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HomeMy WebLinkAboutSW8951105_Historical File_19960229State of North Carolina Department of Environment, 4 � . Health and Natural Resources Division of Environmental Management James B. Hunt, Jr., Governor C) FE F1 Jonathan B. Howes, Secretary A. Preston Howard, Jr., P.E., Director February 29, 1996 Mr. W. Keith Elmore, President Lyndale Enterprises, Inc. 3808 Oleander Drive Wilmington, North Carolina 28403 Subject: Permit No. SW8 951105 Lot 31-Landmark Industrial Park High Density Stormwater Project New Hanover County Dear Mr. Elmore: The Wilmington Regional Office received the Stormwater Application for Lot 31-Landmark Industrial Park on November 3, 1995, with final information on February 8, 1996. 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 Permit No. SW8 951105 dated February 29, 1996, to Lyndale Enterprises, Inc.. This permit shall be effective from the date of issuance until February 28, 2006, and shall be subject to the conditions and limitations as specified therein. Please pay special attention to the Operation and Maintenance requirements in this permit. Failure to establish an adequate system for operation and maintenance of the stormwater management system will result in future compliance problems. If any parts, requirements, or limitations contained in this permit are unacceptable, you have the right to request an ajudicatory hearing upon written request within thirty (30) days following receipt of this permit. This request must be in the form of a written petition, conforming to Chapter 150B of the Nor. itb Carolina General Statutes, and Bled with the Office of Administrative Hearings, P.O. Drawer 27447, Raleigh, NC 27611-7447. 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 Linda Lewis, or me at (910) 395-3900. Sincerely, Dave Adkins Regional Water Quality Supervisor DA/arl: S:1WQSISTORMWATIPERMIT1951105.FEB cc: Jim Honeycutt, P.E. Beth Easley, New Hanover County Soil Erosion Alan Golden, New Hanover County Inspections David Mayes, P.E., City of Wilmington Linda Lewis Wilmington Regional Office, Central Files P.O. Box 29535, Raleigh, North Carolina 27626-0535 Telephone 919-733-5083 FAX 919-733-9919 An Equal Opportunity Affirmative Action Employer State Stormwater Management Systems Permit No. SW8 951105 STATE OF NORTH CAROLINA DEPARTMENT OF ENVIRONMENT, HEALTH AND NATURAL RESOURCES DIVISION OF ENVIRONMENTAL MANAGEMENT STATE STORMWATER MANAGEMENT PERNIIT 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 Lyndale Enterprises, Inc. Lot 3I-Landmark Industrial Park New Hanover Cow* construction, operation and maintenance of a Detention Pond 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 Environmental. Management and considered a part of this permit. This permit shall be effective from the date of issuance until February 28, 2006 and shall be subject to the following specified conditions and limitations: I. DESIGN STANDARDS 1. This permit is effective only with respect to the nature and volume of stormwater described in the application and other supporting data. 2. This stormwater system has been approved for the management of stormwater runoff as described on page 3 of this permit, the Project Data Sheet. 3. Approved plans and specifications for this project are incorporated by reference and are enforceable parts of the permit. 2 State Stormwater Management Systems Permit No. SW8 951105 DIVISION OF ENVIRONMENTAL MANAGEMENT Project Name: Permit Number: Location: Applicant: Mailing Address: Application Date: Water Body Receiving Stormwater Runoff: Classification of Water Body: If Class SA, chloride sampling results: Pond Depth:' Permanent Pool Elevation: Total Impervious Surfaces Allowed: Mite Area entering Pond: Green Area entering Pond: Required Surface Area: Provided Surface Area: Required Storage Volume: Provided Storage Volume: Temporary Storage Elevation: Controlling Orifice: PROJECT DATA !zt 31-Landmark industrial Park 951105 New Hanover County Mr. W. Keith Elmore, President Lyndale Enterprises, Inc. 3808 Oleander Drive Wilmington, North Carolina 28403 November 3, 1995 Barnard's Creek "C Sw" N/A 7 feet 35.5 MSL 49,912 square feet N/A square feet 43,234 square feet 1,935 square feet 2,712 square feet 4,774 cubic feet 4,975 cubic feet 37.04 MSL 1" pipe State Stormwater Management Systems Permit No. SW8 951105 4. The tract will be limited to the amount of built -upon area indicated in the supporting calculations and per approved plans. 5. The following items will require a modification to the permit: a. Any revision to the approved plans, regardless of site. b. Project name change. C. Transfer of ownership. d. Redesign or addition to the approved amount of built -upon area. e. Further subdivision of the project area. - f. Alteration of the approved stormwater conveyances including swales, ditches, and piping. In addition, the Director may determine that other revisions to the project should require a modification to the permit. 6. 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. II. SCHEDULE OF COMPLIANCE 1. The permittee will comply with the following schedule for construction and maintenance of the stormwater management system: a. The stormwater management system shall be constructed in it's entirety, vegetated and operational for it's intended use prior to the construction of any built -upon surfaces except roads. b. During construction, erosion shall be kept to a minimum and any eroded areas of the system will be repaired immediately. 