|
ALL CONSTRUCTION ACTIVITIES MUST MEET THE REQUIREMENTS OF THE MPCA'S GENERAL PERMIT
<br />AUTHORIZATION TO DISCHARGE STORMWATER ASSOCIATED WITH CONSTRUCTION ACTIVITY UNDER THE
<br />NPDES/SDS PROGRAM (MNR100001). All sheets of this planset, as well as the related Project SWMP,
<br />are hereby referenced as part of this SWPPP; any related pages shall be revised as appropriate
<br />for differing site conditions. Specific reference permit sections included in parentheses throughout.
<br />SITE AND CONSTRUCTION DESCRIPTION:
<br />This project includes site grading for a new rural residential subdivision in the City of Orono, Hennepin County, MN
<br />(Lat: 44.975262, Long:-92.639664).
<br />The site work will include disturbance of 9.52 of the 25.35 acres for the construction of one public street (50' ROW)
<br />and cul-de-sac to serve 5 rural residential lots, as well as associated driveways, stormwater management, site
<br />grading, septic, well, and landscaping features. Approximately 10,000 CY of material will be excavated and relocated
<br />on -site, and all areas will be stabilized and restored as indicated in the plans. Riprap will be installed at all storm
<br />sewer and culvert pipe outlets.
<br />The existing site contains one house and small outbuildings, and is otherwise an undeveloped natural area. No
<br />groundwater or soil contamination is anticipated (16.15).
<br />The Contractor shall sign the MPCA NPDES Construction Stormwater Permit application as "Operator" and be solely
<br />responsible for meeting the erosion and sediment control requirements of the permit.
<br />Disturbed Area: 9.52 acres
<br />Pre -Construction Impervious Area: 0.55 acres
<br />Post -Construction Impervious Area: 1.88 acres
<br />Newly Created Impervious Area: 1.33 acres
<br />Permanent Stormwater Treatment Required (If >1.0 acre): YES
<br />PERMANENT
<br />STORMWATER MANAGEMENT:
<br />Permanent
<br />stormwater management is required
<br />by the MPCA and Minnehaho Creek Watershed District
<br />(MCWD), and is
<br />described in detail in the project Stormwater Management Plan (SWMP) document. In summary, the
<br />site has been
<br />designed to
<br />treat a WQV equivalent to 1 inch
<br />of infiltration from the site impervious area. Filtration
<br />is planned for
<br />part of the
<br />treatment, with the WQV increased
<br />by a factor of 2 for the area treated by filtration rather than
<br />infiltration.
<br />Discharge rates from the site have
<br />been maintained.
<br />Soil mapping for the area indicates a prevalence of Hydrologic Soil Group (HSG) Type C or C/D soils of limited
<br />infiltration capacity (Soil Map, Appendix A). A low infiltration rate of 0.25 IN/HR is assumed for the site soils. Soil
<br />borings have confirmed the character of the soils as mapped.
<br />Stormwater runoff from the overall site drains to the southeast to Lake Minnetonka. Runoff flow in the interior of the
<br />site is governed by local topography, which is generally fairly steep in the upland areas. Three wetlands have been
<br />identified and delineated on the property and are described in detail in the project wetland delineation report. Runoff
<br />from the site flows to these wetlands before discharging into Lake Minnetonka. There is an existing overland overflow
<br />channel connecting Wetland 1 (upstream) to Wetland 2 (downstream); Wetland 2 discharges at the southern property
<br />boundary, with flow proceeding southeast to Lake Minnetonka. Wetland 3 is the open water and surrounding area at
<br />the southeast corner of the property. It receives runoff from the additional connected upland on the property, and it
<br />is directly connected as part of the Lake Minnetonka open water area.
<br />The project site does not discharge to an Impaired Water within 1 mile, as defined by the State's Impaired Waters
<br />List (see map).
<br />SOILS MAP
<br />Hydrologic Soil Group -Hennepin County, Minnesota 3
<br />(24021Property)
<br />Pa
<br />aasm aamm NQ9910 aa�sm Nanela aa�ss3 aamao aassu aa�p amp
<br />qh° WV - 137 N
<br />c
<br />C/D
<br />_ c
<br />B
<br />C/D
<br />c c
<br />C/D
<br />B/D
<br />e S
<br />44° 53' 2 r N
<br />as Iwo o a aeslo
<br />Map 5rn1e: 1:3,110 ff pdnted at Aland- (11" x SS') sliest.
