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The Park Aproval Letter Response 5-24-19 MEMORANDUM TO: Kate Aanenson, Community Development Director FROM: Paul Cherne, Pioneer Engineering CC: Joe Jablonski, Lennar DATE: February 28, 2019 RE: The Park Subdivision Review Parks & Recreation 1. Dedication of 100+/- acres of wooded open spaces and wetlands in the eastern half of the property to the City of Chanhassen for parkland in exchange for a housing density transfer and fulfillment of a nine +/- acre parkland dedication requirement. 2. Acknowledgement that the dedicated land may be developed at the city's discretion as parkland for public use and may include, but is not limited to trails, boardwalks, bridges, structures, and signage. 3. The planning, engineering, grading, and placement of aggregate and bituminous base for construction of a 10-foot wide bituminous east/west trail connection between Galpin Boulevard and a location east of Street “D”, and a 10-foot wide bituminous trail adjacent to Galpin Boulevard between Street “E” and Street “A”. 4. All trails shall meet all city standards for trail construction. 5. The east/west trail shall maintain a minimum 10-foot setback from outside edges of trail to private property and be designed to minimize encroachment of wetland buffers. 6. The east/west trail crossing of Street “A” shall be relocated from a midblock crossing as shown to the intersection of Street “A” and Street “D”. 7. The east/west trail be designed and constructed so as not to require retaining walls. 8. The entirety of the east/west trail and associated buffers shall be constructed within the dedicated public outlots. 9. The planning, engineering and construction of 10-foot wide bituminous trails connecting both Street “Z” and Topaz Drive/Ridge Lane to the planned trail at the western edge of Lake Lucy including trail easements. 10. A parking lot shall be constructed for access to the park with a minimum of eight stalls. All the conditions of the Park Department comments will be met ( see revised preliminary plans). The trail connection from Topaz Street to the trail extension near Lake Lucy will not meet ADA standards due to steep slopes. The trail along Galpin Boulevard will need to be constructed in conjunction with the Galpin Boulevard improvement project. Planning 1. All 191 acres must be included in the PUD. 2. All lots and homes must be developed consistent with the standards in the Compliance Table. A revised compliance table has been prepared along with a map. Engineering 1. Any requirements set by the MCES to work within the MCES’s sewer and utility easement shall be addressed by the applicant. Noted 2. An executed agreement between the developer and the MCES allowing work within the MCES’s easement shall be provided to the city prior to the issuance of grading permits. Agreements will be obtained prior to commencing work in the easement 3. The width of the public right-of-ways shall be called out on the final plat prior to acceptance and recording, this includes radii cul-de-sac bulbs. Shown on the submitted final plat 4. Thirty-foot (30-foot) wide drainage and utility easements, for the purpose of accessing utilities and basins, shall be provided between but not limited to Lots 120 and 121 abutting Street “Z” prior to acceptance and recording. Shown on the preliminary and final plat 5. Right-of-way dedication in conformance with the Carver County Development/Access Review Comments, subject to review and approval by the county and city prior to acceptance and recording of the final plat. Shown on the preliminary and final plat 6. Ongoing coordination with the county and city regarding future improvements to Galpin Boulevard. Also see Condition 25. Noted 7. The developer shall locate on the existing condition survey all existing wells and septic fields. All wells and septic systems that were discovered are shown on the plans. 8. The developer shall abandon all existing wells and septic fields in accordance with all federal, state, and local regulatory agency standards, and obtain all necessary permits for said abandonments. These conditions will be met. 9. Prior to commencement of abandonment activities, a copy of all required permits from the appropriate regulatory agencies shall be provided to the city. These conditions will be met. 10. Provide an updated existing condition survey that illustrates the MCES sanitary and utility easements on parcels 250100400 and 257580040. We will need to be furnished copies of the easement agreements on these properties to provide this information. 