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HomeMy WebLinkAboutSW8881202_Historical File_19890125 „mod SrA State of North Carolina • Department of Natural Resources and Community Development Wilmington Regional Office James G. Martin, Governor Bob Jamieson William W. Cobey, Jr., Secretary Regional Manager DIVISION OF ENVIRONMENTAL MANAGEMENT January 25, 1989 Mr. Joseph S. Hill, Jr. , P.E. Joseph S. Hill, Jr. and Associates P.O. Box 5592-STA 1 Wilmington, NC 28403-4155 Subject: Determination of Compliance with Stormwater Regulations Project # 881202 Oak Brook III Subdivision & Brick Landing Brunswick County Dear Mr. Hill: The Wilmington Regional Office received the Stormwater Management submittal for the subject project on December 1, 1988. Based on our review of the project documents, we have determined that the project complies with the Stormwater Regulations set forth in Title 15 NCAC 2H.1003 (g) ( 2 ) . If you have any questions concerning this matter, please contact Mark Hawes or me at ( 919) 256-4161. .Sincerely, Origin 0 Sim fy 4. PRESTON HOWARD, A. Preston Howard, Jr. , P.E. Regional Supervisor APH:MH:cwc cc: Bill Mills WiRO, CF 7225 Wrightsville Avenue, Wilmington. N.C. 28403-3696 °Telephone 919-256-4161 An Equal Opportunity Affirmative Action Employer DIVISION OF ENVIRONMENTAL MANAGEMENT Evaluation of Stormwater Treatment and Disposal System Draining to Waters Other Than Class SA PROJECT DATA Project Name: Oak Brook III Subdivision Project No. 881202 Brick Landing Plantation Location (County, Township/Municipality, Address) : Brunswick County Applicant Name: Joseph S. Hill, Jr. , P.E. Mailing Address: Joseph S. Hill, Jr. , and Associates P.O. Box 5592-STA 1 Wilmington, NC , 28403-5592 Submittal Date: December 1, 1988 Water Body Receiving Stormwater Runoff: Unnamed tributary to Goose Creek (C-SW) Name of Water Body: Classification of Water Body: C-Swamp WET DETENTION POND 1. C' a 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. es No The permanent pool is designed for 85% TSS removal. 3. es No The runoff completely draws down to the permanent pool in 5 days, but not less than 2 days. 4. No The mean depth of the permanent pool is a minimum of 3 feet. 5. es) No The inlet structure is designed to minimize turbulence and short circuiting. 6. Yes_. No All overflow and discharge flows through a vegetative filter at least 10 feet in length. 7 . es No A method is used to provide even distribution of runoff over the length of the vegetative filter. 8. gf5P No The slope and width of the vegetative filter provides non-erosive flow for the 10-year 24-hr storm with a 10-yr, 1-hr intensity. 9. 6) No The vegetative filter has a slope of 5% or less. 10. til, No The vegetative filter is natural, grassed or artificially planted wetland vegetation. 11. (41, No An appropriate operation and maintenance plan has been provided for the system. 12. es No THIS PROJECT MEETS THE STORMWATER CONTROL REQUIREMENTS OF 15 NCAC 2H. (g) , ( i) , ( j ) , (k) , and (1) (For yes, 1 through 11 must all be circled yes) . Brief Explanation: The Operation and Maintenance Plan is located on Pg 2 of 2 on Plans. DIVISION OF ENVIRONMENTAL MANAGEMENT SIGN-OFF Wilming on Regional Office ,2 5 n.,_ Mq -L1940.4_ . -- A at t 444-- Date valuating Form/Plans L Original Signed By Datq)(i o S' x- /919 A. PRESTON HOWARD, JR Regional Water Quality Supervisor cc: Applicant/WiRO/Mills/CF ([? 7�d ,i mil .-�/ 1 �r �_\ Le%I A!1 January 11, 1989 Mr. Mark Hawes N.C. Division of Environmental Management 7225 Wrightsville Avenue Wilmington, North Carolina 28403 Subject: Oakbrook III Brick Landing Plantation Stormwater Management Plan Restrictive Covenants Limiting "Built-Upon" Surfaces Brunswick County Dear Mr. Hawes: The following statement will be included in the Restrictive Covenants for Oakbrook III Subdivision: "No more than 2,500 square feet of any lot shall be covered by structures and/or paved surfaces, including walkways or patios of brick, stone, slate or similar mater- ials. This covenant is intended to insure continued compliance with Stormwater runoff rules adopted by the State of North Carolina and therefore benefits may be enforced by the State of North Carolina." The following will be stated in the deed: "This (these) covenant(s) is (are) to run with the land and shall be binding on all parties and all persons claiming under them." SIGNATURE Signature e ° _..