<br />a NnN M
<br />- 270
<br />0 1so a�o sa
<br />D
<br />Mappro]e3i-WebVil ConeromthatWGS84 Edge tla: URN Zne 15N WGS84
<br />USDA Natural Resources Web Soil Survey 7/29/2024
<br />Conservation Service National Cooperative Soil Survey Page 1 of 4
<br />CIVIL METHODS, INC.
<br />P.O. Box 28038
<br />St. Paul, MN 55128
<br />o:763.210.5713 I www.civiImethods.com
<br />EROSION & SEDIMENT CONTROL
<br />1. The contractor shall use phased construction whenever practical to minimize disturbed area at any one time. Disturbed
<br />area shall not exceed that which can be effectively inspected and maintained.
<br />2.A 50' natural buffer shall be preserved within surface waters adjacent to construction. If not feasible, redundant (double)
<br />perimeter sediment controls separated by 5.0' are required. Special Waters require 100' buffer.
<br />3.All exposed soil areas, including stockpiles, must be stabilized as soon as possible to limit soil erosion but in no case
<br />later than 14 days after the construction activity in that portion of the site has temporarily or permanently ceased.
<br />4.The following shall be installed within 24 hours of connection to surface water or property edge:
<br />4.1.Energy dissipation (rprap) at all outlet aprons
<br />4.2.Stabilization of temporary or permanent drainage swales within 200' of property boundary or connection to surface
<br />water (e.g., storm sewer inlet, drainage swale, etc.)
<br />5.A vehicle tracking BMP must be installed at the site entrance where haul vehicles are entering and exiting the site,
<br />including: rock pad, slash mulch, wash rack, etc. Streets must be swept within 24 hours of discovery of offsite
<br />tracking.
<br />6.Temporary stockpiles must have silt fence or other applicable sediment control device around the base of the pile.
<br />7.The Contractor shall be responsible to control sediment -laden surface water from leaving site. All mobilized sediment
<br />that has left the construction zone shall be collected by the contractor and properly disposed of at no additional cost
<br />to the owner.
<br />8.Any fines levied due to inadequate erosion or sediment control practices, sediment discharging from the site, etc., shall
<br />be the responsibility of the Contractor.
<br />9.Inlets shall be protected from sediment at all times, with appropriate protection installed for each phase of development.
<br />10. Infiltration / filtration basins shall not be excavated to final grade until contributing drainage area has been fully
<br />stabilized, unless rigorous measures are incorporated to keep sediment from draining to the basins (16.4).
<br />11. When excavating to within 3' of final grade of infiltration / filtration system, areas shall be staked to ensure vehicles
<br />and equipment do not compact the soil.
<br />12. Adjacent roads must be inspected and kept clear of sediment; roads to be swept within 24 hours of tracked sediment
<br />discovery.
<br />13. Additional temporary BMPs may be required to reduce the potential for sediment transport during construction. If
<br />deemed necessary by onsite personnel, Engineer or Owner shall be contacted immediately for approval or guidance, if
<br />available. Otherwise best judgment shall be used to provide rapid stabilization or sediment controls as necessary to
<br />minimize potential pollutant discharge.
<br />CONSTRUCTION IMPLEMENTATION SCHEDULE & PHASING
<br />1.Install perimeter silt fence / sediment logs, and construction entrance as shown prior to site disturbance.
<br />2.Complete soil stripping and rough grading of site.
<br />3.Install bioretention areas and outlet means.
<br />4.lnstall pavement and curbing as indicated.
<br />5.Replace topsoil and establish vegetative cover.
<br />6.Complete site restoration and final stabilization measures (remove temporary controls after construction acitivity has
<br />ceased and vegetation is established).
<br />7.Submit Notice of Termination (NOT) to MPCA within 30 days.
<br />DEWATERING & BASIN DRAINING
<br />1. Dewatering water, if necessary, must be discharged to a sediment control device (e.g., sediment basin or trap, filter
<br />bag, etc.) to prevent sediment -laden water with visual turbidity from discharging downstream. To the extent feasible, use
<br />well -vegetated upland areas of the site to infiltrate dewatering water before discharge. Contractor must visually check
<br />and photograph the discharge at the beginning and at least once every 24 hours of operation.
<br />2.If nuisance conditions result from the discharge (e.g., cloudy or opaque water, oil film, erosion, etc.), Contractor must
<br />cease dewatering and correct the situation immediately.
<br />3.If discharge water contains oil or grease, an oil -water separation or filtration device shall be used prior to discharge.
