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HomeMy WebLinkAboutSW8910405_HISTORICAL FILE_19910604STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW8 0 S DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS HISTORICAL FILE ❑ COMPLIANCE EVALUATION INSPECTION DOC DATE Iggl 06 04- YYYYMMDD -- , State of North Carolina Department of Environment, Health, and Natural Resources Wilmington Regional Office James G. Martin, Governor Vlilliam W. Cobey, Jr., Secretary June 4, 1991 DIVISION OF ENVIRONMENTAL MANAGEMENT Mr. Thomas H. Nunalee, III, President Cross Seed Company Post Office Box 269 Wilmington, North Carolina 28402 Dear Mr. Nunalee: Bob Jamieson Regional Manager Subject: Certification of Compliance with Stormwater Regulations Stormwater Project No. 910405 Cross Seed Company New Hanover County This Certification is pursuant to the application for the Cross Seed Company received on April 9, 1991, with additional information received on May 17, 1991. Based on our review of the project plans and specifications, we have determined that the stormwater control system complies with the Stormwater Regulations set forth in Title 15A NCAC 2H.1003(i). The runoff will be treated in a detention pond sized to achieve 90% reduction in Total Suspended Solids. This Certification shall be effective from the date of issuance until rescinded. The project shall be constructed and maintained in accordance with the plans and specifications approved by the Wilmington Regional Office. A professional engineer must certify that the stormwater system has been installed in accordance with the approved plans and specifications upon completion of construction. The attached certification should be received by this Office within 30 days of completion of construction. Continued 127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 • Telephone 919-395-3900 • Fax 919-350-2004 An Equal Opportunity Affirmative Action Employer Mr. Nunalee June 4, 1991 Page Two ---------------- If you have any questions concerning this matter, please call Alexis Finn or me at (919) 256-4161. Sincerely, -Dave Adkins Water Quality Supervisor DA/ai.f: 910405.JUN cc: Mrs. Linda Phillips, Siteworks Design Group Sky Conklin John Parker, DCM Bill Mills Jim Herstine Alexis Finn CWiaming-to n-Regional=0,ff_ice� Central Files DIVISION OF ENVIRONMENTAL MANAGEMENT Evaluation of Stormwater Treatment and Disposal System Draining to Waters Other Than Class SA PROJI':CT DATA Project Name: Cross Seed Company Project No.: 910405 Location (County, Township/Municipality, Address): New Hanover County Applicant Name: Mr. Thomas H. Nunalee, III, President Mailing Address: Post Office Box 269 Wilmington, North Carolina 28402 Submittal.Date: April 9, 1991 Water Body Receiving Stormwater Runoff: Smith Creek Classification of Water Body: "C Swamp" WET DETENTION POND EVALUATION 1. Yes No The design storage is for the runoff from all impervious surfaces resulting from 1-inch of rainfall and is located above the permanent pool. 2. Yes No The permanent pool is designed for 90% TSS removal. Therefore, no vegetative filter is required. 3. Yes No The runoff completely draws down to the permanent pool in 5 days, but not less than 2 days. 4. Yes No The mean depth of the permanent pool is a minimum of 3 feet;. 5. Yes No The inlet structure is designed to minimize turbulence and short circuiting. 