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HomeMy WebLinkAboutTechnical Information Report rev 6.11.25 STORMWATER DRAINAGE TECHNICAL REPORT FOR Citizens Energy Group White River North Water Treatment Plant Expansion 11825 River Rd Carmel, IN 46033 Prepared by: JPS Consulting Engineers 9365 Counselors Row Suite 116 Indianapolis, IN 46240 23 April 2025 Certified by: TABLE OF CONTENTS I. Foreword II. Site Location III. Site History IV. Zoning Commitments V. Existing Conditions VI. Storm Sewer Design VII. Stormwater Quality VIII. Stormwater Runoff IX. Stormwater Detention X. Summary Appendix A Vicinity & Location Maps Appendix B Floodplain & Soil Maps Appendix C Storm Sewer Calculations Appendix D Stormwater Quality Calculations Appendix E Stormwater Detention Calculations STORMWATER DRAINAGE TECHNICAL REPORT I. Foreword The proposed project consists of the expansion of the existing White River North Water Treatment Plant. The expansion will construct an underground chlorine contact basin, two open top sedimentation basins, a partially open top residual management structure, and two enclosed buildings, the filter building and dewatering building. A new driveway off River Rd will also be constructed and some interior drive areas to allow for truck deliveries to the new buildings. The project is located on the east side of River Rd, just north of the River Heritage city Park. Non City of Carmel permits required are the IDEM Construction Stormwater General Permit (CSGP) as well as the Construction in a Floodway permit from IDNR. The permit application paperwork for the Floodway permit is being submitted under separate cover. Construction will take place adjacent to the existing water treatment plant and throughout the property. Water treatment processes will continue throughout construction. The site is generally sloped to the north and east. There is a private storm sewer that runs along the north end of the property that drains directly into the White River which is on the east side of the property. Due to the closed nature of the existing drainage system and the direct discharge into the river, no detention is proposed. A formal waiver request has been included with Appendix G. No formal water quality measures are proposed and a waiver from the water quality requirements is requested and included in Appendix F. However, an existing residual basin that will be made obsolete by the improvements is going to be maintained and will serve as an informal infiltration water quality basin. This basin will not capture the entire project area, however the largest area of hard scape will drain into the basin and then will infiltrate through the soil. This basin is currently used as part of the water treatment process and has sandy soils to allow for water infiltration. HydroCAD was used for all hydrologic modeling for the overall site project run-off. Hydraflow Storm Sewers computer program was used to verify the capacity of the proposed storm sewers. All input and calculation reports are included in the various appendixes and discussed in more detail in the following sections. Another summary of the drainage is also included on sheet C04-01 of the construction drawings and copied here for reference: This report contains information on the stormwater management for the project including proposed stormwater conveyance/pipe design, stormwater quantity, and stormwater quality for the project. The proposed stormwater management is intended to meet the City of Carmel Stormwater Technical Standards Manual and request waivers from two items. II. Site Location The project is located 11825 River Rd, north of 116th St. The project will construct various buildings and structrures that are part of the water treatment process. Most of the structures are either underground or open top basins which will not contribute to run-off as rainwater is contained within them. The project site is bordered by River Rd to the west, White River to the east, and residential properties to the north and a hotel to the south. Land use for the bordering parcels is summarized below: A site location and vicinity maps and a zoning map are included in Appendix A for reference. III. Existing Conditions The existing property is the current White River North Water Treatment Plant operated by Citizens Energy Group. Existing drainage on the site is largely surface run-off with a few storm inlets throughout the site. The site drains directly into the White River. The existing storm system on the property collects water from the site only and then discharges that into the White River. The White River abuts the property along the west side. Per the FEMA FIRM Map there is a floodway and floodplain present at the site from the White Riever. The existing soils on site are several silt loam complexes and clay loam complexes. Soil and the FEMA FIRM flood map for the site are included in Appendix B. IV. Storm Sewer Design The storm sewer system being added for the project is fairly minimal and mainly just to keep water from free draining across the new driveway. Those new storm pipes have been modeled for gravity flow with the Hydraflow Storm Sewers software using the Rational Method and a 10-year frequency design storm. The new storm system drains majority green space from the north side of the hill of the new underground chlorine contact basin and the area around the new filter building and sedimentation basins. These storm structures drain into the existing storm system on the property which discharges into the White River. Runoff coefficients were determined by land use and adjusted to the next least pervious soil classification per Camel Stormwater Technical Standards Manual. Direction Land Use Carmel Zoning North Residential S-1 South Park S-1 West Residential S-1 East White River N/A Design storm values are per the Carmel Stormwater Technical Standards Manual. The storm sewer calculations are included in Appendix C. In addition, inlets have been sized to calculate the gutter spread to ensure that each existing inlet can accommodate the drainage watershed without being inundated. Per the Carmel Stormwater