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Home My WebLink AboutSW3171201_Design Calculations_20180827STORMWATER BMP CALCULATIONS VILLAGE AT GRANITE QUARRY - PHASE 1 Granite Quarry, Rowan County, North Carolina Prepared for: LGI HOMES Contact: Jeff Webb 3037 Sherman Drive Lancaster, SC P. 844-566-4300 Prepared by: DPR Associates, Inc. 420 Hawthorne Lane Charlotte, NC 28204 P. 704-332-1204 F. 704-332-1210 www.dprassociates.net DPR Project No.: 17031 November 27, 2017 February 26, 2018 March 30, 2018 June 25, 2018 6-25-2018 _______________________ _____________________ DPR Associates, Inc. Hy V. Nguyen, PE DPR Associates, Inc. Michael Barefoot, PE TABLE OF CONTENTS I. NARRATIVE II. BMP SUMMARY III. BMP EXHIBITS AND CALCULATIONS - Vicinity Map and Aerial Photo - Pre-Development Drainage Map - Post-Development Drainage Map - Pre-Development TOC Map - TOC Calculations - Run-Off Curve Number - Soils Map IV. BMP DESIGN AND CALCULATIONS V. BMP HYDROGRAGH ANALYSIS - Hydrograph Summary Report - Hydrograph Pond Report - Hydrograph Report VI. APPENDIX I. NARRATIVE T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-Ph 1 BMP Narrative.doc Page 1 of 3 VILLAGE AT GRANITE QUARRY – PHASE 1 BMP STORMWATER DESIGN NARRATIVE DPR No. 17031 November 20, 2017 Revised 12‐21‐17 Revised 3‐30‐18 Revised 6‐25‐18 The enclosed package shows the results of the stormwater BMP design calculations for Phase 1 of Village at Granite subdivision. The development is in Granite Quarry, Rowan County, North Carolina, at 3040 Faith Road. The net site area is approximately +/‐108 acres and the existing conditions consist of covered buildings with pavement, open space and woods. This project’s proposed development will be a 118 lot single‐family residential subdivision. Phase 1 has 5 proposed BMP facilities for the site, one wet pond, one dry detnetion and three sand filters. All were designed per the most recent NCDENR Stormwater design manual. Topographic maps and field observations were used to delineate the watershed basins and hydraulic path feeding into the study conveyance system. With this information, hydraulic lengths, time of concentrations (TOC), and basin slopes were determined for the pre‐developed conditions. TOC of 5 minutes was used for all post‐ developed conditions. The total impervious areas of the development were calculated. The composite curve numbers (CN) were calculated based on the hydrologic soil types and groups from the U.S. Department of Agriculture, SCS method for the pre‐developed and post‐developed conditions. Surface areas of BMPs 1‐4 were sized to handle the first‐inch of rainfall based on total impervious area of the watershed. The BMP facilities are designed to treat the 1st‐Inch of rainfall water quality volume using the Schueler simple method and to provide for channel protection using the 1‐year, 24‐hr storm. Modeling results indicate that 2‐year and 10‐year (24‐hr storm events, using SCS Method) release peak flow rates for the post‐development detention routed conditions are less than that of pre‐developed conditions. The proposed dry detention pond near Faith Road, BMP #6 is designed for detention purposes only. We have made the commitment that the future multi‐family and future commercial developments will treat the water quality/detention during that permit process. Refer to the detailed maps, calculations, results, and details as shown in this package and in the civil engineering subdivision plans. T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-Ph 1 BMP Narrative.doc Page 2 of 2 Table 1: DRAINAGE AREAS: Basin No. Drainage Area Pre‐Developed (+/‐ Ac.) Drainage Area Post‐Developed (+/‐ Ac.) Phase 1 BMP #1 5.5 5.0 Phase 1 BMP #2 9.5 9.0 Phase 1 BMP #3 16.0 22.0 Phase 1 BMP #4 5.0 4.0 Phase 1 Temp. BMP #5 2.5 ‐‐‐‐‐ Phase 1 BMP #6 5.5 6 Phase 1 Undetained Areas*4.3 5.0 TABLE 2: PRE‐DEVELOPED DISCHARGES: 1 ‐Year 2 ‐Year (cfs)10 ‐ Year (cfs) Phase 1 BMP #1 1.670 3.289 8.897 Phase 1 BMP #2 7.971 12.240 25.190 Phase 1 BMP #3 8.685 14.040 30.470 Phase 1 BMP #4 1.415 3.036 8.691 Phase 1 Temp. BMP #5 2.098 3.221 6.628 Phase 1 BMP #6 3.112 5.599 13.530 Phase 1 Undetained Areas* 1.675 3.607 10.010 TABLE 3: POST‐DEVELOPED DISCHARGES: 1 ‐Year 2 ‐Year (cfs)10 ‐ Year (cfs) Phase 1 BMP #1 11.410 15.410 26.390 Phase 1 BMP #2 22.590 29.950 49.890 Phase 1 BMP #3 50.190 67.800 116.130 Phase 1 BMP #4 7.892 10.870 19.460 Phase 1 BMP #6 7.398 11.200 22.510 Phase 1 Undetained Areas* 5.743 8.836 18.110 TABLE 4: ROUTED‐DEVELOPED DISCHARGES: 1 ‐Year 2 ‐Year (cfs)10 ‐ Year (cfs) Phase 1 BMP #1 0.204 0.278 6.437 Phase 1 BMP #2 0.255 0.503 15.770 Phase 1 BMP #3 0.411 1.514 28.610 Phase 1 BMP #4 0.163 0.241 6.751 Phase 1 BMP #6 0.256 0.910 10.200 Phase 1 Undetained Areas* 5.743 8.836 18.110 *Undetained areas include areas that are disturbed during construction but covered with grass in the final condition (5.0ac) and BUA (0.30ac) III. BMP EXHIBITS AND CALCULATIONS - Vicinity Map and Arial Photo - Pre-Development Drainage Map - Post-Development Drainage Map - Pre-Development TOC Map - TOC Calculations - Run-Off Curve Number - Impervious Calculation - Soils Map Project: Village at Granite DPR Job #: 17031 Location: Granite Quarry, NC Impervious Calculation Phase 1 Prepared by: RJ Checked by: HVN Date: Estimated Impervious Area Breakdown for Phase 1 BMP 1 Proposed 50' Wide Single Family Lots 3,210 sf x 9 lots…………………………..…………………..………………………………28,890 sq ft =0.66 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 60' Wide Single Family Lots 3,210 sf x 9 lots………………………………………………..……………………………28,890 sq ft =0.66 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 70' Wide Single Family Lots 4,060 sf x 1.75 lots……………………………………….……..……………………………7,105 sq ft =0.16 ac (avg house pad 50' x 65' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Total Proposed Lots:64,885 sq ft =1.49 ac Proposed Streets: Winding Creek Road, B/C-B/C (approx. 26' x 770 lf)…………………………………20,020 sq ft =0.46 ac Sidewalk (approx. 5' x 770lf x 2)………………………….……………………….7,700 sq ft =0.18 ac Driveway within R/W (20 x 6' x 18 lf)……………………………………………………2,160 sq ft =0.05 ac Emergency Fire Access (20' x 100 lf)……………………………………………………2,000 sq ft =0.05 ac Total Proposed Streets:31,880 sq ft =0.73 ac Total Impervious Area…………………………………………………………………….96,765 sq ft = 2.22 ac Total Net Site Area = …………………………………………….…………………………………………………..107.90 ac Phase 1 Site Area = …………………………………………….…………………………………………………..41.54 ac BMP 1 Watershed Area = ………………..…………..………………………………………………………………..5.00 ac Impervious Area Summary Imperv. Area % of Imp. Area of % of Imp. Area of % of Imp. Area of (Ac) Site Area Phase 1 Site Area BMP 1 WS Area Proprosed Lots 1.49 1.38%3.59%29.79% Prop. Amenity Area + Misc. Site Features 0.00 0.00%0.00%0.00% Proposed Streets 0.73 0.68% 1.76% 14.64% Future Muilti-Famly 0.00 0.00% 0.00% 0.00% Total Imp. Area 2.22 2.06%5.35%44.43% USED 48% IN DESIGN T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Impervious.xlsplotted: 2/27/2018 Sheet 1 of 1 Project: Village at Granite DPR Job #: 17031 Location: Granite Quarry, NC Impervious Calculation Phase 1 Prepared by: RJ Checked by: HVN Date: Estimated Impervious Area Breakdown for Phase 1 BMP 2 Proposed 50' Wide Single Family Lots 3,210 sf x 6 lots…………………………………..………………………………..19,260 sq ft =0.44 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 60' Wide Single Family Lots 3,210 sf x 0.25 lots…………………………………..