Stream/River Basin Carolina Beach Yacht Basin / Cape Fear s Stream Index Number 18-87-31 2 t Classification of Water Body SIB II SCHEDULE OF COMPLIANCE 1 No person or entity, Including the permittee, shall alter any component of the approved stormwater system shown on the approved plans unless and until the Division has approved of the revised plan 2 The stormwater management system shall be constructed in Its entirety, vegetated and operational for Its Intended use prior to the construction of any built -upon surface 3 During construction, erosion shall be kept to a minimum and any eroded areas of the system will be repaired Immediately If the stormwater system is used as an Erosion Control device, it must be restored to design condition prior to operation as a stormwater treatment device, and prior to occupancy of the facility 4 The permittee shall at all times provide the operation and maintenance necessary to assure that all components of the permitted stormwater system function at design condition The approved Operation and Maintenance Agreement is incorporated by reference into this permit and must be followed in its entirety and maintenance must occur at the scheduled intervals Page 2 of 7 State Stormwater Management Systems Permit No SW8 070817 5 It is the responsibility of the permit holders, Pelican Point CB, LLC and HDI Holdings, LLC, to notify the Division of any changes in responsibility for complying with the permit and request an ownership/name change for the stormwater permit However, please be reminded that if the development agreement between Pelican Point CB, LLC and HDI Holdings, LLC is dissolved, cancelled or defaults, and the Division is not notified by Pelican Point CB, LLC to transfer the permit, then the responsibility for permit compliance reverts back to the property owner, HDI Holdings, LLC The Division must be notified immediately of any permit ownership changes and submit a completed Name/Ownership form to the Division within 30 days Otherwise Pelican Point CB, LLC and HDI Holdings, LLC will be operating a stormwater treatment facility without a valid permit This is a violation of NC General Statue 143-215 1 and may result in appropriate enforcement action including the assessment of civil penalties of up to $25,000 per day Records of maintenance activities must be kept and made available upon request to authorized personnel of the Division The records will indicate the date, activity, name of person performing the work and what actions were taken 6 The facilities shall be constructed in accordance with the conditions of this permit, the approved plans and specifications, and other supporting data 7 Upon completion of construction, prior to issuance of a Certificate of Occupancy, and prior to operation of this permitted facility, a certification must be received from an appropriate designer for the system installed certifying that the permitted facility has been installed in accordance with this permit, the approved plans and specifications, and other supporting documentation Any deviations from the approved plans and specifications must be noted on the Certification A modification may be required for those deviations All stormwater collection and treatment systems must be located in either public rights - of -way, dedicated common areas or recorded easements The final plats for the protect will be recorded showing all such rights -of -way, common areas and easements, in accordance with the approved plans Access to the stormwater facilities for inspection and maintenance shall be maintained via appropriate recorded easements at all times The permittee shall submit to the Director and shall have received approval for revised plans, specifications, and calculations prior to construction, for any modification to the approved plans, including, but not limited to, those listed below a Any revision to any item shown on the approved plans, including the stormwater management measures, built -upon area, details, etc b Redesign or addition to the approved amount of built -upon area or to the drainage area c Further development, subdivision, acquisition, lease or sale of any, all or part of the protect area The project area is defined as all property owned by the permittee, for which Sedimentation and Erosion Control Plan approval or a CAMA Major permit was sought d Filling in, altering, or piping of any vegetative conveyance shown on the approved plan e The construction of any future BUA listed on the application 10 Prior to transfer of the permit, the stormwater facilities will be inspected by Division personnel The project and the stormwater facility must be in substantial compliance with all permit conditions Any items not in substantial compliance must be repaired, replaced or restored to design condition prior to the transfer Records of maintenance activities performed to date will be