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HomeMy WebLinkAbout2018-04-10 MSCWMO Review 4 5 5 H A Y W A R D A V E . N O A K D A L E , M I N N E S T O A 5 5 128 P h o n e 6 5 1 . 2 7 5 . 1 1 3 6 x 2 2 f a x 6 5 1 . 2 7 5 . 1 2 5 4 w w w . m s c w m o . o r g MID DLE ST. CROIX WATERSHED MANAGEMENT ORGANIZATION M i d d l e S t . C r o i x W a t e r s h e d M a n a g e m e n t O r g a n i z a t i o n M e m b e r C o m m u n i t i e s Afton, Bayport, Baytown, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater, & W est Lakeland April 10, 2018 Eric Johnson, Administrator City of Oak Park Heights PO Box 2007 Oak Park Heights, MN 55082 RE: Palmer Station, Oak Park Heights Dear Mr. Johnson, The Middle St. Croix Watershed Management Organization (MSCWMO) received required submittal items for the proposed Palmer Station project, located within MSCWMO boundaries and in the City of Oak Park Heights. The proposed project qualifies for full review under the MSCWMO 2015 MSCWMO Watershed Management Plan (WMP). The MSCWMO Board required revisions and resubmission of the project at their regular board meeting on April 12, 2018. Please make the following revisions and resubmit. 1) Submit dedication or easement of the property which are adjacent to the facility and which lie below the 100 year flood level. 2) Submit a maintenance agreement in a format approved by the City. 3) Identify training requirements for the person responsible for erosion and sediment control inspections. 4) Identify inlet protection for stormwater inlets. 5) Add redundant sediment controls required around wetland #1. 6) Expand non impacted buffer areas for wetland #1 to compensate for the required buffer averaging. 7) Label proposed buffer areasl 8) Modify the following building lot elevations: Building lot # 8 must increase elevation by .1 ft. Building lot #13 needs LFO to be 955.9. 9) Revised MIDS calculator utilizing the correct practices and ponding depth restrictions for the biofiltration basin to demonstrate compliance with MIDS FTO #2. 10) Identify as built survey and method to demonstrate infiltration or filtration basin is functioning. 11) Include the following construction standards for the biofiltration basin: a. Installation of volume control facilities must occur in dry soil conditions. Excavation, soil placement and rapid stabilization of perimeter slopes must be accomplished prior to the next precipitation event. b. Excavation shall be performed by an excavator with a toothed bucket. Use excavator bucket to place materials. Construction equipment shall not be allowed into the basin. c. Prior to the release of any remaining fee or security, the permit holder must provide documentation that constructed volume control facilities perform as designed. 12) Identify the location of the 8.0” maintenance access to the South Filtration Basin on the grading plans. The enclosed checklist contains detailed information on project review and the policies and performance standards of the WMP. Feel free to contact me at 651-330-8220 x22 or misensee@mnwcd.org if you have any questions regarding these comments. Sincerely, September 4, 2008 Page 2 of 2 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakela nd Township Mike Isensee MSCWMO Administrator Enclosure 4 5 5 H A Y W A R D A V E . N . O A K D A L E , M I N N E S T O A 5 5 1 2 8 P h o n e 6 5 1 . 3 3 0 . 8 2 2 0 x 2 2 f a x 6 5 1 . 3 3 0 . 7 7 4 7 w w w . m s c w m o . o r g MIDDLE ST. CROIX WATERSHED MANAGEMENT ORGANIZATION M i d d l e S t . C r o i x W a t e r s h e d M a n a g e m e n t O r g a n i z a t i o n M e m b e r C o m m u n i t i e s Afton, Bayport, Baytown, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater, & W est Lakeland PROJECT REVIEW MSCWMO Project Review ID: 18-005 Project Name: Palmer Station Applicant: Mark Guenther, Creative Homes Construction Investment LLC, 707 Commerce Drive, Suite 410, Minneapolis, MN 55401 Purpose: 13 Lot Residential Subdivision Location: Oak Park Heights Review date: 3/26/2018 Recommendation: Revise and resubmit. Revisions required: 1) Submit dedication or easement of the property which are adjacent to the facility and which lie below the 100 year flood level 2) Submit a maintenance agreement in a format approved by the City. 3) Identify training requirements for the person responsible for erosion and sediment control inspections. 4) Identify inlet protection for stormwater inlets 5) Add redundant sediment controls required around wetland #1. 6) Expand non impacted buffer areas for wetland #1 to compensate for the required buffer averaging. 7) Label proposed buffer areas 8) Modify the following building lot elevations: Building lot # 8 must increase elevation by .1 ft. Building lot #13 needs LFO to be 955.9. 9) Revised MIDS calculator utilizing the correct practices and ponding depth restrictions for the biofiltration basin to demonstrate compliance with MIDS FTO #2. 10) Identify as built survey and method to demonstrate infiltration or filtration basin is functioning. 