11. The applicant shall submit a mass grading plan or a phased grading plan (as applicable) for review and approval by the city prior to issuance of grading permits. Attached is a final grading plan 12. Proposed spot elevations shall be shown on the grading plans at the center of the proposed driveway at the curb line for review prior to issuance of grading permits. The spot elevations are shown 13. Proposed spot elevations shall be shown on the grading plans at top of curb for review prior to issuance of grading permits. The spot elevations are shown 14. Drainage arrows for all EOF routes shall be included on the grading plans prior to issuance of grading permits. EOF routes are shown 15. Grading within bluff setbacks is subject to review and approval by the city prior to issuance of grading permits. Grading has been moved outside the bluff protection zone. 16. All existing buildings and structures within the city’s Well House #3 property abutting Galpin Boulevard shall be included on the grading plans. Structures have been added to the plans 17. Grading plans shall be updated to include the location and grade of the improved and relocated access driveway to Well House #3 off Galpin Boulevard. Please furnish a sketch of the proposed work 18. Grading plans shall be updated to include the location and protection methodology of the significant oak tree on the Well House #3 site. No grading is proposed on the well house property 19. The applicant shall submit revised grading plans and stormwater plans so that no stormwater runoff flows directly onto the public trail south of Lots 164-174 abutting Street “A”. Storm sewer has been added to the plan 20. An updated geotechnical report assessing slope stability immediately east of Lot 110 abutting Street “A” shall be submitted for review and approval prior to the issuance of grading permits. The described situation no longer exists on the revised plan 21. Final grading plans, including pond locations, sizing and analysis, along with right-of-way dedications off Galpin Boulevard, shall conform to the future Galpin Boulevard reconstruction project. Cross reference of grading plans, profiles, and respective cross sections are to be provided at key locations such as intersections, ponds, or other special features required by the county and city for review prior to acceptance and recording of the final plat. An exhibit has been prepared showing the street connections to the preliminary CR 117 profile. 22. All retaining walls exceeding four (4) feet in height shall have plans and details prepared by a registered engineer or landscape architect prior to issuance of building permits. No retaining was are being proposed. 23. The retaining wall south of Lots 108-111 abutting Street “A” shall be adjusted to accommodate a 1.5:1 buffer from the bottom of the proposed stormwater line to the bottom of the proposed retaining wall foundation. This wall has been eliminated 24. Grading and construction within bluff setbacks are subject to review and approval by the city prior to issuance of grading permits. Grading within the bluff protection zone has be eliminated 25. All newly constructed streets and the extension of any existing streets shall be public streets, owned and maintained by the city, after acceptance of the public improvements by the City Council. Noted 26. All newly constructed public streets shall be designed to meet the current standard specifications and detail plate for residential streets (Detail Plate #5200), unless otherwise directed by the City Engineer. Noted 27. Any and all conditions associated with the alignment and configuration of Street “Z” set by the Planning Commission or City Council shall be addressed by the applicant prior to acceptance and recording of the final plat. Noted 28. The Developer shall provide a curb cut and access easement for parcel 250100400 onto Street “Z”. Surmountable curb will be constructed on Street Z 29. A water service lateral shall be stubbed off Street “Z’s” water main for the future connection to parcel 250100400. A 1” service will be provided 30. An updated geotechnical report with additional soil borings shall be provided for review and approval prior to the commencement of construction. Addition geotechnical was performed in the pond areas 31. Sidewalks shall be extended along the cul-de-sacs located off Streets “D”, “G”, and “Z” and shall be constructed in accordance with the city’s standard specifications and detail plates for concrete sidewalks. Sidewalk has been added to the plans 32. All curb ramps shall be constructed to meet ADA standards and the city’s Detail Plates #5215- 5215D. Noted 33. Intersection improvements to provide pedestrian access at the intersection of Galpin Boulevard and Street “E” shall be constructed in accordance with MUTCD best management practices. The pedestrian crossing design will be provided with the final plans for this phase 33. A detail of the proposed street lights shall be provided prior to the issuance of building permits. Lennar will provide details 34. An enumerated list of all street lights and their proposed locations shall be provided for review and approval prior to the recording of the final plat. Street light locations are shown on the plans 35. Street lights shall be installed at all intersections and at the end of each cul-de-sac subject to review and approval of the city prior to issuance of building permits. Street light locations are shown on the plans 36. The site plan shall be updated to provide proposed street grades (centerline gradients). This information is shown on the grading plan and the street profiles 37. All newly constructed water mains shall be public water mains, owned and maintained by the city, after acceptance of the public improvements by the City Council. Noted 38. Water