………………………………..0,803 sq ft =0.02 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 70' Wide Single Family Lots 4,060 sf x 20.5 lots…………………………………..………………………………..83,230 sq ft =1.91 ac (avg house pad 50' x 65' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Total Proposed Lots:103,293 sq ft =2.37 ac Proposed Streets: Winding Creek Road, B/C-B/C (approx. 26' x 772 lf)…………………………………20,072 sq ft =0.46 ac Village Commons Drive, B/C-B/C (approx. 26' x 488 lf)………………………………12,688 sq ft =0.29 ac Sidewalk (approx. 5' x 1,260 lf x 2)………………………….……………………….12,600 sq ft =0.29 ac Driveway within R/W (23 x 6' x 18 lf)……………………………………………………2,484 sq ft =0.06 ac Emergency Fire Access (20' x 260 lf)……………………………………………………5,200 sq ft =0.12 ac Total Proposed Streets:53,044 sq ft =1.22 ac Total Impervious Area…………………………………………………………………….156,337 sq ft = 3.59 ac Total Net Site Area=…………………………………………….…………………………………………………..107.90 ac Phase 1 Site Area = …………………………………………….…………………………………………………..41.54 ac BMP 2 Watershed Area = ………………..…………..………………………………………………………………..8.50 ac Impervious Area Summary Imperv. Area % of Imp. Area of % of Imp. Area of % of Imp. Area of (Ac) Site Area Phase 1 Site Area BMP 2 WS Area Proprosed Lots 2.37 2.20%5.71%27.90% Prop. Amenity Area + Misc. Site Features 0.00 0.00%0.00%0.00% Proposed Streets 1.22 1.13% 2.93% 14.33% Future Muilti-Famly 0.00 0.00% 0.00% 0.00% Total Imp. Area 3.59 3.33%8.64%42.22% USED 48% IN DESIGN T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Impervious.xlsplotted: 2/27/2018 Sheet 1 of 1 Project: Village at Granite DPR Job #: 17031 Location: Granite Quarry, NC Impervious Calculation Phase 1 Prepared by: RJ Checked by: HVN Date: Estimated Impervious Area Breakdown for Phase 1 BMP 3 Proposed 50' Wide Single Family Lots 3,210 sf x 19.25 lots…………………………………..………………………………..61,793 sq ft =1.42 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 60' Wide Single Family Lots 3,210 sf x 16.75 lots…………………………………..………………………………..53,768 sq ft =1.23 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 70' Wide Single Family Lots 4,060 sf x 22.25 lots…………………………………..………………………………..90,335 sq ft =2.07 ac (avg house pad 50' x 65' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Total Proposed Lots:205,895 sq ft =4.73 ac Proposed Amenity Areas…………………..………………………………………… 10,000 sq ft =0.23 ac Play Ground Equipment, Metal Gazebo Pavilion Proposed Cluster Mailbox, Entry monuments, Misc ………………………………………20,000 sq ft =0.46 ac On-Street Parking (approx. 1,015 sq ft) Proposed Streets: Limestone Terrace, B/C-B/C (approx. 36' x 650 lf )……………………………………23,400 sq ft =0.54 ac Winding Creek Road, B/C-B/C (approx. 26' x 150 lf)……………………………………3,900 sq ft =0.09 ac Village Commons Drive, B/C-B/C (approx. 26' x 940 lf)………………………………24,440 sq ft =0.56 ac Standing Oak Drive, B/C-B/C (approx. 26' x 650 lf)………………..……………………16,900 sq ft =0.39 ac Trailwood Court, B/C-B/C (approx. 26' x 200 lf + 4,931 sq ft)…………………………10,131 sq ft =0.23 ac Ramses Rock Run, B/C-B/C (approx. 6,885 sq ft)………………………………………6,885 sq ft =0.16 ac Sidewalk (approx. 5' x 3,481 lf x 2)………………………….……………………….34,810 sq ft =0.80 ac Driveway within R/W (10 x 4' x 18 lf)………………………………………………………720 sq ft =0.02 ac Driveway within R/W (50 x 6' x 18 lf)………………………………………………………5,832 sq ft =0.13 ac Emergency Fire Access (20' x 225 lf)……………………………………………………4,500 sq ft =0.10 ac Total Proposed Streets:131,518 sq ft =3.02 ac Future Multi Family Site BUA = 50% Inpervious of 3.5 ac……………...…………………………………………76,230 sq ft =1.75 ac BMP 3 Premanent Water Surface Are a……………...……………………………………16,200 sq ft =0.37 ac Total Impervious Area……………………………………………………………………..459,843 sq ft = 10.56 ac Total Net Site Area=…………………………………………….…………………………………………………..107.90 ac Phase 1 Site Area = …………………………………………….…………………………………………………..41.54 ac BMP 3 Watershed Area = ………………..…………..………………………………………………………………..22.50 ac Impervious Area Summary Imperv. Area % of Imp. Area of % of Imp. Area of % of Imp. Area of (Ac) Site Area Phase 1 Site Area BMP 3 WS Area Proprosed Lots 4.73 4.38%11.38%21.01% Prop. Amenity Area + Misc. Site Features 0.69 0.64%1.66%3.06% Proposed Streets 3.02 2.80%7.27%13.42% Future Muilti-Famly 1.75 1.62%4.21%7.78% BMP 3 PWS 0.37 0.34%0.90%1.65% Total Imp. Area 10.56 9.78%25.41%46.92% USED 48% IN DESIGN T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Impervious.xlsplotted: 2/27/2018 Sheet 1 of 1 Project: Village at Granite DPR Job #: 17031 Location: Granite Quarry, NC Impervious Calculation Phase 1 Prepared by: RJ Checked by: HVN Date: Estimated Impervious Area Breakdown for Phase 1 BMP 4 Proposed 50' Wide Single Family Lots 3,210 sf x 7.75 lots…………………………………..………………………………..24,878 sq ft =0.57 ac (avg house pad 40' x 60' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Proposed 70' Wide Single Family Lots 4,060 sf x 5.5 lots…………………………………..………………………………..22,330 sq ft =0.51 ac (avg house pad 50' x 65' + 18' x 20lf Driveway + 5' x 20' sidewalk + 150 sf Patio + 200 sf Future Allocated BUA) Total Proposed Lots:47,208 sq ft =1.08 ac Proposed Streets: Standing Oak Drive, B/C-B/C (approx. 26' x 285 lf)………………..…………………7,410 sq ft =0.17 ac Sidewalk (approx. 5' x 285 lf x 2)………………………….……………………….2,850 sq ft =0.07 ac Driveway within R/W (9 x 6' x 18 lf)………………………………………………………972 sq ft =0.02 ac Total Proposed Streets:11,232 sq ft =0.26 ac Total Impervious Area…………………………………………………………………….58,440 sq ft = 1.34 ac Total Net Site Area=…………………………………………….…………………………………………………..107.90 ac Phase 1 Site Area = …………………………………………….…………………………………………………..41.54 ac BMP 4 Watershed Area = ………………..…………..………………………………………………………………..4.00 ac Impervious Area Summary Imperv. Area % of Imp. Area of % of Imp. Area of % of Imp. Area of (Ac) Site Area Phase 1 Site Area BMP 4 WS Area Proprosed Lots 1.08 1.00%2.61%27.09% Prop. Amenity Area + Misc. Site Features 0.00 0.00% 0.00% 0.00% Proposed Streets 0.26 0.24% 0.62% 6.45% Future Muilti-Famly 0.00 0.00% 0.00% 0.00% Total Imp. Area 1.34 1.24%3.23%33.54% USED 48% IN DESIGN T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Impervious.xlsplotted: 2/27/2018 Sheet 1 of 1 Project: Village at Granite DPR Job #: 17031 Location: Granite Quarry, NC Impervious Calculation Phase 1 Prepared by: RJ Checked by: HVN Date: Estimated Impervious Area Breakdown for Phase 1 BMP 6 Existing Streets: Faith Road………………..……………………………………………………………..…30,492 sq ft =0.70 ac Proposed Streets: Faith Road, B/C-B/C………………………………..……..…………………………….11,700 sq ft =0.27 ac Limestone Terrace, B/C-B/C …………………………………..……………..…………18,600 sq ft =0.43 ac Sidewalk (approx. 5' x 370 lf x 2)………………………….……………………….3,700 sq ft =0.08 ac Emergency Access #1…………………………………….…..…………………………8,000 sq ft =0.18 ac Total Proposed Streets:42,000 sq ft =0.96 ac Total Impervious Area…………………………………………………………………….72,492 sq ft = 1.66 ac Total Net Site Area=…………………………………………….…………………………………………………..107.90 ac Phase 1 Site Area = …………………………………………….…………………………………………………..41.54 ac BMP 6 Watershed Area = ………………..…………..