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Home My WebLink About2018-05-09 Storm Water Management Plan Rcd from Kevin Hanson WWW.RAMAKER.COM STORM WATER MANAGEMENT PLAN HOLIDAY INN EXPRESS & SUITES – OAK PARK HEIGHTS, MN PREPARED FOR: MADISON HOSPITALITY GROUP RAMAKER & ASSOCIATES, INC. JOB NUMBER: 33945 HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 1 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 SITE: Memorial Avenue North Oak Park Heights, Washington County, Minnesota 55082 PREPARED FOR: Madison Hospitality Group 770 Johnson Avenue South Bloomington, Minnesota 55435 PREPARED BY: Ramaker & Associates, Inc. 855 Community Drive Sauk City, Wisconsin 53583 Telephone: (608) 643-4100 Facsimile: (608) 643-7999 RAMAKER JOB NUMBER: 33945 DATE OF REPORT ISSUANCE: May 8, 2018 James R. Skowronski, P.E. President & CEO Tomas A. Toro, P.E. Civil Engineer Katherine A Halverson Engineering Designer HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 2 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 TABLE OF CONTENTS PROJECT GENERAL INFORMATION ..................................................................................................... 3 1.1 INTRODUCTION AND PROJECT DESCRIPTION ....................................................................................... 3 1.2 PROPOSED PROJECT SCHEDULE ........................................................................................................... 3 SITE PROPERTIES AND EXISTING CONDITIONS ................................................................................. 4 2.1 SITE TOPOGRAPHY .................................................................................................................................. 4 2.2 SOIL AND GROUND COVER CONDITIONS .............................................................................................. 4 2.3 EXISTING CONDITIONS & RUNOFF TRIBUTARIES .................................................................................. 4 STORM WATER DESIGN CRITERIA ...................................................................................................... 5 3.1 REGULATIONS.......................................................................................................................................... 5 3.2 DEVELOPMENT CRITERIA ....................................................................................................................... 5 3.3 HYDROLOGIC CRITERIA ........................................................................................................................... 5 3.4 HYDRAULIC CRITERIA .............................................................................................................................. 5 SUMMARY OF RESULTS ...................................................................................................................... 7 4.1 STORM WATER QUANTITY RESULTS ......................................................................................... 7 4.2 STORM WATER QUALITY PROTECTION ................................................................................................... 7 REFERENCES ....................................................................................................................................... 8 APPENDICES LIST OF APPENDICES A. Vicinity Map B. Geotechnical Report C. Existing Conditions Watershed Map D. Proposed Conditions Watershed Map E. Calculation Results for Existing Conditions F. Calculation Results for Proposed Conditions G. RECARGA Results HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 3 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 SECTION 1 PROJECT GENERAL INFORMATION 1.1 INTRODUCTION AND PROJECT DESCRIPTION Ramaker & Associates, Inc. (Ramaker) was hired to complete Civil/Site design services for construction of a 4-story Hotel located in Oak Park Heights, Washington County, Minnesota, hereinafter referred to as “the property.” The +/- 2.4-acre property is located on the Northeast end of Memorial Avenue North. The property is currently a vacant parcel of land with grass cover and is adjacent to existing infrastructure. The proposed development will involve the construction of a 4-story, 18,000 sq. ft. building with a surface parking lot and associated drive aisles. A new storm sewer system will also be constructed and tie into the existing infiltration pond/detention basin located on the northeast corner of the site. 1.2 PROPOSED PROJECT SCHEDULE The proposed construction schedule will be as follows, but can be subject to change: · July 2018 – Construction Bidding Time · September 2018 – Beginning of Construction · September 2019 – Construction Complete / Opening of Hotel HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 4 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 SECTION 2 SITE PROPERTIES AND EXISTING CONDITIONS 2.1 SITE TOPOGRAPHY The existing topography of the property generally slopes to the east/southeast at gentle slopes towards existing infrastructure. 