required Page 3 of 7 State Stormwater Management Systems Permit No SW8 070817 11 The Director may notify the permittee when the permitted site does not meet one or more of the minimum requirements of the permit Within the time frame specified in the notice, the permittee shall submit a written time schedule to the Director for modifying the site to meet minimum requirements The permittee shall provide copies of revised plans and certification in writing to the Director that the changes have been made III GENERAL CONDITIONS 1 Any individual or entity found to be in noncompliance with the provisions of a stormwater management permit or the stormwater rules, is subject to enforcement action as set forth in NCGS 143, Article 21 2 The issuance of this permit does not preclude the Permittee from complying with any and all statutes, rules, regulations, or ordinances, which may be imposed by other government agencies (local, state, and federal) having jurisdiction 3 In the event that the facilities fail to perform satisfactorily the Permittee shall take immediate corrective action, including those as may be required by this Division, such as the construction of additional or replacement stormwater management systems Additional or replacement stormwater management systems shall receive a permit from the Division prior to construction 4 This permit is not transferable to any person or entity except after notice to and approval by the Director The permittee shall submit a completed and signed Name/Ownership Change Form, accompanied by the supporting documentation as listed on the form, to the Division of Energy, Mineral and Land Resources at least 60 days prior to any one or more of the following events a An ownership change including the sale or conveyance of the project area in whole or in part, except in the case of an individual lot sale that is made subject to the recorded deed restrictions, b The sale or conveyance of the common areas to a Homeowner's or Property Owner's Association, subject to the requirements of Session Law 2011-256, c Bankruptcy, d Foreclosure, subject to the requirements of Session Law 2013-121, e Dissolution of the partnership or corporate entity, subject to NCGS 57D-2-01(e) and NCGS 57D-6-07, f A name change of the current permittee, g A name change of the project, h A mailing address change of the permittee, 5 The permittee is responsible for compliance with all permit conditions until such time as the Division approves the transfer request Neither the sale of the project, in whole or in part, nor the conveyance of common area to a third party constitutes an approved transfer of the stormwater permit 6 The permittee grants DEMLR Staff permission to enter the property during normal business hours for the purpose of inspecting all components of the permitted stormwater management facility 7 The permit issued shall continue in force and effect until modified, revoked, terminated or renewed The permit may be modified, revoked and reissued or terminated for cause The filing of a request for a permit modification, revocation and re -issuance or termination does not stay any permit condition 8 Approved plans, calculations, supplement forms, operation and maintenance agreements and specifications for this project are incorporated by reference and are enforceable parts of the permit A copy of the approved plans and specifications shall be maintained on file by the Permittee at all times Page 4 of 7 State Stormwater Management Systems Permit No SW8 070817 9 Unless specified elsewhere, permanent seeding requirements for the stormwater controls must follow the guidelines established in the North Carolina Erosion and Sediment Control Planning and Design Manual 10 The issuance of this permit does not prohibit the Director from reopening and modifying the permit, revoking and reissuing the permit, or terminating the permit as allowed by the laws, rules and regulations contained in Session Law 2008-211, Title 15A NCAC 2H 1000, and NCGS 143-215 1 et al 11 The permittee shall submit a permit renewal application request at least 180 days prior to the expiration date of this permit The renewal request must include the appropriate application, documentation and the processing fee Permit modified and reissued this the 12th day of August 2016 NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION Division of Energy, Mineral and Land Resources By Authority of the Environmental Management Commission 11--TN iI i►[Ri1:1 �9h'E:IrfLrYlrtl Page 5 of 7 State Stormwater Management Systems Permit No SW8 070817 Pelican Point Stormwater Permit No SW8 070817 New Hanover County Designer's Certification I, , as a duly registered in the State of North Carolina, having been authorized to observe (periodically/ weekly/ full time) the construction of the project, (Project) for (Project Owner) hereby state that, to the best of my