Technical Standards, each inlet was analyzed at 50% clogged. All of the inlets were able to handle the flows from their respective watersheds without flooding the roadway. Inlet capacity calculations are included in Appendix D. DOWNSTREAM RECEIVING STORM SYSTEM There is no downstream receiving storm system as the on-site storm system only drains the CEG property and discharges directly into the White River. V. Site Run-Off As a result of this project, run-off leaving the site will be increased. However, the area of land that is contributing to generating run-off is being reduced in the post developed condition due to the construction of various open area, water basins which will collect any rainwater within the basin and incorporate it as part of the process. Per the soils map, the existing soil hydrologic group values are as follows: Per the Carmel Stormwater Technical Standards Manual, the soil groups are to be changed to the next less infiltrating group for the purpose of determining the post construction run-off. Since the existing soils were in the B, hydrologic group, the soil properties for the C hydrologic group were used. The characteristics of the proposed soil is summarized in the following table: The pre and post construction run-off leaving the site and flowing into the drainage pond is summarized below: Note the total areas do not match as some of the proposed buildings are open top basins which will collect and hold any rainwater that falls into them These values represent the run-off generated by the existing conditions and as a result of this project. Soil Symbol Soil Name Soil Hydrologic Group Impervious Cn Value Pervious Cn Value OcA, OcB2, YoxA Ockley silt loam B 98 61 UcfA & YclA Urban Land- Crosby Silt loam B 98 61 Soil Hydrologic Group Impervious Cn Value Pervious Cn Value Group C 98 74 Pervious Area Impervious Area Cn Value 2 Year Run-off 10 Year Run-off 100 Year Run-off Pre- Developed 7.00ac 0.68ac 68 7.69 cfs 11.55 cfs 16.30 cfs Post- Developed 5.22ac 1.18ac 78 9.23 cfs 13.65 cfs 19.03 cfs They also ignore in the post developed condition, any surface area that may drain into self contained natural basins. The Cn values were calculated using the following formula: 𝐶𝑁= (𝐶𝑁𝑖𝑚𝑜𝑒𝑟𝑢𝑖𝑜𝑢𝑟× 𝑖𝑙𝑜𝑒𝑟𝑟𝑖𝑜𝑟𝑟𝑎𝑟𝑒𝑎)× (𝐶𝑁𝑜𝑒𝑟𝑢𝑖𝑜𝑢𝑟× 𝑜𝑒𝑟𝑟𝑖𝑜𝑟𝑟𝑎𝑟𝑒𝑎) 𝑇𝑜𝑟𝑎𝑙 𝐴𝑟𝑒𝑎 For the pre developed condition the values was calculated as follows: 𝐶𝑁= (61 × 7.00)+(98 × 0.68) 7.68 =68 For the post- developed condition the values were calculated as follows: 𝐶𝑁= (74 × 5.22)+(98 × 1.18) 6.40 =78 Run-off calculations are provided in Appendix E. VI. Stormwater Detention A waiver from the stormwater detention/water quantity requirement is being requested. The formal waiver and documentation and explanation is provided in Appendix G. VII. Stormwater Quality A waiver from the post construction stormwater quality treatment is also being requested for the project. The formal waiver and documentation and explanation is provided in Appendix F. There is an area of the site that will drain into an existing self contained infiltration basin. This basin is currently used for the drying of residuals from the water treatment process. With the project, this basin will be reduced in size to allow for the construction of two new buildings and will ultimately not be used for residuals any longer. The remaining basin is proposed to be left in place as an informal infiltration basin which will help with stormwater quality. The basin will be planted with grass and other natural plants and will be kept free from pesticides and other herbicides. This area will be maintained as an informal stormwater quality measure which will treat a large portion of the newly added impervious surface being installed with this project. The calculations for the basin and a drainage map showing the area draining into the basin is included in Appendix E. VIII. Summary The CEG WRN WTP Expansion project will include the construction of multiple new structures that will be built underground or with open top and generate no run-off. Two new buildings will also be constructred along with various drive aisles for access and a new driveway off River Rd. The project is seeking a waiver from the stormwater detention and stormwater quality requirements. A portion of the new site will drain into an informal infiltration basin that is currently used for residual drying but will not be used for that purpose once construction is finished. This basin will contain and allow for infiltration of the collected stormwater. The minimal new storm sewers have been checked to verify they will convey the 10-year design storm run-off rates. The storm system discharges directly into the White River and only drains the subject property. APPENDIX A: LOCATION & VICINITY MAPS PROJECT SITE LOCATION MAP VICINITY MAP ZONING: S-1 LAND USE: RESIDENTIAL ZONING: S-1 LAND USE: RESIDENTIAL ZONING: S-1 LAND USE: RESIDENTIAL CITY OF FISHERS LAND USE: GOLF COURSE RIVER ROAD ZONING: P-1 LAND USE: GOLF COURSE ZONING: S-1 LAND USE: PARK APPENDIX B: SOIL AND FLOODPLAIN MAPS SOILS MAP FL O O D M A P APPENDIX C: STORM SEWER CALCULATIONS 2 7 " S A S S A F R A S 2 4 " T W I N P I N E 1 2 " D E A D 1 0 " P I N E 1 5 " P I N E 4 " S A S S . 1 2 " P I N E S A F E T Y S W I T C H 12" CMP S T R . #5 T C : 7 3 9 .4 0 (N O P I P E S V I S I B L E ) 4 8 " R C P S T R . #6 T C : 7 4 5 .0 5 F R O M S W : 7 3 1 .1 5 T O N O R T H : 7 3 1 .0 0 6 " P V C S T R . #7 T C : 7 4 4 .9 2 F R O M N O R T H : 7 4 1 .0 1 F R O M S W : 7 3 0 .4 8 48" RCP 48" RCP 8 " P V C 8 " P V C S T R . #8 T C : 7 4 4 .9 2 T O E A S T : 7 4 0 .0 2 4 8" RCP S T R . #9 T C : 7 4 5 .4 5 F R O M S W : 7 3 1 .0 1 F R O M W E S T : 7 3 9 .9 3 T O N E : 7 2 9 .6 6 54" RCP 3 6 " R C P 3 6 " R C P S T R . #1 0 T C : 7 4 3 .4 2 F R O M S W : 7 2 9 .3 2 F R O M W E S T : 7 3 1 .3 7 T O N E : 7 2 9 .3 0 5 4 " R C P S T R . #1 1 T C : 7 4 3 .3 0 F R O M S W : 7 2 9 .0 9 T O E A S T : 7 2 9 .0 7 S T R . #1 2 T C : 7 4 3 .1 9 T O E A S T : 7 3 2 .8 0 (N O O T H E R P I P E S V I S I B L E ) 12" Steel E L E C T R I C U T I L I T Y T R A N S F O R M E R R O O F D R A I N I N V E L 7 4 4 .5 0 6" P V C R O O F D R AIN 224.00' (D) S 34°05'00"W 4 2 " S T O R M S E W E R S T O R M I N L E T R I M E L . 