2. The facilities must be properly maintained and operated at all times to assure that the system functions at optimum efficiency. The approved Operation and Maintenance Plan must be followed in it's entirety and maintenance must occur at the scheduled intervals. Activities to include, but not be limited to: a. Semiannual scheduled inspections (every 6 months). b. Sediment removal. C. Mowing and revegetation of side slopes. d. Immediate repair of eroded areas. e. Maintenance of side slopes in accordance with approved plans and specifications. f. Debris removal and unclogging of outlet structure, orifice device and catch basins and piping. g. Access to the outlet structure must be available at all times. 3. Records of maintenance activities must be kept and made available upon request to authorized personnel of DEM. The records will indicate the date, activity, name of person performing the work and what actions were taken. 4 State Stormwater Management Systems Permit No. SW8 951105 4. This permit shall become voidable unless the facilities are constructed in accordance with the conditions of this permit, the approved plans and specifications, and other supporting data. 5. 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 fiow 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. Mail the Certification to the Wilmington Regional Office, 127 Cardinal Drive Extension, Wilmington, North Carolina, 28405, attention Water Quality Section. 6. A copy of the approved plans and specifications shall be maintained on file by the Permittee for a minimum of ten years from the date of the completion of construction. M. GENERAL CONDITIONS 1. . This permit is not transferable. In the event there is a desire for the facilities to change ownership, or there is a name change of the Permittee, a formal permit request must be submitted to the Division of Environmental Management accompanied by an application fee, documentation from the parties involved, and other supporting materials as may be appropriate. The approval of this request will be considered on its merits and may or may not be approved. 2. Failure to abide by the conditions and limitations contained in this permit may subject the Permittee to enforcement action by the Division of Environmental Management, in accordance with North Carolina General Statute 143-215.6(a) to 143-215.6(c). 3. 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) which have jurisdiction. 4. in the event that the facilities fail to perform satisfactorily, including the creation of nuisance conditions, 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. 5. The permit may be modified, revoked and reissued or terminated for cause. The filing of a request for a permit modification, revocation and reissuance or termination does not stay any permit condition. Permit issued this the 29th day of February, 1996. NORTH CAROLINA ENVIRONMENTAL MANAGEUMM CONBUSSION A. r reSTon Howard, jr., P. E. , Director Division of Environmental Management By Authority of the Environmental Management Commission Permit Number. SW8 951105 5 State Stormwater Management Systems Permit No. SW8 951105 Lot 31-Landmark Industrial Park Stormwater Project No. 951105 New Hanover County Engineer's Certification I, , as a duly registered Professional Engineer in the State of North Carolina, having been authorized to observe (periodically/weekly/full time) the construction of the project, (1roject) 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. Signature Registration Number Date T NO V 0 R 1995 NOR= CMOU NA S'I'ORMWATER MANAG1ENW.W PERAW "PUCAMON ...........aaaaanaavaevs�.. I. GENBRAI. INFORMATION 1. Project 2. Location, directions to project include County, Address, State Road) Attach map./ 3.Owner's NameG1�8�/efi/�,�T _L�YG� Phone 4. Owner's Mailing Address_&2 Q��.4/✓��/L �2 city I 5. Application date /% - 9- Pee enclosed $ 3 SE, o 0 6. Nearest Receiving Stream 9Act NA REns t6 /, AG9 F& Mass- 1--:kzj 7.Projectdescription c-tinJSTRycT ®FF/cE.IwAKV-% U5 E AND PAR.KOA/G "7- U. PERNUT WF'ORMATION I. PeranitNo.rroae,#u`din cj(•l} [ S 1 /U S 2. Permit Type ✓ * New Renewal Modification (existing Permit No.) 3. Project Type: Low Densi ✓ D:e:=tio Infiltration Other: Redevelop General Pir Cert 4. Other State/Federal Permits/Approvals Required (cwk appropriate ) LAMA Major Sedimentation/Erosion Control L, 404 Permit M. BUJI.T UPON AREA (newe see 1vra C 2& 1 o0S dux .lw7P,- applicable dmday lbwfa) rai aae PLAWO Break -down cif Imp Mious Area Basin Bain (Pkare bxllrate below Ae desip bWr W*ws area) Classification C SW Buildings o . ✓S6Z A c[RE Allowable Impervious Area Total Project Area O.44 &WE 2.15,lrcJkF- Proposed Impervious Area 1. ! o S Acf % Impervious Area S 1.4 o7e IV, STORMWATER TREATMENT oscriu grow dte term' will be anwd) WET Po!317 Stems _____.,_. Parking/SW •IM Totals t . ! o S ,A- cR 6- V. DEED RESTRICTIONS AND PROTECTIVE COVENANTS Deed restrictions and protective covenants are required to be recorded for all low density projects and all subdivisions prior to the sale of