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Home My WebLink AboutDrainage Report DRAINAGE REPORT FOR NEW CONVENIENCE STORE / FOOD MART 2425 HARLESTON STREET CARMEL, INDIANA November, 2021 PREPARED BY: Total Engineering Solutions Co., LLC 9955 Crosspoint Blvd., Suite 100 Indianapolis, IN 46256 TECHNICAL DRAINAGE REPORT TABLE OF CONTENTS ITEM PAGE Project Narrative & Calculations 1-5 Hydrograph Summary Report and Hydrographs 6-21 Soils Map 22-24 Flood Plain (FIRM) Map 25 DRAINAGE REPORT FOR CONVENIENCE STORE / FOOD MART 2425 HARLESTON DRIVE CARMEL, IN PROJECT NARRATIVE: This project consists of the construction of a 4223 sft. convenience store, a dumpster enclosure, gas pumps, concrete sidewalk and asphalt pavement on a 1.1-acre parcel. Street parking will be constructed north of the site along Harleston Drive, and two entrances are planned, one from Harleston Drive and another, one-way (south) entrance/exit from Towne Road. The site is part of the Village of West Clay PUD and is included in the Master Drainage Report and stormwater detention system. The project will disturb approximately 0.81 acres of the 1.1- acre parcel. The project will disturb approximately 0.81 acres of the 1.1-acre parcel. EXISTING CONDITIONS: The existing property is a grass field at the southwest corner of Harleston Drive & Towne Road, which sheet drains primarily to the east, into an existing storm sewer system along Towne Road. The public storm sewer system discharges to a regional detention basin north of the site which is located north of the site. Per the original Village of West Clay master drainage report, the storm sewer system and regional stormwater detention pond was designed based on an NRCS curve number of 88 on the project site. Site Soils Site soils within the property and project area are classified as Brookston silty clay loam-Urban land complex (YbvA), which is a Group B soil, and Crosby silt loam, fine-loamy subsoil-Urban land complex (YclA), which is a Group C soil. Predicted Storm Runoff As predicted from the attached Hydrographs (Rational Method), the pre-developed storm water runoff rates are as follows: Storm Event Basin 1 Q2 1.28 cfs Q10 2.65 cfs Q25 3.82 cfs Q100 6.25 cfs 1 11/17/21 PROPOSED CONDITIONS: The proposed site improvements will consist of a new 4223 sft. Convenience Store/Food Mart, new parking area, concrete sidewalks, and a dumpster enclosure. As shown in the hydrographs below, this increase in impervious area will also result in an increase in peak stormwater runoff (0.53 cfs at a 100 year storm event). Stormwater runoff will sheet drain into a new storm sewer system, which will convey stormwater into a mechanical pollutant-filtering unit, followed by a second unit to remove any remaining suspended solids. Using the rational method, the stormwater runoff from the post-developed site, as predicted by the Hydrographs attached, is as follows: Storm Event Basin 1 Post-Developed Q2 2.05 cfs (vs. 1.28 cfs pre-developed) Q10 3.67 cfs (vs. 2.65 cfs pre-developed) Q25 4.95 cfs (vs 3.82 cfs pre-developed) Q100 7.46 cfs (vs 6.25 cfs pre-developed) In order to determine whether or not additional on-site stormwater detention is needed to supplement the regional basin, the NRCS curve number for the developed site needs to be calculated and compared to the Cn of 88 predicted. As shown in the calculations below, the developed site as proposed will result in a weighted curve number (Cn) of 84.1 which is less than the 88 assumed. Therefore, no additional on-site detention is required or proposed for the project. Storm Water Quality The project will disturb a total of 0.81 acres and under current ordinances and standards of the City of Carmel, must include stormwater quality measures for treating runoff. After evaluating several alternatives to meeting the storm water treatment requirements, we have proposed the use of a flow through type hydro-dynamic separator type unit, specifically an Aqua- Swirl model AS-2 installed in conjunction with an Aqua-Filter Model AF-X.2 unit which will provide additional treatment and filtering including for potential hydrocarbons which may be found in the stormwater runoff due to the gas station pumps and potential for minor spills. The two units will be installed to collectively make up a stormwater treatment train that meets the City of Carmel’s stormwater ordinance requirements. As shown in flow through BMP calculations below and the BMP Hydrograph included in this report, the, first flush rain event rate required to be treated by the BMP is 0.932 cfs. The selected treatment units were sized by the manufacturer to adequately treat this peak flow rat 2 11/17/21 SUMMARY AND CONCLUSIONS: The proposed project will disturb approximately 0.81 acres of the 1.10 acre site and the new development will significantly increase the hard surface (impervious) area of the current property. The developed site will result in a stormwater runoff curve of 84.1 which is below the 88 number predicted by the original Village of West Clay master drainage report. Therefore, the existing storm sewer system and off-site regional detention pond located north of the site is adequately sized to receive and store the peak stormwater runoff from the site. The project will include a stormwater quality measure (BMP) train including both a hydro- dynamic separator and filtration units treat the Stormwater Quality Volume from the site. With the addition of stormwater treatment, the proposed improvements will have no adverse impacts to the downstream stormwater infrastructure. 