7 3 6 .7 0 I.E . 7 3 1 .1 8 3 /4 " G A S L I N E S t o r m I n l e t T C : 7 4 4 .0 0 I n v : 7 4 1 .0 0 S 7 4 °4 0 '0 0 " E 6 4 5 .9 2 ' (D ) 6 PAC SILO PAC SILO STR-1 STR-2 STR-3 STR-4 STR-5 STR-6 STR-7 STR-8 BASIN 8 TOTAL: 0.10ac IMP: 0.00ac PER: 0.10ac BASIN 3 TOTAL: 0.24ac IMP: 0.05ac PER: 0.19ac BASIN 2 TOTAL: 0.06ac IMP: 0.00ac PER: 0.06ac BASIN 4 TOTAL: 0.32ac IMP: 0.09ac PER: 0.23ac BASIN 5 TOTAL: 0.08ac IMP: 0.02ac PER: 0.06ac BASIN 6 TOTAL: 0.05ac IMP: 0.00ac PER: 0.05ac BASIN 7 TOTAL: 0.07ac IMP: 0.02ac PER: 0.05ac BASIN 1 TOTAL: 0.20ac IMP: 0.00ac PER: 0.20ac 0 60 120 FEET SCALE:1"=60' DESIGNED BY: PROJECT NO.: DATE:APRIL 2025 CONSULTANTS SEALS NO.ISSUED FORDATE BY DRAWN BY: CHECKED BY: COPYRIGHT: SHEET TITLE 1 2 3 4 5 6 A B C D E User:NVERGATOS Spec:AUS-NCSMOD File:K:\CIVIL PROJECTS\2024\24JPSC56 CEG WRN TREATMENT PLAN\DRAWINGS\BASINS.DWG Scale:1:1 SavedDate:4/23/2025 Time:09:25 Plot Date: Nick Vergatos; 4/23/2025; 11:39 ; Layout:STM 30239923 WHITE RIVER NORTH WTP EXPANSION ARCADIS U.S., INC., 2023 SHEET NO.: SCALE: ISSUE STATUS: PERMIT SET LEGAL ENTITY: ARCADIS U.S., INC. 0 1 BAR IS ONE INCH ON UNREDUCED DRAWING SHEET TITLE NBV CLM NBV AS NOTED POST DEVELOPED BASIN POST Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jan 26 2023 0.25% Slope Pipe @ Full Flow Circular Diameter (ft)= 1.00 Invert Elev (ft)= 100.00 Slope (%)= 0.25 N-Value = 0.013 Calculations Compute by:Known Depth Known Depth (ft)= 0.80 Highlighted Depth (ft)= 0.80 Q (cfs)= 1.741 Area (sqft)= 0.67 Velocity (ft/s)= 2.58 Wetted Perim (ft)= 2.22 Crit Depth, Yc (ft)= 0.56 Top Width (ft)= 0.80 EGL (ft)= 0.90 0 1 2 3 Elev (ft)Depth (ft)Section 99.50 -0.50 100.00 0.00 100.50 0.50 101.00 1.00 101.50 1.50 102.00 2.00 Reach (ft) APPENDIX D: INLET CAPACITY CALCULATIONS Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:2560-D Perimeter (ft):5.10 Open Area (sf):1.00 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((1.7+3)/2) x .80 = 1.7 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =1.7 cfs allowable Qi =Use Orifice Flow Equation 1.7 1.7 3.00 Allowable Inlet Flow = 1.7 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.20 I =6.12 in/hr T.C. =5.0 min A =0.20 ac 0.2 Actual Inlet Flow = 0.2 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-1 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:3286-8 Perimeter (ft):4.40 Open Area (sf):0.70 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((1.2+2.6)/2) x .80 = 1.2 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =1.2 cfs allowable Qi =Use Orifice Flow Equation 1.2 1.2 2.60 Allowable Inlet Flow = 1.2 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.20 I =6.12 in/hr T.C. =5.0 min A =0.06 ac 0.1 Actual Inlet Flow = 0.1 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-2 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:3405 Perimeter (ft):7.90 Open Area (sf):1.50 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((2.6+4.6)/2) x .80 = 2.6 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =2.6 cfs allowable Qi =Use Orifice Flow Equation 2.6 2.6 4.60 Allowable Inlet Flow = 2.6 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.35 I =6.12 in/hr T.C. =5.0 min A =0.24 ac 0.5 Actual Inlet Flow = 0.5 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-3 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:3405 Perimeter (ft):7.90 Open Area (sf):1.50 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((2.6+4.6)/2) x .80 = 2.6 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =2.6 cfs allowable Qi =Use Orifice Flow Equation 2.6 2.6 4.60 Allowable Inlet Flow = 2.6 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.40 I =6.12 in/hr T.C. =5.0 min A =0.32 ac 0.8 Actual Inlet Flow = 0.8 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-4 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:3405 Perimeter (ft):7.90 Open Area (sf):1.50 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((2.6+4.6)/2) x .80 = 2.6 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =2.6 cfs allowable Qi =Use Orifice Flow Equation 2.6 2.6 4.60 Allowable Inlet Flow = 2.6 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.38 I =6.12 in/hr T.C. =5.0 min A =0.08 ac 0.2 Actual Inlet Flow = 0.2 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-5 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:3405 Perimeter (ft):7.90 Open Area (sf):1.50 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((2.6+4.6)/2) x .80 = 2.6 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =2.6 cfs allowable Qi =Use Orifice Flow Equation 2.6 2.6 4.60 Allowable Inlet Flow = 2.6 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.20 I =6.12 in/hr T.C. =5.0 min A =0.05 ac 0.1 Actual Inlet Flow = 0.1 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-6 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:3405 Perimeter (ft):7.90 Open Area (sf):1.50 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((2.6+4.6)/2) x .80 = 2.6 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =2.6 cfs allowable Qi =Use Orifice Flow Equation 2.6 2.6 4.60 Allowable Inlet Flow = 2.6 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.40 I =6.12 in/hr T.C. =5.0 min A =0.07 ac 0.2 Actual Inlet Flow = 0.2 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-7 23-Apr-25 Project Name:Structure: Job Number:Date: Design Depth of Water Over Grate (ft.):0.50 % Plugged:50%0.50 Casting:2560-D Perimeter (ft):5.10 Open Area (sf):1.00 Solve For Qi Allowable: Note: Formulas Obtained From Neenah Foundry Company Inlet Capacity Worksheets Transitional Flow Eqn: Qi = ((QOrifice + QWeir)/2) x .80 = ((1.7+3)/2) x .80 = 1.7 cfs Orifice Flow Eqn:Weir Flow Eqn: Qi =[( 0.6)(A)(Pp)] x [(2)(g)(h)]1/2 Qi =3.3(P)(Pp)(dw)1.5 Where:Where: Qi = Inlet Capacity (CFS)Qi = Inlet Capacity (CFS) A = Fee open area of grate (sf)P = Perimeter of Grate Opening (ft) g = 32.2 (ft per sec/sec)dw = Depth Of Water Above Grate h = Head (ft) (Water Depth)Pp = Percent Plugged Pp = Percent Plugged Qi =1.7 cfs allowable Qi =Use Orifice Flow Equation 1.7 1.7 3.00 Allowable Inlet Flow = 1.7 cfs Solve For Q Actual: Rational Formula:Q10 = C x I x A Where: Q10 = Flow from 10 year storm event C = Runoff Coefficient (unitless) I = Rainfall intensity (in/hr) A = Watershed area (ac) C =0.20 I =6.12 in/hr T.C. =5.0 min A =0.10 ac 0.1 Actual Inlet Flow = 0.1 cfs Q Comparison Result:Casting Is Sufficient Note: At this depth, transitional flow is anticipated. The allowable inlet flow shown is 80% of the average of the weir and orifice flow due to vortex action. This adjustment value obtained from Neenah Foundry technical division. Discharge vs. Depth on Grate Calculation For Inlets In Sag Conditions CEG WRN WTP Expansion STR-8 23-Apr-25 APPENDIX E: SITE RUNOFF CALCULATIONS G ra ss Concrete G ra vel 6" C R A B . 