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HomeMy WebLinkAboutSW8060557_COMPLIANCE_20070119STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE COMPLIANCE EVALUATION INSPECTION DOC DATE YYYYMMDD STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE HOC DATE YYYYMMDD A� NCDENR North Carolina Department of Environment and Natural Resources Division of Coastal Management Michael F. Easley, Governor Charles S. Jones, Director William G. Ross Jr., Secretary January 19, 2007 MEMORANDUM: TO: Linda Lewis Stormwater Division of Water Quality FROM: Doug Huggett, Major Permits Coordinator SUBJECT: CAMA Permit Application Review b 05 Idti��2007 -. �I Applicant: CJL Partners c/o Frank Majewski for Sawgrass Point S/D Project Location: 800 block of N. New River Dr (NC Hwy 210), adjacent to Topsail -Sound, in Surf City, Pender County Proposed Project: to install a pier and platform, retaining wall, subdivide a parcel a�ndin�st2fll, associated road and utilities; Please indicate below your agency's position or viewpoint on the proposed project and return this form by February 12, 2007. If you have any questions regarding the proposed project, please contact Jon Giles at (910) 790-7221, when appropriate, in-depth comments with supporting data is requested. REPLY: This agency has no objection to the project as proposed. /6) _3._ ZC?C�&. This agency has no comment on the proposed project. This agency approves of the project only if the recommended changes are incorporated. See attached. This agency objects to the project for reasons described in the attached comments. SIGNED iV �� DATE Z—f s-Cam 127 Cardinal Drive Ext., Wilmington, North Carolina 28405-3845 Phone: 910-796-72151 FAX: 910-395-39641 Internet: www.nccoastalmanagement.net An Equal opportunity 1 Affirmative Action Employer - 50% Recycled 110% Post Consumer Paper N DIVISION OF COASTAL MANAGEMENT FIELD INVESTIGATION REPORT 1. APPLICANT'S NAME: C.J.L. Partners % Prank Majewski -/ Sawgrass Point 2. LOCATION OF PROJECT SITE: The project site is located in the 800 Block of North New River Drive.(NC Hwy 210), adjacent to Topsail Sound, in Surf City, Pender County. Photo Index — 2006: 25-6581: K,L(14,15) 2000: 25-331: L,M,N(10,1 1) 1995: 25-315: M,N(21,22) State Plane Coordinates — X: 2442234 Y: 252870 CPS File: P 122916A Lat:34026'08.91891'N Long: 77°32'00,05651"W 3. INVESTIGATION TYPE: CAMA 4. INVESTIGATIVE PROCEDURE: Dates of Site Visit — 12-29-06 Was Applicant Present — No 5. PROCESSING PROCEDURE: Application Received — Complete on 01/04/07 Office — Wilmington 6. SITE DESCRIPTION: (A) Local Land Use Plan -Town of Surf City Classification From LUP — Developed (A) AEC(s) Involved: OH & ES CC Water Dependent: Yes (D) Intended Use: Private / Commercial (E) Wastewater Treatment: Existing — N/A Planned - Municipal Sewer (F) Type of Structures: Existing —N/A Planned —Town homes, pier and dock, retaining wall, roadway and utilities. (G) Estimated Annual Rate of Erosion: 2' / year Source — LTAASCR 1998 Update 7. HABITAT DESCRIPTION: 1AREA1 DREDGED I II.Lf:U c l l l I: (A) Vegetated Wetlands Shaded 1410 ft.' (B) Non -Vegetated Wetlands - open water 200 ft.2 (incorporated) (C) Other (Highground) 47,915 ft2 (disturbed) (D) Total Area Disturbed: 49.525 ft' (E) Primary Nursery Area: Yes . (F) Water Classification: SA Open: Yes 8. PROJECT SUNEVIARY: The applicant is proposing to install a pier and platform, retaining pval1. subdivide a parcel and install associated road and utilities. 