mains located on Streets “A”-“H” and Street “Z” shall be tied into the high-pressure zone located on Galpin Boulevard. Water main extensions on Topaz Drive and Lucy Ridge Lane shall be tied into the existing water main stubs (low-pressure zone). The connection is shown on the plans 39. The water main located on Street “Z” shall be tied into the existing stub off Ruby Lane and a gate valve near the connection point shall be installed. The gate valve shall be closed to separate the pressure zones. The connection is shown on the plans 40. The developer shall field-verify the location of all water main taps prior to the issuance of building permits and update the plans accordingly. Water services will be located after construction 41. The developer’s contractor shall schedule a preconstruction meeting with Engineering and Public Works Utilities prior to the commencement of any work to the water main installation and tapping. A precon meeting will be scheduled 42. Updated plans indicating the location of all underground utilities on the east side of Galpin Boulevard, along with plans and profiles of any utility crossings on the east side of Galpin Boulevard, shall be submitted for review and approval prior to the issuance of building permits. All utilities that were located are shown on the plans. Profiles are shown on the plans 43. An agreement that lists the conditions and required improvements for the land swap between the developer and the city regarding Lot 163 and a portion of the Well House #3 site, shall be executed and recorded prior to the acceptance and recording of the final plat. No improvements are required with the approved plans 44. All utility crossings of potable water and sanitary and/or storm mains will require 18 inches of vertical separation and 10 feet of horizontal separation. The developer shall submit construction plans with profiles and plan views of the utilities for review and approval prior to the issuance of building permits. The crossing requirements are being met. 45. All utility crossings of potable water and sanitary sewer will require that the sanitary sewer main at that crossing be constructed of PVC C900 water main material. The developer shall submit construction plans indicating material type at these locations for review and approval of the city prior to issuance of building permits. This not required by 10 States Standards, City of Chanhassen Specifications or CEAM 46. The developer shall submit construction plans indicating that pipe lengths of sanitary sewer mains are centered over potable water crossings. A note meeting the requirements of 10 States Standards, has been added. 47. Water mains shall be constructed at 7.5 feet below grade, or insulated, and constructed in conformance with the city’s standard specifications and detail plates. Shown on the plans 48. Cluster valves located around water main tees shall be installed at a minimum of 5 feet from the tees to the valves, where feasible. All valve locations and any other water main appurtenances shall be reviewed and approved by Engineering and Public Works prior to the issuance of building permits. Shown on the plans 49. All comments and conditions regarding fire appurtenances, spacing, and location set forth by the Fire Department shall be addressed by the applicant. Please provide Fire Department comments 50. All newly constructed sewer mains shall be public sewer mains, owned and maintained by the city after acceptance of the public improvements by the City Council. Noted 51. A 30-foot utility easement shall be recorded over the existing public sewer line, within Outlot A located near the south-central area of the preliminary plat, prior to acceptance of final plat. The sewer line will be within property owned by the City 52. All conditions set forth by the MCES for the direct connection and installation of an access manhole to their trunk line shall be addressed by the applicant, and all permits required for the connection and installation of the manhole shall be obtained prior to the commencement of construction. A permit will be obtained with this phase of construction 53. The applicant shall ensure the city’s sanitary sewer nomenclature is incorporated in the construction plans. Please furnish structure numbers with review of 1st addition plans 54. Profile sheets for all public utilities, including sanitary sewer, shall be required for review and approval by the city prior to issuance of building permits. See 1st Addition plans 55. PVC sanitary sewer pipes that will be constructed at a burial depth of 0-16 feet shall be constructed of pipe class SDR 35, burial depths of 16-26 feet shall be of pipe class SDR 26, and burial depths of greater than 26 feet shall be of pipe class C900. Plans conform to these requirements 56. Inverts that have a 20-inch or greater differential shall be supplied inside drops per city standards and be constructed per the city’s Detail Plate No. 2104. Plans conform to these requirements 57. No roadway connection shall be made to Topaz Drive. See revised plans Stormwater Conditions & Wetlands The 2019 SWMP Fee is $432,183.23, pending any plan revisions. This fee will be applied to the new lots of