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P:\Projects\Projects - 2023\12236128 - New Stillwater Elementary School - Wold\C. Design\Drawing Files\12236128 - C001 SWPPP.dwg
<br /> 08-23-2024 PRELIMINARYPLAT SUBMITTALRevisionsDescriptionDateNumNorthCheck:Drawn:Date:Comm:MTH08-23-2024122361283524 Labore RoadWhite Bear Lake, MN 55110651.481.9120 (f) 651.481.9201www.larsonengr.comC 2024 Larson Engineering, Inc. All rights reserved.3524 Labore RoadWhite Bear Lake, MN 55110651.481.9120 (f) 651.481.9201www.larsonengr.comLarsonEngineering, Inc.Greg A. Buchal, P.E.Date: Lic. No.:08.23.202423793I hereby certify that this plan, specifications or reportwas prepared by me or under my direct supervisionand that I am a duly licensed Professional Engineerunder the laws of the state of Minnesota.INDEPENDENT SCHOOLDISTRICT #834New Lake ElmoElementary School1875 Greeley St S, Stillwater, MN55082Corner of 10th Streen North andLake Elmo Avenue NorthLake Elmo MN 55042AFEDCBA12345678MNGENERAL SWPPP REQUIREMENTS AND NOTES:TEMPORARY EROSION PREVENTION PRACTICES (SECTION 8)1.Prior to beginning any construction work at the site, locations of areas not to be disturbed must bedelineated (e.g., with flags, stakes, signs, silt fence, snow fence, etc.) throughout the project site.2.Minimize the need for disturbance of portions of the project with steep slopes. For those slopedareas which must be disturbed, use techniques such as phasing and stabilization practicesdesigned for steep slopes (e.g., slope draining and terracing).3.Stabilize all exposed soil areas (including stockpiles). Stabilization must be initiated immediately tolimit soil erosion whenever any construction activity has permanently or temporarily ceased on anyportion of the site and will not resume for a period exceeding 14 calendar days (or 7 days if withinone mile of an identified impaired water). Stabilization must be completed no later than 14calendar days (or 7 days if within one mile of an identified impaired water) after the constructionactivity has ceased.4.Stabilization is not required on constructed base components of roads, parking lots, and similarsurfaces. Stabilization is not required on temporary stockpiles without significant silt, clay ororganic components (e.g., clean aggregate stockpiles, demolition concrete stockpiles, sandstockpiles) but sediment controls must be placed at the base of the stockpile.5.For Public Waters that the Minnesota Department of Natural Resources has promulgated “work inwater restrictions” during specified fish spawning time frames, all exposed soil areas that are within200 feet of the water's edge, and drain to these waters must complete the stabilization activitieswithin 24 hours during the restriction period.6.Stabilize the normal wetted perimeter of the last 200 linear feet of temporary or permanentdrainage ditches or swales that drain water from the site within 24 hours after connecting to asurface water or property edge. Stabilize remaining portions of temporary or permanent ditches orswales within 14 calendar days (or 7 days if within one mile of an identified impaired water) afterconnecting to a surface water or property edge and construction in that portion of the ditchtemporarily or permanently ceases.7.Temporary or permanent ditches or swales being used as sediment containment systems duringconstruction (with properly designed rock-ditch checks, bio rolls, silt dikes, etc.) do not need to bestabilized during the temporary period of use as a sediment containment system. These areasmust be stabilized within 24 hours after no longer being used for as a sediment containmentsystem.8.Applying mulch, hydromulch, tackifier, polyacrylamide or similar erosion prevention practices is notacceptable within any portion of the normal wetted perimeter of a temporary or permanentdrainage ditch or swale section with a continuous slope of greater than 2 percent.9.Pipe outlets must be provided with temporary or permanent energy dissipation within 24 hoursafter connection to a surface water or permanent stormwater treatment system.10.Route water around unstabilized areas on the site and to reduce erosion, unless infeasible. Useerosion controls and velocity dissipation devices such as check dams, sediment traps, riprap, orgrouted riprap at outlets within and along the length of any constructed stormwater conveyancechannel, and at any outlet, to provide a non‐erosive flow velocity, to minimize erosion of channelsand their embankments, outlets, adjacent stream banks, slopes, and downstream waters duringdischarge conditions.11.Unless infeasible due to lack of pervious or vegetated areas, direct discharges from BMPs tovegetated areas of the site (including any natural buffers) in order to increase sediment removaland maximize stormwater infiltration. Use velocity dissipation devices if necessary to preventerosion when directing stormwater to vegetated areas.12.Infiltration areas shall not be excavated until all upstream areas have been stabilized and/orupstream BMPs are in place to properly prevent sediment deposition. Only low impact equipmentshall be allowed in infiltration areas which shall be clearly identified, staked, and marked/fencedoff.13.Project phasing