………………………………………………………………..5.00 ac Impervious Area Summary Imperv. Area % of Imp. Area of % of Imp. Area of % of Imp. Area of (Ac) Site Area Phase 1 Site Area BMP 6 WS Area Existing Streets 0.70 0.65% 1.69% 14.00% Proposed Streets 0.96 0.89% 2.32% 19.28% Total Imp. Area 1.66 1.54%4.01%33.28% T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Impervious.xlsplotted: 8/13/2018 Sheet 1 of 1 Hydrologic Soil Group—Rowan County, North Carolina (17031-Soils) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/21/2017 Page 1 of 43940200394030039404003940500394060039407003940800394090039402003940300394040039405003940600394070039408003940900547900548000548100548200548300548400548500 548000 548100 548200 548300 548400 548500 35° 36' 38'' N 80° 28' 16'' W35° 36' 38'' N80° 27' 52'' W35° 36' 12'' N 80° 28' 16'' W35° 36' 12'' N 80° 27' 52'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84 0 150 300 600 900 Feet 0 50 100 200 300 Meters Map Scale: 1:3,890 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Rowan County, North Carolina Survey Area Data: Version 13, Sep 20, 2016 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 14, 2015—Mar 15, 2017 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—Rowan County, North Carolina (17031-Soils) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/21/2017 Page 2 of 4 Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — Rowan County, North Carolina (NC159) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI CcB Cecil sandy loam, 2 to 8 percent slopes B 2.5 5.7% CeB2 Cecil sandy clay loam, 2 to 8 percent slopes, moderately eroded B 10.1 23.0% ChA Chewacla loam, 0 to 2 percent slopes, frequently flooded B/D 0.4 0.8% VnB2 Vance sandy clay loam, 2 to 8 percent slopes, moderately eroded C 19.2 43.7% VnC2 Vance sandy clay loam, 8 to 15 percent slopes, moderately eroded C 11.8 26.8% Totals for Area of Interest 43.9 100.0% Hydrologic Soil Group—Rowan County, North Carolina 17031-Soils Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/21/2017 Page 3 of 4 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Rowan County, North Carolina 17031-Soils Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/21/2017 Page 4 of 4 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-171Total Drain. Area (Ac.)5.50Site Soil TypeSoil GroupPercentage of BasinCeB2B1.0 ac18.2%VnB2, VnC2C4.0 ac72.7%5.0 ac90.9%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.509.1%5510.0660.07050.9 60.9 5.5Open Space - Grass and Shurbs (Good Cond.)5.0090.9%6111.1710.07453.8 64.9 59.0Impervious0.000.0%9817.8980.09871.3 89.1 0.064.5Total5.5100%Composite Curve Number (CN):651Total Drain. Area (Ac.)5.00Site Soil TypeSoil GroupPercentage of BasinCeB2B1.0 ac20.0%VnB2, VnC2C4.0 ac80.0%5.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%5511.0660.07056.0 67.0 0.0Open Space - Grass and Shurbs (Good Cond.)2.6052.0%6112.2710.07459.2 71.4 37.1Impervious2.4048.0%9819.6980.09878.4 98.0 47.084.2Total5.0100%Composite Curve Number (CN):84Existing Condition Watershed BMP #Proposed Development Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 6 3/30/2018 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-172Total Drain. Area (Ac.)9.50Site Soil TypeSoil GroupPercentage of BasinVnB2, VnC2C9.5 ac100.0%9.5 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)4.0042.1%550.0660.07070.0 70.0 29.5Open Space - Grass and Shurbs (Good Cond.)5.0052.6%610.0710.07474.0 74.0 38.9Impervious0.505.3%980.0980.09898.0 98.0 5.273.6Total9.5100%Composite Curve Number (CN):742Total Drain. Area (Ac.)9.00Site Soil TypeSoil GroupPercentage of BasinVnB2, VnC2C9.0 ac100.0%9.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%550.0660.07070.0 70.0 0.0Open Space - Grass and Shurbs (Good Cond.)4.6852.0%610.0710.07474.0 74.0 38.5Impervious4.3248.0%980.0980.09898.0 98.0 47.085.5Total9.0100%Composite Curve Number (CN):86Existing Condition Watershed BMP #Proposed Development Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 1 6/22/2018 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-173Total Drain. Area (Ac.)16.00Site Soil TypeSoil GroupPercentage of BasinCcB, CeB2B3.0 ac18.8%ChAB/D1.0 ac6.3%VnB2, VnC2C12.0 ac75.0%16.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)1.408.8%5510.3664.17052.5 66.9 5.9Open Space - Grass and Shurbs (Good Cond.)13.4083.8%6111.4714.47455.5 71.4 59.8Impervious1.106.9%9818.4986.19873.5 98.0 6.772.4Total15.999%Composite Curve Number (CN):723Total Drain. Area (Ac.)22.00Site Soil TypeSoil GroupPercentage of BasinCcB, CeB2B3.9 ac17.7%ChAB/D0.3 ac1.4%VnB2, VnC2C17.8 ac80.9%22.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%559.8660.97056.6 67.3 0.0Open Space - Grass and Shurbs (Good Cond.)11.4452.0%6110.8711.07459.9 71.7 37.3Impervious10.5648.0%9817.4981.39879.3 98.0 47.084.3Total22.0100%Composite Curve Number (CN):84Existing Condition Watershed BMP #Proposed Development Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 1 6/22/2018 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-174Total Drain. Area (Ac.)5.00Site Soil TypeSoil GroupPercentage of BasinCcB, CeB2B2.6 ac52.0%ChAB/D0.4 ac8.0%VnB2, VnC2C2.0 ac40.0%5.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)3.5070.0%5528.6665.37028.0 61.9 43.3Open Space - Grass and Shurbs (Good Cond.)1.5030.0%6131.7715.77429.6 67.0 20.1Impervious0.000.0%9851.0987.89839.2 98.0 0.063.4Total5.0100%Composite Curve Number (CN):634Total Drain. Area (Ac.)4.00Site Soil TypeSoil GroupPercentage of BasinCcB, CeB2B2.5 ac62.5%ChAB/D0.3 ac7.5%VnB2, VnC2C1.2 ac30.0%4.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%5534.4665.07021.0 60.3 0.0Open Space - Grass and Shurbs (Good Cond.)2.0852.0%6138.1715.37422.2 65.7 34.1Impervious1.9248.0%9861.3987.49829.4 98.0 47.081.2Total4.0100%Composite Curve Number (CN):81Existing Condition Watershed BMP #Proposed Development Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 4 of 6 3/30/2018 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-175Total Drain. Area (Ac.)2.50Site Soil TypeSoil GroupPercentage of BasinCcB, CeB2B0.0 ac0.0%ChAB/D0.0 ac0.0%VnB2, VnC2C2.5 ac100.0%2.5 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%550.0660.07070.0 70.0 0.0Open Space - Grass and Shurbs (Good Cond.)2.50100.0%610.0710.07474.0 74.0 74.0Impervious0.000.0%980.0980.09898.0 98.0 0.074.0Total2.5100%Composite Curve Number (CN):74Existing Condition Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 5 of 6 3/30/2018 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-176Total Drain. Area (Ac.)5.50Site Soil TypeSoil GroupPercentage of BasinCeB2B4.3 ac78.2%ChAB/D0.0 ac0.0%VnB2, VnC2C1.2 ac21.8%5.5 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.0%5543.0660.07015.3 58.3 0.0Open Space - Grass and Shurbs (Good Cond.)5.0090.9%6147.7710.07416.1 63.8 58.0Impervious0.509.1%9876.6980.09821.4 98.0 8.966.9Total5.5100%Composite Curve Number (CN):66.96Total Drain. Area (Ac.)6.00Site Soil TypeSoil GroupPercentage of BasinCeB2B4.8 ac80.0%ChAB/D0.0 ac0.0%VnB2, VnC2C1.2 ac20.0%6.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%5544.0660.07014.0 58.0 0.0Open Space - Grass and Shurbs (Good Cond.)4.4073.3%6148.8710.07414.8 63.6 46.6Impervious1.6026.7%9878.4980.09819.6 98.0 26.172.8Total6.0100%Composite Curve Number (CN):73Existing Condition Watershed BMP #Proposed Development Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 1 8/13/2018 Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-17Total Drain. Area (Ac.)4.30Site Soil TypeSoil GroupPercentage of BasinCeB2B3.0 ac69.8%ChAB/D0.0 ac0.0%VnB2, VnC2C1.3 ac30.2%4.3 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)3.0069.8%5538.4660.07021.2 59.5 41.5Open Space - Grass and Shurbs (Good Cond.)1.2027.9%6142.6710.07422.4 64.9 18.1Impervious0.102.3%9868.4980.09829.6 98.0 2.361.9Total4.3100%Composite Curve Number (CN):61.9Total Drain. Area (Ac.)5.00Site Soil TypeSoil GroupPercentage of BasinCeB2B1.0 ac20.0%ChAB/D2.6 ac52.0%VnB2, VnC2C1.4 ac28.0%5.