any lot. Please see Attachment A for the specific items that must be recorded for the type of project applied for. By your signature below, you certify that the recorded deed restrictions and protective covenants for this project shall include all the items required by the permit, that the covenants will be binding on all parties and persons claiming under them, that they will run with the land, that the covenant cannot be changed or deleted without concurrence from the State, and that they will be recorded prior to the sale of any lot. VI. OWNER'S CERTWICATION certify that the information included on this permit (Please prim or type none dmriy) application form is correct, that the project will be constructed in conformance with the approved plants, that the deed restrictions will be recorded with all required permit conditions, and that to the best of my knowledge, the proposed project complies with the requirements of 15A NCAC 2H.1000. I authorize the below peon or firm to submit stormwater plans on my behalf. Ow r/Authorized Agent Signature and Title Da VII. AGENT AUTHORIZATION (mwnE coMmLrm) Person or firm name H olJ 6Yc-vTr" EN G) t1EUR1 n/ G C.-v. Mailing Address F. 0. R d x 15036 City W 1 d 1V% 1 nl6 TV tJ State _NC Zip A 8 401? Phone IN 0 - 3 So - O e. 31 Please submit application, fee, plans and calculations to the appropriate Regional Office. cc: ApplicantMRO//Central Files iTODWATER K E C E I W NOV 0 3 1995 rao 2f211 ATTACT A � A LOW DENSITY AND SUBDIVISION PROJECTS GENERAL SUBMUITAL REQUIREMENTS 1. A completed stormwater permit application. 2. Two sets of plans showing north arrow, scale, revision date, property/project boundaries, lot lines, proposed and existing contours, drainage areas, mean high water line, wetlands, easements, the 30' minimum vegetated buffer between impervious areas and surface waters, proposed impervious areas, and road cross -sections. 3. Calculations of the built -upon area, For subdivisions, please show the methodology for arriving at the per lot built -upon area. For non -subdivision projects. please break down the calculation into buildings, roads, parking, and other (include all impervious areas). 4. Low density projects with curb and gutter will require: a. Drainage area delineation and swale locations shown on the plans. b. Detail of the swale, showing minimum 5:1 side slope. C. Velocity calculations, indicating a non -erosive flow for the 10 yr storm. d. inlet and outlet elevations. Maximum longitudinal slope is 5%. a. The type of vegetated cover specified on the plans, U _ i 1 ! .` - The following statements must be included for all low density projects, and for all subdivisions: No more than square feet of any lot. Including dW portion of the right-of-way between the edge of pavement and the front lot line, shall be covered by impervious structures, including asphalt, gravel, concrete, brick, stone, slate or similar material, not including wood decidng or the water surface of .swimming pools. This covenant is intended to ensure continued compliance with the stormwater permit issued by the State of North Carolina. The covenant may not be changed or deleted wlahout the consent of the State. No one may, fill in or pipe any roadside or lot -Brae swele, except as neeessm y to provide a minimum driveway crossing. For curb and gutter projects, no on may pipe, fill in, or alter any lot line swale used to meet North Carolina Stormw+ater Management Permit requirements. NOTE If lot sizes vary significantly, the ovrner/developer must provide an attachment listing each lot number, size, and the allowable built -upon area for each lot. - air. o a �ss� Project Name: POND MAINTENANCE REQUI1Uaff NTS ELMORE WAREHOUSE Responsible Party: KEITH ELMORE Address: 3808 Oleander Dr. Wilmington, NC 28403 .............so............ Project No. 5(,0 S R5 j 105 Phone No. (910) 799-3320 I. Monthly, or after every runoff producing rainfall event, whichever comes first: A. Inspect the trash rack; remove accumulated debris, repair/replace if it is not functioning. B. Inspect and clear the orifice of any obstructions. If a pump is used as the drawdown meclaanis*n, pump operation will be checked. k .log of test runs of the pump willbe kmt on site and made available to DBM personnel upon request. C. Inspect the pond side slopes and grassed inlet swales; remove trash, and repair eroded areas before the next rainfall event. D. If the pond is operated with a vegetated filter, the filter will be checked for sediment accumulation, trash accumulation, erosion and proper operation of the flow spreader mechanism. Repairs/cleaning will be done as necessary. IL Quarterly: A. Inspect the collection system (ie. catch basins, piping, grassed swales) for proper functioning. Accumulated trash will be cleared from basin grates, basin bottoms, and piping will be checked for obstructions and cleared as required. B. Pond inlet pipes will be checked for undercutting, riprap or other energy dissipation structures will be replaced, and broken pipes will be repaired. III. Sem?