11) Include the following construction standards for the biofiltration basin: a. Installation of volume control facilities must occur in dry soil conditions. Excavation, soil placement and rapid stabilization of perimeter slopes must be accomplished prior to the next precipitation event. b. Excavation shall be performed by an excavator with a toothed bucket. Use excavator bucket to place materials. Construction equipment shall not be allowed into the basin. c. Prior to the release of any remaining fee or security, the permit holder must provide documentation that constructed volume control facilities perform as designed. 12) Identify the location of the 8.0” maintenance access to the South Filtration Basin on the grading plans. Applicability: Any project undertaking grading, filling, or other land alteration activities that involve movement of 100 cubic yards of earth or removal of vegetation on greater than 10,000 square feet of land April 10, 2018 Page 2 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township Any project that creates or fully reconstructs 6,000 square feet or more of impervious surface All major subdivisions or minor subdivisions that are part of a common plan of development. Major subdivisions are defined as subdivisions with 4 or more lots. Any project with wetland impacts Any project with grading within public waters Any project with grading within buffers Any project with grading within 40-feet of the bluff line Development projects that impact 2 or more of the member communities New or redevelopment projects within the St. Croix Riverway that require a building permit that adds five hundred (500) square feet or more of additional impervious surface Any project requiring a variance from the current local impervious surface zoning requirements for the property Any land development activity, regardless of size, that the City determines is likely to cause an adverse impact to an environmentally sensitive area or other property, or may violate any other erosion and sediment control standard set by the member community. SUBMITTAL ITEMS: Electronic submittals are highly encouraged A completed and signed project review application form and review fee Grading Plan/Mapping Exhibits a. Property lines and delineation of lands under ownership of the applicant. b. Delineation of existing on-site wetlands, shoreland and/or floodplain areas (including any buffers). c. Ordinary High Water (OHW) elevations and datum, as determined by the MDNR (if applicable). d. Existing and proposed site contour elevations related to NAVD 1988 datum (preferred) or NGVD, 1929. Datum must be noted on exhibits. e. Drainage easements covering land adjacent to ponding areas, wetlands, and waterways up to their 100-year flood levels and covering all ditches and storm sewers. Access easements to these drainage easements and to other stormwater management facilities shall also be shown. f. Minimum building elevation for each lot. g. Identification of downstream water body. April 10, 2018 Page 3 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township Permanent Stormwater Management System in compliance with the requirements of the NPDES SDS Construction Stormwater Permit and MSCWMO Performance Standards. a. Impervious areas (Pre- and Post-Construction). b. Construction plans and specifications for all proposed stormwater management facilities. c. Location(s) of past, current or future onsite well and septic systems (if applicable). Other exhibits required to show conformance to these Performance Standards A Stormwater Pollution Prevention Plan in compliance with the requirements of the NPDES SDS Construction Stormwater Permit Grading Plan/Mapping Exhibits: a. Delineation of the subwatersheds contributing runoff from off-site, proposed and existing on-site subwatersheds, and flow directions/patterns. b. Location, alignment, and elevation of proposed and existing stormwater facilities. c. Existing and proposed normal water elevations and the critical (the highest) water level produced from the 100-year 24-hour storms. d. Location of the 100-year flood elevation, natural overflow elevation, and lowest floor elevations. Hydrologic/Hydraulic Design Exhibits: a. All hydrologic and hydraulic computations completed to design the proposed stormwater management facilities shall be submitted. Model summaries must be submitted. The summaries shall include a map that corresponds to the drainage areas in the model and all other information used to develop the model. b. A table (or tables) must be submitted showing the following: i. A listing of all points where runoff leaves the site and the existing and proposed stormwater runoff rates and volumes. ii. A listing of the normal water levels under existing and proposed conditions and the water levels produced from the storm and runoff events listed above for all on-site wetlands, ponds, depressions, lakes, streams, and creeks. Dedications or easements for the portions of the property which are adjacent to the facility and which lie below the 100 year flood level. For sites within