record being created. It is calculated as shown in the table below: SURFACE WATER DEVELOPMENT FEE AREA PER ACRE FEE ACRES FEE GROSS AREA $8,320 191.0465 $1,589,506.88 ROW $8,320 16.79 $(139,692.80) OUTLOTS $8,320 122.3114 $(1,017,630.85) NET AREA 51.9451 $432,183.23 Assessments Water and sewer partial hookups are due at the time of final plat. The partial hookup fees will be assessed at the rate in effect at that time. The remaining partial hookups fees are due with the building permit. Fees Based on the proposal, the following fees would be collected with the development contract: • Administration Fee: If the improvement costs are between $500,000 and $1,000,000, 2% of the improvement costs. If the improvement costs exceed $1,000,000, 2.5% of the first $1,000,000 plus 1.5% of the remainder. • Surface Water Management Fee: $432,183.23 • A portion of the water hook-up charge: $2,311/unit • A portion of the sanitary sewer hook-up charge: $691/unit • GIS fees: $25 for the plat plus $10 per parcel • Street light operating fee for one year: $300 per light Conditions of Approval 1. Wetland permitting is required due to the proximity of and proposed impacts to wetlands on site. A wetland permit application has not yet been received by the city from the applicant. Grading permits will not be issued until approved wetland permits have been received. Wetland permits are pending approval The TEP has met and approved the replacement plan 2. Wetland review will include ensuring hydrology is maintained to all wetlands to be preserved as well as review of proposed stormwater impacts. See attached stormwater management plan 3. Storm sewer sizing calculations should be provided to confirm storm sewer is sized to convey the 10-year storm event. Rational calculations have been submitted 4. An NPDES permit and accompanying Stormwater Pollution Prevention Plan (SWPPP) will be required prior to the start of construction. Lennar is preparing the SWPPP and permit application 5. An operations and maintenance plan for the proposed stormwater management system will be required prior to approval. An O and M plan will be prepared 6. Provide infiltration test results per MPCA Requirements in the location of each proposed infiltration area. Additional testing has been preformed see attached Braun report 7. All comments and conditions set forth by the Riley Purgatory Bluff Creek Watershed District shall be addressed by the applicant. A new stormwater management plans has been submitted for review. 8. Show all existing storm sewer and other water resource-related features in plans. The plans have been updated 9. Adjust and show all easements over the Metropolitan Council Environmental Services’ sanitary sewer on the preliminary and final plat. The sewer interceptor is within City owned property or on property owned by others 10. Clearly indicate what storm sewer will be private and what will be public. All public storm sewer will be required to be shown in profile view. Applicant should confirm there are no conflicts with the water main or sanitary sewer throughout the site. It is proposed that all storm sewer will be public 11. The following comments pertain to all proposed ponds that include an infiltration bench (Basins 100, 200 and 300): a. Infiltration test results will be required in the location of all proposed infiltration benches and infiltration basins. Infiltration test results have not been submitted in the location of proposed Basin 100. If filtration is to be used, the applicant will need to provide a specification for amended soils. b. The exfiltration above the piped outlet elevation should be included in the HydroCAD model and the exfiltration rate should correspond to what is presented in the infiltration test results. c. The proposed infiltration benches will be required to meet the 48-hour drawdown requirement. d. Outlets from the pond should be moved out of the permanent pond area and should be moved away from the inlet to minimize the risk of short circuiting. 12. The proposed piped outlet being modeled for Basin 400 is not shown in the plans. 13. Access routes for all proposed stormwater basins are required for maintenance purposes. Applicant should callout access locations for all proposed stormwater basins. 14. A defined riprap EOF spillway will be required for all stormwater basins per details provided on Sheet 33. Applicant should include location and elevation of all EOF spillways on the storm sewer plans. 15. The soil borings provided show that there are clay soils throughout the site. Modeling should be updated to reflect the D soils present. 16. Proposed and existing HydroCAD models should be modeling the same area. There is roughly 120 acres included in the existing conditions model that is not included in the proposed conditions model. All offsite drainage should be included in the models. 17. Existing and proposed conditions drainage area maps should be updated to show the location and boundaries of all subcatchments included in the models. 18. Time of concentrations should be calculated in HydroCAD and not directly entered to confirm accuracy. Provide supporting calculations for all directly entered times of concentrations. 