-annually:. A. Accumulated sediment from the bottom of the outlet structure will be removed. B. The pond depth will be checked at various points. Design depth is 91 ', measured from the orifice height down to the pond bottom. If depth is reduced to 75 % of original design depth or 3 feet, whichever is greater, sediment will be removed to at least the original design depth. C. Grassed swales, including the vegetated filter if applicable, will be reseeded twice a year as necessary. DEC 0 4 1995 PRO] � ® q 5U0 POND MAINTENANCE REQUIREMENTS PAGE 2 IV. General: A. Mowing of the side slopes will be accomplished according to the season. Maximum grass height will be 6" . B. Cattails are encouraged along the pond perimeter, however they will be removed when they cover more than 1/2 the surface area of the pond. C. The orifice/pump is designed to draw down the pond in 2-5 days. If drawdown is not accomplished in that time, the orifice will be replaced with a larger or smaller orifice. Slow drawdown may be attributed tc a clogged sys*w.u. he sill c" c` ;Ue clogging : ,;» be found and eliminated. D. All components of the detention pond system will be kept in good working order. Repair or replacement components will meet the original design specifications as per the approved stormwater plan. If previously approved components are determined to be ineffective, the component must be redesigned and/or replaced. V. Special Requirements: I, • I -fa r I � , hereby acknowledge that I am the financially (please print or type mmne clearly) responsible party for maintenance of this detention pond. I will perform the maintenance as outlined above, as part of the Stormwater Management Permit received for this project. Date. DA/arl: S:\WQS\STORMWAT\FORMS\O&M-POND.FOR State of North Carolina Department of Environment, Health, and Natural Resources Wilmington Regional Office James B. Hunt, Jr. DIVISION OF ENVIRONMENTAL MANAGEMENT Jonathan B. Howes Governor DATER QUALITY SECTION Secretary January 22, 1996 Mr. Jim Honeycutt, P.E. Honeycutt Engineering Post Office Box 902 Wrightsville Beach, North Carolina 28480 Subject: ADDITIONAL INMRMATION Stormwater Project No. SW8 951105 Lyndale Enterprises (Elmore Warehouse) New Hanover County Dear Mr. Honeycutt: The Wilmington Regional Office received a Stormwater Management Permit Application for Lyndale Enterprises (Elmore Warehouse) on December 27, 1995. A preliminary review of that information has determined that the application is not complete. The following information is needed to continue the stormwater review: 1. The forebay weir elevation, as stated in my previous letter, should be above the permanent pool, but below the storage pool elevation, ie., between 35.7 and 37.0. You show it below the permanent pool, therefore the area will not function as a forebay. Please note that this request for additional information is in response to a preliminary review. The requested information should be received by this Office prior to February 22, 1996, or the application will be returned as incomplete. The return of a project will necessitate resubmittal of all required items, including the application fee. If you have any questions concerning this matter please feel free to call me at (910) 395-3900. Sincerely, Ms. Linda Lewis Environmental Engineer DA/arl: S:\WQS\STORMWAT\ADDINFO\951105.JAN cc: Linda Lewis Central Files 127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 • Telephone 910-395-3900 • Fax 910-350-2004 An Equal Opportunity Affirmative Action Employer AITACIMNT A LOW DENSITY AND SUBDIVISION PROJECTS GENERAL SVBMMAL REQUIREMENTS 1. A completed stormwater permit application. i. Two sets of plans showing north arrow, scale, revision date, property/project boundaries, lot lines, proposed and existing contours, drainage areas, mean high water line, wetlands, easements, the 30' minimum vegetated buffer between impervious areas and surface waters, proposed impervious areas, and road cross -sections. 3. Calculations of the built -upon area, For subdivisions, please show the methodology for arriving at the per lot built -upon area. For non -subdivision projects, please break down the calculation into buildings, roads, parking, and other (include all impervious areas). 4. Low density projects with curb and gutter will require: a. Drainage area delineation and swats locations shown on the plans. b. Detail of the swale, showing minimum 5:1 side slope. C. Velocity calculations, indicating a non -erosive flow for the 10 yr storm. d. Inlet and outlet elevations. Maximum longitudinal slope is 5%. Rs The type of vegetated cover specified on the plank. The following statements must be included for all low density projects, and for all subdivisions: No more than - square feet of any lot, including that portion of the right-of-way between the edge of pavement and the front lot line, shall be covered by imperwous structures, including asphalt, gravel, concrete, brick, stone, state or similar material, not including wood decking or the wmer surface ®$swirming pools. This covenant is intended to ensure continued compliance with the stormwaterpermit issued by the State o, f North Carolina. yhe covenant may not be changed or deleted without the consent of the State. No one may, fill in or pipe any roadside or lo"nie swale, except as necessary to provide a minimum driveway crossing. For curb and gutter projects, no on may pipe, ,fill in, or alter any lot line swale used to meet North Carolina Stormwater Management Permit requirements. NOTE