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%5511.06634.37019.6 64.9 0.0Open Space - Grass and Shurbs (Good Cond.)4.7094.0%6112.27136.97420.7 69.8 65.6Impervious0.306.0%9819.69851.09827.4 98.0 5.971.5Total5.0100%Composite Curve Number (CN):72Existing Condition Undetain AreaProposed Development Undetain AreaT:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 1 8/13/2018 Project: Village at Granite DPR Job No.: 17031 Location: Granite Quarry, NC Sheet: 1 of 4 DPR ASSOCIATES TIME OF CONCENTRATION BMP 1 Prepared by:RJ Checked by:HN Date: 11-17-17 EXISTING CONDITION - TIME OF CONCENTRATION (BMP #1) SHEET FLOW: Surface Description = grass Manning's Roughness (n) = 0.24 Flow Length (ft) = 150 Slope (%) = 2.0 P-2yr (in.) = 3.12 T(t) (min.) =20.0 SHALLOW CONCENTRATED FLOW: Surface Description unpaved Flow Length (ft) =470 Water Course Slope (%) = 6.00 Average Velocity (fps) =3.95 T(t) (min.) =2.0 T(t) Sum of Travel Time (min)= 22.0 Time =22 (min.) Hydraulic Length = 620 ft Basin Slope = 5.0 POST DEVELOPMENT - TIME OF CONCENTRATION Time =5 (min.) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-TOCPlotted 12/21/2017 Sheet: 1 of 1 Project: Village at Granite DPR Job No.: 17031 Location: Granite Quarry, NC Page: 2 of 4 DPR ASSOCIATES TIME OF CONCENTRATION BMP 2 Prepared by: RJ Checked by: HN Date: 11-17-17 EXISTING CONDITION - TIME OF CONCENTRATION (BMP #2) SHEET FLOW: Surface Description = grass Manning's Roughness (n) = 0.24 Flow Length (ft) = 150 Slope (%) = 4.0 P-2yr (in.) = 3.12 T(t) (min.) =15.1 SHALLOW CONCENTRATED FLOW: Surface Description unpaved Flow Length (ft) =430 Water Course Slope (%) = 7.00 Average Velocity (fps) =4.27 T(t) (min.) =1.7 CHANNEL FLOW: Average Channel Area (sf) =4.00 Bottom Width (ft) = 2 Hydraulic Radius =0.618 Side Slope (X:1) = 2 Flow Length (ft) =235 Channel Slope (%) = 2 Depth (ft) =1 Manning's Coefficient (n) = 0.048 Velocity (fps) =3.19 T(t) (min.) =1.2 T(t) Sum of Travel Time (min)= 18.1 Time =18 (min.) Hydraulic Length = 815 ft Basin Slope = 5.0 POST DEVELOPMENT - TIME OF CONCENTRATION Time =5 (min.) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-TOCPlotted 12/21/2017 Sheet: 1 of 1 Project: Village at Granite DPR Job No.: 17031 Location: Granite Quarry, NC Sheet: 3 of 4 DPR ASSOCIATES TIME OF CONCENTRATION BMP 3 Prepared by: RJ Checked by: HN Date: 11-17-17 EXISTING CONDITION - TIME OF CONCENTRATION (BMP #3) SHEET FLOW: Surface Description = grass Manning's Roughness (n) = 0.24 Flow Length (ft) = 150 Slope (%) = 2.0 P-2yr (in.) = 3.12 T(t) (min.) =20.0 SHALLOW CONCENTRATED FLOW: Surface Description unpaved Flow Length (ft) =1180 Water Course Slope (%) = 3.50 Average Velocity (fps) =3.02 T(t) (min.) =6.5 T(t) Sum of Travel Time (min)= 26.5 Time =27 (min.) Hydraulic Length = 1330 ft Basin Slope = 3.3 POST DEVELOPMENT - TIME OF CONCENTRATION Time =5 (min.) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-TOCPlotted 12/21/2017 Sheet: 1 of 1 Project: Village at Granite DPR Job No.: 17031 Location: Granite Quarry, NC Sheet: 4 of 4 DPR ASSOCIATES TIME OF CONCENTRATION BMP 4 Prepared by: RJ Checked by: HN Date:10-17-17 EXISTING CONDITION - TIME OF CONCENTRATION (BMP #4) SHEET FLOW: Surface Description = grass Manning's Roughness (n) = 0.24 Flow Length (ft) = 150 Slope (%) = 6.7 P-2yr (in.) = 3.12 T(t) (min.) =12.3 SHALLOW CONCENTRATED FLOW: Surface Description unpaved Flow Length (ft) = 635 Water Course Slope (%) = 5.00 Average Velocity (fps) =3.61 T(t) (min.) =2.9 T(t) Sum of Travel Time (min)= 15.3 Time =15 (min.) Hydraulic Length = 785 ft Basin Slope = 5.3 POST DEVELOPMENT - TIME OF CONCENTRATION Time =5 (min.) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-TOC.xlsPlotted 3/30/2018 Sheet: 1 of 1 Project: Sample DPR Job No.: 00000.0 Location: Mecklenburg Co. DPR ASSOCIATES BMP (Charlotte-Meck. Storm Water Design Manual) Prepared by:XXX Checked by:XXX Date:X-XX-XX EXISTING CONDITION - TIME OF CONCENTRATION (BMP #5) SHEET FLOW: Surface Description = grass Manning's Roughness (n) = 0.24 Flow Length (ft) = 150 Slope (%) = 3.0 P-2yr (in.) = 3.12 T(t) (min.) =17.0 SHALLOW CONCENTRATED FLOW: Surface Description unpaved Flow Length (ft) = 130 Water Course Slope (%) = 3.00 Average Velocity (fps) =2.79 T(t) (min.) =0.8 T(t) Sum of Travel Time (min)= 17.8 Time =18 (min.) Hydraulic Length = 280 ft Basin Slope = 3.0 T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-TOC.xlsPlotted 3/30/2018 Sheet: 1 of 1 Project: Village at Granite DPR Job No.: 17031 Location: Granite Quarry, NC DPR ASSOCIATES TIME OF CONCENTRATION Prepared by: RJ Checked by: HN Date: 4-18-18 EXISTING CONDITION - TIME OF CONCENTRATION (BMP #6) SHEET FLOW: Surface Description = grass Manning's Roughness (n) = 0.24 Flow Length (ft) = 100 Slope (%) = 5.5 P-2yr (in.) = 3.12 T(t) (min.) =9.6 CHANNEL FLOW: Average Channel Area (sf) =4.00 Bottom Width (ft) = 2 Hydraulic Radius =0.618 Side Slope (X:1) = 2 Flow Length (ft) = 315 Channel Slope (%) = 2 Depth (ft) = 1 Manning's Coefficient (n) = 0.048 Velocity (fps) =3.19 T(t) (min.) =1.6 CHANNEL FLOW: Average Channel Area (sf) =4.00 Bottom Width (ft) = 2 Hydraulic Radius =0.618 Side Slope (X:1) = 2 Flow Length (ft) = 148 Channel Slope (%) = 2 Depth (ft) = 1 Manning's Coefficient (n) = 0.048 Velocity (fps) =3.19 T(t) (min.) =0.8 T(t) Sum of Travel Time (min)= 12.1 Time =12 (min.) Hydraulic Length = 563 ft Basin Slope = 2.4 POST DEVELOPMENT - TIME OF CONCENTRATION Time =5 (min.) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-TOC.xlsPlotted 8/13/2018 Sheet: 1 of 1 IV. BMP DESIGN AND CALCULATIONS Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 1 of 3 DPR ASSOCIATES, INC SAND FILTER-1 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 12-21-17 DESIGN CRITERIA PER NCDENR STORMWATER DESIGN MANUAL DATED JAN 2017 * BMP - SAND FILTER - WATER QUALITY CONTROL ONLY 1 * Total Drainage Area (A):5.00 ac * Total Impervious Area "I" USED = 2.40 ac (See attached Impervious Calcs) * Total Water Quality Volume To Treat (First 1" of Rainfall): WQv = (P/12) (A) (Rv) (43560) =8,748 cf (Simple Method, Schueler) P: Water Quality Design Storm, 1st Inch of Rainfall 1 inch A: Drainage Area (Impervious Area Only) 5.00 ac. Rv: 0.05 + 0.009 (I) = 0.482 I: % of Impervious Area 48.0% * Total Storm Water Volume Control 1-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =24,564 cf (SCS Method) P: Design Storm, 1-yr 24-hr Storm Rainfall depth 2.80 inch A: Drainage Area 5.00 ac. S = 1,000/CN-10 =1.90 inch CN: Curve Number 84 * Estimated Storm Water Volume 10-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =34,526 cf (SCS Method) P: Design Storm, 10-yr 24-hr Storm Rainfall depth 3.46 inch A: Drainage Area 5.00 ac. S = 1000/CN-10 =1.90 inch CN: Curve Number 84 * Sedimentation Chamber Volume Min. Required: Vol-Pre = (0.2)(WQv) =1,750 cf * Sedimentation Chamber Volume Provided:9,200 cf * Filtration Media Surface Area Required: Af=[(WQv) (Df)]/ [(k) (Hf + Df) (Tf)] =949 sf (From Mecklenburg BMP Manual, Based on Darcy's Law) WQv: Water quality volume 8,748 cf Df: Filter bed depth (2'.5 for Optimal Efficiency)2.5 ft k: Permeability coefficient of filter media 3.50 ft/day (1.75" per hour, or 3.5' per day) Hf: Average height of water above filter bed, (half of pond depth, 1' max)0.60 ft Tf = Design filter bed drain time in days, (2 days beyond center 6-hr storm)2.125 days Depth of Pond Water (24" Max.)