127 Cardinal Drive Ext., Wilmington, North Carolina 28405-3845 Phone: 910-796-72151 FAX: 910-395-39641 Internet: www.nccoastalmanagement.net An Equal Opportunity l Affirmative Action Employer — 50% Recycled 110% Post Consumer Paper C.J.L. Partners % Frank Majewski / Sawgrass Point Page Two I ip 9. PROJECT DESCRIPTION: The project site is located in the 800 Block of North New River Drive (NC Hwy 210), adjacent to Stump Sound. in Surf City, Pender County. To get to the site from Wilmington take US Hwy 17 N to NC Hwy 210. Turn right onto NC Hwy 210 and continue to NC Hwy 50. Take a right onto NC Hkw 50. Travel across the swing bridge to, NC Hwy 210. Take a right onto NC Hwy 210. Travel approximately one mile. The property is located on the right just past Egret Landing Subdivision and the adjacent cleared lot. The property is adjacent to NC Hwy 210 on the east side and is adjacent to Stump Sound on the west. The property is adjacent to residential properties on the north and south sides. The property is currently vacant and appears to be in a natural undisturbed state. The current elevation of the property ranges from 3' to 5' above mean sea level (MSL) and the property encompasses approximately 7.89 acres including approximately 1.1 acres of highground. The remainder of the property is §404 Wetlands and coastal wetlands. The highground portion of the property is vegetated primarily with Wax Myrtle (k1yrica cerifera), Live Oak (Quercus virginiana). Yaupon 1 ecd (c�larti (Juniperus virginiana) and a dense understory. The project site has approximately 1.1 acres of hi�u112YOund (h, remaining 6.79 acres is a combination of §404 Wetlands and coastal wetlands. The high marsh portion of the coastal wetlands ranges from 230' to 180' in width and consist mainly of Cattail (Typha, spp.), Black Needlerush (Juncus roemarianus), Sea Lavender (Limonium, spp.), Salt Meadow- Grass (Spartina patens). Salt Marsh Cordgrass (Spartina alterniflora) and Glasswort (Sahcornia spp). The high marsh area transitions to lo%v marsh that consists of mainly Salt Marsh Cordgrass and varies in width -from 10' to 60'. The normal hi�(lh %�Llk2¢- (NHW) line is located along the transition from high marsh to low marsh. c The Town of Surf City Land Use Plan classifies the upland areas of this project as Developed. The x%atcrs ol' 0ic project site are classified as SA by the NC Division of Water QualitV. -1 \C DIVIS1011 designated this area of Stump Sound,as a Primary Nursery Area; and the waters adjacent to the project are open to the harvesting of shellfish. PROPOSED PROJECT: The applicant is proposing to construct 17 Town homes on the 1.1 acres of highground at a density of 16 units/acre. The applicant is also proposing to install a pool, and 12,622 ft.' of driveway and parking? area. The access to the proposed development would be located on the northern side of the property. The applicant is proposing to install 791 linear feet of retaining wall beginning at the NC Hwy 210 right-of-way on the southern property line and continued in a westerly direction approximately 180'. Then the retaining wall would run 110111, the §404 Wetland line in a northerly direction, the alignment of the proposed wall would match the tbotprints of the town homes and proposed. pool area to the northern property line and then would turn east to the intersection of NC Hwy 210 right-of-way. The applicant is planning to connect to the Town of Surf City water and sewer services. There are two proposed swales and an infiltration bed located at the road between the town home units and 10" roof drains, which would receive runoff from the 9 units located on -the estuarine side of the development. These devices would route the runoff to a stormwater storage system measuring 150' in length and 15' in width located on the northern property line. The applicant is also proposing a 6' x 235' pier with a 10' x 20' T-head. The channel is approximately 40 in width at the location of the proposed pier. The water depth at the end of the pier would be approximately -0.75' @ Normal