public right-of-way, no easement is required. A proposed maintenance agreement, which may be in the format of Appendix K, or other form approved by the city. HISTORY & CONSIDERATIONS: SPECIAL OR IMPAIRED WATER April 10, 2018 Page 4 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township NA This site drains to, and is within one mile of special or impaired water and complies with enhanced protections. a. Scenic or Recreational river C.1., C.2., C.3. b. Scientific and Natural area C.1., C.2., C.3. c. Waterbody with a TMDL C.1., C.2. C.1. Stabilization initiated immediately and all soils protected in seven days/provide temp basin for five acres draining to common location. C.2. Treat water quality volume of one inch of runoff by retaining on site unless not feasible due to site conditions (See Part III.D.1. design requirements). C.3. Maintain buffer zone of 100 linear feet from Special Water. EROSION AND SEDIMENT CONTROL [A checked box indicates compliance] A Stormwater Pollution Prevention Plan (SWPPP) that meets the National Pollutant Discharge Elimination System (NPDES) requirements. Narrative Identify the person knowledgeable and experienced who will oversee the implementation of the SWPPP; the installation, inspection, and maintenance of the BMPs. a. Identifies the person who will oversee the BMP inspection and maintenance. b. Identify the training requirements are satisfied. c. Inspections performed once every 7 days. d. Inspections performed within 24 hours of a rain event greater than 0.5 in/24 hours. e. Inspection and Maintenance records include: i. Date and time of inspection. ii. Name of person(s) conducting inspections. iii. Finding of inspections, including the specific location where corrective actions are needed. iv. Corrective actions taken (including dates, times, and party completing maintenance activities). v. Date and amount of rainfall events greater than 0.5 in/24 hours. vi. Rainfall amounts must be obtained by a properly maintained rain gauge installed onsite, or by a weather station that is within one mile or by a weather reporting system. vii. Requirements to observe, describe, and photograph any discharge that may be occurring during the inspection. viii. All discovered nonfunctional BMPs must be repaired, replaced, or supplemented with functional BMPs within 24 hours after discovery, or as soon as field conditions allow. Describes procedures to amend the SWPPP and establish additional temporary ESC BMPs as necessary for site conditions. April 10, 2018 Page 5 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township Describes the installation timing for all Erosion Sediment Control (ESC) Best Management Practices (BMPs). Describes final stabilization methods for all exposed areas. Methods used to minimize soil compaction and preserve topsoil must be described. Describes dewatering technique to prevent nuisance conditions, erosion, or inundation of wetlands? NA Identifies any specific chemicals and the chemical treatment systems that may be used for enhancing the sedimentation process on the site, and how compliance will be achieved with the permit requirements. Describes pollution prevention management measures a. Storage, handling, and disposal of construction products, materials, and wastes. b. Fueling and maintenance of equipment or vehicles; spill prevention and response. c. Vehicle and equipment washing. d. No engine degreasing allowed on site. e. Containment of Concrete and other washout waste. f. Portable toilets are positioned so that they are secure. Plan sheets NA Temporary Sediment Basins required (10 acres draining to common location or 5 acres App. A) Basin design meets the following criteria: a. Adequately sized – 2-year, 24-hour storm, minimum 1,800 feet/acre; or no calculative minimum 3,600ft3/acre. b. Designed to prevent short circuiting. c. Outlets designed to remove floating debris. d. Outlets designed to allow complete drawdown. e. Outlets designed to withdraw water from the surface f. Outlets have energy dissipation. g. Have a stabilized emergency spillway. h. Situated outside of surface waters and any natural buffers. Locations and types of all temporary and permanent Erosion Control BMPs. a. Exposed soils have erosion protection/cover initiated immediately and finished within 7 days. b. Wetted perimeters of ditches stabilized within 200 feet of surface water within 24 hours. c. Pipe outlets have energy dissipation within 24 hours of connecting. April 10, 2018 Page 6 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township Locations and types of all temporary and permanent Sediment Control BMPs. a. Sediment control practices established on down gradient perimeters and upgradient of any buffer zones. b. All inlets are protected. Proposed inlets draining to the fore-bay require protection. c. Stockpiles have sediment control and placed in areas away from surface waters or natural buffers. d. Construction site entrances minimize street tracking e. Plans minimize soil compaction and, unless infeasible to preserve topsoil. f. 