shall be implemented to ensure land disturbance and temporary erosion controlmeasures can be effectively inspected and maintained throughout the duration of the project inaccordance with the Inspection and Maintenance requirements of Section 11.TEMPORARY SEDIMENT CONTROL PRACTICES (SECTION 9)1.Sediment control practices must be established on all down gradient perimeters and be locatedupgradient of any buffer zones. The perimeter sediment control practices must be in place beforeany upgradient land‐disturbing activities begin. These practices shall remain in place until FinalStabilization has been established.2.If downgradient sediment controls become overloaded, based on frequent failure or excessivemaintenance requirements, additional upgradient sediment control practices or redundant BMPsshall be installed to eliminate the overloading concerns. All changes shall be recorded in theSWPPP.3.Temporary or permanent drainage ditches and sediment basins designed as part of a sedimentcontainment system (e.g., ditches with rock-check dams) require sediment control practices onlyas appropriate for site conditions.4.A floating silt curtain placed in the water is not an acceptable sediment control BMP except whenworking on a shoreline or below the waterline. Immediately after construction activity (e.g.,installation of rip rap along the shoreline) in that area is complete, upland perimeter controlpractices shall be installed if exposed soils still drain to a surface water.5.Re‐install all sediment control practices that have been adjusted or removed to accommodateshort‐term activities such as clearing or grubbing, or passage of vehicles, immediately after theshort‐term activity has been completed. Complete any short‐term activity that requires removal ofsediment control practices as quickly as possible and re‐install sediment control practices beforethe next precipitation event even if the short‐term activity is not complete.6.All storm drain inlets must be protected by appropriate BMPs during construction until all sourceswith potential for discharging to the inlet have been stabilized. Inlet protection may be removed fora particular inlet if a specific safety concern (street flooding/freezing) has been identified by thePermittee(s) or the jurisdictional authority (e.g., city/county/township/MnDOT engineer).ThePermittee(s) must document the need for removal in the SWPPP.7.Temporary soil stockpiles must have silt fence or other effective sediment controls, and cannot beplaced in any natural buffers or surface waters, including stormwater conveyances such as curband gutter systems, or conduits and ditches unless there is a bypass in place for the stormwater.8.Where vehicle traffic leaves any part of the site (or onto paved roads within the site) install avehicle tracking BMP to minimize the track out of sediment from the construction site. Examples ofvehicle tracking BMPs include (but are not limited to) rock pads, mud mats, slash mulch, concreteor steel wash racks, or equivalent systems. Use street sweeping if such vehicle tracking BMPs arenot adequate to prevent sediment from being tracked onto the street.9.The Permittee(s) must install temporary sedimentation basins as required in accordance withpermit requirements.10.Minimize soil compaction by restricting vehicle access in areas where final vegetative stabilizationwill occur, unless otherwise infeasible.11.Discharges from BMPs shall be directed to vegetated areas unless infeasible.12.Preserve a 50 foot natural buffer or (if a buffer is infeasible on the site) provide redundant (double)perimeter sediment controls when a surface water is located within 50 feet of the project's earthdisturbances and stormwater flows to the surface water.13.Perimeter sediment controls shall be installed at least 5 feet apart unless limited by lack ofavailable space. Natural buffers are not required adjacent to road ditches, judicial ditches, countyditches, stormwater conveyance channels, storm drain inlets, and sediment basins. If preservingthe buffer is infeasible, the reasons for which shall be recorded in the SWPPP.14.The use of polymers, flocculants, or other sedimentation treatment chemicals, if used on theproject, shall be used in accordance with accepted engineering practices, dosing specifications,and sediment removal design specifications provided by the product manufacturer or supplier. Useconventional erosion and sediment controls prior to the chemical addition to ensure effectivetreatment. Chemicals may only be applied where treated stormwater is directed to a sedimentcontrol system which allows or filtration of settlement of the floc prior to discharge.15.If the proposed project as shown on the plans has 10 or more acres draining to a common locationor 5 acres or more if the site is within one mile of a special or impaired water (as identified inSection II - Receiving Waters and Environmentally Sensitive Areas), then a temporary sedimentbasin must be constructed as shown on the plans. Temporary sediment basins will have aminimum of 3,600 cubic feet of storage per acre draining to the basin. The basin outlet shallprovide for discharging water from the surface to minimize discharging of pollutants. A