6. Yes No An appropriate operation and maintenance plan has been provided for the system. Continued WET DETENTION POND EVALUATION CONTINUED 7. Yes No THIS PROJECT MEETS THE STORMWATER CONTROL REQUIREMENTS OF 15A NCAC 2H.1003 (g), (i), (k), and (1) (For Yes, 1 through 7 must all be circled Yes.) Brief Explanation: The surface area of this detention pond has been designed to remove 90% TSS without the aide of a vegetative filter. DIVISION OF ENVIRONMENTAL MANAGEMENT SIGN -OFF Wilmington Regional Office l � i Date Individual Evaluating Form/Plans 7 D fti e f;' cc: Applicant/WiRO/Mills/CF Water ,Quality egional Supervisor / ITEWORKS -S Design Group, P.A. May 16 1991 Ms. Alexis Finn 127 Cardinal Dr. Ext. Wilmington, NC 28405 RE: Cross Seed Additional Information File # 91015-9 Dear Alexis: 919/799-6808 I received your letter of May 8, 1991. Your questions are answered below. Two sets of revised prints are included. 1. Storm water is routed to the pond from the gravel area and part of the building by the swale on the northeast property line and by a Swale built into the pavement on the northwest asphalt. Sheet flow occurs from -the paved area and enters the two swales that lead to the pond. W�� s_ �(��'';' 2. The concrete swale is extended to 33.8 MSL�and rip rap �531 is added at the outlet. sp. 101(.S <y 3. As discussed, there are 2 separate pond calculations. In talking with Larry, we have decided to build a pond now to 1.95"'0, 4L.accept the future impervious area. 4. Wetlands do not exist. 5. Receiving stream characteristics - See attached sheet. If you have any other questions, please do not hesitate to call. Sincerely, SITEWORKS DESIGN GROUP, P.A. ?� I y ,J,0*1 D E M 1(b PROJ # g/oyoS 4006 Oleander Dr., Suite 3 0 P.O. Box 3988 0 Wilmington, North Carolina 28406-3988 �s-15-9/ 9/alS FICA Ve%/i4 1. I-055 ,.:;c: c. Q� C5 Area = 31.5 s-F We4cc( ffrimefer, P, = l77' slope = 1. 3Co % n = „ D 3 C Heavy �ecJefafeo�� r 14 r z/? 2Cp8 CPS CE�risfin�r% Y = A = si. S = F, S Fps CExr's>S'nq There are gees onJ underbrush gYowinq along -Ae honks o-F -lhe di fch. The Plan) clear1,y shows fha-F the clearing wll no-t ol/sfur/J- Jgrisfi'nJc vgei afi'on on Jei+her ,lcle o-F fhe d'fch For a Jisfance o-F a-f leas+ V 1r-cm -!he censer of -Me --1- 7- F DEL-] L +-li 711 i I T- State of North Carolina Department of Environment, Health, and Natural Resources Wilmington Regional Office James G. Martin, Governor William W. Cobey, Jr., Secretary May 8, 1991 DIVISION OF ENVIRONMENTAL MANAGEMENT Mrs. Linda Lewis Siteworks Design Group Post Office Box 3988 Wilmington, North Carolina 28406-3988 Subject: Additional Information Stormwater Project No. 910405 Cross Seed Company New Hanover County Dear Mrs. Lewis: Bob Jamieson Regional Manager The Wilmington Regional Office received a Stormwater Management Plan for the Cross Seed Company on April 9, 1991. A preliminary review has determined that the submittal for the subject project is not complete. The following information is needed to continue the stormwater review: 1. How is stormwater runoff being routed from the building and parking areas to the detention pond? 2. This Office recommends extending the concrete inlet swale to 2 ft. below the NWL, e.g. 33.8' MSL and the addition of rip rap. 3. Please check your calculations of the following values. A discrepancy exists in our calculations of the following: a. Required SA of the permanent pool = 11592 sf b. 1.0" < orifice < 1.6" 4. If applicable, delineate wetlands and provide U.S. Army Corps of Engineers documentation. If wetlands do not exist, please indicate in writing. 