<br />4.Use appropriate energy dissipation measures on all discharges to prevent erosion at discharge outlet. Discharge must
<br />not cause nuisance or erosive conditions to downstream properties or receiving channels. Excessive inundation of
<br />downstream wetlands is not permitted (if applicable).
<br />5.If filters with backwash water are used, all backwash water must be hauled offsite for disposal, returned to the
<br />beginning of the treatment process, or incorporated into the site in a manner not causing erosion.
<br />DOWNSTREAM SURFACE WATERS AND WETLANDS
<br />00
<br />-,THE ENTIRE --
<br />SITE DRAINS
<br />TO LAKES - ,;� f
<br />MINNETONKA �!
<br />NORTH ARM,
<br />J
<br />WHICH DOES fi.
<br />n
<br />,I NOT HAVE ANY
<br />CONSTRUCTION
<br />RELATED
<br />IMPAIRMENTS. ul
<br />STUBBS BAY a1
<br />AND FOREST
<br />LAKE (BOTH
<br />"IMPAIRED) ARE
<br />WITHIN 1.0
<br />MILE BUT THE
<br />PROJECT SITE
<br />DOES NOT(,I
<br />DISCHARGE TO
<br />THEM.��
<br />I HEREBY CERTIFY THAT THIS PLAN, SPECIFICATION, OR REPORT WAS PREPARED
<br />BY ME OR UNDER MY DIRECT SUPERVISION AND THAT I AM A DULY LICENSED
<br />PROFESSIONAL ENGINEER UNDER THE LAWS OF THE STATE OF MINNESOTA.
<br />KENT E. BRANDER
<br />DATE: 03-04-2025
<br />LiC. NO.: 44578
<br />i \"S491
<br />r.�
<br />17�
<br />DESIGNED: KEB
<br />DRAWN: KEB
<br />CHECKED: DMP
<br />EROSION & SEDIMENT CONTROL QUANTITIES
<br />0-7
<br />PROJECT
<br />SITE
<br />�-
<br />!
<br />'ly
<br />_
<br />_-
<br />0
<br />LakeGl¢ssen
<br />-I \
<br />3 M j14 u%
<br />/)I
<br />PRIMARY
<br />DISCHARGE
<br />LOCATION `:.4• >`
<br />Stubbs Bay
<br />s`- o Alaxwell Bayt
<br />1 Lair ,�
<br />r�
<br />N
<br />0 3000 6000
<br />Feet
<br />DATE / REVISION:
<br />01-06-2025 Permit Submittal Set. NOT FOR CONSTRUCTION
<br />01-18-2025 Adjusted Lot Lines per Clty Comments. NOT FOR CONSTRUCTION
<br />03-04-2025 Added Cul-de-sac at Entry Turn Per City Comments. NOT FOR CONSTRUCTION
<br />INSPECTIONS & MAINTENANCE
<br />1. The contractor must routinely inspect the construction site and areas adjacent to the project once every 7 days during
<br />construction, and within 24 hrs of receiving more than Y2" of rain in 24 hrs. Rainfall amounts must be measured by
<br />a properly installed rain gage onsite, or from a weather station within 1 mile of the project, or from a weather
<br />reporting system with site specific radar rainfall summaries (1 1.1 1).
<br />2. All inspections and rainfalls > 2" must be recorded and retained onsite with the SWPPP. Inspections shall include:
<br />date/time, name of individual, date & amount of rainfall, findings, corrective actions, observed
<br />discharge/location/description, any proposed SWPPP amendments.
<br />3. Inspections may be suspended when work is stopped due to frozen conditions. The Contractor's inspector must resume
<br />inspections within 24 hours after runoff occurs at the site or prior to resuming construction, whichever comes first.
<br />4. Silt fence (or related perimeter control device) must be maintained when accumulated sediment reaches 2 the height of
<br />the device, or if device becomes ineffective (by the end of the next business day following discovery).
<br />5. Permanent and temporary sediment basins, if applicable, shall be drained and cleaned when sediment depth reaches Y2
<br />of original storage volume; complete within 72 hrs of discovery. Must be cleaned prior to project completion.
<br />6. Non-functional BMPs must be repaired or replaced by the end of the next business day following discovery.
<br />7. Inspect downstream ditch / drainage system for signs of erosion or sediment buildup during each inspection; stabilize
<br />within 7 days.
<br />8. Contractor shall inspect and photograph dewatering discharges at the beginning and every 24 hours during operation.
<br />9.Inspect vehicle exit locations and adjacent streets; remove sediment from surfaces within 1 day.