2.2 SOIL AND GROUND COVER CONDITIONS Soil Classification and Evaluation was completed for four soil borings advanced 26 feet below ground surface (BGS) at different locations throughout the site. In addition, one boring was advanced to 16 feet BGS in the area near the storm water infrastructure. In general, it was found that the material from existing ground surface to approximately 2 feet BGS consists of uncontrolled fill material, from 2 feet BGS to approximately 4.5 feet BGS consists of Brown Silty Clay with fine to coarse sand, and below 4.5 feet BGS consists of Brown fine to coarse SP sands. Based upon the possibility for over-excavation, the Minnesota Storm water Manual was used to determine an infiltration rate of 0.80 inches/hour for the existing storm water infiltration pond. In comparison with the existing design information provided for the existing pond, the previous calculations used an infiltration rate of 2.0 inches/hour. However, this was prior to the most recent update of infiltration rates in the Minnesota Stormwater Manual. Please refer to the attached geotechnical report for additional information, including all soil boring logs. 2.3 EXISTING CONDITIONS AND RUNOFF TRIBUTARIES This project is located on a 2.4-acre property that falls in the Brown’s Creek Watershed District’s (BCWD’s) jurisdiction. Currently the site is undeveloped and drains gently to the east/southeast. Existing slopes over the site are relatively moderate ranging mostly from 2% to 9% near the proposed hotel location and 20% to 35% in the existing detention pond. A portion of the site consists of slopes that drain to an existing infiltration/detention pond, which were included in the City of Oak Park Heights design of the pond. These areas have been included in the HydroCAD models of the existing and proposed site conditions. HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 5 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 SECTION 3 STORM WATER DESIGN CRITERIA 3.1 REGULATIONS Brown’s Creek Watershed District Rules and the City of Oak Park Heights Ordinance, Chapters 300 and 400, were used as a guideline for the design of this project. 3.2 DEVELOPMENT CRITERIA Specific development criteria for this project involved utilization of an existing infiltration pond to account for the creation of impervious area(s) from this project. BCWD Section 2.7 lists references to provide BMP Design and Construction Standards for the overall design. These references include; (a) Minnesota Pollution Control Agency, Stormwater Manual, (b) Minnesota Pollution Control Agency, Protecting Water Quality in Urban Areas Manual, and (c) Minnesota Department of Transportation, Erosion Control Handbook II. Oak Park Heights Design Guidelines require that all storm water strategies must meet the water quality standards of the Oak Park Heights Surface Water Management Plan. Consideration of minimalizing total impervious surfaces, minimalizing direct connection between impervious surfaces, and planting more vegetation are all objectives while completing the design. 3.3 HYDROLOGIC CRITERIA Areas – The total area for this project is approximately 104,500 square feet (2.4 acres). There will be approximately 72,000 square feet of new impervious area for this project. Watershed soils – The soil types for this property consist of uncontrolled fill material, Brown Silty Clay with fine to coarse sand, and Brown fine to coarse SP sands. Please refer to the attached geotechnical report for additional soil conditions and all soil boring logs. Pre/post project land use – The property is currently vacant and is zoned as Highway Business and Warehouse. Once this project is completed, the land use will continue to be Highway Business and Warehouse occupied by a new Hotel with an asphalt parking lot. Rainfall intensity & Design Frequencies – The National Oceanic and Atmospheric Administration (NOAA) precipitation frequency data server was used for determining the rainfall intensities used in this design. The frequency used was the 10-year storm event in order to check the capacity of the storm water pipes. Storm frequencies of 2, 10, and 100-year storm events were also evaluated for the capacity of the infiltration pond. The rainfall intensity was then used in the computer program HydroCAD to model the storm sewer system under certain design criteria. 3.4 HYDRAULIC CRITERIA 3.4.1 Storm Sewer Piping – The proposed storm sewer pipe on this site will mainly consist of high-density polyethylene pipes (HDPE), with one run of pipe consisting of Reinforced Concrete Pipe (RCP) as indicated on the provided construction documents. 3.4.2 Streets, Curb and Gutter – Asphaltic concrete will be utilized for the parking area and related entryways/aisles for the parking lot. The parking lot will be designed for drainage over the asphaltic concrete parking lot to drain inlets to convey water to the infiltration pond as well as portions of the asphaltic parking lot sheet flowing to a flume to convey water to the infiltration pond. HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 6 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 3.4.3 Infiltration/Detention Pond- The proposed storm system design will use an existing infiltration/detention pond to capture runoff from the proposed parking surfaces, landscaped areas and building rooftop. This pond also serves as a detention pond in order to reduce the post- development peak discharge rates, as required. 