1 0 " S P R U C E 1 5 " P IN E 8" S A S S. 2 7 " S A S S A F R A S 2 4 " T W IN P IN E 1 2 " D E A D 1 0 " P IN E 1 5 " P IN E 4" S A S S. 1 2 " P IN E 6" G IN K G O S A F E T Y S W IT C H 15" RCP 1 2 " S T E E L 12" R CP S T R . #1 T C : 7 4 8 .8 8 F R O M N O R T H : 7 4 5 .6 3 F R O M N E : 7 3 9.3 9 T O N W : 7 3 9 .3 8 12" RCP 15" R CP 15" RCP S T O R M M H T C : 7 4 0 .3 8 T O N E : 7 3 5.8 2 F R O M S E : 7 3 5.9 2 F R O M S W : 7 3 6.1 5 S T R . #4 T C : 7 4 9 .6 5 T O S W : 7 4 8 .0 2 12" CMP S T R . #5 T C : 7 3 9 .4 0 (N O P I P E S V I S I B L E ) 4 8 " R CP S T R . #6 T C : 7 4 5 .0 5 F R O M S W : 7 3 1.1 5 T O N O R T H : 7 3 1.0 0 6 " P V C S T R . #7 T C : 7 4 4 .9 2 F R O M N O R T H : 7 4 1 .0 1 F R O M S W : 7 3 0.4 8 48" R CP 48" R CP 8 " P V C 8 " P V C S T R . #8 T C : 7 4 4 .9 2 T O E A S T : 7 4 0 .0 2 4 8" R CP S T R . #9 T C : 7 4 5 .4 5 F R O M S W : 7 3 1.0 1 F R O M W E S T : 7 3 9 .9 3 T O N E : 7 2 9.6 6 54" RCP 3 6 " R C P 3 6 " R C P S T R . #1 0 T C : 7 4 3 .4 2 F R O M S W : 7 2 9.3 2 F R O M W E S T : 7 3 1 .3 7 T O N E : 7 2 9.3 0 5 4" R C P S T R . #1 1 T C : 7 4 3 .3 0 F R O M S W : 7 2 9.0 9 T O E A S T : 7 2 9 .0 7 S T R . #1 2 T C : 7 4 3 .1 9 T O E A S T : 7 3 2 .8 0 (N O O T H E R P I P E S V I S IB L E ) 12" Steel E L E C T RIC U TILIT Y T R A N S F O R ME R R O O F D R A IN I N V E L 7 4 4 .5 0 6" PV C R O O F D R AIN 224.00' (D) S 31°10'00"W 210.50' (D) P U M P S T A TIO N 2" F O R C E M A IN S 34°05'00"W S 31°10'00"W 210.50' (D) 4 2 " S T O R M S E W E R S T O R M I N L E T R I M E L . 7 3 6 .7 0 I .E . 7 3 1.1 8 3 /4 " G A S L I N E S t o r m I nle t T C : 7 4 4 .0 0 I n v : 7 4 1.0 0 S T O R M M H T C : 7 3 9 .3 8 T O N E : 7 3 3.6 3 1 3 1 5.2 8 ' (D ) 1 315.47' (M)S 7 5°3 4 '4 4" E 1480.0' (D ) S 76 °4 2 '0 7" E 2 71.29' (M) S 76 °3 5 '03 " E 271.47' (D) S 7 4°4 0 '0 0 " E 645.92' (D ) W OHU OHU OHU OHU OHU O H U G G G G G G G 0 60 120 FEET SCALE:1"=60' DESIGNED BY: PROJECT NO.: DATE:APRIL 2025 CONSULTANTS SEALS NO.ISSUED FORDATE BY DRAWN BY: CHECKED BY: COPYRIGHT: SHEET TITLE 1 2 3 4 5 6 A B C D E User:NVERGATOS Spec:AUS-NCSMOD File:K:\CIVIL PROJECTS\2024\24JPSC56 CEG WRN TREATMENT PLAN\DRAWINGS\BASINS.DWG Scale:1:1 SavedDate:4/23/2025 Time:09:25 Plot Date: Nick Vergatos; 4/23/2025; 11:35 ; Layout:PRE 30239923 WHITE RIVER NORTH WTP EXPANSION ARCADIS U.S., INC., 2023 SHEET NO.: SCALE: ISSUE STATUS: PERMIT SET LEGAL ENTITY: ARCADIS U.S., INC. 0 1 BAR IS ONE INCH ON UNREDUCED DRAWING SHEET TITLE NBV CLM NBV AS NOTED PRE DEVELOPED BASIN PRE PRE DEVELOPED BASIN TOTAL: 7.68ac IMPERVIOUS: 0.68ac PERVIOUS: 7.00ac 6" C R A B . 1 0 " S P R U C E 1 5 " P IN E 8" S A S S. 2 7 " S A S S A F R A S 2 4 " T W IN P IN E 1 2 " D E A D 1 0 " P IN E 1 5 " P IN E 4" S A S S. 1 2 " P IN E 6" G IN K G O S A F E T Y S W IT C H 15" RCP 1 2 " S T E E L 12" R CP S T R . #1 T C : 7 4 8 .8 8 F R O M N O R T H : 7 4 5 .6 3 F R O M N E : 7 3 9.3 9 T O N W : 7 3 9 .3 8 12" RCP 15" R CP 15" RCP S T O R M M H T C : 7 4 0 .3 8 T O N E : 7 3 5.8 2 F R O M S E : 7 3 5.9 2 F R O M S W : 7 3 6.1 5 S T R . #4 T C : 7 4 9 .6 5 T O S W : 7 4 8 .0 2 12" CMP S T R . #5 T C : 7 3 9 .4 0 (N O P I P E S V I S I B L E ) 4 8 " R CP S T R . #6 T C : 7 4 5 .0 5 F R O M S W : 7 3 1.1 5 T O N O R T H : 7 3 1.0 0 6 " P V C S T R . #7 T C : 7 4 4 .9 2 F R O M N O R T H : 7 4 1 .0 1 F R O M S W : 7 3 0.4 8 48" R CP 48" R CP 8 " P V C 8 " P V C S T R . #8 T C : 7 4 4 .9 2 T O E A S T : 7 4 0 .0 2 4 8" R CP S T R . #9 T C : 7 4 5 .4 5 F R O M S W : 7 3 1.0 1 F R O M W E S T : 7 3 9 .9 3 T O N E : 7 2 9.6 6 54" RCP 3 6 " R C P 3 6 " R C P S T R . #1 0 T C : 7 4 3 .4 2 F R O M S W : 7 2 9.3 2 F R O M W E S T : 7 3 1 .3 7 T O N E : 7 2 9.3 0 5 4" R C P S T R . #1 1 T C : 7 4 3 .3 0 F R O M S W : 7 2 9.0 9 T O E A S T : 7 2 9 .0 7 S T R . #1 2 T C : 7 4 3 .1 9 T O E A S T : 7 3 2 .8 0 (N O O T H E R P I P E S V I S IB L E ) 12" Steel E L E C T RIC U TILIT Y T R A N S F O R ME R R O O F D R A IN I N V E L 7 4 4 .5 0 6" PV C R O O F D R AIN 224.00' (D) S 31°10'00"W 210.50' (D) P U M P S T A TIO N 2" F O R C E M A IN S 34°05'00"W S 31°10'00"W 210.50' (D) 4 2 " S T O R M S E W E R S T O R M I N L E T R I M E L . 7 3 6 .7 0 I .E . 7 3 1.1 8 3 /4 " G A S L I N E S t o r m I nle t T C : 7 4 4 .0 0 I n v : 7 4 1.0 0 S T O R M M H T C : 7 3 9 .3 8 T O N E : 7 3 3.6 3 1 3 1 5.2 8 ' (D ) 1 315.47' (M)S 7 5°3 4 '4 4" E 1480.0' (D ) S 76 °4 2 '0 7" E 2 71.29' (M) S 76 °3 5 '03 " E 271.47' (D) S 7 4°4 0 '0 0 " E 645.92' (D ) W OHU OHU OHU OHU OHU O H U G G G G G G G 6 PAC SILO PAC SILO STR-1 STR-2 STR-3 STR-4 STR-5 STR-6 STR-7 STR-8 BASIN 8 TOTAL: 0.10ac IMP: 0.00ac PER: 0.10ac BASIN 3 TOTAL: 0.24ac IMP: 0.05ac PER: 0.19ac BASIN 2 TOTAL: 0.06ac IMP: 0.00ac PER: 0.06ac BASIN 4 TOTAL: 0.32ac IMP: 0.09ac PER: 0.23ac BASIN 5 TOTAL: 0.08ac IMP: 0.02ac PER: 0.06ac BASIN 6 TOTAL: 0.05ac IMP: 0.00ac PER: 0.05ac BASIN 7 TOTAL: 0.07ac IMP: 0.02ac PER: 0.05ac BASIN 1 TOTAL: 0.20ac IMP: 0.00ac PER: 0.20ac 0 60 120 FEET SCALE:1"=60' DESIGNED BY: PROJECT NO.: DATE:APRIL 2025 CONSULTANTS SEALS NO.ISSUED FORDATE BY DRAWN BY: CHECKED BY: COPYRIGHT: SHEET TITLE 1 2 3 4 5 6 A B C D E User:NVERGATOS Spec:AUS-NCSMOD File:K:\CIVIL PROJECTS\2024\24JPSC56 CEG WRN TREATMENT PLAN\DRAWINGS\BASINS.DWG Scale:1:1 SavedDate:4/23/2025 Time:13:10 Plot Date: Nick Vergatos; 4/23/2025; 16:51 ; Layout:POST 30239923 WHITE RIVER NORTH WTP EXPANSION ARCADIS U.S., INC., 2023 SHEET NO.: SCALE: ISSUE STATUS: PERMIT SET LEGAL ENTITY: ARCADIS U.S., INC. 