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Home My WebLink AboutSW8060813_COMPLIANCE_20061117STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE 07 COMPLIANCE EVALUATION INSPECTION DOC DATE 7 YYYYMMDD WET DETENTION POND ANALYSIS FILE NAME: S:IWQSXSTORMWATERIPOND1660813.aug06.WK1 .. .. ........................... ........................ PROJECT#: SW8 1aug REVIEWER :::L.:.:. 'L::0m$ -Yn PROJECT NAME: Q.0 M. :Commons DATE: 17-Nov-06 "C'. 'e Receiving Stream: UTZMfthk Class: ...... XX: Drainage Basin: Index No. Site Area 7 a 5 6:-:-:. acres ..... ..... Drainage Area 224900 QO square feet Area in Acres 5.16 IMPERVIOUS AREAS Buildings Parking SW TOTAL SURFACE AREA CALCULATION % IMPERVIOUS Des. Depth TSS, 85 or 90: 44.46% .. .. .. .. .. square feet square feet square feet square feet square feet square feet square feet square feet Rational C 0.90 0.90 0.90 Rational Cc= 0.51 SA/DA Ratio 3.46% Req. SA 7775 sf Prov. SA sf VOLUME CALCULATION * place a "'I" in the box if Rational is used Rational ?* Des. Storm inches Rv= 0.450 Bottom msl Perm. Pool rnsl Design Pool msi Storage met @elev 28.09 msI Req. Volume 9582 cf Vol. Prov. at DP 10506cf ORIFICE CALCULATION I FOREBAY Perm, Pool Volume= Req. Forebay Volume= 4261.6 Provided Volume= Percent= 18.8% Elevation Area Inc. Vol. Acc. Vol. 27-.00: :0 0.00 0.00 044 8755.00 8755.00 28.20 9480.00 .1889.00 10644.00 Avg. Head = 0.57 ft Q2 Area = 2.19 sq. inches Flow Q2, cfs; 0.055 cfs Q5 Area = 0.88 sq. inches Flow Q5, cfs 0.022 cfs. Orifice Area 1.54 sq. inches No. of Orifices Q= 0,039 cfs Diameter, inches in x in 1:404: weir H x W Drawdown = 2.9 days Surface Area @DP = 9672 sq. ft. Falling Head Drawdown = 4.4 days C: 3.320740741 L- -0.114 COMMENTS Surface Area , Volume and Orifice are within Design Guidelines WET DETENTION POND ANALYSIS FILE NAME: S:kWQSkSTORMWATERIPOND1060813.aug06.WKI PROJECT* SW8-- .......... REVIEWER .L Lewis .. .. .. .. .. i ' t ' ". PROJECT NAME: � � t�i 7 'S' ... 02: 'Q o rn m o n s Receiving Stream: Drainage Basin: Site Area Drainage Area k DATE: - 16-Aug-06 Class: Index No. acres square feet Area in Acres 5.16 IMPERVIOUS AREAS Rational C Buildings om . ..... '01 square feet XX Parking feet square feet SW Square feet .. . .......... . ...................... .. ..... square feet square feet square feet ........... TOTAL 100000.00 square feet Rational Cc= 0.11 SURFACE AREA CALCULATION % IMPERVIOUS 44.46% Des. Depth TSS, 85 or 90: VOLUME CALCULATION Bottom msl Perm. Pool msl Design Pool MSI Storage met @elev 28.03 msl Req. Volume 8437 cf Vol. Prov. at DP 1718 cf ORIFICE CALCULATION SA/DA Ratio 146% Req, SA 7775 sf Prov. SA sf * place a 1" in the box if Rational is used ;1910 4 I-T-1vil Perm. Pool Volume= Req. Forebay Volume= 4522 Provided Volume= Percent= 20.1% on Area Inc. Vol. Acc. Vol. .. . .. .. ....... $460 Mi 00 8130.00 8130.00 -X -X 9055.00 17185.00 Avg. Head = 0.98 ft Q2 Area = 1.48 sq. inches Flow Q2, cfs; 0.049 cfs Q5 Area = 0.59 sq. inches Flow Q5, cfs; 0.020 cfs Orifice Area 0.79 sq. inches No. of Orifices Q= 0,026 cfs Diameter, inches )Q�weir H x W in x in Drawdown = 3.8 Idays Surface Area gour = 9650 sq. ft. Falling Head Drawdown = 10.9 days C3.357037037 L= -0.196 COMMENTS Surface Area , Volume and Orifice are within Design Guidelines :OW STORMWATER SYSTEM NARRATIVE CORNERSTONE COMMONS WILMINGTON, NC For Cape Fear Habitat for Humanity, Inc. . 1208 Third Street Wilmington, North Carolina 28401 (910 6 -474.4 �OaQIH .CARb�� m� b m 9 SE AL a 10912 [°pO°ee C S dp6ppp August 11, 2006 Prepared by: 3 _ :ESP Associates,. P.A. y engineering • surveying •lilanning 2120-B Capital Drive, Wilmington, North Carolina 28405 910.313.6648 fax: 910.313.6823 www.ejpassociates.com ESP Project Number: TB35.400 NARRATIVE DESCRIPTION: The site is a 5.16-acre tract that is located in the City of Wilmington of New Hanover County. The tract is bounded by Mosley Road to the west, single-family development to the east, multi -family development to the south and well vegetated forest to the north. The site contains heavy vegetated areas. The site is gently rolling light to heavily vegetated sandy soils with poorly defined drainage patterns. All stormwater runoff from the site drains to Smith Creek. There are no regulated wetlands located in the proposed project area. The project is a new residential subdivision consisting of clearing, grading, and construction of roads, amenity area, stormwater management system and utilities. Design impervious for the entire site is computed at a maximum of 33%. About 5.16 acres will be disturbed by the construction work. The water supply will be dedicated to and operated by the City of Wilmington. The sewer collections system will be dedicated to and operated by the City of Wilmington. Both utilities will require state permits. An erosion control permit will be required from the state of North Carolina. Stormwater management permits will be required from the city and state. STORMWATER MANAGEMENT MEASURES: The site is proposed as high density, with a proposed maximum impervious surface of 33%. The site will be developed under the high -density guidelines using a wet detention pond for treatment. There is no direct discharge from impervious surfaces to a watercourse. The grading contractor and developer will provide maintenance during construction. The developer will provide maintenance after completion.