Low Water (NLW). There are no slips proposed with the pier and dock. 127 Cardinal Drive Ext., Wilmington, North Carolina 28405-3845 Phone: 910-796-72151 FAX: 910-395-39641 Internet: www.nccoastaimanagement.net An Equal Opportunity 1 Affirmative Action Employer - 50% Recycled ti 10% Post Consumer Paper I C.J.L. Partners % Frank Majewski / Sawgrass Point Page Three 10. ANTICIPATED IMPACTS The proposed project would disturb approximately 47,915 ft.2 of highground located entirely in the High Hazard Flood Area of Environmental Concern (AEC). The road installation would create approxitnatek, 47.91 ft.' of impervious area located in the High Hazard Flood Area (AEC). The proposed pier would sli idc .tppru�in .tt•_ i� 1410 ft.z of coastal wetlands and the T-head would incorporate approximately 200 ft.' of estt.tarine v, atcrs 111d public trust area. Submitted by: J. W. Giles Date: January 10, 2007 Office: Wilmington 127 Cardinal Drive Ext., Wilmington, North Carolina 28405-3845 Phone: 910-796-72151 FAX: 910-395-39641 Internet: www.nccoastalmanagement.net An Equai Opportunity.l Affirmative Action Empioyer — 50% Recycled 1 10% Post Consumer Paoer RECEIVED Stormwater Treatment & DCM WILMINGTON, NC DEC � s zoos Erosion Control Narrative Sawgrass Point CJL Partners, Inc. proposes to build a residential townhome development on a 7.89 acre tract located on NC 210 (New River Drive) close to its intersection with NC 501210 in Surf City, N.C. (Topsail Township), Onslow County. The site is currently vacant. The proposed development includes seventeen (17) townhome units, pool, and associated sitework. The intended use of the project, when complete, is RESIDENTIAL. The project is to be designed and constructed in accordance with NC Division of Environmental Management Stormwater Management Rules (15A NCAC 2H.1000). Section .1005(2)(b). The proposed project is "High Density" (i.e., percent impervious > 25%). Division of Water Quality requires that the first 1.5" of rainfall be treated in an infiltration system. The project site is located less than 1 mile from the Intracoastal Waterway (SA:HQW) in the Cape Fear Basin. Existing site topography is gently sloping (0 -- 6%), draining towards the rear (northwestern) portion of the site. Topography suggests that precipitation currently infiltrates into the sandy soils or sheet flows into adjacent wetlands. Soils are Medium to Coarse Sands (see attached soils evaluation) which have hydraulic conductivities ranging from 10 — 20 in/hr. In order to provide adequate cover over proposed stormwater infiltration facilities, it is necessary to fill the upland portion of the project area to approximately Elevation 8.5. A retaining wall is proposed upgradient of the 404 and coastal wetland delineations. Retaining wall is to be of conventional design/construction (treated wood piles, vinyl panels). No fills are proposed in wetland areas. Upon placement of fill, proposed grading activities will be limited to installation of building pads and sloping parking areas as minimally required for drainage. The site will be drained to one proposed infiltration system. The developer plans to construct a wooden walk and dock (total .length 235') to provide access to adjacent, existing canal. Dock will be of conventional design/construction (treated wood piles, treated wood decking & railing). Form DCM-MP- I RECEIVED DCh1 WILiMINGTON, NC APPLICATION (To be completed by all applicants) 1. APPLICANT a. Landowner: Name C.r.L Partners, Inc. tr-, Address 2828 Brenfield Dr. - City Raleigh State NC Zip 27606 Day Phone (919) 427-2397 Fax (919) 854-2932 b. Authorized Agent: Name David K. Newsom (Crystal Coast Engineering, PA) Address 3817-3 Freedom Wav City Hubert State NC Zip 28539 Day Phone (910) 325-0006 Fax (910) 