0 1 BAR IS ONE INCH ON UNREDUCED DRAWING SHEET TITLE NBV CLM NBV AS NOTED POST DEVELOPED BASIN POST POST DEVELOPED BASIN TOTAL: 7.68ac OPEN TOP BASINS: 1.28ac EFFECTIVE DRAINAGE AREA:6.40ac IMPERVIOUS: 1.18ac PERVIOUS: 5.22ac EXISTING CONDITIONS: CEG White River North WTP Expansion Using Rational Method, Q=CiA Basin Area, A (ac) = 7.68 Land Use Area x Coefficient =CA Pavement 0.68 0.85 0.58 Grass 7.00 0.20 1.40 Roof 0.00 0.90 0.00 7.680 acres Cavg =0.26 Time of Concentration, T Overland Flow n = 0.15 L (ft) = 100 S (ft/ft) = 0.040 Tt =8.16 minutes 5 0.15 Shallow Concentrated Flow S (ft/ft) =0.050 1 V (fps) = 16.1315 x S^0.5 = 3.61 3.61 L (ft) =80 Tt =0.37 Ttotal =8.53 minutes IDF Equation Values a b N 2yr 32.852 7 0.778 i2y =3.89 10yr 56.974 9 0.7953 i10yr =5.84 100yr 92.718 11 0.8145 i100yr =8.24 Q=CiA C I A Q Q2yr =0.26 3.89 7.68 7.69 cfs Q10yr =0.26 5.84 7.68 11.55 cfs Q100yr =0.26 8.24 7.68 16.30 cfs Runoff, Q Runoff Coefficient, C Rainfall Intensity, I (in/hr) x x x 60xS )nL(0043.0T 4.0 8.0 t = V60 LTt= N)bt( ai+= = = = x x x x =x Surface Type Unpaved Paved PROPOSED CONDITIONS: CEG White River North WTP Expansion Using Rational Method, Q=CiA Basin Area, A (ac) = 6.40 Land Use Area x Coefficient =CA Pavement 1.18 0.85 1.00 Grass 5.22 0.20 1.04 Roof 0.00 0.90 0.00 6.400 acres Cavg =0.32 Time of Concentration, T Overland Flow n = 0.15 L (ft) = 93 S (ft/ft) = 0.080 Tt =5.84 minutes 5 0.15 Shallow Concentrated Flow S (ft/ft) = 2 0 L (ft) = Tt =0.00 Ttotal =5.84 minutes IDF Equation Values a b N 2yr 32.852 7 0.778 i2y =4.51 10yr 56.974 9 0.7953 i10yr =6.67 100yr 92.718 11 0.8145 i100yr =9.30 Q=CiA C I A Q Q2yr =0.32 4.51 6.40 9.23 cfs Q10yr =0.32 6.67 6.40 13.65 cfs Q100yr =0.32 9.30 6.40 19.03 cfs Change in Runoff Increasing or Qpre - Qpost = Decreasing Runoff? Q2yr =9.23 7.69 1.54 cfs Increasing Q10yr =13.65 11.55 2.10 cfs Increasing Q100yr =19.03 16.30 2.74 cfs Increasing Runoff, Q Runoff Coefficient, C Rainfall Intensity, I (in/hr) 60xS )nL(0043.0T 4.0 8.0 t = V60 LTt= x x x = = = x x x x =x - - - = = = V60 LTt= Unpaved Paved N)bt( ai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°3 4 '4 4 " E 1 4 8 0 .0 ' (D ) S 7 6 °4 2 '0 7 " E 2 7 1 .2 9 ' (M ) S 7 6 °3 5 '0 3 " E 2 7 1 .4 7 ' (D ) CHEM CHEM 6 STR-1 STR-6 STR-7 0 60 120 FEET SCALE:1"=60' DESIGNED BY: PROJECT NO.: DATE:APRIL 2025 CONSULTANTS SEALS NO.ISSUED FORDATE BY DRAWN BY: CHECKED BY: COPYRIGHT: SHEET TITLE 1 2 3 4 5 6 A B C D E User:NVERGATOS Spec:AUS-NCSMOD File:K:\CIVIL PROJECTS\2024\24JPSC56 CEG WRN TREATMENT PLAN\DRAWINGS\BASINS.DWG Scale:1:1 SavedDate:4/23/2025 Time:09:25 Plot Date: Nick Vergatos; 4/23/2025; 11:40 ; Layout:WQ 30239923 WHITE RIVER NORTH WTP EXPANSION ARCADIS U.S., INC., 2023 SHEET NO.: SCALE: ISSUE STATUS: PERMIT SET LEGAL ENTITY: ARCADIS U.S., INC. 0 1 BAR IS ONE INCH ON UNREDUCED DRAWING SHEET TITLE NBV CLM NBV AS NOTED POST DEVELOPED BASIN POST AREA TO WATER QUALITY BASIN TOTAL: 2.47ac IMPERVIOUS: 2.46ac PERVIOUS: 5.22ac N E W W A T E R Q U A LIT Y B A SIN 1S Developed Basin 2P Underground Detention Routing Diagram for CEG WRN- Basin Calculations Prepared by JPS Consulting Engineers, Printed 4/23/2025 HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Subcat Reach Pond Link CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 2HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 year storm Type II 24-hr Default 24.00 1 2.70 2 2 10 year storm Type II 24-hr Default 24.00 1 3.80 2 CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 3HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 5.220 74 >75% Grass cover, Good, HSG C (1S) 2.460 98 Paved parking, HSG D (1S) 7.680 82 TOTAL AREA CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 4HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 0.000 HSG B 5.220 HSG C 1S 2.460 HSG D 1S 0.000 Other 7.680 TOTAL AREA CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 5HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 0.000 5.220 0.000 0.000 5.220 >75% Grass cover, Good 1S 0.000 0.000 0.000 2.460 0.000 2.460 Paved parking 1S 0.000 0.000 5.220 2.460 0.000 7.680 TOTAL AREA Type II 24-hr 2 year storm Rainfall=2.70"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 6HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=7.680 ac 32.03% Impervious Runoff Depth>1.14"Subcatchment 1S: Developed Basin Tc=10.0 min CN=82 Runoff=13.31 cfs 0.732 af Peak Elev=742.88' Storage=31,885 cf Inflow=13.31 cfs 0.732 afPond 2P: Underground Detention Outflow=0.00 cfs 0.000 af Total Runoff Area = 7.680 ac Runoff Volume = 0.732 af Average Runoff Depth = 1.14" 67.97% Pervious = 5.220 ac 32.03% Impervious = 2.460 ac Type II 24-hr 2 year storm Rainfall=2.70"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 7HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Developed Basin Runoff =13.31 cfs @ 12.02 hrs, Volume=0.732 af, Depth> 1.14" Routed to Pond 2P : Underground Detention Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 2 year storm Rainfall=2.70" Area (ac) CN Description 2.460 98 Paved parking, HSG D 5.220 74 >75% Grass cover, Good, HSG C 7.680 82 Weighted Average 5.220 67.97% Pervious Area 2.460 32.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Subcatchment 1S: Developed Basin Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 2 year storm Rainfall=2.70" Runoff Area=7.680 ac Runoff Volume=0.732 af Runoff Depth>1.14" Tc=10.0 min CN=82 13.31 cfs Type II 24-hr 2 year storm Rainfall=2.70"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 8HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Hydrograph for Subcatchment 1S: Developed Basin Time (hours) Precip. (inches) Excess (inches) Runoff (cfs) 0.00 0.00 0.00 0.00 0.25 0.01 0.00 0.00 0.50 0.01 0.00 0.00 0.75 0.02 0.00 0.00 1.00 0.03 0.00 0.00 1.25 0.04 0.00 0.00 1.50 0.04 0.00 0.00 1.75 0.05 0.00 0.00 2.00 0.06 0.00 0.00 2.25 0.07 0.00 0.00 2.50 0.08 0.00 0.00 2.75 0.08 0.00 0.00 3.00 0.09 0.00 0.00 3.25 0.10 0.00 0.00 3.50 0.11 0.00 0.00 3.75 0.12 0.00 0.00 4.00 0.13 0.00 0.00 4.25 0.14 0.00 0.00 4.50 0.15 0.00 0.00 4.75 0.16 0.00 0.00 5.00 0.17 0.00 0.00 5.25 0.18 0.00 0.00 5.50 0.19 0.00 0.00 5.75 0.20 0.00 0.00 6.00 0.22 0.00 0.00 6.25 0.23 0.00 0.00 