stabilizedemergency overflow shall be constructed.DEWATERING AND BASIN DRAINING (SECTION 10)1.Discharge turbid or sediment‐laden waters related to dewatering or basin draining (e.g., pumpeddischarges, trench/ditch cuts for drainage) to a temporary or permanent sediment basin on theproject site unless infeasible. Discharge from the temporary or permanent sedimentation basins tosurface waters if the basin water has been visually checked to ensure adequate treatment hasbeen obtained in the basin and that nuisance conditions will not result from the discharge. If thewater cannot be discharged to a sedimentation basin prior to entering the surface water, it must betreated with the appropriate BMPs, such that the discharge does not adversely affect the receivingwater or downstream properties.2.Discharge water that contains oil or grease, must use an oil‐water separator or suitable filtrationdevice (e.g. cartridge filters, absorbents pads) prior to discharging the water.3.All water from dewatering or basin‐draining activities must be discharged in a manner that doesnot cause nuisance conditions, erosion in receiving channels or downslope properties, erosion orscour in the immediate vicinity of discharge points, or inundation in wetlands causing significantadverse impact to the wetland.4.The use of filters with backwash water, haul the backwash water away for disposal, return thebackwash water to the beginning of the treatment process, or incorporate the backwash water intothe site in a manner that does not cause erosion. Discharge backwash water to the sanitary sewerif permission is granted by the sanitary sewer authority. Replace and clean the filter media used indewatering devices when required to retain adequate function.INSPECTIONS AND MAINTENANCE (SECTION 11)1.Owner and Contractor shall ensure that a trained person (as identified in item 21.2.b) of the permit willinspect the entire construction site at a minimum:- Once every seven (7) days during active construction, and- Within 24 hours after a rainfall event greater than 1/2 inch in 24 hours2.Inspect all erosion prevention and sediment control BMPs and Pollution Prevention ManagementMeasures to ensure integrity and effectiveness during all routine and post‐rainfall event inspections. Allnonfunctional BMPs must be repaired, replaced, or supplemented with functional BMPs by the end of thenext business day after discovery, or as soon as field conditions allow access unless another time frameis specified below. Investigate and comply with the following Inspection and Maintenance requirements:a.All perimeter control devices must be repaired, replaced, or supplemented when they becomenonfunctional or the sediment reaches one‐half (1/2) of the height of the device. These repairs mustbe made by the end of the next business day after discovery, or thereafter as soon as field conditionsallow access.b.Temporary and permanent sedimentation basins must be drained and the sediment removed whenthe depth of sediment collected in the basin reaches one‐half (1/2) the storage volume. Drainage andremoval must be completed within 72 hours of discovery, or as soon as field conditions allow access.c.Inspect and photograph dewatering discharges at the beginning and at least once every 24 hoursduring operation.d.Surface waters, including drainage ditches and conveyance systems, must be inspected for evidenceof erosion and sediment deposition during each inspection. Remove all deltas and sedimentdeposited in surface waters, including drainage ways, catch basins, and other drainage systems, andrestabilize the areas where sediment removal results in exposed soil. The removal and stabilizationmust take place within seven (7) days of discovery unless precluded by legal, regulatory, or physicalaccess constraints. Use all reasonable efforts to obtain access. If precluded, removal and stabilizationmust take place within seven (7) calendar days of obtaining access. Contact all local, regional, stateand federal authorities and receiving any applicable permits, prior to conducting any work in surfacewaters.e.Construction site vehicle exit locations must be inspected for evidence of off‐site sediment trackingonto paved surfaces. Tracked sediment must be removed from all paved surfaces both on and off sitewithin 24 hours of discovery, or if applicable, within a shorter time.f.Streets and other areas adjacent to the project must be inspected for evidence of off‐siteaccumulations of sediment. If sediment is present, it must be removed in a manner and at a frequencysufficient to minimize off‐site impacts (e.g., fugitive sediment in streets could be washed into stormsewers by the next rain and/or pose a safety hazard to users of public streets).5.Inspection frequency adjustment:a.Inspections of areas with permanent cover can be reduced to once per month, even if constructionactivity continues on other portions of the site; orb.where sites have permanent cover on all exposed soil and no construction activity is occurringanywhere on the site, inspections can be reduced to once per month and, after 12 months, may besuspended completely until construction activity resumes. The MPCA may require inspections toresume if