5. Provide receiving stream characteristics. Continued 127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 • Telephone 919-395-3900 • Rtx 919-350-2004 An Equal Opportunity Affirmative Action Emolover �iScroF rc..l @ �.OP AM pooQ Mrs. Lewis May 8, 1991 Page Two This information should be received by this office no later than June 10, 1991, or your project will be returned as incomplete. Construction of the subject project may not commence prior to approval of the Stormwater Management Plan. If you have any questions, you may call me at telephone number (919) 395-3900. Sincer ly, Ms. Alexis I. Finn Environmental Engineer AIF: 910405.MAY cc: c(_2_)_Arexs-Fnn�:7 Bill Mills Central Files ITEWORKS Ail S Design Group, P.A. April 8, 1991 Ms. Alexis Finn DEHNR 127 Cardinal Dr. Ext. Wilmington, NC 28405 RE: Cross Seed Co. Site Plan File u 91015-5 Dear Alexis: 919/799-6808 Attached for your review are 2 grading plans, calculations, the Operation and Maintenance manual, and the signature authorization form. A copy of the topography map used to calculate the off -site drainage is also included. A copy of this plan and the required information is filed with Jim Craig of New Hanover County for Erosion Control approval. If you need more information, please do not hesitate to call. Sincerely, SITTEWORKS DESIGN GROUP, P.A. OC,fi»Gta�� Linda Lewis jECEIVE0 1991 ap^ ci •® DEM PiOj if roNo� 4006 Oleander Dr., Suite 3 0 P.O. Box 3988 ■ Wilmington, North Carolina 28406-3988 Division of Enviromental Management 7225 Wrightsville Ave. Wilmington, NC 28403 RE: Stormwater Signature Authorization File 0 91015 TO: D.E.M. 1, Cross Seed Company, the stormwater review, hereby grant signature of authority to submit stormwater review. Sincerely, 44vr4-4 -- ---------- ----- THOMAS H. NLNALEE, 111 PRESIDENT owner of the property under Siteworks Design Group, P.A. plans and calculations for I, ( ()j2 a Notary Public of the County of _ State of North Carolina, hereby certify that personally before me this day and under oath acknowledge that the above form was executed by him. Witness my han and notarial seal this �_ day of My commissiofn� expires VU1�go2_ Signature _— �]) ECE 9 1'/ LS �rl ILfn�( APP 1 191 U DEM PRpJ g10yoS Data for CROSS SEED CO. 91015 Prepared by SITEWORKS DESIGN GROUP, P.A. 2 Apr 91 HVdroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems SUBCATCHMENT 1 to 9999 RUNOFF BY RATIONAL METHOD: DURATION= 10 MIN INTEN= 6.40 IN/HR SUBCAT AREA LEN SLOPE. Tc WGT'D PEAK NUMBER (ACRE) (FT) (0) (MIN) --- GROUND COVERS (0CN) --- CN C (CFS) 1 1.00 - - 5 100000 - - - - .90 5.9 2 .30 - - 16 100000 - - - - .35 .3 3 .30 - - 7 100000 - - - - .90 1.6 4 1.10 - - 10 100000 - - - - .90 5.2 5 .40 - - 11 100 000 - - - - .35 .7 6 .20 - - 4 100000 - - - - .90 1.2 7 .30 - - 18 100000 - - - - .35 .3 8 5.00 - - 30 100000 - - - - .25 2.2 9 17.50 - - 22 100000 - - - - .50 21.0 10 2.50 - - 9 100000 - - - - .85 11.3 11 .16 - - 5 100000 - - - - .90 1.0 FJUIS��A �•� �Ii1 APR 9 199. U DEM PROJ W lLQgD� Data for CROSS SEED CO. 