50 foot natural buffers preserved or (if not feasible) provide redundant sediment controls when a surface water is located within 50 feet of the project’s earth disturbances and drains to the surface water. Redundant sediment controls required around wetland #1. Tabulated quantities of all erosion prevention and sediment control BMPs. Stormwater flow directions and surface water divides for all pre- and post-construction drainage areas. Locations of areas not to be disturbed (buffer zones). Label buffer areas. NA Location of areas where construction will be phased to minimize duration of exposed soil areas. NA Blufflines are protected from construction activities in urban (40 foot buffer) areas and rural areas (100-foot buffer). N/A LAKE, STREAM AND WETLAND BUFFERS A buffer zone of unmowed natural vegetation is maintained or created upslope of all water bodies (wetlands, streams, lakes). Expand non impacted buffer areas for wetland #1 to compensate for the required buffer averaging. NA A 50 foot natural buffer or (if a buffer is infeasible) provide redundant sediment controls when a surface water is located within 50 feet of the project’s earth disturbances and stormwater flows to the surface water. NA If adjacent to a Special or Impaired Water an undisturbed buffer zone of not less than 100 linear feet from the special water is maintained both during construction and as a permanent feature post construction. STORMWATER MANAGEMENT [A checked box indicates compliance] Water quality treatment is provided prior to direct discharge of stormwater to wetlands and all other water bodies. Rate and Flood Control Standards The peak rate of stormwater runoff from a newly developed or redeveloped site shall not exceed the 2-, 10-, and 100-year 24-hour storms with respective 2.8, 4.2, and 7.3-inch rainfall depths with MSCWMO approved time distribution based on Atlas 14 for existing and proposed conditions. The runoff curve number for existing agriculture areas shall be less than or equal to the developed condition curve number. The newly developed or redeveloped peak rate shall not exceed the existing peak rate of runoff for all critical duration events, up to and April 10, 2018 Page 7 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township including the 100-year return frequency storm event for all points where discharges leave a site during all phases of development. Predevelopment conditions assume “good hydrologic conditions” for appropriate land covers as identified in TR−55 or an equivalent methodology. Runoff curve numbers have been increased where predevelopment land cover is cropland: Hydrologic Soil Group A: Runoff Curve Number 56 Hydrologic Soil Group B: Runoff Curve Number 70 Hydrologic Soil Group C: Runoff Curve Number 79 Hydrologic Soil Group D: Runoff Curve Number 83 Computer modeling analyses includes secondary overflows for events exceeding the storm sewer systems level-of- service up through the critical 100-year event. NA In sub-areas of a landlocked watershed, the proposed project does not increase the predevelopment volume or rate of discharge from the sub-area for the 10-year return period event. Flowage easements up to the 100-yr flood level have been secured for stormwater management facilities (such as ditches and storm sewers). Lowest floor elevations of structures built adjacent to stormwater management features and other water bodies are a minimum of two feet above the 100-year flood elevation and a minimum of two feet above the natural overflow of landlocked basins. Building lot # 8 must increase elevation by .1 ft. Building lot #13 needs LFO to be 955.9 Volume Control Standards Calculations/computer model results indicate stormwater volume is controlled for new development and redevelopment requirements per the MSCWMO Design Standards. 1. New Nonlinear Development 1.1” * new impervious surfaces 2. Reconstruction/Redevelopment Projects 1.1” * reconstructed impervious surfaces 3. Linear Projects 0.55” * new and/or fully reconstructed impervious surface and 1.1” from net increase in impervious area 4. Sites with Restrictions- flexible treatment options documented due to the site being located within the City of Oak Park Heights Well Head Protection Zone. Volume Retention Required (cu. ft.) Volume Retention Provided (cu. ft.) 103,600 * 0.55”= 4,748 and 75% TP Reduction per MIDS Calculator Total Required 4,748 cu. ft. and 75% TP Reduction per MIDS. BMP Volume BMP #1 6,417 cu. ft. BMP #2 8,107 cu. ft. Total Proposed 14,524 cu.ft. April 10, 2018 Page 8 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township Flexible Treatment Options (when applicable) Applicant demonstrated qualifying restrictions as defined in Section 7.2.2 (4) of the 2015 MSCWMO Watershed Management Plan that prohibits the infiltration of the entire required volume. MIDS calculator submission removes 60% of the annual total phosphorous. When used correctly, the MIDS calculator indicates 60% TP load reduction is not achieved. Infiltration/Filtration Design Standards Proposed stormwater