If lot sizes vary significantly, the ownerldeveloper moist provide an attachment listing each lot number, size, and the allowable built -upon area for each lot. - Drainage Calculations for Elmore Whse, 411 Landmark Dr. , Wilmington, NC 10113195 Project 5070 Revised 11MA6 Revised 12I26M A total • - 43560 93484 A total - 2.1461 acres ...total area APave d • A pemed = 0.562 ...paged arse 43560 A Sift. = A side = 0.021 acres ...sidewalk area 4931 A boda := 2 500 A bldg = 0.562 acres ...Total area of buildings 43560 A imp := A paw + A Sid@ A imp = 0.583 acres - total impemiouss area excl. bldgs Amp:=Atoms- Aimp- Aug Ado 1 C pro.25 ...C C 1.00 C imp .95 ...paved arse C A Amp Abe C comp := C pre. A total + C imp. mp A total + C A told C COMP p 0.64 ...composite C (post -development) L :- 175 tt ...hydraulic length H 31 ...height -85 () L! T c .= H 128 T c = 1.88 minutes ...t me of concentration T c 5 ...use 5 minutes minimum Intensity -Duration -Frequency Relationships: Values of G and HII R G H 10 252 30 50 338 33 R= Return Period "Source: Master Drainage Plan fbr City of Wilmington ILGILIV�it DEC 2 71"5 U DENT 0IF #.SW -9 QLl00 `**•` � �� � i� 11 �'rrf1r =Q SEAL �r 9524 �zf�5 T := T, Time of duration G10:=252 H10:=30 G10 1 10 := (H 10 + T) G 50 := 338 H 50 := 33 G c^ 150 (H 50 I T) Compute runoff rates: Q pre := C pre' 110' A total Q pre = 3.86 cfs Page 2 110 = 7.2 inlhr ...10 year storm intensity 150 = 8.895 in/hr ...50 year storm ..pre -development runoff from 10 yr. storm Q 10 := C comp' 110' A total 0,009.84 cfs ... post -development discharge rate from 10 yr. storm Q 50 C comp' 150-A tote! Q 50 = 12.16 cfs ...post -development discharge rate from 50 yr. storm Volume of runoff from developed area of slte: P := 4.8 in Soil type = Murville Pine Sand Chl := 69 Curve No. S ('000� 10 S = 4.493 CIV 1 R (P - 0.2- S )2 R = 1.813 in. ... runoff depth depth P + .8- S depth p R vol R depth' (A total)' 43560.1 12 R Vol = 14126 cubic feet ...total runoff volume T P R depth' to total) ).43560. 1 1.39•(Q 10) t12/ 60 T P = 17.21 ...time to peak flow Determine size of 7' deep pond without vegetative filter: Page 3 IMP% .- A imp + A bldg IMP% = 0.534 A total IMP% 50 :_ .019 IMP% fi0 :_ .024 IMP := IMP% 50 + (IMP% 60 IMP% 50)• .34 IMP = 0.0207 DA := A total-43560 SA := (IMP)-DA SA = 1935 Determine storage volume required for treatment of first Inch of runoff: C comp = 0.637 V := 2. A total- 43560• C comp V = 4961 cubic feet Assume 50' x 35' pond with half circles on ends. Solve for depth "d" to provide required storage: 1 := 50 w .- 35 w• I = 1750 W 1 + (W)2 . R = 2712 Compute volume of water over 6:1 sloped2 shelf: d 1 1 ft V 1 := 1W2 w 2 (1•W) + I• (w + 12•d 1� + �• 2 + n• 2 + 6-d 1 l J 2 Compute remaining volume required: V2:=V-V1 V2=1563 d := 1 ...guess value d 1 V 1 = 3399 cu.ft. W Z W 2 [I•(W+ 12•d 1)] + (I)•(w+ 6•d + 12•d 1� + 2 + 3•d + (6-d 1� •n+ 2 + �6•d 1� •a f(d) -- d 2 g(d) := V 2 .._function of d for pond wi3:1 side slopes d := root((f(d) - g(d)),d) d = 0.37 ft. - additional depth required depth := d 1 + d depth = 1.37 ft. - total depth required to provide 1" storage V Q 2day 2.24.60. 00 V Q Sday 5.24.80.60 g 32.2 h:=d 2 A orifice h = 0.185ft Q 2day = 0.0287 cis ...Max discharge for 2 day drawdown Q 5day = 0.0115 cfs... Max discharge for 5 day drawdown Q 2day C d_(2.g.h)" .5 D := 4. A orifice .12 3.14 C d :_ .6 ...orifice coefficient ...avg. head A orifice = 0.014 Square ft. D = 1.595 in. - for 2 day drawdown Q 5day = 0.0115 cfs A orifice Q 5day 5 A orifice = 0.006 Square ft. C d_(2_g_h). .5 D 4• A orifice • 3.14 12 D = 1.009 in - for 5 day drawdown Use 1.00 inch diameter pipe in routing chart Check capacity of emergency spillway to pass 50 year peak flow: L : = 12 ft ... Length of weir H 2 ft ...Driving head C w := 3.0 ...Weir coefficient Q .= C y( L- H1.5 ...Weir capacity Q = 12.73 must be => Q 50 = 12.16 O.K. Find normal depth in swales with grass as a permanent lining: Q := C bldg-1 10- A bldg Q = 2.025 Am in swale in cfs 2 B := 0 ...bottom width of channel (ft) M := 5 ...side slopes s 41.5175 0.5 s = 0.006 ...channel slope n 0.13 ...roughness coeff. for grass lined channels Retardance Class D (cut) based on V x R below Z roq := Q•n Z req = 2.337..2 required (from R.Malcolm) 1.49• �s Page 4 y :_ .90 ...depth of flow (ft.) - vary this number until Zav (below) is approx. equal Page 5 to Z.req (above) when n (above) is appropriate for V x R (below) A := B-y + M. (y)2 ...Cross -sectional area of flow (sq.ft.) at depth y P := B + 2-y- 1 + M2 ...Wetted perimeter (ft.) at depth y R := P ...Hydraulic radius (ft.) at depth y 2 Z av A- (R) 3 Z av = 2.347 ...Z available Compute velocity at this depth: 2 1 V := 1.49 R3-s2 V = 0.502 fps n V- R = 0.222 Using this value, choose n from Figure 8.05c page 8.05.7 and adjust n above until consistent From Table 8.05a page 8.05.4: V p : = 5.0 fps - Permissible Velocity for channels lined with bermudagrass with slopes 0-5% in easily erodible non -plastic soils Since V:SVp. channel lining O.K. Determine outlet apron dimensions and riprap size for discharge into pond: From pipe chart V := 6.2 fps D := 1.25 ft La := 9 ft - minimum length of apron from figure BMW W := D + A- L a W = 4.85 ft - minimum width of apron from figure 8.06b d 50 := 4 diameter of stone in inches d