3.4.4 Floodplain and Wetlands – According to the Federal Emergency Management Agency (FEMA) map number 27163C0261E the site is Zone X which has no Base Flood Elevations determined, revised on February 3, 2010. There are no existing wetlands on or nearby the site. 3.4.5 Erosion and Sedimentation – Prior to any land disturbing activity, silt fence will be installed along the disturbance limits of the project and inlet protection will be installed and maintained on any existing and all proposed inlets until final stabilization occurs. A temporary stone tracking pad will also be installed at the southwest corner of the project off Memorial Avenue North prior to any land disturbing activity. Within 14 days of grading, any areas with exposed soil that have not been restored will have temporary hay mulch spread to reduce erosion. Permanent seeding or sod will be in place within a week of project completion and erosion matting will be used in areas of steep slopes. In addition, rip-rap will be used at all storm sewer outlet locations to help dissipate the energy and reduce the probability of erosion. HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 7 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 SECTION 4 SUMMARY OF RESULTS 4.1 STORM WATER QUANTITY RESULTS Brown’s Creek Watershed District rule 2.4.1(a) states that an applicant shall limit peak runoff flow rates for the 2-, 10- and 100-year storm events to be less than the rates during pre-development conditions. Hydrographs were developed for the 2-, 10- and 100-year, 24-hour design storms with both the pre- and post-development conditions for the project area. The calculation results from the HydroCAD model for existing and proposed site conditions are summarized below: A complete set of calculation results are provided for both Pre and Post-Developed Conditions as Appendices E and F. 4.2 STORM WATER QUALITY PROTECTION This report summarizes the City of Oak Park Heights and Brown’s Creek Watershed District rules and regulations that were undertaken as requirements for this proposed project. Coordination with staff members of the Brown’s Creek Watershed District indicated that this development project would require infiltration of storm water equal to the 2-year pre-settlement (pre-development) volume. The computer program RECARGA was used to analyze the site under pre-development and post-development scenarios to demonstrate compliance with this requirement. RECARGA information can be seen in the attached Appendix E. In order to ensure the infiltration of storm water on this site remains effective and functional, some pre- treatment devices have been included in this design. They include sump catch basin/drain inlets and rip-rap at all pipe outlets. Groundwater was observed during soil boring activities at a depth of 18.5-feet BGS, so it is anticipated the existing and proposed continued use of infiltration practice will not pose a threat to any nearby groundwater. HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 8 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 REFERENCES · City of Oak Park Heights - Ordinances · Brown’s Creek Watershed District Rules · Federal Emergency Management Agency (FEMA) - http://www.fema.gov/ · Minnesota Pollution Control Agency (MPCA) · HydroCAD computer program · Minnesota Special & Impaired Waters online database - https://www.pca.state.mn.us/water/stormwater-special-and-impaired-waters-search HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX A VICINITY MAP HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 Source: www.google.com/maps PROJECT LOCATION HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX B GEOTECHNICAL REPORT HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX C EXISTING CONDITIONS WATERSHED MAP HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX D PROPOSED CONDITIONS WATERSHED MAP HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX E CALCULATION RESULTS FOR EXISTING CONDITIONS HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX F CALCULATION RESULTS FOR PROPOSED CONDITIONS HIEx&S – OAK PARK HEIGHTS, MN - STORM WATER MANAGEMENT PLAN RAMAKER & ASSOCIATES, INC. 33945 STORM WATER MANAGEMENT PLAN_2018-05-08 APPENDIX G RECARGA RESULTS 33945 Oak Park Heights Holiday Inn & ExpressKAHEDKExisting/Required:Recarga Inputs:CN:77(As stated for Soil Group D on page 21 of the Brown Creek Watershed District Rules)Total Site:2.4acres104544sq-ftImpervious: 0%2-yr Storm Event:2.8inInfiltration Rate:0.06in/hrRecarga Stay-On Depth:1.8652inRequired Stay-On Volume:16249.62cu-ftProposed Conditions:Uncontrolled Areas:CN:30(As stated for Soil Group A on page 21 of the Brown Creek Watershed District Rules)2-yr Storm Event:2.8inInfiltration Rate:0.8in/hrWatershed:WS #12WS #13Total:Watershed Area:2717882911546sq-ft0.26506acresImpervious Area:88290378sq-ft3.27%Recarga Stay-On Depth:2.7143inUncontrolled Stay-On Volume:2611.609cu-ftInfiltration Pond Tributary Areas:Required Infiltration Stay-On Volume:(Required Stay-On Volume)-(Uncontrolled Stay-On Volume)=13638.01cu-ftCN:30(As stated for Soil Group A on page 21 of the Brown Creek Watershed District Rules)2-yr Storm Event:2.8inInfiltration Rate:0.8in/hrPond Depth:16.8in<when bottom two outlet hole/pipe are closedPond Area:3507sq-ft(at elevation 933)Watershed:WS #1WS #2WS #3WS #4WS #5WS #6WS #7WS #8WS #9WS #10WS #11Total:Watershed Area:9373542539428471192537236418514146526125991243592326sq-ft2.119513acresImpervious Area:874351673891535616189660835831414646942493070870sq-ft76.76%RecargaStay-On Depth:1.9295inat 16.8 depthInfiltration Pond Stay-On Volume:14845.25142cu-ft>13638.01cu-ftGOOD! = meets requirement^provided^req'dProject:Date: 05-07-2018Design Engineer:Reviewing Engineer: