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Stormwater Pollution Prevention Plan (swppp)

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In the Matter of the Application of Marshall Solar, LLC for a Site Permit for the Marshall Solar Electric Power Generating Plant in Lyon County, Minnesota MPUC Docket No. IP-6941/GS-14-1052 Updated Site Plan Drawings and Specifications and SWPPP (Site Permit Sections 4.2.7 and 8.3) STORMWATER POLLUTION PREVENTION PLAN (SWPPP) FOR MARSHALL SOLAR (Part 1 OF 2) Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Stormwater Pollution Prevention Plan (SWPPP) For Construction Activities At: Marshall Solar, LLC 3163 290th St Marshall, MN 56258 (320) 356-7351 SWPPP Prepared For: NextEra Energy Resources, LLC Travis Baukol 700 Universe Boulevard Juno Beach, FL 33408 320-226-2097 [email protected] SWPPP Prepared By: EVS, Inc. Dan Bowar, PE 10025 Valley View Road, Suite 140 Eden Praire, Minnesota 55344 Phone: 952-646-0236 Fax: 952-646-0290 SWPPP Preparation Date: 04/11/2016 Estimated Project Dates: Project Start Date: May 2016 Project Completion Date: December 2016 i Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Contents SECTION 1: CONTACT INFORMATION/RESPONSIBLE PARTIES ................................................................ 1 1.1 Operator(s) / Subcontractor(s) ................................................................................................... 2 1.2 Stormwater Team .......................................................................................................................... 2 SECTION 2: SITE EVALUATION, ASSESSMENT, AND PLANNING ............................................................... 3 2.1 Project/Site Information ............................................................................................................... 3 2.2 Discharge Information.................................................................................................................. 3 2.3 Nature of the Construction Activity ........................................................................................... 5 2.4 Sequence and Estimated Dates of Construction Activities ................................................... 5 2.5 Allowable Non-Stormwater Discharges .................................................................................... 6 2.6 Site Maps ........................................................................................................................................ 6 SECTION 3: DOCUMENTATION OF COMPLIANCE WITH OTHER FEDERAL REQUIREMENTS ..................... 6 3.1 Endangered Species Protection ................................................................................................ 7 3.2 Historic Preservation...................................................................................................................... 8 3.3 Safe Drinking Water Act Underground Injection Control Requirements .............................. 8 SECTION 4: EROSION AND SEDIMENT CONTROLS ................................................................................... 9 4.1 Natural Buffers or Equivalent Sediment Controls ..................................................................... 9 4.2 Perimeter Controls ........................................................................................................................ 9 4.3 Sediment Track-Out ...................................................................................................................... 9 4.4 Stockpiled Sediment or Soil ....................................................................................................... 10 4.5 Minimize Dust ............................................................................................................................... 10 4.6 Minimize the Disturbance of Steep Slopes .............................................................................. 11 4.7 Topsoil ........................................................................................................................................... 11 4.8 Soil Compaction ......................................................................................................................... 12 4.9 Storm Drain Inlets ......................................................................................................................... 12 4.10 Constructed Stormwater Conveyance Channels................................................................. 12 4.11 Sediment Basins ........................................................................................................................... 13 4.12 Chemical Treatment .................................................................................................................. 14 4.13 Dewatering Practices ................................................................................................................. 14 4.14 Other Stormwater Controls ........................................................................................................ 14 4.15 Site Stabilization ........................................................................................................................... 14 SECTION 5: POLLUTION PREVENTION STANDARDS ................................................................................ 16 5.1 Potential Sources of Pollution .................................................................................................... 16 5.2 Spill Prevention and Response .................................................................................................. 17 5.3 Fueling and Maintenance of Equipment or Vehicles ........................................................... 17 5.4 Washing of Equipment and Vehicles ...................................................................................... 18 5.5 Storage, Handling, and Disposal of Construction Products, Materials, and Wastes ........ 18 5.6 Washing of Applicators and Containers used for Paint, Concrete or Other Materials ... 19 5.7 Fertilizers ........................................................................................................................................ 20 5.8 Other Pollution Prevention Practices ....................................................................................... 20 SECTION 6: INSPECTION AND CORRECTIVE ACTION ............................................................................ 21 6.1 Inspection Personnel and Procedures ..................................................................................... 21 6.2 Log of Changes to the SWPPP .................................................................................................. 23 6.3 Delegation of Authority ............................................................................................................. 23 SECTION 7: TRAINING ............................................................................................................................. 24 SECTION 8: CERTIFICATION AND NOTIFICATION .................................................................................. 25 SWPPP APPENDICES ................................................................................................................................ 26 ii Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SWPPP APPENDICES Appendix A – Exhibits A1. Site Maps A2. Project Stormwater Management Plan A3. Project Plan Sheets Appendix B – Copy of General NPDES Permit Appendix C – NOI and EPA Authorization Email Appendix D – Inspection Form Appendix E – SWPPP Amendment Log Appendix F – Subcontractor Certifications/Agreements Appendix G – Grading and Stabilization Activities Log Appendix H – Training Log Appendix I – Delegation of Authority Appendix J – Notice of Termination (NOT) 1 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 1: CONTACT INFORMATION/RESPONSIBLE PARTIES 1.1 Operator(s) / Subcontractor(s) Operator(s): Blattner Energy, Inc. Jordan Peterson 392 County Road 50 Avon, MN 56310 (320) 356-7351 Subcontractor(s): Insert Company or Organization Name: Insert Name: Insert Address: Insert City, State, Zip Code: Insert Telephone Number: Insert Fax/Email: Insert area of control (if more than one operator at site): Emergency 24-Hour Contact: Blattner Energy, Inc. Jordan Peterson (320) 356-7351 1.2 Stormwater Team Design Civil Engineer Noah Waterhouse 952-646-0246 [email protected] Design Civil Engineer Dan Bowar 952-646-0236 [email protected] Erik Sweeney Contractors Civil Engineer (320) 356-7351 2 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 2: SITE EVALUATION, ASSESSMENT, AND PLANNING 2.1 Project/Site Information Project Name and Address Project/Site Name: Marshall Solar Project Street/Location: 3163 290th St City: Marshall State: MN ZIP Code: 56258 County or Similar Subdivision: Lyon County Project Latitude/Longitude Latitude: 44.4750 º N (decimal) Longitude: -95.6650 º W (decimal) Method for determining latitude/longitude: USGS topographic map (specify scale: Other (please specify): http://www.latlong.net Horizontal Reference Datum: NAD 27 NAD 83 or WGS 84 ) EPA Web site GPS Unknown If you used a U.S.G.S topographic map, what was the scale? ____________________________ Additional Project Information Is the project/site located on Indian country lands, or located on a property of religious or cultural significance to an Indian tribe? Yes No Are you applying for permit coverage as a “federal operator” as defined in Appendix A of the 2012 CGP? Yes No 2.2 Discharge Information Does your project/site discharge stormwater into a Municipal Separate Storm Sewer System (MS4)? Yes No Are there any surface waters that are located within 50 feet of your construction disturbances? Yes No 3 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Table 1 – Names of Receiving Waters Name(s) of the first surface water that receives stormwater directly from your site and/or from the MS4 (note: multiple rows provided where your site has more than one point of discharge that flows to different surface waters) 1. Un-named County Ditch (North end of Property) 2. Un-named County Ditch (South end of Property) Table 2 – Impaired Waters / TMDLs (Answer the following for each surface water listed in Table 1 above) Is this surface water listed as “impaired”? 1. 2. YES YES What pollutant(s) are causing the impairment? NO NO If you answered yes, then answer the following: Has a TMDL been Title of the TMDL document completed? YES YES Pollutant(s) for which there is a TMDL NO NO The topographic survey of the existing site was analyzed to determine stormwater discharge patterns off the site. From there, USGS topographic maps along with the MPCA Stormwater Mapping Tool were used to determine the remaining flow paths that the stormwater would take to reach the above waters. See Appendix A. Table 3 – Tier 2, 2.5, or 3 Waters (Answer the following for each surface water listed in Table 1 above) 1. 2. Is this surface water designated as a Tier 2, Tier 2.5, or Tier 3 water? (see Appendix F) YES NO YES NO If you answered yes, specify which Tier (2, 2.5, or 3) the surface water is designated as? 4 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR 2.3 Nature of the Construction Activity General Description of Project The construction project is a proposed photovoltaic electricity generation solar facility. It will include solar panels mounted on steel piles, inverter stations and access roads throughout the site. The site will also include a security fence along the site perimeter. Size of Construction Project The property is 438.72 acres. The total disturbed area is expected to be 71.19 acres The maximum area to be disturbed at one time is 71.19 acres 2.4 Sequence and Estimated Dates of Construction Activities Phase I Initial Erosion Control Project will begin with installation of perimeter control including silt fence and rock construction entrance. This phase of work will begin in May 2016 and be complete in May 2016. Initial erosion control devices will be left in place until final stabilization happens in December of 2016. Phase II Site Grading Once initial erosion control is in place, topsoil will be stripped in areas that require grading. Topsoil will be pushed outside of the cut/fill areas and collected into designated spots for later use. Topsoil stockpiles will be protected through BMP’s described in later sections of this document. Once topsoil is removed from the cut/fill areas, the sub-grade materials will be removed as required from on-site hills to on-site low spots. The sub-grade materials will be compacted in place. When compaction is complete, the topsoil stockpiles will be re-spread over the conditioned sub-grade areas. This newly spread topsoil will be loosely compacted and/or “tracked” and employ BMP’s. This phase includes the construction of onsite gravel roads. This work would start with the stripping of topsoil materials from the 20-foot wide roadbeds to a depth to be determined by an onsite soil scientist with input from an agricultural monitor, or at least 6 inches. Topsoil will be windrowed to the edges of each roadbed. Windrowing will consist of pushing materials into rows of spoil piles adjacent to the road which will be loosely compacted and/or “tracked” and protected by BMP’s. The sub-grade will then be compacted. The previously windrowed topsoil material will then be re-spread around the new gravel material along the road shoulders. This phase of work will begin in May 2016 and be complete in the summer of 2016. The rolled erosion control product installed during this phase will be permanent. Phase III Solar Construction 5 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR After completion of the site work, construction of the solar features will begin with pile driving. Piles will be directly driven with no excavation required. Trenching for underground electrical will commence at the completion of pile driving. Any stabilized ground that is disturbed by trenching process will be immediately restabilized. Seventeen concrete equipment pads will be constructed to support the inverters and transformers. Racking and solar modules will be installed on the steel piles This phase of work will begin in the Summer of 2016 and will be completed by December of 2016. 2.5 Allowable Non-Stormwater Discharges List of Allowable Non-Stormwater Discharges Present at the Site Type of Allowable Non-Stormwater Discharge Discharges from emergency fire-fighting activities Fire hydrant flushings Landscape irrigation Waters used to wash vehicles and equipment Water used to control dust Potable water including uncontaminated water line flushings Routine external building wash down Pavement wash waters Uncontaminated air conditioning or compressor condensate Uncontaminated, non-turbid discharges of ground water or spring water Foundation or footing drains Construction dewatering water 2.6 Likely to be Present at Your Site? YES YES YES NO NO NO YES YES YES YES YES YES NO NO NO NO NO NO YES YES YES NO NO NO Site Maps See Appendix A. 2.7 Stormwater Design Approach and Calculations See Appendix A. 6 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 3: DOCUMENTATION OF COMPLIANCE WITH OTHER FEDERAL REQUIREMENTS 3.1 Endangered Species Protection Eligibility Criterion Under which criterion listed in Appendix D of General Permit are you eligible for coverage under this permit? A B C D E It has been determined that no federally-listed threatened or endangered species or their designated critical habitats will be affected by construction activity or discharge and dischargerelated activity. The U.S. Fish and Wildlife Service website was used for reference. http://www.fws.gov/midwest/endangered/lists/minnesot-cty.html The county distribution list PDF found on the above website lists the Northern long-eared bat and Dakota Skipper as threatened species for Lyon County. Also, the Poweshiek skipperling is listed as an endangered species in Lyon County. Maps of critical habitats of the Dakota skipper and Poweshiek skipperling are provided on the above website. In both cases, the critical habitat does not include any portion of our site or discharge area. Neither species is affected by the proposed construction. The United States Fish and Wildlife Service Final 4(d) Rule for conserving the northern long-eared bat states the following: “Under this final rule, within the WNS zone, incidental take is prohibited only if: (1) Actions result in the incidental take of northern long-eared bats in hibernacula; (2) actions result in the incidental take of norther long-eared bats by altering a known hibernaculum’s entrance or interior environment if the alteration impairs an essential behavioral pattern, including sheltering northern long-eared bats; or (3) tree-removal activities result in the incidental take of northern long-eared bats when the activity either occurs within 0.25 mile of a known hibernaculum, or cuts or destroys known occupied maternity roost trees, or any other trees within a 150-foot radius from the maternity roost tree, during the pup season (June 1 through July 31.)” This project does occur within the WNS Zone as determined by the USFWS. However, According to the April 1, 2016 “Townships Containing Northern Long-Eared Bat (NLEB) Maternity Roost Trees and/or Hibernacula Entrances in Minnesota” (DNR/USFWS 2016) publication, there are no known maternity roost trees and/or hibernacula entrances. Therefore, all sections of the above rule do not apply to this project. See Appendix A.1 for maps pertaining to applicability of Long Eared Bat habitat. 7 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR 3.2 Historic Preservation An Environmental Assessment (EA) was conducted for the proposed project site. As part of the assessment, the Minnesota State Historic Preservation Office (SHPO) concluded that there are no properties listed in the national or state register of historic places and no known or suspected archaeological properties in the project area. The EA document was used for reference and is publicly available at the following website: http://www.marshallsolarproject.com/resources.html 3.3 Safe Drinking Water Act Underground Injection Control Requirements Do you plan to install any of the following controls? Check all that apply below. Infiltration trenches (if stormwater is directed to any bored, drilled, driven shaft or dug hole that is deeper than its widest surface dimension, or has a subsurface fluid distribution system) Commercially manufactured pre-cast or pre-built proprietary subsurface detention vaults, chambers, or other devices designed to capture and infiltrate stormwater flow Drywells, seepage pits, or improved sinkholes (if stormwater is directed to any bored, drilled, driven shaft or dug hole that is deeper than its widest surface dimension, or has a subsurface fluid distribution system) None of the above controls apply to this project. 8 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 4: EROSION AND SEDIMENT CONTROLS 4.1 Natural Buffers or Equivalent Sediment Controls Buffer Compliance Alternatives Are there any surface waters within 50 feet of your project’s earth disturbances? 4.2 YES NO Perimeter Controls General Silt fence and fiber rolls will be installed as perimeter sediment control. Specific Perimeter Controls Perimeter Control # 1 Perimeter Control Description Silt fence will be installed around the perimeter of the site. See Appendix A for silt fence specifications. Installation May 2016, will be installed prior to any earth disturbing activities. Maintenance Requirements Sediment will be removed from silt fence when it reaches one-half the height of the fence from the ground. Will be inspected weekly and after rain events and repaired if necessary. Perimeter Control # 2 Perimeter Control Description Fiber rolls will be used to compliment silt fence in areas where large disturbed areas are anticipated to occur. See Appendix A for fiber roll specifications. Installation Immediately following grading of large disturbed areas. Maintenance Requirements Fiber rolls will be inspected weekly and after each rain event and repaired if necessary. 4.3 Sediment Track-Out General A rock construction entrance will be used to minimize sediment track-out. Specific Track-Out Controls Track-Out Control # 1 Track-Out Control Description 9 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR A gravel pad will be installed at the entrance of the site. See Appendix A for rock construction entrance specifications. Installation May 2016, will be installed prior to any earth disturbing activities. Maintenance Requirements Gravel will be added periodically to the construction entrance to ensure entrance stability and effectiveness. Sediment tracked offsite will be swept up immediately. 4.4 Stockpiled Sediment or Soil General Soil stockpiles are anticipated to occur periodically throughout construction on the project. As grading commences, soil will be temporarily stripped and stockpiled in localized areas. Soils in areas of cut/fill may be temporarily stockpiled before being moved from high spots to low spots. Stockpiles will be located away from surface waters and buffers and silt fence will be installed at the toe of the piles. See Section 4.7 for specific controls used for topsoil. Specific Stockpile Controls Stockpile Control # 1 Stockpiled Sediment/Soil Control Description Silt fence will be temporarily installed around stockpiles to prevent sediment discharge to the site. Stockpiles will also be placed in areas that reduce the chance of erosion as best can be done. See appendix A for silt fence specifications. Installation As needed to complete grading. Maintenance Requirements Soil will not be hosed down on impervious surfaces. Silt fence will be inspected weekly and after storm events and repaired if necessary. 4.5 Minimize Dust General Sprinkling will be used to minimize dust on the site. Specific Dust Controls Dust Control # 1 Dust Control Description Sprinkling will be used on haul roads, high traffic areas and earth disturbance on the site to minimize dust. Approved sprinkling truck will be used. Installation As-needed until site is permanently stabilized. 