max := 1.5- d 50 d max = 6 diameter of stone in inches t := 1.5. d max t = 9 thickness of apron in inches REFER TO ATTACHED SHEETS FOR ROUTING RESULTS Note: References to chart nos., table nos., and page nos. refer to Erosion and Sediment Control Planning and Design Manual unless noted otherwise s z CONTOUR INCR ACCUM CONTOUR AREA VOL VOL STAGE In S In Z Z eat 35.67 2712 0 0 0.00 0.00 36.17 3370 1521 1521 0.50 7.3269 -0.6931 0.51 36.67 4085 1864 3384 1.00 8.1269 0.0000 0.99 37.04 4364 1563 4947 1.37 8.5086 0.3148 1.35 37.67 4856 2904 7852 2.00 8.9685 0.6931 1.98 38.17 5263 2530 10381 2.50 9.2478 0.9163 2.49 38.67 5684 2737 13118 3.00 9.4818 1.0986 3.02 39.17 6119 2951 16069 3.50 9.6846 1.2528 3.57 Regression Output: Constant 8.143117 Ks-- 3440 Std Err of Y Est 0.019977 b= 1.21 R Squared 0.999522 No. of Observations 7 X Coefficient(s) 1.211798 Std Err of Coef. 0.011849 STAGE -DISCHARGE FOR RISER/BARREL SPILLWAY WITH EMERGENCY WEIR RISER/BARREL: 7.5 Dr = 3.516 Area of grate openings Etop = 37.04 Elev. top riser (ft) Cwr = 3 Riser weir coefficient Cdr = 0.59 Riser orifice coefficient Do = 1.00 Orifice dia.(in) Einv = 35.67 Elev inv. orifice (ft) Co = 0.6 Orifice coeff. Db = 1.25 ft. Binv = 35.60 Barrel invert Cdb = 0.6 EMERGENCY WEIR: Cw = 3 Weir coefficient Ecr = 37.50 Elev. weir crest (ft) LW = 12 Weir length (ft) 1 2 3 4 5 6 7 13 Stage Riser Riser Barrel 1" Princ. €merg. Total (weir) (orifice) orifice Spillway Weir Outflow [ftl Ids] Ids] Ids] Ids] Ids] Ids! Ids] 35.67 0.00 0.00 0.00 0.00 0.00 0.00 0.00 35.87 0.00 0.00 0.00 0.01 0.00 0.00 0.01 36.07 0.00 0.00 0.00 0.02 0.00 0.00 0.02 36.27 0.00 0.00 0.00 0.02 0.00 0.00 0.02 36.47 0.00 0.00 0.00 0.02 0.00 0.00 0.02 36.67 0.00 0.00 0.00 0.03 0.00 0.00 0.03 36.87 0.00 0.00 0.00 0.03 0.00 0.00 0.03 37.07 0.12 2.88 7.16 0.03 0.12 0.00 0.15 37.27 2.48 7.98 7.63 0.03 2.48 0.00 2.52 37.47 6.34 10.92 8.08 0.04 6.34 0.00 6.38 37.67 11.25 13.21 8.50 0.04 8.50 2.52 11.02 37.87 17.01 15.17 8.90 0.04 8.90 8.10 17.00 38.07 23.52 16.90 9.28 0.04 9.28 15.49 24.77 38.27 30.69 18.46 9.65 0.04 9.65 24.32 33.97 38.37 34.51 19.20 9.83 0.04 9.83 29.21 39.04 38.47 38.48 19.91 10.01 0.04 10.01 34.39 44.40 38.57 42.58 20.59 10.18 0.04 10.18 39.85 50.02 F- 17 M gn aoavr��a 9'9£ 9'9£ £'9£ VK TLC WO s L-LE 9'L£ £'L£ V L£ 8'9£ L'9£ 9'9£ £'9£ L'9£ 6'9€ 0 Cd o 0 7OW140ma v uw 9'8£ o r z Yes M W £'L£ 6'9£ 9'9£ V9£ LIC CWAINSAW ROUTING Input data: Qp= 9.84 RESULTS: Tp= 17.2 OUTFLOW PEAK= 6.72 MAX STAGE= 37.50 dT= 1.7 Ks= 3440 b= 1.21 7.5 Etop = 37.04 Top of riser Dr = 3.516 Area of grate openings Db= 1.25 Binv= 35.60 N= 1 No. of orif. Cd= 0.6 Orifice coeff. D= 1 Dia. of orifice Zi= 35.67 Inv. elevation CW= 3 Weir Coefficient L= 12 Length of overflow weir Zcr= 37.5 Elev. of overflow weir 1 2 3 4 5 6 7 8 TIME INFLOW STORAGE STAGE OUTFLOW ORIFICE WEIR RISER/ [min', [cis] [Nu ft] [ft] [cfe] [de] [cFe] BARREL 0 0.00 0 35.67 0.00 0.000 0.00 0.00 1.7 0.24 0 35.67 0.00 0.000 0.00 0.00 3.4 0.92 24 35.69 0.00 0.000 0.00 0.00 5.1 1.98 118 35.73 0.00 0.003 0.00 0.00 6.8 3.33 319 35.81 0.01 0.008 0.00 0.00 8.5 4.83 658 35.93 0.01 0.012 0.00 0.00 10.2 6.33 1149 36.07 0.02 0.016 0.00 0.00 11.9 7.70 1793 36.25 0.02 0.019 0.00 0.00 13.6 8.81 2577 36.46 0.02 0.023 0.00 0.00 15.3 9.54 3473 36.68 0.03 0.026 0.00 0.00 17 9.84 4444 36.91 0.03 0,029 0.00 0.00 18.7 9.66 5445 37.13 0.65 0,031 0.00 0.62 20.4 9.03 6364 37.33 3.58 0.033 0.00 3.54 22.1 8.04 6920 37.45 5.95 0.035 0.00 5.92 23.8 7.07 7134 37.50 6.69 0.035 0.00 6.65 25.5 8.22 7173 37.50 6.72 0.035 0.01 6.67 27.2 5.47 7123 37.49 6.68 0.035 0.00 6.64 28.9 4.81 7000 37.47 6.32 0.035 0.00 6.29 30.6 4.23 6846 37.43 5.61 0.034 0.00 5.58 32.3 3.72 6705 37.40 4.99 0.034 0.00 4.96 34 3.27 6576 37.38 4.44 0.034 0.00 4.40 35.7 2.88 6457 37.35 3.95 0.034 0.00 3.91 37.4 2,53 6348 37.33 3.51 0.033 0.00 3.48 39.1 2.23 6248 37.31 3.13 0.033 0.00 3.10 40.8 1.96 6156 37.29 2.79 0.033 0.00 2.76 42.5 1.72 6071 37.27 2.49 0.033 0.00 2.45 44.2 1.52 5994 37.25 2.22 0.033 0.00 2.19 45.9 1.33 5922 37.24 1.98 0.032 0.00 1.95 47.6 1.17 5856 37.22 1.77 0.032 0.00 1.74 49.3 1.03 5795 37.21 1.58 0.032 0.00 1.55 51 0.91 5739 37.20 1.41 0.032 0.00 1.38 52.7 0.80 5687 37.18 1.27 0.032 0.00 1.23 54.4 0.70 5639 37.17 1.13 0.032 0.00 1.10 56.1 0.62 5595 37.16 1.02 0.032 0.00 0.98 57.8 0.54 5555 37.16 0.91 0.032 0.00 0.88 59.5 0.48 5517 37.15 0.32 0.031 0.00 0.79 61.2 0.42 5482 37.14 0.73 0.031 0.00 0.70 62.9 0.37 5450 37.13 0.66 0.031 0.00 0.63 64.6 0.32 5421 37.13 0.59 0.031 0.00 0.56 66.3 0.29 5393 37.12 0.53 0.031 0.00 0.50 68 0.25 5368 37.11 0.48 0.031 0.00 0.45 69.7 0.22 5344 37.11 0.43 0.031 0.00 0.40 71.4 0.19 5322 37.10 0.39 0,031 0.00 0.36 73.1 0.17 5302 37.10 0.35 0.031 0.00 0.32 74.8 0.15 5283 37.10 0.32 0.031 0.00 0.29 76.5 0.13 5266 37.09 0.29 0.031 0.00 0.26 1 2 3 4 5 6 7 8 TIME INFLOW STORAGE STAGE OUTFLOW ORIFICE WEIR RISERI [n'n1 [del ICU ft] [ft] [cfsl [cfsl [Cfs] BARREL 78.2 0.12 5250 37.09 0.26 0.031 0.00 0.23 79.9 0.10 5235 37.08 0.24 0.031 0.00 0.21 81.6 0.09 5221 37.08 0.22 0.031 0.00 0.19 83.3 0.08 5208 37.08 0.20 0.031 0.00 0.17 85 0.07 5195 37.08 0.18 0.031 0.00 0.15 95 0.03 5129 37.06 0.10 0.030 0.00 0.07 105 0.02 5090 37.05 0.06 0.030 0.00 0.03 115 0.01 5064 37.05 0.04 0.030 0.00 0.01 125 0.00 5044 37.04 0.03 0.030 0.00 0.00 135 0.00 5027 37,04 0.03 0.030 