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HomeMy WebLinkAboutDrainage Report Narrative_Summary_2019-08-123939 Priority Way South Drive, Suite 200 Indianapolis, Indiana 46240 Telephone 317 844 6777 Facsimile 317 706 6451 www.cripe.biz PIC: 180235-20000 Drainage Summary for Franciscan Orthopedic Center Of Excellence Site Clearing and Grading (Early Release Package) Carmel, Indiana Prepared for: Meridian Development Services, LLC 201 Pennsylvania Parkway, Suite 100 Indianapolis, IN 46280 August 12, 2019 Certified By: Jennifer M. Lasch, P.E., LEED, AP PE 10810099 Executive Summary The Franciscan Orthopedic Center of Excellence proposed construction project is currently in the DP/ADLS approval process under Docket Number 19060019. Due to the timing of the future occupants of the proposed hospital and Medical Office Building leaving their current facility and moving to the proposed facility, it is critical to begin site clearing, grading, and ideally foundations in the fall of 2019 to meet the current construction schedule. To meet this goal, an early release package for clearing and site grading is being proposed. The following report is a summary of the overall drainage report for this site. The Franciscan Orthopedic Center of Excellence site contains a new combined medical office building (MOB) and hospital. The MOB/Hospital is connected to a four-story parking garage structure via an above ground pedestrian connector that spans the existing gas easement that bisects the site. The proposed development is to occur on an approximately 12.12-acre parcel. In addition to the buildings, the proposed construction includes a staff paved parking area south of the MOB/hospital building, interior drives and pedestrian connectivity. An alternate 69-space paved surface parking lot located north of the garage structure is also proposed for valet parking. The project will include provision of utilities, including gas, electric, data and new connections for water and sanitary lateral services. As part of this project’s stormwater management, a series of hydrodynamic separators and underground detention is proposed for stormwater treatment prior to discharging to the INDOT ditch on the east side of the site. This Ditch is the primary stormwater outlet point for the site. For the site clearing and grading package, the vicinity of the alternate 69-space paved parking is anticipated for use as the construction staging area. There are two construction entrances proposed; one at the future north curb cut and one at the future south curb cut. Two construction access are requested to minimize the extent of construction crossing over the gas easement/pipeline. In addition, it is anticipated that the northeast underground detention area (F) and southeast underground detention area (C) will be used as sediment traps during the site clearing and grading phase. Refer to the Early Release Package Drainage Exhibit for drainage patterns and sediment trap locations. Also refer to the Early Release Package Outlet Control Structure Details for related outlet details for each sediment basin. The stormwater pollution prevention plan will be of primary importance during this initial site clearing and grading phase of construction. The site will be stabilized upon finalization of mass grading and transition into the subsequent construction phase. This page left blank intentionally DRAINAGE DESIGN REPORT FOR Franciscan Orthopedic Center of Excellence Early Release Package Site Clearing and Grading Carmel, Indiana TABLE OF CONTENTS 1.0 Introduction ......................................................................................................... 2 1.1 Project Description ................................................................................................ 2 1.2 Scope of Report .................................................................................................... 3 1.3 Existing Conditions ............................................................................................... 3 1.4 Proposed Conditions ............................................................................................. 4 2.0 Pre-Developed Drainage Analysis .................................................................... 5 2.1 Pre-Developed Site Conditions ............................................................................. 5 2.2 Allowable Release Rate Calculation ..................................................................... 