91015 Prepared by SITEWORKS DESIGN GROUP, P.A. 2 Apr 91 HydroCAO Release 2.51 (c) 1986-1990 Apvlied Microcomputer Systems REACH 1 to 9999 REACH ROUTING BY STOR-IND METHOD REACH BOTTOM SIDE PEAK CONTACT PEAK NO. DIAM WIDTH DEPTH SLOPES n LENGTH SLOPE VEL. TIME Qout (IN) (FT) (FT) (FT/FT) (FT) (FT/FT) (FPS) (SEC) (CFS) 1 - - 1.2 .33 .33 .020 510 .0050 2.8 185 5.1 2 - - 1.0 .33 .33 .013 115 .0280 7.6 15 6.6 3 - - 1.0 .33 .33 .020 210 .0050 :2.9 73 6.1 4 24.0 - - - - .013 30 .0050 2.0 15 .1 5 36.0 - - - - .013 110 .0136 11.0 10 35.1 6 36;0 - - - - .013 105 .0136 11.0 10 35.8 7 - - 1.0 .33 .33 .020 340 .0050 1.7 197 .8 veloa'-h'es in bgrcwr A{ sweles, h=-Oz Data for CROSS SEED CO. 91015 Prepared by SITEWORKS DESIGN GROUP, P.A. 27 Mar 91 HydroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems REACH 1 to 9999 REACH ROUTING BY STOR-IND METHOD REACH BOTTOM SIDE PEAK CONTACT PEAK NO. DIAM WIDTH DEPTH SLOPES n LENGTH SLOPE VEL. TIME Qout (IN) (FT) (FT) (FT/FT) (FT) (FT/FT) (FPS) '(SEC) (CFS) 1 - - 1.2 .33 .33 .030 510 .0050 2.0 256 4.7 2 - - 1.0 .33 .33 .013 115 .0280 7.6 15 6.1 3 - - 1.0 .33 .33 .030 210 .0050 2.1 100 5.9 4 24.0 - - - - .013 30 .0050 2.0 15 .1 5 36.0 i - - - - .013 110 .0136 11.0 10 35.1 6 36.0 - - - - .013 105 .0136 11.0 10 35.8 Ve/aciii'es in 5awne� /ii��i�q 5u�a�es 7 =. o3 Data for CROSS SEED CO. 91015 Prepared by SITEWORKS DESIGN GROUP, P.A. 24 Mar 91 HydroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems POND 1 to 9999 POND ROUTING BY STOR-IND METHOD POND OUTLET SPECIAL START FLOOD PEAK PEAK Qpeak Qpeak Qpeak NO. DEVICES OUTLETS ELEV. ELEV. ELEV. STORAGE ATTEN. LAG OUT (FT) (FT) (FT) (AF) (o) (MIN) (CFS) 1 2 - 35.8 38.6 36.8 .22 99 21.1 .1 Data for CROSS SEED CO. 91015 Prepared by SITEWORKS DESIGN GROUP, P.A. 26 Mar 91 HydroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems POND 1 to 9999 POND 1 POND 1 STARTING ELEV= 35.8 FT FLOOD ELEV= 38.6 FT ELEVATION CON.AREA INC.STOR CUM.STOR (FT) (SF) (CF) (CF) 35.8 8888 0 0 37.2 10351 13454 13454 38.6 11882 15551 29005 STOR-IND METHOD PEAK ELEVATION= 36.8 FT PEAK STORAGE = 9366 CF Qin = 13.6 CFS @ 10.19 HRS Qout= .1 CFS @ 10.54 HRS ATTEN= 99 96 LAG= 21.1 MIN IN/OUT= .22 / .06 AF INVERT (FT) OUTLET DEVICES 35.8' 1.7" ORIFICE Q=.6 PI r^2 SQR(2g) SQR(H-r) 37.2 9' SHARP -CRESTED WEIR Q=C L H^1.5 C=3.27+.4 H/l L=Length-2(.1 H) TOTAL DISCHARGE vs ELEVATION FEET 0.0 .1 .2 .3 .4 .5 .6 .7 '.8 .9 35.8 0.0 0.0 0.0 0.0 0.0 0.0 .1 .1 .1 .1 36.8 .1 .1 .1 .1 .1 1.0 2.8 5.1 7.8 11.0 37.8 14.6 18.5 22.8 27.4 32.4 37.7 43.3 49.2 55.4 Data for CROSS SEED CO. 91015 Prepared by SITEWORKS DESIGN GROUP, P.A. 24 Mar 91 HydroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems POND 1 to 9999 POND 1 HOUR 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00 13 12 11 10 9 8 7 6 4 3 2 POND 1 INFLON & OUTFLOW POND 1 STOR—IND METHOD PERK ELEV= 36.9 FT PERK STOR= 9365 CF Qin= 13.6 CFS Qout= .1 CFS LAG= 21.1 MIN 0i CD V Ln CD r� TIME (hours) POND 1 OUTFLOW PEAK= .1 CFS @ 10.54 HOURS CC) Ol CD N 0.0 0.0 .1 .1 .1 .1 .1 .1 .1 .1 .1 ., 1 Data for CROSS SEED CO. 91015 FUTURE DEVELOPMENT Page 1 Prepared by SITEWORKS DESIGN GROUP, P.A. 26 Mar 91 HydroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems SUBCATCHMENT 1 to 9999 RUNOFF BY RATIONAL METHOD: DURATION= 10 MIN INTEN= 6.40 IN/HR SUBCAT AREA LEN SLOPE Tc WGT'D PEAK NUMBER (ACRE) (FT) (96) (MIN) --- GROUND COVERS (96CN) --- CN C (CFS) 1 1.00 - - 5 100 WO - - - - .90 5.9 2 .30 - - 16 100%00 - - - - .35 .3 3 .30 - - 7 1009600 - - - - .90 1.6 4 1.10 - - 10 100-%00 - - - - .90 5.2 5 .40 - - 11 1009600 - - - - .35 .7 6 .20 - - 4 1009600 - - - - .90 1.2 7 .30 - - 18 100-%00 - - - - .35 .3 8 5.00 - - 30 100.