6.50 0.24 0.00 0.00 6.75 0.25 0.00 0.00 7.00 0.27 0.00 0.00 7.25 0.28 0.00 0.00 7.50 0.29 0.00 0.00 7.75 0.31 0.00 0.00 8.00 0.32 0.00 0.00 8.25 0.34 0.00 0.00 8.50 0.36 0.00 0.00 8.75 0.38 0.00 0.00 9.00 0.40 0.00 0.00 9.25 0.42 0.00 0.00 9.50 0.44 0.00 0.00 9.75 0.46 0.00 0.01 10.00 0.49 0.00 0.02 10.25 0.52 0.00 0.05 10.50 0.55 0.01 0.08 10.75 0.59 0.01 0.12 11.00 0.63 0.02 0.19 11.25 0.69 0.03 0.29 11.50 0.76 0.04 0.47 11.75 1.04 0.13 2.24 12.00 1.79 0.51 13.06 12.25 1.91 0.59 3.16 12.50 1.98 0.64 1.66 12.75 2.04 0.67 1.15 13.00 2.08 0.70 0.96 13.25 2.12 0.73 0.83 Time (hours) Precip. (inches) Excess (inches) Runoff (cfs) 13.50 2.16 0.75 0.73 13.75 2.19 0.78 0.65 14.00 2.21 0.79 0.58 14.25 2.24 0.81 0.53 14.50 2.26 0.83 0.51 14.75 2.28 0.84 0.48 15.00 2.30 0.86 0.46 15.25 2.32 0.87 0.43 15.50 2.34 0.88 0.41 15.75 2.36 0.90 0.39 16.00 2.38 0.91 0.36 16.25 2.39 0.92 0.34 16.50 2.41 0.93 0.33 16.75 2.42 0.94 0.33 17.00 2.43 0.95 0.32 17.25 2.45 0.96 0.31 17.50 2.46 0.97 0.30 17.75 2.47 0.98 0.29 18.00 2.49 0.99 0.28 18.25 2.50 1.00 0.27 18.50 2.51 1.01 0.26 18.75 2.52 1.01 0.25 19.00 2.53 1.02 0.24 19.25 2.54 1.03 0.24 19.50 2.55 1.04 0.23 19.75 2.56 1.04 0.22 20.00 2.57 1.05 0.21 20.25 2.58 1.06 0.20 20.50 2.59 1.06 0.20 20.75 2.60 1.07 0.20 21.00 2.60 1.08 0.20 21.25 2.61 1.08 0.19 21.50 2.62 1.09 0.19 21.75 2.63 1.09 0.19 22.00 2.64 1.10 0.19 22.25 2.65 1.11 0.19 22.50 2.65 1.11 0.19 22.75 2.66 1.12 0.18 23.00 2.67 1.12 0.18 23.25 2.68 1.13 0.18 23.50 2.68 1.14 0.18 23.75 2.69 1.14 0.18 24.00 2.70 1.15 0.18 Type II 24-hr 2 year storm Rainfall=2.70"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 9HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Summary for Pond 2P: Underground Detention Inflow Area =7.680 ac, 32.03% Impervious, Inflow Depth > 1.14" for 2 year storm event Inflow =13.31 cfs @ 12.02 hrs, Volume=0.732 af Outflow =0.00 cfs @ 0.00 hrs, Volume=0.000 af, Atten= 100%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 742.88' @ 24.00 hrs Surf.Area= 38,508 sf Storage= 31,885 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 742.00'77,766 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 742.00 34,065 1,057.0 0 0 34,065 743.00 39,139 1,096.0 36,573 36,573 40,833 744.00 43,282 1,133.0 41,193 77,766 47,490 Pond 2P: Underground Detention Inflow Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=7.680 ac Peak Elev=742.88' Storage=31,885 cf 13.31 cfs Type II 24-hr 2 year storm Rainfall=2.70"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 10HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Pond 2P: Underground Detention Total Stage-Discharge Discharge (cfs) 0 El e v a t i o n ( f e e t ) 744 743 742 Pond 2P: Underground Detention Surface Storage Stage-Area-Storage Storage (cubic-feet) 70,00060,00050,00040,00030,00020,00010,0000 Surface/Horizontal/Wetted Area (sq-ft) 40,00035,00030,00025,00020,00015,00010,0005,0000 El e v a t i o n ( f e e t ) 744 743 742 Custom Stage Data Type II 24-hr 2 year storm Rainfall=2.70"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 11HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Hydrograph for Pond 2P: Underground Detention Time (hours) Inflow (cfs) Storage (cubic-feet) Elevation (feet) 0.00 0.00 0 742.00 0.25 0.00 0 742.00 0.50 0.00 0 742.00 0.75 0.00 0 742.00 1.00 0.00 0 742.00 1.25 0.00 0 742.00 1.50 0.00 0 742.00 1.75 0.00 0 742.00 2.00 0.00 0 742.00 2.25 0.00 0 742.00 2.50 0.00 0 742.00 2.75 0.00 0 742.00 3.00 0.00 0 742.00 3.25 0.00 0 742.00 3.50 0.00 0 742.00 3.75 0.00 0 742.00 4.00 0.00 0 742.00 4.25 0.00 0 742.00 4.50 0.00 0 742.00 4.75 0.00 0 742.00 5.00 0.00 0 742.00 5.25 0.00 0 742.00 5.50 0.00 0 742.00 5.75 0.00 0 742.00 6.00 0.00 0 742.00 6.25 0.00 0 742.00 6.50 0.00 0 742.00 6.75 0.00 0 742.00 7.00 0.00 0 742.00 7.25 0.00 0 742.00 7.50 0.00 0 742.00 7.75 0.00 0 742.00 8.00 0.00 0 742.00 8.25 0.00 0 742.00 8.50 0.00 0 742.00 8.75 0.00 0 742.00 9.00 0.00 0 742.00 9.25 0.00 0 742.00 9.50 0.00 0 742.00 9.75 0.01 2 742.00 10.00 0.02 15 742.00 10.25 0.05 46 742.00 10.50 0.08 102 742.00 10.75 0.12 192 742.01 11.00 0.19 331 742.01 11.25 0.29 542 742.02 11.50 0.47 881 742.03 11.75 2.24 1,767 742.05 12.00 13.06 7,671 742.22 12.25 3.16 14,974 742.43 12.50 1.66 16,976 742.48 12.75 1.15 18,190 742.51 13.00 0.96 19,137 742.54 13.25 0.83 19,937 742.56 Time (hours) Inflow (cfs) Storage (cubic-feet) Elevation (feet) 13.50 0.73 20,638 742.58 13.75 0.65 21,257 742.60 14.00 0.58 21,810 742.61 14.25 0.53 22,305 742.63 14.50 0.51 22,771 742.64 14.75 0.48 23,216 742.65 15.00 0.46 23,639 742.66 15.25 0.43 24,041 742.67 15.50 0.41 24,421 742.68 15.75 0.39 24,780 742.69 16.00 0.36 25,116 742.70 16.25 0.34 25,431 742.71 16.50 0.33 25,735 742.72 16.75 0.33 26,031 742.73 17.00 0.32 26,320 742.73 17.25 0.31 26,601 742.74 17.50 0.30 26,874 742.75 17.75 0.29 27,139 742.75 18.00 0.28 27,396 742.76 18.25 0.27 27,645 742.77 18.50 0.26 27,886 742.77 18.75 0.25 28,118 742.78 19.00 0.24 28,343 742.79 19.25 0.24 28,559 742.79 19.50 0.23 28,767 742.80 19.75 0.22 28,966 742.80 20.00 0.21 29,158 742.81 20.25 0.20 29,341 742.81 20.50 0.20 29,521 742.82 20.75 0.20 29,700 742.82 21.00 0.20 29,878 742.83 21.25 0.19 30,053 742.83 21.50 0.19 30,228 742.84 21.75 0.19 30,400 742.84 22.00 0.19 30,572 742.85 22.25 0.19 30,741 742.85 22.50 0.19 30,909 742.85 22.75 0.18 31,076 742.86 23.00 0.18 31,241 742.86 23.25 0.18 31,404 742.87 23.50 0.18 31,566 742.87 23.75 0.18 31,726 742.88 24.00 0.18 31,885 742.88 Type II 24-hr 10 year storm Rainfall=3.80"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 12HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=7.680 ac 32.03% Impervious Runoff Depth>2.03"Subcatchment 1S: Developed Basin Tc=10.0 min CN=82 Runoff=23.63 cfs 1.298 af Peak Elev=743.50' Storage=56,527 cf Inflow=23.63 cfs 1.298 afPond 2P: Underground Detention Outflow=0.00 cfs 0.000 af Total Runoff Area = 7.680 ac Runoff Volume = 1.298 af Average Runoff Depth = 2.03" 67.97% Pervious = 5.220 ac 32.03% Impervious = 2.460 ac Type II 24-hr 10 year storm Rainfall=3.80"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 13HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Developed Basin Runoff =23.63 cfs @ 12.02 hrs, Volume=1.298 af, Depth> 2.03" Routed to Pond 2P : Underground Detention Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10 year storm Rainfall=3.80" Area (ac) CN Description 2.460 98 Paved parking, HSG D 5.220 74 >75% Grass cover, Good, HSG C 7.680 82 Weighted Average 5.220 67.97% Pervious Area 2.460 32.