abilities, due care and diligence was used in the observation of the project construction such that the construction was observed to be built within substantial compliance and intent of the approved plans and specifications The checklist of items on page 2 of this form is included in the Certification Noted deviations from approved plans and specification Signature Registration Number Date SEAL Page 6 of 7 State Stormwater Management Systems Permit No SW8 070817 Certification Requirements .1 The drainage area to the system contains approximately the permitted acreage 2 The drainage area to the system contains no more than the permitted amount of built -upon area 3 All the built -upon area associated with the project is graded such that the runoff drains to the system 4 All roof drains are located such that the runoff is directed into the system 5 The bypass structure weir elevation is per the approved plan 6 The bypass structure is located per the approved plans 7 A Trash Rack is provided on the bypass structure 8 All slopes are grassed with permanent vegetation 9 Vegetated slopes are no steeper than 3 1 10 The inlets are located per the approved plans and do not cause short-circuiting of the system 11 The permitted amounts of surface area and/or volume have been provided 12 All required design depths are provided 13 All required parts of the system are provided 14 The required system dimensions are provided per the approved plans cc NCDEQ-DEMLR Wilmington Regional Office New Hanover County Building Inspections Page 7 of 7 Hall, Christine From Hall, Christine Sent Thursday August 11, 2016 4 15 PM To Charles Poindexter, Engineer Jim Honeycutt (mason boro@bellsouth net) Cc Weaver, Cameron Subject RE Charles P Checking In Charles / Jim, I have had the opportunity to take a look at the additional items received on August 2"' In looking at these items, I found two minor things that need to be addressed 1 The revised infiltration trench supplement lists the infiltration rate as "m" This appears to be a typo as this rate was completed on the original supplement Can I get a revised version with the infiltration rate listed? 2 1 also need two sets of plans per 15A NCAC 02H 1003(g)(1) However, only one set of the revised drainage plan was provided Can I please get a second copy? I'm hoping these two items can be taken care of easily enough that I don't need to write another letter As always, please let me know if you have any questions or concerns Thank you again for your patience' Christine Christine Hall Environmental Engineer Division of Energy, Mineral and Land Resources — State Stormwater Program Department of Environmental Quality 910 796 7215 office 910 796 7335 direct chnstine hall@ncdenr gov 127 Cardinal Drive Ext Wilmington, NC 28405 := Nothing Compares� Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed to third parties From Charles Poindexter [mailto ccpii@mac com] Sent Thursday, August 11, 2016 8 37 AM To Hall, Christine <Christine Hall@ncdenr gov> Subject Re Charles P Checking In No problem, thank you Christine Hope you are feeling better With kind regards, Charles C Poindexter, II 910 620 4672 ccpunmac coin On Aug 11, 2016, at 8 18 AM Hall, Christine <Christine I lall a ncdenr sov> wrote Charles, I did receive the information but have not had the opportunity yet to review it I have been battling a very nasty cold and am trying to catch up from a few days off I hope that I can look at it today 1 hank you for your patience? Christine Christine Hall Environmental Engineer Division of Energy, Mineral and Land Resources - State Stormwater Program Department of Environmental Quality 910 796 7215 office 910 796 7335 direct christme hallna nedenr gov 127 Cardinal Drive Ext Wilmington, NC 28405 Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed to third parties -----Original Message----- FromCharles Poindexter [mailto can a,mac coin] Sent Thursday, August 11, 2016 8 10 AM To Hall, Christine <Christine Hall a,ncdenr gov> Subject Charles P Checking In Good morning Christine Just checking in to see how everything is going with our permit I hanks for your time, I hope we are good to go With kind regards, Charles C Poindexter, II Page 1 of 1 From Jim Honeycutt <masonboro(a),bellsouth net> Date August 1, 2016 at 8 20 22 PM EDT To Charles Poindexter <ccmrnn mac com> Subject Pelican Point CNi> TyrrrVJ >The drainage area listed in the calculations, the application, and the supplement has been corrected he calculations for the storage volume required is shown on page 2 (about midpage) of the calculations The trench width will be 7'8" in most places The trenches in the pool area will be 4'6" This has been clarified on drawing C3 he width of the trench that was projecting into the 30' setback was changed to 4'6" in order to keep it out of the setback All trenches are now outside the 30' setback Soil boring 3 is now shown on