0.00 0.00 145 0.00 5010 37.03 0.03 0.030 0,00 0.00 155 0.00 4992 37.03 0.03 0.030 0.00 0.00 165 0.00 4974 37.03 0.03 0.030 0.00 0.00 175 0.00 4956 37.02 0.03 0.030 0.00 0.00 185 0.00 4938 37.02 0.03 0,030 0.00 0.00 195 0.00 4920 37.01 0.03 0.030 0.00 0.00 205 0.00 4902 37.01 0.03 0.030 0.00 0.00 215 0.00 4884 37.01 0.03 0.030 0.00 0.00 225 0.00 4866 37.00 0.03 0.030 0.00 0.00 235 0.00 4848 37.00 0.03 0.030 0.00 0.00 245 0.00 4831 38.99 0.03 0.030 0.00 0.00 255 0.00 4813 36.99 0.03 0.030 0.00 0.00 265 0.00 4795 36.99 0.03 0,030 0.00 0.00 275 0.00 4777 36.98 0.03 0.030 0.00 0.00 285 0.00 4759 36.98 0.03 0.030 0.00 0.00 295 0.00 4742 36.97 0.03 0.029 0.00 0.00 315 0.00 4706 36.97 0.03 0.029 0.00 0.00 335 0.00 4671 38.96 0.03 0.029 0.00 0.00 355 0.00 4636 38.95 0.03 0.029 0.00 0.00 375 0,00 4601 36.94 0.03 0.029 0.00 0.00 395 0.00 4588 36.93 0.03 0.029 0.00 0.00 415 0.00 4531 36.93 0.03 0.029 0.00 0.00 435 0.00 4496 36.92 0.03 0.029 0.00 0.00 455 0.00 4462 36.91 0.03 0.029 0.00 0.00 475 0.00 4427 36,90 0.03 0.029 0.00 0.00 495 0.00 4393 36.89 0.03 0.029 0.00 0.00 515 0.00 4359 36.89 0.03 0.028 0.00 0.00 535 0.00 4325 36.88 0.03 0.028 0.00 0.00 555 0.00 4291 36.87 0.03 0.028 0.00 0.00 575 0.00 4257 36.86 0.03 0.028 0.00 0.00 595 0.00 4223 36.65 0.03 0.028 0.00 0.00 625 0.00 4172 36.84 0.03 0.028 0.00 0.00 655 0.00 4122 36.83 0.03 0.028 0.00 0.00 685 0.00 4072 36.82 0.03 0.028 0.00 0.00 715 0.00 4022 36.81 0.03 0.027 0.00 0.00 745 0.00 3973 36.80 0.03 0.027 0.00 0.00 1 2 3 4 5 6 7 8 TIME INFLOW STORAGE STAGE OUTFLOW ORIFICE WEIR RISER/ [min] [mil ICU ftl [ftl [mil [ef6l [cf61 BARREL 775 0.00 3924 36.78 0.03 0.027 0.00 0,00 605 0.00 3875 36.77 0.03 0.027 0.00 0.00 835 0.00 3826 36.76 0.03 0,027 0.00 0.00 865 0.00 3778 36.75 0.03 0.027 0.00 0.00 895 0.00 3730 36.74 0.03 0.027 0.00 0.00 925 0.00 3682 36.73 0.03 0.026 0.00 0.00 955 0.00 3634 36.72 0.03 0.026 0.00 0.00 985 0.00 3587 36.71 0.03 0,026 0.00 0.00 1015 0.00 3540 36.69 0.03 0.026 0.00 0.00 1075 0.00 3446 36.67 0.03 0.026 0.00 0.00 1135 0.00 3353 36.65 0.03 0.025 0.00 0.00 1195 0.00 3262 36.63 0.03 0.025 0.00 0.00 1255 0.00 3172 36.61 0.02 0.025 0.00 0.00 1315 0.00 3082 36.58 0.02 0.025 0.00 0.00 1375 0.00 2994 36.56 0.02 0.024 0.00 0.00 1435 0.00 2907 36.54 0.02 0.024 0.00 0.00 1495 0,00 2821 36.52 0.02 0.024 0.00 0.00 1555 0.00 27W 36.50 0.02 0.023 0.00 0.00 1615 0.00 2652 36.48 0.02 0.023 0.00 0.00 1675 0.00 2569 36.46 0.02 0,023 0.00 0.00 1735 0.00 2488 36.44 0.02 0.022 0.00 0.00 1795 0.00 2408 36.41 0.02 0,022 0.00 0.00 1855 0.00 2328 36.39 0.02 0.022 0.00 0.00 1915 0.00 2250 36.37 0.02 0.021 0.00 0.00 2155 0.00 1942 36.29 0.02 0.020 0.00 0.00 2395 0.00 1654 36.22 0.02 0.019 0.00 0.00 2635 0.00 1385 36.14 0.02 0.017 0.00 0.00 2875 0.00 1137 36.07 0.02 0.016 0.00 0.00 3115 0.00 911 36.00 0.01 0.014 0.00 0.00 3355 0.00 706 35.94 0.01 0.013 0.00 0.00 3595 0.00 525 35.88 0.01 0.011 0.00 0.00 3835 0.00 369 35.83 0.01 0.009 0.00 0.00 4075 0.00 240 35.78 0.01 0.007 0.00 0.00 4315 0.00 140 35.74 0.00 0.004 0,00 0.00 4555 0.00 79 35.71 0.00 0.002 0.00 0.00 4795 0.00 49 35.70 0.00 0.001 0.00 0.00 5035 0.00 32 35.69 0.00 0.001 0.00 0.00 5275 0.00 22 35.69 0.00 0,000 0.00 0.00 5515 0.00 16 35.68 0.00 0.000 0.00 0.00 5755 0.00 12 35.68 0.00 0.000 0.00 0.00 5995 0.00 9 35.68 0.00 0.000 0,00 0.00 6235 0.00 7 35.68 0.00 0.000 0.00 0.00 6475 0.00 5 35.67 0.00 0,000 0.00 0.00 6715 0.00 4 35.67 0.00 0,000 0.00 0.00 6955 0.00 4 35.67 0.00 0.000 0.00 0.00 `YJ is r-1 u 0 o a:a ca o a4 o 0 C Oi W r` m Id It V) Od r O P (Iwo) sevvwma State of North Carolina Department of Environment, Health, and Natural Resources Wilmington Regional Office James B. Hunt, Jr. DIVISION OF ENVIRONMENTAL MANAGEMENT Jonathan B. Howes Governor WATER QUALITY SECTION Secretary December 18, 1995 Mr. Jim Honeycutt, P.E. Honeycutt Engineering Post Office Box 15036 Wilmington, North Carolina 28409 Subject: ADDITIONAL INFORMATION Stormwater Project No. SW8 951105 Lyndale Enterprises New Hanover County Dear Mr. Honeycutt: The Wilmington Regional Office received a Stormwater Management Permit Application for Lyndale Enterprises on December 4, 1995. A preliminary review of that information has determined that the application is not complete. The following information is needed to continue the stormwater review: 1. Please provide 2 more sets of plans. The ones you sent were so light that I could not see the proposed drainage structures and pipes. 2. 1 have enclosed a typical forebay section detail. The area around the inlet pipe should be shown correctly in contour to have a shallow area with the back wall of earth or rock slightly higher than the permanent pool elevation. The contour you have shown does not make sense. You show the 38 and the 37.04 connecting together- that is impossible. Additionally, a 6:1 vegetated shelf must be shown around the pond- I forgot to mention that in the last letter. The rules do not state a minimum width for the shelf, but so far 6' is very. Popular. 