conditions warrant; orc.where construction activity has been suspended due to frozen ground conditions, inspections may besuspended. Inspections must resume within 24 hours of runoff occurring, or upon resumingconstruction, whichever comes first.3.All inspections and maintenance activities within 24 hours of being conducted must be recorded andretained in the SWPPP. These records must include:a.Date and time of inspectionsb.Name of person(s) conducting inspectionsc.Findings of inspections, including the specific location where corrective actions are neededd.Corrective actions taken (including dates, times, and party completing maintenance activities)e.Date and amount of all rainfall events greater than 1/2 inch (0.5 inches) in 24 hours. Rainfall amountsmust be obtained by a properly maintained rain gauge installed onsite, a weather station that is within1 mile of your location or a weather reporting system that provides site specific rainfall data from radarsummaries.f.If any discharge is observed to be occurring during the inspection, a record of all points of the propertyfrom 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 withinseven (7) calendar days.4.All infiltration areas must be inspected to ensure that no sediment from ongoing construction activity isreaching the infiltration area. All infiltration areas must be inspected to ensure that equipment is not beingdriven across the infiltration area.POLLUTION PREVENTION MANAGEMENT MEASURES (SECTION 12)Implement the following pollution prevention management measures on the site:1.Storage, Handling, and Disposal of Construction Products, Materials, and Wastes shall comply with thefollowing to minimize the exposure to stormwater of any of the products, materials, or wastes. Productsor wastes which are either not a source of contamination to stormwater or are designed to be exposed tostormwater are not held to this requirement:a.Building products that have the potential to leach pollutants must be under cover (e.g., plasticsheeting or temporary roofs) to prevent the discharge of pollutants or protected by a similarly effectivemeans designed to minimize contact with stormwater.b.Pesticides, herbicides, insecticides, fertilizers, treatment chemicals, and landscape materials must beunder cover (e.g., plastic sheeting or temporary roofs) to prevent the discharge of pollutants orprotected by similarly effective means designed to minimize contact with stormwater.c.Hazardous materials, toxic waste, (including oil, diesel fuel, gasoline, hydraulic fluids, paint solvents,petroleum‐based products, wood preservatives, additives, curing compounds, and acids) must beproperly stored in sealed containers to prevent spills, leaks or other discharge. Restricted accessstorage areas must be provided to prevent vandalism. Storage and disposal of hazardous waste orhazardous materials must be in compliance with Minn. R. ch. 7045 including secondary containmentas applicable.d.Solid waste must be stored, collected and disposed of properly in compliance with Minn. R. ch. 7035.e.Portable toilets must be positioned so that they are secure and will not be tipped or knocked over.Sanitary waste must be disposed of properly in accordance with Minn. R. ch. 7041.2.Fueling and Maintenance of Equipment or Vehicles; Spill Prevention and Response: Take reasonablesteps to prevent the discharge of spilled or leaked chemicals, including fuel, from any area wherechemicals or fuel will be loaded or unloaded including the use of drip pans or absorbents unlessinfeasible. Conduct fueling in a contained area unless infeasible. Ensure adequate supplies are availableat all times to clean up discharged materials and that an appropriate disposal method is available forrecovered spilled materials. Report and clean up spills immediately as required by Minn. Stat. § 115.061,using dry clean up measures where possible.3.Vehicle and equipment washing: Wash the exterior of vehicles or equipment on the project site, washingmust be limited to a defined area of the site. Runoff from the washing area must be contained in asediment basin or other similarly effective controls and waste from the washing activity must be properlydisposed of. Properly use and store soaps, detergents, or solvents. No engine degreasing is allowed onsite.4.Concrete and other washouts waste: Provide effective containment for all liquid and solid wastesgenerated by washout operations (concrete, stucco, paint, form release oils, curing compounds and otherconstruction materials) related to the construction activity. The liquid and solid washout wastes must notcontact the ground, and the containment must be designed so that it does not result in runoff from thewashout operations or areas. Liquid and solid wastes must be disposed of properly and in compliancewith MPCA rules. A sign must be installed adjacent to each washout facility that requires site personnelto utilize the proper facilities for disposal of concrete and other washout wastes.SWPPP AMENDMENTS (SECTION 6):1.One of the individuals described in item 21.2.a or 21.2.b of the permit or another qualifiedindividual must complete all SWPPP changes. Changes involving the use of less stringent BMPsmust include a