6 3.0 Post-Developed Drainage Analysis .................................................................. 6 3.1 Post-Developed Conditions ................................................................................... 6 4.0 Storm Sewer Analysis ........................................................................................ 9 4.1 Storm Sewer Network ........................................................................................... 9 5.0 Water Quality Analysis ....................................................................................... 9 5.1 Post-Construction Stormwater Quality Measures .................................................. 9 6.0 Conclusion ............................................................................................................. 10 APPENDICIES Pre-developed Conditions Exhibit and Calculations Allowable Discharge Rate Calculations Exhibit Post-Developed Conditions Exhibit Storm Sewer Basins Exhibit Water Quality Basins Exhibit Early Release Package Drainage Exhibit Early Release Package Outlet Control Structure Details 2 1.0 Introduction This drainage report outlines the storm water management system to serve the Franciscan Orthopedic Center of Excellence. The proposed development is located on the Meridian Development Services, LLC parcel located north of 106th Street, west of US31, east of Illinois Street, and south of 111th Street in the City of Carmel, Hamilton County, Indiana. The purpose of this report is to identify the impacts of the stormwater runoff from the proposed development on the surrounding properties and existing storm sewer systems. The detention design for this site was governed by the Hamilton County Stormwater Ordinance. The City of Carmel Stormwater Technical Standards Manual was used for the storm sewer hydraulic calculations and the water quality design. 1.1 Project Description The Franciscan Orthopedic Center of Excellence site contains a new combined medical office building (MOB) and hospital. The MOB/Hospital is connected to a four-story parking garage structure via an above ground pedestrian connector. This connector is located above grade to provide an enclosed connection between the building structures. The connector spans the easement of the gas main that bisects the site. The proposed development is to occur on an approximately 12.12-acre parcel. There are several future elements planned for the site; a future exterior fitness and rehab area including batting cage, synthetic turf, and half basketball and tennis area and a future fitness trail/path to the east side of the site which when connected to the proposed walking areas creates an approximately 0.5-mile loop. In addition to the buildings, the proposed construction includes a staff paved parking area south of the MOB/hospital building, interior drives and pedestrian connectivity. An alternate 69-space paved surface parking lot located north of the garage structure is also proposed for valet parking. The project will include provision of utilities, including gas, electric, data and new connections for water and sanitary lateral services. As part of this project’s stormwater management, a series of hydrodynamic separators and underground detention is proposed for stormwater treatment prior to discharging to the INDOT ditch on the east side of the site. This Ditch is the primary stormwater outlet point for the site. The project involves extending the 16” water main along Illinois Street for provision of water to the site and constructing a new 10-foot wide asphalt multi- use path on the east side of the street. The path will be from the new mid-block crossing at Illinois Street north to the existing multi-use path connection. This multi-use path is part of the Bicycle and Pedestrian Thoroughfare Plan. 3 1.2 Scope of Report This report summarizes the stormwater management system for the proposed development of the Franciscan Orthopedic Center of Excellence. 1.3 Existing Conditions The existing site is predominantly vacant open field, scrub, shrub and wooded areas. Figure 1 - Existing Site The site mostly drains east to the INDOT ditch near the east property line. The ditch ultimately discharges to the Meridian Suburban Regulated Drain as part of the Williams Creek Watershed. The ditch runs southwest through the parcel south of the Franciscan Orthopedic Center of Excellence site. A portion of the 4 site drains directly south to that parcel to the same ditch flowing to the southwest. The property line is considered as the limits of the overall site watershed. The adjoining properties zoning consist of the following: North: 111th Street/Meridian Corridor Northeast: S2 (Meridian Suburban Subdivision) South: Meridian Corridor East: US 31/Meridian Corridor West: Illinois Street/S2 (Spring Mill Place) The soils maps from the US Department of Agriculture, Soil Conservation Service identifies the proposed parking as predominantly Crosby Silt loam (CrA) with some Brookston (Br). The Firm map panel number 18057C0208G dated November 19, 2014, indicate that the site lies in Flood Zone “X”. These areas are considered to be outside of the 500 year floodplain. 