3 11/17/21 DRAINAGE CALCULATIONS Existing (Pre-Developed) Conditions The pre-developed project includes the 1.1-acre parcel. A summary of the current land use designations is as follows: Description Total Area Grass Grass Gravel Basin #1 1.10 Acres 0.435 Acres 0.465 Acres 0.20 Acres (Type B Soil) (Type C Soil) Existing Basin #1 Runoff (SCS Method) Q= CiA where C= Weighted Curve No.Cn Cn = (0.435 x 69)+(0.465 x 79) + (0.20 x 85)/1.10 = 76.1 Time of Concentration (Tc) = 5 minutes Storm Event Basin 1 Q2 1.28 cfs Q10 2.65 cfs Q25 3.82 cfs Q100 6.25 cfs Post Developed Conditions The pre-developed project includes the 1.1-acre parcel. A summary of the current land use designations is as follows: Description Total Area Grass Grass Pavement Roof Basin #1 1.10 Acres 0.290 Acres 0.186 Acres 0.52 Acres 0.096 Acres (Type B Soil) (Type C Soil) Post-Developed Basin #1 Runoff (SCS Method) Q= CiA where C= Weighted Curve No.Cn Cn = (0.290 x 61)+(0.190 x 74) + (0.520 x 98) + (0.100 x 98)/1.10 = 84.1 Time of Concentration (Tc) = 5 minutes Storm Event Basin 1 Q2 2.05 cfs Q10 3.67 cfs Q25 4.95 cfs Q100 7.46 cfs 4 11/17/21 FLOW THROUGH BMP SIZING: Contributing Drainage Area = 1.10 Acres Percent Impervious Area: 0.616/1.10 = 0.560 (56.0%) Water Quality Curve Number: CNwq = 95 (From Exhibit 701-1) Based on a 1” Rain Event, 24 Hour storm, and Type II distribution, the Peak Storm Water Quality Volume as provided by the BMP Hydrograph = 0.932 cfs. 5 11/17/21 611/17/21 711/17/21 811/17/21 911/17/21 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 1.281 3 720 2,970 ------ ------------ Basin 1 Pre-Developed (Target Q) 2 SCS Runoff 2.054 3 717 4,647 ------------------ Basin 1 Post Developed 21043 Storm Hydrograph.gpw Return Period: 2 Year Wednesday, 11 / 17 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 10 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 1 Basin 1 Pre-Developed (Target Q) Hydrograph type = SCS Runoff Peak discharge = 1.281 cfs Storm frequency = 2 yrs Time to peak = 12.00 hrs Time interval = 3 min Hyd. volume = 2,970 cuft Drainage area = 1.100 ac Curve number = 76* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 2.66 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.440 x 69) + (0.470 x 79) + (0.200 x 85)] / 1.100 0 3 6 9 12 15 18 21 24 27 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (hrs) Basin 1 Pre-Developed (Target Q) Hyd. No. 1 -- 2 Year Hyd No. 1 11 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 2 Basin 1 Post Developed Hydrograph type = SCS Runoff Peak discharge = 2.054 cfs Storm frequency = 2 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 4,647 cuft Drainage area = 1.100 ac Curve number = 84* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 2.66 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.520 x 98) + (0.100 x 98) + (0.290 x 61) + (0.190 x 74)] / 1.100 0 3 6 9 12 15 18 21 24 27 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (hrs) Basin 1 Post Developed Hyd. No. 2 -- 2 Year Hyd No. 2 12 11/17/21 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 2.646 3 717 6,025 ------ ------------ Basin 1 Pre-Developed (Target Q) 2 SCS Runoff 3.673 3 717 8,318 ------------------ Basin 1 Post Developed 21043 Storm Hydrograph.gpw Return Period: 10 Year Wednesday, 11 / 17 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 13 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 1 Basin 1 Pre-Developed (Target Q) Hydrograph type = SCS Runoff Peak discharge = 2.646 cfs Storm frequency = 10 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 6,025 cuft Drainage area = 1.100 ac Curve number = 76* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.83 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.440 x 69) + (0.470 x 79) + (0.200 x 85)] / 1.100 0 3 6 9 12 15 18 21 24 27 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (hrs) Basin 1 Pre-Developed (Target Q) Hyd. No. 1 -- 10 Year Hyd No. 1 14 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 2 Basin 1 Post Developed Hydrograph type = SCS Runoff Peak discharge = 3.673 cfs Storm frequency = 10 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 8,318 cuft Drainage area = 1.100 ac Curve number = 84* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 3.83 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.520 x 98) + (0.100 x 98) + (0.290 x 61) + (0.190 x 74)] / 1.100 0 3 6 9 12 15 18 21 24 27 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (hrs) Basin 1 Post Developed