19. From the drainage area maps, it appears that P-LU 2-6 (P.E. Edit) in the existing model corresponds to Pond 500P in the proposed conditions model. The modeled storage for the wetland differs between the existing and proposed conditions models but no wetland impacts are shown on Sheet 37 for this wetland. Applicant should update the models so that they have the same storage modeled for the wetland. a. There is a proposed piped outlet from this wetland that is over four feet lower than the current natural spillway outlet. The applicant will be required to show that this does not change the hydrology of the existing wetland as part of the wetland permit requirements. 20. There are numerous inconsistencies between what is shown in the plans on Sheet 35 for the outlets of the stormwater basins and what is being modeled in HydroCAD and P8. Applicant will need to update the models so that they are representative of what is being shown in the plans. 21. The same total area should be modeled in P8 as in HydroCAD. 22. The model should be run for at least 50 years and should include the most recent precipitation data included in the precipitation file to get accurate removal efficiencies. 23. The modeling of the proposed stormwater ponds with filtration benches is incorrect and is overestimating the removal efficiencies of the basins. The applicant should update the model for the stormwater basins in the following way: a. The design infiltration rate should be added to the flood pool section of the stormwater pond devices where applicable. This will model infiltration above the outlet elevation. The design infiltration rate should match what is being modeled in HydroCAD. b. The infiltration basins should be removed from the model (except for Device 600i). c. Applicant should confirm total phosphorus and total suspended solids removal requirements are still being met after the model has been updated. 24. Watersheds 201 and 600 are only modeling the impervious area. The pervious area in these watersheds should be added to the model. 25. Watershed 300 in the P8 model has 25% impervious while the corresponding HydroCAD subwatershed has 45% impervious modeled. Applicant should update the models to be consistent with one another and representative of the plans. 26. The total areas listed in the table in Section III.A of the Stormwater Management Plan are inconsistent with the total area called out in the plans and the total area being modeled. Applicant should include the entire site in the areas shown in the table. 27. Any projects seeking a wetland alteration permit subject to this article will also be required to submit the following: Existing and proposed drainage areas to wetlands; Buffer strip plan meeting the criteria of subsections 20-411(c) and (d). 28. Sec. 20-416. Mitigation. Wetland mitigation shall be undertaken on site. If this is not feasible, then mitigation may occur locally within the subwatershed. If this is not possible, then mitigation may occur outside the subwatershed, elsewhere in the city. If mitigation cannot be accomplished on site, or if the city deems it necessary to perform mitigation off site, then the applicant shall be responsible for providing off-site mitigation within the major subwatershed, as designated by the Minnesota Wetland Conservation Act, or purchasing wetland credits from the state wetland bank. 29. Stormwater runoff shall not be discharged into wetlands without water quality pretreatment as prescribed by City Code. 30. If a Wetland Alteration Permit is issued allowing wetland alteration, the following standards shall be followed: (1) The alteration will not have a net adverse effect on the ecological and hydrological characteristics of remaining wetland, (2) It shall be located as to minimize the impact on vegetation, (3) It shall not adversely change water flow, (4) The size of the altered area shall be limited to the minimum required for the proposed action, (5) The disposal of any excess material is prohibited within remaining wetland areas, (6) The disposal of any excess material shall include proper erosion control and nutrient retention measures, (7) Alterations to any wetland area are prohibited during waterfowl breeding season or fish spawning season, unless it is determined by the city that the wetland is not used for waterfowl breeding or fish spawning, and (8) Alterations to wetland areas shall be mitigated in accordance with the requirements of this article if the activity results in a loss of wetland area and/or function and value of the wetland. 31. The alteration shall not alter the hydrological patterns in the remainder of the wetland, if a portion of the wetland remains, unless exempted under Sec. 20-417. Show how hydrologic patterns will not be altered for the remaining wetlands. 32. Sec. 20-405. Wetland delineation. An electronic copy of the delineated wetland boundaries must be submitted in a format compatible with the city's GIS database. 