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Subcatchment 1S: Developed Basin Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Type II 24-hr 10 year storm Rainfall=3.80" Runoff Area=7.680 ac Runoff Volume=1.298 af Runoff Depth>2.03" Tc=10.0 min CN=82 23.63 cfs Type II 24-hr 10 year storm Rainfall=3.80"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 14HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Hydrograph for Subcatchment 1S: Developed Basin Time (hours) Precip. (inches) Excess (inches) Runoff (cfs) 0.00 0.00 0.00 0.00 0.25 0.01 0.00 0.00 0.50 0.02 0.00 0.00 0.75 0.03 0.00 0.00 1.00 0.04 0.00 0.00 1.25 0.05 0.00 0.00 1.50 0.06 0.00 0.00 1.75 0.07 0.00 0.00 2.00 0.08 0.00 0.00 2.25 0.10 0.00 0.00 2.50 0.11 0.00 0.00 2.75 0.12 0.00 0.00 3.00 0.13 0.00 0.00 3.25 0.14 0.00 0.00 3.50 0.16 0.00 0.00 3.75 0.17 0.00 0.00 4.00 0.18 0.00 0.00 4.25 0.20 0.00 0.00 4.50 0.21 0.00 0.00 4.75 0.22 0.00 0.00 5.00 0.24 0.00 0.00 5.25 0.25 0.00 0.00 5.50 0.27 0.00 0.00 5.75 0.29 0.00 0.00 6.00 0.30 0.00 0.00 6.25 0.32 0.00 0.00 6.50 0.34 0.00 0.00 6.75 0.36 0.00 0.00 7.00 0.38 0.00 0.00 7.25 0.40 0.00 0.00 7.50 0.42 0.00 0.00 7.75 0.44 0.00 0.00 8.00 0.46 0.00 0.00 8.25 0.48 0.00 0.02 8.50 0.50 0.00 0.03 8.75 0.53 0.00 0.05 9.00 0.56 0.01 0.08 9.25 0.59 0.01 0.10 9.50 0.62 0.01 0.12 9.75 0.65 0.02 0.15 10.00 0.69 0.03 0.20 10.25 0.73 0.03 0.25 10.50 0.78 0.04 0.33 10.75 0.83 0.06 0.43 11.00 0.89 0.08 0.57 11.25 0.97 0.10 0.79 11.50 1.08 0.14 1.15 11.75 1.47 0.33 4.82 12.00 2.52 1.01 23.36 12.25 2.68 1.13 5.34 12.50 2.79 1.22 2.74 12.75 2.87 1.28 1.89 13.00 2.93 1.33 1.58 13.25 2.99 1.37 1.35 Time (hours) Precip. (inches) Excess (inches) Runoff (cfs) 13.50 3.04 1.41 1.19 13.75 3.08 1.44 1.05 14.00 3.12 1.47 0.94 14.25 3.15 1.50 0.86 14.50 3.18 1.52 0.82 14.75 3.21 1.55 0.78 15.00 3.24 1.57 0.74 15.25 3.27 1.60 0.70 15.50 3.30 1.62 0.66 15.75 3.32 1.64 0.62 16.00 3.34 1.65 0.58 16.25 3.37 1.67 0.55 16.50 3.39 1.69 0.53 16.75 3.41 1.71 0.52 17.00 3.43 1.72 0.50 17.25 3.45 1.74 0.49 17.50 3.46 1.75 0.48 17.75 3.48 1.77 0.46 18.00 3.50 1.78 0.45 18.25 3.52 1.80 0.43 18.50 3.53 1.81 0.42 18.75 3.55 1.82 0.40 19.00 3.56 1.84 0.39 19.25 3.58 1.85 0.37 19.50 3.59 1.86 0.36 19.75 3.60 1.87 0.34 20.00 3.62 1.88 0.33 20.25 3.63 1.89 0.32 20.50 3.64 1.90 0.31 20.75 3.65 1.91 0.31 21.00 3.67 1.92 0.31 21.25 3.68 1.93 0.31 21.50 3.69 1.94 0.30 21.75 3.70 1.95 0.30 22.00 3.71 1.96 0.30 22.25 3.72 1.97 0.30 22.50 3.74 1.98 0.29 22.75 3.75 1.99 0.29 23.00 3.76 2.00 0.29 23.25 3.77 2.01 0.28 23.50 3.78 2.02 0.28 23.75 3.79 2.02 0.28 24.00 3.80 2.03 0.27 Type II 24-hr 10 year storm Rainfall=3.80"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 15HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Summary for Pond 2P: Underground Detention Inflow Area =7.680 ac, 32.03% Impervious, Inflow Depth > 2.03" for 10 year storm event Inflow =23.63 cfs @ 12.02 hrs, Volume=1.298 af Outflow =0.00 cfs @ 0.00 hrs, Volume=0.000 af, Atten= 100%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 743.50' @ 24.00 hrs Surf.Area= 41,172 sf Storage= 56,527 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 742.00'77,766 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 742.00 34,065 1,057.0 0 0 34,065 743.00 39,139 1,096.0 36,573 36,573 40,833 744.00 43,282 1,133.0 41,193 77,766 47,490 Pond 2P: Underground Detention Inflow Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=7.680 ac Peak Elev=743.50' Storage=56,527 cf 23.63 cfs Type II 24-hr 10 year storm Rainfall=3.80"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 16HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Pond 2P: Underground Detention Total Stage-Discharge Discharge (cfs) 0 El e v a t i o n ( f e e t ) 744 743 742 Pond 2P: Underground Detention Surface Storage Stage-Area-Storage Storage (cubic-feet) 70,00060,00050,00040,00030,00020,00010,0000 Surface/Horizontal/Wetted Area (sq-ft) 40,00035,00030,00025,00020,00015,00010,0005,0000 El e v a t i o n ( f e e t ) 744 743 742 Custom Stage Data Type II 24-hr 10 year storm Rainfall=3.80"CEG WRN- Basin Calculations Printed 4/23/2025Prepared by JPS Consulting Engineers Page 17HydroCAD® 10.20-4c s/n 13006 © 2024 HydroCAD Software Solutions LLC Hydrograph for Pond 2P: Underground Detention Time (hours) Inflow (cfs) Storage (cubic-feet) Elevation (feet) 0.00 0.00 0 742.00 0.25 0.00 0 742.00 0.50 0.00 0 742.00 0.75 0.00 0 742.00 1.00 0.00 0 742.00 1.25 0.00 0 742.00 1.50 0.00 0 742.00 1.75 0.00 0 742.00 2.00 0.00 0 742.00 2.25 0.00 0 742.00 2.50 0.00 0 742.00 2.75 0.00 0 742.00 3.00 0.00 0 742.00 3.25 0.00 0 742.00 3.50 0.00 0 742.00 3.75 0.00 0 742.00 4.00 0.00 0 742.00 4.25 0.00 0 742.00 4.50 0.00 0 742.00 4.75 0.00 0 742.00 5.00 0.00 0 742.00 5.25 0.00 0 742.00 5.50 0.00 0 742.00 5.75 0.00 0 742.00 6.00 0.00 0 742.00 6.25 0.00 0 742.00 6.50 0.00 0 742.00 6.75 0.00 0 742.00 7.00 0.00 0 742.00 7.25 0.00 0 742.00 7.50 0.00 0 742.00 7.75 0.00 0 742.00 8.00 0.00 1 742.00 8.25 0.02 9 742.00 8.50 0.03 30 742.00 8.75 0.05 67 742.00 9.00 0.08 126 742.00 9.25 0.10 207 742.01 9.50 0.12 310 742.01 9.75 0.15 433 742.01 10.00 0.20 590 742.02 10.25 0.25 791 742.02 10.50 0.33 1,052 742.03 10.75 0.43 1,388 742.04 11.00 0.57 1,834 742.05 11.25 0.79 2,430 742.07 11.50 1.15 3,296 742.10 11.75 4.82 5,303 742.15 12.00 23.36 16,533 742.47 12.25 5.34 29,250 742.81 12.50 2.74 32,595 742.90 12.75 1.89 34,597 742.95 13.00 1.58 36,151 742.99 13.25 1.35 37,457 743.02 Time (hours) Inflow (cfs) Storage (cubic-feet) Elevation (feet) 13.50 1.19 38,598 743.05 13.75 1.05 39,603 743.08 14.00 0.94 40,498 743.10 14.25 0.86 41,299 743.12 14.50 0.82 42,050 743.14 14.75 0.78 42,766 743.16 15.00 0.74 43,447 743.17 15.25 0.70 44,093 743.19 15.50 0.66 44,702 743.21 15.75 0.62 45,276 743.22 16.00 0.58 45,813 743.23 16.25 0.55 46,317 743.25 16.50 0.53 46,802 743.26 16.75 0.52 47,275 743.27 17.00 0.50 47,735 