1.4 Proposed Conditions The proposed site consists of the new MOB/hospital and parking garage as well as surface parking, interior drives, pedestrian connectivity, and amenity spaces with a café patio space. A future fitness trail, an alternate paved parking area and an outdoor fitness training area are also envisioned for this project. Landscaping and planting buffers are incorporated into the design to complete the overall site layout. Refer to Figure 2 below. 5 Figure 2 - Proposed Conditions 2.0 Pre-Developed Drainage Analysis 2.1 Pre-Developed Site Conditions The site currently drains to the north, the east, and the south. The portion of the site that drains to the north is identified as Watershed A in the Pre-developed Conditions Exhibit. This watershed drains north to an existing 15-in regulated drain which discharges to an existing 30-in RCP that runs along the east side of the site. The existing 30-in RCP ultimately discharges to the INDOT ditch on the east side of the site. A second portion of the site is identified as Watershed B in the exhibit, and it drains directly to the INDOT ditch. Runoffs from Watersheds A and B ultimately reach the INDOT ditch. A summary of the existing release rates from each watershed is provided in the Pre-developed Conditions Exhibit. The third portion of the site directly discharges south to adjacent property. Since the INDOT ditch is considered as the primary stormwater outlet point for the development of the Franciscan Orthopedic Center of Excellence project, the focus is on the release rates of Watershed A and B which constitute the existing release rates of the site. 6 Since it is anticipated that there is going to be part of the site that will directly drain to the INDOT ditch in the post-developed conditions, it is necessary to understand the existing runoff leaving the site to effectively evaluate the post-developed conditions release rates. 2.2 Allowable Release Rate Calculation Per the City of Carmel Stormwater Technical Standards Manual the allowable release rates from the site is no greater than 0.1 cfs per acre of development for 0-10 year return interval storms and 0.3 cfs per acre of developed area for 11 - 100 year return interval storms. According to the Allowable Release Rates Calculations Exhibit the allowable release rates for Watershed A are 0.27 cfs and 0.68 cfs for the 10 and 100-year storms respectively. Watershed A discharges to the existing 30-in RCP. The Allowable release rates for Watershed B are 0.70 cfs and 2.11 cfs for the 10 and 100-year storms. Watershed B directly discharges to the INDOT Ditch on east side of the site. 3.0 Post-Developed Drainage Analysis The post-developed drainage management system for the proposed construction consists of an enclosed storm sewer network that collects most of the stormwater runoff from the site and conveys the runoff to underground detention chambers prior to discharging to the INDOT ditch. 3.1 Post-Developed Conditions As noted previously, the post-developed conditions of the site consist of a medical office building, hospital, parking garage, an alternate valet surface asphalt parking lot, small south surface parking, concrete sidewalks and a loop and interior driveways. The future outdoor fitness and rehab area and future fitness trail is included in the detention design calculations. These elements comprise of impervious area and pervious areas with curve numbers of 98 and 74, respectively. The post-developed drainage analysis is based on the topographical survey data (NAVD 88 datum) of the site. Refer to the Post-Developed Conditions Exhibit. The proposed development is divided into 4 watersheds: Watershed A, Watershed C, Watershed D and Watershed E. Each watershed discharges to its respective detention system before reaching outlet point. Refer to the table below for the characteristics of each watershed. It is worth noted that the entire site is assumed to be detained by the proposed underground detention systems. Refer to the Post- developed Conditions Exhibit. 