127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 • Telephone 910-395-3900 • Fax 910-350-2004 An Equal Opportunity Affirmative Action Employer Mr. Honeycutt December 18, 1995 Stormwater Project No. SW8 951105 Please note that this request for additional information is in response to a preliminary review. The requested information should be received by this Office prior to January 18, 1996, or the application will be returned as incomplete. If you have any questions concerning this matter please feel free to call me at (910) 395-3900. Sincerely, Ms. Linda Lewis Environmental Engineer DA/arl: S:\WQS\STORMWAT\ADDINFO\951105.DEC cc: Linda Lewis Central Files 2 Wet ponds can be used to con- trol runoff from larger contrib- uting areas than many other BMPs. However, they take up larger land areas within devel- opments due to the increased storage volume in the perma- nent pool. If sited and main- tained properly, they can be at- tractive features within a devel- opment, enhance property val- ues and offer recreation oppor- tunities. However, ponded wa- ter can attract children creating a safety hazard. The construc- tion of a shallow safety bench around the pond or fencing may be necessary. Construction costs are generally higher than for dry basins, because of the additional volume required for the permanent pool. Marsh plants �r Inlet Riprap inlet protection 1 Forebay .r . Embankment with marsh plants and spillway to main pool stormwater Riser prevents ' over Normal storage volume flowing embankment i' pool level Reverse -sloped orifice to � t t slow) release stormwater Cow '1. Maximum Y Compacted -earth `;�• i waterlevel embankment Main ► ( tr�I Riprap outlet pool k"..' "9'<fq� i protection L:�r z= " Concrete anti- MG -seep flotation anchor collars Figure 11: Wet Retention Pbnd - Side Cutaway View. (Source: Arnold, et al. 1993) Frequent maintenance of wet ponds is required and can be costly. Wet sediment is harder and more costly to remove. Again, easy access is critical to proper maintenance. Poor maintenance can cause the pond to fail, and create nuisance odors, insects, algae blooms and unsightly areas. The NC Division of Environmental Management requires the use of wet ponds to treat stormwater runoff in high density developments within the watersheds of some sensitive water bodies (high quality/outstand- ing resource waters, etc.). DEM should be consulted on specific design and operation and maintenance requirements. Many local governments also require vet ponds within water supply watersheds and should be contacted for further information. Guilford County, North Carolina has extensive experience with wet retention ponds, %%ith over 135 installed since 1984. Contact Lee Stimpson, Watershed Protection Engi- neer at (919) 373-3784 for more information. State of North Carolina Department of Environment, Health, and Nagai Wilmington Regional Office James B. Hunt, Jr. DIVISION OF ENVIRONMENTAL MANAGEMENT Governor WATER QUALITY SECTION November 20, 1995 Mr. Jim Honeycutt, P.E. Honeycutt Engineering Post Office Box 15036 Wilmington, North Carolina 28409 Resources Jonathan B. Howes Subject: ADDITIONAL INFORMATION Stormwater Project No. SW8 951105 Lyndale Enterprises -Elmore Warehouse New Hanover County Dear Mr. Honeycutt: Secretary The Wilmington Regional Office received a Stormwater Management Permit Application for Lyndale Enterprises -Elmore Warehouse on November 3, 1995. A preliminary review of that information has determined that the application is not complete. The following information is needed to continue the stormwater review: _ /1. One more set of plans. A. Signed Operation and Maintenance Plan. (Blank copy enclosed) Please provide either finished contours for the swales along the sides of the building, or specify a slope f the swale on the plans. 2 00 da+OI /4. Design forebays for the inlet pipes, and show a detail on the plans. r/ 5. Where is the grassed overflow spillway? There is a rectangular object shown in the middle of the entrance drive that is not labelled. If this is the spillway, I suggest - that you take the requirement for Bermudagrass sod along it's entire length. f6. Drainage patterns at the entrance drive are unclear. If elevation 37.5 is used as the lowest points, there is no way for the runoff to enter the pond due to the 38 contour which surrounds it. Also, there are no interior swales to pick up this water, and no catch basins to redirect this runoff into the pond. Please clarify. Pry QS O i50 !IOhXl l �-� CP 127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 0 Telephone 910-395-3900 • Fax 910-350 2004 nV 5p 5 Wsut Or An Equal Opportunity Affirmative Action Employer Mr. Honeycutt November 20, 1995 Stormwater Project No. SW8 951105 ---------------------------------------------- 7. There is an — 600 square foot difference in our sidewalk calculations, and a 400 square foot difference in our parking calculation, neither of which causes problems with the pond's design, but I just wanted you to know. 8. Please add more spot elevations to the parking area in front of the building in order to establish the drainage pattern there. Please note that this request for additional information is in response to a preliminary review. The requested information should be received by this Office prior to December 20, 1995, or the application will be returned as incomplete. If you have any questions concerning this matter please feel free to call me at (910) 395-3900. Sincerely, /� 4�, 61�" Ms. Linda Lewis Environmental Engineer DA/arl: S:\WQS\STORMWAT\ADDINFO\951105.NOV cc: Linda Lewis Central Files 2