%00 - - - - .25 2.2 9 17.50 - - 22 100-%00 - - - - .50 21.0 10 2.50 - - 9 1009600 - - - - .85 11.3 11 1.10 - - 10 1009600 - - - - 1.90 5.2 n Ll ILIj��\l APR 9 JD_ EM PROF F� /0q0s- Data for CROSS SEED CO. 91015 FUTURE DEVELOPMENT Prepared by SITEWORKS DESIGN GROUP, P.A. 27 Mar 91 HydroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems REACH 1 to 9999 REACH ROUTING BY STOR-IND METHOD REACH BOTTOM SIDE PEAK CONTACT PEAK NO. DIAM WIDTH DEPTH SLOPES n LENGTH SLOPE VEL. TIME Qout (IN) (FT) (FT) (FT/FT) (FT) (FT/FT) (FPS) (SEC) (CFS) 1 - - 1.2 .33 .33 .030 510 .0050 2.1 239 6.4 2 - - 1.0 .33 .33 .013 115 .0280 8.1 14 8.2 3 - - 1.0 .33 .33 .030 210 .0050 2.2 95 7.9 4 24.0 - - - - .013 30 .0050 2.9 10 1.1 5 36.0 - - - - 013 110 .0136 11.6 9 46.6 6 36.0 - - - - .013 105 .0136 11.7 9 47.4 Data for CROSS SEED CO. 91015 FUTURE DEVELOPMENT Page 3 Prepared by SITEWORKS DESIGN GROUP, P.A. 26 Mar 91 PxidrnrAn Ralaaca 7 51 (r) 1QAFi-iaon Annlind lAirrnrnmmitar Cvctownc POND 1 to 9999 POND ROUTING BY STOR-IND METHOD POND OUTLET SPECIAL START FLOOD PEAK PEAK Qpeak Qpeak Qpeak NO. DEVICES OUTLETS ELEV. ELEV. ELEV. STORAGE ATTEN. LAG OUT (FT) (FT) (FT) (AF) (6) (MIN) (CFS) 1 2 - 35.6 38.2 36.9 .30 99 20.5 .1 Data for CROSS SEED CO. 91015 FUTURE DEVELOPMENT Prepared by SITEWORKS DESIGN GROUP, P.A. N\/rlrnrAn Roloaco 9 m (r) laAA-loon Annliorl Mirr POND 1 to 9999 POND 1 POND 1 STARTING ELEV= 35.6 FT FLOOD ELEV= 38.2 FT ELEVATION CON.AREA INC.STOR CUM.STOR (FT) (SF) (CF) (CF) 35.6 9032 0 0 37.2 10714 15778 15778 38.2 11844 11274 27052 Page 4 26 Mar 91 STOR-IND METHOD PEAK ELEVATION= 36.9 FT PEAK STORAGE = 12984 CF Qin = 18.8 CFS @ 10.18 HRS Qout= .1 CFS @ 10.52 HRS ATTEN= 99 96 LAG= 20.5 MIN IN/OUT= .30 / .07 AF INVERT (FT) OUTLET DEVICES 35.6 1.8" ORIFICE Q=.6 PI r^2 SQR(2g) SQR(H-r) 37.2 9' SHARP -CRESTED WEIR Q=C L H^1.5 C=3.27+.4 H/l L=Length-2(.1 H) TOTAL DISCHARGE vs ELEVATION FEET 0.0 .1 .2 .3 .4 .5 .6 .7 .8 .9 35.6 0.0 0.0 0.0 0.0 0.0 .1 .1 .1 .1 .1 36.6 .1 .1 .1 .1 .1 .1 .1 1.0 2.8 5.1 37.6 7.9 11.0 14.6 18.5 22.8 27.5 32.4 37.7 Data for CROSS SEED CO. 91015 FUTURE DEVELOPMENT Prepared by SITEWORKS DESIGN GROUP, P.A. 27 Mar 91 HvdroCAD Release 2.51 (c) 1986-1990 Applied Microcomputer Systems POND i to 9999 POND 1 POND 1 STARTING ELEV= 35.6 FT FLOOD ELEV= 38.2 FT ELEVATION CON.AREA INC.STOR CUM.STOR (FT) (SF) (CF) (CF) 35.6 9032 0 0 37.2 10714 15776 15778 38.2 11844 11274 27052 STOR-IND METHOD PEAK ELEVATION= 37.3 FT PEAK STORAGE = 16997 CF Qin = 25.1 CFS @ 10.18 HRS Qout= 1.2 CFS @ 10.43 HRS ATTEN= 95 96 LAG= 14.6 MIN IN/OUT= .40 / .11 AF INVERT (FT) OUTLET DEVICES 35.6 1.8" ORIFICE Q=.6 PI r^2 SQR(2g) SQR(H-r) 37.2 9' SHARP -CRESTED WEIR Q=C L H^1.5 C=3.27+.4 H/1 L=Length-2(.1 H) TOTAL DISCHARGE vs ELEVATION FEET 0.0 .1 .2 .3 .4 .5 .6 .7 .8 .9 35.6 0.0 0.0 0.0 0.0 0.0 .1 .1 .1 .1 .1 36.6 I .1 .1 .1 .1 .1 .1 .1 1.0 2.8 5.1 37.6 7.9 11.0 14.6 18.5 22.8 27.5 32.4 37.7 ,E ` JOB re; ! __C?