7 Watershed Characteristics Watershed Area (ac) Curve Number Tc (min,) A 2.426 91 5 C 2.546 89 5 D 3.758 86 5 E 3.425 86 5 The overall detention system strategy is designed to detain the entire site. Two underground detentions systems are proposed for the site: System 1, composed of UGD-A, UGD-B and UGD-C, provides detention for stormwater runoffs from watersheds A and C. This underground detention system is a series of Stormtech Chambers MC-3500. The existing 30-in RCP is the outlet point for this system. System 2, composed of UGD-D, UDG-E andUGD-F, provides detention for watersheds D and E. The existing INDOT Ditch is the outlet point for this System. It is also a series of Stormtech chambers MC-3500. The runoff from the entire developed site eventually reaches the ditch on the parcel south (Indiana Farmer Mutual Insurance Company Site) that outlets through the large culvert at the southwest portion of that site. The release rates of the detention systems are based on 0.1 cfs per acre of development for 0-10 year return interval storms and 0.3 cfs per acre of developed area for 11 - 100 year return interval storms. Due to the requirement of using a minimum 6-in orifice, both detentions systems are unable to achieve the allowable release rates. A summary of the calculations is provided in the table below. Post-developed release rate Summary Table (cfs) UGD 10-year 100-year System 1 (30-in RCP outlet) A, B and C 1.26 1.92 System 2 (INDOT Ditch) D, E and F 1.39 2.05 Overall 2.65 3.97 8 Pond Staging Summary Table (ft) 10-year 100-year UGD-A 828.95 831.60 UGD-B 828.93 831.60 UGD-C 828.93 831.60 UGD-D 831.51 833.98 UGD-E 831.51 833.98 UGD-F 831.48 833.96 Both Detention systems have been sized in a way to achieve the allowable release rates if smaller orifices are allowed. In this the outlet control structure downstream of UGD-F would have a 2.5-in orifice and a 3-in orifice, and the outlet control for UGD-C would have a 4-in orifice and a 5-in orifice. Refer to following table for a summary of the release rate for this situation. Smaller orifices Post-developed release rate Summary Table (cfs) UGD 10-year 100-year System 1 (30-in RCP outlet) A, B and C 0.27 0.67 System 2 (INDOT Ditch) D, E and F 0.70 1.99 Recognizing that there are areas of direct runoff where the proposed site connects back to existing grades, it is necessary to confirm the proposed runoff as a combination of detained runoff and direct discharge do not exceed the existing conditions. A summary of the runoff generated by the direct discharge areas are included in the Direct Discharge Area Exhibit. About 3.217 acres of the pervious area directly discharges to the ditch due to grading. Below is a summary of the proposed release rates to the INDOT ditch and to the south as compared to the existing conditions. Under both scenario, the proposed release rate is less than the existing release rate. Location 10-year 100-year Rates From Detention Systems 2.65 cfs 3.97 cfs Direct discharge area 3.47 cfs 8.73 cfs Combined 6.12 cfs 12.70 cfs Existing Watershed B 10-year 100-year Existing Release Rate 7.44 cfs 18.81 cfs Drainage to the INDOT ditch is being coordinated with INDOT. Appendix C shows that this project site is 42.9% impervious. 9 4.0 Storm Sewer Analysis The storm sewer analysis for the proposed construction consists of an enclosed storm sewer network. 4.1 Storm Sewer Network Hydraflow Storm Sewers Extension for AutoCAD Civil 3D, v.8 was used to verify capacity of all proposed storm drainage pipes for the 10-year storm event peak flows. Hydraflow utilizes a graphical pipe network containing pipe data, inlet characteristics, watershed areas, and rainfall information. These flow calculations are valid for both pressure and varied flow situations including hydraulic jumps, backwater elevations, and draw down curves. These calculations are based on the rational method. Factors involved include runoff coefficient (C), time of concentration (Tc) and Area (A). Refer to the Storm Sewer Basins Exhibit. 