the drawing along with existing and proposed elevations and the SHWT elevation The elevation of the SHWT has been changed on the supplement to 3 5 he elevation of the bottom of the trench will be 3 5 The elevation of the SHWT at its highest point is 2 78 The detail on sheet C3 has been corrected -->The monitoring well in question has been moved 3 The option for eliminating the vegetated buffer by doubling the required storage volume and using one half the infiltration rate was used The narrative has been updated to reflect this 4 An existing note to tie gutters to the pipes in trench 1 & 2 was moved and enlarged so as to be more visible 5 Infiltration trench 0&M agreement attached 6 N/A 7 N/A Call if you have any questions / Jim Honeycutt 910-512 0729 RECEIVE'D� S 8/2/2016 AUG 0 2 2016 Life` S I ID ! [ �• 9 �I Za � �ti�VeanZ-�.�• 4amw�. ou+r��amq igYrYrsescvxR�rlY�ai+s`nay��tmc,.rw iQl �i�'.t3+�rlvY"lY 4swi �Vi �l'rr ayws�ti �.gO1r����.+rYf.� C1`�xAKt.'t �T� sin�a��ry- �..:ftHffRl= MDI� i:-+^Jr6.�<S��se'v�6� ia]�`91cb *a'�.xt��n^aa..�e eu�. anvay NARRATIVE ON PELICAN POINT 402 N LAKE PARK BLVD CAROLINA BEACH, NORTH CAROLINA AU STORMWATER MANAGEMENT PLAN ey??415 A stormwater permit (SW8 070817) was issued for this site in 2007 However, the site was never developed Since that time the owner of the property has changed The new owner has developed a different plan for the site The purpose of this application is to modify that original permit to accommodate development of the site per the new plan It is planned to collect and treat stormwater in an infiltration system under the same rules in effect in 2007 The site located at 402 Lake Park Blvd is approximately 985 acres (42,893 square feet) with 3942 square feet below the mean high water line 8429 square feet of the site are in the AEC The project will consist of a four story building with 36 units on piles with associated parking The project has a small swimming pool adjacent to the AEC The site has one drainage basin with an area of 0 78 acres Approximately 0 11 acres of pervious area will drain offsite after development Runoff from the roof will be routed directly into infiltration trenches on each side of the building Runoff from the remainder of the site will be routed via surface grading to catch basins and then into a series of smart boxes The smart boxes have an internal weir that directs the water into the infiltration system trenches All trenches are interconnected Overflow from one smart box drains to the next smart box and so on The elevation of the seasonal high water table (SHWT) varies from elevation 1 99 at boring B-2, 2 41 at B-3, and 3 69 at boring B-1 Infiltration rates vary on the site from 12 5 to 18 5 inches per hour Since no vegetative filter is provided, the infiltration system was designed with a storage volume twice the required storage volume for the first 1" of runoff in the drainage basin The infiltration rate used in the design was one half of the lowest infiltration rate from the soil reports The system has also been designed to pass the 10 year and 50 year storms with a non - erosive velocity The site contains coastal wetlands of which about 100 square feet will be affected by the pipe discharging from the site A major CAMA permit for the site has been approved with conditions Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 1 Protect 15023 7/5/16 - Revised 7/30/16 Atotal = 38879 Atotal = 0 893 acres total site area above mean high water line before development 43560 33964 Abmp 43560 Abmp = 0 78 acres total area draining to infiltration system Agave = 14458Agave = 0 332 Paved areas 43560 910 Amisc = 43560 ta•misc = 0 021 acres Abldg = 9858 Abldg = 0 226 acres bldg area 43560 Aimp = Apave + Amrec + Abldg A,,,,p = 0 579 acres total impervious area 4822 Aoffsite = Aoffsde = 0 111 acres pervious area draining offsite 43560 Aother = / Abmp — Aimp — (Aoffsde) Aother = 0 09 pervious area draining to infiltration system Cp,e = 30 pre -development C C,mp = 95 paved area C Cbldg = 0 90 building C Aother (Apave + Amisc Abldg Ccomp = Cpfe + Ctmp + Cbldg )I Abmp Abmp Abmp Camp = 0 726 composite C (post -development) la L = 320 ft hydraulic length H = 8 ft height �Qy�B�� 385 pt;G 9 2 NIB L3 H TO = 128 Tc = 2 75 minutes time of concentration BY ��— T = if(Tc < 5, 5,Tc� T = 5 minutes Time of duration (use 5 minutes min.) Intensity -Duration -frequency Relationships Values of G and H` R G H 2 182 26 10 268 32 25 326 35 50 364 36 100 403 37 R= Return Period Source New Hanover County Stormwater manual G2 stet to Q°rlE° /C 2d•'Q� �'�s �R'CiNB�P.