� Date / - -177 VERIFICATION (Typed or Printed Name) H. z 6AL personally appearing before me and, being first duly sworn, says that the information contained in this application and in the exhibits attached hereto are true to the best of his/her knowledge and beliefs. This c20 7* day of �/W(4 4RA/ , 1989 Notary PullIs4,,,,,,4„04 // - Address U cc: JSH, Jr. and Assoc. My Commission ExpiresD to/2 z 92. Date Ocean Isle Beach, North Carolina 28459 919-754-4373 Inside NC 1-800-222-9938 Outside NC 1-800-438-3006 RECEIVED JAN 'z b 1Y. Wilmington Regional Office nFM Prepared by: MURCHISON, TAYLOR, KENDRICK, GIBSON & DAVENPORT 16 North Fifth Avenue, Wilmington, NC 28401 SUPPLEMENTAL DECLARATION OF STATE OF NORTH CAROLINA COVENANTS, CONDITIONS AND RESTRICTIONS OF OAKBROOK AT COUNTY OF BRUNSWICK BRICK LANDING PLANTATION, PHASE III THIS SUPPLEMENTAL DECLARATION, made the day of , 1989, by Bricklanding Associates Limited Partnership, a Virginia Limited Partnership with its principal place of business in Brunswick County, North Carolina, (Declarant ) ; WITNESSET H: WHEREAS, Declarant is the owner of certain real property in Brunswick County, North Carolina (hereinafter referred to as the "Property" ) which is more particularly described as follows : BEING all of Oakbrook At Brick Landing Plantation, Phase III (herein called "Oakbrook III" ) , as the same is shown on the plat thereof recorded in Map Book T at Pages 159 and 160 in the Office of the Register of Deeds of Brunswick County, North Carolina, to which plat reference is hereby made for a more particular description. AND, WHEREAS, Declarant has heretofore executed Declaration of Covenants, Conditions and Restrictions of Oakbrook at Brick Landing Plantation, Phase III; said Declaration has been recorded in the Office of the Register of Deeds of Brunswick County, North Carolina; Declarant is exercising the powers and duties of the Association pursuant to Article V, Section 1 of the Declaration; and Declarant is herewith supplementing the covenants, conditions and restrictions of the Declaration; NOW, THEREFORE, Declarant hereby declares that all of the Property described above, and any property which may here- after be made subject to this Supplemental Declaration, shall be held, sold and conveyed subject to the following additional easements, restrictions , covenants and conditions, which are for the purpose of complying with applicable laws and regulations, insuring the use of the Property for attractive residential purposes only, preventing nuisances to the property, maintaining the desired tone of the subdivision community, and thereby securing to each property owner the full benefit and enjoyment of his property with no greater restriction upon the free and undisturbed use of his property than is necessary and to insure the same advantages to other property owners . 1 . No more than 2500 square feet of any Lot shall be covered by structures and/or paved surfaces, including walkways and patios of brick, stone, slate or similar materials . This covenant is intended to insure continued compliance with storm water runoff rules adopted by the State of North Carolina, and therefore the benefits of this Supplemental Declaration may be enforced by the State of North Carolina. IN WITNESS WHEREOF, the Declarant has caused this Supplemental Declaration to be executed, as of the day and year first above written . BRICKLANDING ASSOCIATES LIMITED PARTNERSHIP, a Virginia Limited Partnership BY: Gd (SEAL) General Partner NORTH CAROLINA BRUNSWICK COUNTY I, a Notary Public in an for the State and county aforesaid, do certify that , general partner of Bricklanding Associates Limited Partnership, a Virginia Limited Partnership, personally appeared before me this day and acknowledged the due execution of the foregoing instrument. WITNESS my hand and official seal this a..y't-Z. day of �xn , 1989 . No ary Public My commission expires: 6 -2-2- - 9 2 JOSEPH S. HILL, JR. and ASSOCIATES CONSULTING ENGINEERS and PLANNERS MAILING ADDRESS: 1602 HARBOUR DRIVE POST OFFICE BOX 5592-STA.1 WILMINiGTON,NORTH CAROLINA WILMINGTON,N.C.28403-4155 TELEPHONE 919-799-1544 RECEIVED January 23, 1989 "BAN 2 4 i989 Wilmington Reional coo Mr. Mark Hawes N.C. Division of Environmental Management 7225 Wrightsville Avenue Wilmington, North Carolina 284Q3 Subject: Oakbrook III Subdivision Brick Landing Plantation Stormwater Management Plan Brunswick County Dear Mr. Hares: Attached is the signed Statement of Re.sponstbAlity for Oakbrook. III at Brick Landing Plantation Stormwater Management Plan. Also attached is the notorized statement regarding the restrictive covenants limiting the "built-upon" area for each lot. Please include these statement in the Oakbrook. III Stormwater Management Plan. Please do not hesitate to contact me if you have any questions. Sincerely, JOSEPH S. KILL, JR. and ASSOCIATES Josep S. Uill , Jr. , P.E. JSH/pva Grayarc• P.O.Box2944 REPLY MESSAGE Hartford,CT 08104.2944 CALL TOLL FREE:1.800.243.5250 Fold At(4)To Fit Grayarc Window Envelope N EW1OP REORDER ITEM N - - - ——-- —— --—--- __-_- FROM F r -1 MURCHISON, TAYLOR,' KENDRICK, TO MR, MARK HAWES GIBSON & DAVENPORT P.O. Box 1270 SHALLOTTE, NORTH CAROLINA 28459 SUBJECT: SUPPLEMENTAL DECLARATION BOLD 4 ENCLOSED PLEASE FIND A SIGNED COPY OF THE SUPPLEMENTAL DECLARATION OF OAKBROOK III AT BRICK LANDING PLANTATION. PLEASE CONTACT OUR OFFICE IF YOU HAVE ANY QUESTIONS REGARDING THIS MATTER. c—t .