33. Sec. 20-406. Wetland classification. All wetlands delineated under Sec. 20-405 of this article that have not been previously classified shall be classified using the results from the Minnesota Routine Assessment Method for Evaluating Wetland Functions (MnRAM Version 3.0), or future versions. A MnRAM shall be completed by the property owner or applicant for each previously unclassified wetland. An electronic version of the MnRAM evaluation must be submitted to and approved by the city to establish the classification of each wetland prior to any alteration or impact to the wetland. 34. Staff review will be conditional upon the approved Wetland Replacement Plan. 35. A grading permit cannot be issued until the applicant has completed the WCA process. 36. Wetland Buffers. Wetland buffers and buffer monumentation will be required adjacent to the wetlands on site. Please indicate wetland buffer widths and locations where signage will be placed on a plan sheet. Please find additional information on signage placement in the city’s guidance document. The WMO provides signs and sign posts for the cost of materials. Alternative signs (by the city or applicant) are also acceptable provided they contain similar information. 37. Sec. 19-146. Wetland elements. a. Water level fluctuations (peak elevation and duration) for wetlands shall be limited to two feet and duration not to exceed 48 hours so as to prevent the destruction of wildlife habitat and wetland vegetation. b. Sedimentation basins or sediment removal devices shall be provided prior to discharge into wetlands. c. Variable bottom contours should be considered to provide deeper holes and flat shallow benches. This feature will provide habitat for diversity of plants and wetland inhabitants for wetland mitigation sites and stormwater basins. See revised plans and revised stormwater management plan for comments 1-37. Landscaping and Tree Preservation 1. The developer shall conduct a walk-through of the grading limits on site prior to removals with city staff to inspect for opportunities for additional tree preservation. OK 2. Tree preservation fencing shall be installed around existing trees to be saved prior to any construction activities and remain installed until completion. OK 3. All trees shall be planted outside of the street right-of-way. All trees shown on landscape plan are outside of right-of-way 4. The applicant shall increase tree planting in the development to meet minimum requirements of 590 trees. All previous city comments have been addressed and all requirements have been met with the proposed number of trees currently on the plan. 5. Buffer plantings shall be added to the east of the city well building. OK 6. The three oaks on city property (not inventoried) to the south of the city well building shall remain and the grading limits be adjusted to provide for preservation by avoiding any grading within the critical root zone areas of the trees. No grading will occur on City property 7. Autumn Blaze maples shall be eliminated from the plant schedule. Other species have replaced the Autumn Blaze 8. Northern Pin Oak shall be replaced with white, bur, red or bicolor oak species in the plant schedule. As per a conversation with the City Natural Resources person, Northern Pin Oak quantities are being significantly reduced and other species have been added. 9. Additional selections of tree species shall expand the breadth of tree types and take into consideration soil conditions and future hardiness zone changes. Additional species of trees were added to the plan 10. No tree Genus shall comprise of more than 20% of the total number of trees and no tree species shall comprise of more than 10% of the total number of trees. The tree schedule has been amended 11. The applicant shall revise the plans to show the bluff impact zone on both bluffs and eliminate grading within these areas. The plans have been revised 12. Private lot boundaries shall not encroach into bluff areas. The plans have been revised 13. Lots with significant tree cover contain conservation easements to protect the wooded areas. Lots 501, 504, 505, 530 and 531 should have protective easements over parts of the lot containing existing forest. Specifically, the rear 40 feet of Lot 501, the rear 100 feet of Lots 504 and 505, the westerly 200 feet of Lot 530, and the easterly 250-300 feet of Lot 531. Conservation easements at appropriate locations will be provided at the time of final plat for these areas. As soon as possible, provide a revised preliminary plat showing 169 lots with the engineering plans in conformance with the lot configuration. In addition, provide a revised landscaping plan, tree preservation, and lot compliance table as represented in your March 11, 2019 City Council presentation. Final plat documents and application must be submitted to the city 35 days prior to the City Council meeting in which you wish to have your final plat approved. Conditions of the preliminary plat approval must be addressed for final plat approval. Enclosed is the list of items required for submittal for final plat approval. A unique plat name must be included with the final plat submittal. The rezoning of the residential lots shall not be official until approval of the final plat and execution of the project development contract. Should you have any questions, please contact me at (952) 227-1139 or by email at kaanenson@ci.chanhassen.mn.us.