10 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Maintenance Requirements Dust will be monitored throughout construction and sprinkling will be used as-needed to minimize dust. 4.6 Minimize the Disturbance of Steep Slopes General The topography of the site is relatively flat with slopes typically ranging from 1-5%. Small portions of the site have slopes exceeding 5%. Grading of steep slopes will be minimized to areas where solar arrays are anticipated. These areas will be graded to slopes no greater than 5%. The disturbance of any other areas with steep slopes will be minimized by limiting unnecessary vehicle or equipment traffic. Specific Steep Slope Controls Steep Slope Control # 1 Steep Slope Control Description Silt fence and fiber rolls will be used to minimize sediment discharge from areas where steep slopes are disturbed. See Appendix A for silt fence and fiber roll specifications. Installation Silt fence will be installed prior to any earth disturbing activities. Fiber rolls will be installed immediately after steep slopes have been graded. Maintenance Requirements Sediment will be removed from silt fence when it reaches one-half the height of the fence from the ground. Silt fence and fiber rolls will be inspected weekly and after each rain event and repaired if necessary. 4.7 Topsoil General Topsoil will be stripped and stockpiled periodically throughout construction on the project. Topsoil will first be stripped in areas that require grading. Topsoil will be pushed outside of the cut/fill areas and collected into designated spots for later use. Topsoil stockpiles will be located away from surface waters and silt fence will be installed at the toe of the piles. Once grading has been completed, the topsoil piles will be re-spread. This newly spread topsoil will be loosely compacted and/or “tracked”. Perimeter BMP’s will prevent any sediment from topsoil from leaving the site. For road construction, topsoil will be stripped from the 20-foot wide roadbeds and adjacent ditches (if necessary). Topsoil will be windrowed to the edges of each roadbed. Windrowing will consist of pushing materials into rows of spoil piles adjacent to the road which will be loosely compacted and/or tracked. Once roads are constructed, the previously windrowed topsoil will be re-spread around the new gravel material along the road shoulders. The agricultural land of this project area has been classified as prime farmland. In order to ensure that appropriate measures are taken to preserve topsoil, an agricultural monitor will be assigned to this project to make inspections, monitor for soil compaction, make recommendations to the construction manager, etc. 11 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR The depth of the topsoil to be stripped at any location will be determined by a qualified soil scientist that will be onsite during construction to test the depth and quality of the topsoil. The test data and topsoil strip depth recommendation will be provided to the agricultural monitor for review and input. Specific Topsoil Controls Topsoil Control # 1 Topsoil Control Description Silt fence will be installed at the toe of the stockpiles to preserve segregation from other soils. Installation As-needed until final grading is completed. Maintenance Requirements Silt fence will be inspected weekly and after storm events and repaired if necessary. 4.8 Soil Compaction General Soil compaction is required for support of structural elements, i.e. roads, concrete pads, etc. Outside of structural areas, compaction will be limited by minimizing unnecessary vehicle or equipment traffic. The agricultural monitor will assist with making sure that non-structural soils are not excessively compacted by construction traffic. There are no infiltration BMPs that require specific protection against soil compaction. 4.9 Storm Drain Inlets General There are several drain tile inlets on the project site that will require protection from sediment discharge. Specific Storm Drain Inlet Controls Storm Drain Inlet Control # 1 Storm Drain Inlet Control Description Fiber logs will be used as inlet protection. See Appendix A for fiber log specifications. Installation May 2016, will be installed prior to any earth disturbing activity. Maintenance Requirements Fiber logs will be cleaned, or removed and replaced, as sediment accumulates, the filter becomes clogged, and/or performance is compromised. Where there is evidence of sediment accumulation adjacent to the fiber roll, deposited sediment will be removed by the end of the same work day in which it is found or by the end of the following work day if removal by the same work day is not feasible. 12 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR 4.10 Constructed Stormwater Conveyance Channels General No channels are needed for stormwater conveyance. 4.11 Sediment Basins General There are two subcatchments on the site that have a disturbed area greater than ten acres. However, only one of them drains more than ten disturbed acres to a common location. That area is located centrally in the south half of our project. A permanent stormwater basin that is already designed to store runoff for this subcatchment will be used as a sediment basin until final stabilization. It will then be returned back to function as a permanent stormwater feature. The north portion of the site has a disturbed area greater than 10 acres but it does not drain to a common location. A majority of the subcatchment exhibits sheet flow. An additional permanent stormwater basin that is already designed to store runoff for the subcatchment will be used as a sediment basin until final stabilization. This basin will be utilized even though we have determined that it is not required by the MPCA General Permit. The remainder of the subcatchments have disturbed areas less than 10 acres and do not require temporary sediment basins. Sediment generated in those subcatchments less than 10 acres will be treated by other BMP’s such as silt fence, erosion control blanket, fiber logs, etc. Specific Sediment Basin Controls Sediment Basin Control # 1 Sediment Basin Control Description The temporary sediment basin located in the south portion of the project site will accept runoff from 21.87 acres of disturbed area. Using the criteria of 3600 cf per acre drained, the required volume of the basin is 78,732 cf. The volume of the basin will be 296,797 cf which is the size of the permanent stormwater basin that the sediment basin will later be converted to. This will provide ample storage volume for sediment. There is an existing drain tile inlet located inside the basin which will allow the basin to draw-down. Sediment Basin Control # 2 The temporary sediment basin located in the north portion of the project site will have a volume of 12,018 cf. This basin does not have a minimum volume requirement since the disturbed area in this subcatchment does not drain to a common location. The basin will be used along with silt fence as additional sediment control for the subcatchment, although it is not required. Installation The temporary sediment basins will be installed at the same time as the perimeter sediment controls in May of 2016. The sediment basins will be converted to permanent stormwater basins in the Fall of 2016 after final stabilization of the tributary drainage area. 13 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Maintenance Requirements Maintenance for the sediment basins will include removal of accumulated sediment when it has reached ½ of the design volume. Other maintenance will include adequate protection of the drain tile inlet inside the sediment basin to allow it to maintain its draw-down capabilities. The inlet protection device will be cleaned out when sediment has reached ½ the height of the device and fixed if damaged. 4.12 Chemical Treatment Treatment chemicals will not be used on this site. 4.13 Dewatering Practices General Dewatering is not expected to occur on this site. 4.14 Other Stormwater Controls None 4.15 Site Stabilization Site Stabilization Practice Vegetative Non-Vegetative Temporary Permanent Description of Practice Stockpiles and disturbed areas will be temporarily stabilized. Any stockpiles that occur or any ground that is has not been permanently graded but work has temporarily ceased shall be temporarily stabilized by seeding, erosion control blankets or another qualified stabilization method. They must be stabilized within 7 days of work ceasing. An acceptable method of stabilization will be chosen by the contractor. See Appendix A for erosion control specifications. Maintenance Requirements • Temporary stabilization methods will be inspected weekly and after rainfall events and repaired if necessary. Site Stabilization Practice Vegetative Non-Vegetative Temporary Permanent Description of Practice The site will be permanently stabilized by planting a mixture of native prairie grasses and forbs. The entire site, with the exception of gravel roads and electrical equipment pads, will be planted uniformly. The land use will be converted from annually rotated crop land to permanently 14 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR vegetated grass cover. Site will be considered stabilized once it has reached 70% density of its expected final growth. The entire site will be flattened to slopes no larger than 5% and water will be allowed to sheet flow across the permanent vegetation in a manner that mimics existing flow paths. An applicable seed mix that meets these requirements has been chosen based on recommendations from local soil scientists and the MN DNR. Prairie grasses and wildflowers local to Lyon County will be selected. The prairie grass will not shade or interfere with panel operations and maintenance. Also, a mix of plant species with varying sun tolerances will be selected due to some areas of the project receiving less sun than others. Grading for construction will begin in May 2016 and initial seeding will occur as grading is completed, likely in late May or early June 2016. As grading is completed, all existing weeds will be removed and the area prepared for initial seeding. The initial seeding will be primarily to control erosion during the remainder of construction. This seeding would consist of a crop cover of oats at a density of 20 pounds per acre that will temporarily stabilize the soil while solar panels are being installed and until the native prairie species can fully establish. The seeding of the prairie species would follow once construction is complete in December. An “Agricultural Mitigation Plan” has been developed for this project and should be consulted for further detail on seed specifications, planting and maintenance. Installation Disturbed areas will be initially seeded immediately and soils will be protected no more than 7 days after earth disturbing activities occur. Maintenance Requirements • Permanent vegetation will be inspected once per month to ensure uniform seeding and growth and re-seeded if necessary. Final Stabilization: The site will be permanently stabilized by the methods described above. In order to achieve Final Stabilization, the following must occur: All soil disturbing activities at the site have been completed and all soils are stabilized by a uniform perennial vegetative cover with a density of 70% of its expected final growth The permanent stormwater management system is constructed, meets all requirements and is operating. Sediment basins must be removed, graded to final elevation, and stabilized. All temporary synthetic and structural BMPs must be removed Notice of Termination (NOT) must be submitted to the MPCA in accordance with the NPDES General Permit 15 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 5: POLLUTION PREVENTION STANDARDS 5.1 Potential Sources of Pollution Construction Site Pollutants Pollutant-Generating Activity Pollutants or Pollutant Constituents (that could be discharged if exposed to stormwater) Concrete Washout Concrete Lubricants Oil based solvents Fuel Oil based solvents Cleaners Oil based solvents Location on Site (or reference SWPPP site map where this is shown) Near site entrance Used in construction equipment, stored in contained construction trailer Used in construction equipment, stored in contained construction trailer Used in construction equipment maintenance, stored in contained construction trailer 16 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR 5.2 Spill Prevention and Response 5.3 Fueling and Maintenance of Equipment or Vehicles General Spill kits will be made readily available to eliminate the discharge of spilled or leaked chemicals. All employees that are to fuel equipment and handle fuel shall be trained in the proper procedures for the safe handling and storage of fuels. Employees will also be trained in the proper execution of the spill kit in the event of a spill. Specific Pollution Prevention Practices Pollution Prevention Practice # 1 Description Spills will be cleaned up immediately, using dry clean-up methods where possible, and materials will be disposed of in accordance with federal, state, or local requirements. Spills will not be cleaned by hosing down the area. The source of the spill will be eliminated to prevent discharge. Installation Available through life of construction activity. 17 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Maintenance Requirements Spills will be cleaned up immediately and equipment and storage containers will be inspected regularly to identify leaks or signs of deterioration. 5.4 Washing of Equipment and Vehicles General Vehicles will be washed in designated areas where wash water will be directed to a sediment basin. Soap and solvents will not be used for vehicle washing at construction site. Installation As-needed throughout construction. Maintenance Requirements Sediment from wash water will be disposed of properly. 5.5 Storage, Handling, and Disposal of Construction Products, Materials, and Wastes 5.5.1 Building Products, Pesticides, Herbicides, Insecticides, Fertilizers, Landscape Materials, Diesel Fuel, Oil, Hydraulic Fluids, Other Petroleum Products, Other Chemicals and Hazardous or Toxic Waste Materials and/or contaminants should be stored in a manner that minimizes the potential to discharge into storm drains or watercourses. An on-site area should be designated for material delivery and storage. All materials kept on site should be stored in their original containers with legible labels, and if possible, under a roof or other enclosure. Labels should be replaced if damaged or difficult to read. Bermed-off storage areas are an acceptable control measure to prevent contamination of storm water. MSDS should be available for referencing clean-up procedures. Any release of chemicals/contaminants should be immediately cleaned up and disposed of properly. Contractors should immediately report all spills to the Primary Contact, who should notify the appropriate agencies, if needed. To reduce the risks associated with hazardous materials on site, hazardous products should be kept in original containers unless they are not re-sealable. The original labels and MSDS should be retained on site at all times. Hazardous materials and all other material on site should be stored in accordance with manufacturer or MSDS specifications. When disposing of hazardous materials, follow manufacturer or Local and State recommended methods. The following good housekeeping practices should be followed on site during the construction project: An effort should be made to store only enough products required to do the job. All materials stored on site should be stored in a neat, orderly manner in their appropriate containers and adequately protected from the environment. Products should be kept in their original containers with the original manufacturer's label. Substances should not be mixed with one another unless recommended by the manufacturer. Operations should be observed as necessary to ensure proper use and disposal of materials on site. Whenever possible, all of a product should be used up before disposing of the container. Manufacturer's recommendations for proper use and disposal should be followed. 18 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR 5.5.2 Construction and Domestic Waste General Dumpsters will be provided to contain construction and domestic waste. Demolition and construction waste will be disposed of off-site. Specific Pollution Prevention Practices Pollution Prevention Practice # 1 Description Waste will be cleaned up and disposed of into designated dumpster at the end of each work day. Installation Available throughout construction activity. Maintenance Requirements Dumpster will be emptied when full by an approved waste disposal company. Waste will not be allowed to overflow. 5.5.3 Sanitary Waste General Portable toilets will be provided Specific Pollution Prevention Practices Pollution Prevention Practice # 1 Description Toilets will be positioned so that they are secure and will not be tipped or knocked over. Installation Available throughout construction activity. Maintenance Requirements Waste will be disposed of by approved disposal company. 5.6 Washing of Applicators and Containers used for Paint, Concrete or Other Materials General Concrete washout area will be designated. Specific Pollution Prevention Practices Pollution Prevention Practice # 1 Description Concrete washout area will be designated in centralized and accessible location. Concrete wash water will be directed to a leak-proof pit. See Appendix A for concrete washout drawings and specifications. 19 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Installation Prior to any concrete placing activity on the site. Maintenance Requirements Waste will be emptied and disposed of properly when the wash out is at capacity. 5.7 Fertilizers General • Fertilizers will not be used in any capacity for this project. 5.8 Other Pollution Prevention Practices General No other pollution prevention practices apply to this site. 20 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 6: INSPECTION AND CORRECTIVE ACTION 6.1 Inspection Personnel and Procedures Personnel Responsible for Inspections The onsite superintendent employed by Blattner Energy will be responsible for conducting site inspections in compliance with the Minnesota NPDES Permit. If superintendent is not onsite, other qualified personnel shall inspect. Inspection Schedule and Procedures The construction site will routinely be inspected at least once every seven days during active construction and within 24 hours after a rainfall event greater than 0.5 inches in 24 hours. Following an inspection that occurs within 24 hours after a rainfall event, the next inspection must be conducted within seven days after the rainfall event. All inspections and maintenance conducted during construction must be recorded within 24 hours in writing and these records must be retained with the SWPPP. Records of each inspection and maintenance activity shall include: a) Date and time of inspections. b) Name of person(s) conducting inspections. c) Findings of inspections, including the specific location where corrective actions are needed d) Corrective actions taken (including dates, times, and party completing maintenance activities) e) Date and amount of all rainfall events greater than 0.5 inches in 24 hours. Rainfall amounts must be obtained by properly maintained rain gauge installed onsite, a weather station that is within 1 mile of your location or a weather reporting system that provides site specific rainfall data from radar summaries. f) If any discharge is observed to be occurring during the inspection, a record of all points of the property from which there is a discharge must be made, and the discharge should be described (i.e., color, odor, floating, settled, or suspended solids, foam, oil sheen, and other obvious indicators of pollutants) and photographed. g) Any amendments to the SWPPP proposed as a result of the inspection must be documented Reductions in Inspection Frequency a) Where parts of the project site have permanent cover, but work remains on other parts of the site, inspections of the areas with permanent cover may be reduced to once per month. b) Where construction sites have permanent cover on all exposed soil areas and no construction activity is occurring anywhere on the site, the site must be inspected during non-frozen ground conditions at least once per month for a period of 12 months. Following the twelfth month of permanent cover and no construction activity, inspections may be terminated until construction activity is once again initiated unless the permittee(s) is/are notified in writing by the MPCA that erosion issues have been detected at the site and inspections need to resume. 21 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR c) Where work has been suspended due to frozen ground conditions, the inspections may be suspended. The required inspections and maintenance schedule must begin within 24 hours after runoff occurs at the site or 24 hours prior to resuming construction, whichever comes first. The permittee is responsible for the inspection and maintenance of temporary and permanent water quality management BMPs, as well as all erosion prevention and sediment control BMPs, until the project has undergone final stabilization, and an NOT has been submitted to the MPCA. The permittee must inspect all erosion prevention and sediment control BMPs and Pollution Prevention Management Measures to ensure integrity and effectiveness during all routine and post-rainfall event inspections. All nonfunctional BMPs must be repaired, replaced, or supplemented with functional BMPs by the end of the next business day after discovery, or as soon as field conditions allow access unless another time frame is specified below. The permittee must investigate and comply with the following inspection and maintenance requirements: a) All perimeter control devices must be repaired, replaced, or supplemented when they become nonfunctional or the sediment reaches one-half the height of the device. These repairs must be made by the end of the next business day after discovery, or thereafter as soon as field conditions allow access. b) Temporary and permanent sedimentation basins must be drained and the sediment removed when the depth of sediment collected in the basin reaches one-half the storage volume. Drainage and removal must be completed within 72 hours of discovery, or as soon as field conditions allow access. c) Surface waters, including drainage ditches and conveyance systems, must be inspected for evidence of erosion and sediment deposition during each inspection. The permittee must remove all deltas and sediment deposited is surface waters, including drainage ways, catch basins, and other drainage systems, and restabilize the areas where sediment removal results in exposed soil. The removal and stabilization must take place within seven days of discovery unless precluded by legal, regulatory, or physical access constraints. The permittee shall use all reasonable efforts to obtain access. If precluded, removal and stabilization must take place within seven calendar days of obtaining access. The permittee is responsible for contacting all local, regional, state, and federal authorities and receiving any applicable permits, prior to conducting any work in surface waters. d) Construction site vehicle exit locations must be inspected for evidence of off-site sediment tracking onto paved surfaces. Tracked sediment must be removed from all paved surfaces both on and off site within 24 hours of discovery, or if applicable, within a shorter time. e) Streets and other areas adjacent to the project must be inspected for evidence of off-site accumulations of sediment. If sediment is present, it must be removed in a manner and at a frequency sufficient to minimize off-site impacts. All infiltration areas must be inspected to ensure that no sediment from ongoing construction activity is reaching the infiltration area. All infiltration areas must be inspected to ensure that equipment is not being driven across the infiltration area. Inspection Report Forms See appendix D 22 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR 6.2 Log of Changes to the SWPPP An amendment log form is included within this SWPPP. Changes and updates to be logged include additions of new BMPs, replacement of failed BMPs, significant changes in the activities or their timing on the project, changes in personnel, changes in inspection and maintenance procedures, and updates to site maps, etc. 6.3 Delegation of Authority Duly Authorized Representative(s) or Position(s): Blattner Energy, Inc. Erik Sweeney 392 County Road 50 Avon, MN 56310 (320) 356-7351 23 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 7: TRAINING Describe Training Conducted: Stormwater and BMP awareness training for staff and subcontractors – The Superintendent will conduct informal training for all staff, including subcontractors, on the site. The training will focus on avoiding damage to stormwater BMPs and preventing illicit discharges. Topics include Installing and Maintaining Erosion Control BMPs, Sediment Control BMPs, Non-Stormwater BMPs, Waste Management BMPs and Materials Storage BMPs specific to the construction site. In addition, Permittee(s) must comply with training requirements under the NPDES Permit, Part III.F. Individual(s) Responsible for Training: Superintendents are responsible for educating contractors and subcontractors of stormwater and BMP requirements. Superintendents have received NPDES training from Department endorsed individual(s). Any other personnel providing inspections shall be qualified per NPDES Permit. Table 7-1: Documentation for Completion of Training Name Date Training Completed 24 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SECTION 8: CERTIFICATION AND NOTIFICATION I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations. Name: Dan Bowar Signature: Title: PE, LEED-AP Date: 04/11/2016 25 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR SWPPP APPENDICES Appendix A – Exhibits A1. Site Maps A2. Project Stormwater Management Plan A3. Project Plan Sheets Appendix B – Copy of General NPDES Permit Appendix C – NOI and EPA Authorization Email Appendix D – Inspection Form Appendix E – SWPPP Amendment Log Appendix F – Subcontractor Certifications/Agreements Appendix G – Grading and Stabilization Activities Log Appendix H – Training Log Appendix I – Delegation of Authority Appendix J – Notice of Termination (NOT) 26 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Appendix A1 – Site Maps Figure 1- USGS MAP Note: Arrows depict approximate drainage patterns off site. Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Figure 2- Location Map with Impaired waters Note: Red shading depicts impaired waters U.S. Fish & Wildlife Service Northern Long-Eared Bat Final 4(d) Rule White-Nose Syndrome Zone Around WNS/Pd Positive Counties/Districts Map Created March 31, 2016 Counties/Districts with WNS/Pd Infected Hibernacula White-Nose Syndrome Zone Per Final 4(d) Rule U.S. counties within 150 miles of positive counties/districts (Data as of 03/31/16; additional updates expected) Northern Long-Eared Bat Range (As of 04/30/2015) Northern Long-Eared Bat range and WNS Zone subject to change as new data are collected. WNS = White-Nose Syndrome Pd = Pseudogymnoascus destructans; the fungus that causes WNS 0 150 300 450 600 Miles Coordinate System: North America Equidistant Conic Datum: North American 1983 WNS Counties/Districts Data Provided By: Pennsylvania Game Commission Basemap Data: USGS Minnesota NLEB Township List and Map Page 4 Marshall Solar Energy Project Lyon County, Minnesota Figure 6 Detailed Seeding Plan 1 foot 13 feet 11 feet 1 foot Legend Solar Panel Array Mesic Forbes Mix (< 2ft tall)* “No-Mow” Grass Mix (< 1ft tall) Mesic Forbes Mix (~ 3ft tall)* “No-Mow” Grass Shade Mix (< 1ft tall) *Mesic Forb mixes may contain wildflowers and pollinator species. Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Appendix A2- Project Stormwater Management Plan Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR PAGE LEFT INTENTIONALLY BLANK EVS, Inc. Marshall Solar Lyon County, MN STORM WATER NARRATIVE 03/10/16 Prepared By: Greg Helminen Checked By: Noah Waterhouse EVS, Inc 10250 Valley View Road, Suite 140 Eden Prairie, MN 55344 I. Introduction The purpose of this report is to describe the proposed stormwater management design for the construction of a solar photovoltaic generation facility (“the project”) and document compliance with state and local stormwater requirements. The project will convert approximately 400 acres of agricultural crop land into a power generation facility. Construction will include elevated solar modules mounted on driven steel piles, concrete inverter/transformer pads, and gravel access roads. The goal of the stormwater management design is to meet or exceed the requirements of the Authorities Having Jurisdiction by reducing the rate and volume of runoff generated by the project site and controlling pollutants and sedimentation from leaving the site during construction. II. Existing Conditions The existing project property is 438.72 acres of agricultural land, most of which is currently used for annual row crops. Other than the crops and sparse trees located at the perimeter of the property in several locations, there is no other significant vegetation on the property. The project area is divided into a north half and a south half by the east/west running 290th Street. The north half of the project area drains north to a drainage ditch that runs along the northern boundary. This northern ditch collects and conveys water east towards 320th Ave E. where it enters a 48” CMP and ultimately leaves the site. The south half of the project area drains primarily south into a drainage ditch located south of the site. The runoff that is collected in the southern ditch is conveyed east towards 320th Ave E. where it enters a 36” RCP and discharges off site. A portion of the southern project area drains in a westerly direction to the adjacent property. The site has a network of drain tiles that connect to the north and the south drainage ditches. The existing project area is 100% pervious. A geotechnical investigation has been performed and shows existing soils to be primarily D type soils having an SCS curve number of approximately 89. Groundwater was not encountered in the boring depths of 5’ and 20’. See Appendix ‘A’ for Existing Drainage Exhibit. III. Proposed Development The proposed development consists of 62.25 MW AC of total solar capacity. Solar modules are mounted on racking attached to steel piles driven directly into the ground. There are multiple centrally located concrete equipment pads for inverters and transformers. The project will have road access at multiple points onto Route 9, 290th Street, and 320th Ave. Onsite access roads are aggregate and are distributed throughout the site to provide access to the equipment pads. Marshall Solar Storm Water Narrative 03/10/16 Page | 1 Grading throughout the site is done to accommodate racking and to promote effective drainage. Ground cover below the solar modules will be a short/medium height natural prairie type grass throughout the site. See Appendix ‘A’ for Existing Drainage Exhibit. IV. Jurisdictional Requirements Local jurisdictions for this project include Lyon County, Stanley Township and the MPCA. Lyon County will not be enforcing the requirements of their Conditional Use Permit since this project will be permitted by the State under the Power Plant Siting Act. Stanley Township has no permit requirements. The project will be required to comply with the Minnesota Pollution Control Agency’s NPDES Construction General Permit which has the following requirements: •Implement BMP’s to control sedimentation during construction, ie. silt fence, sediment basins, temporary stabilization, etc. •Submittal of a Notice of Intent •Develop a Storm Water Pollution Prevention Plan (SWPPP). •Post Construction volume reduction – retain the water quality volume onsite. The water quality volume is defined as 1” of runoff from new impervious surfaces that replace vegetation. Elevated solar modules are considered 50% impervious per direction from the MPCA. V. Stormwater Design Approach The proposed project will replace 7.48 acres of existing crop land with impervious gravel roads and concrete pads. In addition, 139.07 acres of impervious solar modules will be constructed, but will not replace existing vegetation since they are elevated on driven steel piles. Finally, the project substation and corresponding gravel road will create 0.85 acres of impervious surface. These additional impervious surfaces will generate an increase in stormwater runoff rate and volume, which will be mitigated to mimic undeveloped conditions. Design Assumptions •The MPCA has determined that 50% of the solar panel area should be treated as impervious in calculating post construction volume reduction. •Existing soils identified as primarily lean clays are HSG Type D •NRCS Curve Number for HSG Type D soils with straight row crops is 89 •NRCS curve number for gravel roads and inverter pads is 99 Marshall Solar Storm Water Narrative 03/10/16 Page | 2 •Seasonal high groundwater elevation is well below the elevation of any stormwater management area onsite. Volume Reduction To achieve the required post construction volume reduction, stormwater basins will be used. The stormwater basins will be located in naturally occurring depression areas. The naturally occurring outlets of the existing basins will be graded such that a maximum of 12 inches of water depth will be stored. The basins will empty slowly by infiltrating into the soil and through the existing drain tile network. These naturally occurring basins account for all of the required volume reduction. See Appendix ‘A’ for Proposed Drainage Exhibit showing the location of the basins. See Appendix ‘B’ for basin volume calculations. Rate Control To achieve post construction rate control, the approach will be to take advantage of a change in land use from annually rotated crop land to permanently vegetated grass ground cover over a majority of the site. The existing site condition of straight row crops in Hydric Soil Group D has a NRCS Curve Number (CN) of 89. When converted to a fully vegetated meadow condition, the same soil has a CN of 78. By adding the impervious gravel and concrete areas, plus accounting for the elevated solar module contributing a small amount of flow concentration, the composite curve number has been determined to be 5% higher than the vegetated meadow condition (82). The reduction in overall CN from 89 to 82 is shown to reduce the rate of stormwater runoff sufficient to satisfy the above stated requirements. Marshall Solar Storm Water Narrative 03/10/16 Page | 3 VI. Calculations and Data Volume Reduction Calculations Impervious Area: Table 1 – Impervious Area Tabulation solar panel impervious factor MODULE AREA # of modules area per module total module area factored module area ELECTRICAL EQUIPMENT AREA # of skids area per skid total skid area GRAVEL SURFACE length of gravel road width of gravel road area of gravel road PROJECT SUBSTATION area of road and gravel pad TOTAL Impervious Area 50% 282,296 21.46 6,058,072 3,029,036 ea sf sf sf 139.07 ac 69.54 ac 17 ea 398 sf 6,766 sf 0.16 ac 19,931 lf 16 lf 318,896 sf 7.32 ac 36,915 sf 0.85 ac 3,391,613 sf 77.86 ac Required Treatment Volume (Vt) *Calculated as the volume of 1” over the impervious surface Vt = 3,391,613sf x 1in x (1ft/12in) x (1ac/43560sf) = 6.42af = 282,634 cf Proposed Basin Volume (Vb) (From Appendix ‘B’) North basin volume = 12,018 cf South basin volume = 296,797 cf Total Basin Volume = Vb = 12,018cf+296,797cf = 308,815 cf Vb = 308,815 cf > 282,634 cf = Vt, OK Marshall Solar Storm Water Narrative 03/10/16 Page | 4 Rate Control Calculations Appendix ‘B’ contains the HydroCAD output report from the model of this system. HydroCAD directly implements some of the key features of TR-55, such as curve-number lookup and procedures for calculating time-of-concentration. Runoff routing method SCS TR-20 is used for this model. Table 2 - Runoff Rate Rainfall Event (Type II 24-hr) 2-year 10-year 100-year Pre-development (cfs) 284.15 492.12 939.96 Proposed (cfs) 160.98 319.64 685.40 % Reduction 43% 35% 27% Rainfall Depths Climate and Precipitation • Rainfall Frequencies per NOAA Atlas-14 Table 4 - Rainfall Events Recurrence Interval (yrs) 2 10 100 VII. 24-hour Rainfall Depth (in) 2.70 4.01 6.80 Conclusion Stormwater management requirements can be separated into two categories; construction phase requirements and post-construction phase requirements. Construction phase stormwater requirements of this project are met by obtaining the NPDES permit required by the MPCA. Post construction phase stormwater requirements are met by installing stormwater basins and changing the land use of the project area from cultivated agricultural land to nearly 100% vegetated ground cover. This land use change contributes to a reduction in rate of runoff. The stormwater basins contribute to a reduction in volume of runoff. There are no delineated wetlands on the project site. Marshall Solar Storm Water Narrative 03/10/16 Page | 5 Appendix A Drainage Exhibits Marshall Solar Storm Water Narrative 03/10/16 Page | 6 E E E E E E E E E E E E E E E E 12" PVC 15" PVC 15" CMP 48" CMP 18" PVC E E E 48" CMP 12" CMP EVS, INC. 10025 Valley View Road, Suite 140 Eden Prairie, Minnesota 55344 Phone: 952-646-0236 Fax: 952-646-0290 www.evs-eng.com 15" CMP CLIENT SCALE NORTH PROJECT MARSHALL SOLAR LOCATION LYON COUNTY, MN SHEET 12" CMP DRAINAGE PLAN E E E E E E E E E SUBMITTAL E E 60% SUBMITTAL REVISION E # DATE 18" RCP 12" PVC 18" RCP 12" CMP 24" RCP PROFESSIONAL CERTIFICATION DRAWN BY CHECKED BY T MICHELS N WATERHOUSE DATE PROJECT # 11.12.15 2015-076 SHEET NUMBER Existing x x x x x x x x x x x x x x x x x CLIENT x x x 12" PVC x 18" PVC x x x x x x x x x x x x x x x x 15" PVC 15" CMP 48" CMP 12" CMP 48" CMP EVS, INC. 10025 Valley View Road, Suite 140 Eden Prairie, Minnesota 55344 Phone: 952-646-0236 Fax: 952-646-0290 www.evs-eng.com x x x x x x x x OWNER x x x x x x 15" CMP x x x x x SCALE x x x x NORTH x x x x x x x x x x SOUTH BASIN: BOTTOM ELEV. 1105.5' HIGH WATER ELEV.=1106.5' AREA=367,085 SF VOLUME=296,797 CF x x x x x x PROJECT MARSHALL SOLAR x x LOCATION x SHEET x x LYON COUNTY, MN x x x x x x x x x 12" CMP x x DRAINAGE PLAN x x x x x x x x x x x x x x x x x x x NORTH BASIN: BOTTOM ELEV.=1102.0' HIGH WATER ELEV.=1102.5' AREA=34,714 SF VOLUME=12,018 CF x STORMWATER MANAGEMENT AREA x SUBMITTAL x x IFC SUBMITTAL x x # DATE REVISION x x x x x x x x LOW WATER CROSSING SEE DETAIL 6/C002 x x PROFESSIONAL CERTIFICATION x x x x I HEREBY CERTIFY THAT THIS PLAN, SPECIFICATION, OR REPORT WAS PREPARED BY ME OR UNDER MY DIRECT SUPERVISION AND THAT I AM A DULY LICENSED PROFESSIONAL ENGINEER UNDER THE LAWS OF THE STATE OF MINNESOTA. x x x x x x x LOW WATER CROSSING SEE DETAIL 6/C002 x x x x x ___________________ Noah Waterhouse, PE DATE 2 / 11 / 16 REGISTRATION NUMBER 46720 x x x x 24" RCP x x x T MICHELS N WATERHOUSE x x CHECKED BY DATE PROJECT # 3.11.16 2015-076 x DRAWN BY 18" RCP 12" PVC x x x 18" RCP 12" CMP x x SHEET NUMBER Proposed Appendix B HydroCAD Model Marshall Solar Storm Water Narrative 03/10/16 Page | 7 EXISTING 2S Drainage Area 2 12R Off Site Drainage 1S Drainage Area 1 4S 3S Drainage Area 4 Drainage Area 3 7S 5S 6S Drainage Area 5 Drainage Area 7 Drainage Area 6 8S Drainage Area 8 Subcat Reach Pond Link Routing Diagram for Marshall - existing Prepared by {enter your company name here}, Printed 11/20/2015 HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Type II 24-hr 2-yr Rainfall=2.70" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 2 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=26.120 ac 0.00% Impervious Runoff Depth>1.51" Flow Length=577' Slope=0.0069 '/' Tc=18.0 min CN=89 Runoff=49.89 cfs 3.283 af Subcatchment 1S: Drainage Area 1 Runoff Area=253.330 ac 0.00% Impervious Runoff Depth>1.48" Flow Length=3,916' Slope=0.0082 '/' Tc=76.4 min CN=89 Runoff=184.39 cfs 31.159 af Subcatchment 2S: Drainage Area 2 Runoff Area=29.190 ac 0.00% Impervious Runoff Depth>1.49" Flow Length=1,768' Slope=0.0045 '/' Tc=54.6 min CN=89 Runoff=27.29 cfs 3.621 af Subcatchment 3S: Drainage Area 3 Runoff Area=15.030 ac 0.00% Impervious Runoff Depth>1.48" Flow Length=1,568' Slope=0.0025 '/' Tc=66.6 min CN=89 Runoff=12.14 cfs 1.856 af Subcatchment 4S: Drainage Area 4 Runoff Area=6.900 ac 0.00% Impervious Runoff Depth>1.51" Flow Length=461' Slope=0.0240 '/' Tc=8.1 min CN=89 Runoff=18.12 cfs 0.870 af Subcatchment 5S: Drainage Area 5 Runoff Area=71.690 ac 0.00% Impervious Runoff Depth>1.50" Flow Length=2,100' Slope=0.0110 '/' Tc=40.1 min CN=89 Runoff=83.38 cfs 8.942 af Subcatchment 6S: Drainage Area 6 Runoff Area=31.230 ac 0.00% Impervious Runoff Depth>1.51" Flow Length=766' Slope=0.0160 '/' Tc=14.8 min CN=89 Runoff=65.59 cfs 3.930 af Subcatchment 7S: Drainage Area 7 Runoff Area=5.230 ac 0.00% Impervious Runoff Depth>1.51" Flow Length=666' Slope=0.0140 '/' Tc=14.2 min CN=89 Runoff=11.21 cfs 0.658 af Subcatchment 8S: Drainage Area 8 Reach 12R: Off Site Drainage Inflow=284.15 cfs 54.320 af Outflow=284.15 cfs 54.320 af Total Runoff Area = 438.720 ac Runoff Volume = 54.320 af Average Runoff Depth = 1.49" 100.00% Pervious = 438.720 ac 0.00% Impervious = 0.000 ac Type II 24-hr 2-yr Rainfall=2.70" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 3 Summary for Subcatchment 1S: Drainage Area 1 Runoff = 49.89 cfs @ 12.10 hrs, Volume= 3.283 af, Depth> 1.51" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 26.120 26.120 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 577 0.0069 0.53 Lag/CN Method, Summary for Subcatchment 2S: Drainage Area 2 Runoff = 184.39 cfs @ 12.83 hrs, Volume= 31.159 af, Depth> 1.48" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 253.330 253.330 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 76.4 3,916 0.0082 0.85 Lag/CN Method, Summary for Subcatchment 3S: Drainage Area 3 Runoff = 27.29 cfs @ 12.55 hrs, Volume= 3.621 af, Depth> 1.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 29.190 29.190 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 54.6 1,768 0.0045 0.54 Lag/CN Method, Type II 24-hr 2-yr Rainfall=2.70" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 4 Summary for Subcatchment 4S: Drainage Area 4 Runoff = 12.14 cfs @ 12.70 hrs, Volume= 1.856 af, Depth> 1.48" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 15.030 15.030 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 66.6 1,568 0.0025 0.39 Lag/CN Method, Summary for Subcatchment 5S: Drainage Area 5 Runoff = 18.12 cfs @ 11.99 hrs, Volume= 0.870 af, Depth> 1.51" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 6.900 6.900 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 461 0.0240 0.95 Lag/CN Method, Summary for Subcatchment 6S: Drainage Area 6 Runoff = 83.38 cfs @ 12.36 hrs, Volume= 8.942 af, Depth> 1.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 71.690 71.690 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 40.1 2,100 0.0110 0.87 Lag/CN Method, Type II 24-hr 2-yr Rainfall=2.70" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 5 Summary for Subcatchment 7S: Drainage Area 7 Runoff = 65.59 cfs @ 12.07 hrs, Volume= 3.930 af, Depth> 1.51" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 31.230 31.230 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 766 0.0160 0.86 Lag/CN Method, Summary for Subcatchment 8S: Drainage Area 8 Runoff = 11.21 cfs @ 12.06 hrs, Volume= 0.658 af, Depth> 1.51" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" Area (ac) 5.230 5.230 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.2 666 0.0140 0.78 Lag/CN Method, Summary for Reach 12R: Off Site Drainage Inflow Area = Inflow = Outflow = 438.720 ac, 0.00% Impervious, Inflow Depth > 1.49" for 2-yr event 284.15 cfs @ 12.61 hrs, Volume= 54.320 af 284.15 cfs @ 12.61 hrs, Volume= 54.320 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 6 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=26.120 ac 0.00% Impervious Runoff Depth>2.64" Flow Length=577' Slope=0.0069 '/' Tc=18.0 min CN=89 Runoff=85.37 cfs 5.745 af Subcatchment 1S: Drainage Area 1 Runoff Area=253.330 ac 0.00% Impervious Runoff Depth>2.59" Flow Length=3,916' Slope=0.0082 '/' Tc=76.4 min CN=89 Runoff=319.78 cfs 54.641 af Subcatchment 2S: Drainage Area 2 Runoff Area=29.190 ac 0.00% Impervious Runoff Depth>2.61" Flow Length=1,768' Slope=0.0045 '/' Tc=54.6 min CN=89 Runoff=47.20 cfs 6.345 af Subcatchment 3S: Drainage Area 3 Runoff Area=15.030 ac 0.00% Impervious Runoff Depth>2.60" Flow Length=1,568' Slope=0.0025 '/' Tc=66.6 min CN=89 Runoff=21.03 cfs 3.253 af Subcatchment 4S: Drainage Area 4 Runoff Area=6.900 ac 0.00% Impervious Runoff Depth>2.65" Flow Length=461' Slope=0.0240 '/' Tc=8.1 min CN=89 Runoff=30.71 cfs 1.522 af Subcatchment 5S: Drainage Area 5 Runoff Area=71.690 ac 0.00% Impervious Runoff Depth>2.62" Flow Length=2,100' Slope=0.0110 '/' Tc=40.1 min CN=89 Runoff=143.96 cfs 15.659 af Subcatchment 6S: Drainage Area 6 Runoff Area=31.230 ac 0.00% Impervious Runoff Depth>2.64" Flow Length=766' Slope=0.0160 '/' Tc=14.8 min CN=89 Runoff=111.99 cfs 6.876 af Subcatchment 7S: Drainage Area 7 Runoff Area=5.230 ac 0.00% Impervious Runoff Depth>2.64" Flow Length=666' Slope=0.0140 '/' Tc=14.2 min CN=89 Runoff=19.12 cfs 1.152 af Subcatchment 8S: Drainage Area 8 Reach 12R: Off Site Drainage Inflow=492.12 cfs 95.194 af Outflow=492.12 cfs 95.194 af Total Runoff Area = 438.720 ac Runoff Volume = 95.194 af Average Runoff Depth = 2.60" 100.00% Pervious = 438.720 ac 0.00% Impervious = 0.000 ac Type II 24-hr 10-yr Rainfall=4.01" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 7 Summary for Subcatchment 1S: Drainage Area 1 Runoff = 85.37 cfs @ 12.10 hrs, Volume= 5.745 af, Depth> 2.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 26.120 26.120 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 577 0.0069 0.53 Lag/CN Method, Summary for Subcatchment 2S: Drainage Area 2 Runoff = 319.78 cfs @ 12.82 hrs, Volume= 54.641 af, Depth> 2.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 253.330 253.330 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 76.4 3,916 0.0082 0.85 Lag/CN Method, Summary for Subcatchment 3S: Drainage Area 3 Runoff = 47.20 cfs @ 12.54 hrs, Volume= 6.345 af, Depth> 2.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 29.190 29.190 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 54.6 1,768 0.0045 0.54 Lag/CN Method, Type II 24-hr 10-yr Rainfall=4.01" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 8 Summary for Subcatchment 4S: Drainage Area 4 Runoff = 21.03 cfs @ 12.68 hrs, Volume= 3.253 af, Depth> 2.60" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 15.030 15.030 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 66.6 1,568 0.0025 0.39 Lag/CN Method, Summary for Subcatchment 5S: Drainage Area 5 Runoff = 30.71 cfs @ 11.99 hrs, Volume= 1.522 af, Depth> 2.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 6.900 6.900 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 461 0.0240 0.95 Lag/CN Method, Summary for Subcatchment 6S: Drainage Area 6 Runoff = 143.96 cfs @ 12.36 hrs, Volume= 15.659 af, Depth> 2.62" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 71.690 71.690 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 40.1 2,100 0.0110 0.87 Lag/CN Method, Type II 24-hr 10-yr Rainfall=4.01" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 9 Summary for Subcatchment 7S: Drainage Area 7 Runoff = 111.99 cfs @ 12.06 hrs, Volume= 6.876 af, Depth> 2.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 31.230 31.230 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 766 0.0160 0.86 Lag/CN Method, Summary for Subcatchment 8S: Drainage Area 8 Runoff = 19.12 cfs @ 12.06 hrs, Volume= 1.152 af, Depth> 2.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" Area (ac) 5.230 5.230 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.2 666 0.0140 0.78 Lag/CN Method, Summary for Reach 12R: Off Site Drainage Inflow Area = Inflow = Outflow = 438.720 ac, 0.00% Impervious, Inflow Depth > 2.60" for 10-yr event 492.12 cfs @ 12.59 hrs, Volume= 95.194 af 492.12 cfs @ 12.59 hrs, Volume= 95.194 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 10 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=26.120 ac 0.00% Impervious Runoff Depth>5.16" Flow Length=577' Slope=0.0069 '/' Tc=18.0 min CN=89 Runoff=161.05 cfs 11.224 af Subcatchment 1S: Drainage Area 1 Runoff Area=253.330 ac 0.00% Impervious Runoff Depth>5.08" Flow Length=3,916' Slope=0.0082 '/' Tc=76.4 min CN=89 Runoff=610.88 cfs 107.194 af Subcatchment 2S: Drainage Area 2 Runoff Area=29.190 ac 0.00% Impervious Runoff Depth>5.11" Flow Length=1,768' Slope=0.0045 '/' Tc=54.6 min CN=89 Runoff=89.96 cfs 12.431 af Subcatchment 3S: Drainage Area 3 Runoff Area=15.030 ac 0.00% Impervious Runoff Depth>5.09" Flow Length=1,568' Slope=0.0025 '/' Tc=66.6 min CN=89 Runoff=40.21 cfs 6.379 af Subcatchment 4S: Drainage Area 4 Runoff Area=6.900 ac 0.00% Impervious Runoff Depth>5.17" Flow Length=461' Slope=0.0240 '/' Tc=8.1 min CN=89 Runoff=57.43 cfs 2.971 af Subcatchment 5S: Drainage Area 5 Runoff Area=71.690 ac 0.00% Impervious Runoff Depth>5.13" Flow Length=2,100' Slope=0.0110 '/' Tc=40.1 min CN=89 Runoff=273.88 cfs 30.648 af Subcatchment 6S: Drainage Area 6 Runoff Area=31.230 ac 0.00% Impervious Runoff Depth>5.16" Flow Length=766' Slope=0.0160 '/' Tc=14.8 min CN=89 Runoff=210.88 cfs 13.429 af Subcatchment 7S: Drainage Area 7 Runoff Area=5.230 ac 0.00% Impervious Runoff Depth>5.16" Flow Length=666' Slope=0.0140 '/' Tc=14.2 min CN=89 Runoff=35.99 cfs 2.249 af Subcatchment 8S: Drainage Area 8 Reach 12R: Off Site Drainage Inflow=939.96 cfs 186.525 af Outflow=939.96 cfs 186.525 af Total Runoff Area = 438.720 ac Runoff Volume = 186.525 af Average Runoff Depth = 5.10" 100.00% Pervious = 438.720 ac 0.00% Impervious = 0.000 ac Type II 24-hr 100-yr Rainfall=6.80" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 11 Summary for Subcatchment 1S: Drainage Area 1 Runoff = 161.05 cfs @ 12.10 hrs, Volume= 11.224 af, Depth> 5.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 26.120 26.120 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 577 0.0069 0.53 Lag/CN Method, Summary for Subcatchment 2S: Drainage Area 2 Runoff = 610.88 cfs @ 12.81 hrs, Volume= 107.194 af, Depth> 5.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 253.330 253.330 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 76.4 3,916 0.0082 0.85 Lag/CN Method, Summary for Subcatchment 3S: Drainage Area 3 Runoff = 89.96 cfs @ 12.54 hrs, Volume= 12.431 af, Depth> 5.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 29.190 29.190 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 54.6 1,768 0.0045 0.54 Lag/CN Method, Type II 24-hr 100-yr Rainfall=6.80" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 12 Summary for Subcatchment 4S: Drainage Area 4 Runoff = 40.21 cfs @ 12.67 hrs, Volume= 6.379 af, Depth> 5.09" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 15.030 15.030 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 66.6 1,568 0.0025 0.39 Lag/CN Method, Summary for Subcatchment 5S: Drainage Area 5 Runoff = 57.43 cfs @ 11.99 hrs, Volume= 2.971 af, Depth> 5.17" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 6.900 6.900 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 461 0.0240 0.95 Lag/CN Method, Summary for Subcatchment 6S: Drainage Area 6 Runoff = 273.88 cfs @ 12.35 hrs, Volume= 30.648 af, Depth> 5.13" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 71.690 71.690 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 40.1 2,100 0.0110 0.87 Lag/CN Method, Type II 24-hr 100-yr Rainfall=6.80" Marshall - existing Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/20/2015 Page 13 Summary for Subcatchment 7S: Drainage Area 7 Runoff = 210.88 cfs @ 12.06 hrs, Volume= 13.429 af, Depth> 5.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 31.230 31.230 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 766 0.0160 0.86 Lag/CN Method, Summary for Subcatchment 8S: Drainage Area 8 Runoff = 35.99 cfs @ 12.05 hrs, Volume= 2.249 af, Depth> 5.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" Area (ac) 5.230 5.230 CN 89 Description Row crops, straight row, Good, HSG D 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.2 666 0.0140 0.78 Lag/CN Method, Summary for Reach 12R: Off Site Drainage Inflow Area = Inflow = Outflow = 438.720 ac, 0.00% Impervious, Inflow Depth > 5.10" for 100-yr event 939.96 cfs @ 12.58 hrs, Volume= 186.525 af 939.96 cfs @ 12.58 hrs, Volume= 186.525 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs PROPOSED 2S Drainage Area 2 1S Drainage Area 1 12R 4S Off Site Drainage Drainage Area 4 3S Drainage Area 2 7S 5S 6S Drainage Area 5 Drainage Area 7 Drainage Area 6 8S Drainage Area 8 Subcat Reach Pond Link Routing Diagram for Marshall - proposed Prepared by {enter your company name here}, Printed 11/12/2015 HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Type II 24-hr 2-yr Rainfall=2.70" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 2 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=26.120 ac 0.00% Impervious Runoff Depth>1.04" Flow Length=577' Slope=0.0069 '/' Tc=23.1 min CN=82 Runoff=30.02 cfs 2.266 af Subcatchment 1S: Drainage Area 1 Runoff Area=253.330 ac 0.00% Impervious Runoff Depth>1.00" Flow Length=3,916' Slope=0.0082 '/' Tc=98.1 min CN=82 Runoff=104.06 cfs 21.206 af Subcatchment 2S: Drainage Area 2 Runoff Area=28.840 ac 0.00% Impervious Runoff Depth>1.02" Flow Length=1,768' Slope=0.0045 '/' Tc=70.1 min CN=82 Runoff=15.23 cfs 2.449 af Subcatchment 3S: Drainage Area 2 Runoff Area=15.030 ac 0.00% Impervious Runoff Depth>1.01" Flow Length=1,568' Slope=0.0025 '/' Tc=85.4 min CN=82 Runoff=6.86 cfs 1.267 af Subcatchment 4S: Drainage Area 4 Runoff Area=6.900 ac 0.00% Impervious Runoff Depth>1.05" Flow Length=461' Slope=0.0240 '/' Tc=10.4 min CN=82 Runoff=11.79 cfs 0.602 af Subcatchment 5S: Drainage Area 5 Runoff Area=72.040 ac 0.00% Impervious Runoff Depth>1.03" Flow Length=2,100' Slope=0.0110 '/' Tc=51.5 min CN=82 Runoff=47.82 cfs 6.172 af Subcatchment 6S: Drainage Area 6 Runoff Area=31.230 ac 0.00% Impervious Runoff Depth>1.04" Flow Length=766' Slope=0.0160 '/' Tc=19.0 min CN=82 Runoff=40.31 cfs 2.714 af Subcatchment 7S: Drainage Area 7 Runoff Area=5.230 ac 0.00% Impervious Runoff Depth>1.04" Flow Length=666' Slope=0.0140 '/' Tc=18.2 min CN=82 Runoff=6.92 cfs 0.455 af Subcatchment 8S: Drainage Area 8 Reach 12R: Off Site Drainage Inflow=160.98 cfs 37.130 af Outflow=160.98 cfs 37.130 af Total Runoff Area = 438.720 ac Runoff Volume = 37.130 af Average Runoff Depth = 1.02" 100.00% Pervious = 438.720 ac 0.00% Impervious = 0.000 ac Type II 24-hr 2-yr Rainfall=2.70" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 3 Summary for Subcatchment 1S: Drainage Area 1 Runoff = 30.02 cfs @ 12.17 hrs, Volume= 2.266 af, Depth> 1.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 26.120 26.120 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.1 577 0.0069 0.42 Lag/CN Method, Summary for Subcatchment 2S: Drainage Area 2 Runoff = 104.06 cfs @ 13.18 hrs, Volume= 21.206 af, Depth> 1.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 253.330 253.330 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 98.1 3,916 0.0082 0.67 Lag/CN Method, Summary for Subcatchment 3S: Drainage Area 2 Runoff = 15.23 cfs @ 12.79 hrs, Volume= 2.449 af, Depth> 1.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 28.840 28.840 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 70.1 1,768 0.0045 0.42 Lag/CN Method, Type II 24-hr 2-yr Rainfall=2.70" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 4 Summary for Subcatchment 4S: Drainage Area 4 Runoff = 6.86 cfs @ 12.99 hrs, Volume= 1.267 af, Depth> 1.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 15.030 15.030 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 85.4 1,568 0.0025 0.31 Lag/CN Method, Summary for Subcatchment 5S: Drainage Area 5 Runoff = 11.79 cfs @ 12.03 hrs, Volume= 0.602 af, Depth> 1.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 6.900 6.900 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.4 461 0.0240 0.74 Lag/CN Method, Summary for Subcatchment 6S: Drainage Area 6 Runoff = 47.82 cfs @ 12.53 hrs, Volume= 6.172 af, Depth> 1.