=24 inch * Filtration Media Surface Area Provided:1,000 sf BMP Storage Volume Provided: Elevation Surface Area Storage Total Storage (ft) (sf) (cf) (cf) 729.5 Bottom of Stone - Provide liner per geo recommendation 730.5 Top of Stone/Bottom of Sand 733.0 Top of Sand Filter/ Bottom of Extended Dry Detention Pond 733.0 6,700 00Bottom of Pond 734.0 7,800 7,250 7,250 736.0 10,100 17,900 25,150 737.5 12,000 16,575 41,725 Top of Embankment Static Water Quality Elevation @ 734.21 ft Static Channel Protection Elevation @ 735.93 ft 48.0% (for Design) SHWTE and groundwater @ 733.86' per Summit Geo Report letter dated 11-14-17 FEMA 100 Year Flood Elevation @ 727.8' (Flood Insurance Study dated 6-16-2009) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 1 of 3 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 2 of 3 DPR ASSOCIATES, INC SAND FILTER-1 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 12-21-17 * BMP - SAND FILTER 1 * Water Draw Down Flow Rate Thru Sand Filter Media Qo = WQv / Tf = (Af)(k)(Hf+Df)/Df = 0.0692 cfs (Darcy's Law) k: Permeability coefficient of filter media 3.50 ft/day Af: Surface area, sf 949 sf Hf: Average height of water above filter bed 2.00 ft Df: Depth of soil filter bed 2.5 ft Q O @ Top of Media 733.0 = 0.0000 cfs Q O @ Median of WQv storage 733.6 =0.0506 cfs Q O @ Top of WQv storage 734.2 =0.0620 cfs * Time Drawdown from Inundation to Saturation surface Tf = WQv / Qo 35.13 hrs * Sizing Under Drain Pipes Q: Draw down rate thru sand filter 0.0692 cfs Use [2]-17 lf of 6" PVC or Sch 40, Use 2 of w/ 3/8" perforations spaced 3" on center, 4 rows w/ 90-deg apart 17 LF of 6 inch # of Perforation = (# pipes)(4 rows/ft) (Linear feet/per pipe -2') (4 holes/row) = (2 pipes)(4)(17 lf)(4)20 holes Capacity of one hole (3/8") = CA(2gh)^(0.5)(orifice equation)0.0078 cfs c= Discharge Coefficient 0.6 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) of 3/8" hole 0.0008 h= head above perforation 4.5 Total Capacity = Capacity of 1 hole x # of holes 0.1566 cfs Total Capacity w/ 50% lost to clogging 0.0783 cfs Underdrain Pipe Capacity= 1.49/n(A)(A/P)^(2/3) (S)^0.5 (Manning Eq)0.395 cfs n= pipe coefficient 0.013 A= Area (sf) of 6" dia pipe 0.1963 P= Pipe Perimeter, ft 1.57 s= slope, 0.5% 0.005 Underdrain Pipe Capacity w/ 50% lost to clogging 0.1974 cfs Both Flow Rates thru Perforation and Pipe are greater than that of Flow rate of Sand Filter. OK * Orifice Calcs For Channel Protection Dewatering Time 2 days (48 hrs) Beyond Center of 24-hr Storm (Sized for the Volume of 1-yr Storm with 50% remained at 36th Hour, 5% remained at 60th Hour, and drained completely at 120th Hour). 1-yr Storm Volume, Less 50% Remain Beyond 36th Hour 12,282 cf Average Surface Area 4,192 sf Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) a = 0.023 where: A= Resevoir Area, sf 4,192 Max. Orifice Diameter (inch), d = 2.04 h= Falling Head, ft 2.83 c= Discharge Coefficient 0.6 Orifice Diameter (inch) Used, d =2.5 t= Time ( 36 hrs), sec.129,600 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) * 1-yr Storm CPv Draw Down Flow Rate Thru Sand Media Qo = WQv / Tf 0.1137 cfs (Darcy's Law) CPv: 1-yr Storm Volume 24,564 cf Tf: 2 days beyond center of 24hr-storm, 60 hours 216,000 sec T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 2 of 3 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 3 of 3 DPR ASSOCIATES, INC SAND FILTER-1 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 12-21-17 * BMP - SAND FILTER 1 Anti-Seep Collar Sizing Outlet Pipe Size (I.D.) = 18 in Outlet Pipe Size (O.D.) = 1.92 ft L, Length of Outlet Pipe = 40 lf Min. Flow Length = 46.0 ft Min. Flow Length = 115% of outlet pipe Total Lengh of Collar offset = 6.0 ft Number of anti-seep collars 2 Offset per collar 3.0 ft Min. Outside dimension of each collar 4.92 ft Designed collars 2 at 5.0' x 5.0' T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 3 of 3 Pond Report 17 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v12 Monday, 08 / 13 / 2018 Pond No. 1 - PH1 BMP 1 - SANDFILTER Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 733.00 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 733.00 6,700 0 0 1.00 734.00 7,800 7,250 7,250 3.00 736.00 10,100 17,900 25,150 4.50 737.50 12,000 16,575 41,725 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)= 18.00 3.00 6.00 0.00 Span (in)= 18.00 3.00 160.00 0.00 No. Barrels = 1 110 Invert El. (ft)= 728.35 734.10 736.00 0.00 Length (ft)= 66.00 0.50 0.50 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a Yes Yes No Crest Len (ft)= 10.00 0.00 0.00 0.00 Crest El. (ft)= 736.50 0.00 0.00 0.00 Weir Coeff.= 2.60 3.33 3.33 3.33 Weir Type = Broad --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 Stage (ft) 0.00 733.00 1.00 734.00 2.00 735.00 3.00 736.00 4.00 737.00 5.00 738.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 1 of 3 DPR ASSOCIATES, INC SAND FILTER-2 DESIGN Prepared By: RJ Checked By: HN Date: 11-17-17 Revised: 12-21-17 DESIGN CRITERIA PER NCDENR STORMWATER DESIGN MANUAL DATED JAN 2017 * BMP - SAND FILTER - WATER QUALITY CONTROL ONLY 2 * Total Drainage Area (A):9.00 ac * Total Impervious Area "I" USED = 4.32 ac (See attached Impervious Calcs) * Total Water Quality Volume To Treat (First 1" of Rainfall): WQv = (P/12) (A) (Rv) (43560) =15,747 cf (Simple Method, Schueler) P: Water Quality Design Storm, 1st Inch of Rainfall 1 inch A: Drainage Area (Impervious Area Only) 9.00 ac. Rv: 0.05 + 0.009 (I) = 0.482 I: % of Impervious Area 48.0% * Total Storm Water Volume Control 1-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =48,760 cf (SCS Method) P: Design Storm, 1-yr 24-hr Storm Rainfall depth 2.8 inch A: Drainage Area 9.00 ac. S = 1,000/CN-10 =1.63 inch CN: Curve Number 86 * Estimated Storm Water Volume 10-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =67,398 cf (SCS Method) P: Design Storm, 10-yr 24-hr Storm Rainfall depth 3.46 inch A: Drainage Area 9.00 ac. S = 1000/CN-10 =1.63 inch CN: Curve Number 86 * Sedimentation Chamber Volume Min. Required: Vol-Pre = (0.2)(WQv) =3,149 cf * Sedimentation Chamber Volume Provided:13,000 cf * Filtration Media Surface Area Required: Af=[(WQv) (Df)]/ [(k) (Hf + Df) (Tf)] =1,616 sf (From Mecklenburg BMP Manual, Based on Darcy's Law) WQv: Water quality volume 15,747 cf Df: Filter bed depth (2'.5 for Optimal Efficiency)2.5 ft k: Permeability coefficient of filter media 3.50 ft/day (1.75" per hour, or 3.5' per day) Hf: Average height of water above filter bed, (half of pond depth, 1' max)0.78 ft Tf = Design filter bed drain time in days, (2 days beyond center 6-hr storm)2.125 days Depth of Pond Water (24" Max.)=24 inch * Filtration Media Surface Area Provided:2,000 sf BMP Storage Volume Provided: Elevation Surface Area Incremental Storage Total Storage (ft) (sf) (cf) (cf) 724.5 Bottom of Stone 725.5 Top of Stone/Bottom of Sand 728.0 Top of Sand Filter/ Bottom of Extended Dry Detention Pond 728.0 5,300 00Bottom of Pond 730.0 13,500 18,800 18,800 732.0 17,100 30,600 49,400 734.0 20,900 38,000 87,400 Top of Embankment Static Water Quality Elevation @ 729.68 ft Static Channel Protection Elevation @ 731.96 ft 48.0% (for Design) SHWTE and groundwater @ 719.73' per Summit Geo Report letter dated 11-14-17 FEMA 100 Year Flood Elevation @ 725.0' (Flood Insurance Study dated 6-16-2009) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 1 of 3 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 2 of 3 DPR ASSOCIATES, INC SAND FILTER-2 DESIGN Prepared By: RJ Checked By: HN Date: 11-17-17 Revised: 12-21-17 * BMP - SAND FILTER 2 * Water Draw Down Flow Rate Thru Sand Filter Media Qo = WQv / Tf = (Af)(k)(Hf+Df)/Df = 0.1178 cfs (Darcy's Law) k: Permeability coefficient of filter media 3.50 ft/day Af: Surface area, sf 1,616 sf Hf: Average height of water above filter bed 2.00 ft Df: Depth of soil filter bed 2.5 ft Q O @ Top of Media 728.0 = 0.0000 cfs Q O @ Median of WQv storage 728.8 =0.0506 cfs Q O @ Top of WQv storage 729.7 =0.0620 cfs * Time Drawdown from Inundation to Saturation surface Tf = WQv / Qo 37.12 hrs * Sizing Under Drain Pipes Q: Draw down rate thru sand filter 0.1178 cfs Use [2]-17 lf of 6" PVC or Sch 40, Use 2 of w/ 3/8" perforations spaced 3" on center, 4 rows w/ 90-deg apart 17 LF of 6 inch # of Perforation = (# pipes)(4 rows/ft) (Linear feet/per pipe -2') (4 holes/row) = (2 pipes)(4)(17 lf)(4)20 holes Capacity of one hole (3/8") = CA(2gh)^(0.5)(orifice equation)0.0078 cfs c= Discharge Coefficient 0.6 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) of 3/8" hole 0.0008 h= head above perforation 4.5 Total Capacity = Capacity of 1 hole x # of holes 0.1566 cfs Total Capacity w/ 50% lost to clogging 0.0783 cfs Underdrain Pipe Capacity= 1.49/n(A)(A/P)^(2/3) (S)^0.5 (Manning Eq)0.395 cfs n= pipe coefficient 0.013 A= Area (sf) of 6" dia pipe 0.1963 P= Pipe Perimeter, ft 1.57 s= slope, 0.5% 0.005 Underdrain Pipe Capacity w/ 50% lost to clogging 0.1974 cfs Both Flow Rates thru Perforation and Pipe are greater than that of Flow rate of Sand Filter. OK * Orifice Calcs For Channel Protection Dewatering Time 2 days (48 hrs) Beyond Center of 24-hr Storm (Sized for the Volume of 1-yr Storm with 50% remained at 36th Hour, 5% remained at 60th Hour, and drained completely at 120th Hour). yr Storm Volume, Less 50% Remain Beyond 36th Hour 24,380 cf Average Surface Area 14,512 sf Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) a = 0.058 where: A= Resevoir Area, sf 14,512 Max. Orifice Diameter (inch), d = 3.28 h= Falling Head, ft 1.58 c= Discharge Coefficient 0.6 Orifice Diameter (inch) Used, d =2.5 t= Time ( 36 hrs ), sec.129,600 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) * 1-yr Storm CPv Draw Down Flow Rate Thru Sand Media Qo = WQv / Tf 0.2257 cfs (Darcy's Law) CPv: 1-yr Storm Volume 48,760 cf Tf: 2 days beyond center of 24hr-storm, 60 hours 216,000 sec T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 2 of 3 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 3 of 3 DPR ASSOCIATES, INC SAND FILTER-2 DESIGN Prepared By: RJ Checked By: HN Date: 11-17-17 Revised: 12-21-17 * BMP - SAND FILTER 2 Anti-Seep Collar Sizing Outlet Pipe Size (I.D.) = 36 in Outlet Pipe Size (O.D.) = 3.67 ft L, Length of Outlet Pipe = 38 lf Min. Flow Length = 43.7 ft Min. Flow Length = 115% of outlet pipe Total Lengh of Collar offset = 5.7 ft Number of anti-seep collars 2 Offset per collar 2.9 ft Min. Outside dimension of each collar 6.52 ft Designed collars 2 at 6.5' x 6.5' T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 3 of 3 Pond Report 19 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v12 Monday, 08 / 13 / 2018 Pond No. 2 - PH1 BMP 2 - SANDFILTER Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 728.00 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 728.00 5,300 0 0 2.00 730.00 13,500 18,800 18,800 4.00 732.00 17,100 30,600 49,400 6.00 734.00 20,900 38,000 87,400 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)= 36.00 3.00 6.00 0.00 Span (in)= 36.00 3.00 204.00 0.00 No. Barrels = 1 110 Invert El. (ft)= 724.33 729.80 731.80 0.00 Length (ft)= 32.00 0.50 0.50 0.00 Slope (%)= 1.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a Yes Yes No Crest Len (ft)= 0.00 0.00 0.00 0.00 Crest El. (ft)= 0.00 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = --- --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 6.00 12.00 18.00 24.00 30.00 36.00 42.00 48.00 54.00 60.00 Stage (ft) 0.00 728.00 1.00 729.00 2.00 730.00 3.00 731.00 4.00 732.00 5.00 733.00 6.00 734.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Project: Village at Granite - Phase1 Job No.: 17031 Location: Granite Quarry, NC Sheet: 1 of 2 DPR ASSOCIATES BMP WETPOND #3 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 2-26-18, RJ DESIGN CRITERIA PER NCDENR STORMWATER DESIGN MANUAL DATED JAN 2017 * BMP WET DETENTION POND 3 * Total Drainage Area (A):22.00 ac * Total Impervious Area "I" USED = 10.56 ac (See attached Impervious Calcs) * Total Water Quality Volume To Treat (First 1" of Rainfall): WQv = (P/12) (A) (Rv) (43,560) =38,493 cf (Simple Method, Schueler) P: Water Quality Design Storm, 1st 1-Inch of Rainfall 1 inch A: Drainage Area 22.00 ac. Rv: 0.05 + 0.009 (I) = 0.482 I: % of Impervious Area 48.0% * Main Pool: Pool Average Depth (H)=6.5 ft Surface Area to Drainage Area Ratio (SA/DA)= (NCDENR Table 1 )1.04 Required Surface Area (SA)=9,967 sf Provided Surface Area (SA) @ Perm. W.S. Elev.=18,000 sf Required Pool Volume (V= SA*H)=64,782 cf Provided Pool Volume (V) @ Perm. W.S. Elev.=74,500 cf * Forebay: Required Forebay Volume (20% of Pool Volume)=12,956 cf Provided Forbay Volume @ Perm. W.S. Elev.=13,000 cf * Estimated Storm Water Volume 1-yr, 24-hr Post-Dev:108,082 cf Qv = (P-0.2S)^2/ (P+0.8S) * A * (43,560/12) = (SCS Method) P: Design Storm, 1-yr 24-hr Storm Rainfall depth 2.8 inch A: Drainage Area 22.00 ac. S = 1000/CN-10 =1.90 inch CN: Curve Number 84 * Estimated Storm Water Volume 10-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43,560/12) =151,915 cf (SCS Method) P: Design Storm, 10-yr 24-hr Storm Rainfall depth 3.46 inch A: Drainage Area 22.00 ac. S = 1000/CN-10 =1.90 inch CN: Curve Number 84 BMP Pond Storage Volume Provided: Stage Surface Area Incremental Storage Total Storage (ft) (sf) (cf) (cf) Notes 716.0 2,000 0 0 Bottom of Pond 718.0 11,300 13,300 13,300 720.0 13,200 24,500 37,800 722.0 15,200 28,400 66,200 722.5 (Perm. W.S.) 18,000 8,300 74,500 Top of Perm. Pool 722.5 (Perm. W.S.) 18,000 0 0 Bottom of Temp. Pool 723.0 21,400 9,850 9,850 724.0 23,500 22,450 32,300 724.5 24,600 12,025 44,325 726.0 27,900 39,375 83,700 728.0 32,400 60,300 144,000 729.0 34,800 33,600 177,600 729.5 36,200 17,750 195,350 Top of Embankment Static Water Quality Elevation @ 724.26 ft Static Channel Protection Elevation @ 726.81 ft 48.0% (for Design) SHWTE and groundwater @ 722.28' per Summit Geo Report letter dated 11-14-17 FEMA 100 Year Flood Elevation @ 724.14' (DPR Flood Study dated 6-1-2018) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Wet Pond.xls printed 8/13/2018 Project: Village at Granite - Phase1 Job No.: 17031 Location: Granite Quarry, NC Sheet: 2 of 2 DPR ASSOCIATES BMP WETPOND #3 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 2-26-18, RJ * BMP POND 3 * Orifice Calculations For Detawering Time Between 24 hrs to 120 hrs WQv 38,493 cf Average Surface Area 21,871 sf Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) a =0.084 where: A= Resevoir Area, sf 21,871 Min. Orifice Diameter (inch), d =3.93 h= Falling Head, ft 1.76 c= Discharge Coefficient 0.5 Orifice Diameter (inch) Used, d =3.0 t= Time (48 Hrs), sec. 172,800 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) Emergency Drain Orifice Calculations For Permanent Pond Within 24 hrs Permanent Pool Volume 74,500 cf Average Surface Area 11,462 sf Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) a =0.169 where: A= Resevoir Area, sf 11,462 Min. Orifice Diameter (inch), d =5.58 h= Falling Head, ft 6.50 c= Discharge Coefficient 0.5 Orifice Diameter (inch) Used, d =5.0 t= Time (24 Hrs), sec. 86,400 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) Anti-Seep Collar Sizing Outlet Pipe Size (I.D.) = 36 in Outlet Pipe Size (O.D.) = 3.67 ft L, Length of Outlet Pipe = 96 lf Min. Flow Length = 110.4 ft Min. Flow Length = 115% of outlet pipe length Total Lengh of Collar offset = 14.4 ft Number of anti-seep collars 2 Offset per collar 7.2 ft Min. Outside dimension of each collar 10.87 ft Designed collars 2 at 10' x 10' T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Wet Pond.xls printed 8/13/2018 Pond Report 21 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v12 Monday, 08 / 13 / 2018 Pond No. 3 - PH1 BMP 3 - WET POND Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 722.50 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 722.50 18,000 0 0 0.50 723.00 21,400 9,850 9,850 1.50 724.00 23,500 22,450 32,300 2.00 724.50 24,600 12,025 44,325 3.50 726.00 27,900 39,375 83,700 5.50 728.00 32,400 60,300 144,000 6.50 729.00 34,800 33,600 177,600 7.00 729.50 36,200 17,750 195,350 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)= 36.00 3.00 6.00 0.00 Span (in)= 36.00 3.00 204.00 0.00 No. Barrels = 1 110 Invert El. (ft)= 719.45 722.50 726.50 0.00 Length (ft)= 90.00 0.50 0.50 0.00 Slope (%)= 0.50 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a Yes Yes No Crest Len (ft)= 10.00 0.00 0.00 0.00 Crest El. (ft)= 728.00 0.00 0.00 0.00 Weir Coeff.= 2.60 3.33 3.33 3.33 Weir Type = Broad --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Contour) TW Elev. (ft)= 723.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 Stage (ft) 0.00 722.50 2.00 724.50 4.00 726.50 6.00 728.50 8.00 730.50 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 1 of 3 DPR ASSOCIATES, INC SAND FILTER-4 DESIGN Prepared By: RJ Checked By: HN Date: 11-17-17 Revised 12-21-17 DESIGN CRITERIA PER NCDENR STORMWATER DESIGN MANUAL DATED JAN 2017 * BMP - SAND FILTER - WATER QUALITY CONTROL ONLY 4 * Total Drainage Area (A):4.00 ac * Total Impervious Area "I" USED = 1.92 ac (See attached Impervious Calcs) * Total Water Quality Volume To Treat (First 1" of Rainfall): WQv = (P/12) (A) (Rv) (43560) =6,999 cf (Simple Method, Schueler) P: Water Quality Design Storm, 1st Inch of Rainfall 1 inch A: Drainage Area (Impervious Area Only) 4.00 ac. Rv: 0.05 + 0.009 (I) = 0.482 I: % of Impervious Area 48.0% * Total Storm Water Volume Control 1-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =16,868 cf (SCS Method) P: Design Storm, 1-yr 24-hr Storm Rainfall depth 2.8 inch A: Drainage Area 4.00 ac. S = 1,000/CN-10 =2.35 inch CN: Curve Number 81 * Estimated Storm Water Volume 10-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =24,339 cf (SCS Method) P: Design Storm, 10-yr 24-hr Storm Rainfall depth 3.46 inch A: Drainage Area 4.00 ac. S = 1000/CN-10 =2.35 inch CN: Curve Number 81 * Sedimentation Chamber Volume Min. Required: Vol-Pre = (0.2)(WQv) =1,400 cf * Sedimentation Chamber Volume Provided:3,200 cf * Filtration Media Surface Area Required: Af=[(WQv) (Df)]/ [(k) (Hf + Df) (Tf)] =684 sf (From Mecklenburg BMP Manual, Based on Darcy's Law) WQv: Water quality volume 6,999 cf Df: Filter bed depth (2'.5 for Optimal Efficiency)2.5 ft k: Permeability coefficient of filter media 3.50 ft/day (1.75" per hour, or 3.5' per day) Hf: Average height of water above filter bed, (half of pond depth, 1' max)0.94 ft Tf = Design filter bed drain time in days, (2 days beyond center 6-hr storm)2.125 days Depth of Pond Water (24" Max.)=24 inch * Filtration Media Surface Area Provided:700 sf BMP Storage Volume Provided: Elevation Surface Area Incremental Storage Total Storage (ft) (sf) (cf) (cf) 720.5 Bottom of Stone 721.5 Top of Stone/Bottom of Sand 724.0 Top of Sand Filter/ Bottom of Extended Dry Detention Pond 724.0 3,600 00Bottom of Pond 726.0 5,600 9,200 9,200 728.0 7,800 13,400 22,600 730.0 10,300 18,100 40,700 Top of Embankment Static Water Quality Elevation @ 725.52 ft Static Channel Protection Elevation @ 727.14 ft 48.0% (for Design) SHWTE and groundwater @ 708.71' per Summit Geo Report letter dated 11-14-17 FEMA 100 Year Flood Elevation @ 723.37' (DPR Flood Study dated 6-1-2018) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 1 of 3 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 2 of 3 DPR ASSOCIATES, INC SAND FILTER-4 DESIGN Prepared By: RJ Checked By: HN Date: 11-17-17 Revised 12-21-17 * BMP - SAND FILTER 4 * Water Draw Down Flow Rate Thru Sand Filter Media Qo = WQv / Tf = (Af)(k)(Hf+Df)/Df = 0.0499 cfs (Darcy's Law) k: Permeability coefficient of filter media 3.50 ft/day Af: Surface area, sf 684 sf Hf: Average height of water above filter bed 2.00 ft Df: Depth of soil filter bed 2.5 ft Q O @ Top of Media 724.0 = 0.0000 cfs Q O @ Median of WQv storage 724.8 =0.0506 cfs Q O @ Top of WQv storage 725.5 =0.0620 cfs * Time Drawdown from Inundation to Saturation surface Tf = WQv / Qo 38.99 hrs * Sizing Under Drain Pipes Q: Draw down rate thru sand filter 0.0499 cfs Use [2]-17 lf of 6" PVC or Sch 40, Use 2 of w/ 3/8" perforations spaced 3" on center, 4 rows w/ 90-deg apart 17 LF of 6 inch # of Perforation = (# pipes)(4 rows/ft) (Linear feet/per pipe -2') (4 holes/row) = (2 pipes)(4)(17 lf)(4)20 holes Capacity of one hole (3/8") = CA(2gh)^(0.5)(orifice equation)0.0078 cfs c= Discharge Coefficient 0.6 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) of 3/8" hole 0.0008 h= head above perforation 4.5 Total Capacity = Capacity of 1 hole x # of holes 0.1566 cfs Total Capacity w/ 50% lost to clogging 0.0783 cfs Underdrain Pipe Capacity= 1.49/n(A)(A/P)^(2/3) (S)^0.5 (Manning Eq)0.395 cfs n= pipe coefficient 0.013 A= Area (sf) of 6" dia pipe 0.1963 P= Pipe Perimeter, ft 1.57 s= slope, 0.5% 0.005 Underdrain Pipe Capacity w/ 50% lost to clogging 0.1974 cfs Both Flow Rates thru Perforation and Pipe are greater than that of Flow rate of Sand Filter. OK * Orifice Calcs For Channel Protection Dewatering Time 2 days (48 hrs) Beyond Center of 24-hr Storm (Sized for the Volume of 1-yr Storm with 50% remained at 36th Hour, 5% remained at 60th Hour, and drained completely at 120th Hour). 1-yr Storm Volume, Less 50% Remain Beyond 36th Hour 8,434 cf Average Surface Area 5,549 sf Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) a = 0.021 where: A= Resevoir Area, sf 5,549 Max. Orifice Diameter (inch), d = 1.98 h= Falling Head, ft 1.42 c= Discharge Coefficient 0.6 Orifice Diameter (inch) Used, d =2.5 t= Time ( 36 hrs), sec.129,600 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) * 1-yr Storm CPv Draw Down Flow Rate Thru Sand Media Qo = WQv / Tf 0.0781 cfs (Darcy's Law) CPv: 1-yr Storm Volume 16,868 cf Tf: 2 days beyond center of 24hr-storm, 60 hours 216,000 sec T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 2 of 3 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 3 of 3 DPR ASSOCIATES, INC SAND FILTER-4 DESIGN Prepared By: RJ Checked By: HN Date: 11-17-17 Revised 12-21-17 * BMP - SAND FILTER 4 Anti-Seep Collar Sizing Outlet Pipe Size (I.D.) = 24 in Outlet Pipe Size (O.D.) = 2.50 ft L, Length of Outlet Pipe = 40 lf Min. Flow Length = 46.0 ft Min. Flow Length = 115% of outlet pipe Total Lengh of Collar offset = 6.0 ft Number of anti-seep collars 2 Offset per collar 3.0 ft Min. Outside dimension of each collar 5.50 ft Designed collars 2 at 5.5' x 5.5' T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Sandfilter.xls printed 8/13/2018 page 3 of 3 Pond Report 23 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v12 Monday, 08 / 13 / 2018 Pond No. 4 - PH1 BMP 4 - SANDFILTER Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 724.00 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 724.00 3,600 0 0 2.00 726.00 5,600 9,200 9,200 4.00 728.00 7,800 13,400 22,600 6.00 730.00 10,300 18,100 40,700 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)= 24.00 3.00 6.00 0.00 Span (in)= 24.00 3.00 160.00 0.00 No. Barrels = 1 110 Invert El. (ft)= 720.40 725.60 727.20 0.00 Length (ft)= 40.00 0.50 0.50 0.00 Slope (%)= 1.