• SITEWORKS DESIGN GROUP SHEET NO. ' OF P.O. Box 3988 CALCULATED BY �12Lf DATE 3-27 9r WILMINGTON, NORTH CAROLINA 28406 (919) 799-6808 CHECKED BY DATE SCALE RIOOIICI7a1�4s,OMIn.Wp. %IIl, topaz M1gNETOLLiPEF FIOPtlSNEO SITEWORKS DESIGN GROUP P.O. Box 3988 WILMINGTON, NORTH CAROLINA 28406 (919) 799-6808 D ADD SHEET NO. `� OF CALCULATED BY 14•j' L q DATE CHECKED BY DATE SCALE M 4oRii X J� 7S61�wa Mal. ie�M Tmntm IJmOSdeE J0B �,v;sCo. 91 DI SITEWORKS DESIGN GROUP SHEET NO. /]� OF P.O. Box 3988 CALCULATED BV A 2l_ —DATE -�-ZS - 9� WILMINGTON, NORTH CAROLINA 28406 (919) 799.6808 CHECKED BY DATE SCALE Ri0d101 �I�F[.b�bIYm Mal. T. �R TOIL BEE 1i JOB SITEWORKS DESIGN GROUP SHEET NO. OF P.O. Box 3988 CALCULATED BY DATE WILMINGTON, NORTH CAROLINA 28406 (919) 799-6808 CHECKED BY DATE Baou-,�i�nc.0iaimm pni.r.aa.ngx[ POLL mB,amm SITEWORKS DESIGN GROUP P.O. Box 3988 WILMINGTON, NORTH CAROLINA 28406 (919) 799-6808 P11 TmlclmWNt,d .W 01471. Tc4 "MTOLLIPF£IA}Yd61E0 JOB (7ro f, S . 4-- <N SHEET NO. p5 OF �I CALCULATEDBV , pa— DATE 9' CHECKED BY DATE SCALE OPERATION & MAINTENANCE MANUAL Cross Seed Company Site Project #91015 1. Description The Stormwater detention system consists of a detention pond, and regulated outflow device. The pond is approximately 10000 square feet in area and 4.5 feet deep at the normal water level, and will be graded at 3:1 and protected by aquatic vegetation. Outflow from the pond is regulated by a concrete outlet structure. The regulating device is a 1-3/4" orifice in one side of the concrete box at the normal pool level of 35.8. This opening allows the 1" runoff volume to escape the pond in 2 days. 2. Operation The purpose of the stormwater detention system is to collect and store the runoff from the first inch of rainfall on the site, allow sediment to settle out of the runoff and discharge the stored water over a 2 to 5 day period The methods by which this occur do not require operator attention, other than maintenance requirements. Stormwater runoff flows by gravity to the pond. For rainfalls of 1" or less the pond will rise up to 1.4 feet and drop back down over a 2 to 5 day period as water discharges through the 1-3/4" diameter hole. For.rainfalls greater than 1", once the water level rises by 1', it will flow over the weirs around the concrete box, and discharge thru a 24" RCP from the system. All stormwater receives some degree of settling and treatment, but the rainfall in excess of 1" discharges much sooner. ECEIVED 4PR 9 19G. D.EM kROJ � `iio o�� 3. Maintenance Routine maintenance will be required to keep the pond operating as designed. Each runoff producing rain: 1. Check orifice and concrete box and remove any trash. 2. Check areas around swales for erosion. Make repairs promptly. Weekly: .1. Remove trash from pond slopes. Quarterly: 1. Pond depth should be measured to check sediment levels. Normal depth is 4.5 feet. Sediment removal'is.necessary when depth is 3.5 feet. Sediment should be removed with a backhoe, being careful no to damage the pond slopes. 2. Check grassed areas around pond for erosion. Repairs should be made promptly. 4. Responsibility Cross Seed Company, owner will be responsible for routine maintenance of the system, and the complete restoration of any failed, damaged or deteriorated components. I, Tom Nunilee, have read and understand the intent of this document. Signature ° a'��`7i Date APR n NS, D.EM PRoJ _._.-o qos