Hyd. No. 2 -- 10 Year Hyd No. 2 15 11/17/21 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 3.822 3 717 8,635 ------ ------------ Basin 1 Pre-Developed (Target Q) 2 SCS Runoff 4.946 3 717 11,288 ------------------ Basin 1 Post Developed 21043 Storm Hydrograph.gpw Return Period: 25 Year Wednesday, 11 / 17 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 16 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 1 Basin 1 Pre-Developed (Target Q) Hydrograph type = SCS Runoff Peak discharge = 3.822 cfs Storm frequency = 25 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 8,635 cuft Drainage area = 1.100 ac Curve number = 76* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 4.72 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.440 x 69) + (0.470 x 79) + (0.200 x 85)] / 1.100 0 3 6 9 12 15 18 21 24 27 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (hrs) Basin 1 Pre-Developed (Target Q) Hyd. No. 1 -- 25 Year Hyd No. 1 17 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 2 Basin 1 Post Developed Hydrograph type = SCS Runoff Peak discharge = 4.946 cfs Storm frequency = 25 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 11,288 cuft Drainage area = 1.100 ac Curve number = 84* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 4.72 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.520 x 98) + (0.100 x 98) + (0.290 x 61) + (0.190 x 74)] / 1.100 0 3 6 9 12 15 18 21 24 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 Q (cfs) Time (hrs) Basin 1 Post Developed Hyd. No. 2 -- 25 Year Hyd No. 2 18 11/17/21 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft)(ft)(cuft) 1 SCS Runoff 6.245 3 717 14,151 ------ ------------ Basin 1 Pre-Developed (Target Q) 2 SCS Runoff 7.462 3 717 17,327 ------------------ Basin 1 Post Developed 21043 Storm Hydrograph.gpw Return Period: 100 Year Wednesday, 11 / 17 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 19 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 1 Basin 1 Pre-Developed (Target Q) Hydrograph type = SCS Runoff Peak discharge = 6.245 cfs Storm frequency = 100 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 14,151 cuft Drainage area = 1.100 ac Curve number = 76* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 6.46 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.440 x 69) + (0.470 x 79) + (0.200 x 85)] / 1.100 0 3 6 9 12 15 18 21 24 27 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 7.00 7.00 Q (cfs) Time (hrs) Basin 1 Pre-Developed (Target Q) Hyd. No. 1 -- 100 Year Hyd No. 1 20 11/17/21 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 11 / 17 / 2021 Hyd. No. 2 Basin 1 Post Developed Hydrograph type = SCS Runoff Peak discharge = 7.462 cfs Storm frequency = 100 yrs Time to peak = 11.95 hrs Time interval = 3 min Hyd. volume = 17,327 cuft Drainage area = 1.100 ac Curve number = 84* Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 6.46 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 * Composite (Area/CN) = [(0.520 x 98) + (0.100 x 98) + (0.290 x 61) + (0.190 x 74)] / 1.100 0 3 6 9 12 15 18 21 24 Q (cfs) 0.00 0.00 2.00 2.00 4.00 4.00 6.00 6.00 8.00 8.00 Q (cfs) Time (hrs) Basin 1 Post Developed Hyd. No. 2 -- 100 Year Hyd No. 2 21 11/17/21 Soil Map—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/14/2021 Page 1 of 344253104425320442533044253404425350442536044253704425380442539044254004425310442532044253304425340442535044253604425370442538044253904425400567930567940567950567960567970567980567990568000568010568020568030568040568050568060568070568080 567930 567940 567950 567960 567970 567980 567990 568000 568010 568020 568030 568040 568050 568060 568070 568080 39° 58' 33'' N 86° 12' 16'' W39° 58' 33'' N86° 12' 9'' W39° 58' 30'' N 86° 12' 16'' W39° 58' 30'' N 86° 12' 9'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 16N WGS84 0 35 70 140 210 Feet 0 10 20 40 60 Meters Map Scale: 1:727 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale.2211/17/21 MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features 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 1:15,800. 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: Hamilton County, Indiana Survey Area Data: Version 22, Sep 9, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 1, 2018—Sep 30, 2018 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. Soil Map—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/14/2021 Page 2 of 32311/17/21 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI YbvA Brookston silty clay loam- Urban land complex, 0 to 2 percent slopes 1.2 50.9% YclA Crosby silt loam, fine-loamy subsoil-Urban land complex, 0 to 2 percent slopes 1.1 49.1% Totals for Area of Interest 2.3 100.0% Soil Map—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/14/2021 Page 3 of 3 24 11/17/21 National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 10/12/2021 at 1:38 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 86°12'31"W 39°58'48"N 86°11'54"W 39°58'21"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 20202511/17/21