•�,t.w 'eretttu ltl %t t4 G2 = 182 Hz = 26 12 = 12 = 5 87 in/hr 2 year storm intensity (H2 + T) Gto = 268 Hto = 32 Ito = /H + T G1 Ito = 7 24 in/hr 10 year storm intensity to / Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 2 G25 = 326 H25 = 35 G25 / 125 = \H25 + T) G50 G50 = 403 H50 = 37 150 = /H50 + T1 Compute runoff rates Q10pre = Cpre 110 (Abmp) Q10pre = 1 69 cfs Q10 — Ccomp 110 Abmp/ Q10 = 4 1 cfs Q50 = Ccomp 150 (Abmp) Q50 = 5 43 cfs 125 = 8 15 in/hr 25 year stone intensity 150 = 9 595 m/hr 50 year storm total pre -development runoff from 10 yr storm post -development discharge rate from 10 yr storm post -development discharge rate from 50 yr storm Volume of runoff from developed area of site IA = Aimp IA = 0 743 Abmp Rv=005+091A Rv=0718 RD = 1 0 in runoff depth Volumerequved = 3630 Rp Rv Abmp Volumereginred = 2033 P1 = 2 79 P2 = 3 38 in P10 = 5 18 in P25 = 6 45 in P50 = 7 57 P100 = 8 84 in Soil type = Fine to medium sand Apave Abldg Aother CN = — 98 + 98 + 39 Abmp Abmp Abmp 1000 S = CN -10 S=3394 (P1 - 0 2 S)2 Rldepth = + 8 S Rldeptn = 0 81 n P 1 R1voj = Rldepth (Abmp) 43560 112 R1vo1=2291 Rldepth (Abmp) 1 t T1p = 1 39 (Q10) (12) 43560 60 VG'VE AUG 0 11111 BY CN = 75 runoff depth cubic feet Curve No runoff volume to infiltration system Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 3 T1p = 6 7 minutes time to peak flow T1p OT1 = OT1 = 0 67 time increment for routing 1 year storm 10 Now compute runoff depth and time to peak for 10 yr storm �Pto-02 S)2 R10depth = + 8 S R1 Odepth = 2 566 in runoff depth Pto R10vdj = R10depth (Abmp) 43560 112 R1Ovpi = 7263 cubic feet R10depth (Abmp) 1 1 T10p = 1 39 (Qto ) (12) 43560 60 T10p = 21 25 minutes time to peak flow T10p OT10 = — AT10 = 2 125 time increment for routing 10 year storm 10 Now compute runoff depth and time to peak for 50 yr storm �Pso-02 S12 R50depth = R50depth = 4 617 in runoff depth Pso + 8 S1 R50voi = R50depth (Abmp) 43560 112 R50vol = 13068 cubic feet T50 _ R50depth (Abmp) 1 43560 1 p 1 39 (Qso) (12) 60 T50p = 28 86 minutes time to peak flow T50p AT50 = — AT50 = 2 886 time increment for routing 50 year storm 10 Develop stage -storage function m= 0 6 n= 1 6 contouro = 3 5 increment = 5 ft 12 trenchlength2 = 946 69 length of trench 7 66 ft wide width2 = 7 + 8 ft 12 runoff volume to infiltration system runoff volume to infiltration system trenchlengthl = 119 1 length of trench 4 5 ft wide widthl = 4 5 ft trenchlength = trenchlengthl + trenchlength2 trenchlength = 1065 79 bottom areal = trenchlengthl widthl bottom areal = 535 95 sq ft bottom_area2 = trenchlength2 width2 bottom_area2 = 7 258 x 103 sq ft Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 4 contourn = contourn_1 + increment am = bottom_area1 + bottom_area2 contourm = contours of proposed trench am = area of contours of proposed trench 35 7794 3 708 7794 3 917 7794 4 125 7794 4 333 7794 4 542 7794 4 75 7794 yr = 0 419 assumed void ratio of stone ( 4) + pipe volume an-1 + an vn = 2 (contourn - contourn_1) yr incremental volume (cubic ft ) vm = SO = 0 initial storage Sri = Sn_1 + vn cumulative storage (cubic ft ) Sm = 0 680 1361 2041 2721 3402 4082 0 6803 6803 680 3 6803 680 3 680 3 Volumerequired = 2 033 x 103 Volume provided S6 = 4082 InZn = In(stagen) InZn = -1 5686 -0 8755 -0 47 -0 1823 00408 02231 x = submatrix(InZ, 2, 5, 0, 0) must be equal to or greater than InSn = In(Sn) InSn = 65226 72157 76212 79089 8 132 83144 stagen = contourn - contour0 stagen = 0208 0 417 0 625 0 833 1 042 1 25 2 Volumerequired = 4067 OK Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina y = submatrix(InS, 2, 5, 0, 0) slope=slope(x,y) slope =1 b = intercept(x , y) b = 8 09 1 - / KS = eb KS = 3 266 x 103 S II` m slope Zestm KS Should compare closely with Zestm = stagem = 0 0 0208 0208 0 417 0 417 0 625 0 625 0 833 0 833 1 042 1 042 1 25 1 25 Size emergency spillway to pass 50 year peak flow Cw = 3 0 weir coefficient Hew = 37 driving head over emergency weir (ft ) Qs0 Lw = 5 Cw Hew Lw = 2 98 ft (minimum) Lw = 3 ft length chosen Ecr = 4 75 crest elev of overflow weir u = 0 25 v = 1 25 Continue with routing calcs Since infiltration rates from 12 5 to 18 5 inches per hour can be expected, use an average of 112 lower rate 125 — in K = 2 K = 1 447 x 10 4 cfs unit infiltration rate hr ft2 Route 10 year storm OT10 AT = 1 5 Q = Q10 Q = 4 098 TP = T10P set variables for storm to be routed iter = 70 number of iterations u = 0 der m = 0 5 Check mass balance of matrix calcs Storage = Miter.2 Storage = 823 Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 0 iter Inflowtotal = Y, T(Mv,1) (Mv,0 - My-1,0) 601 Inflowtotal = 7250 cubic feet v = 1 iter Outflowtotal = Y T(Mv,4 + Mv,5) (Mv 0 - My-1,0) 601 Outflowtotal = 6426 cubic feet v = 1 Inflowtotal - Outflowtotal = 823 MUST BE REASONABLY CLOSE TO Storage = 823 O K iter Infiltration = I T(Mv,4) (Mv,0-My-1,0) 60� Infiltration = 6426 cubic feet v = 1 der Outflowv,,er = E T(Mv,5) (Mv,0 - My-1,0) 601 OutflowW1ef = 0 cubic feet v = 1 Display a portion of routing results timeu = Mu 0 inflowu = Mu 1 storageu = Mu 2 stageu = Mu 3 + contour0 infiltrationu = Mu 4 weiru = Mu 5 maxelevation = max(stage) maxelevation = 4 56 maxdischarge = max(weir) maxdischarge = 0 (See next page