-A PLEASE REPLY TO SIGNEDAALI-60 v<( REPLY JOSEPH S. HU L, JR. and ASSOCIATES CONSULTING ENGINEERS and PLANNERS MAILING ADDRESS: 1602 HARBOUR DRIVE POST OFFICE BOX 5592-STA.1 WILMINGTON,NORTH CAROLINA WILMINGTON,N.C.28403-4155 TELEPHONE 919-799-1544 RECEIVED January 19, 1989 JAN 2 01989 WI1mj — . ON D J � Mr. Mark Hawes D N.C. Division of Environmental Management 7225 Wrightsville Avenue �\\ JAN 2 3 19$9 Wilmington, North Carolina 28403 „13.o ESS DIEM Subject: Oakbrook III Stormwater Plan I # Orifice Size Revision Stormwater Detention Pond #3 Brick Landing Plantation Brunswick County Dear Mr. Hawes: Attached are two (2) copies of the Oakbrook III Stormwater Management Plan, Sheet #1 . The orifice size for the Pond #3 outlet structure is correctly shown to be l" in diameter, rather than 1/2" in diameter as shown on the originally submitted plan (see Outlet Structure Detail - Detention Pond #3). Please do not hesitate to contact me if you have any questions. or need additional information. Sincerely, JOSEPH. S. RILL, JR. and ASSOCIATES 411, 4 e5 delaq. Josh. S. Hill, Jr. , P.E. JSH/pva attachments --VW:T-2/1QA,t14-4- r� /S N/99 C��JXxc/k 2 i20.Z. 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Page 1 /b /Fc AJ w- E os/1/E FLOW fOR � � .2 VARIABLE SHEET St Input Name Output Unit Comment 28.38 Q FT-3/SEC PEAK FLOW RATE V 2.4685570 FT/SEC CHANNEL VELOCITY A 11 .496595 FT-2 AREA OF FLOW 1 .5 B FT BOTTOM WIDTH OF CHANNEL D 2.0517102 FT DEPTH OF FLOW 2 Z SIDE SLOPE RATIO Wp 10.675527 FT WETTED PERIMETER Rh 1.0769112 FT HYDRAULIC RADIUS .001 S SLOPE .02 n ROUGHNESS COEFF. Page 1 /® YX NoA( ERGS AM' ,LaW rog VARIABLE SHEET POA/® $3 St Input Name Output Unit Comment 6.03 Q FT-3/SEC PEAK FLOW RATE V 1 .6650899 FT/SEC CHANNEL VELOCITY A . 3 .6214260 FT-2 AREA OF FLOW 1.5 B FT BOTTOM WIDTH OF CHANNEL D 1.021903 FT DEPTH OF FLOW 2 Z SIDE SLOPE RATIO Wp 6.0700891 FT WETTED PERIMETER Rh .59660178 FT HYDRAULIC RADIUS .001 S SLOPE . 02 n ROUGHNESS COEFF. Page 1 JOSEPH S. HILL, JR. and ASSOCIATES CONSULTING ENGINEERS and PLANNERS MAILING ADDRESS: 1602 HARBOUR DRIVE POST OFFICE BOX 5592-STA.1 WILMINGTON,NORTH CAROLINA WIi.MINGTON,N.C.28403.4155 . TELEPHONE 919-799-1544 January 11 , 1989 Uj a s'�—.yN 1 7 1989 Mr. Mark Hawes �r N.C. Division of Environmental Management DIE: ha 7225 Wrightsville Avenue Wilmington, North Carolina 28403 Subject: Project No. 881202 Resubmittal of Stormwater Management Plan Oakbrook III Subdivision. Brick Landing Plantation Brunswick County Dear Mr. Hawes:. Attached are two (2) copies each. of the revised Stormwater Management Plan, Swale Seeding Specifications, and calculations for Oakbrook III Subdivision at Brick Landing Plantation. The following items are included in response to your.December 19, 1988 letter: 1 . Plan and profile drawings of the collection and disposal systems. 2. Runoff volume, detention capacity, and dewatering time calculations. 3. Cross-section of pond and swale including length of vegetative filter strips. 4. Drainage patterns for the design storm and drainage patterns for runoff in excess of design storm are identical except for the flow path through the detention pond outlet structures. Pond outlet pipes and swales are designed to transmit flows from a, 1.00year storm event at nonerosive velocities. 5. Stormwater control system operation and management procedures are shown on the plans. We have requested Mr. H. Michael Brazeal to sign and submit to you a Statement of Responsibility for ownership and operation of the stormwater ' management system. The statement names Brick Landing Plantation Homeowner's Association as the responsible party. Mr. Brazeal has also been requested to send you a signed and notorized statement that a Restrictive Covenant will limit the amount of "built-upon" surfaces covering any lot to 2,500 square feet and that the restrictions will run with the deed. 6 . J, N 1 7 1989 Mr. Mark Hawes Oakbrook III 'di January 11 , 1989 # 881 Zoz Page 2 A copy of each of the unsigned statements is included for you reference. Please. do not hesitate to contact me or Mike.. Marsh if you have any questions or need additional information. Sincerely, JOSE.PR S. EIILL, JR-. and ASSOCIATES , , �. . Jo'eph S. Hill , Jr., P.E. JSH/pva attachments JOSEPH S. HILL, JR. and ASSOCIATES CONSULTING ENGINEERS and PLANNERS MAILING ADDRESS: 1602 HARBOUR DRIVE POST OFFICE BOX 5592-STA.] WILMINGTON,NORTH CAROLINA WILMINGTON,N.C.28403-4155 TELEPHONE 919-799.1544 January Tl 1989 ,11V , L 'iJ Rjj JAN 1 7 1989 Mr. R. Michael Brazeal U ila Project Director -run # 8$IZOZ. Brick Landing Plantation Rt. 2, Box 210 Ocean Isle Beach, N.C. 28459 Subject: Oakbrook IIT Stormwater Management Plan Statement of Responsibility Restrictive Covenants Dear Mr. Brazeal : Attached is a Statement of Responsibility for the Oakbrook III at Brick Landing Plantation Stormwater ManagementSystem. This statement is required for approval of the stormwater management plan submitted to the N.C. Division of Environmental Management. Also attached is a letter stating that the restrictive covenants and deed will be written to include compliance provisions with. the Stormwater Management Plan. This restriction required that the "Built- upon" surface area of any lot shall not exceed 2,500 square feet in accordance with the design calculations. Please have both statements typed on your- letterhead and sign the Statement of Responsibility. The letter pertaining to the restrictive covenants should be signed and notarized. Please send these to us so that we may submit them to DEM. Please do not hesitate to call me if you have any questions. Sincerely, JOSEPH S. HILL, JR. and ASSOCIATES ill 1411 Josep . S. Hill , Jr. , P.E. JSH/pva cc: Mr. Mark Hawes BRICK LANDING PLANTATION Rt. 2, Box 210 Ocean Isle Beach, North Carolina 28459 January 11 , 1989 Mr. Mark Hawes N.C. Division of Environmental Management 7225 Wrightsville Avenue Wilmington, North Carolina 28403 Subject: Oakbrook III Brick Landing Plantation Stormwater Management Plan Restrictive Covenants Limiting "Built-Upon" Surfaces Brunswick County Dear Mr. Hawes: The following statement will be included in the Restrictive Covenants for Oakbrook III Subdivision; "No more than 2,500 square feet of any lot shall be covered by structures and/or paved surfaces, including walkways or patios of brick, stone, slate or similar materials. This covenant is intended to insure continued compliance with stormwater runoff rules adopted by the State of North Carolina and therefore benefits may be enforced by the State of North. Carolina:" The following will be stated in the deed: "This (these) covenant(s) is (are) to run with the land and shall be binding on all parties and all persons claiming under them. " SIGNATURE Signature Date VERIFICATION (Typed or Printed Name) personally appearing before me and, being first duly sworn, says that the information contained in this application and in the exhibits attached hereto are true to the best of his/her knowledge and beliefs. This day of , 1989 Notary Public Address cc: JSH, Jr. and Assoc. My Commission Expires Date BRICK LANDING PLANTATION Rt. 2, Box 210 Ocean Isle Beach, North Carolina 28459 January 11 , 1989 Mr. Mark Hawes N.C. Division of Environmental Management 7225 Wrightsville Avenue Wilmington, North Carolina 28403 Subject: Statement of Responsibility Stormwater System Operation and Maintenance Oakbrook III at Brick Landing Plantation Brunswick County Dear Mr. Hawes: This letter acknowledges that a Stormwater Management Plan has been submitted on behalf of Oakbrook III at Brick Landing Plantation. Brick Landing Plantation Homeowner's Association will be responsible for the operation and maintenance of the system as required by DEM and the operation and maintenance procedures included as an integral part of the Stormwater Management Plan. Brick Landing Plantation Homeowner's Association will be responsible for repairing or replacing any part of the stormwater management system which may become inoperable. Sincerely, H. Michael Brazeal Project Director cc: Joseph S. Hill , Jr. and Assoc. [)) L. o L L, SECTION 1600 - LANDSCAPING - EROSION and SEDIMENT 1p6TROL ,J a:N i e i989 A. General .#-.$ IZOz. The Contractor shall provide all labor, materials, equipment, tools, and perform all work and services necessary for or incidental to landscaping as required by these specifications and/or shown on the plans. All supplementary or miscellaneous items, appurtenances or services necessary for a complete job shall be furnished as- a part of this work, although such work shall not necessarily be shown or specified. All work shall comply with the regulations of the North. Carolina Sedimentation Control Act of 1973.. All erosion control devices_ shall be installed and maintained as required by the North. Carolina Department of Natural Resources and Community Development. Such measures may consist of berms, dikes, drains, and sediment basins, or use of fiber mats, woven plastic filter cloths., gravel , mulches, bituminous spray, and other erosion control devices or methods. All erosion and sediment control devices shall be approved by the Engineer prior to installation. B. Landscaping 1 . The work. includes seedbed preparation, liming, fertilizing, seeding, and mulching of all disturbed areas. The work also includes those areas inside or outside of limits of construction that are disturbed by the Contractor's operation, 2. The ground surface shall be clear of stumps, stones, roots, cables, wire, grade stakes, and other materials that might hinder proper grading, tillage, seeding or subsequent maintenance operations. 3. Where lawns are to be planted in areas that have not been altered or disturbed by excavating, grading, or stripping operations, prepare soil for lawn planting as follows: Till to a depth of not less than 6". Apply soil amendments and initial fertilizers as specified. Remove high areas and fill in depressions. Till soil to a homogenous mixture of fine texture, free of lumps, clods, stones, roots, and other extraneous matter. 4. Grades on the area to be seeded shall be maintained to a true and even condition. Maintenance shall include any necessary repairs to previously graded areas. 5. All graded areas shall be thoroughly tilled to a deptb. of at least four (4) inches by plowing, disking, harrowing, or other approved methods until the condition of the soil is acceptable. On sites where soil conditions are such that high. clay content and excessive compaction cause difficulty in getting clods and lumps effectively pulverized, the Contractor shall use the rotary tillage machinery, until the mixing of the soil is: acceptable and no clods and clumps remain larger than 1 1/2 inches in diameter. A firm and compact seedbed is required, and after being graded, the. seedbed shall be lightly compacted with a land roller such as a cultipacker before and after seeding. 6. Limestone shall be dolomitic agricultural-ground limestone containing not less than 10 percent magnesium oxide and uniformly applied at a rate of 2000 pounds per acre prior to preparation of seedbed. 7. Fertilizer shall be the standard commercial product uniformly applied at a rate of 1000 pounds per acre-of 10.-10-1Q' analysis_ 8. The fertilizer shall be incorporated into the upper three or • four inches of prepared seedbed just prior to the last tillage operation, but in no case shall be applied more than three days prior to seeding. Fertilizer shall be used immediately after delivery or. stored in a manner that will not permit. it to harden or destroy its effectiveness. When. hydroseeding equipment is used for seeding, fertilizer shall be applied simultane.ouly with seed, using the above rates of application. 9. Seed shall be certified seed, or. equivalent based on North Carolina Seed Improvement Association requirements for certification. All seed shall be furnished in sealed standard containers. Seed which has become wet, moldy, or otherwise damaged prigr .to seeding, will not be acceptable. 10. Seeding shall be accomplished with. power-drawn planters and land packer or hydroseeding equipment at the rate of: From September 15 to April 15; 75 pounds per acre.Qf Tall Fescue, Kentucky 31 or Alta Tall Fescue, 100 pounds per acre Unhulled Bermuda, From April 15 to September 15: 75 pounds per acre of Hulled Bermuda. 75 pounds per acre. of Tall Fescue, Kentucky 31 , or Tall Fescue. l% maximum weed seed content permitted. 11 . When conditions are such_ by reason of drought, high_ winds, excessive moisture or other. factors where satisfactory results will not be obtained, the work shall be stopped and resumed only when conditions are favorable. 12. Mulching where required by the Engineer shall be dry grain straw or approved equal evenly applied at the rate of 40 bales per acre. 13. Method used to apply the mulch shall be mechanical type equipment and shall obtain a uniform distribution to permit sunlight to penetrate to the ground surface. 14. Provide and maintain temporary piping, hoses, and lawn watering equipment as required to convey water from water sources and to keep lawn areas uniformly moist as required for proper growth. Maintain lawns by watering, fertilizing, weeding, mowing, trimming, and other operations such as rolling regrading, replanting as required to establish a smooth, acceptable lawn, free of eroded or bare areas. Remulch with new mulch in areas where mulch has been disturbed by wind or maintenance operations sufficiently to nullify its purpose. Anchor as required to prevent displacement. Replace bare areas using same materials specified for lawns. \A/ ►7D OAKBROOK III l k �,� L G t 1= Stormwater Calculations BAN 1 7 1989 ivi -°RoI # 88►20z. Stormwater runoff from the project will be retained in 3 wet detention ponds. These ponds will .retain 1 inch of runoff from all surfaces in the watershed and discharge the retained runoff in approximately 5 days. The rate of discharge from each pond will be controlled by a specially designed stormwater control riser with an easily maintainable orifice discharge device. The surface area required for each pond to remove 85% of total suspended solids was calculated using SA/DA Percentage Chart (See Chart) for North. Carolina coastal regions. All outfall pipes and swales used as vegetative filters are designed to transmit flows generated by a 100-year storm at nonerosive velocities. _ 94;76es RUNOFF CALUCALATIONS - AREA #1 �-1 RoTFc i r�e` `6"�)S Q�O 32 Impervious Surfaces: 3SP"‘ 23 lots (2,500 Sq. Ft. Each) = 57,500 Sq. Ft. Streets = 32,450 Sq. Ft. Off Site (4 mobile homes 2 houses) = 7,000 Sq. Ft. Total Impervious Area = 96,950 Sq. Ft. Pervious Surfaces: Project lawns, street shoulders, etc.