325-0060 c. Project name (if any) Sawgrass Point NOTE: Permit will be issued in name of landowner(s), and/or projecl name. 2. LOCATION OF PROPOSED PROJECT a. County Pender b. City, town, community or landmark Surf City, NC c. Street address or secondary road number NC Hwy 210 (N. New River Drive) d. Is proposed work within city limits or planning jurisdiction? X Yes No e. Name of body of water nearest project (e.g. river, creek, sound, bay) Topsail Sound 1 Adandc Intracoastal Waterway 3. DESCRIPTION AND PLANNED USE OF PROPOSED PROJECT a. List all development activities you propose (e.g. building a home, motel, marina, bulkhead, pier, and excavation and/or filling activities. Propose grading of lot, construction of associated roadways, parking, stormwater system, utility poles, sewer system and public water system_ 0 I ?, 4c i b. Is the proposed activity maintenance of an existing project, new work, or both? newwork c. Will the project be for public, private or commercial use? private (new residential homes) d. Give a brief description of purpose, use, methods of construction and daily operations of proposed project. If more space is needed, please attach additional pages. Heavy machinery will be used to clear & grade the building lots, as well as the associated infrastructure that includes. constructing drives/parking, stormwater treatment system, sewer and water systems and utility poles_ Revised 03/95 RECEIVED DCM WILMINGTON, NC Form DCM-MP-1 4. LAND AND WATER CHARACTERISTICS a. Size of entire tract 7.89 acres b. Size of individual lot(s) see plans c. Approximate elevation of tract above MHW or N W L Existing-4.0 1 Proposed-9.0 d. Soil type(s) and textures) of tract medium to coarse sand & coarse sand with shell; very friable to loose e. Vegetation on tract Grass scrub, pine, small oaks f. Man-made features now on tract none g. What is the CAMA Land Use Plan land classification of the site? (consult the local land use plan,) Conservation Transitional X Developed Community Rural Other h. How is the tract zoned by local government? AIfu Is the proposed project consistent with the applicable zoning? X Yes No (Attach zoning compliance certificate, if applicable) Has a professional archaeological assessment been done for the tract? Yes X No if yes, by whom? NIA k. Is the project located in a National Registered Historic District or does it involve a National Register listed or eligible property? Yes X No Are there wetlands on the site? X Yes No Coastal (marsh) X Other If yes, has a delineation been conducted? YES (Attach dncumentation. if available) D E C 0 8 2006 m. Describe existing wastewater treatment facilities. None existing. Proposed sewer system will be public ('town of Surf City), w/ maintenance agreement with developer (i.e. developerihomeowners pay for maintenance.) n. Describe location and type of discharges to waters of the state. (For exam le, surface runoff, sanitary wastewater, Industrial/commercial effluent, "wash down" and residential discharges.) Stormwateronly; collected & treated with infiltration system; discharged to wetlands via vegetated filter in accordance with DWQ requirements. o. Describe existing drinking water supply source. None existing. Proposed water distribution system will be supplied by Town of Surf City. 5. ADDITIONAL INFORMATION In addition to the completed application form, the following items must be submitted: • A copy of the deed (with state application only) or other instrument under which the applicant claims title to the affected properties. If the applicant is not claiming to be the owner of said property, then forward a copy of the deed or other instrument under which the owner claims title, plus written permission from the owner to carry out the project. • An