743.28 17.25 0.49 48,182 743.29 17.50 0.48 48,616 743.30 17.75 0.46 49,037 743.31 18.00 0.45 49,445 743.32 18.25 0.43 49,840 743.33 18.50 0.42 50,222 743.34 18.75 0.40 50,591 743.35 19.00 0.39 50,947 743.36 19.25 0.37 51,289 743.37 19.50 0.36 51,618 743.38 19.75 0.34 51,933 743.38 20.00 0.33 52,235 743.39 20.25 0.32 52,525 743.40 20.50 0.31 52,809 743.41 20.75 0.31 53,091 743.41 21.00 0.31 53,371 743.42 21.25 0.31 53,648 743.43 21.50 0.30 53,923 743.43 21.75 0.30 54,195 743.44 22.00 0.30 54,464 743.45 22.25 0.30 54,731 743.45 22.50 0.29 54,995 743.46 22.75 0.29 55,257 743.47 23.00 0.29 55,516 743.47 23.25 0.28 55,773 743.48 23.50 0.28 56,027 743.48 23.75 0.28 56,278 743.49 24.00 0.27 56,527 743.50 APPENDIX F: STORMWATER QUALITY WAIVER REQUEST CONSULTING ENGINEERS 9365 Counselors Row, Suite 116, Indianapolis, IN 46240 23 April 2025 City of Carmel Board of Public Works 1000 S Rangeline Rd Carmel, IN 46032 Re: Citizens Energy Group White River North Water Treatment Plant Expansion Project 11825 River Rd Carmel, IN 46033 Waiver Request from the Stormwater Quality Requirement in the Carmel Stormwater Technical Standards Manual The above referenced project is seeking a waiver from the requirement to provide stormwater quality measures for the proposed construction as outlined in the technical standards manual. Given the nature of the site and the proposed construction, it is impractical to meet the requirements given the large number of underground utilities and critical infrastructure that exist on the site and that the project area is spread out unconnected across the plant. A good faith attempt at stormwater quality is being proposed as follows. The project will utilizes a majority of grass and natural filter areas across a majority of the site prior to water entering into any stormwater system. The largest area of new hardscape is on the northeast of the property. This area will be routed into a basin that is currently used to treat and dry residuals from the water treatment process. With the new construction, this basin will no longer be needed for that purpose and will instead be used as an informal infiltration basin for this area of hardscape. The soils in this area are sandy and allow for infiltration today. At the end of construction, the basin will be planted with grass and other plants and be maintained as a natural water quality measure for the area immediately adjacent to it. While this basin will not meet the entire stormwater quality requirements outlined in the manual, it is our hope that it does provide a measure of water quality that is satisfactory given the nature of the project and the limitations of the current usage. Please let us know if there are any questions or additional information you require to review the waiver request. Thank you for your attention to this matter. Sincerely, Nicholas Vergatos, PE APPENDIX G: STORMWATER QUANTITY WAIVER REQUEST CONSULTING ENGINEERS 9365 Counselors Row, Suite 116, Indianapolis, IN 46240 23 April 2025 City of Carmel Board of Public Works 1000 S Rangeline Rd Carmel, IN 46032 Re: Citizens Energy Group White River North Water Treatment Plant Expansion Project 11825 River Rd Carmel, IN 46033 Waiver Request from the Stormwater Quantity Requirement in the Carmel Stormwater Technical Standards Manual The above referenced project is seeking a waiver from the requirement to provide stormwater detention for the proposed construction. Given the nature of the site and its location, providing stormwater detention to meet the manual is impractical given the large number of underground utilities and critical infrastructure that exists on the site. In addition, given the nature of the property, the storm system infrastructure that exists on the site currently, only drains a portion of the River Rd right of way, a portion of the River Rd Heritage Park green space and the portion of land that the plant sits on. No other off- site water is collected or drained by the pipes. These pipes also discharge directly into the White River at the project site. Granting the waiver would not harm any adjacent or downstream properties as no downstream properties exist and the run-off for the site is being maintained. None of the run-off enters any storm system currently maintained by the City of Carmel or any other land owner. In addition, given the type of usage of the site, several of the new structures are open top basins with water inside. This results in any rainwater that falls within these basins is incorporated into the water process and not directed into any storm infrastructure. These types of basin also reduce the total impact of run-off leaving the project area as they would not contribute to the run-off. Run-off rates generated by the project can be found in the Technical Information Report for the project and summarized here: Please let us know if there are any questions or additional information you require to review the waiver request. Thank you for your attention to this matter. Sincerely, Nicholas Vergatos, PE Pervious Area Impervious Area Cn Value 2 Year Run-off 10 Year Run-off 100 Year Run-off Pre- Developed 7.00ac 0.68ac 68 7.69 cfs 11.55 cfs 16.30 cfs Post- Developed 5.22ac 1.18ac 78 9.23 cfs 13.65 cfs 19.03 cfs APPENDIX H: 1:1 COMPENSATING FLOODPLAIN CUT CALCULATION 0 40 80 FEET SCALE:1"=40' DESIGNED BY: PROJECT NO.: DATE:APRIL 2025 CONSULTANTS SEALS NO.ISSUED FORDATE BY DRAWN BY: CHECKED BY: COPYRIGHT: SHEET TITLE 1 2 3 4 5 6 A B C D E User:NVERGATOS Spec:AUS-NCSMOD File:K:\CIVIL PROJECTS\2024\24JPSC56 CEG WRN TREATMENT PLAN\DRAWINGS\C04-00 GRADING PLAN OVERALL.DWG Scale:1:1 SavedDate:4/24/2025 Time:09:16 Plot Date: Nick Vergatos; 5/1/2025; 11:14 ; Layout:AREA OF CUT 30239923 WHITE RIVER NORTH WTP EXPANSION ARCADIS U.S., INC., 2023 SHEET NO.: SCALE: ISSUE STATUS: NOT FOR CONSTRUCTION LEGAL ENTITY: ARCADIS U.S., INC. 0 1 BAR IS ONE INCH ON UNREDUCED DRAWING SHEET TITLE NBV CLM NBV AS NOTED 90% DESIGN GRADING PLAN - COMPENSATORY CUT AREA AREA OF CUT CUT/FILL CALCULATIONS ACROSS ENTIRE SITE PROPOSED FILL BELOW BFE 45787 CUYDS PROPOSED CUT BELOW BFE 46512 CUYDS TOTAL NET CUT BELOW BFE 725 CUYDS AREA OF PROPOSED CUT