<br />POLLUTION PREVENTION
<br />1. All solid waste generated at the site must be disposed of in accordance with all applicable federal and state
<br />regulations.
<br />2. All hazardous materials must be properly stored/contained to prevent spills or leaks; materials must be properly
<br />disposed of perapplicable regulations, including Minn. Rule Ch. 7045. Restricted access storage areas must be provided
<br />to prevent vandalism.
<br />3. Vehicle or equipment washing must be confined to a defined area (minimum of 100' from pond or drainage ditch);
<br />runoff containing any hazardous materials must be collected and properly disposed of. Defined area must be delineated
<br />with heavy-duty silt fence (incidental); no engine degreasing is allowed on -site.
<br />4. Pesticides, herbicides, insecticides, fertilizers, treatment chemicals, and landscape materials must be under cover to
<br />prevent pollutant discharge, or protected by similar means to minimize potential contact with stormwater.
<br />5. Concrete and other washout waste must be effectively contained - solid and liquid washout waste must not contact
<br />ground and must be disposed of properly in compliance with MPCA rules. A sign must be installed at washout area
<br />requiring personnel to utilize the proper facilities for disposal of concrete and other wastes.
<br />6. The contractor is solely responsible for monitoring air pollution and ensuring that it does not exceed levels set by any
<br />agency or LGU. This includes dust created by work performed at the site; air pollution and dust control measures are
<br />incidental to the contract. The engineer may require additional dust control measures to be implemented, as
<br />necessary.
<br />7. Adequate temporary restroom facilities shall be present onsite in a stable and secure location during construction
<br />operations, and shall be maintained in an adequate functioning condition.
<br />FINAL STABILIZATION & NOTICE OF TERMINATION (NOT)
<br />1. The Contractor must ensure final site stabilization meets the Permit requirements, and submit the NOT within 30 days.
<br />2. Final stabilization includes uniform perennial vegetative cover of at least 70% of the expected final growth density over
<br />the entire pervious surface area, or other equivalent cover to prevent soil erosion.
<br />3. All temporary synthetic and structural BMPs must be removed as part of final stabilization.
<br />4. Ground or aerial photographs shall be taken and submitted with the NOT, confirming final stabilization measures.
<br />SWPPP UPDATES & RECORD RETENTION
<br />1. The SWPPP, all revisions to it, and inspection & maintenance records are the responsibility of the Contractor and must
<br />remain at the site during construction hours. The materials may be kept in a field office, onsite vehicle, or "SWPPP
<br />Mailbox", or be otherwise electronically available on -site.
<br />2. This SWPPP shall be updated within 7 days to include additional or modified designs when there is a change in design
<br />having significant effect on the discharge of pollutants to surface waters or groundwater.
<br />3. Training documentation shall be provided by Contractor as outlined below and required.
<br />4. The SWPPP, project permits, inspection/maintenance logs, stormwater maintenance agreements, and stormwater
<br />management design calculations must be retained for 3 years after submittal of permit NOT. Contractor shall provide
<br />Owner or Engineer copies of inspection and maintenance logs prior to final payment.
<br />TRAINING REQUIREMENTS
<br />1. The permittees must comply with the training requirements as outlined in Section 21 of the Permit. The Contractor
<br />shall have a trained individual performing BMP installations and inspections, as required.
<br />2. Training table (below) to be completed prior to construction, as appropriate.
<br />RESPONSIBLE PARTIES & TRAINING SUMMARY
<br />TRAINING
<br />COMPANY
<br />CONTACT
<br />PHONE
<br />DATE
<br />COURSE / ENTITY
<br />CONTENT
<br />OWNER:
<br />NA
<br />NA
<br />NA
<br />SWPPP PREPARER:
<br />CIVIL METHODS, INC.
<br />KENT BRANDER, PE
<br />763.210.5713
<br />1/24/2022
<br />UNIVERSITY OF MN
<br />DESIGN OF CONSTR.
<br />SWPPPS
<br />GENERAL CONTRACTOR
<br />/ INSPECTOR:
<br />EROSION & SEDIMENT
<br />CONTROL INSTALLER:
<br />PERMANENT BMP
<br />OPERATOR /
<br />NA
<br />NA
<br />NA
<br />MAINTAINER:
<br />PROJECT: IDYLLVALE SHORES
<br />PROD. LOCATION: 215 NORTH ARM LN, ORONO, MN 55364
<br />PROJ.OWNER: BRADLEY J PASS
<br />SWPPP NARRATIVE
<br />SHEET NO:
<br />C6021
<br />295
<br />
|