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 72.040 72.040 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 51.5 2,100 0.0110 0.68 Lag/CN Method, Type II 24-hr 2-yr Rainfall=2.70" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 5 Summary for Subcatchment 7S: Drainage Area 7 Runoff = 40.31 cfs @ 12.12 hrs, Volume= 2.714 af, Depth> 1.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 31.230 31.230 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.0 766 0.0160 0.67 Lag/CN Method, Summary for Subcatchment 8S: Drainage Area 8 Runoff = 6.92 cfs @ 12.11 hrs, Volume= 0.455 af, Depth> 1.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-yr Rainfall=2.70" * Area (ac) 5.230 5.230 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.2 666 0.0140 0.61 Lag/CN Method, Summary for Reach 12R: Off Site Drainage Inflow Area = Inflow = Outflow = 438.720 ac, 0.00% Impervious, Inflow Depth > 1.02" for 2-yr event 160.98 cfs @ 12.86 hrs, Volume= 37.130 af 160.98 cfs @ 12.86 hrs, Volume= 37.130 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Marshall - proposed Type II 24-hr 10-yr Rainfall=4.01" Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 6 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=26.120 ac 0.00% Impervious Runoff Depth>2.03" Flow Length=577' Slope=0.0069 '/' Tc=23.1 min CN=82 Runoff=58.86 cfs 4.425 af Subcatchment 1S: Drainage Area 1 Runoff Area=253.330 ac 0.00% Impervious Runoff Depth>1.97" Flow Length=3,916' Slope=0.0082 '/' Tc=98.1 min CN=82 Runoff=206.57 cfs 41.607 af Subcatchment 2S: Drainage Area 2 Runoff Area=28.840 ac 0.00% Impervious Runoff Depth>2.00" Flow Length=1,768' Slope=0.0045 '/' Tc=70.1 min CN=82 Runoff=30.26 cfs 4.796 af Subcatchment 3S: Drainage Area 2 Runoff Area=15.030 ac 0.00% Impervious Runoff Depth>1.98" Flow Length=1,568' Slope=0.0025 '/' Tc=85.4 min CN=82 Runoff=13.62 cfs 2.483 af Subcatchment 4S: Drainage Area 4 Runoff Area=6.900 ac 0.00% Impervious Runoff Depth>2.04" Flow Length=461' Slope=0.0240 '/' Tc=10.4 min CN=82 Runoff=22.71 cfs 1.174 af Subcatchment 5S: Drainage Area 5 Runoff Area=72.040 ac 0.00% Impervious Runoff Depth>2.01" Flow Length=2,100' Slope=0.0110 '/' Tc=51.5 min CN=82 Runoff=94.76 cfs 12.072 af Subcatchment 6S: Drainage Area 6 Runoff Area=31.230 ac 0.00% Impervious Runoff Depth>2.04" Flow Length=766' Slope=0.0160 '/' Tc=19.0 min CN=82 Runoff=78.73 cfs 5.298 af Subcatchment 7S: Drainage Area 7 Runoff Area=5.230 ac 0.00% Impervious Runoff Depth>2.04" Flow Length=666' Slope=0.0140 '/' Tc=18.2 min CN=82 Runoff=13.49 cfs 0.887 af Subcatchment 8S: Drainage Area 8 Reach 12R: Off Site Drainage Inflow=319.64 cfs 72.741 af Outflow=319.64 cfs 72.741 af Total Runoff Area = 438.720 ac Runoff Volume = 72.741 af Average Runoff Depth = 1.99" 100.00% Pervious = 438.720 ac 0.00% Impervious = 0.000 ac Type II 24-hr 10-yr Rainfall=4.01" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 7 Summary for Subcatchment 1S: Drainage Area 1 Runoff = 58.86 cfs @ 12.16 hrs, Volume= 4.425 af, Depth> 2.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 26.120 26.120 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.1 577 0.0069 0.42 Lag/CN Method, Summary for Subcatchment 2S: Drainage Area 2 Runoff = 206.57 cfs @ 13.14 hrs, Volume= 41.607 af, Depth> 1.97" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 253.330 253.330 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 98.1 3,916 0.0082 0.67 Lag/CN Method, Summary for Subcatchment 3S: Drainage Area 2 Runoff = 30.26 cfs @ 12.75 hrs, Volume= 4.796 af, Depth> 2.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 28.840 28.840 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 70.1 1,768 0.0045 0.42 Lag/CN Method, Type II 24-hr 10-yr Rainfall=4.01" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 8 Summary for Subcatchment 4S: Drainage Area 4 Runoff = 13.62 cfs @ 12.98 hrs, Volume= 2.483 af, Depth> 1.98" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 15.030 15.030 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 85.4 1,568 0.0025 0.31 Lag/CN Method, Summary for Subcatchment 5S: Drainage Area 5 Runoff = 22.71 cfs @ 12.02 hrs, Volume= 1.174 af, Depth> 2.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 6.900 6.900 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.4 461 0.0240 0.74 Lag/CN Method, Summary for Subcatchment 6S: Drainage Area 6 Runoff = 94.76 cfs @ 12.52 hrs, Volume= 12.072 af, Depth> 2.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 72.040 72.040 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 51.5 2,100 0.0110 0.68 Lag/CN Method, Type II 24-hr 10-yr Rainfall=4.01" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 9 Summary for Subcatchment 7S: Drainage Area 7 Runoff = 78.73 cfs @ 12.12 hrs, Volume= 5.298 af, Depth> 2.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 31.230 31.230 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.0 766 0.0160 0.67 Lag/CN Method, Summary for Subcatchment 8S: Drainage Area 8 Runoff = 13.49 cfs @ 12.11 hrs, Volume= 0.887 af, Depth> 2.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=4.01" * Area (ac) 5.230 5.230 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.2 666 0.0140 0.61 Lag/CN Method, Summary for Reach 12R: Off Site Drainage Inflow Area = Inflow = Outflow = 438.720 ac, 0.00% Impervious, Inflow Depth > 1.99" for 10-yr event 319.64 cfs @ 12.84 hrs, Volume= 72.741 af 319.64 cfs @ 12.84 hrs, Volume= 72.741 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Marshall - proposed Type II 24-hr 100-yr Rainfall=6.80" Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 10 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=26.120 ac 0.00% Impervious Runoff Depth>4.40" Flow Length=577' Slope=0.0069 '/' Tc=23.1 min CN=82 Runoff=124.61 cfs 9.570 af Subcatchment 1S: Drainage Area 1 Runoff Area=253.330 ac 0.00% Impervious Runoff Depth>4.28" Flow Length=3,916' Slope=0.0082 '/' Tc=98.1 min CN=82 Runoff=443.66 cfs 90.376 af Subcatchment 2S: Drainage Area 2 Runoff Area=28.840 ac 0.00% Impervious Runoff Depth>4.33" Flow Length=1,768' Slope=0.0045 '/' Tc=70.1 min CN=82 Runoff=65.02 cfs 10.400 af Subcatchment 3S: Drainage Area 2 Runoff Area=15.030 ac 0.00% Impervious Runoff Depth>4.30" Flow Length=1,568' Slope=0.0025 '/' Tc=85.4 min CN=82 Runoff=29.18 cfs 5.389 af Subcatchment 4S: Drainage Area 4 Runoff Area=6.900 ac 0.00% Impervious Runoff Depth>4.41" Flow Length=461' Slope=0.0240 '/' Tc=10.4 min CN=82 Runoff=47.43 cfs 2.538 af Subcatchment 5S: Drainage Area 5 Runoff Area=72.040 ac 0.00% Impervious Runoff Depth>4.36" Flow Length=2,100' Slope=0.0110 '/' Tc=51.5 min CN=82 Runoff=202.66 cfs 26.150 af Subcatchment 6S: Drainage Area 6 Runoff Area=31.230 ac 0.00% Impervious Runoff Depth>4.40" Flow Length=766' Slope=0.0160 '/' Tc=19.0 min CN=82 Runoff=166.09 cfs 11.457 af Subcatchment 7S: Drainage Area 7 Runoff Area=5.230 ac 0.00% Impervious Runoff Depth>4.40" Flow Length=666' Slope=0.0140 '/' Tc=18.2 min CN=82 Runoff=28.44 cfs 1.919 af Subcatchment 8S: Drainage Area 8 Reach 12R: Off Site Drainage Inflow=685.40 cfs 157.798 af Outflow=685.40 cfs 157.798 af Total Runoff Area = 438.720 ac Runoff Volume = 157.798 af Average Runoff Depth = 4.32" 100.00% Pervious = 438.720 ac 0.00% Impervious = 0.000 ac Type II 24-hr 100-yr Rainfall=6.80" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 11 Summary for Subcatchment 1S: Drainage Area 1 Runoff = 124.61 cfs @ 12.16 hrs, Volume= 9.570 af, Depth> 4.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 26.120 26.120 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.1 577 0.0069 0.42 Lag/CN Method, Summary for Subcatchment 2S: Drainage Area 2 Runoff = 443.66 cfs @ 13.10 hrs, Volume= 90.376 af, Depth> 4.28" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 253.330 253.330 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 98.1 3,916 0.0082 0.67 Lag/CN Method, Summary for Subcatchment 3S: Drainage Area 2 Runoff = 65.02 cfs @ 12.72 hrs, Volume= 10.400 af, Depth> 4.33" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 28.840 28.840 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 70.1 1,768 0.0045 0.42 Lag/CN Method, Type II 24-hr 100-yr Rainfall=6.80" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 12 Summary for Subcatchment 4S: Drainage Area 4 Runoff = 29.18 cfs @ 12.94 hrs, Volume= 5.389 af, Depth> 4.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 15.030 15.030 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 85.4 1,568 0.0025 0.31 Lag/CN Method, Summary for Subcatchment 5S: Drainage Area 5 Runoff = 47.43 cfs @ 12.02 hrs, Volume= 2.538 af, Depth> 4.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 6.900 6.900 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.4 461 0.0240 0.74 Lag/CN Method, Summary for Subcatchment 6S: Drainage Area 6 Runoff = 202.66 cfs @ 12.51 hrs, Volume= 26.150 af, Depth> 4.36" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 72.040 72.040 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 51.5 2,100 0.0110 0.68 Lag/CN Method, Type II 24-hr 100-yr Rainfall=6.80" Marshall - proposed Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 11/12/2015 Page 13 Summary for Subcatchment 7S: Drainage Area 7 Runoff = 166.09 cfs @ 12.11 hrs, Volume= 11.457 af, Depth> 4.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 31.230 31.230 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.0 766 0.0160 0.67 Lag/CN Method, Summary for Subcatchment 8S: Drainage Area 8 Runoff = 28.44 cfs @ 12.10 hrs, Volume= 1.919 af, Depth> 4.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=6.80" * Area (ac) 5.230 5.230 CN 82 Description Meadow, non-grazed, HSG D +5% for solar modules, inverters, gravel roads 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.2 666 0.0140 0.61 Lag/CN Method, Summary for Reach 12R: Off Site Drainage Inflow Area = Inflow = Outflow = 438.720 ac, 0.00% Impervious, Inflow Depth > 4.32" for 100-yr event 685.40 cfs @ 12.80 hrs, Volume= 157.798 af 685.40 cfs @ 12.80 hrs, Volume= 157.798 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs BASIN VOLUMES 2P North Stormwater Basin 1P South Stormwater Basin Subcat Reach Pond Link Routing Diagram for Marshall - basin volumes Prepared by {enter your company name here}, Printed 3/10/2016 HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Rainfall not specified Marshall - basin volumes Prepared by {enter your company name here} HydroCAD® 10.00-14 s/n 01636 © 2015 HydroCAD Software Solutions LLC Printed 3/10/2016 Page 3 Summary for Pond 1P: South Stormwater Basin Volume #1 Elevation (feet) 1,105.50 1,106.50 Invert 1,105.50' Avail.Storage 296,797 cf Surf.Area (sq-ft) 226,509 367,085 Storage Description Custom Stage Data (Prismatic)Listed below (Recalc) Inc.Store (cubic-feet) 0 296,797 Cum.Store (cubic-feet) 0 296,797 Summary for Pond 2P: North Stormwater Basin Volume #1 Elevation (feet) 1,102.00 1,102.50 Invert 1,102.00' Avail.Storage 12,018 cf Surf.Area (sq-ft) 13,358 34,714 Storage Description Custom Stage Data (Prismatic)Listed below (Recalc) Inc.Store (cubic-feet) 0 12,018 Cum.Store (cubic-feet) 0 12,018 Stormwater Pollution Prevention Plan (SWPPP) MARSHALL SOLAR Appendix A3- Project Plan Sheets

Stormwater Pollution Prevention Plan (swppp)

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