accurate, dated work plat (including plan view and cross -sectional drawings) drawn to scale in black ink on an 8 1/2" by l I" white paper. (Refer to Coastal Resources Commission Rule 7J.0203 for a detailed description.) Please note that original drawings are preferred and only high quality copies will be accepted. Blue -line prints or other,larger plats are acceptable only if an adequate number of quality Copies are provided by applicant. (Contact the U.S. Array Corps of Engineers regarding that agency's use of larger drawings.) A site or location map is a part of Plat requirements and it must be sufficiently detailed to guide agency personnel unfamiliar with the area to the Revised 03/95 RECEIVED DCM WILMINGTON, NC Form DCM-MP-I site. Include highway or secondary road (SR) numbers, landmarks, and the like. • A Stormwater Certification, if one is necessary • A list of the names and complete addresses of the adjacent waterfront (riparian) landowners and signed return receipts as proof that such Owners have received a copy of the application and plats by certified mail. Such landowners must be advised that they have 30 days in which to submit comments on the proposed project to the Division of Coastal Management. Upon signing,this form, the applicant further certifies that such notice has been provided. Name Address Phone Name Mctr,s Gnc� L ,,�c,n5 Address DEC 0 S 2006 6. CERTIFICATION AND PERMISSION TO ENTER ON LAND I understand that any permit issued in response to this application will allow only the development described in the application. The project will be subject to conditions and restrictions contained in the permit. I certify that to the best of my knowledge, the proposed activity complies with the State of North Carolina's approved Coastal Management Program and will be conducted in a maaner'consistent with such program. I certify that I am authorized to grant, and do in fact, grant permission to representatives of state and federal review agencies to enter on the aforementioned lands in connection with evaluating in related to this permit application and follow-up monitoring of the project. Phone I further certify that the information provided in this Name 1oft11r,QrzfS "�'l�lty application is truthful to the best of my knowledge. Address �,r�r Gu;�ncl l�ri� mac sat��.I1F}'�L45H0 Phone -f i Liv —�-,(`C' • A list of previous state or federal permits issued for work on the project tract. Include permit numbers, permittee, and issuing dates. NCDENR Erosion6edimentation Control permit issued 7/13106 to CJL Partners, Inc. (Project ID Pende-2006-425). Others pending (see attached) A check for $250 made payable to the Department of Environment, Health, and Natural Resources (DEHNR) to cover the costs of processing the application. • A signed AEC hazard notice for projects in oceanfront and inlet areas. A statement of compliance with the N.C. Environmental Policy.Act (N.C.G.S. 113A - I to 10) If the project involves the expenditure of public funds or use of public lands, attach a -statement documenting compliance with the North, Carolina Environmental Policy Act. This is the15� day of (� PT. Please indicate attachments pertaining to your proposed project. DCM MP-2 Excavation and Fill Information DCM MP-3 Upland Development DCM MP-4 Structures Information. DCM MP-5 Bridges and Culverts DCM MP-6 Marina Development NOTE. Please sign and date each attachment in the space provided at the bottom of each form. Revised 03195 Form DCM-MP-3 UPLAND DEVELOPMENT (Construction and/or land disturbing activities) Attach this form to Joint Application for CAMA. Major Permit, Form DCM-MP-1. Be sure to complete all other sections of the Joint Application that relate to this proposed project. a. Type and number of buildings, facilities, units or structures proposed 17Residential Townhcmeunits and associated parking, dock, stormwacer treatmont system, water & sewer systems.' b_ Number of lots or parcels 17 units. c. Density (give the number of residential units'aad the units per acre) 17 units; approx. 2 units/acre. (approx. l6 units/acre if 404 Wetlands area excluded) d- Size of area to be graded, filled or disturbed including roads, ditches, etc. 1.1 acre If the proposed project will disturb more than one acre of land, the Division of Land Resources must receive an erosion and sedimentation control plan at least 30 days before land disturbing activity begins. If applicable, has a sedimentation and erosion control plan been submitted to the Division of Land Resources? x Yes No -If yes, date submitted permit issued on 7/13/06 f. List the materials (such as marl, paver stone, asphalt, or concrete) to be used for paved surfaces. 1.5" SF 4.5 Asphalt; 6" ABC stone base 1 lV — i ad, S-. g. Give the percentage of the tract within 75 feet of MEW or NWL, or within 575 feet in the case of an Outstanding Resource Water, to be covered by impervious and/or built -upon surfaces, such as pavement, buildings, rooftops, or to be used for vehicular driveways or parking. 0%(only wood walk/deck) RECEIVED DCM ljkllLMINGTOK MC JAN 4 4 2007 h. Projects that require a CAMA Major Development Permit may also require a Stormwater Certification. Has a site development plan been submitted to the Division of Environmental Management for review? x Yes No If yes, date submitted approx, July 25, 2006 Describe proposed method of sewage disposal. Connect to public Sewer system (Town of Surf City); 8" D.I. gravity sewer Lines. Have the facilities described in Item i. above received state or local approval? pending DWQ Sw=—w (Attach appropriate documentation) ri �r �{ 1 SS't1 Cc� I C4.31 U4a Describe location and type of proposed discharges to waters of the state (for example, surface runoff; sanitary wastewater, industrial /commercial effluent, "wash down" and residential discharges). Storrnwater collected & treated in infiltration system & discharged to wetlands via vegetated filter in accordance with DWQ requirements. I. Describe proposed drinking. water supply source (e.g. well, community, public system, etc.) Connect to public water distribution systems (Surf City) m. Will water be impounded? Yes X No If yes, how many acres? n. If the project is a oceanfront development, when was the lot(s) platted and recorded? NIA C.J.L. Partners, Inc. (Sawgrass Point) Applicant :ii: !I E Revised 03/95 "I Form DCM-MP-4 STRUCTURES (Construction within Public Trust Areas) Attach this form to Joint Application for CAMA Major Permit, Form DCM-MP-1. Be sure to complete all other sections of the Joint Application which relate to this proposed project. a. Dock(s) and/or Pier(s) (1) _ Commercial Community X Private (2) Number I (3) Length 235 ft (4) Width 6 ft (5) Finger Piers Yes X No (1) Number (ii) Length (ill) Width (6) Platform(s) X Yes No (i) Number I (ii) Length 20 tc (iii) Width 4-f- i D (7) Number of slips proposed 0 (8) Proximity of structure to adjacent riparian property lines 59 ft (9) Width of water body 3 (IO)Water depth at water -ward end of pier at ML W or N \VL, -*77- 1. 7 5" ` r/- b. Boathouse (including covered lifts) Ik (1) Commercial Private (2) Length (3) Width c. Groin (e.g. wood; sheetpile, etc.) fV! i4- (1) Number (2) Length(s) d. Breakwater (e.g. wood, sheetpile, etc.) (1) Length (2) Average distance from MHW, NWL or wetlands (3) Maximum distance beyond MHW, NWL or wetlands RECEIVED DCM WILMING i ON. NC {,3Fc 0 S 200E Mooring buoys 04 (1) Commercial Community _ Private (2) Number (3) Description of buoy (Color, inscription, size, anchor, etc.) (4) Width of water body (5) Distance buoy(s) to be placed beyond shoreline Mooring structure (boatlift, mooring pilings, etc.) /)IA- (1) —Commercial _Community —Private (2) Number (3) Length (4) Width g. Other (ci e complete description) 79 �.S�� t iCf�sc j2��Gi r1rf?