= 294,200 Sq. Ft. Off Site Impervious Area = 120,000 Sq. Ft. Total Pervious Area = 414,200 Sq. Ft. 96,950 Sq. Ft. (Impervious) .x .083' (1" Precipitation) = 8,047 CF Runoff 414,200 Sq. Ft. (Pervious) x .083' x 0.2 (Runoff Coefficient) = 6,876 CF Runoff Total Runoff= 14,923 CF Runoff (or 111 ,923 Gal . ) DETENTION POND #1 CALCULATIONS Minimum Pond Surface Area: 9.6,950 Sq. Ft. (Impervious) = 511 ,150 (Total Areal = 19% Impervious Area SA/DA % (_See Chart) for 85% TSS Removal @ 4' Pond Depth = 1 .2% Total Drainage Area = 511 ,150 = 11 ,73 AC 1 .2% x 11 .73 AC = 0.14 AC Required Pond Surface Area Pond #1 Area = 0.30 AC and is there adequate Stormwater Storage Depth; 14,923 CF (Runoff) t 13,06.E Sq, Ft. (Pond Area = 1 ,2' Storage Depth. Required ORIFICE DISCHARGE RATE CALCULATIONS - POND #1 Use 1 .5" diameter orifice for Pond #1 outlet. Calculate average discharge rate and time to lower orifice head from 1 .20' to 1 .10' : 0.10' pond height x 13,068 Sq. Ft. pond area x 7.5 gal/ft3 = 9800 Gal . Storage Average head on orifice from 1 .20' to 1 .10' = 1 .15' Average discharge rate @ 1 .15' Head: Q(GPM) = (449)c A 4'5 Q(GPM) = Volume discharged in gallons per minute c = discharge coefficient = 0.6 A = orifice area in square feet g = gravity = 32.2 h = head above center of orifice Q(GPM) =(449)(.6)(.0122) V(2)(32.2)(1 .15) Q = 28 GPM Time required to lower pond 0.1 ' @ 1 .15' average head: T = 9,800 Gal . = 28 GPM = 350 minutes 28 GPM vs 350 minutes plotted on curve (See Discharge Curve) . Discharge rate and time to lower head from 1 .10' to 1 .00.' : Q = 27 GPM T = 9,800 Gal . + 27 GPM = 362 minutes 27 GPM vs 712 minutes plotted on curve. Discharge rate and time to lower head from 1 .00' to 0.90' : Q = 26 GPM T = 9,800 Gal . = 26 GPM = 376 minutes 26 GPM vs 1088 minutes plotted on curve. Discharge rate and time to lower head from 0.90' to 0.80' : Q = 24 GPM T = 9,800 Gal . = 24 GPM = 408 minutes 24 GPM vs 1496 minutes plotted on curve. Discharge rate and time to lower head from 0.80' to 0.70' : Q = 23 GPM T = 9,800 Gal . j 23 GPM = 426 minutes 23 GPM vs 1922 minutes plotted on curve Discharge rate and time to lower head from 0.70' to D_6n' : Q = 21 GPM T = 9,800 = 21 466 minutes 21 GPM vs 2388 minutes plotted on curve. Discharge rate and time to lower head from 0.60.' to 0.50' ; Q = 19 GPM T = 9,800 = 19 = 515 minutes 19 GPM vs 2903 minutes plotted on curve. Discharge rate and time to lower head from Q.50.' to 0.40' : Q = 18 GPM T = 9,800 Gal . = 18 GPM = 544 minutes 18 GPM vs 3447 minutes plotted on curve. Discharge rate and time to lower head from 0.40' to 0.30' : Q = 16 GPM T = 9,800 Gal . = 16 GPM = 612 minutes 16 GPM vs 4059 minutes plotted on curve. Discharge rate and time to lower head from 0.30' to 0.20' : Q = 13 GPM T = 9,800 Gal . = 13 GPM = 753 minutes 13 GPM vs 4,812 minutes plotted on curve. Discharge rate and time to lower head from 0.20' to 0.10' : Q = 10 GPM T = 9,800 Gal . y 10 GPM = 980 minutes 10 GPM vs 5,792 minutes plotted on curve Discharge rate and time to lower head from 0.10' to 0.00' : Q = 6 GPM T = 9,800 Gal . = 6 GPM = 1633 minutes 6 GPM vs 7,425 minutes plotted on curve The outlet structure will discharge the total calculated runoff volume of 111,923 gallons in approximately 4 days (See Orifice Discharge Curve). A ►SCR R&5 Rj TE CEPM) 0 o ivo I I , tu N 4LIccat4ar:,� ' _ a o i I ! V N 3 � 39 0 "-N- Z - 2. Al coNs %7a I . 0 VI Z zdi 4.p..o 44 NQ 3r u, w •'NNo a-, IDc g o 0 7 0, 1 c9 V. ',3i r-- cz I hi 3 ° w z ° x, fl4A A -.; v — m -� � Xs Ins:: _ -t - 0 1 4, -4yq a ; " z -i aµ'+ 3 .4 as o I---1...1. Cil 1.4.0 b AI C1CN: ' + 4 11 tr 20 =1�0 = aka ti o+ 0 /... CI,.O ,� !at 0 �-0 �O Q © 11/41 e NI )/ O o 1- o ii -ts -t — o - / O % +� r` 0 / ` / N 1 \ '.' ..- 4A r- T L AREA 98, 8cO 7 S4, 7Z? RUNOFF CALCULATIONS - AREA #2 !_ 8 r�"L Impervious Surfaces: 73 Lots (2,500 Sq. Ft. Each) = 182,500 Sq. Ft. Streets = 98,800 Sq. Ft. Off Site (2 houses + 860 LF+ , 8' wide paved cart path) = 11 ,000 Sq. Ft. Total Impervious Area = 292,300 Sq. Ft. Pervious Surfaces: Project Lawns, street shoulders, etc. = 756,727 Sq. Ft. Off Site (lawns, golf fairway) = 188,615 Sq. Ft. Total Pervious Area = 945,342 Sq. Ft. 292,300 Sq. Ft. (Impervious) x ..083' = 24,261 CF Runoff 945,342 Sq. Ft. (Pervious) x .083' x 0.2' = 15,693 CF Runoff Total Runoff = 39,954 CF (299,655 Gal . ) DETENTION POND #2 CALCULATIONS Minimum Pond Surface Area: 292,300 Sq. Ft. (Impervious.), + 1 ,237,642 Sq. Ft. (total areal = 24% Impervious SA/DA % (See Chart) for 85% TSS Removal @ 4' Pond Depth = 1 .5% Area Total Drainage Area = 1 ,237,642 Sq. Ft. = 28.4 AC 1 .5% x 28.4 = 0.43 AC Required Pond Surface Area Pond #2 Area = 0.51 AC and is therefore adequate. Stormwater Storage Depth.: 39,9.54 CF (Runoff) ; 22,216 Sq. Ft. (Pond Areal = 1 .8' Storage Depth Required ORIFICE DISCHARGE RATE CALCULATIONS= POND #2 Use 2.5" diameter orifice for Pond .