for routing results) Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina minutes cfs cubic feet ft cfs cfs timeu = inflowu = storageu = stageu = infiltrationu = weiru = Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina CHAINSAW ROUTING FOR 10 YR STORM 5 4 3 2 1 - - - - - - - - - - - - - - - - - - - - - 0 0 20 40 60 80 11 TIME (minutes) INFLOW — — INFILTRATION — — WEIR Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 0 Route 50 year storm OT50 AT = z Q = Q50 Q = 5 429 set variables for storm to be routed TP = T50P der = 70 number of iterations Check mass balance of matrix calcs Storage = Miter,2 Storage = 3272 der Inflowtotal = I LL(Mv 1) (Mv 0 - My-1 0) 601 v=1 der Outflowtotal = Y T(Mv, 4+Mv,5) (Mv,0-My-1,0) 60T v = 1 Inflowtotal = 12793 u= 0 iter m= 0 5 cubic feet Outflowtotal = 9520 cubic feet Inflowtotal - Outflowtotal = 3272 MUST BE REASONABLY CLOSE TO Storage = 3272 O K der Infiltration = I T(Mv,4) (Mv,0 - Mv_1,0) 60T Infiltration = 6499 cubic feet v=1 iter Outflow,,er = Y' T(Mv, 5) (Mv, 0 - My-1 0) 601 OutflowW1ef = 3022 cubic feet v = 1 Display a portion of routing results time, = Mu,0 mflowu = Mu 1 storage, = Mu,2 stageu = Mu 3 + contour0 mfdtrationu = Mu 4 weiru = Mu 5 maxelevatlon = max(stage) maxelevatlon = 5 12 maxdlscharge = max(weir) maxdlscharge = 1 988 (See next page for routing results) Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 10 minutes timeu = cfs inflowu = 0 003 0 13 03 052 08 1 12 148 188 229 271 314 355 395 431 463 491 5 13 53 54 543 54 53 5 13 491 463 435 407 382 358 335 3 14 294 276 2 58 2 42 2 27 cubic feet storageu = ft stageu = 35 35 35 35 35 35 35 351 353 356 36 366 372 379 388 397 407 418 429 44 452 463 474 484 492 499 504 507 509 5 11 5 11 5 12 5 11 51 5 09 5 08 507 cfs cfs infiltration, = Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 11 LL U CHAINSAW ROUTING FOR 50 YR STORM I / I \ I \ I \ I \ I \ I \ — INFLOW — — INFILTRATION — — WEIR 50 inn TIME (minutes) Drainage Calculations for Pelican Point 402 N Lake Park Blvd Carolina 12 Check drawdown time S6 ft3 drawdown = K a1 ft2 drawdown = 1 006 hr Size pipe and outlet structure n = 012 (Q50 n)0375 D = 16 s 5 rD12 in A J 2 s = 006 D = 14 994 in A = 1 227 P=TrD P=3927 A R =? R=0313 use 12 in min D = 1 25 ft diameter of pipe so ft Cross sectional area of flow when flowing full ft when flowing full Hydraulic radius when flowing full Voutlet = l 11 491J �R�0 67 50 5 Voutlet = 4 412 fps n From Figure 8 06 b 1 and Figure 8 06 b 2 choose Zone 1 La = 3 D La = 3 75 ft - minimum length of apron from figure 8 06b2 W = 4 D W = 5 ft - minimum width of apron from figure 8 06b2 diam = 3 diameter of stone in inches dmax = 1 5 diam dmax = 4 5 max stone diameter t = 12 in min thickness of apron in inches Hall, Christine From Hall, Christine Sent Friday, July 29, 2016 104 PM To Jim Honeycutt Cc Charles Poindexter Subject RE Pelican Point Stormwater Project No SW8 070817 Jim, An extension until August 3rd is fine with me Thank you for the email) Christine Christine Hall Environmental Engineer Division of Energy, Mineral and Land Resources — State Stormwater Program Department of Environmental Quality 910 796 7215 office 910 796 7335 direct chnstine hall@ncdenr gov 127 Cardinal Drive Ext Wilmington, NC 28405 �Nothmg Compares Email correspondence to and from this address Is subject to the North Carolina Public Records Law and may be disclosed to third parties From Jim Honeycutt [mailto masonboro@bellsouth net] Sent Friday, July 29, 2016 12 29 PM To Hall, Christine <Christine Hall@ncdenr gov> Cc Charles Poindexter <ccp❑@mac com> Subject Pelican Point - Stormwater Project No SW8 070817 The purpose of this email is to request an extension to the required submittal date for additional info from August 1, 2016 to August 3, 2016 Please let me know that you have received this Thanks, Jim Honeycutt 910-512-0729 k. Hall, Christine From Hall, Christine Sent Tuesday, July 26, 2016 107 PM To Jim Honeycutt Cc Charles Poindexter Subject RE Pelican Point - Stormwater Project No SW8 070817 Jim, Thanks for the e-mail This calculation is missing from the set that was submitted In looking at the calculation on your attachment, it looks like you only considered the impervious area draining to the system You also need to consider the pervious area as well Granted, it won't contribute the complete 1" of rainfall runoff, but it still will contribute a fraction of it The required volume will need the consider the entire drainage area, both pervious and impervious areas Also, in looking at this new calculation, the required volume is low based on the site design I looked back at your calculations and it looks like the areas listed on page 1 are not quite adding up For instance, the total impervious area lust includes the pavement and the miscellaneous areas Why is the building area not included? Also the sum of the paved areas, miscellaneous