5.0 Water Quality Analysis 5.1 Post-Construction Stormwater Quality Measures As part of the overall Stormwater Management for the site, water quality treatment is provided for the non-direct discharge stormwater runoff. A treatment train is provided via stormwater runoff being treated via a structural BMP hydrodynamic separator prior to discharging to the isolator row of the underground detention system. The isolator row is a water quality feature of the Stormtech Chamber underground detention system. There are four water quality units proposed for the site. The following is a summary of the water quality for the site: Water Quality Summary Table Location Area (ac) Structural BMP Structure No. Calculated Flow (cfs) Allowable Flow (cfs) WQ Basin A 2.117 711A 2.45 3.2 WQ Basin C 1.775 722A 2.21 3.2 WQ Basin D 2.490 753A 2.63 3.2 WQ Basin E 2.656 737A 2.53 3.2 Based on the summary Water Quality Unit AquaSwirl As-4 is proposed for all mechanical BMPs. This system complies with the design criteria presented in the City of Carmel Stormwater Technical Standards Manual and the Hamilton County Drainage Ordinance. Refer to Appendix E for Water Quality Basins Exhibit and Calculations. 10 6.0 Conclusion The proposed stormwater management plan implements a series of storm sewer networks to collect the on-site and some off-site runoff for the overall 12.2 drainage basin analyzed. The storm sewer networks direct runoff to structural BMPs and isolator rows for water quality prior to being detained in a series of underground detention prior to discharging to the INDOT ditch to the east. The following is a summary of the release rates from the site: Summary of Release Rates INDOT Ditch 10-year 100-year Existing combined 10.19 25.70 Proposed 6.12 12.70 The proposed storm drainage system complies with the criteria stated in the City of Carmel Stormwater Technical Standards Manual and the Hamilton County Drainage Ordinance for detention, water quality and storm water sewer sizing. No adverse impacts are anticipated as a result of this design. 12 14 15 16 13 11 10 TITLE:PROJECT: Date: SCALE: PROJECT NO: SHEET No. (317) 844-6777 INDIANAPOLIS, INDIANA 46240 3939 PRIORITY WAY SOUTH DRIVE, SUITE 200 www.cripe.biz REAL ESTATE SERVICES SURVEY +3D LASER SCANNING ENERGY + FACILITIES EQUIPMENT PLANNING CIVIL ENGINEERING ARCHITECTUREARCHITECTURE + INTERIORS O:\2018\180235\20000\calcs\Engr\Detention\Prelim\2nd Submittal\CAD Exhibits\Post-Developed Watershed Exhibit.dwg, August 12, 2019 5:42 AM, STEV PIERRE, © Paul I. Cripe, Inc.1 of 1 08-12-2019 180235-20000 1"=120' CARMEL, IN FRANCISCAN HEALTH FRANCISCAN ORTHOPEDIC CENTER OF EXCELLENCE CONDITIONS EXHIBIT POST-DEVELOPED 12 14 15 16 13 4445 46 11 10 9 MERIDIAN STREET (US 31)MANCHESTER COURT TOTTENHAM DRIVE16 17 26 WATERSHED B (TO INDOT DITCH) TOTAL AREA = 7.039 AC (CN = 74) FLOW RATES SUMMARY: EXISTING Q2YR = 3.24 CFS EXISTING Q10YR = 7.44 CFS EXISTING Q100YR = 18.81 CFS WATERSHED A (TO EX. 30" RCP) TOTAL AREA = 2.272 AC (CN = 74) FLOW RATES SUMMARY: EXISTING Q2YR = 1.19 CFS EXISTING Q10YR = 2.75 CFS EXISTING Q100YR = 6.89 CFS INDOT DITCHTITLE:PROJECT: Date: SCALE: PROJECT NO: SHEET No. 1 of 1 08-12-2019 180235-20000 1"=120' CARMEL, IN FRANCISCAN HEALTH FRANCISCAN ORTHOPEDIC CENTER OF EXCELLENCE CONDITIONS EXHIBIT PRE-DEVELOPED 12 14 15 16 13 4445 46 11 10 9 DIRECT DISCHARGE AREA TO INDOT DITCH TOTAL AREA = 3.217 AC (CN = 74) Q10YR = 3.47 CFS Q100YR = 8.73 CFS TITLE:PROJECT: Date: SCALE: PROJECT NO: SHEET No. 1 of 1 06-19-2019 180235-20000 1"=120' CARMEL, IN FRANCISCAN HEALTH FRANCISCAN ORTHOPEDIC CENTER OF EXCELLENCE AREA EXHIBIT DIRECT DISCHARGE 12 14 15 16 13 11 10 TITLE:PROJECT: Date: SCALE: PROJECT NO: SHEET No. (317) 844-6777 INDIANAPOLIS, INDIANA 46240 3939 PRIORITY WAY SOUTH DRIVE, SUITE 200 www.cripe.biz REAL ESTATE SERVICES SURVEY +3D LASER SCANNING ENERGY + FACILITIES EQUIPMENT PLANNING CIVIL ENGINEERING ARCHITECTUREARCHITECTURE + INTERIORS O:\2018\180235\20000\calcs\Engr\Storm\Prelim\2nd Submittal\CAD Exhibit\Storm Sewer Basins Exhibit.dwg, August 12, 2019 4:43 AM, STEV PIERRE, © Paul I. Cripe, Inc.1 of 1 08-11-19 180235-20000 1"=120' CARMEL, IN FRANCISCAN HEALTH FRANCISCAN ORTHOPEDIC CENTER OF EXCELLENCE BASINS EXHIBIT STORM SEWER 12 14 15 16 13 11 10 INDIANA FARMERS MUTUAL INSURANCE COMPANYD.B. 331, P. 109PIKE'S SPRING MILL HEIGHTSP.B. 2, PP. 93-94 16 17 26 7 TITLE:PROJECT: Date: SCALE: PROJECT NO: SHEET No. (317) 844-6777 INDIANAPOLIS, INDIANA 46240 3939 PRIORITY WAY SOUTH DRIVE, SUITE 200 www.cripe.biz REAL ESTATE SERVICES SURVEY +3D LASER SCANNING ENERGY + FACILITIES EQUIPMENT PLANNING CIVIL ENGINEERING ARCHITECTUREARCHITECTURE + INTERIORS O:\2018\180235\20000\calcs\Engr\Water Quality\Prelim\1st_Submittal\CAD Exhibit\Water Quality Basins Exhibit.dwg, June 19, 2019 10:05 AM, STEV PIERRE, © Paul I. Cripe, Inc.1 of 1 06-19-2019 180235-20000 1"=120' CARMEL, IN FRANCISCAN HEALTH FRANCISCAN ORTHOPEDIC CENTER OF EXCELLENCE BASINS EXHIBIT WATER QUALITY