�i ti %�i l ll C.J.L. Partners, Inc. (Sawgrass Poi Signature Date Revised 03195 Front Elo-vation L' NOTE-6 i� d�� "drQc �F L7c�r'LIrY - �Ti;-�rZ —u7l /- T- = Zo, <- LtD r Crystal Coast Engineering, P.A. Civil and Environmental Consulting Engineers David K. Newsom, PE 3817-3 FREEDOM WAY, HUBERT, N.C. '28539 PHONE: (910) 325-0006 FAX: (910) 325-0060 I FRONT BUILDING ELEVATION SUPPLEMENT PREPARED FOR SAWGRASS POINT Topsail Township - Pender County SCALE; NO SCALE REV: DATE: JANUARY 10, 2007 PROJECT: 05-027 DRAWN BY: BA/DKN SHEEP SUPPLEMENT INFILTRATION TRENCH ANALYSIS Filename: S:1WQS11NTRENCH1060557.ju106 Project # SWE Project Name Recvng Stream Drainage Basin Site Area 0 5 Sawgrass Point ' . C:F .2 Impervious Area Calculation Volume/Storage Calculation acres If Rational Method is used, place a 1 in this box 0 Cc= 0.85 Required Design Storms in RV 0.79 Volume to Store 35fiS CF Provided Pipe Diameter Length Of a Single run of Pipe Number of Pipe Runs in Trench Storage In Piping Total Storage in Piping Cross -Sectional Area Of Pipe Runs Length Of Trench Width Of Trench Height Of Trench Cross -Sectional Area Of Trench Voids Volume, 40% Total Voids Volume Total Volume Provided Bottom Elevation SHWT Elevation Overflow Elevation V �WIOHQ n1 CQ QluCwlllUcl Vlll%O Pibe Size 1 Pipe Size 2 2.5 Feet Feet;:..: :::.:_:.::< ......5: :.: each Cubic Feet Cubic Feet 24.544 0.000 SF 34.50 :......... 7 13: ... ...... :...... Ia Exfiltration Rate / Drawdown Reported Hydraulic Conductivity Bottom Surface Area of Sidewinder Units Drawdown Time 25 YEAR 24 HOUR STORM N/A Intensity, i = .33 inches / hour Qr=CiA= Op through the bottom of the basin= 10 YEAR 10 MIN HIGH INTENSITY EVENT Intensity, i = 6.3 inches / hour Volume for 10 yr. 10 min. event = 0.23 CFS 0.0263 CFS 2691.19 CF < Feet Feet Feet SF CF CF Cubic Feet Mean Sea Level Mean Sea Level Mean Sea Level Q 667: Cubic Feet Per Hour Per Sq Ft 142.0 Square Feet 37.65 hours Must be > Qr 3755 CF Design Calculations Infiltration System for Sawgrass Point December 12, 2005 (Revised 5/31/06) I. Project Description The project consists of construction of residential condominiums and associated sitework on a 7.89 acre tract located on N.C. Hwy. 210 in Surf City near its intersection with Shell Drive. 2. Design Requirements Project will be designed in accordance with NC Administrative Code Section 15A NCAC 2H.1000 — Stormwater Management (hereinafter "Regulations". Due to density, the project is considered "high density development". Runoff in excess of the design volume must flow overland through a vegetative filter. 3. Impervious Surface Areas On -site Buildings On -site Streets On -site Parking On -site Sidewalk Reserve for Future Total Drainage Area Percent Impervious 4. Design Volume = 29,683 sf / 36,332 sf = 81.70 % 16,068 sf 12,622 sf 993 sf 5 E P Q 5 2006 0 sf SfN�GYpO���- 29,683 sf 36,332 sf In accordance with Section. 1008(c)(1), the required design volume is computed as follows: Using Schuler "Simple Method": Rv — 0.05 + 0.009(l) where I = Percent Impervious (81.70%) = 0,78530 in/in Design Volume = Design Rainfall (1.5") x Rv x Drainage Area = 1.5" x 0.78530 x 36,332 sf = 42,798 in-sf or 3,567 cf 5. Storage Volume The "Storage Area" is sized accommodate the Design Volume in a series of 30" HDPE pipes: 30" HDPE Manifold 15 If @ 4.906 cf/If 73 cf 30" HDPE Pipe 750 If @ 4.906 cf/lf 3,680 cf Total Storage Volume 3,753 cf 6. Infiltration Area Infiltration area is sized to accommodate actual storage volume (3,753 cf) pumped down in 2.0 days. Required