areas, building area, and other pervious areas do not appear to add up to the total drainage area Please let me know if you have any other questions Christine Christine Hall Environmental Engineer Division of Energy Mineral and Land Resources - State Stormwater Program Department of Environmental Quality 910 796 7215 office 910 796 7335 direct christine hall@ncdenr gov 127 Cardinal Drive Ext Wilmington NC 28405 -:5-"Nothing Compares Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed to third parties From Jim Honeycutt [mailto masonboro@bellsouth net] Sent Monday, July 25, 2016 3 18 PM To Hall, Christine <Chnstine Hall@ncdenr gov> Cc Charles Poindexter <ccpii@mac com> Subject Pelican Point - Stormwater Project No SW8 070817 This email is in reference to item 1 b on your request for more information I've attached a copy of page 3 of the calculations with what I think is the calculation you are requesting circled Could you verify that this is the calculation you are requesting and, if not, help me understand what it is you need? Energy Mineral & Land Resources ENVIRONMENTAL QUALITY July 22, 2016 Charles C Poindexter, II, Manger Pelican Point CB, LLC, Developer 7923 Reunion Rd Wilmington, NC 28411 Subject Request for Additional Information Stormwater Project No SW8 070817 Pelican Point New Hanover County Dear Mr Poindexter and Mr Huth PAT McCRORY Governor DONALD R VAN DER VAART Secretary TRACY DAVIS Director Robert Huth, Manager HDI Holdings, LLC, Property Owner 5929 Market St Wilmington, NC 28405-3615 The Wilmington Regional Office received and accepted a modified Express State Stormwater Management Permit Application for Pelican Point on July 15, 2016 A preliminary in-depth review of that information has determined that the application is not complete The following information is needed to continue the stormwater review 15A NCAC 02H 1003(g)(7) Provide technical information showing final numbers, calculations, assumptions, drawings and procedures associated with the stormwater management measures including The drainage area listed in the calculations (38,893 ft') is different than the area listed in the application and supplement (38788 ft') Please confirm the drainage area of the infiltration trench is presented consistently among the application documents ✓b' As discussed in the submittal meeting, please provide the calculations demonstrating the minimum required volume or provide a citation of where this calculation can be found the revised calculations submitted on July 1 Ith and accepted on July 15th do not appear Xto contain this information The infiltration trench supplement and plans indicate that the width of the infiltration trench will be 5 ft However, the detail on C3 indicates the width will be 4 feet Please confirm the width of the infiltration trench 15A NCAC 02H 1008(d) /a— Under the 1995 Rules, infiltration systems must be a minimum of 30 feet from non -SA surface waters According to sheet C3, a very small portion of the infiltration trench appears to be within the 30 feet setback from the mean high water line Please confirm b h S~ that the infiltration trench is located outside of the 30-foot setback , :;O9i"!'� Please provide the existing ground elevation in the vicinity of solCboring�3't3 support t,41 " �6 the identified seasonal high water table (SHWT) elevations Additionally, —please identify 1 �� ,tlie highest elevation of the SHWT on the supplement to document the limiting elevation for the design of the infiltration system (refer to Item 2 c of this letter) tic According to the supplement and the detail on sheet C3, the bottom elevation of the trench is proposed to be 3 25 It However, the profile from boring B-I to smart box 4 appears to indicate that the bottom of the trench will be at an elevation of 3 5 ft, which appears to approximately be at the 6-inch minimum required separation from the SHWT near Smart Box I Please confirm the elevation of the trench bottom and ensure that it provides at least a 6-mch separation from the SHWT u/d The plans indicate a monitoring well will be located west of the proposed infiltration trench Please re -locate this monitoring well to within the vicinity of french 3 or the western parts of french 1 or 2 State of North Carolina I Environmental Quality I Energy Mineral and Land Resources Wilmington Regional Office 1 127 Cardinal Drive Extension I Wilmington NC 28405 910 796 7215 State Stormwater Permit No SW8 070817 Page 2 of 2 /I5A NCAC 02H 1008(c)(4) and 1008(h) I he overflow from an infiltration system must be directed to a vegetated filter strip During the submittal meeting, options to eliminate this requirement for a vegetated filter strip In accordance with Section 16 3 9 of the NC BMP Manual were discussed Without the calculation demonstrating how the minimum required storage volume of 2,562 ft' was determined (refer to item 1 b of this letter), it is