management features meet or exceed NPDES General Construction Permit requirements are designed in conformance with the most recent edition of the State of Minnesota Stormwater Manual. The following condition exists that prohibits infiltration of stormwater on the site Areas of Hydrologic Soil Group D (clay) soils Minimum setbacks from the Minnesota Department of Health for infiltration practices are met Setback Minimum Distance (ft) Property line 10 Building foundation* 10 Private well 35 Public water supply well 50 Septic system tank/leach field 35 *Minimum with slopes directed away from the building Pretreatment devices(s) remove at least 50% of sediment loads. If downstream from a potential hot spot, a skimmer is in place to facilitate cleanup. Water quality volume will be discharged through infiltration or filtration media in 48 hours or less. a. For bioretention (biofiltration and bioinfiltration) volume control management facilities above ground with vegetation the period of inundation shall be calculated using the maximum water depth below the surface discharge elevation and the soil infiltration rate or the MIDS calculator. b. For infiltration basin volume control management facilities the period of inundation shall be calculated using the maximum water depth below the surface discharge elevation and the soil infiltration rate. Appropriate soil borings have been conducted that meet the minimum standards. April 10, 2018 Page 9 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township a. A minimum of one boring was conducted at the location of the infiltration facility for facilities up to 1,000 ft²; between 1,000 and 5,000 ft², two borings, between 5,000 and 10,000 ft², three borings and greater than 10,000 ft² 4 borings plus an additional boring for every 2,500 ft² beyond 12,500 ft² b. Soil borings extend a minimum of five feet below the bottom of the infiltration practice. If fractured bedrock is suspected, the soil boring goes to a depth of at least ten feet below the proposed bottom of the volume control facility. c. A minimum of three feet of separation to the seasonal water table and/or bedrock. d. Identify unified soil classification. NA The least permeable soils horizon identified in the soil boring dictated the infiltration rate. Filtration makes this NA Additional flows are bypassed and are routed through stabilized discharge points. Filtration basin demonstrates a basin draw down between 24 hours and 48 hours. Ponding depth of the biofiltration basins exceed 1.5’ maximum ponding depth standards. Maximum ponding depth of filter is 4’ – condition met N/A Filtration system Iron Enhanced Sand Filter is sized to bind soluble phosphorous removal for 30 year functional life of the system using the published value of 17lbs.phosphorous removal per 20 yards of 5% by weight iron filings to 95% sand. Identify as built survey and method to demonstrate infiltration or filtration basin is functioning. Construction plans provide adequate construction guidance to prevent clogging or compaction and demonstrate performance. d. Excavation within 2.0 feet of final grade for infiltration/filtration systems is prohibited until contributing drainage areas are constructed and fully stabilized. e. Rigorous sediment and erosion controls planned to divert runoff away from the system. f. Installation of volume control facilities must occur in dry soil conditions. Excavation, soil placement and rapid stabilization of perimeter slopes must be accomplished prior to the next precipitation event. g. Excavation shall be performed by an excavator with a toothed bucket. Use excavator bucket to place materials. Construction equipment shall not be allowed into the basin. h. Prior to the release of any remaining fee or security, the permit holder must provide documentation that constructed volume control facilities perform as designed. There is a way to visually verify the system is operating as designed. A minimum 8.0’ maintenance access is provided to all stormwater facilities. Clarify the location of the maintenance access to the South Filtration Basin on the grading plans. WETLAND PERFORMANCE STANDARDS Direct discharge of stormwater to wetlands and all other water bodies without water quality treatment is prohibited. April 10, 2018 Page 10 of 10 Middle St. Croix Watershed Management Organization MEMBER COMMUNITIES: Afton, Bayport, Baytown Township, Lakeland, Lakeland Shores, Lake St. Croix Beach, Oak Park Heights, St. Mary’s Point, Stillwater and West Lakeland Township Any potential changes to the hydrology of the wetland (i.e. changes to the outlet elevation or contributing drainage area) must be reviewed to evaluate the impact of both the existing and proposed wetland conditions and approved by the MSCWMO. Land-altering activities shall not increase the bounce in water level or duration of inundation from a 2.0-inch 24- hour storm for any downstream wetland beyond the limit specified in Table 7.2 for the individual wetland susceptibility class. Notes/Conditions: Filters shall have a liner.