#2 outlet. Calculate average discharge rate and time to lower orifice head from 1 .90' to 1 .80' : 0.10' pond height x 22,215 Ft2 pond area x 7.5 gal/Ft3 = 16,661 Gal . Storage Average head on orifice from 1.90' to 1 .80' = 1 .85' Average discharge rate @ 1 .85' head: Q(GPM) = (449)c A Q(GPM) = (449) (.6)( .0341) 42(.32.2) (1 .85) Q = 100 GPM Time required to lower pond 0.1 ' @ 1 .85' average head: T = 16,661 Gal . = 100 GPM = 166 minutes 100 GPM vs 166 minutes plotted on discharge curve (See Discharge Curve) Discharge rate and time to lower head from 1 .80' to 1 .70' : Q = 98 GPM T = 16,661 Gal . : 98 GPM = 170. minutes 98 GPM vs 336 minutes plotted on curve. Discharge rate and time to lower head from 1 .70' to 1 .60' : Q = 95 GPM T = 16,661 Gal . j 95 GPM = 175 minutes 95 GPM vs 511 minutes plotted on curve. Discharge rate and time to lower head from 1 .60' to 1.50' : Q = 92 GPM T = 16,661 Gal . j 92 GPM = 181 minutes 92 GPM vs 692 minutes plotted on curve. Discharge rate and time to lower head from 1 .50' to 1 .40' : Q = 89 GPM. T = 16,661 Gal . = 89 GPM = 187.minutes 89 GPM vs 879 minutes plotted on curve. Discharge rate and time to lower head from 1 .40' to 1 .30' : Q = 86 GPM T = 16,661 Gal .. j 86 GPM = 194 minutes 86 GPM vs 1 ,073 minutes plotted on curve. Discharge rate and time to lower head from 1.30' to 1 .20'.: Q = 82 GPM T = 16,661 Gal . = 82 GPM = 203 minutes 82 GPM vs 1 ,276 minutes plotted on curve. Discharge rate and time to lower head from 1 ,20' to 1 .10' : Q = 79 GPM T = 16,661 Gal . = 79 GPM = 211 minutes 79 GPM vs 1 ,487 minutes plotted on curve. Discharge rate and time to lower head from 1 .10' to 1 .00' ; Q = 76 GPM T = 16,661 Gal . = 76 GPM = 219 minutes 76 GPM vs 1 ,706 minutes plotted-on curve. Discharge rate and time to lower head from 1.00' to 0.90' : Q = 72 GPM T = 16,661 Gal . + 72 GPM = 231 minutes 72 GPM vs 1 ,937 minutes plotted on curve. Discharge rate and time to lower head from 0.90' to 0.80' ; q = 68 GPM T = 16,661 Gal . = 68 GPM = 245 minutes 68 GPM vs 2,182 minutes plotted on curve. Discharge rate and time to lower head from 0.80' to 0.70' : Q = 64 GPM T = 16,661 Gal . s 64 GPM = 260. minutes 64 GPM vs 2,442 minutes plotted on curve. Discharge rate and time to lower head from 0.70' to 0.60' : Q = 59 GPM T = 16,661 Gal . = 59 GPM = 282 minutes 59 GPM vs 2,724 minutes plotted on curve. Discharge rate and time to lower head from 0.60' to 0.50' : Q = 55 GPM T = 16,661 Gal . j 55 GPM = 303 minutes 55 GPM vs 3,027 minutes plotted on curve. Discharge rate and time to lower head from 0..50.` to 0.40' : Q = 49 GPM T = 16,661 Gal . = 49 GPM = 340 minutes 49 GPM vs 3,367 minutes plotted on curve. Discharge rate and time to lower head from 0.40.' to 0.30' : Q = 44 GPM T = 16,661 Gal . i 44 GPM = 379 minutes 44 GPM vs 3,746 minutes plotted on curve. Discharge rate and time to lower head from 0.30' to 0.20' : Q = 37 GPM T = 16,661 Gal . = 37 GPM = .450 minutes 37 GPM vs 4,196 minutes plotted on curve.. Discharge rate and time to lower head from 0.20' to 0.10' : Q = 29 GPM T = 16,661 Gal . i 29 GPM = 575 minutes 29 GPM vs 4,771 minutes plotted on curve. Discharge rate and time to lower head from 0.10' to 0.00' : Q = 16 GPM T = 16,661 Gal . = 16 GPM = 1 ,041 minutes 16 GPM vs 5,812 minutes plotted on curve. The outlet structure will discharge the total calculated runoff volume of 299,655 gallons in approximately 3.7 days (See Orifice Discharge Curve) . DISCHARGE RITE (+P o o o • 0 o o 0 0 o . . . . . . I I I I I. - �� k ��� 0 - # _ \ _ \/\ ck. etf r 0.4, -6§n . . . . . . . . . . . . .. . . . PO & -0 77 $O o 0lis o A 22 O 0 O " _ _N� O 0 Z I Z VAS - & m R / t..4 " Z SI ,a,- t JO o ,ao » m 0 IN cs 70 C t\� m A mR .2 la ,o §§o + > ku 7 ® 3 o /<+I/-.41' m /o 44 . Z %, 13 ITT . m %a% % o o 2 �. o o +»p is 4 44¥ ��0 r _&13o _ o a 2 / --0 . // CC it.\ ■ w — t) N o a . / A ] m 2 # Atr% R - 0 / 1, 0 0 o 4 % 0 2, 2 .• o w r o -a - tit 2 11 • e 2 r- 5\ r I- icoefe, RUNOFF CALCULATIONS - AREA #3 2��1 Impervious Surfaces: 12 Lots (2,300 Sq. Ft. Each) = 30,000 Sq. Ft. Streets = 19,800 Sq. Ft. Off Site (1040 LF± 8' wide cart path) = 8,320 Sq. Ft. Total Impervious Area = 58,120 Sq. Ft. Pervious Surfaces: Project Lawns, Street Shoulders, etc. = 175,000 Sq. Ft. Off Site (Undeveloped Area, Fairway, etc. ) = 45,000 Sq. Ft. Total Pervious Area = 220,000 Sq. Ft. 58,120 Sq. Ft. (Impervious) x .083' = 4,824 CF Runoff 220,000 Sq. Ft. (Pervious) x .083' x 0.20' = 3,652 CF Runoff Total Runoff = 8,476 CF (_63,570 Gal . ) DETENTION POND #3 CALCULATIONS Minimum Pond Surface Area: 58,120 Sq. Ft. (Impervious) = 278,120 Sq. Ft. (Total Drainage Area) = 21% Impervious Area SA/DA % (See Chart) for 85% TSS Removal @ 4' Depth = 1 .3% Total Drainage Area = 278,120 Sq. Ft. = 6,38 AC 1 .3% x 6.38 AC = 0.08 AC Required Pond Area Pond #3 Area = 0.10 AC and is therefore adequate Stormwater Storage Depth.: 8,476 CF (Runoff) = 4,356 Sq. Ft. (Pond Areal_ = 1 .9' Storage Depth. Required ORIFICE