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a Yes Yes No Crest Len (ft)= 0.00 0.00 0.00 0.00 Crest El. (ft)= 0.00 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = --- --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 4.00 8.00 12.00 16.00 20.00 24.00 28.00 32.00 36.00 40.00 44.00 Stage (ft) 0.00 724.00 1.00 725.00 2.00 726.00 3.00 727.00 4.00 728.00 5.00 729.00 6.00 730.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 1 of 2 DPR ASSOCIATES, INC SAND FILTER-1 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 12-21-17 DESIGN CRITERIA PER NCDENR STORMWATER DESIGN MANUAL DATED JAN 2017 * BMP - DRY POND 6 * Total Drainage Area:6.00 ac * Total Storm Water Volume Control 1-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =12,315 cf (SCS Method) P: Design Storm, 1-yr 24-hr Storm Rainfall depth 2.80 inch A: Drainage Area 6.00 ac. S = 1,000/CN-10 =4.49 inch CN: Curve Number 69 * Estimated Storm Water Volume 10-yr, 24-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =20,257 cf (SCS Method) P: Design Storm, 10-yr 24-hr Storm Rainfall depth 3.46 inch A: Drainage Area 6.00 ac. S = 1000/CN-10 =4.49 inch CN: Curve Number 69 BMP Storage Volume Provided: Elevation Surface Area Storage Total Storage (ft) (sf) (cf) (cf) 753.0 50 00Bottom of Pond 754.0 5,000 2,525 2,525 756.0 7,000 12,000 14,525 758.0 23,100 30,100 44,625 760.0 58,300 81,400 126,025 Top of Embankment Static Channel Protection Elevation @ 755.64 ft * Orifice Calcs For Channel Protection Dewatering Time 2 days (48 hrs) Beyond Center of 24-hr Storm (Sized for the Volume of 1-yr Storm with 50% remained at 36th Hour, 5% remained at 60th Hour, and drained completely at 120th Hour). 1-yr Storm Volume, Less 50% Remain Beyond 36th Hour 6,158 cf Average Surface Area 2,332 sf Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) a = 0.012 where: A= Resevoir Area, sf 2,332 Max. Orifice Diameter (inch), d = 1.49 h= Falling Head, ft 2.58 c= Discharge Coefficient 0.6 Orifice Diameter (inch) Used, d =1.5 t= Time ( 36 hrs), sec.129,600 g= Accelleration, ft/sq.sec 32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Dry Detention.xls printed 8/13/2018 page 1 of 2 Project: Village at Granite Job No.: 17031 Location: Granite Quarry, NC Sheet: 2 of 2 DPR ASSOCIATES, INC SAND FILTER-1 DESIGN Prepared By: RJ Checked By: HN Date: 10-17-17 Revised: 12-21-17 * BMP - SAND FILTER 6 Anti-Seep Collar Sizing Outlet Pipe Size (I.D.) = 15 in Outlet Pipe Size (O.D.) = 1.63 ft L, Length of Outlet Pipe = 53 lf Min. Flow Length = 61.0 ft Min. Flow Length = 115% of outlet pipe Total Lengh of Collar offset = 8.0 ft Number of anti-seep collars 2 Offset per collar 4.0 ft Min. Outside dimension of each collar 5.60 ft Designed collars 2 at 5.5' x 5.5' T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Dry Detention.xls printed 8/13/2018 page 2 of 2 Pond Report 25 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v12 Monday, 08 / 13 / 2018 Pond No. 5 - PH1 BMP 6 - DRY DETENTION Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 753.00 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 753.00 50 0 0 1.00 754.00 500 275 275 3.00 756.00 2,400 2,900 3,175 5.00 758.00 23,100 25,500 28,675 7.00 760.00 58,300 81,400 110,075 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)= 15.00 1.50 6.00 0.00 Span (in)= 15.00 1.50 138.00 0.00 No. Barrels = 1 110 Invert El. (ft)= 753.00 753.00 756.50 0.00 Length (ft)= 53.00 0.50 0.50 0.00 Slope (%)= 0.56 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a Yes Yes No Crest Len (ft)= 0.00 0.00 0.00 0.00 Crest El. (ft)= 0.00 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = --- --- --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 Stage (ft) 0.00 753.00 2.00 755.00 4.00 757.00 6.00 759.00 8.00 761.00 Elev (ft) Discharge (cfs) Stage / Discharge Total Q DPR ASSOCIATES, INC BMP OUTLET STRUCTURE BOUYANCY CALCULATION OUTLET STRUCTURE BOUYANCY CALCULATION NCDOT #840.04 BMP Number BMP #1 BMP #2 BMP #3 BMP #4 BMP #6 Structure Number 1-400 2-200 3-400 4-200 5-106 WEIGHT OF DISPLACED WATER BY STRUCTURE Volume of riser: Outlet Pipe Diameter (in) =18 36 36 24 15 Length (ft) =5.00 5.50 5.50 5.00 3.50 Width (ft) =3.67 5.00 5.00 3.67 2.25 Wall thickness (ft) = 0.50 0.50 0.50 0.50 0.50 Weir Elev (ft) =736.00 736.00 731.80 726.50 727.20 Invert Out (in) =728.36 728.35 724.33 719.45 720.40 Height of Riser to Weir (ft) = 7.64 7.65 7.47 7.05 6.80 Riser Volume (cu.ft) =140.07 210.37 205.42 129.25 53.55 Volume of base: Length (ft) = 6.00 6.50 6.50 6.00 4.50 Width (ft) = 4.67 6.00 6.00 4.67 3.25 Hight (ft) = 0.67 0.67 0.67 0.67 0.67 Base Volume (cu.ft) = 18.76 26.00 26.00 18.67 9.75 Area Loss for outlet pipe opening (sf): 2.25 4.00 4.00 2.83 1.96 Volume Loss for outlet pipe opening (cu.ft): -3.98 -12.57 -12.57 -6.31 -3.01 Total Volume of Structure: 154.85 223.81 218.86 141.61 60.29 Weight of Water (lbs/cu.ft) = 62.4 62.4 62.4 62.4 62.4 Weight of Water Displaced (lbs)9,663 13,966 13,657 8,837 3,762 WEIGHT OF STRUCTURE Volume of Base (cu ft) = 18.76 26.00 26.00 18.67 9.75 Volume of riser: Outside area (sf) = 18.33 27.50 27.50 18.33 7.88 Inside area (sf) = 10.67 18.00 18.00 10.67 3.13 Net area (sf) = 7.67 9.50 9.50 7.67 4.75 Height of Riser to Weir (ft) = 7.64 7.65 7.47 7.05 6.80 Volume of Riser (cu ft) = 58.57 72.67 70.96 54.05 32.30 Area Loss for outlet pipe opening (sf): 2.25 4.00 4.00 2.83 1.96 Volume Loss for outlet pipe opening (cu.ft): -3.98 -12.57 -12.57 -6.31 -3.01 Net Volume of Riser (sf) = 54.60 60.11 58.40 47.74 29.29 Volume of Posts (cu.ft): Weir Height (in) = 6.00 7.00 8.00 9.00 10.00 Volume of Posts (cu.ft) = 0.90 1.04 1.19 1.33 1.48 Volume of Top Slab (cu.ft): Length (ft) = 6.00 6.50 6.50 6.00 4.50 Width (ft) = 4.67 6.00 6.00 4.67 3.25 Thickness (in) = 4.00 5.00 6.00 7.00 8.00 Volume of Top slab (cu.ft) = 9.33 16.25 19.50 16.33 9.75 Volume Loss for Opening for Frame/Cover (cu ft) = 1.22 1.53 1.83 2.14 2.44 Volume of Top slab (cu.ft) = 8.11 14.72 17.67 14.20 7.31 Weight of Concrete in Structure (lbs) = 12,355 15,280 15,488 12,291 7,174 Weight of Ring and Cover (lbs) = 230 231 232 233 234 Total Weight Structure (lbs) =12,585 15,511 15,720 12,524 7,408 Anchor Block: Length (ft) = 6.00 6.50 6.50 6.00 4.50 Width (ft) = 4.67 6.00 6.00 4.67 3.25 Height (ft) =0.00 0.00 0.00 0.00 0.00 Anchor Block Volume (cu.ft) = 0.0 0.0 0.0 0.0 0.0 Weight of Water (lbs/cu.ft) = 62.4 62.4 62.4 62.4 62.4 Weight of Water Displaced by Anchor Block (lbs)0000 0 Weight of Anchor Block (lbs)0000 0 Not Required Not Required Not Required Not Required Not Required NET BOUYANCY*** Weight of Water Displaced (lbs) 9,663 13,966 13,657 8,837 3,762 Total Weight Structure (lbs) = 12,585 15,511 15,720 12,524 7,408 Bouyancy (lbs) = 2,922 1,546 2,063 3,688 3,646 Safety Factor = 1.30 1.11 1.15 1.42 1.97 *** Includes anchor block, if needed T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1 BMP Anchor Block.xls printed 8/13/2018