justification describing how the replacement BMP is effective for the sitecharacteristics.2.The SWPPP shall be amended to include additional or modified BMPs as necessary to correctproblems identified or address situations whenever there is a change in design, construction,operation, maintenance, weather or seasonal conditions having a significant effect on thedischarge of pollutants to surface waters or groundwater.3.The SWPPP shall be amended to include additional or modified BMPs as necessary to correctproblems identified or address situations whenever inspections or investigations by the site owneror operator, USEPA or MPCA officials indicate the SWPPP is not effective in eliminating orsignificnatly minimizing the ischarge of pollutants to surface waters or groundwater or thedischarges are cuasing water quality standard exceedances (e.g., nuisance conditions as definedin Minn. R. 7050.0210, subp. 2 or the SWPPP is not consistend with the ofjectives of the USEPAapproved TMDL.BMP SELECTION AND INSTALLATION (SECTION 7):1.All BMPs identified in the SWPPP document and construction plans shall be selected, installed,and maintained in an appropriate and functional manner in accordance with relevant manufacturerspecifications and accepted engineering practices.2.Do not disturb more land (i.e., phasing) than can be effectively inspected and maintained inaccordance with Section 11.PERMIT TERMINATION (SECTIONS 4 AND 13)1.Permittees must submit a NOT within 30 days after all termination conditions listed in Section 13are complete.2.Permittees must submit a NOT within 30 days after selling or otherwise legally transferring theentire site, including permit responsibility for roads (e.g., street sweeping) and stormwaterinfrastructure final clean out, or transferring portions of a site to another party. The permittees'coverage under the permit terminates at midnight on the submission date of the NOT.3.Permittees may terminate permit coverage prior to completion of all construction activity if theymeet all of the following conditions:a.Construction activity has ceased for at least 90 days; andb.at least 90 percent (by area) of all originally proposed construction activity has been completedand permanent cover has been established on those areas; andc.on areas where construction activity is not complete, permanent cover has been established;andd.the site complies with items 13.3 through 13.7 of the permit.After permit coverage is terminated under this item, any subsequent development on the remainingportions of the site will require permit coverage if the subsequent development itself or as part ofthe remaining common plan of development or sale will result in land disturbing activity of one (1)or more acres in size.4.Permittees may terminate coverage upon MPCA approval after submitting informationdocumenting the owner canceled the project.5.Permittees must complete all construction activity and must install permanent cover over all areasprior to submitting the NOT. Vegetative cover must consist of a uniform perennial vegetation with adensity of 70 percent of its expected final growth. Vegetation is not required where the function of aspecific area dictates no vegetation, such as impervious surfaces or the base of a sand filter.6.Permittees must clean the permanent stormwater system of any accumulated sediment and mustensure the system meets all applicable requirements in Section 15 through 19 of the permit and isoperating as designed.7.Permittees must remove all sediment from conveyance systems prior to submitting the NOT.8.Permittees must remove all temporary synthetic erosion prevention and sediment control BMPsprior to submitting the NOT. BMPs designed to decompose on-site may be left in place.9.For residential construction only, permit coverage terminates on individual lots if the structures arefinished and temporary erosion prevention and downgradient perimeter control is complete, theresidence sells to the homeowner, and the permittee distributes the MPCA's "Homeowner FactSheet" to the homeowner.10.For construction projects on agricultural land (e.g., pipelines across cropland), disturbed land mustbe returned to its preconstruction agricultural condition prior to submitting the NOT.11.When submitting the NOT, permittees must include either ground or aerial photographs showingvegetative cover requirements have been met as listed above. All submitted photographs shallinclude the date and specific site location.LONG TERM OPERATION AND MAINTENANCE:1.Upon the completion of construction activity and NPDES permit termination, in accordance withSections 4 and 13, the Property Owner shall become the responsible party for long term operationand maintenance (O&M) of all permanent stormwater management features under this project.2.All associated operations, inspections, maintenance, and record keeping shall be performed bytrained individual(s) familiar with the site stormwater management system.3.Record keeping of inspections and maintenance items shall be maintained by the Owner inaccordance with applicable Maintenance Agreements/Declarations as required by localjurisdictional authorities.SWPPPC002
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