DISCHARGE RATE CALCULATIONS - POND #3 Use 1/2" diameter orifice for Pond #3 outlet Calculate average discharge rate and time to lower orifice head from 1 .90' to 1 .70' : 0.20' pond height x 4,356 Ft2 pond area x 7.5 gal/Ft3 = 6,534 gal . storage Average head on weir from 1 .90' to 1 .70' = 1 .80' ` Conu?r-ls i i_'°"t Average dischargerlrate @ 1 .801 : Q(GPM) = (449)(.6)(.0055)1/2(32.2)(1 ,80) Q = 15.7 GPM Time required to lower pond 0.20' @ 1 .80' average head: T = 6,534 Gal . = 15.7 GPM = 416 minutes 15.7 GPM vs 416 minutes plotted on curve (See Discharge Curve). Discharge rate and time to lower head from 1.70' to 1 .50' : Q = 15.0 GPM T = 6,534 Gal . = 15.0 GPM = 436 minutes 15.0 GPM vs 852 minutes plotted on curve. Discharge rate and time to lower head from 1 .50' to 1 .30' : Q = 14.0 GPM T = 6,534 Gal . = 14.0 GPM = 467 minutes 14.0 GPM vs 1 ,318 minutes plotted on curve. Discharge rate and time to lower head from 1 .30' to 1 .10' : Q = 13.0 GPM T = 6,534 Gal . = 13.0 GPM = 503 minutes 13.0 GPM vs 1821 minutes plotted on curve. Discharge rate and time to lower head from 1 .10' to 0.90' : Q = 11 .9 GPM T = 6,534 Gal . = 11 .9 GPM = 549 minutes. 11 .9 GPM vs 2,370 minutes plotted on curve. Discharge rate and time to lower head from 0.90' to 0.70' ; Q = 10.6 GPM T = 6,534 Gal . = 10.6 GPM = 616 minutes 10.6 GPM vs 2,986 minutes plotted on curve. Discharge rate and time to lower head from 0.70' to 0.50' : Q = 9.2 GPM T = 6,534 Gal . = 9.2 GPM = 710 9.2 GPM vs 3,696 minutes plotted on curve. Discharge rate and time to lower head from 0.5Q' to 0.30' : Q = 7.5 GPM T = 6,534 Gal . = 7.5 GPM = 871 minutes 7.5 GPM vs 4,547 minutes plotted on curve. Discharge rate and time to lower head from 0.30' to 0.10' ; Q = 5.3 GPM T = 6,534 Gal . = 5.1 GPM = 1 ,281 minutes 5.3 GPM vs 5,799 minutes plotted on curve. Discharge rate and time to lower head from 0.10' to 0.00' : Q = 2.7 GPM T = 3,267 Gal . = 2.7 GPM = 1 ,210 minutes 2.6 GPM vs 7,009 minutes plotted on curve. The outlet structure will discharge to total calculated runoff volume of 63,570 gallons in approximately 4.7 days (See Orifice Discharge Curve). DISCHARGE RATE (GPM) a 01 d w n 1 1 p7 /14.,--,-;.— O-J/f ` NOS o o =34Tv ..6" sb oueo (-R N m Z:. // ".o mwiti3w Cum c _' NZ:- D 44 — v;4O ` a °�c' le, Q `Q - 0 z o r �.o� 3 0 4 ° O a.NN .1 .4 4p � r- at i :4 Z' ',$ 7d 4 rft �f t•ra �3 • T'A Z h-- V f IT "r a -I o V 01(JP• 111 U a im% (� s ()I -c .V N SJ, -4 .i Az NI I r -4.titzi 4a r- OAKBROOK= SA/DA - 85% TSS REMOVAL WITH 30' VEGETATIVE FILTER IMPER.% 3 . 0FT 3 .5FT cOFT)4. 5FT 5 . 0FT 5. 5FT 6.0FT 6 . 5FT 7. 0FT 7. 5FT po,va 1 10% 19� . 9 .8 hZ . 7 . 6 . 5 poN0,.3 20% 21% 1.7 1.3 1,3 1. 2 1. 1 1. 0 .9 .8 .7 .6 . 5 PDNa#a 3 0%2¢%2.5 2.2 1' 1.9 1. 8 1 . 6 1.5 1.3 1.2 1. 0 .9 40% 3 .4 3. 0 2.6 2. 4 2. 1 1.9 1. 6 1. 4 1.1 1. 0 50% 4.2 3 .7 3 .3 3. 0 2. 7 2 .4 2.1 1.8 1. 5 1.3 60% 5.0 4. 5 3 .8 3. 5 3 . 2 2. 9 2.6 2. 3 2. 0 1.6 70% 6. 0 5. 2 4.5 4.1 3 .7 3.1 2. 9 2.5 2. 1 1.8 80% 6 .8 6.0 5.2 4.7 4. 2 3 .7 3 .2 2.7 2. 2 2. 0 90% 7.5 6.5 5. 8 5 .3 4 . 8 4.3 3 .8 3 .3 2.8 1.3 100% 8.2 7. 4. 6. 8 6. 2 5. 6 5.0 4. 4 .3 .8 3.2 2. 6 SA/DA - > 90% TSS REMOVAL FOR WET DETENTION WITHOUT VEGETATIVE FILTER IMPER. % 3 . 0FT 3 . 5FT 4. 0FT 4. 5FT 5 . 0FT 5.5FT 6. OFT 6.5FT 7.0FT 7. 5FT 10% 1.3 1. 0 . 8 .7 . 6 .5 . 4 .3 .2 . 1 20% 2. 4 2. 0 1. 8 1.7 1. 5 1.4 1.2 1. 0 . 9 . 6 30% 3 .5 3 .0 2.7 2 .5 2. 2 1.9 1. 6 1. 3 1.1 . 8 40% 4.5 4.0 3 .5 3 .1 2. 8 2. 5 2 .1 1. 8 1. 4 1 . 1 50% 5. 6 5 . 0 4.3 3 .9 3 . 5 3 . 1 2. 7 2.3 1 . 9 1.5 60% 7.0 6 . 0 5 .3 4. 8 4. 3 3 . 9 3. 4 2. 9 2. 4 1. 9 70% 8.1 7. 0 6 . 0 5. 5 5 . 0 4.5 3 . 9 3 .4 2. 9 2 . 3 80% 9. 4 8. 0 7.0 6. 4 5 .7 5.2 4. 6 4. 0 3 . 4 2. 8 90% 10.7 9. 0 7.9 7. 2 6 .5 5.9 5.2 4. 6 3 . 9 3 .3 100% 12.0 10.0 8.8 8.1 7. 3 6.6 5.8 5.1 4.3 3 .6 'eni-�i\3 /( / /LJ /0 4,---4*)//. ,A1WM4') m I'-',f ';-11f7 ,17,1 ir"--7 1 1, it:, l \ id ys , '..�, January 11, 1989 Mr. Mark Hawes N.C. Division of Environmental Management 7225 Wrightsville Avenue Wilmington, North Carolina 28403 Subject: Statement of Responsibility Stormwater System Operation and Maintenance Oakbrook III at Brick Landing Plantation Brunswick County Dear Mr. Hawes: This letter acknowledges that a Stormwater Management Plan has been submitted on behalf of Oakbrook III at Brick Landing Plantation. Brick Landing Plantation Homeowner's Association will be responsible for the op- eration and maintenance of the system as required by DEM and the operation and maintenance procedures included as an integral part of the Stormwater Management Plan. Brick Landing Plantation Homeowner's Association will be responsible for repair- ing or replacing any part of the Stormwater Management system which may become inoperable. Sincerely, /.. .....„1...V H. Michael Brazeal Project Director cc: Joseph S. Hill, Jr. and Assoc. Ocean Isle Beach,North Carolina 28459 919-754-4373 Inside NC 1-800-222-9938 Outside NC 1-800-438-3006