infiltration rate (and associated stormwater pumping rate) is computed as follows: Infiltration (Pump) Rate = 3,753 cf / (2.0 day x 24 hr/day) = 78.19 ct hr (9.75 gpm) Stormwater Pump Station shall be designed and adjusted to deliver approximately 10 gpm to the infiltration system which is sited upland from the Storage Area in order to comply with required separations from SHWT. The Soil and Sue Evaluation Report (copy attached) indicates that existing soils are clean, well graded, coarse to medium sands with hydraulic conductivities ranging from 10-20 in/hr. Assuming conservatively that existing soils have a minimum hydraulic conductivity of 8.0 in/hr, required infiltration area is computed as follows: Req'd Infiltration Area = 78.19 cflhr 1 (8.0 indtr / 12 in/ft) = 117.28 sf Use eight (8) standard "Infiltrator" units which will provide 142 sf of surface area. Design Calculations Stormwater Pump Station for Sawgrass Point located in Surf City, North Carolina 1. Project Description CA .C,Q�4F�' •b��C 9 ,i 5 AL it 148 P. rOi�, n, �tNG��.•0���� i K. NLV r The stormwater treatment system serving Sawgrass Point will require a small pumping system to deliver stormwater from the storage area to the infiltration bed. 2. Pipe Effective Lengths 2" Pump Station Piping Actual Length = 8 No. Fitting Type LID L Total 1 gate valve 35 5.8 5.8 1 check valve 135 22.5 22.5 2 90 bend 20 3.3 6_6 FittingNalve Length — 34.9 2" Forcemain Pipe Total Effective Length = 42.9' Actual Length = 348' No. Fitting Type LID L Total 2 90 degree bend 20 3.3 6.6 0 45 degree bend 10 1.7 0.0 0 22.5 degree bend 5 0.8 0_0 FittingNalve Length 6.6 Total Effective Length = 354.6' 3. Pump Selection & Operating Conditions Pump Selection — Myers S33 Operating Conditions: 26 GPM @ I TDH — See attached spreadsheet Throttle pump in field to deliver 10.0 gpm. Forcemain/Pump System Model Enter data in shaded areas. Project: By: Date: Pump Off Elevation Forcemaln High Point: Forcemain Discharge Elevation: Pipe Section Pipe Material C Diameter 1(inches) Actual Equiv. Effective I Length Length Length Section 1 Section 2 SSection 3 ection 4 ........ .::. sy�y v> =' r, ....... � yy. 42.9 354.E F'lo Flow Rate Interval: Head loss calculated using Hazen -Williams e H, _ .2083(100/C) "'(Q 1.B5ro48555) where: Hf - friction loss in ft/100 0 - Row in gpm D - diameter in inches Pump Rate (gpm) Section 1 Hf Velocity Section 2 Hf Velocity Section 3 Hf Velocity Section 4 Hf Velocity Total Friction Loss 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 0.01 0.20 0.07 0.20 0.00 0.82 0.00 0.82 0.07 4 0.03 0.41 0.24 0.41 0.00 1.63 0.00 1.63 0.26 6 0,06 0.61 0.50 0.61 0.00 2.45 0.00 2.45 0.56 8 0.10 0.82 0.85 0.82 0.00 3.27 0.00 3.27 0.95 10 0.15 1.02 1,28 1.02 0.00 4,09 0.00 4.09 1.44 12 0.22 1.23 1.79 1.23 0.00 4.90 0.00 4.90 2.01 14 0.29 1.43 2.39 1.43 0.00 5.72 0,00 5.72 2.67 16 0.37 1.53 3.05 1.63 0.00 6.54 0.00 6.54 3.42 18 0.46 1.84 3.80 1.84 0.00 7.36 0.00 7.36 4.26 20 0.56 2,04 4.62 2.04 0,00 8.17 0,00 8.17 5.17 22 0.67 2.25 5.51 2.25 0.00 8.99 0.00 8.99 6.17 24 0.78 2A5 6.47 2.45 0.00 9.81 0.00 9.81 7.25 26 0.91 2.66 7.50 2.66 0.00 10.63 0.00 10.03 8.41 28 1.04 2.86 8.60 2.86 0.00 11.44 0.00 11.44 9.64 30 1.18 3.07 9.77 3.07 0,00 12.26 0.00 12.26 10.95 32 1.33 3.27 11.01 3.27 0.00 13.08 0.00 13.08 12.34 34 1.49 3.47 12.32 3.47 0.00 13.90 0.00 13.90 13.81 36 1.66 3.68 13.69 3.68 O.DO 14.71 0.00 14.71 15.35 equation: Static Bead TDH (ft) 3.50 3.50 3.50 3.57 3.50 3.76 3.50 4.06 3.50 4.45 3.50 4.94 3.50 5.51 3.50 6.17 3.50 6.92 3.50 7.76 3.50 8.67 3.50 9.67 3.50 10.75 3.50 11.91 3.50 13.14 3.50 14.45 3.50 15.84 3.50 17.31 3.50 18.85 SYSTEM CURVE VS. PUMP CURVE 35.00 30.00 25.00 0 20.00 15.00 10.00 5.00;� 0.00 0 4 8 12 16 20 24 28 32 36 40 44 48 PUMP RATE (GPM) TDH (f#) PUMP