not clear which alternative design option is being utill7ed to waive the requirement for a vegetated filter strip If one of the alternative designs presented in Section 16 3 9 of the NC BMP manual is being utilized, please provide the calculations demonstrating how the infiltration system meets the alternative design and update the narrative to discuss which alternative design was selected ✓4 15A NCAC 021-1 1005(a)(3)(13)(m) Please either demonstrate how the roof runoff will be directed to the stormwater collection and/or treatment system or include a note on the plans to direct the roof runoff to the stormwatcr collection system V15A NCAC 0214 1003(g)(8) I he proposed stormwater treatment system is an infiltration trench, however, the provided operation and maintenance (O&M) agreement is for an infiltration basin Please provide the operation and maintenance agreement appropriate for the proposed stormwater treatment system 6 Due to the relatively minor nature of these comments, the express additional information review fee has been waived 7 Please keep in mind that changing one number may change other numbers and require the calculations, supplements, and other supporting dowmentation to be updated Verify all numbers are correct to ensure consistency in the application documents Please note that this request for additional information is in response to a preliminary review The requested information should be received in this Office prior to August 1, 2016, or the application will be returned as incomplete If the project is returned and you wish to re -submit to the Express Program, you will need to reschedule the project through the Express Coordinator for the next available review date and will need to resubmit all of the required items at that time, including the application fee If you need additional time to submit the information, please email or fax your request for a time extension to the Division at the email address or fax number at the bottom of this letter 7 he request must Indicate the date by which you expect to submit the required information, which shall be no later than 5 business days past the original due date The construction of any impervious surfaces other than a construction entrance under an approved Sedimentation Erosion Control Plan, is a violation ofNCGS 143-215 1 and is subject to enforcement action pursuant to NCGS 143-215 6A Please label all packages and cover letters as "Express' and reference the project name and State assigned project number on all correspondence If you have any questions concerning this matter, please feel free to call me at (910) 796-7215 or email me at christine hall@ncdenr gov Sincerely,// / C1J- 4 /l G.&/n Christine Hall Environmental Engineer GDS/canh \\\Stormwater\Permits & Projects\2007\070817 HD\2016 07 addmfo 070817 cc James Honeycutt, Jr, PE Wilmington Regional Office Stormwater File State of North Carolina I En"ronmental Quality I Energy Mineral and Land Resources Wilmington Regional Office 1127 Cardinal Drive Extension I Wilmni NC 28405 910 796 7215 Hall, Christine From Hall, Christine Sent Friday, July 22, 2016 12 45 PM To Charles Poindexter, Engineer Jim Honeycutt (masonboro@bellsouth net) Cc Weaver, Cameron Subject request for additional info - Pelican Point, SW8 070817 Attachments 2016 07 addinfo 070817 pdf Gentlemen, Attached is a pdf of the request for additional information for the modification to Pelican Point, SW8 070817 Please let me know if you have any questions or concerns Thanks, Christine Christine Hall Environmental Engineer Division of Energy, Mineral and Land Resources - State Stormwater Program Department of Environmental Quality 910 796 7215 office 910 796 7335 direct chnshne hall@ncdenr gov 127 Cardinal Drive Ext Wilmington, NC 28405 -�'--^Nothmg Compares.,. Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed to third parties Hall, Christine From Hall Christine Sent Wednesday, July 20, 2016 2 23 PM To Charles Poindexter Subject RE Charles P - CORRECTED App page 3 Thanks The transfer has been approved and the modification is next up in line of projects I need to review I have one on my desk I need to finish up first but hopefully I can get started looking at it tomorrow Christine Hall Environmental Engineer Division of Energy Mineral and Land Resources — State Stormwater Program Department of Environmental Quality 910 796 7215 office 910 796 7335 direct christine hall@ncdenr gov 127 Cardinal Drive Ext Wilmington, NC 28405 10- -^/'Nothing ComparesN_ Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed to third parties From Charles Poindexter [mailto ccp❑@mac com] Sent Wednesday, July 20, 2016 122 PM To Hall, Christine <Christine Hall@ncdenr gov> Subject Charles P - CORRECTED App page 3 Hey Christine Here is the corrected applicant section for Pelican Point CB, LLC IIow are we looking on time do you think? No rush, just curious 1